U.S. patent application number 11/400485 was filed with the patent office on 2006-11-16 for process and apparatus for manufacture of fertilizer products from manure and sewage.
This patent application is currently assigned to EarthRenew, Inc.. Invention is credited to Christianne Carin, Alvin W. Fedkenheuer, Brian N. Gorbell, John S. Jonasson, Alexander Starosud.
Application Number | 20060254080 11/400485 |
Document ID | / |
Family ID | 35597895 |
Filed Date | 2006-11-16 |
United States Patent
Application |
20060254080 |
Kind Code |
A1 |
Carin; Christianne ; et
al. |
November 16, 2006 |
Process and apparatus for manufacture of fertilizer products from
manure and sewage
Abstract
This invention discloses systems and methods for conversion of
manure to novel fertilizer and/or soil builder products useful as
input for organic farming operations. The equipment systems
comprise a gas turbine generator unit (preferred heat source), a
dryer vessel and a processing unit, wherein the connection between
the gas turbine and the dryer vessel directs substantially all the
gas turbine exhaust into the dryer vessel and substantially
precludes the introduction of air into the dryer vessel. The dryer
vessel receives the manure for contact with the turbine exhaust
gases to convert the manure to a dry material, which is passed to
the processing unit where it is formed into granules, pellets or
other desired form for the final dry fertilizer product. The method
comprises drying, heating and converting the manure to form novel
self binding fertilizer and soil builder type products for organic
farming and other uses.
Inventors: |
Carin; Christianne;
(Priddis, CA) ; Gorbell; Brian N.; (Priddis,
CA) ; Fedkenheuer; Alvin W.; (Calgary, CA) ;
Jonasson; John S.; (Tisdale, CA) ; Starosud;
Alexander; (Calgary, CA) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
EarthRenew, Inc.
Half Moon Bay
CA
|
Family ID: |
35597895 |
Appl. No.: |
11/400485 |
Filed: |
April 7, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10894645 |
Jul 19, 2004 |
7024796 |
|
|
11400485 |
Apr 7, 2006 |
|
|
|
Current U.S.
Class: |
34/363 |
Current CPC
Class: |
Y02W 30/43 20150501;
Y02W 30/40 20150501; Y02W 10/37 20150501; F26B 2200/18 20130101;
F26B 19/005 20130101; F26B 23/001 20130101; Y02E 50/12 20130101;
Y02P 20/145 20151101; F26B 23/02 20130101; Y02A 40/205 20180101;
C05F 7/00 20130101; Y02A 40/20 20180101; C05F 3/00 20130101; Y02E
50/10 20130101; Y02P 70/10 20151101; Y02P 70/405 20151101; Y02A
40/213 20180101 |
Class at
Publication: |
034/363 |
International
Class: |
F26B 3/08 20060101
F26B003/08 |
Claims
1-23. (canceled)
24. A fertilizer material or soil builder material comprising a
manure feedstock thermally treated at sufficient temperatures,
without significant oxidation and for a sufficient period of time
to provide a self-binding manure material suitable for forming into
granules, pellets or prills suitable for conventional dry
application in a crop growing operation.
25. A fertilizer material or soil builder material according to
claim 24 comprising less than about 15% by weight moisture.
26. A fertilizer product or soil builder product comprising a
manure feedstock thermally treated at sufficient temperatures,
without significant oxidation and for a sufficient period of time
to render the manure self-binding and formed into granules, pellets
or prills suitable for conventional dry application in a crop
growing operation.
27. An organic fertilizer material or soil builder material
according to claim 26 comprising less than about 15% by weight
moisture.
28-61. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 10/894,645, filed Jul. 19, 2004, entitled "Process and
Apparatus for Manufacture of Fertilizer Products from Manure and
Sewage", which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] This invention relates to processes and equipment for
economically converting manure and sewage into fertilizer
(particularly certified organic fertilizer) and soil builder
products with high organic matter content (also certified organic)
for agronomic uses.
BACKGROUND OF THE INVENTION
[0003] The number and size of concentrated animal feeding and other
agricultural operations, which produce beef, pork, poultry, elk and
other game animals, goat, lamb, fish, milk, cheese, eggs and other
foodstuffs produced from animals, have been steadily increasing for
the past 50 years. The same is true for other animal feeding
operations for sheep, mink, alpaca and other animals for production
of wool, furs and other fiber products. The primary benefit of
housing and feeding larger numbers of agricultural animals at a
single site is that the consolidated operations give an economy of
scale that lowers per unit product operating costs and improves
profitability. However, as the number and size of concentrated,
confined animal feeding operations has grown over the years, the
development of technology to treat the waste material from these
facilities has seriously lagged. The majority of the waste material
is transported to sites distant from these facilities and is
applied with little or no treatment to land where food crops are
grown. Consequently, there are environmental and health concerns
about direct application of raw or minimally treated manure to the
ground, including rainwater runoff of pollutants into surface and
ground waters and emissions of greenhouse gases to the atmosphere
due to bioconversion or decomposition. Disposal of manure is a
significant cost to the animal feeding operation, because manure is
produced in high volumes with high moisture content.
[0004] Chicken egg production in the United States has undergone
significant change in recent years. Such change is characterized by
growth of the producing flock, and individual producing sites have
become larger. For example, it is estimated that there are
currently more than 50 egg production facilities in the United
States which contain a minimum of one million laying hens.
Producers have been faced with the fact that egg production and
processing operations must become large and more concentrated to
improve economic performance in a competitive business environment.
However, these major producing facilities with more than one
million layers, typically do not use any type of manure processing
technology, but simply apply the manure to farm ground as a method
of disposal. As mentioned above, there are significant
environmental concerns with this method of disposing of manure
generated by the egg producing operation.
[0005] Animal manures from dairy, feed lot and hog facilities
typically have a moisture content in excess of 70% by weight, which
makes it difficult to handle and dispose of such manures
economically. Removing moisture for volume reduction to enable
landfill disposal is too costly and is environmentally undesirable.
Transport to farm sites for direct disposal and use on crop land is
also costly and is environmentally undesirable due to noxious odors
released on application and due to the presence of contaminants,
such as antibiotics, hormones, pesticides, etc., in the manure. In
some cases, the application of raw or concentrated raw manure could
cause plant kill in some applications due to such contaminants.
[0006] Bioconversion, commonly used for treatment of municipal
sewage and livestock waste, refers to the conversion or
decomposition of organic materials (such as organic waste) into
useful products (such as usable feed or fuel) by bacterial
decomposition of such organic matter. Bioconversion includes
anaerobic and aerobic digestion. In some cases, operators of animal
feeding operations have constructed lagoons and holding ponds to
hold manure and to allow bioconversion digestion of the waste
material before it is applied to the land. However, the condition
and operation of some of these lagoons has been the subject of
national news headlines, such as the breach of lagoon dikes in
North Carolina, Iowa and elsewhere when flooding occurs. They also
have the problems of requiring large land areas, and they have no
control of emissions of noxious odors and greenhouse or polluting
gases into the atmosphere.
[0007] While research by universities and government laboratories
has shown that animal manure may, under certain controlled
conditions, be effectively treated by anaerobic digestion, poultry
and swine manure have been shown to be among the most difficult to
treat. Conventional anaerobic digestion technology has certain
limitations in terms of slow reaction rates (low throughput),
particularly in cold climates, and the ability of the bacteria to
be productive when conditions (such as pH, temperature and
concentration of certain chemical constituents) in the digester are
not optimum. Current literature teaches that anaerobic treatment of
poultry manure can only be accomplished if the manure is diluted
with water at a weight ratio of between about 4 to 1 and about 10
to 1 water to solids. While such dilution allows for better
bioconversion and digestion of the manure, it also increases the
volume of waste that must be handled and ultimately processed for
disposal. As a result, this approach increases processing costs and
is not economically desirable.
[0008] In spite of the efforts of governments and the animal
feeding industry, there are no cost effective manure treatment
facilities in operation that are not a significant and direct
financial burden to the agricultural producer. In addition, the
processes in use, such as biogas production from manure, themselves
have environmental problems, such as producing a biodigested toxic
sludge that must be disposed of in an acceptable manner. Therefore,
new and improved methods of treating agricultural manure that
overcome the technical defects and economic disadvantages of the
prior art are highly desired.
[0009] A similar situation exists for municipal sewage due to rapid
growth of cities and inadequate building or upgrading of sewage
treatment facilities to keep up with the population growth. Aerobic
digestion is commonly used for bioconversion of municipal waste,
which also produces large volumes of dilute, high water, low
solids, content mixtures that are costly to dispose of. In many
countries a municipal sludge is produced by raising the solids
content, and the resulting municipal sludge is disposed of by
application to cropland. This is less common in the U.S. and
Canada, and in some cases, is prohibited, so the sludge has been
disposed of in landfill locations. However, due to federal, state
and local government restrictions on the volume of waste permitted
in landfill operations and the increasing fees for landfill
disposal, the emphasis of technology in recent years has been on
volume reduction of municipal waste by drying, incineration, etc.,
to reduce the cost of disposal of remaining solids in landfills.
Incineration and pyrolysis are increasingly disfavored due to air
pollution and solids disposal problems. Again, new and improved
methods of treating municipal waste and sludge to overcome the
technical and economic disadvantages of the prior art are highly
desired.
[0010] Various rules and regulations have been developed for the
purpose of sterilizing or decontaminating biological sludges,
manures and wastes. In 1993 the U.S. Environmental Protection
Agency promulgated rules for the treatment and management of
municipal sewage sludge (EPA, 1993). These rules set standards for
pathogen destruction (disinfection), vector attraction reduction
(VAR), and metal contaminant reduction in sewage sludge. The
disinfection standards are separated into two categories: Class B
in which sludges are treated to partially destroy pathogens; and
Class A where pathogenic bacteria, enteric viruses and helminth
parasites are reduced to near detection limits.
[0011] Processes previously approved by EPA as Class A disinfection
processes include: thermal treatment, based on a prescribed
time-temperature relationship; advanced alkaline stabilization with
accelerated drying, combining raising a pH above 12 for 72 hours,
heating to greater than 125.degree. F. for 12 hours, and producing
solids greater than 50%; composting; heat drying; heat treatment of
liquid sludge; thermophilic aerobic digestion; beta ray
irradiation; gamma ray irradiation; pasteurization (temperature
greater than 158.degree. F. for at least 30 minutes); a combination
of a pH reaching at least 12 and pasteurization; and several
advanced digestion processes (EPA, 1999). Processes that purport to
meet these EPA standards are costly in operation and typically do
not provide satisfactory results.
[0012] Examples of the prior art and publications that have
addressed the above problems by digestion, incineration, volume
reduction and/or decomposition are U.S. Pat. No. 5,535,528 to
Finham, U.S. Pat. No. 5,685,153 to Dickenson et al.; U.S. Pat. No.
6,039,774 to McMullen et al.; U.S. Pat. No. 6,125,633 and U.S. Pat.
No. 6,173,508 to Strohmeyer; U.S. Pat. No. 6,171,499 to Bouchalat;
U.S. Pat. No. 6,524,632 to Kartchner; U.S. Pat. No. 6,613,562 to
Dvork; U.S. Pat. No. 6,682,578 to Sower; and U.S. Patent
Application 2004/0025715 by Bonde et al., the disclosures of which
are incorporated herein by reference in their entirety.
[0013] Another problem existing in animal feeding operations and
sewage treatment is air pollution, including greenhouse gas
emissions, including methane and CO.sub.2, and gases having noxious
odors. As residential housing areas have expanded, many have
encroached on land adjacent to animal feeding operations, then
complaints from residents regarding the noxious odors escalate. In
addition to the odors and air polluting greenhouse gases produced
from the manure and bioconversion of manure, significant quantities
of the noxious and greenhouse gases are produced directly from the
animals in their flatulence, burps and regurgitation. In addition
to the need to control noxious and greenhouse gases emitted
directly from the manure (urine and feces) or from decomposition of
the manure, there is a recognized need to control the noxious and
greenhouse gas emissions from the animals themselves and prevent
same from being released into the atmosphere.
