U.S. patent application number 12/316120 was filed with the patent office on 2009-10-15 for process and system for drying and heat treating materials.
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 | 20090255144 12/316120 |
Document ID | / |
Family ID | 35597896 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090255144 |
Kind Code |
A1 |
Gorbell; Brian N. ; et
al. |
October 15, 2009 |
Process and system for drying and heat treating materials
Abstract
This invention discloses systems and methods for conversion of
high moisture waste materials to dry or low moisture products for
recycle or reuse. 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 and wherein the processing unit forms
the dried material from the dryer vessel into granules, pellets or
other desired form for the final product. Optionally, the systems
and methods further provide for processing ventilation air from
manufacturing facilities to reduce emissions therefrom.
Inventors: |
Gorbell; Brian N.; (US)
; Carin; Christianne; (Priddis, CA) ; Fedkenheuer;
Alvin W.; (Calgary, CA) ; Jonasson; John S.;
(Tisdale, CA) ; Starosud; Alexander; (Calgary,
CA) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
EarthRenew, Inc.
Half Moon Bay
CA
|
Family ID: |
35597896 |
Appl. No.: |
12/316120 |
Filed: |
December 8, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11399765 |
Apr 7, 2006 |
7487601 |
|
|
12316120 |
|
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|
10895030 |
Jul 19, 2004 |
7024800 |
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11399765 |
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Current U.S.
Class: |
34/385 |
Current CPC
Class: |
Y02P 70/10 20151101;
F26B 2200/18 20130101; Y02P 70/405 20151101; F26B 19/005 20130101;
F26B 23/02 20130101; Y02E 20/12 20130101; Y02E 50/30 20130101; Y02E
50/12 20130101; Y02E 50/10 20130101; F26B 23/001 20130101 |
Class at
Publication: |
34/385 |
International
Class: |
F26B 7/00 20060101
F26B007/00 |
Claims
1. A method for treatment of waste material feedstock comprising:
operating a gas turbine generator to produce electricity and
exhaust gases having a temperature greater than 700.degree. F.;
contacting the exhaust gases having a temperature greater than
700.degree. F. directly with waste material feedstock in a dryer
vessel for a contact time sufficient to produce a dried material
having a moisture content of less than about 20% by weight;
outletting the exhaust gases and the dried material from the dryer
vessel through a dryer outlet; conveying the exhaust gases and the
dried material together through a dryer outlet conduit that extends
from the dryer outlet to a solids/gas separator; drawing the
exhaust gases from the solids/gas separator using an air moving
device in fluid communication with the solids/gas separator,
wherein the air moving device also reduces backpressure in the
dryer vessel by drawing the exhaust gases from the dryer vessel
through the dryer outlet conduit to the solids/gas separator.
2. A method according to claim 1 wherein the exhaust gas contacting
the waste material feedstock is at an initial temperature between
about 1,100.degree. F. and about 1,600.degree. F.
3. A method according to claim 1 wherein the waste material
feedstock comprises at least about 30% by weight moisture.
4. A method according to claim 1 further comprising the steps of
granulating, pelletizing or prilling the dried material to produce
a product suitable for conventional dry product handling, transport
or use.
5. A method for producing a dried material from an inorganic waste
material feedstock comprising: operating a gas turbine generator to
produce electricity and exhaust gases having a temperature greater
than 700.degree. F.; contacting the exhaust gases having a
temperature greater than 700.degree. F. directly with waste
material feedstock in a dryer vessel for a contact time sufficient
to produce a dried inorganic material having a moisture content of
less than about 20% by weight; outletting the exhaust gases and the
dried inorganic material from the dryer vessel through a dryer
outlet; conveying the exhaust gases and the dried inorganic
material together through a dryer outlet conduit that extends from
the dryer outlet to a solids/gas separator; drawing the exhaust
gases from the solids/gas separator using an air moving device in
fluid communication with the solids/gas separator, wherein the air
moving device also reduces backpressure in the dryer vessel by
drawing the exhaust gases from the dryer vessel through the dryer
outlet conduit to the solids/gas separator.
6. A method according to claim 5 wherein the exhaust gas contacting
the waste material feedstock is at an initial temperature between
about 1,100.degree. F. and about 1,600.degree. F.
7. A method according to claim 5 wherein the waste material
feedstock comprises at least about 50% by weight moisture.
8. A method according to claim 5 further comprising the steps of
granulating, pelletizing or prilling the dried material to produce
a soil builder product suitable for conventional handling,
transport or use.
9. A method for producing a dried product from an inorganic waste
material feedstock comprising: operating a gas turbine generator to
produce electricity and exhaust gases; contacting the exhaust gases
with the waste material feedstock in a dryer vessel for a contact
time sufficient to produce a dried inorganic material having a
moisture content less than about 20% by weight; outletting the
exhaust gases and the dried inorganic material from the dryer
vessel through a dryer outlet; conveying the exhaust gases and the
dried inorganic material together through a dryer outlet conduit
that extends from the dryer outlet to a solids/gas separator;
drawing the exhaust gases from the solids/gas separator using an
air moving device in fluid communication with the solids/gas
separator, wherein the air moving device also reduces backpressure
in the dryer vessel by drawing the exhaust gases from the dryer
vessel through the dryer outlet conduit to the solids/gas
separator; and processing and forming the dried inorganic material
into a granular, pellet or prill form of product suitable for
conventional handling, transport or use.
10. A method according to claim 9 wherein the waste material
feedstock comprises a moisture content of at least about 50% by
weight.
11. A method according to claim 10 wherein the moisture content is
at least about 70% by weight.
12. A method according to claim 9 wherein the dried inorganic
material comprises a moisture content less than about 15% by
weight.
