U.S. patent application number 11/180046 was filed with the patent office on 2006-06-15 for method and installation for conversion into fuel of organic material originating for instance from domestic waste.
Invention is credited to Abraham Jansen.
Application Number | 20060123697 11/180046 |
Document ID | / |
Family ID | 36046788 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060123697 |
Kind Code |
A1 |
Jansen; Abraham |
June 15, 2006 |
Method and installation for conversion into fuel of organic
material originating for instance from domestic waste
Abstract
A method is provided for converting organic material from
domestic refuse into fuel for use in a pulverized coal power plant,
comprising of mixing the organic material with at least one
flammable material while adding binder, and pressing the mixture to
form hard, relatively brittle agglomerates. Further provided is an
installation for converting organic material from domestic refuse
into fuel, comprising a device for mixing the organic material with
at least one flammable material while adding binder, and device for
pressing the mixture to form hard, relatively brittle
agglomerates.
Inventors: |
Jansen; Abraham; (DH Zwolle,
NL) |
Correspondence
Address: |
BOZICEVIC, FIELD & FRANCIS LLP
1900 UNIVERSITY AVENUE
SUITE 200
EAST PALO ALTO
CA
94303
US
|
Family ID: |
36046788 |
Appl. No.: |
11/180046 |
Filed: |
July 11, 2005 |
Current U.S.
Class: |
44/550 ; 44/589;
44/596; 44/605; 44/629; 44/634; 44/636 |
Current CPC
Class: |
C10L 5/361 20130101;
C10L 5/363 20130101; Y02E 50/30 20130101; B30B 11/228 20130101;
C10L 5/44 20130101; Y02E 50/10 20130101; C10L 5/366 20130101; C10L
5/46 20130101 |
Class at
Publication: |
044/550 ;
044/589; 044/596; 044/605; 044/629; 044/634; 044/636 |
International
Class: |
C10L 5/00 20060101
C10L005/00; C10L 5/40 20060101 C10L005/40; C10L 5/06 20060101
C10L005/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 13, 2004 |
NL |
1027726 |
Claims
1. A method for converting organic material into fuel, said method
comprising: mixing the organic material with at least one flammable
material while adding binder to produce a mixture; and pressing the
mixture to form hard, relatively brittle agglomerates; to convert
the organic material into fuel.
2. The method according to claim 1, wherein said organic material
is domestic refuse.
3. The method according to claim 1, wherein the fuel is suitable
for use in a pulverized coal power plant.
4. The method according to claim 1, wherein the organic material is
obtained from domestic waste by at least one of: removing
non-combustible fractions and drying the waste.
5. The method according to claim 1, wherein the organic material is
reduced in size prior to mixing.
6. The method according to claim 1, wherein the flammable material
is a material with a high carbon content.
7. The method according to claim 1, wherein the binder is adapted
to the nature of the materials for mixing.
8. The method according to claim 1, wherein the method comprises
pressing the mixture more than once.
9. The method according to claim 1, wherein said pressing is at an
increased temperature.
10. The method according to claim 1, wherein the mixture is pressed
in a pellet press with flat die.
11. The method according to claim 1, wherein the resulting
agglomerates are ground to powder before being fed to a furnace of
a pulverized coal power plant.
12. The method according to claim 1, wherein the mixture has a
composition and/or calorific value corresponding to that of
coal.
13. An installation for converting organic material into fuel, the
installation comprising: a device for mixing the organic material
with at least one flammable material while adding binder; and a
device for pressing the mixture to form hard, relatively brittle
agglomerates.
14. The installation as claimed in claim 11, wherein said
installation further comprises a device placed before the mixing
device for the purpose of recovering organic material from domestic
waste.
15. The installation according to claim 14, wherein the recovering
device comprises an element for removing non-combustible fractions
and/or an element for drying the waste.
16. The installation as claimed in claim 15, where the installation
further comprises a device for reducing the waste in size placed
between the recovering device and the mixing device.
17. The installation according to claim 13, wherein the mixing
device comprises at least one inlet for organic material, at least
one inlet for a flammable material and at least one inlet for a
binder.