[0014] There is also increasing emphasis in developed countries on
the production of food crops by use of certified organic crop
production processes and materials. The governments of Canada,
Australia, the United States, the European Union and other
countries have developed standards for qualifying food products as
"organic" or "organically produced," and several certifying
organizations and government agencies exist to certify farms and
market produce as "organic" under the appropriate standards. The
concept underpinning "organic" food and crop production is that the
inputs used in crop or animal production (fertilizer, seeds, feeds,
sprays, etc.) are allowed to contain only minimal levels of certain
approved non-natural materials, such as synthetic chemical
fertilizers, genetically modified organisms, etc., and are allowed
to contain essentially no amounts of designated undesirable
materials, such as pesticides, drugs, growth hormones, pathogens,
etc. The following are examples of the standards setting
agencies:
CGSB--Canadian General Standards Board
Standards Council of Canada
270 Albert Street, Suite 200
Ottawa, Ontario K1P 6N7, Canada
NOSB/NOP--National Organic Standards Board/National Organics
Program
U.S. Department of Agriculture
1400 Independence Avenue, SW
Washington, D.C. 20250 USA
CAAQ--Conseil des appellations agroalimentaires du Quebec
35, rue de Port-Royal Est, 2eme etage
Montreal, QC, H3L 3T1 Canada
The Council of European Communities
Rue de la Loi/Wetstraat, 175
B-1048 Brussels, Belgium
IFOAM
Charles-de-Gaulle-Str. 5
53113 Bonn--Germany
CODEX Alimentarius Commission
FAO--Food and Agriculture Organization of the United Nations
Viale delle Terme di Caracalla
0100 Rome, Italy
FSANZ--Food Standards Australia New Zealand
Boeing House
55 Blackall Street
BARON ACT 2600
PO Box 7186
Canberra BC ACT 2610 Australia
JAS--Japan Agricultural Standards
Japanese Ministry of Agriculture, Forestry and Fisheries
Tokyo Center for Quality Control and Consumers Servic
Omiya City, Japan
COABC--The Certified Organic Association of British Columbia
#8-A 100 Kalamalka Lake Road
Vernon BC, V1T 9G1 Canada
OMRI--The Organic Materials Review Institute
PO box 11558
Eugene, Oreg. 97440-3758, USA
[0015] The following are examples of the organizations that have
been qualified and accepted by at least one standards setting
agency for certifying that specific producers/produce are in
compliance with the applicable organic standards:
FVOPA--Fraser Valley Organic Producers Association
Surrey (CB), Canada
GBE--Garantie Bio--Ecocert
Levis (Quebec), Canada
FOG--Florida Certified Organic Growers & Consumers, Inc.
Gainesville, Fla. USA
[0016] ACO--Australian Certified Organic P/L
Toowoomba, Australia
QAI--Quality Assurance International
12526 High Bluff Dr., Suite 300, San Diego, Calif. 92130 USA
OCIA International--Organic Crop Improvement Association
International
6400 Cornhusker Hwy, Suite 125, Lincoln, Nebr. 68507 USA
IOAS--The International Organic Accreditation Service
1181/2-1.sup.st Ave., South, Suite 15, Jamestown, N. Dak. 58401
USA
ICS--International Certification Services, Inc.
301 5.sup.th Ave. SE
Medina, N. Dak. USA
ICS/FVO--International Certification Services, Inc.
Farm Verified Organic
301 5.sup.th Ave. SE
Medina, N. Dak. USA
CCOF--California Certified Organic Farmers Inc.
Santa Cruz, Calif. USA
CERTIMEX--Certificadora Mexicana de Productos y Proceso Ecologicos
S.C.
Oaxaca, Mexico
IMO--Institut fur Marktokologie
Weinfelden, Switzerland
SACL--Soil Association Certification Ltd.
Bristol, United Kingdom
[0017] These standard setting organizations and agencies have been
developed due to the rapidly increasing consumer demand, not only
for organic products, but for some reliable standards so consumers
can have confidence in the organic product labeling. Thus, the
"certified organic" labeling and terminology have been developed to
mean products or produce certified by recognized organizations as
meeting the applicable agency standards and product or produce made
by methods that meet the agency standards for organic production
methods.
[0018] One essential aspect of certified organic food production is
the necessity of using inputs that are certified organic, such as
fertilizers, which are either approved, such as materials
containing no pathogens or other disqualifying components, or
regulated and accepted, such as manures, composts and the like that
meet the applicable standards. Technology developed to date for
producing certified organic fertilizer products has not been
satisfactory due to one or more problems in product quality,
environmental acceptability or economic feasibility for providing a
reasonably priced commercial product. Examples of the prior art and
publications that have addressed the production of organic or
certified organic fertilizer products are U.S. Pat. No. 5,354,349
to Inoue; U.S. Pat. No. 6,461,399 to Connell; U.S. Pat. Nos.
6,517,600 and 6,645,267 to Dinel; U.S. Patent Applications
2003/0038078 by Stamper et al., 2003/0089151 and 2003/0136165 by
Logan et al., and 2003/0111410 by Branson, the disclosures of which
are incorporated herein by reference in their entirety.
[0019] It is apparent from the above that there is a substantial
unmet need for environmentally and economically acceptable
technologies for disposal of manure and sewage, for control of
noxious and greenhouse gases from animal feeding operations, and
for production of organic fertilizer and soil builder products that
can be certified for food production inputs under established
standards for certified organic food production. The present
invention is directed to methods, apparatus, systems and products
for meeting one or all of these needs.
SUMMARY OF THE INVENTION
[0020] The present invention provides economical and simplified
methods, systems and apparatus for converting manure feedstocks to
fertilizer and soil builder products, preferably conversion to
certified organic fertilizer and soil builder products. The present
invention further provides economical and simplified methods,
systems and apparatus for controlling and containing noxious,
odoriferous and greenhouse gases from animal feeding
operations.
[0021] In one aspect, this invention provides a method for
producing an organic fertilizer product from manure feedstock
comprising operating a gas turbine generator to produce electricity
and exhaust gases; contacting the exhaust gases with the manure
feedstock having a moisture content of at least about 30% by weight
in a dryer vessel for a contact time sufficient to produce, without
significant oxidation of the manure feedstock, a dried fertilizer
material having a moisture content less than about 20% by weight;
and processing and forming the fertilizer material into a granular,
pellet or prill form of fertilizer product suitable for
conventional dry fertilizer application in a crop growing
operation.
[0022] In another aspect, this invention provides a method for
producing a fertilizer material from manure feedstock comprising
operating a gas turbine generator to produce electricity and
exhaust gases having a temperature greater than 1,000.degree. F.;
contacting the exhaust gases having a temperature greater than
1,000.degree. F. with manure feedstock having a moisture content of
at least about 30% by weight in a dryer vessel for a contact time
sufficient to produce, without significant oxidation of the manure
feedstock, a dried fertilizer material having a moisture content of
less than about 20% by weight, and optionally provides a method
further comprising the steps of granulating, pelletizing or
prilling the fertilizer material to produce a fertilizer product
suitable for conventional dry fertilizer application in a crop
growing operation.
[0023] In another aspect, this invention provides apparatus for
drying and/or converting manure feedstock to produce a fertilizer
and/or soil builder material comprising a gas turbine in
combination with a dryer vessel adapted for receiving manure
feedstock and for receiving the exhaust gases from the gas turbine
through a connection; wherein the connection between the gas
turbine and the dryer vessel is adapted to substantially preclude
the introduction of air into the dryer vessel and optionally
provides the dryer vessel adapted for such drying and/or converting
the manure feedstock by direct contact of the exhaust gases and the
manure feedstock.
[0024] In another aspect, this invention provides a portable system
for processing manure feedstock to produce a fertilizer product
comprising at least one portable dryer unit adapted for drying a
manure feedstock to produce a fertilizer material and at least one
portable processing unit adapted for converting the fertilizer
material from the dryer unit into a fertilizer product having a
form suitable for conventional fertilizer application in a crop
growing operation, and optionally further provides such a portable
system wherein the dryer unit comprises a gas turbine and a dryer
vessel. Further, the invention optionally provides such a portable
system wherein the gas turbine and dryer vessel are connected by an
arrangement adapted to pass the gas turbine exhaust gases into the
dryer vessel and to preclude the introduction of air into the dryer
vessel.
[0025] In another aspect, this invention provides the above
portable system comprising a first skid-mounted unit comprising the
gas turbine generator adapted for producing electricity; and a
second skid-mounted unit comprising the dryer vessel adapted for
connection to the gas turbine to receive the gas turbine exhaust
gases and to preclude the introduction of air into the dryer
vessel. Optionally a third skid-mounted unit is provided comprising
the processing unit. Preferably the portable systems of this
invention comprise rail-mounted, truck-mounted or
semitrailer-mounted units. In another aspect, this invention
provides the portable system, comprising the gas turbine and dryer
vessel, plus an optional processing unit, configured and sized for
a single skid-mount or truck-mount installation. Another optional
aspect comprises an enclosure or enclosures for the portable units,
primarily for operating noise attenuation.
[0026] In another aspect, this invention provides an organic
fertilizer material comprising a manure feedstock thermally treated
at sufficient temperatures and without significant oxidation for a
sufficient period of time to destroy or convert to harmless forms
substantially all undesired components present in the manure
feedstock which comprise undesired organisms, microorganisms,
pesticides, antibiotics, hormones, prions or viruses. Preferably
the organic fertilizer material contains less than detectable
levels of each such undesired component not so destroyed or
converted, and optionally further provides such fertilizer material
in the form of a fertilizer product suitable for conventional dry
fertilizer application in a crop growing operation. This invention
further provides a fertilizer material or product comprising
thermally treated manure feedstock which contains NO.sub.x,
SO.sub.x or CO.sub.x components absorbed or complexed therein as a
result of contact of the manure feedstock with gas turbine exhaust
gases in a confined space in the absence of significant oxidation
of the manure feedstock. Depending on the relative nutrient content
and organic matter content of the manure feedstock, this aspect of
the invention is equally useful for providing a high organic matter
content soil builder product having similar characteristics.
[0027] In another aspect, this invention provides a fertilizer
material or product comprising a manure feedstock thermally treated
at sufficient temperatures without significant oxidation and for
sufficient period of time to provide a self-binding fertilizer
material or product suitable for conventional dry fertilizer
application in a crop growing operation.
[0028] In another aspect, this invention provides a method for
producing a soil builder product from a bioconverted manure
feedstock comprising operating a gas turbine generator to produce
electricity and exhaust gases, contacting the exhaust gases with
the manure feedstock having a moisture content of at least about
30% by weight in a dryer vessel for a contact time sufficient to
produce, without significant oxidation of the manure feedstock, a
dried soil conditioner material having a moisture content less than
about 20% by weight and optionally processing and forming the soil
conditioner material into a granular, pellet or prill form of soil
conditioner product suitable for conventional dry application to
the soil.
[0029] In another aspect, this invention provides a system for
processing animal gases and noxious or odoriferous odors or gases
from manure feedstock comprising a gas turbine having a combustion
air intake and an animal shelter having ventilation air exhausted
from the shelter, wherein the combustion air intake is adapted to
receive at least a portion of, and preferably substantially all of
the ventilation air exhausted from the animal shelter. The gas
turbine can optionally comprise a gas turbine generator and can
optionally include a dryer vessel adapted for receiving the gas
turbine exhaust and for receiving and treating manure feedstock. In
an alternative aspect, this invention provides said systems for
processing animal gases and noxious or odoriferous odors or gases
through the combustion air intake of a reciprocating engine, which
can optionally include an electric generator and can optionally
include a dryer vessel adapted for receiving the engine
exhaust.
[0030] In another aspect, this invention provides apparatus for
treating manure feedstock comprising a gas turbine having a
combustion air intake adapted to receive ventilation air from an
animal shelter, a dryer vessel having a connection adapted for
receiving exhaust gases from the gas turbine and having an inlet
for receiving manure feedstock. Optionally the combustion air
intake can be adapted for connection to the animal shelter
ventilation system whereby the combustion air intake receives
substantially all the ventilation air exhausted from the animal
shelter. Additionally in this aspect, the connection between the
dryer vessel and the gas turbine exhaust can be adapted to
substantially preclude the introduction of air into the dryer
vessel.
[0031] The above aspects and other aspects will be apparent to one
skilled in the art from the disclosure herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a schematic diagram of a process for treating
manure feedstock using the process and equipment in accordance with
the present invention.
[0033] FIG. 2 is a plan view of the process units according to this
invention in the form of portable skid-mounted, truckable
units.
[0034] FIG. 3 is a plan view of the process units according to this
invention in the form of portable skid-mounted, truckable units in
another configuration.
[0035] FIG. 4A is a plan view and FIG. 4B is an elevation view of
an illustration of a configuration of the system of this invention
mounted on a semitrailer truck.
[0036] FIG. 5 is a schematic of processes for preventing emission
of animal gases and greenhouse gases to the atmosphere using the
systems of the present invention.
DESCRIPTION OF THE INVENTION
[0037] This invention provides an economical, efficient and
simplified solution to the increasingly severe problem of
environmental pollution caused by manure and gases from livestock
operations and by sewage from municipalities. Prior art methods and
systems provided to date either are not sufficiently effective in
conversion of such manure and gases to a safe, environmentally
acceptable form or are not adaptable to be economically feasible
for small as well as large commercial operations. Other problems
exist with many of the prior art systems, such as uneconomical to
operate, failure to decontaminate and failure to prevent air
pollution (or in fact causing additional environmental problems in
the operation of the process).
[0038] Examples of the prior systems and their deficiencies include
the following. Digestion processes, whether aerobic or anaerobic,
are slow, inefficient and produce a sludge that must be disposed
of, typically in a landfill or land spreading. Digestion or
composting systems designed to produce biogas, typically methane,
for fuel do not provide economically beneficial fuel production and
are costly to operate, because the fuel produced is not produced at
a sufficient rate, is not of sufficient thermal value for economic
operation. It is a "dirty" fuel in that it produces environmentally
unacceptable emissions when burned and is difficult to burn
efficiently due to its variable content. This variable and
inconsistent content of contaminants and fuel value can actually
damage some systems, such as gas turbines and reciprocating
engines, due to corrosion or uncontrollable burning conditions.