13. A method according to claim 9 wherein the product comprises a
moisture content less than about 10% by weight.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
11/399,765, filed Apr. 7, 2006, which is a divisional of
application Ser. No. 10/895,030, filed Jul. 19, 2004, now U.S. Pat.
No. 7,024,800, which applications are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to processes, systems and equipment
for economically converting waste, intermediate or raw materials,
either organic or inorganic in nature, into products useful as
animal or human food, fuel products, recyclable materials for
further or new processing, fertilizer or soil builder products,
materials for disposal at reduced volumes and final products for
market.
BACKGROUND OF THE INVENTION
[0003] Industrial processing facilities for food, paper, drug and
other manufacturing, processing and packaging are becoming larger
and more concentrated. Consequently, the waste streams produced by
these facilities are becoming increasingly larger, more
concentrated locally and more difficult and costly to dispose of
due to government regulations as well as decreasing numbers and
sizes of landfill sites that are available for waste disposal. More
people are consuming commercially prepared and processed food both
in and out of the home than ever before. This is true not only in
the United States, but in other countries as well. This phenomenon
creates an enormous amount of waste, i.e., food scraps, over-ripe
food, trimmings, spoilage and animal parts discarded during food
preparation, that is concentrated in large processing facilities
and that must be disposed of in municipal sewage, landfills or
incinerators. The waste is produced in larger and larger amounts in
facilities that produce pre-prepared food products, such as frozen
foods, pre-prepared, ready-to-eat salad mixes, heat-and-serve
meals, and the like for home, institutional, airline, hotel and
other uses. This waste is frequently difficult and costly to
dispose of, primarily because it commonly has high water content
and has little economic value as a fuel. The art is replete with
various complex processes and systems that address the problems of
such waste disposal and/or conversion to useful, recyclable or
disposable products. However, most prior processes and systems are
not practical or desirable due to economic considerations, due to
the limited type of waste that can be treated or processed in a
particular system, due to environmental problems caused by
operation of the processes or system or due to other disadvantages.
Moreover, the eruption of transmittable spongiform encephalopathy
(TSE), particularly bovine spongiform encephalopathy (BSE) and
scrapie diseases, has made inactivation of pathogenic agents
essential, whether the waste material is processed for recycle or
for disposal. Animal wastes, such as offal, paunch waste material
and carcasses, are subject to carrying infectious agents including
fungi, bacteria, viruses and prions associated with BSE, TSE, etc.
The prior art processes available are either not satisfactorily
effective from a technical standpoint or are not economically
desirable. A need therefore exists for methods of processing and/or
disposal of food processing, slaughter house, and similar wastes
without the technical or economic disadvantages of the prior
art.
[0004] Examples of the prior art publications that have addressed
the above problems by digestion, incineration, volume reduction
and/or decomposition include U.S. Pat. Nos. 5,685,153 to Dickinson
et al.; 6,197,081 to Schmidt; 6,506,311 to DeGarmo et al.;
6,534,105 to Kartchner; 6,638,757 to Teran et al.; 6,716,360 to
Titmas; U.S. Patent Applications 2002/0122850 by Kartchner,
2003/0098227 by Okamoto et al. and 2004/0055716 by Landalv et al.,
the disclosures of which are incorporated herein by reference in
their entirety.
[0005] Another problem existing in waste treatment and disposal
operations is air pollution, including greenhouse gas emissions,
including methane and CO.sub.2, and emission of gases having
noxious odors, such as slaughterhouse and rendering plant
operations. As residential housing areas have expanded, many have
encroached on land adjacent to various food processing and other
industrial operations, and complaints from residents regarding the
noxious odors escalate. The prior art has offered little to
satisfactorily and economically address the problems of controlling
and preventing noxious odors from industrial manufacturing
facilities and waste disposal facilities.
[0006] There is also a general problem of removal of water from
high water content, dilute process streams, whether it is a waste
stream, final product stream or an intermediate process stream. The
removal of water from process streams having a high water content
is costly, energy intensive and time consuming.
[0007] It is apparent from the above that there is a substantial
unmet need for environmentally and economically acceptable
technologies for disposal of various waste materials, for control
of noxious and greenhouse gases, for conversion of wastes into
useful or recyclable products and for efficient and economical
removal of water from high water content process streams. The
present invention is directed to methods, apparatus, systems and
products for meeting some or all of these needs.
SUMMARY OF THE INVENTION
[0008] The present invention provides economical and simplified
methods, systems and apparatus for converting organic and inorganic
waste materials into products that are useful as animal feed,
fuels, recyclable materials for processing and other uses. The
present invention further provides economical and simplified
methods, systems and apparatus for controlling and containing
noxious, odoriferous and greenhouse gases from various industrial
and waste treatment operations.
[0009] In one aspect, this invention provides a method for
processing a waste material feedstock comprising operating a gas
turbine generator to produce electricity and exhaust gases;
contacting the exhaust gases with the waste material 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 waste material feedstock, a dried
material having a moisture content less than about 20% by weight;
and optionally provides for processing and forming the dried
material into a granular, pellet or prill product form suitable for
conventional handling and transport.
[0010] In another aspect, this invention provides a method for
processing a waste material 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 waste
material feedstock having a moisture content of at least about 30%
by weight in a dryer vessel for a contact time sufficient to
produce a dried material having a moisture content of less than
about 20% by weight, and optionally provides for granulating,
pelletizing or prilling the dried material into a product form
suitable for conventional handling and transport. Optionally, the
contact of the exhaust gases and the waste material feedstock is
conducted without significant oxidation of the waste material
feedstock.
[0011] In another aspect, this invention provides apparatus for
drying and/or converting waste material feedstock comprising a gas
turbine in combination with a dryer vessel adapted for receiving
waste material 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 waste material feedstock by direct
contact of the exhaust gases and the waste material feedstock.