18. The installation according to claim 13, wherein the pressing
device comprises a number of presses placed in series.
19. The installation according to claim 13, wherein the pressing
device is provided with means for feeding at least a part of the
pressed mixture back to its inlet.
20. The installation according to claim 13, wherein the pressing
device is adapted to increase the temperature of the mixture.
21. The installation according to claim 13, wherein the pressing
device comprises at least one pellet press with flat die.
22. The installation according to claim 13, wherein the pressing
device is adapted to generate a pressure and temperature such that
the thereby formed agglomerates can be ground to powder.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Pursuant to 35 U.S.C. .sctn.119, this application claims
priority to the filing date of Dutch Patent Application Serial No.
1027726 filed Dec. 13, 2004; the disclosure of which is herein
incorporated by reference.
INTRODUCTION
[0002] The invention relates to a method for converting organic
material into fuel. The invention relates particularly to a method
with which the organic material can be converted into a type of
fuel which can be ground to powder and is thereby suitable for
burning in a pulverized coal power plant. In this application
"organic material" is understood to include the combustible
fraction of domestic refuse or equivalent industrial waste,
so-called RDF (Refuse Derived Fuel). Fibrous material, such as for
instance wood chippings, also falls however within this
designation.
[0003] It is already known per se to convert domestic refuse into a
fuel which can be used in electricity power plants. Compared to the
combustion of unsorted waste in waste incineration plants (WIPs),
this has the advantage that the combustion efficiency of an average
power plant is considerably higher, while possibly reusable
materials are moreover prevented from being burned together with
the waste. A problem however is that costly additional measures and
provisions are necessary for this purpose, while the thus formed
fuel has a lower net heating value than coal, thereby reducing the
output of the power plant.
[0004] In the non-pre-published Netherlands patent application
1026414 of applicant a method is already described wherein waste is
first comprehensively dried and all kinds of non-combustible or
otherwise disruptive fractions are removed. The non-combustible
fractions contain reusable materials such as metal and glass, which
can thus be recovered. The combustible or RDF fraction is then
mixed with a flammable material and a binder and pressed to form
granules.
[0005] The heretofore known methods, including that of the above
stated patent application, have the drawback that not only the
non-combustible fractions, but also per se combustible materials
such as wood or plastics, have to be separated from the waste
before it can be mixed with flammable material and pressed to form
granules. This is because it must be possible to grind the fuel
granules to powder, like coal, to enable their use in a modern
high-efficiency electricity power plant. If granules obtained with
the methods now known were to be ground, just as coal, in ball
mills, but then without prior separation of plastics and wood, the
plastics and wood would as it were be smeared, and the filters of
the ball mills would become blocked.
[0006] The separation of materials such as wood and plastics does
however require one or more additional steps, whereby the known
methods are relatively time-consuming, complex and expensive.
SUMMARY
[0007] The invention therefore has for its object to improve these
known methods such that it is possible to dispense with the
separation of plastics and/or wood from the waste before this
latter is mixed with flammable material and pressed to form
granules. The invention provides for this purpose a method for
converting organic material, in particular from domestic refuse,
into fuel, particularly for use in a pulverized coal power plant,
comprising of mixing the organic material with at least one
flammable material while adding binder, and pressing the mixture to
form hard, relatively brittle agglomerates.
[0008] By pressing the mixture such that hard and brittle
agglomerates are created, these products of the pressing process
can be admixed directly to coal and pulverized together therewith
and fed to the furnace of a high-efficiency electricity power
plant. Owing to the strong compressing thereof, with pressures
which can be in the order of 30 MPa, the agglomerates have a long
storage life and can, like coal, be stored outside.
[0009] In addition to purely organic material, such as for instance
wood, the method can also be applied, as stated, with organic
material obtained from domestic or industrial waste. The organic
material is then advantageously obtained from domestic waste by
removing non-combustible fractions and/or by drying the waste.
[0010] In order to achieve an optimal mixing of the organic
material with the flammable material, the organic material is
preferably reduced in size prior to mixing.