Digestion and composting systems designed to produce fertilizer or
soil conditioner products have the drawback that such products
produced are not free of biologic or chemical contaminants that are
undesirable or prohibited for use on crop land, particularly for
certified organic uses, and such products are too low in nutrient
value to serve as an effective fertilizer. Biogas production
operations produce a depleted sludge that is costly to dispose of
in an environmentally acceptable way.
[0039] Treatment systems that employ heat and chemical treatment
are inefficient and frequently ineffective in producing a safe
final product. These include pH adjustment and chemical additives,
usually with heating to help kill organisms present. Some heat
treatment systems employ pressure (for higher temperature cooking),
microwave heating, radiation and other supplemental treatments,
which only serve to add to the cost of operation with diminishing
benefit in product quality or environmental cleanup. In many cases
the additional complexity of treatments and combinations of process
steps results in more negative environmental impact from the
resources employed and byproducts produced than is achieved in
beneficial environmental impact from the total treatment. Many
systems produce alternative or additional byproducts that are
contaminated or cause collateral environmental pollution in their
operation. Systems that involve incineration, partial incineration,
gasification or pyrolysis are similarly inefficient and not
sufficiently effective, because incineration produces additional
effluents that must be contained to prevent alternate or additional
air pollution. Also, while incineration systems produce a product
that may be sufficiently sterilized, the product may contain other
undesirable byproducts of the incineration making it unsuitable for
some fertilizer uses, thus requiring undesirable disposal in
landfill. And, incineration systems carry the additional risk of
potentially uncontrollable or flash fires, which at a minimum
damages the processing equipment and at worst poses safety
issues.
[0040] Prior art systems have not satisfactorily addressed the
problem of noxious gases and greenhouse gases that are produced in
animal feeding operations and municipal sewage treatment
operations. Sources of such gases are the animals themselves, the
manure and waste from the animals and the bioconversion or
decomposition of the manure, sewage and waste. These gases are
typically vented or released to the atmosphere, but are
objectionable to nearby residents due to the noxious odors and are
environmentally objectionable due to the atmospheric pollution
caused by the greenhouse gases contained therein, particularly
methane.
[0041] The present invention provides new technology in the form of
processes, apparatus and systems for conversion of manure feedstock
to useful, environmentally acceptable materials and products, which
in one preferred aspect can be produced in a form suitable for use
in certified organic agricultural operations. As disclosed herein,
the present invention provides technology which reduces or
eliminates the undesirable environmental impacts of greenhouse
gases produced in animal feeding operations, and the technology of
this invention also reduces or eliminates the undesirable
environmental impacts of manure feedstock treatment compared to the
prior art processes and systems. One of the major advantages of the
present invention resides in the aspect that in most manure
feedstock processing all waste solids are contained and become part
of the final product useful as a fertilizer or soil builder
material. Thus, the present invention can completely eliminate the
necessity of disposing of any remaining sludge or other solids in a
landfill or by land spreading.
[0042] The term "manure feedstock" is used herein to mean and
include waste matter excreted from animals as feces and/or urine,
such as but not limited to human (municipal sewage or sludge),
cattle (beef, dairy, buffalo, veal, etc.), horses, sheep, swine,
poultry (chicken, turkey, ostrich, pigeon, etc.), goat, mink,
veterinarian, stockyard, stable, race track, rodeo grounds,
fairgrounds, feedlot, sale barn, zoo, aquatic (fish, shrimp, etc.),
elk (and other game), llama, alpaca, as well as other operations
and sources of sewage or manure, and any mixtures thereof. Manure
feedstock as used herein includes such matter along with other
materials normally present in agricultural operations where such
matter is produced, such as straw, bedding (which is typically
shredded paper, wood chips, etc.), hair, feathers, insects,
rodents, etc., whether the ratio of such matter to such other
materials ranges from very low to very high. Manure feedstock as
used herein includes such matter in its raw form, any prepared form
and mixtures thereof with other materials such as other bio matter
(yard waste, green waste, etc.), additives, process aids, bone
meal, fish meal and the like, including where the matter is fresh,
fully bioconverted by composting, digestion, etc., or is at any
stage in between. It will be recognized that, when other
components, such as bone meal, etc., are added to, mixed with or
included in the manure feedstock for processing according to this
invention, such additional components will also benefit from the
thermal destruction or conversion of the undesirable components
listed above, such as prions, etc., just as the manure feedstock
does. Thus, it may be desirable to mix contaminated materials, such
as straw containing pesticides, bone meal containing prions, etc.,
with the manure to be processed, so that those contaminants can be
converted or destroyed during the processing of the manure
feedstock according to this invention. This invention is useful in
processing other types of waste products and waste streams, as
disclosed in commonly assigned copending U.S. patent application
Ser. No. 10/895,030, filed on Jul. 19, 2004, the disclosure of
which is incorporated herein by reference in its entirety.
[0043] The present invention provides a simplified, economically
efficient alternative to the prior art and provides in its
preferred aspects, a product 100% usable as fertilizer and/or soil
builder products, and which provides 100% conversion of manure
feedstock solids to useful products, which eliminates the problem
unsolved by the prior art of disposal of solids left over from
various manure feedstock treatments, such as composting and biogas
production. In a preferred aspect of this invention, the fertilizer
produced is an organic fertilizer usable by certified organic food
producers without jeopardizing their certified organic product
status. According to the present invention, the nutrient value of
fertilizer produced from a manure feedstock can be maximized if
composting, digestion, incineration and oxidation of the manure
feedstock are avoided or at least minimized. In this invention, the
high temperature treatment of manure feedstock, preferably by
direct contact with hot gases, e.g., >1,000.degree. F., destroys
or converts to harmless forms substantially all undesirable
components present in the manure feedstock, including organisms,
microorganisms (including genetically modified organisms, bacteria,
pathogens and other microorganisms), seeds, pesticides,
antibiotics, hormones, prions and viruses, particularly when such
heat treatment takes place for a sufficient time and without
significant oxidation, incineration or pyrolysis of the manure
feedstock. The treatment at sufficiently high temperatures for a
sufficient amount of time in the absence of significant oxidation
and/or pyrolysis "cooks" or otherwise converts or transforms the
manure feedstock into a self-binding product, whereby it can be
formed into conventional pellets, granules, prills or other forms,
usually without the need for addition of binders or other
agglomerating additives, which have sufficient physical hardness
and strength to be formed into conventional shapes and sizes and to
be used in conventional dry fertilizer application equipment and
operations. This invention also provides for recovering and
recycling the water removed from the manure feedstock, which water
can be used for livestock water, irrigation or other industrial
uses, and for recovering and recycling all solids (fines or other)
produced in the process, so that there are no significant solid
products produced other than the desired fertilizer and/or soil
builder products suitable for commercial use.
[0044] According to this invention, a most efficient way of
providing the hot gases for contact with the manure feedstock is
the exhaust from a gas turbine, and preferably a gas turbine
electric generator. According to the system of this invention, the
gas turbine is fueled from locally available conventional fuel
sources, because in the operation of this invention no
bioconversion takes place and no biogas is generated from the
manure feedstock, and because conventional fuels provide the most
efficient, reliable and controllable operation of the gas turbine.
The electricity produced from the gas turbine generator is
preferably sold back into the local power grid as a revenue source
for the operation of this invention, but it can be used internally
in the operation of the system of this invention or in other nearby
operations as a supplemental source of power or in a combination of
uses for power and heat recovery from the processes employed in
this invention. It is preferable and more efficient in the
operation of this invention to merely sell the electric power
produced to the local power grid. This enables varying the
operation of the processes and equipment of this invention in the
most efficient and effective manner for treatment of the manure
feedstock to produce the desired quality of fertilizer or soil
builder products without concern for or being constrained by any
particular minimum or necessary level of electricity output.
[0045] One important feature of the process and apparatus of this
invention is that the gas turbine and the manure feedstock dryer
vessel receiving the exhaust gas from the gas turbine are connected
together such that induction of outside air into the dryer vessel
is precluded and the dryer vessel preferably receives the exhaust
gases directly from the gas turbine. It is preferred that 100% of
the gas turbine exhaust gases are passed into the dryer vessel and,
for most efficient operation, preferably without passing through
any intervening heat exchanger, silencer or other equipment in
order that the dryer vessel receives the maximum heating from the
gas turbine exhaust. But, it is recognized that excess exhaust
gases not needed for the dryer vessel operation can be diverted to
provide heat required in other steps in the systems of this
invention or in other nearby operations. It is also preferred that
the exhaust gases result from conventional and efficient combustion
ratios in the gas turbine so that the exhaust gases contain minimum
or limited amount of free oxygen, essentially no unburned fuel, no
exposed flame and that the optimum exhaust gas temperature (EGT) is
achieved, for maximum heat produced, per unit of fuel consumed. The
combustion can also be at stoichiometric ratio for peak EGT
operation at maximum temperature, and maximum heat input for the
process. The absence of excess oxygen in the exhaust gases,
precluding outside air induction into the dryer vessel, the absence
of exposed flame and operation at the temperature set forth herein
prevents significant oxidation of the manure feedstock in the dryer
vessel, preserves the maximum nutrient value in the manure
feedstock for containment in the end fertilizer product, prevents
the danger of fire damage to the equipment and provides an
operation safe from flash fires in the dryer vessel. The absence of
excess fuel in the exhaust gases prevents the exhaust gases from
being a source of hydrocarbons that must be scrubbed from the vapor
effluent from the operation of this invention before being released
into the atmosphere.
[0046] In the operation of the processes and apparatus of this
invention, it is preferred that the manure feedstock be as fresh as
possible with a high moisture content. In other words, the manure
feedstock should have undergone no, or as little as practical,
composting, digestion or other bioconversion prior to processing
according to this invention. This provides the highest nutrient
value and organic matter content in the produced fertilizer and
soil builder product. This preferred aspect is efficiently achieved
by a preferred design of the systems of the present invention,
which is the modularization of the process units in skid-mounted or
other form suitable for transport by truck. This enables the entire
system of this invention to be sized appropriately and placed
on-site at feedlots, chicken barns, hog farms, etc., and enables
processing of the manure feedstock from such operations immediately
after it is produced. This preferred system for such operations
provides additional economic and environmental efficiency, because
it eliminates the cost and environmental impact of transporting any
manure feedstock or depleted sludge to a distant location for
processing or disposal. Eliminating the necessity of transporting
manure feedstock from one location to another also provides the
benefit of biosecurity between facilities, i.e., it eliminates the
transport and spread of harmful or undesirable plant and animal
diseases. This design also enables custom or jobber manure
feedstock processing where the truck mounted units are easily moved
from one manure feedstock accumulation site to another, in order to
maximize the utilization of the capital investment in the equipment
employed for carrying out this invention. Such portability also
enables full utilization of the equipment of this invention, which
can be scaled to an appropriate size for efficient, economical
operation, so it can be used on a part time basis at each of
several different feed lots, hog farms, etc., in a particular area
where a permanent installation at any single location is not needed
or is not economically justifiable. The systems of this invention
can also be scaled to appropriate size for an individual animal
feeding operation to operate full time to continually process the
manure continually produced in the operation, so that manure
stockpile or excess manure at any time the feeding facility is in
operation is minimized. Similarly, the systems of this invention
can be sized for installation at office buildings, hospitals,
hotels, etc., to intercept and process raw sewage therefrom to
reduce the burden on municipal sewage treatment facilities. With
many municipal sewage treatment facilities reaching full capacity
and the cities being faced with major capital expenditures to build
new or expanded facilities, this invention provides an economically
attractive alternative by processing waste streams on site at large
manufacturing facilities to produce a useful product and relieve
the burden on the municipal sewage system. The systems of this
invention can also be adapted to sanitarily treat, on site, raw
sewage from office buildings, hospitals, hotels, etc., to produce,
on site, a fertilizer product, thus further relieving the burden on
the municipal sewage system. This aspect of the systems of this
invention can be particularly useful at remote resort locations,
where municipal sewage treatment facilities are not available, to
process the sewage therefrom to produce a fertilizer product and
eliminate the problems of sludge disposal.
[0047] For use in this invention, it is preferred that the manure
feedstock have a high moisture content, such as at least 30% by
weight water, preferably at least 50% and most preferably at least
70%. The high water content facilitates mechanized handling of the
raw material and preparing it for use by blending and mixing for
uniformity of feedstock. Typically the manure feedstock is moved by
augers, front end loaders, back hoes, conveyor belts and the like,
particularly in cattle and poultry operations. However, in some
installations the manure feedstock may be prepared in the form of a
pumpable slurry, particularly in dairy and swine operations, where
barn cleaning may be done by water flooding and the water content
of the manure feedstock may be as high as 90%, 95% or even 98%.