[0012] In another aspect, this invention provides a portable system
for processing waste material feedstock comprising at least one
portable dryer unit adapted for drying or heat treating a waste
material feedstock to produce a dried or altered material and at
least one portable processing unit adapted for converting the dried
or altered material from the dryer unit into a product having a
form suitable for conventional handling and transport, 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.
[0013] 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 as well as protection
from weather conditions.
[0014] In another aspect, this invention provides a product
comprising a waste material feedstock thermally treated at
sufficient temperatures and without significant oxidation for a
sufficient period of time to destroy or convert to acceptable forms
substantially all undesired components present in the waste
material feedstock, which comprise undesired organisms,
microorganisms, pesticides, antibiotics, hormones, prions or
viruses. Preferably the product contains less than detectable
levels of each such undesired component not so destroyed or
converted, and optionally further provides such thermally treated
material in the form of a product suitable for conventional
handling and transport. This invention further provides a product
comprising thermally treated waste material 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 waste material
feedstock with gas turbine exhaust gases in a confined space in the
absence of significant oxidation of the waste material
feedstock.
[0015] In another aspect, this invention provides a dried or
altered material or product comprising a waste material feedstock
thermally treated at sufficient temperatures without significant
oxidation and for sufficient period of time to provide a
self-binding product suitable for conventional handling and
transport.
[0016] In another aspect, this invention provides a system for
processing greenhouse gases and noxious or odoriferous gases from
waste material feedstock and/or such gases emitted by the facility
producing a waste material feedstock comprising a gas turbine
having a combustion air intake and a facility having ventilation
air exhausted from the facility, 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
facility. 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 heat
treating waste material feedstock. In an alternative aspect, this
invention provides said systems for processing manufacturing 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.
[0017] In another aspect, this invention provides apparatus for
treating waste material feedstock comprising a gas turbine having a
combustion air intake adapted to receive ventilation air from a
facility producing waste material feedstock, a dryer vessel having
a connection adapted for receiving exhaust gases from the gas
turbine and having an inlet for receiving waste material feedstock.
Optionally the combustion air intake can be adapted for connection
to the facility ventilation system whereby the combustion air
intake receives substantially all the ventilation air exhausted
from the facility. 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.
[0018] The above aspects and other aspects will be apparent to one
skilled in the art from the disclosure herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic diagram of a process for treating
waste material feedstock using the process and equipment in
accordance with the present invention.
[0020] FIG. 2 is a plan view of the process units according to this
invention in the form of portable skid-mounted, truckable
units.
[0021] 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.
[0022] 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.
[0023] FIG. 5 is a schematic of processes for preventing emission
of greenhouse, noxious odors and other gases to the atmosphere
using the systems of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] This invention provides an economical, efficient and
simplified solution to the increasingly severe problem of
environmental pollution caused by waste material and gases from
industrial operations. Prior art methods and systems provided to
date either are not sufficiently effective in conversion of such
waste material 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, including 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).
[0025] 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. Digestion or composting systems
designed to produce biogas, typically methane, for fuel do not
provide economically beneficial production of fuel 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, is a "dirty" fuel in that it produces environmentally
unacceptable emissions when burned and/or 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, due to corrosion or
uncontrollable, unpredictable burning conditions. Digestion and
compo sting systems designed to produce a usable sludge have the
drawback that such sludge products produced are not usually free of
biologic or chemical contaminants that are undesirable or
prohibited for use or disposal, such as on crop land. Consequently,
biogas production operations produce a depleted sludge that is
costly to dispose of in an environmentally acceptable way, which is
frequently in a landfill operation qualified to take such
sludge.
[0026] 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 by products 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 and pyrolysis systems
produce a product that may be sufficiently sterilized, the product
may contain other undesirable byproducts of the incineration and
pyrolysis such as carcinogens, making the product unsuitable for
animal feed, recycle or other desired uses, thus requiring
undesirable disposal in landfill. And, incineration or partial
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.
[0027] Prior art systems have not satisfactorily addressed the
problem of noxious gases and greenhouse gases that are produced in
industrial manufacturing operations and in waste material treatment
operations. Sources of such gases are the manufacturing processes
themselves, the waste material produced and the bioconversion or
decomposition of the waste material. These gases are typically
vented or released to the atmosphere, but may be 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.
[0028] The present invention provides new technology in the form of
processes, apparatus and systems for conversion of waste material
feedstocks to useful, environmentally acceptable materials and
products. In addition, the present invention provides technology
which reduces or eliminates the undesirable environmental impacts
of noxious and greenhouse gases produced in manufacturing
operations and in bioconversion of waste materials from the
manufacturing operations. One major advantage of the present
invention resides in the aspect that, in most waste material
feedstock processing according to this invention, all waste solids
can be optionally contained within the processes and systems and
become part of the final product produced by the processes and
systems of this invention. Thus, the present invention can
completely eliminate the necessity of disposing of any remaining
sludge or other solids in a landfill by converting and/or
incorporating all the waste material feedstock solids into the
final product.