[0011] A fuel with a high calorific value is obtained when the
flammable material is a material with a high carbon content.
[0012] In order to ensure a good binding between the different
materials and to obtain highly cohesive agglomerates, the binder is
preferably adapted to the nature of the materials for mixing.
[0013] So as to achieve a sufficient measure of compression, it is
recommended that the mixture is pressed more than once.
[0014] It is also advisable for the purpose of obtaining hard and
brittle agglomerates that the mixture be pressed at increased
temperature. It is possible here to envisage temperatures in the
order of 60 to 160 C, preferably 80 to 140 C and more preferably
100 to 120 C.
[0015] An efficient, energy-saving pressing is achieved when the
mixture is pressed in a pellet press with flat die.
[0016] In order to enable high-efficiency combustion of the
resulting agglomerates, the resulting agglomerates are preferably
ground to powder before being fed to a furnace of the pulverized
coal power plant. A ball mill or wheel mill can for instance be
used for this purpose, using which a powder with a maximum particle
size in the order of a few hundred microns can be obtained from the
agglomerates.
[0017] When the mixture has a composition and/or calorific value
corresponding to that of coal, the fuel can be mixed with coal in a
random ratio.
[0018] The invention also has for its object to provide an
installation with which the above described method can be
performed. According to the invention such an installation
comprises a device for mixing the organic material with at least
one flammable material while adding binder, and a device for
pressing the mixture to form hard, relatively brittle
agglomerates.
[0019] When the installation is provided with a device placed
before the mixing device for the purpose of recovering organic
material from domestic waste, which recovering device comprises
means for removing non-combustible fractions and/or means for
drying the waste, domestic refuse can hereby also be processed into
fuel.
[0020] In addition, the installation can further be provided with a
device for reducing the waste in size placed between the recovering
device and the mixing device.
[0021] In order to enable feed of the different components of the
fuel, the mixing device preferably comprises at least one inlet for
organic material, at least one inlet for a flammable material and
at least one inlet for a binder.
[0022] In order to achieve a sufficient measure of compression, it
is recommended that the pressing device comprises a number of
presses placed in series.
[0023] The pressing device can be provided, in addition or instead,
with means for feeding at least a part of the pressed mixture back
to its inlet.
[0024] The pressing device is further advantageously adapted to
increase the temperature of the mixture.
[0025] These aspects are simple to realize structurally when the
pressing device comprises at least one pellet press with flat die.
Such pellet presses are commercially available from different
suppliers, and enable high pressures and temperatures to be reached
with relatively low energy consumption.
[0026] In addition, the pressing device is advantageously adapted
to generate a pressure and temperature such that the thereby formed
agglomerates can be ground to powder, for instance in a ball mill
or wheel mill.
[0027] The invention will now be elucidated on the basis of an
exemplary embodiment, with reference to the accompanying drawing,
in which:
BRIEF DESCRIPTION OF THE FIGURES
[0028] FIG. 1 is a flow diagram showing schematically the different
steps of the method; and
[0029] FIG. 2 shows a cross-section of a pellet press for use in
this method.
DESCRIPTION OF SPECIFIC REPRESENTATIVE EMBODIMENTS
[0030] Before the present invention is further described, it is to
be understood that this invention is not limited to particular
embodiments described, as such may, of course, vary. It is also to
be understood that the terminology used herein is for the purpose
of describing particular embodiments only, and is not intended to
be limiting, since the scope of the present invention will be
limited only by the appended claims.
[0031] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limit of that range and any other stated or intervening
value in that stated range, is encompassed within the invention.
The upper and lower limits of these smaller ranges may
independently be included in the smaller ranges and are also
encompassed within the invention, subject to any specifically
excluded limit in the stated range. Where the stated range includes
one or both of the limits, ranges excluding either or both of those
included limits are also included in the invention.
[0032] Methods recited herein may be carried out in any order of
the recited events which is logically possible, as well as the
recited order of events.
[0033] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can also be used in the practice or testing of the present
invention, the preferred methods and materials are now
described.
[0034] All publications mentioned herein are incorporated herein by
reference to disclose and describe the methods and/or materials in
connection with which the publications are cited.