Prior to this invention, such manure feedstocks could not be
economically processed and were simply put in holding or settling
ponds, or lagoons which have major air pollution, odor and
environmental problems. The present invention efficiently and
economically processes such high water content manure feedstocks to
not only recover the manure content in the form of a high nutrient
fertilizer, but to also recover the process water, which is
decontaminated from pathogens, etc., and can be recycled for barn
cleaning, for livestock drinking water or for crop irrigation. This
invention can handle high water content manure feedstocks
efficiently and economically due to the fact that excess steam
produced in the dryer vessel can be used downstream, upstream or in
other nearby operations, such as barn cleaning, preheating manure
feedstock, greenhouse heating, etc. Instead of holding such high
water content manure feedstocks in open ponds, this invention
enables holding the manure in enclosures or tanks, which eliminates
the air pollution, odor and environmental problems associated with
open ponds. This invention contains and processes not only the
water and solids but also the gases produced, as disclosed herein.
As noted, it is preferred for this invention that the manure
feedstock be as fresh as practical, having undergone as little
bioconversion as possible, such as by composting or digestion. In
some cases where manure must be held or stored before processing,
it may be desirable to cool the manure feedstock at the source
installation or a storage location, such as disclosed in EP 0677237
to Claesen, in order to minimize bioconversion before the manure is
processed into fertilizer according to this invention. Minimizing
the bioconversion, particularly by immediate processing according
to this invention, with or without such cooling, has the added
environmental benefit of reducing noxious or harmful emissions into
the atmosphere and the economic benefit of eliminating or reducing
the need for odor amelioration or emission control equipment at the
agricultural operation. In some cases it may be desirable for
economic operation reasons to mechanically separate part of the
water from high-water content manures, e.g., by centrifuges, before
processing the manure in the system of this invention. Such
separated water can be recycled for use, such as in floor cleaning
or for other process water requirements.
[0048] It is recognized that raw manure feedstock will typically
contain other material such as straw, twine, wire, gravel, rocks,
jute or plastic bags, etc. Such materials are processable as part
of the manure feedstock in the present invention without
detrimental effect, provided the levels of such other materials are
not unusually high. However, it is normally preferred to separate
out such materials, particularly rocks, wire and the like, that
might damage the dryer vessel or downstream processing equipment.
Otherwise, it may be desirable to prepare the manure feedstock by
chopping, grinding or other preparation to comminute items such as
twine, bags and the like into small pieces so they can be processed
into the final fertilizer product without significant interference
with the normal operation of the processes and apparatus of this
invention or with the end use of the fertilizer product. It should
be noted that such materials that are either inert or are
biodegradable can be contained in the fertilizer product without
detrimental effect, which may be particularly desired where it is
not economically efficient to remove such materials from the manure
feedstock or during processing according to this invention. The
manure feedstock preparation by grinding, chipping, chopping,
crushing, etc., not only will improve the uniformity of the
feedstock for processing, but will also facilitate addition of
other materials into the feedstock, such as straw, woodchips, yard
waste, etc., as referred to above. In addition the manure feedstock
preparation can include a washing step, which may be useful in very
dry manure, such as poultry, or to remove excess salt content that
may not be desired in a final fertilizer or soil builder
product.
[0049] While it is preferred that the manure feedstock has
undergone no or little bioconversion by composting, digestion,
etc., it is recognized that this invention is equally useful in
drying and processing fully bioconverted (composted or digested to
exhaustion) manure feedstock to produce a useful material or
product. The fertilizer nutrient value of such a material or
product may be minimal but the material or product may be useful as
a soil conditioner. The term "bioconverted manure feedstock" as
used herein is intended to mean a feedstock in which a sufficient
portion of the nutrients therein have been converted by composting,
digestion, etc., to render the feedstock more suitable for
production of a soil conditioner or soil builder product than for
production of a fertilizer product. It will also be recognized that
the manure feedstock useful in this invention include those where
the actual animal waste (feces and/or urine) is a small percentage
of the manure feedstock with the remainder being other materials,
such as straw, bedding, etc. For example, in some chicken feeding
operations, shredded paper is used for nesting/bedding material and
it is changed often enough that the manure feedstock from such
operations may be a low percentage by weight, such as about 10% to
about 30% waste, and about 50% to about 80% other material with the
remaining 10% to 20% being water. Even such manure feedstock is
advantageously processed by this invention to produce a soil
builder and/or fertilizer products.
[0050] The term "gas turbine" is used herein to mean and include
any turbine engine having a compressor turbine stage, a combustion
zone and an exhaust turbine stage that is capable of producing
exhaust gas temperatures of at least 500.degree. F., preferably at
least about 700.degree. F., more preferably at least about
900.degree. F. and most preferably greater than about 1,000.degree.
F. Gas turbines are the heat source preferred for use in this
invention because of their efficient operation and high heat
output. The gas turbine generator is further preferred for use in
this invention due to the production of energy by the generator,
which energy can be utilized or sold to improve the economics of
the operation of the system of this invention. The generator will
typically be an electric generator due to the convenience of using
and/or selling the electricity produced. However, the generator can
be any other type of energy generator desired, such as a hydraulic
pump or power pack that can drive hydraulic motors on pumps,
augers, conveyors and other types of equipment in the system of
this invention or equipment in other nearby operations. The heat
requirements and the system economics will determine whether a gas
turbine or gas turbine generator is used. If it is desired to have
higher temperature exhaust gases and higher heat output from a
given smaller size gas turbine, it may be desired to use a gas
turbine instead of a similar size gas turbine generator. Compared
to the gas turbine, the gas turbine generator further expands and
cools the exhaust gases in absorbing energy to drive the generator,
where in a gas turbine that energy is contained in higher
temperature gases available for use in the dryer vessel of this
invention. This can be an option when it is economically more
important in the practice of this invention to have small
(truckable) high temperature units than to have the revenue stream
or economic benefit of the electricity or other energy production
by the gas turbine.
[0051] The gas turbine or gas turbine generator useful in this
invention can be fueled from any available source with any suitable
fuel for the particular gas turbine and for the process equipment
designed according to this invention. The preferred and
conventional fuels are sweet natural gas, diesel, kerosene and jet
fuel because the gas turbines are designed to run most efficiently
on good quality fuels of these types and because of their common
availability, particularly at remote agricultural operations, where
the units of this invention are often most efficiently located.
However, other fuels that can be used to fuel the gas turbine
include methane, propane, butane, hydrogen and biogas and bioliquid
fuels (such as methane, oils, diesel and ethanol). Since the system
of this invention does not produce a biofuel, the fuel for the gas
turbine used in this invention must be available at the local site
where this invention is utilized. If fuel is not available locally,
a fuel such as diesel can be trucked to the site as needed.
[0052] Examples of commercially available gas turbines and gas
turbine generators useful in the present invention include the
following (rated megawatt (MW) outputs are approximate):
[0053] Rolls Royce Gas Turbine Engines Allison 501-KB5, -KB5S or
-KB7 having a standard condition rated output of 3.9 MW
[0054] European Gas Turbines Tornado having rated output of 7.0
MW
[0055] Solar Mars 90 having rated output of 9.4 MW and Solar Mars
100 having rated output of 10.7 MW
[0056] Solar Tarus 60 having rated output of 5.5 MW and Solar Tarus
70 having rated output of 7.5 MW
[0057] For a nominal product output capacity of 2.5 metric tons/hr.
(2,500 kg/hr) a gas turbine generator size of about 4 MW can be
used, depending on the heat insulation and heat recovery
efficiencies designed into the overall system. For small single
semitrailer or truck systems, the units may be scaled smaller. For
smaller product output systems, such as an 0.3 metric ton/hr
product output, small gas turbines, such as Solar Saturn 0.8 MW,
Solar Spartan 0.2 MW or Capstone 0.5 MW or 0.3 MW generators, can
be used depending on system efficiencies and required heat input
ranges. It will be recognized that systems according to this
invention can also be designed to utilize the exhaust gas heat from
reciprocating engines, such as gasoline or diesel generators. Such
small systems can be used at temporary sites, such as rodeo
grounds, to provide electricity, clean up the fresh and old manure
and produce a fertilizer product.
[0058] The dryer vessel employed in this invention can be any type
or configuration that is suitable for drying the manure feedstock
available and that can be adapted for receiving the gas turbine
exhaust gases and receiving the manure feedstock without allowing a
significant amount of outside air to enter the drying chamber in
the dryer vessel where the exhaust gases contact the manure
feedstock. The objective of the design of the gas turbine exhaust
connection to the dryer vessel for purposes of this invention is to
preclude any significant outside air from entering the dryer vessel
to help prevent significant oxidation of the manure feedstock. As
previously pointed out, this is to preserve the organic matter,
carbonaceous and/or nutrient values present in the manure
feedstock, to prevent fires and to provide a safe operation. As
used in this invention it is preferred and expected that the
turbine will be operated at a conventional ratio of fuel to
combustion air in order to produce the most efficient exhaust gas
temperature (EGT) for the dryer vessel and to produce gases
entering the dryer vessel that contain a minimum of free oxygen. It
will be recognized by those skilled in the art from the disclosure
of this invention, that alternate sources of hot gases other than a
gas turbine can be used and connected to the dryer vessel, such as
the exhaust from conventional oil or gas burners and reciprocating
engines, provided they are operated at conventional combustion
ratio conditions to minimize free oxygen, or at stoichiometric
ratio for no free oxygen, in the exhaust and are connected to the
dryer vessel in a fashion that precludes significant outside air
from entering the dryer vessel in order to preclude significant
oxidation of the feedstock. Of course, such an alternate and
additional source of hot gases can optionally be connected to the
dryer vessel according to this invention and be used to supplement
the exhaust gases output of the gas turbine in order to provide
additional heat input capacity for the dryer vessel if needed for
start up, shut down or surge load conditions or for backup in the
event the gas turbine goes off line.
[0059] It will be recognized in the operation of this invention,
that not all outside air can be excluded and oxidation of the
manure feedstock cannot be completely precluded, primarily because
of the air present in and entrained in the manure feedstock, the
air dissolved in the moisture present in the manure feedstock and
excess oxygen that may be present in the turbine exhaust gases
during periods that stoichiometric ratio of fuel and air is not
achieved. In addition, in some cases oxygen may be produced or
liberated from the organic or other materials present in the manure
feedstock when the thermal treatment and conversion takes place and
decomposes or converts such materials. Therefore, the terms as used
herein which refer to "preclude introduction of air," "without
significant oxidation," and the like, are used in the above
operational context and with the recognition and intended meaning
that the air or oxygen entering the system as part of the manure
feedstock or exhaust gases or produced in the thermal conversion
process is not intended to be precluded and that the oxidation that
may occur as a result of that air entering the system with the
manure feedstock is not intended to be prevented. However, such a
level of oxidation is not considered significant within the scope,
context and practice of this invention or the meanings of those
terms as used herein. Similarly, "without significant pyrolysis" is
used herein to mean that not more than an insignificant portion of
the manure feedstock is pyrolized, e.g., as in U.S. Pat. No.
6,039,774. Pyrolysis products are undesirable in the processes and
products of the present invention, and the processes and equipment
of this invention are operated to achieve the desired drying of the
manure feedstock and the desired conversion and destruction of
various manure feedstock components, such as pesticides, prions,
organisms, seeds, etc., but operated to avoid significant oxidation
and preferably to avoid significant pyrolysis, or at least to
minimize oxidation and minimize pyrolysis. Following the
disclosures herein, it will be apparent to one skilled in the art
to control the exhaust gas temperatures, the contact times and/or
residence times in the dryer vessel, the moisture content of the
solids and of the vapor phase in the dryer vessel and other
variables in order to process a particular manure feedstock to
achieve these desired results and to maximize the nutrient value in
the final products.
[0060] Dry or low moisture content manure feedstock is likely to
have more air entrained in the interstices among the particles than
wet or high moisture content manure feedstock, and elimination of
such entrained air from a dry manure feedstock before introduction
into the dryer vessel may not normally be economically practical.
However, consistent with other operational aspects of this
invention, it is therefore preferable to use high moisture, low air
content manure feedstock, and may be preferable to add water to a
dry manure feedstock to displace air therefrom before processing in
the systems of this invention. Minimizing introduction of air and
oxygen into the dryer vessel is preferred to prevent significant
oxidation of the nutrient components of the manure, as well as
other components of the feedstock, such as straw, dust, etc., that
might pose a fire or safety hazard if excess air or oxygen were
present in the dryer vessel.
[0061] Exclusion of outside air is also preferred for economic
efficiency as well, because heating excess or outside air along
with heating the manure feedstock reduces the efficiency of the
process. In some instances where the manure feedstock is very low
in moisture content or too dry for preferred operation of this
invention, water can be added to the feedstock, to the turbine
exhaust, to the turbine intake or to the dryer vessel to raise the
moisture level in the dryer vessel to a level for efficient
operation and to produce a solids material from the dryer vessel
with a desired moisture content and desired self-binding
properties. Addition of water to a dry manure feedstock followed by
mixing, kneading or pressing, such as in windrow mixing and
pressing with a roller, can also serve to displace air from the
feedstock before being introduced into the dryer vessel. In the
case of very dry manure feedstocks, water may be considered a
process aid added before entry into the dryer vessel.