[0029] The term "waste material feedstock" is used herein to mean
and include waste matter which comprises organic matter and which
comprises inorganic matter, or mixtures thereof. Included in the
organic waste matter category are: woody or cellulosic and chemical
waste products from agricultural operations, such as bagasse, rice
hulls, straw, alfalfa, orchard and vineyard prunings, citrus pulp,
corn cobs, beet pulp, hatchery waste, yard wastes, landscaping
wastes, mushroom growing wastes, etc., from forestry and lumber
operations, such as scrap wood, sawdust, bark, limbs, etc., from
pulp and paper operations, including Kraft mill black liquor from
sulfate pulping, from de-inking mill operations, from nursery
operations, such as dead or diseased plants and from building
demolition and construction; mixed plastics or automobile shredder
residue (ASR); food processing wastes from processed or
pre-processed food product manufacturing, such as such as frozen
foods, pre-prepared, ready-to-eat salad mixes, heat-and-serve
meals, canned foods, and food services businesses, such as
restaurants, institutional meal providers, airline meal providers,
etc.; residual meat, bones, offal, skin, poultry waste, feathers,
feather meal, hair, hair meal, seafood meal, blood, blood meal,
bone meal etc. from slaughter house and meat and fish packing
operations; livestock, poultry and pet carcasses from farms,
feedlots, slaughter houses, and veterinarian clinics, including
cattle, sheep, goats, hogs, horses, chickens, geese, ducks, and
virtually any other animal from any source of carcasses, body
parts, organs or tissues that must be disposed of; body parts,
organs and tissues from medical facilities; fermentation and
distillation operation wastes, such as soy sauce waste, wine and
sake lees, tofu refuse, grape skins and seeds, mash and sour mash
residue, etc.; cheese making operations, recycle waste operations,
such as paper, plastics, tires, foamed styrene, cardboard, etc. and
other servicing, processing and manufacturing operations that
involve organic materials. Included in the inorganic matter
category are: product streams, waste streams and materials from
mining operations, iron and steel mill operations, foundry
operations, well drilling operations, production of zinc borate,
zinc oxide, magnesium oxide, silicon dioxide, titanium dioxide,
alumina trihydrate, ceramic fibers, iron oxide, gypsum, gypsum
board, silica, lime, calcium carbonate and the like. Another
feedstock useful in this invention is contaminated soil for
remediation processing, e.g., soil contaminated with hydrocarbon
fuels, pesticides, nitrates and the like. As will be apparent to
one skilled in the art, mixtures of organic and inorganic waste
materials will be useful in this invention. The preferred waste
material feedstock for use in this invention is that with a high
water content, which makes that feedstock uneconomical or
undesirable to treat or process by prior art methods. Large
components of a waste material feedstock, such as prunings,
building demolition materials, fruit pits, tires, bones, carcasses,
etc., preferably are comminuted or shredded to particle sizes
suitable for processing in the systems and equipment selected for
carrying out this invention. The sizing may be done using any
suitable equipment, such as mills, choppers or shredders. Sizing
should be done in an enclosed environment to avoid aerosol pathogen
emissions into the outside environment. Typically, the waste
material will have a high water content, as discussed below. The
term "waste material feedstock" is also used herein to include
intermediate products and raw materials for further processing into
other products which are not waste products. For example, this
invention can provide efficient processes and systems for removal
of water from process streams and/or provide heating to thermally
convert or react a product stream to a converted or reacted product
(in batch or continuous operations). Other examples of the various
uses of this invention include drying and treating slaughterhouse
waste to produce a slurried or solid (e.g., granulated) animal feed
having significant protein and/or calcium content; processing
lumber and paper manufacturing wastes or intermediate streams to
produce recyclable cellulose, paper or wood materials or products
useful in manufacture of particle board, cardboard, etc., or to
produce a solid cellulose or wood product useful as a fuel; drying
and processing potato peelings and other waste from potato
processing facilities to produce an animal feed supplement or a
fertilizer/soil builder product; removing water from and/or
converting (cooking, pasteurizing, sterilizing, etc.) process
streams in human food production facilities, such as production of
oatmeal, corn flakes, corn syrup, corn meal, mashed potatoes,
sugar, milk, cheese, snack foods and other food products such as
pet food; and removing water from and/or converting or reacting
process streams in drug, chemical and other manufacturing
facilities. As is apparent, the systems and processes of this
invention can be used to process a feedstock by dehydration without
conversion or reaction, by conversion or reaction without
dehydration, or by any combination or proportion of both. The
systems and apparatus of this invention can also be adapted for
installation at particular individual facilities to intercept the
waste streams therefrom and prevent such waste streams from
entering and burdening municipal sewage treatment facilities. For
example, large food processing facilities for producing prepared
meals for institutions, airlines, etc., normally dump their waste
food materials in a municipal sewer or landfill. Waste processing
systems and units according to this invention can be sized and
installed at such a facility to process such waste food materials
to produce a useful product, such as an animal feed or a
fertilizer/soil builder product which has economic value, and to
reduce the burden on the 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, organic hazardous waste, etc., from office buildings,
hospitals, hotels, etc., to produce, on site, a fertilizer,
recyclable or safe disposal product, thus further relieving the
burden on the municipal sewage system. This aspect of this
invention being designed for processing animal waste material and
municipal sewage, is disclosed in commonly assigned copending U.S.
patent application Ser. No. 10/894,645 filed on Jul. 19, 2004, the
disclosure of which is incorporated herein by reference in its
entirety.
[0030] The present invention provides a simplified, economically
efficient alternative to the prior art which provides in its
preferred aspects, a 100% usable product which provides 100%
conversion of waste material feedstock solids into useful products
and which eliminates the problem unsolved by the prior art of
disposal of solids left over from various waste material feedstock
treatments. The present invention is principally useful, depending
on the waste material feedstock to be processed, in processing
waste materials into food products, animal feed products, fuel
products, fertilizer or soil builder/soil supplement products,
products suitable for efficient recycle, remanufacture, reuse or
transport, and safe products suitable for environmentally
acceptable disposal. According to the present invention, the animal
or plant nutrient values in the product from a waste material
feedstock can be maximized if compo sting, digestion, incineration
and oxidation of the waste material feedstock are avoided or at
least minimized. In this invention, the high temperature treatment
of waste material 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 waste
material 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 waste material 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 waste material 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 used in
conventional product handling and transport equipment and
operations. Additionally, the present invention processes and
systems can be adapted to produce liquid or slurry products that
comprise waste material feedstocks (including intermediate process
streams or intermediate products) that have been dehydrated to the
desired moisture content level and/or have been converted, reacted
or altered physically and/or chemically as desired. This invention
also provides for recovering and recycling the water removed from
the waste material feedstock, which water can be used for process
water, 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 or resulting from this invention other than the desired
products suitable for commercial use. The selection and adaptation
of the processes, apparatus and systems of this invention to treat
or process a particular feedstock to produce a particular desired
solid, liquid or slurry product for end use, recycle or disposal
will be apparent to one skilled in the art from the disclosure
herein.
[0031] According to this invention, a most efficient way of
providing the hot gases for contact with the waste material
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 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 the electricity 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 waste material feedstock to produce the desired quality and
quantity of products without concern for or being constrained by
any particular minimum or necessary level of electricity output or
the need for an unchanging level of electricity output.
[0032] One important feature of the process and apparatus of this
invention is that the gas turbine and the waste material 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. If desired, combustion can be at stoichiometric
ratio for peak EGT operation at maximum temperature and maximum
heat input for the process and system of this invention. 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 temperatures set forth herein prevents
significant oxidation of the waste material feedstock in the dryer
vessel, preserves the maximum nutrient value in the waste material
feedstock for containment in the end product and, when the output
of the dryer vessel is a dry, oxidizable material, 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. In other preferred operations of this
invention it may be desired or essential that air or oxygen be
introduced in controlled quantities or ratios to provide a desired
oxidation or chemical conversion of the waste material feedstock in
the dryer vessel.
[0033] In the operation of the processes and apparatus of this
invention, it is preferred that when the waste material feedstock
is an organic material, it should be as fresh as possible with a
high moisture content. In other words, such a waste material
feedstock should have undergone no, or as little as practical,
compo sting, decay, digestion or other bioconversion prior to
processing according to this invention. This provides the highest
nutrient value and organic matter content in the final product and
is desired where the product produced is a food product, an animal
feed product, a fertilizer or soil builder product or other product
where nutrient value or organic matter content is important. 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 various
operations and manufacturing facilities and enables processing of
the waste material feedstock from such operations and facilities
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 waste material feedstock to a distant location
for processing or disposal. Eliminating the necessity of
transporting waste material 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 waste material feedstock processing where the truck mounted
units are easily moved from one waste material feedstock production
or accumulation site to another, in order to maximize the
utilization of the capital investment in the equipment systems
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 operation or manufacturing locations in a
particular area where a permanent installation at any single
location is not needed or is not economically justifiable. The
system of this invention can also be scaled to appropriate size for
an individual operation or manufacturing location to operate full
time to continually process the waste material feedstock
continually produced in that location, so that waste material
feedstock stockpile or excess waste material feedstock at any time
the manufacturing facility is in operation is minimized.
[0034] For use in this invention, it is preferred that the waste
material 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 waste material feedstock
is moved by augers, front end loaders, back hoes, conveyor belts
and the like, particularly in slaughterhouse, farm, forestry,
landscape and similar operations. However, in those and other
operations the waste material feedstock may be prepared in the form
of a pump able slurry, where the water content of the waste
material feedstock may be as high as 90%, 95% or even 98%. In
addition, the waste material feedstock may be a solution with all
solids dissolved therein, where the solids are precipitated out as
the water is evaporated from the feedstock in the processes and
systems of this invention. The present invention can efficiently
and economically process such high water content waste material
feedstocks to not only recover the solids content in the form of a
final product, but to also recover the process water, which can be
recycled for industrial or process use, for livestock drinking
water, for crop or landscape irrigation, etc. This invention can
handle high water content waste material 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 for preheating waste material feedstock,
process heat, etc. Instead of holding high water content waste
material feedstocks in open ponds, as is conventionally done in
many industrial and manufacturing operations, this invention
enables holding the waste material in enclosures or tanks for
essentially immediate processing, which eliminates the air
pollution, odor and environmental problems associated with open
ponds. This invention can be adapted as disclosed herein, to
contain and process not only the water and solids but also the
gases produced in a manufacturing operation. In some cases it may
be desirable for economic operation reasons to mechanically
separate part of the water from high-water content waste materials,
e.g., by centrifuges, filters or presses, before processing the
waste material in the system of this invention. Such separated
water can be recycled for use as disclosed above.
[0035] It is recognized that a raw waste material feedstock will
typically contain other material such as straw, twine, wire,
gravel, rocks, jute or plastic bags, etc. Such materials are
processible as part of the waste material 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
waste material 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 product without
significant interference with the normal operation of the processes
and apparatus of this invention or with the end use of the 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 waste
material feedstock or during processing according to this
invention. The waste material 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 waste material feedstock preparation can include a
washing step, which may be useful in very dry waste material, to
remove excess salt content or other components that may not be
desired in a final product.
[0036] 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.
[0037] 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.
[0038] Examples of commercially available gas turbines and gas
turbine generators useful in the present invention include the
following (rated megawatt (MW) outputs are approximate): [0039]
Rolls Royce Gas Turbine Engines Allison 501-KB5, -KB5S or -KB7
having a standard condition rated output of 3.9 MW [0040] European
Gas Turbines Tornado having rated output of 7.0 MW [0041] Solar
Mars 90 having rated output of 9.4 MW and Solar Mars 100 having
rated output of 10.7 MW [0042] Solar Taros 60 having rated output
of 5.5 MW and Solar Taros 70 having rated output of 7.5 MW 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.
[0043] The dryer vessel employed in this invention can be any type
or configuration that is suitable for drying the waste material
feedstock available and that can be adapted for receiving the gas
turbine exhaust gases and receiving the waste material feedstock
without allowing a significant amount of outside air to enter the
drying chamber in the dryer vessel where the exhaust gases contact
the waste material 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 waste material feedstock. As previously pointed out, this is
preferred to preserve the organic matter, carbonaceous and/or
nutrient values present in those types of waste material
feedstocks, 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 offline.