[0062] It will be recognized that the operation of the dryer vessel
is normally to dry the manure feedstock, but it is to also achieve
the high temperature heating of the manure feedstock to convert or
destroy undesired components and to achieve a chemical or thermal
alteration in the feedstock to provide binding and particle
hardness profiles desired in the final product. As noted, an
important aspect of this invention is the thermal conversion of the
various components of the manure feedstock without significant
oxidation from the outside air. Since the specific components of
manure feedstocks are numerous and varied, it is not clearly
understood what specific chemical reactions may be taking place in
the thermal conversions, and applicants do not wish to be bound by
specific theories or speculation regarding same. However, certain
observations have been made, and the understanding of the following
observations will further enable one skilled in the art in
effectively and efficiently practicing this invention.
[0063] First is the thermal conversion and destruction of
undesirable components, such as organisms, chemicals, etc., as
discussed elsewhere in this disclosure. Second is the thermal
conversion, chemically or physically, of the organic matter (animal
waste, straw, bedding, etc.) in the manure feedstock that makes it
essentially self-binding and enables the thermally treated or
converted feedstock to be made into high physical strength pellets,
granules or prills without the addition of binders or similar
materials. While conventional binders for forming pelletized,
granulated or prilled fertilizers can be used in the practice of
this invention, it is preferred to operate at thermal treatment
temperatures and residence times to produce a material that is
self-binding and can be pelletized/granulated/prilled without added
binders. It is believed that to some extent, when the organic
matter in the feedstock is chemically altered and/or thermally
converted, similar to being "cooked," it transforms ligands,
cellulose, starch, carbohydrates, etc., into materials that can act
as binders in the final product. This provides a binding profile to
enable formation of a final product having particle strengths and
free flowing anticaking and nonfriable properties that make it
useful in conventional dry fertilizer handling and application
equipment. Manure feedstocks that range from very high to very low
proportion of animal waste present can be converted to self-binding
materials that will form good strength pellet, granule or prill
products without additional binders added. Of course, additional
binders may be added to enhance the strength properties of any of
the final products of this invention, if desired. Further, some
materials produced that are low in nutrient value but high in
organic matter and are useful as soil conditioners or soil builders
can similarly be processed to produce usable pellet, granule or
prill products. Third is the recognition that in some operations of
processing a very low moisture content manure feedstock, there may
actually not be any significant drying taking place, i.e., the
moisture content of the feedstock entering the dryer vessel may be
essentially the same as the fertilizer or soil builder material
exiting the dryer vessel, so the dryer vessel is essentially acting
as an oven. In this case, the important processing taking place is
the thermal treatment or conversion and/or chemical alteration
("cooking") of at least a portion of the organic matter present in
the feedstock to enable the produced material to be sufficiently
self-binding to provide a final pellet, granule or prill product
having useful binding, agglomeration, hardness, anticaking,
nonfriable, nondusting, free flowing and humidity tolerant
profiles. Again, optional binders may be added to enhance the
strength characteristics of the final product, if desired.
[0064] The types of dryer vessels that can be used in this
invention are, for example, the following:
[0065] Rotary drum with or without internal scrapers, agitation
plates and/or paddles
[0066] Stationary "porcupine" drum dryer with or without scrapers
and/or agitator plates and/or paddles
[0067] Triple pass stepped drying cylinder or rotary drum dryer
systems with or without scrapers and/or agitator plates and/or
paddles
[0068] Rotary drum dryer systems with or without steam tubes and
with or without scrapers and/or agitator plates and/or paddles
[0069] Turbo-dryer or turbulizer systems
[0070] Conveyor dryer systems with or without scrapers and/or
agitator plates and/or paddles
[0071] Indirect or direct contact dryer systems with or without
scrapers and/or agitator plates and/or paddles
[0072] Tray dryers
[0073] Fluid bed dryers
[0074] Evaporator systems
[0075] Examples of commercially available dryer vessels useful in
or that can be adapted for use in this invention include:
[0076] Scott AST Dryer.TM. Systems
[0077] Simon Dryer Ltd.--Drum dryers
[0078] Wyssmont Turbo Dryer systems
[0079] Duske Engineering Co., Inc.
[0080] Energy Unlimited drying systems
[0081] The Onix Corporation dehydration systems
[0082] International Technology Systems, Inc. direct or indirect
dryer systems
[0083] Pulse Drying Systems, Inc.
[0084] MEC Company dryer systems
[0085] Further examples of dryer vessels useful in or that can be
adapted for use in this invention are disclosed in U.S. Pat. No.
5,746,006 to Duske et al. and U.S. Pat. Nos. 5,570,517 and 6,
367,163 to Luker, the disclosures of which are incorporated herein
by reference in their entirety.
[0086] As noted above the "dryer vessel" does not necessarily
always function primarily as a dryer by removing moisture from the
manure feedstock in the system of this invention. The dryer vessel
also functions as the thermal treatment/conversion/alteration
vessel or oven in which the manure feedstock is heated to
sufficient temperatures for sufficient times to produce the desired
final materials and products as disclosed herein. In addition, the
dryer vessel need not provide direct contact of the turbine exhaust
gases or other heat source and the manure feedstock, but can
provide indirect heating of the manure feedstock to achieve the
drying and/or thermal treatment/conversion/alteration desired
according to this invention. In either direct or indirect heating,
the system is controlled so that no significant oxidation and no
significant pyrolysis of the manure feedstock takes place.
[0087] Another aspect of the dryer vessel adapted for use in this
invention is that the dryer vessel preferably also functions as the
silencer or muffler for the gas turbine or other engine providing
the hot exhaust gases. It is well known that gas turbines,
(essentially jet aircraft engines), produce a high level of noise
impact on the nearby environment. Stationary gas turbines used for
electric power production or other purposes are usually required by
local, state and federal regulations to have silencers installed to
muffle the noise of the exhaust of the gas turbine to acceptable
levels. Such silencers have the economic disadvantages of cost and
creating back pressure on the gas turbine exhaust, which reduces
the efficiency of the gas turbine operation. One advantage provided
by this invention, due to the connection between the gas turbine
exhaust and the dryer vessel being closed to outside air, is that
the dryer vessel functions effectively as a silencer for the gas
turbine. This is at least in part a result of the internal
configuration construction of the dryer vessel acting in
combination with the presence of the high water content manure
feedstock, which combination is effective in absorbing and muffling
the gas turbine exhaust noise. This is also due to the downstream
end of the dryer also being closed to the atmosphere, because the
steam and off gases from the dryer vessel are collected for
condensation, cleaning, recycling and for heat recovery in the
downstream processing in a closed system before being vented to the
atmosphere. It will be apparent to one skilled in the art that
capability for venting at various points in the process and the
equipment system may be desirable to accommodate startup, shutdown,
upset or feedstock variability, but will normally be operated as a
closed system having only final product output and clean exhaust
gas venting. The turbine exhaust optionally can be partially or
temporarily wholly diverted to other downstream units, bypassing
the dryer vessel, when needed for supplemental heat in other
process units or for startup, shut-down or upset.
[0088] Another advantage provided by this invention is that the
steam and off gases can be pulled from the discharge end of the
dryer vessel by an appropriate fan, vent blower, etc., to provide a
reduced pressure at the upstream entrance of the dryer vessel,
thereby reducing the back pressure on the turbine exhaust. This
increases the efficiency of operation of the gas turbine and is
made possible because the connection between the gas turbine
exhaust and the dryer vessel is not open to outside air. It will be
understood that the commercial system design may include a vent or
even a conventional silencer connected by tee or other
configuration into the connection between the gas turbine exhaust
and the dryer vessel for use during startup, shut down or upset
operation, but would not be employed in the normal operating
configuration for the process and apparatus of this invention as
described above. To achieve best efficiency of operation of this
invention, it is preferred that the connection between the gas
turbine exhaust and the dryer vessel inlet have no obstructions in
order to deliver the exhaust gases to the dryer vessel with a
minimum of heat and energy loss between the gas turbine and the
dryer vessel. It will also be recognized from this disclosure, that
the operation of a gas turbine generator will preferably be
controlled for optimal efficiency or economics for the manure
feedstock drying, thermal conversion, chemical alteration and other
processing needs, which may not be the optimal or best gas turbine
operating conditions for electricity production. The electricity
production is a cost recovery revenue stream for the system, but
the overall economics of the operation of this invention may be
better under gas turbine operating conditions that favor optimum
exhaust heat output for efficient dryer vessel operation and
downstream production of products having desired properties and
disfavor electricity production. Determination of such operating
conditions for a particular installation of this invention will be
apparent to one skilled in the art following the teachings herein.
Gas turbine control systems of this type are disclosed in commonly
assigned copending U.S. patent application Ser. No. 10/894,875,
filed on Jul. 19, 2004, the disclosure of which is incorporated
herein by reference in its entirety.
[0089] Another advantage provided by this invention results from
the contact of the gas turbine exhaust gas with the manure
feedstock in the confined space of the dryer vessel without
significant outside air present. The NO.sub.x and SO.sub.x
emissions, and to some extent CO and CO.sub.2 emissions, in the gas
turbine exhaust are substantially reduced, and in some cases
reduced to zero, by absorbing or complexing of the NO.sub.x and
SO.sub.x components into the manure feedstock, where they remain
absorbed, complexed or fixed in the fertilizer material exiting the
dryer vessel and in the fertilizer product after processing into
granular, pellet or prill form. This provides the double advantage
of lowering or eliminating the emissions of NO.sub.x and SO.sub.x
(and CO/CO.sub.2) into the atmosphere and of adding the nitrogen,
sulphur and carbon components to the nutrient value of the
fertilizer produced by the process and apparatus of this
invention.
[0090] The operating conditions and procedures for the dryer vessel
will be apparent to one skilled in the art following the teachings
herein of the disclosure of this invention. The typical turbine
exhaust gas temperature entering the dryer vessel will be in the
range of about 500.degree. F. to about 1,500.degree. F., depending
on moisture and other content of the manure feedstock and the
desired condition of the fertilizer or soil builder material output
from the dryer vessel. In smaller systems with smaller engines, the
inlet exhaust gas temperature can be as low as about 300.degree. F.
or about 350.degree. F. A preferred range is from about 600.degree.
F. to about 1200.degree. F., and it is more preferred that the
inlet temperature be at least about 650.degree. F. and most
preferably at least about 700.degree. F. The temperature and flow
rate of the gas entering the dryer vessel will depend in part on
the moisture content and other properties of the manure feedstock.
Higher moisture content will obviously generally require higher
inlet gas temperatures to reduce the moisture content. It is
believed that an additional efficiency is achieved in the systems
of the present invention where high moisture content manure
feedstock is contacted with high temperature gases. Such contact
causes the formation, sometimes instantly, of superheated steam as
the moisture comes out of the manure feedstock, then that
superheated steam heats and drives the moisture out of adjacent
manure feedstock. It is believed that this mechanism is responsible
for quick drying of the manure feedstock to a low moisture content
so that the remaining residence time of the manure feedstock in the
dryer vessel contributes to the desired thermal
treatment/conversion/alteration or "cooking" thereof according to
this invention. Some manure feedstocks may require lower
temperatures but longer residence time to achieve the conversion or
"cooking" needed to produce a self-binding product having the other
desired properties discussed herein, particularly to meet "organic"
standards. The temperature of the fertilizer or soil builder
material exiting the dryer vessel will typically be in the range of
about 150.degree. F. to about 450.degree. F. and preferably between
about 200.degree. F. and about 350.degree. F. In some operations,
the dryer vessel exit temperature of the fertilizer or soil builder
material should be at least about 175.degree. F. and preferably at
least about 200.degree. F.
[0091] The self-binding properties of the materials and products of
this invention are an important preferred aspect of this invention.
While conventional binders and additives can optionally be used to
provide desired physical strength properties of the granules,
pellets or prills in desired shapes and forms, it is preferred that
the operating conditions should be those that cook and convert the
manure feedstock to produce a self-binding product. Those operating
conditions will depend on the moisture content and the organic
matter content of the manure feedstock that is capable of being
converted to components having binding characteristics. While not
understood and not being bound by any particular theory, it is
believed that starch, protein, carbohydrate and sugar components
are converted to glutenous-like materials that can act as binders
and that oil and ligand-type components are polymerized to act as
binders. In any case, the operating conditions include temperatures
of the exhaust gases, contact time between the manure feedstock and
exhaust gases and the residence time of the manure feedstock solids
in the dryer vessel at elevated temperatures. These conditions will
determine the temperature to which the solids are raised and the
length of time the solids are subjected to the elevated
temperatures. Such temperature may not be a constant temperature
for a particular increment of solids but may be a temperature
profile rising over a period of time to a maximum, then descending
over a period of time or may descend rapidly if the dryer vessel
output is quenched at the exit. Optimum conditions to achieve an
optimum self-binding product can be determined for a particular
manure feedstock following the disclosure herein.