[0044] It will be recognized that in some operations of this
invention, not all outside air can be excluded and oxidation of the
waste material feedstock cannot be completely precluded, primarily
because of the air present in and entrained in the waste material
feedstock, the air dissolved in the moisture present in the waste
material 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 waste material 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 waste material 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 waste material
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
waste material 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
waste material feedstock and the desired conversion and destruction
of various waste material 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
for some applications of this invention, 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 waste material feedstock to achieve these desired
results and to maximize the nutrient value in the final products.
In other applications of this invention the temperatures, contact
times and other operating parameters of this invention can be
adapted to achieve a desired level or degree of oxidation or
pyrolysis, if the properties of the final product to be made using
the systems of this invention require oxidation or pyrolysis of the
feedstock.
[0045] Dry or low moisture content waste material feedstock is
likely to have more air entrained in the interstices among the
particles than wet or high moisture content waste material
feedstock, and elimination of such entrained air from a dry waste
material feedstock before introduction into the dryer vessel may
not normally be economically practical. However, consistent with
other operational aspects of this invention, it is often preferable
to use high moisture, low air content waste material feedstock, and
may be preferable to add water to a dry waste material feedstock to
displace air there from 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 waste material, 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.
[0046] Exclusion of outside air is also preferred for economic
efficiency as well, because heating excess or outside air along
with heating the waste material feedstock reduces the efficiency of
the process. In some instances where the waste material 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 waste material 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 waste material feedstocks, water may be considered
a process aid added before entry into the dryer vessel.
[0047] It will be recognized that the operation of the dryer vessel
is normally to dry or reduce the moisture content of the waste
material feedstock, but it is to also achieve the high temperature
heating of the waste material feedstock to convert or destroy
undesired components and to achieve a chemical or thermal
alteration in the feedstock to provide properties desired in the
final product. As noted, one aspect of this invention is the
thermal conversion of the various components of the waste material
feedstock without significant oxidation from the outside air. Since
the specific components of waste material feedstocks are numerous
and varied, it is not clearly understood what specific chemical
reactions may be taking place in the various 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.
[0048] 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 various components in the
waste material feedstock. For example, the product produced can be
an essentially self-binding solid product that can 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 solid
products 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 product handling, transport and application
equipment. Waste material feedstocks that range from very high to
very low proportion of organic matter 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 solid products of this invention, if desired.
Third is the recognition that in some operations of processing a
very low moisture content waste material 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 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 or other components present in the
feedstock.
[0049] The types of dryer vessels that can be used in this
invention are, for example, the following: [0050] Rotary drum with
or without internal scrapers, agitation plates and/or paddles
[0051] Stationary "porcupine" drum dryer with or without scrapers
and/or agitator plates and/or paddles [0052] Triple pass stepped
drying cylinder or rotary drum dryer systems with or without
scrapers and/or agitator plates and/or paddles [0053] Rotary drum
dryer systems with or without steam tubes and with or without
scrapers and/or agitator plates and/or paddles [0054] Turbo-dryer
or turbulizer systems [0055] Conveyor dryer systems with or without
scrapers and/or agitator plates and/or paddles [0056] Indirect or
direct contact dryer systems with or without scrapers and/or
agitator plates and/or paddles [0057] Tray dryers [0058] Fluid bed
dryers [0059] Evaporator systems [0060] Baking ovens
[0061] Examples of commercially available dryer vessels useful in
or that can be adapted for use in this invention include: [0062]
Scott AST Dryer.TM. Systems [0063] Simon Dryer Ltd.--Drum dryers
[0064] Wyssmont Turbo Dryer systems [0065] Duske Engineering Co.,
Inc. [0066] Energy Unlimited drying systems [0067] The Onix
Corporation dehydration systems [0068] International Technology
Systems, Inc. direct or indirect dryer systems [0069] Pulse Drying
Systems, Inc. [0070] MEC Company dryer systems Further examples of
dryer vessels useful in or that can be adapted for use in this
invention are disclosed in U.S. Pat. Nos. 5,746,006 to Duske et al.
and 5,570,517 and 6,367,163 to Luker, the disclosures of which are
incorporated herein by reference in their entirety.
[0071] As noted above the "dryer vessel" does not necessarily
always function primarily as a dryer by removing moisture from the
waste material feedstock in the system of this invention. The dryer
vessel also functions as the thermal
treatment/conversion/alteration vessel or oven in which the waste
material 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 waste material feedstock, but can provide
indirect heating of the waste material feedstock to achieve the
drying and/or thermal treatment/conversion/alteration desired
according to this invention. The dryer vessel can be lined with
appropriate material to prevent or reduce corrosion, erosion or
excessive wear. It will be recognized that the systems of this
invention can be adapted to perform various functions in various
configurations in a particular installation or operation. For
example, two dryer vessels can be operated in series where a high
water content feedstock is dried in the first dryer vessel then the
output from the first dryer vessel is thermally treated in the
second dryer vessel to achieve the desired chemical or physical
conversion or alteration. In such an arrangement, the exhaust gases
can be supplied from a single gas turbine exhaust split between the
two dryer vessels, or can be supplied by two separate gas turbines.
From this example it can be seen that the processes, apparatus and
systems of this invention can be adapted to operate various
equipment components in series or in parallel to perform various
processing functions desired following the teachings of this
invention to achieve the effective and economic operation
thereof.
[0072] Another aspect of the dryer vessel adapted for use in this
invention is that the dryer vessel preferably also functions as the
silencer 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 preferably 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 waste
material 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 gas
venting. The turbine exhaust can optionally 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.
[0073] 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 waste
material 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.
[0074] Another advantage provided by this invention results from
the contact of the gas turbine exhaust gas with the waste material
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 waste material feedstock, where they
remain absorbed, complexed or fixed in the dried or treated
material exiting the dryer vessel and in the product after
processing into granular, pellet or prill or other form. This
provides the advantage of both lowering or eliminating the
emissions of NO.sub.x and SO.sub.x (and CO/CO.sub.2) into the
atmosphere and adding the nitrogen, sulfur and carbon components to
the nutrient value of the product produced by the process and
apparatus of this invention.
[0075] 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 waste material 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
waste material 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 waste material feedstock is contacted with high
temperature gases. Such contact causes the formation, sometimes
instantly, of superheated steam as the moisture comes out of the
waste material feedstock, then that superheated steam heats and
drives the moisture out of adjacent waste material feedstock. It is
believed that this mechanism is responsible for quick drying of the
waste material feedstock to a low moisture content so that the
remaining residence time of the waste material feedstock in the
dryer vessel contributes to the desired thermal
treatment/conversion/alteration or "cooking" thereof according to
this invention. Some waste material feedstocks may require lower
temperatures but longer residence time to achieve the conversion or
"cooking" needed to produce a product having self-binding or other
desired properties. The temperature of the 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 material should be at least about 175.degree. F.
and preferably at least about 200.degree. F.
[0076] The self-binding properties of the materials and products of
this invention are one of the important preferred aspects 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
frequently preferred that the operating conditions should be those
that cook and convert the waste material feedstock to produce a
self-binding product, such as an animal feed product, recyclable
product, fuel product, etc. Those operating conditions will depend
on the moisture content and the organic matter content of the waste
material 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 or other 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 waste material feedstock
and exhaust gases, temperatures achieved by the feedstock solids,
the residence time of the waste material feedstock solids in the
dryer vessel at elevated temperatures and other process factors.
These conditions will determine the temperature to which the solids
will need to be raised and the length of time the solids are
subjected to the elevated temperatures in order to produce a
self-binding product. 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 waste material feedstock following the disclosure
herein.
[0077] As used herein the term "converted material" is used to
refer to and means the dried waste material feedstock which is
produced in the dryer vessel by reducing the moisture content of
the waste material 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 "converted
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 converted
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 product
suitable for conventional handling, packaging and/or transport. The
converted material can also be milled or otherwise powdered and
made into a slurry or other liquid or pumpable product that can be
recycled or used as intended. Local economics will have an impact
on determining the end use to be made of the material produced from
the dryer vessel or the final product produced from the system of
this invention and whether the material from the dryer vessel is
subjected to further processing as discussed below.
[0078] 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.
[0079] An extrusion pelletizer is one of the preferred process
units for use in connection with or as part of 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 provide
or further 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 material from the dryer
vessel is milled, and 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 heating and temperatures achieved 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 waste material 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
waste material 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.
[0080] The waste material 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 waste material feedstock of lower moisture content, for
example, as low as about 40% by weight or even 30% by weight can be
processed in this invention. The preferred waste material 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 waste material 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 waste material 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 waste
material feedstock, which enhances the efficiency of the process.
It is preferred for operation of the process and apparatus of this
invention that the waste material feedstock be mixed and blended
among batches or different parts (top, bottom, indoor, outdoor,
etc.) of the same batches to provide a uniformity of waste material
feedstock properties. This preferred preparation enables the
production of a more uniform material from the dryer vessel, and
simplifies control of the process operations. The temperature of
the waste material 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.
The waste material feedstock may be used at any temperature direct
from a manufacturing facility or from a process unit, which may be
at an elevated temperature. The economics of the systems of this
invention are usually improved if the waste material feedstock is
at an elevated temperature or is preheated 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, and may be done with heat
recovered and recycled from the process systems of this
invention.
[0081] The contact time between the turbine exhaust gases and the
waste material 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 waste material
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, the
desired level of self-binding or other desired properties 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 waste material feedstock is a slaughterhouse waste
material comminuted to small particle size and having a moisture
content of about 70% by weight and a temperature of about
65.degree. F. and 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 waste material 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 waste material 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.
[0082] 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.
[0083] The solids output from the dryer vessel, referred to herein
as converted material, are typically further processed by milling,
granulating, pelletizing, prilling or other processing to produce a
final feed, fuel, recycle or other product in the form desired for
packaging or bulk distribution, transport and use. 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.
Whatever the product in whatever form, the process, system and
equipment of this invention provide for environmentally and
economically effective processing of waste material feedstocks to
remove them as environmental liabilities and provide products which
are commercially useful, and to eliminate disposal in a municipal
sewer or landfill. This invention can be used to produce a variety
of products and materials from waste material 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
feed, fuel, recyclable or other 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.
[0084] 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 waste material 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 final 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 product for
specialized use.
[0085] 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 manufacturing operations, from various processing
facilities, and from compo sting or organic waste material,
referred to herein as "emissions gases." Manufacturing operations
are coming under increasing regulation by federal and state
agencies due to increasing pressure from population areas near the
manufacturing operations. The regulation is directed to two aspects
of air quality. The first is noxious odors in emissions gases,
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 (commonly
released from composting waste material stockpiles or lagoons) 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.) While CH.sub.4 is the main
greenhouse gas produced by bioconversion of organic waste material,
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 to have a CO.sub.2 equivalent of about 310. This
invention can be used, as disclosed herein, to essentially
eliminate atmospheric release of emission gases by containing and
processing the emission gases, by immediate processing of waste
material feedstock to prevent decomposition or bioconversion of
organic matter and/or containing and processing emissions from
decomposition or bioconversion that takes place before the waste
material feedstock can be processed.