[0092] As used herein the term "fertilizer material" is used to
refer to and means the dried manure feedstock which is produced in
the dryer vessel by reducing the moisture content of the manure
feedstock from an existing level to a lower level according to this
invention and/or achieving the chemical alterations and conversions
referred to herein. The "fertilizer material" is considered an
intermediate product that is suitable for further processing into a
final fertilizer product suitable for consumer, commercial or
industrial use. Typically the fertilizer material from the dryer
vessel will be processed by milling to produce a powder or meal,
followed by granulating, pelletizing or prilling of the powder or
meal to produce the final fertilizer product or soil builder
product suitable for dry application in a crop growing operation.
The fertilizer material can also be milled or otherwise powdered
and made into a slurry or other liquid or pumpable fertilizer
product that can be applied to the soil or in a crop growing
operation in wet form, or pressure applied to hills or cliffs in
remediation or seeding type applications, such as hydro-mulching,
hydro-seeding and hydro-sprigging, or can be used to coat seeds for
such uses or for seed drills or aerial planting. Similarly, the
material the dryer vessel produces may optionally be processed to
form a product similar to natural peat, but typically much higher
(by 20%, 30%, 40%, 50% or 60% or more) in organic matter and lower
in moisture content than natural peat. In the case where the manure
feedstock is partially or mostly bioconverted, the material
produced by the dryer vessel can still be formed into a peat-like
product which is useful as a soil builder product. Even though such
product may not be as high in nutrient value, it will be high in
organic matter, as noted above. The raw output from the dryer
vessel, whether from fresh or bioconverted feedstock, can be the
final fertilizer or soil builder product which can be baled or
packaged in a form desired and suitable for use in various
agricultural and landscape operations. For example, it can be
formed in long "snake" rolls, similar to the straw snake rolls, for
use in erosion control at construction sites. Such rolls made from
the materials of this invention will be just as effective at
erosion control as straw rolls, but due to the higher nutrient
and/or organic matter compared to straw, such rolls will encourage
and enable earlier and more vegetation growth at that site to
resist erosion after the rolls are disintegrated and no longer
effective. The material from the dryer vessel can also be combined
with binders, such as molten urea, to form a product for
agricultural use. As used herein "fertilizer material" and
"fertilizer product" are intended to refer to materials and
products higher in plant usable nutrient values (typically made
from fresh manure feedstock). And, "soil builder material" and
"soil builder products" are intended to refer to materials and
products having lower plant usable nutrient values (typically made
from bioconverted manure feedstock or a feedstock low in manure
content and high in other content such as straw, nesting material,
etc.), but are nevertheless high in organic matter that is
beneficial as a soil conditioner, soil builder or soil amendment.
It is recognized that these materials or products can be blended
with other materials or chemicals as disclosed elsewhere herein. It
is also noted that the products produced by the systems of this
invention, while preferred for fertilizer and soil builder use, can
be used as fuel for heat or electricity production. Local economics
will determine the end use made of the material produced from the
dryer vessel or the final product produced from the system of this
invention.
[0093] As used herein the term "granule," "granulating" and the
like refer to any granular form of the material or product produced
by this invention, including conventional granules, powder, dust,
crumbs and the like, produced by conventional granulation processes
and equipment, including crushing or crumbling previously formed
pellets or prills. The term "pellets," "pelletizing" and the like
refer to any pellet form of the materials or products produced by
this invention, including cylindrical, bullet, spherical or other
shape, typically made by conventional pelletizing processes and
equipment, such as by extruding a slurry or paste and cutting,
chopping, or breaking the extrudate to the desired size. The terms
"prills," "prilling" and the like refer to any prill form of the
materials or products produced by this invention made by
conventional prilling processes and equipment, including spray
tower processes, freeze drying processes, etc.
[0094] An extrusion pelletizer is one of the preferred process
units for use in this invention because it takes advantage of the
self-binding properties of the material produced in the dryer
vessel, and because it can be operated under temperature and
pressure conditions that may further provide or contribute to the
"cooking" of the material to produce the basic and/or enhanced
self-binding properties of the product of this invention. In a
typical operation, the powder or meal from the milling unit may be
mixed with steam or water, for example steam or condensed water
vapor from the dryer vessel, sufficient to form material that is
extrudable at high pressure and temperature to form pellets or
other shapes. The temperatures in the extrusion pellitizer may be
from heated screws, dies or drums or may be from the energy of high
pressure compression. In either case the extrudable material is
heated to a high temperature in the process. It is believed that
for some manure feedstocks that the high temperature and pressure
in the extruder pelletizer may further "cook" or convert certain
components in the material to provide or contribute to additional
or enhanced self-binding properties of the resulting pelletized,
granulated or prilled product. Typical operating conditions for
such an extrusion pelletizer will be an extrudable material having
moisture content of up to about 20% by weight or higher, depending
on the extruder equipment employed. Extruder temperatures and
pressure will be those normally used in conventional extruder
equipment. Other operating conditions can obviously be employed
depending on the manure feedstock being processed and the desired
properties of the formed product. The pellets produced may be dried
to reduce the moisture content to a level suitable for stable
product storage, e.g., about 10% by weight. The moisture removed at
this point in the process can be recycled for use in other steps
and processes of the systems of this invention, as disclosed
herein.
[0095] The manure feedstock will typically have a moisture content
between about 50% and about 90% by weight, preferably between about
60% and about 80% by weight and most preferably between about 65%
and about 75% by weight. (Percent by weight, as used herein, is in
reference to percent of the component in question based on the
total weight of the mixture referred to.) Although manure feedstock
of lower moisture content, for example, as low as about 40% by
weight or even about 30% by weight can be processed in this
invention. The preferred manure feedstock has a moisture content of
at least about 50% by weight, more preferably at least about 60%
and most preferably at least about 70% by weight. When the manure
feedstock has a high moisture content in this range, processing
advantages are achieved from the essentially instant production of
steam and superheated steam at the inlet of the dryer vessel where
the 1,000.degree. F. exhaust gases contact the high moisture manure
feedstock at atmospheric or subatmospheric pressure. The steam and
superheated steam thus produced contributes to the drying, cooking
and conversion of adjacent or nearby and downstream particles of
manure feedstock, which enhances the efficiency of the process. It
is preferred for operation of the process and apparatus of this
invention that the manure feedstock be mixed and blended among
batches or different parts (top, bottom, indoor, outdoor, etc.) of
the same batches to provide a uniformity of manure feedstock
properties. This preferred preparation enables the production of a
more uniform fertilizer material from the dryer vessel, and
simplifies control of the process operations. The temperature of
the manure feedstock will typically be ambient, i.e., in the range
of about 30.degree. F. to about 100.degree. F., but can be lower
than 30.degree. F., provided that any frozen agglomerations do not
interfere with the feedstock preparation or the operation of the
dryer vessel and feedstock feeder equipment. While manure feedstock
is preferred to be at a low temperature to reduce or prevent
composting or bioconversion of nutrients before processing
according to this invention, it may be advantageous for process
economics or for throughput capacity to preheat the manure
feedstock prior to introduction into the dryer vessel. If
preheating is used, it preferably is done just before use in this
invention so composting and bioconversion are kept to a minimum. If
such feedstock preheating is employed, it may be done in any
desired fashion, such as heat exchanger, solar heating, heated
conveyers or augers or heated concrete slabs in the staging and
feedstock preparation area.
[0096] The contact time between the turbine exhaust gases and the
manure feedstock will be determined by several variables including
moisture content of the feedstock, moisture content desired in the
dryer vessel output material, the chemical alteration/conversion
desired, volume and temperature of the exhaust gases entering the
dryer vessel and other factors. The contact time will be regulated
to provide not only the drying desired, but also to elevate the
particles of manure feedstock solids to sufficiently high
temperatures to sufficiently destroy or convert to harmless forms,
the undesirable components present in the feedstock, such as
organisms, microorganisms, seeds, pesticides, antibiotics,
hormones, prions, viruses and the like, when such conversion or
destruction is desired, and to produce a self-binding product, when
desired. The actual temperature attained by the particles is not
important to determine, so long as the desired levels of said
component destruction and conversion and the desired level of
self-binding are achieved. The desired contact time can be varied
and regulated by the dryer vessel volume and size and by the
throughput volumes of the feedstock and exhaust gases. The heat
transfer from the exhaust gases to the feedstock, and consequently
the temperature to which the feedstock is heated, will mainly be a
function of the mass ratio of exhaust gas to feedstock. An example
of the dryer vessel operation with a gas turbine generator is a
Rolls Royce Allison 501-KB5 generator (rated at 3.9 MW) having an
exhaust gas output of about 122,000 lb./hr. at 1,000.degree. F. and
connected to a Scott Equipment Company, New Prague, Minn., USA
rotary tubular dryer model AST 8424 having an internal volume of
about 26 cubic meters (m.sup.3). The manure feedstock is a fresh
cattle feedlot manure having a moisture content of about 70% by
weight and a temperature of about 65.degree. F. is fed to the dryer
vessel at a rate of about 6,500 kg./hr., which is about 10
m.sup.3/hr., (about 16,200 lb./hr.) to provide an average or
nominal residence time of the solids in the dryer vessel of about
10 to about 18 minutes and a weight ratio of exhaust gases to
manure feedstock of about 7.5. The dryer vessel output is at about
200.degree. F. The weight ratio of exhaust gas to feedstock will
generally be between about 15:1 and about 1:1, preferably between
about 10:1 and about 3:1 and more preferably between about 8:1 and
about 4:1. The heat requirement may call for a ratio of at least
about 20:1 or at least about 25:1 or higher where the feedstock is
cold with a very high moisture content and the exhaust gas is not
at a high or maximum temperature. The exhaust gas flow and the
manure feedstock flow through the dryer vessel may be concurrent,
countercurrent, single stage, multiple stage, etc., depending on
results desired and various system designs and economic
considerations.
[0097] The output from the dryer vessel comprises steam, water
vapor, combustion gases and solids that are dried and/or thermally
treated and converted to desired forms. Typical dryer vessel outlet
temperatures of the gases and/or solids will normally range from
about 200.degree. F. to about 350.degree. F., but lower or higher
temperatures may be selected and/or desired for economic, product
quality and/or process efficiency reasons. The outlet temperatures
can be from at least about 110.degree. F. to at least about
500.degree. F., preferably at least about 180.degree. F. and more
preferably at least about 200.degree. F. It is generally desired
that the solids material exiting the dryer vessel will generally
have a moisture content between about 10% and about 15% by weight,
but can range from about 5% to about 25% by weight. Again, lower or
higher moisture content of the dryer vessel output solids may be
selected and/or desired for similar reasons. The steam, water vapor
and combustion gases exiting the dryer vessel will normally be
routed through heat exchangers (for recovery of process heat usable
downstream in granulating or pelletizing operations or upstream in
feedstock or turbine intake air preheating), condensers (for
recovery of process water for upstream or downstream use, for
agricultural application or for disposal), scrubbers, filters or
cyclones (for recovering solids entrained in gases or liquids and
rendering gases and liquids environmentally acceptable for release)
and other conventional process equipment.
[0098] The solids output from the dryer vessel is referred to
herein as fertilizer or soil builder material, which solids are
typically further processed by milling, granulating, pelletizing,
prilling or other processing to produce a final fertilizer or soil
builder product in the form desired for final packaging or for bulk
distribution. Such milling, granulating, pelletizing or prilling
equipment and operations useful in this invention are those that
are conventional and well-known, since the output from the dryer
vessel comprises solid and vapor components that lend themselves to
such processing. The dryer vessel solids output can be referred to
herein as the fertilizer or soil builder product when used in its
raw form for crop application without further processing into
powder, granular, pellet or prill form. The dryer vessel output is
referred to as a soil conditioner material or product when the
manure feedstock is of a type that produces a material having low
nutrient value as a fertilizer, but is nevertheless useful as a
soil builder or conditioner having high organic matter content,
similar to a peat type product, or may be a combination of
fertilizer and organic matter soil builder product. Whatever the
product in whatever form, the process, system and equipment of this
invention provide for environmentally and economically effective
processing of manure feedstocks to remove them as environmental
liabilities and provide products which are useful to improve soil
conditions, sequester carbon in the soils or other environmentally
advantageous applications, and to eliminate disposal in a
landfill.
[0099] This invention can be used to produce a variety of products
and materials from manure feedstocks, but the preferred materials
and products are those that have no significant undesirable
components remaining that have not been converted or destroyed in
the heating, chemically altering and/or drying treatment in the
dryer vessel or other operations. The products and materials
produced by this invention are preferred to be useful fertilizer or
soil builder products, but this invention is also useful in
producing reduced-volume solids for disposal in landfill with the
advantage of providing solids having low levels or no amounts of
harmful components to leach out from the landfill into surface or
ground water.