[0086] The systems of this invention are particularly useful in
essentially eliminating the release of emission gases from
manufacturing operations. In the basic system of this invention,
the gas turbine exhaust is connected to the dryer vessel. To
control emission gases produced in a manufacturing operation, the
gas turbine air intake is connected to the manufacturing facility
ventilation system so that the ventilation air exhausted from the
facility is directed into the gas turbine air intake where two
processes normally will take place. First, the emission gases are
burned along with the regular gas turbine 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 waste material feedstock, where
the NO.sub.x and SO.sub.x and to some extent CO.sub.x gases are
absorbed into or complexed with the waste material feedstock as it
is dried and/or thermally treated to form a converted material, and
preferably to form a final product. This aspect of this invention
prevents the emission gases from entering the atmosphere.
[0087] Existing manufacturing facilities that can immediately
directly and efficiently utilize this invention for control of
emission 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 exhaust air from such facilities is directed to
the gas turbine combustion air inlet. In addition, facilities can
be economically enclosed (e.g. by canvas walls) and ventilated by
forced air (with or without climate control) to collect essentially
all the emission gases from the manufacturing operation and
directing the exhaust vent air to the gas turbine air intake.
[0088] 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 manufacturing facility is fed to
the gas turbine air intake to prevent release of emission 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 facility 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 product produced by the systems of this invention.
Although the methane or other oxidizable gases in the emission
gases will not normally constitute a significant portion of the
fuel requirements of the system of this invention, it is burned to
produce heat and is not released to the atmosphere. Nevertheless,
every kg of emission gas burned reduces the outside gas turbine
fuel requirement by an equivalent 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 manufacturing facility substantially contains and muffles
the high frequency turbine inlet noise.
[0089] 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 emission gases 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 manufacturing facility exhaust
vent air can be directed to the combustion air intake so the
emission gases are burned and preferably so the combustion gases
are contacted with the waste material feedstock.
[0090] 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 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 waste material 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.
[0091] The waste material feedstock is typically introduced into
the system by mechanical means, such as pump, auger or whatever is
appropriate for a particular feedstock. In this illustration and
example, a front end loader 201, drops a solid waste 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.
[0092] 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 waste material feedstock is 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 waste material 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 waste material 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 waste material feedstock
solids (except for rocks and other foreign objects that are not
processible) into the final products and does not produce a solids
waste stream that must be otherwise disposed of, such as in a
landfill.
[0093] 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 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.
[0094] 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 material or 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.
[0095] 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 slaughterhouse waste material to produce a protein
source animal feed product.
Example of System Sized for Nominal 2.5 Metric Tons/Hr Finished
Product
TABLE-US-00001 [0096] FIG. 1 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 Waste Material 6,500 kg/hr 70% H.sub.2O/
Feedstock 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
Animal 2,500 kg/hr 12% H.sub.2O by wt. Feed Product 15.degree. F.
above Ambient Temp.
[0097] 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
manufacturing operation sites where waste material 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 waste material 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.
[0098] 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.
[0099] 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 waste
material 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.
[0100] FIG. 5 is a schematic process flow chart of some of the
optional systems of this invention. Manufacturing facility
enclosure 900 and waste material pits 901 are enclosed and
ventilated with fresh air 902. The ventilation air 903 from the
facility is fed to the gas turbine 101 as part of the combustion
air feed 904 through air filter 104. The waste material pits 901
can be within the same enclosure or can be separate holding tanks
or lagoons that are enclosed so that all vapors given off by the
waste material can be contained and passed to the gas turbine 101
along with the facility ventilation air 903 for combustion along
with the conventional gas turbine fuel 103, such as locally
available natural gas. This prevents greenhouse and noxious or
acrid gases from the manufacturing operation and the waste material
from being released into the atmosphere, including biogases from
any bioconversion that takes place before the waste material 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 manufacturing operations a way to become acceptable
neighbors with nearby residential areas, because all noxious and
acrid odors from the operation and the waste material can be
contained within the system and incorporated in the final product
or converted to components that are not noxious or acrid before
venting to the atmosphere.
[0101] 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 manufacturing operation or the
processing units in the systems of this invention. Some
manufacturing operations will find that the cost of enclosing an
open manufacturing facility and installing and operating
ventilation in order to contain and process all greenhouse gases
via 903 can be at least partially if not substantially offset by
using the electricity 905 for operation of the ventilation system.
For example, it may be feasible, or necessary in some instances due
to governmental regulation, to cover a normally open manufacturing
operation with inflatable tents, similar to those used for tennis
courts, to provide economical systems for containing and collecting
all emission 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 manufacturing operation,
sold to the power company, used in the systems of this invention or
used in other nearby operations or any combination thereof.
[0102] 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. As disclosed herein, the system is
operated so that the oxidation of the waste material 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. 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.
[0103] Waste material 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
waste material feedstock preferable comes directly from the waste
material pits 901 in facility 900 so it is fresh and has little or
no time for bioconversion. Other waste material feedstock sources
910 can be used or included in the system, such as stockpiled waste
material or waste material from other operations that is brought in
to be combined or mixed with the waste material from the immediate
facility. As disclosed herein, other green waste, organic
materials, inorganic materials or additives can be combined with
the waste material for processing in the system of this
invention.
[0104] 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 the manufacturing facility or preparing
or conditioning the waste material 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, the dry material can be baled, formed into shapes, slurred
for pumping, or can be used alone or in combination with other
materials for incineration to utilize the fuel value of the
material.
[0105] 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 facility ventilation air, e.g., by water
spray, to increase efficiency and power output of the gas turbines,
dewatering very high water content waste material feedstock, etc.
The final pelletized, granulated or prilled product 915 can be
bagged or shipped bulk for conventional handling, transport and end
use.
[0106] 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 operation flexibility for processing
varying feedstock loads and for performing equipment maintenance
without shutting down the operation.
[0107] 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.
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