[0100] The products and materials produced by this invention are
useful for and include blends with other materials, products or
chemicals, as may be desired for particular end uses requiring
particular properties or characteristics. Such other materials and
additives can be added and blended at any appropriate point in the
process: blended with the manure feedstock, added to the dryer
vessel, added in the process water at any point, added to the
material exiting the dryer vessel, added as part of any milling,
granulating or pelletizing processing or simply mixed with the
final product or blended in before bagging or packaging or at the
point of use. For example the fertilizer and soil builder products,
while usually relatively odor free, can be blended with other
materials that can either provide a pleasant odor or mask any
unpleasant odor. Such materials can be synthetic (perfumes) or
natural, with natural materials being preferred. Natural, organic
materials can include sage, mint, fennel, garlic, rosemary, pine,
citrus and similar materials that would not prevent certification
as an organic input. Other materials for blending can include iron,
minerals, carbon, zeolite, perlite, chemical fertilizers (urea,
ammonium nitrate, etc.), pesticides and other materials to adapt
the fertilizer or soil builder product for specialized use.
Although certified organic products are the most preferred products
of this invention, the products of this invention can include any
conventional NPK fertilizer blend or mixture in any conventional
form, including extended release forms. For example, the fertilizer
products of this invention may include added herbicides (for
typical "weed and feed" products) and other additives that may be
organic based or chemical that may or may not qualify for certified
organic status. It is well known in the art to make fertilizer
products in desired granule or particle size having desired
hardness and integrity in dry form, but readily dispensable when
applied to an agricultural operation and treated with water by
irrigation or rainfall. For example, see U.S. Pat. No. 4,997,469 to
Moore and U.S. Pat. No. 5,676,729 to Elrod et al., the disclosures
of which are incorporated by reference in their entirety.
[0101] In some cases, a product can be granted organic
certification provided the levels of man-made components, including
genetically modified organisms, chemical fertilizers, other
materials that are not organic, etc., in the final product are
typically below about 5% by weight or in other cases for "natural"
labeling, below about 30% by weight. On the other hand inputs into
organic fertilizers and organic soil builder products can contain
essentially no detectable amounts of other materials identified as
undesirable components, such as undesired organisms and
microorganisms (including genetically modified organisms),
pathogens, viable seeds, pesticides (including insecticides,
herbicides, algicides, rodent poisons, etc.), antibiotics,
hormones, prions or viruses. However, in other cases the product
will qualify for organic certification even if certain of these
undesirable components in the final product are detectable but are
below a specified level. As used herein "microorganism" is used to
include bacteria, protozoa, fungi and algae. However, it will be
recognized that not all microorganisms are undesirable in a
fertilizer or soil builder product, even in certified organic
products, but certain microorganisms are undesirable and are to be
destroyed, inactivated, killed or otherwise converted to harmless
forms by the thermal treatment according to this invention, such as
pathogenic bacteria. Since the standards set by the various
agencies for organic products differ somewhat and are changed
periodically, it is not practical to set forth the details here. It
is important to note, however, that when a product is selected for
production in the system of this invention, the operating
conditions of the processes of this invention can be varied over
wide ranges and selected to provide the conversions and
purifications needed to meet the applicable standards and produce
products that can be certified organic.
[0102] The systems of this invention include configurations that
can be used to reduce and in some operations essentially eliminate
the emission into the atmosphere of noxious odors and greenhouse
gases from animal feeding operations and from municipal sewage
facilities. As noted above, in addition to bioconversion of animal
waste, one of the major sources of greenhouse gases (methane in
particular) and noxious odors is from the gases produced in the
enteric fermentation in the animals themselves and the release of
those gases by the animals by eructation, emission of flatulence
and the essentially immediate release of those gases from urine and
feces upon evacuation from the animals, referred to herein as
"animal gases." Animal feeding operations are coming under
increasing regulation by federal and state agencies due to
increasing pressure from population areas near the animal feeding
operations. The regulation is directed to two aspects of air
quality. The first is noxious odors from animal gases and
bioconversion emissions, which contain mercaptans and many other
organic compounds that have offensive odors and which are
objectionable to residential communities. The second is greenhouse
gas emissions that are harmful to air quality. Greenhouse gases
include CO.sub.2, CH.sub.4, and N.sub.2O and are usually referred
to in terms of CO.sub.2 equivalent effect on the atmosphere.
Methane has a CO.sub.2 equivalent factor of about 23 (as used by
the USDOE), which means that 1 kg of CH.sub.4 released into the
atmosphere is equivalent to 23 kg of CO.sub.2 released. (Some
sources give the equivalent factor as about 21.) In the United
States Department of Energy/Energy Information Administration
Report # DOE/EIA-0573 (2002) released October 2003 (available at
www.eia.doe.gov/oiaf/1605/gpt/) it is estimated that 8 million MT
of CH.sub.4 (183 million MT CO.sub.2 equiv.) was released into the
atmosphere in 2002 by agricultural operations, which was about 30%
of all CH.sub.4 emissions in the U.S., the other sources including
landfill and municipal sewage treatment operations. Of the
agricultural CH.sub.4 emissions, 94% was from livestock operations,
of which 67% (about 5 million MT) was from enteric fermentation
(animal gases) and 33% (about 3 million MT) was from decomposition
of livestock wastes. While CH.sub.4 is the main greenhouse gas
produced by bioconversion of manure, CO.sub.2 and NO.sub.x gases
are also produced. It is particularly desired to prevent NO.sub.x
release into the atmosphere, because it is estimated that it has a
CO.sub.2 equivalent of about 310. This invention can be used, as
disclosed herein, to essentially eliminate atmospheric release of
animal gases and essentially eliminate the decomposition greenhouse
gas emissions from animal feeding operations by containing and
processing the animal gases, by processing the manure feedstock to
prevent decomposition or bioconversion taking place and/or
containing and processing emissions from decomposition or
bioconversion that takes place before the manure feedstock can be
processed.
[0103] The systems of this invention are particularly useful in
essentially eliminating the animal gas emissions and odors from
animal gases in certain existing animal feeding operations. Other
animal feeding operations can be easily modified according to the
disclosure herein to utilize the systems of this invention to
reduce or eliminate release of animal gases and associated odors
into the open atmosphere. In the basic system of this invention,
the gas turbine exhaust is connected to the dryer vessel. To
control animal gases produced in an animal feeding operation, the
gas turbine air intake is connected to the animal shelter
ventilation system so that the ventilation air exhausted from the
animal shelter is directed into the gas turbine air intake where
two processes normally will take place. First, the animal gases are
burned along with the regular fuel supply, thereby converting the
CH.sub.4 to H.sub.2O and CO.sub.2 and converting the mercaptans and
other noxious or acrid compounds to H.sub.2O, CO.sub.x, NO.sub.x
and SO.sub.x. Second, the exhaust gases from the gas turbine are
contacted with the manure feedstock, where the NO.sub.x and
SO.sub.x and to some extent COX gases are absorbed into or
complexed with the manure feedstock as it is dried and/or converted
to a fertilizer or soil builder material, and preferably to a
self-binding fertilizer or soil builder product. This aspect of
this invention prevents the animal gases from entering the
atmosphere.
[0104] The existing animal feeding operations that can immediately
directly and efficiently utilize this invention for control of
animal gases are those that are normally completely enclosed and
ventilated by fresh air inlets and exhaust air outlets, and
particularly those that are climate controlled by heating and air
conditioning. The climate controlled animal feeding operations are
typically the chicken and hog operations, although some dairy,
veal, beef and other operations are enclosed and climate controlled
due to extreme heat or cold in the local climate. The exhaust air
from such facilities is directed to the gas turbine combustion air
inlet. Other animal feeding operations that have free-stall or open
barn structures can take advantage of this invention by pulling
vent air from the top of the structure and ducting it into the
turbine air inlet. This will capture a significant portion of the
animal gas, particularly on zero wind days, because the methane in
animal gases is lighter than air and will rise to the top of the
structure. In addition, such structures can be economically
enclosed (e.g. by canvas walls) and ventilated by forced air (with
or without climate control) to collect essentially all the animal
gases from the animals in the structure and directing the exhaust
vent air to the gas turbine air intake.
[0105] In utilizing this aspect of this invention it will be
recognized that it is preferably operated so that all the
ventilation air exhausted from the hog barn, chicken house, etc. is
fed to the gas turbine air intake to prevent release of animal
gases to the atmosphere. Any remaining combustion air needed for
the gas turbine will be from ambient air through a conventional air
filter, although it is preferred that the animal barn exhaust vent
air also pass through the gas turbine intake air filter to prevent
damage or erosion of turbine components by entrained dust or other
particles. The solids collected in the air filter can be fed to the
dryer vessel or to other process units in the system for
incorporation into the final fertilizer or soil builder product.
Although the methane in the animal gases will not normally
constitute a significant portion of the fuel requirements of the
system, it is burned to produce heat and is not released to the
atmosphere. Nevertheless, every kg of animal gas methane burned
reduces the outside methane fuel requirement by one kg and reduces
greenhouse gas emissions by CO.sub.2 equivalent of 23 kg. This
aspect of the invention also provides the benefit of turbine inlet
noise control. Similar to the dryer vessel acting as a silencer for
the turbine exhaust, having the turbine inlet enclosed and air
ducted in a closed system from the animal barn substantially
contains and muffles the high frequency turbine inlet noise.
[0106] It will also be recognized that, while the above description
is in terms of using a gas turbine, the same utilization of this
aspect of this invention to control animal gas emissions can be
made using whatever heat source is selected for use in the system.
Whether the heat source is a gas turbine, gas turbine generator,
reciprocating gas or diesel engine or even a conventional oil or
gas burner (like 107 in FIG. 1), the animal shelter exhaust vent
air can be directed to the combustion air intake so the animal
gases are burned and preferably so the combustion gases are
contacted with the manure feedstock.
[0107] As further disclosure and illustration of the processes,
systems and equipment of this invention, reference is made to the
schematic flow chart of FIG. 1. In the exemplary process
illustrated, gas turbine generator unit 100 comprises gas turbine
101 and electric generator 102. The gas turbine has air intake
filter 104 (which can optionally include animal shelter ventilation
air, such as 903 in FIG. 5) and fuel feed 103. If desired, optional
bypass exhaust silencer 106 can be included for startup, shutdown
or upset conditions during those times the gas turbine is running
but the exhaust gases cannot be directed into the dryer vessel.
However, dryer vessel 200 will function as the silencer in the
normal operation of the system of this invention. Alternatively,
instead of silencer 106, the exhaust gas bypass (see 908 in FIG. 5)
around the dryer vessel can be directed to any appropriate
downstream unit, such as separator 208 and/or separator 600, which
can provide a temporary silencer function. This arrangement
eliminates the cost of a separate silencer and the space required
for a separate silencer, which is an important consideration for
the portable, truck-mounted systems. The gas turbine 101 exhaust is
connected to the dryer vessel 200 by connector 105. An optional air
inlet (not shown) can be included for dryer vessel 200 in connector
105 or elsewhere for purging the dryer vessel or the system, for
startup or shutdown or for other reasons, particularly when either
the exhaust gases or the manure feedstock is not present in the
dryer vessel 200. However, when both are present, any such air
inlet is closed and not used in order to substantially preclude
introduction of air into the dryer vessel and to preclude
significant oxidation of materials being processed in the dryer
vessel 200. Optional burner 107 can also be included to provide
supplemental heat source and combustion gases for the dryer vessel,
which can be provided for input in connector 105 or elsewhere. The
optional supplemental heat source may be useful during startup,
shutdown, process upset, turbine outage or to maintain desired
throughput when a peak load or unusually high water content
feedstock is encountered.
[0108] The manure feedstock is typically introduced into the system
by mechanical means, such as a front end loader 201, which drops
the feedstock into a rock separator, mixer, chopper unit 202. The
feedstock can be further mixed and foreign objects separated in
screw conveyers 203, 204 then fed to the dryer vessel 200 through
215. The feedstock can also be pre-mixed or conditioned for desired
uniformity prior to loading into this system by loader 201, e.g.,
in storage windrows that can be combined and mixed.
[0109] The output from the dryer vessel 200 is transferred by
conduits 205, 206 to separator 208 where the solids and gases are
separated. The gases pass through 209 and blower 210 to the
atmosphere via 211 or to other downstream processing via 212.
Blower 210 can be operated to lower the pressure in separator 208
and in the dryer vessel 200, which will reduce the water boiling
point in the dryer vessel and will reduce the water boiling point
in the dryer vessel and will reduce the backpressure on the turbine
exhaust and increase the turbine output and efficiency.
Alternatively, blower 210 can be operated to maintain increased
pressure in dryer vessel for higher temperature treatment,
conversion or "cooking" of the manure feedstock, if desired. The
output from dryer vessel 200 can pass through optional heat
exchanger 207 for recovery of process heat for use downstream or in
preheating the manure feedstock or turbine intake air. The solids
output from separator 208 pass to ball mill or hammer mill 300 via
conduit, conveyor or auger 301 and optional mixers and conditioners
302 and 303. In addition, recycled solids, such as fines, from
recycle loop 305 can be mixed in at 303 via 304 to be combined for
feeding to the ball mill or hammer mill 300. The fines and off spec
material generated at various points in the system can be collected
and recycled via loop 305 and reintroduced into the product
processing system at any desired point for further processing, such
as the milling unit 300 via 304, the pelletizing unit 400 via 404
or even the manure feedstock preparation 202, 203, 204 or other
points. An important capability of the system of this invention is
the complete recycle via recycle loop 305 of all fines or off spec
solids so that they are eventually incorporated in the final
products. Thus, the system of this invention provides 100%
conversion of the manure feedstock solids (except for rocks and
other foreign objects that are not processible) into the fertilizer
or soil builder products and does not produce a solids waste stream
that must be otherwise disposed of, such as in a landfill.
[0110] The ball mill or hammer mill 300 is used to produce a
uniform small particle size, short fiber length material called
"meal" which is suitable for processing in pelletizer unit 400 to
provide a product that has sufficient hardness and mechanical
durability and stability for the conventional processing, packaging
and storage normally used for dry fertilizer products. The output
of ball mill or hammer mill 300 goes through separator 310 where
vapors are taken off and sent via 315 to separator 600 for recycle
of solids via recycle loop 305 and venting of vapors to the
atmosphere via blower 601 and vent 602. Separator 310 takes out
fines or material suitable for recycle via recycle loop 305 and
passes the meal to mixer 311. The meal is then sent via 312 to
separator 401 and either direct to pelletizer 400 via 408 or to
holding or surge bin 402 via 409a and 409b for mixing with other
materials, recycle materials from 404 or additives or for holding
in case of process startup, shutdown or upset. From surge bin 402
the meal is sent through mixer 403 and either directly to the
pelletizer unit 400 via 417 or to mixer 311 via 412 for mixing with
fresh meal when desired.
[0111] The pellets from pelletizer 400 are passed through heat
exchanger, vapor removal unit 405 and from there sent via 406 and
414 either direct to final product cleaning in units 407 and 415
and finished product shipping or storage bin 500 via 416a, 416b,
501 and 503, or sent via 413 and surge bin 410 to a crumbler or
granulator unit 411 then to final product cleaning units 407 and
415. The final product is loaded in truck 502 via 501, 503 or via
storage bin 500 for transport to market. The fines and off spec
product separated out in final cleaning unit 415 can be recycled
for reprocessing via recycle loop 305. The crumbler or granulator
411 converts the pellets to smaller particle or granular size
having essentially the same hardness and mechanical durability and
stability as the pellets. The solids can be transported between
processing units of this invention by conventional augers,
elevators, conveyor belts, pneumatic tube conveyors and the like,
as appropriate for the material and for environmental
considerations. As is apparent, the system can be designed and
configured to produce a fertilizer material or soil builder product
from dryer vessel 200 (that can be baled for direct use), meal from
mill unit 300 (that can be bagged for later processing or for
direct use) or a granular product, a pellet product or a prill
product from 415.
[0112] An example of the operation of the system according to this
invention can be seen from the following table. This example is
based on the use of a Rolls Royce Allison 501-KB5 (rated at 3.9 MW)
gas turbine generator and a Scott Equipment Co. dryer model AST
8424 processing fresh cattle manure at a feedlot operation.
TABLE-US-00001 Example of System Sized for Nominal 2.5 Metric
Tons/Hr Finished Product Stream No. Component Flow Rate Condition
103 Natural Gas 820 kg/hr Ambient Temp. 104 Combustion Air 48,140
kg/hr Ambient Temp. 105 Exhaust Gases 48,960 kg/hr 1,200.degree. F.
215 Manure Feedstock 6,500 kg/hr 70% H.sub.2O/ Ambient Temp. 200
Residence Time 10-18 min. 301 Dried Material 2,730 kg/hr 12%
H.sub.2O by wt. 200.degree. F. 312 Meal 2,500 kg/hr 10% H.sub.2O by
wt. 125.degree. F. 503 Pelletized Fertilizer 2,500 kg/hr 12%
H.sub.2O by wt. Product 15.degree. F. above Ambient Temp.
[0113] FIG. 2 illustrates one configuration of the system of this
invention in the form of skid-mounted, truck mounted or rail car
mounted units that can be transported to and operated at desired
agricultural or municipal operation sites where manure feedstock is
available on a daily or periodic basis. The first unit 700
comprises the gas turbine 101 and generator 102. The second unit
701 comprises dryer vessel 200 and separator 208. The dryer vessel
200 has manure feedstock inlet 215 and is connected to the gas
turbine exhaust by connector 105 when stationary and in operation.
The third unit 702 comprises the processing equipment desired for a
particular operation, such as the ball mill and pelletizer. The
product output is conveyed by 501 to storage units 500 or to truck
502 for transport to market. Optional equipment can also include
units for bagging and other packaging of the final product for
various markets.
[0114] FIG. 3 is an illustration of the same units as in FIG. 2,
but positioned on the operation site in a different configuration.
It is apparent that the portable, truck-mounted units of this
invention are adaptable to a variety of sites that may have
limitations on space available.
[0115] FIG. 4A is a plan view and FIG. 4B is an elevation view of
another portable configuration of the system of this invention
wherein all operating units are mounted on a single semitrailer
truck 800a and 800b. Gas turbine unit 100 exhaust is connected to
dryer vessel 200 by connector 105. Dryer vessel 200 has manure
feedstock inlet 215 and is connected to separator 208 by conduit
206. Separator 208 is connected to vapor/air cleaner separator 600
by conduit 209 and separator 600 vents to the atmosphere by vent
602. The bottom outlet of separator 208 is connected via conduit
301 to ball mill unit 300. The outlet of ball mill unit 300 is
connected via conduit 312 to pelletizer unit 400, which is
connected to product cleaning unit 415 by conduit 414. Cleaning
unit 415 has product outlet 416. Not shown in FIGS. 2, 3 and 4 is
an optional enclosure for each skid-mounted or truck-mounted unit
to enclose the entire unit for weather protection and for noise
attenuation.
[0116] FIG. 5 is a schematic process flow chart of some of the
optional systems of this invention. In a preferred operation of
this invention, animal barns 900 and manure pits 901 are enclosed
and ventilated with fresh air 902. The ventilation air 903 from the
animal barns is fed to the gas turbine 101 as part of the
combustion air feed 904 through air filter 104. The manure pits 901
can be within the same barn enclosure or can be separate holding
tanks or lagoons that are enclosed so that all vapors given off by
the manure can be contained and passed to the gas turbine 101 along
with the barn ventilation air 903 for combustion along with the
conventional fuel 103, such as locally available natural gas. This
prevents greenhouse and noxious or acrid gases from the animals and
the manure from being released into the atmosphere, including
biogases from any bioconversion that takes place before the manure
can be processed in the system of this invention. Not only does
this provide the opportunity for commercial use of this invention
to obtain air quality credits for reduced greenhouse gas emissions,
it also provides animal feeding operations a way to become
acceptable neighbors with nearby residential areas, because all
noxious and acrid odors from the animals and the manure can be
contained within the system and incorporated in the final
fertilizer product or converted to components that are not noxious
or acrid before venting to the atmosphere. As noted above in the
DOE/EIA Report, the total methane given off by a livestock feeding
operation, about two thirds is from enteric fermentation (animal
gases) and about one third is biogas from bioconversion of manure.
Thus, in conventional biogas operations that use as fuel the
methane from bioconversion of manure, two thirds of the methane
from the livestock feeding operation is released into the
atmosphere in the animal gases, while only the one-third from
bioconversion is contained and utilized. In contrast, use of this
aspect of this invention not only prevents the formation of the
methane in biogas because this invention substantially prevents
bioconversion and retains all the nutrient values from the manure
in the fertilizer product, but also contains and utilizes most or
all of the other two-thirds methane in the animal gases as fuel and
converts all other noxious and acrid gases from a livestock feeding
operation to other compounds which are either absorbed or complexed
in the fertilizer product or are not objectionable for release to
the atmosphere.
[0117] The gas turbine generator 101/102 produces electric power
905, which can be either sold to the local power company 906 or
distributed by 907 for use in the animal feeding operation or the
processing units in the systems of this invention. Some animal
feeding operations will find that the cost of enclosing an open
animal barn and installing and operating heating and air
conditioning climate control in order to contain and process all
greenhouse gases via 903 can be at least partially if not
substantially off set by using the electricity 905 for operation of
the climate control system. For example, it may be feasible, or
necessary in some instances due to governmental regulation, to
cover a normally open feedlot or dairy operation with inflatable
tents, similar to those used for tennis courts, to provide
economical systems for containing and collecting all animal gases
from such an operation, so those gases can be processed via 903
according to this invention. The economics of each commercial
operation, fuel costs, selling price/purchase price of electricity
and capital cost of equipment will determine whether the
electricity is used internally in the animal feeding operation,
sold to the power company, used in other nearby operations or any
combination thereof.
[0118] The exhaust gases from the gas turbine 101 are passed to
dryer vessel 200 by a connection 105 that precludes outside air
from entering the dryer vessel. As disclosed herein, the system is
operated so that the oxidation of the manure feedstock in the dryer
vessel 200 and elsewhere in the system is minimized and
substantially avoided. The dryer vessel 200 also serves as silencer
for the gas turbine. An optional bypass 908 can be provided so the
exhaust gases can be sent to downstream equipment, such as
separators/condensers 208, to silence the gas turbine exhaust when
the dryer vessel is off line and to clean the exhaust gases before
release into the atmosphere during such temporary operation. Or,
the bypass 908 exhaust gases can be sent to a heat exchanger for
water heating, animal shelter heating or other climate control or
process energy requirements. This bypass eliminates the cost of
having a separate silencer to satisfy noise restrictions on the gas
turbine when the dryer vessel is off line and provides a more
compact design for portable or truck mounted units.
[0119] Manure feedstock 215 is fed to the dryer vessel 200 along
with the exhaust gases from connection 105 and any auxiliary heat
provided from alternate or auxiliary heat source 107. The manure
feedstock preferable comes directly from the manure pits 901 in
animal barns 900 so it is fresh and has little or no time for
bioconversion. Other manure feedstock sources 910 can be used or
included in the system, such as stockpiled manure or manure from
other operations that is brought in to be combined or mixed with
the manure from the immediate animal barn. As disclosed herein,
other green waste, organic materials, inorganic materials or
additives can be combined with the manure for processing in the
system of this invention.
[0120] The output from dryer vessel 200 is sent via 205 to the
separators/condensers designed to separate the solids 912 for
further processing downstream, to condense the water vapors as
reclaimed water 913 and to clean the gases 914 vented to the
atmosphere. The reclaimed water can be used downstream as process
water, recycled for use in preparing or conditioning the manure
feedstock, used for livestock water or used for crop irrigation.
The solids output 912 from the separator units 208 is normally
further processed by milling, pelletizing, granulating, bagging,
etc. However, the solids 912 can be used as an intermediate to form
other types of products. For example, it can be baled for use much
like a peat material, it can be formed into bricks, rolls and other
shapes for use in erosion prevention much like straw rolls are used
(but having higher nutrient or soil builder value than straw), it
can be used alone or in combination with other materials for
incineration to utilize the fuel value of the material, it can be
used in a bioconversion system to produce a methane or biogas fuel,
it can be used as an animal feed, or it can be stored for any
desired use or further processing at a later time. Similarly the
meal/powder output 914 from the milling operation is normally
further processed by pelletizing, granulating, etc., but can be
used as an intermediate to form other types of products, such as
slurry for spray application, hydro-mulching, etc. The final
product 915 is preferred for use as a fertilizer, but is also
useful as above for the intermediate products.
[0121] In each of the downstream operations, water vapor may be
recovered and recycled to the separators/condensers 208 for reuse.
As is apparent, the systems of this invention are adaptable to
various configurations and various designs depending on the
processing needs and economics of particular animal feeding
operations. Various conventional heat recovery and recycle aspects,
not shown in FIG. 5, can be designed into commercial installation
of the systems of this invention by using ordinary process
engineering design skills, including the fines recycle 305 shown in
FIG. 1, use of gas/vapor stream 914 for various heat recovery and
pre-heating applications, insertion of binders, additives and
blending materials at various desired points in the system, cooling
the combustion air and/or animal barn ventilation air, e.g., by
water spray, to increase efficiency and power output of the gas
turbines, dewatering very high water content manure feedstock, etc.
The final pelletized, granulated or prilled product 915 can be
bagged or shipped bulk for conventional end use applications.
[0122] As will be apparent to one skilled in the art, multiple gas
turbines, other engines and/or burners of the same or varying types
and sizes can be manifolded together to feed multiple dryer vessels
of the same or varying types and sizes in a single installation.
This can be done to not only provide increased feedstock processing
capacity but also to provide operational flexibility for processing
varying feedstock loads and for performing equipment maintenance
without shutting down the operation.
[0123] While we have illustrated and described various embodiments
of this invention, these are by way of illustration only and
various changes and modifications may be made within the
contemplation of this invention and within the scope of the
following claims.
* * * * *
References