[0035] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
referents unless the context clearly dictates otherwise. It is
further noted that the claims may be drafted to exclude any
optional element. As such, this statement is intended to serve as
antecedent basis for use of such exclusive terminology as "solely,"
"only" and the like in connection with the recitation of claim
elements, or use of a "negative" limitation.
[0036] The publications discussed herein are provided solely for
their disclosure prior to the filing date of the present
application. Nothing herein is to be construed as an admission that
the present invention is not entitled to antedate such publication
by virtue of prior invention. Further, the dates of publication
provided may be different from the actual publication dates which
may need to be independently confirmed.
[0037] The conversion into fuel of organic material from for
instance domestic refuse in the manner proposed by the invention
begins with collecting the waste (FIG. 1, block 1). This collected
waste is separated into one or more non-combustible, reusable
fractions R, for instance metals, glass and/or minerals, and a fuel
or RDF fraction F which, in addition to diverse other materials,
can also contain plastics and/or wood (block 3). In order simplify
separation, in the shown embodiment the waste is dried before the
separating step (block 2), for instance to a dry basis content
(d.b.) of more than 80%, and preferably more than 85%. The waste
must in any case be dried to the extent that the moisture content
in the fuel fraction amounts to a maximum of 13%. Once the reusable
fractions R have been separated from fuel fraction F, they are
discharged so that they can be reused. Up to this point the
processing is substantially conventional.
[0038] In order to make the fuel fraction F suitable for burning in
efficient manner, and therefore be able to serve as substitute or
additional fuel in high-efficiency power plants, in particular
pulverized coal power plants, the invention proposes to refine fuel
fraction F. This refining of fuel fraction F begins with reducing
thereof in size, for instance to a particle size of a maximum of 10
mm and preferably a maximum of 5 mm (block 4).
[0039] This reduction is important because a first aspect of the
invention provides for an increase in the calorific value of fuel
fraction F by admixing flammable material C thereto (block 5). Once
the flammable material C has been admixed to the reduced residual
waste, according to a second aspect of the invention this mixture
is compressed to form agglomerates, for instance granules or
pellets (block 6), whereby not only the calorific value per unit of
volume increases further, but also the hardness and
brittleness.
[0040] The materials which according to the invention can be
admixed to the organic material to increase the calorific value
thereof are of very diverse nature. In the first place materials
with a high carbon content can be added, for instance in the form
of ground coke or pure pulverized carbon. Low-sulphur petroleum
coke is recommended in this respect. In addition, combustible
natural materials in accordance with the biomass list, for instance
agricultural products from surpluses, can be added in order to
increase the available quantity of fuel at low cost. A binder is
further added in order to make a cohesive whole of the different
stated components. This binder is adapted to the nature of the
materials in the mixture, and can for instance be a cellulose
binder, or at least a binder based on substances originating from
cellulose.
[0041] The coke can for instance form 20-50% by weight, preferably
30-40% by weight and most preferably 32% by weight of the mixture,
while the content of binder can be 1-20% by weight, preferably
5-14% by weight and most preferably 8% by weight. In this
composition the calorific value of the mixture approximates that of
coal. The elementary composition itself also approximates that of
coal, with a slightly higher content of volatile constituents and a
slightly lower content of ash. The combustion behavior then
corresponds with that of a qualitatively high-grade coal, i.e.
higher than a medium-volatile bituminous coal.
[0042] The elementary composition of the thus obtained fuel can
vary with the supply of the basic materials. An example of average
overall composition can be found in the table below: TABLE-US-00001
NedCoal Specification range of overall values Unit low high Form
Solid Bulk density kg/m3 770 to 790 Density kg/m3 Main elements %
d.b. C 60 to 67 H 5.2 to 6.5 N 1.1 to 1.3 S 1.5 to 3 O (remainder)
20 to 23 Water (% as received) 8 to 11 Volatile 40 to 50 ash
content 8 to 12 net heating value (LHV) MJ/kg 22 to 24 Proportion
of biomass % d.b. 55 to 62 Macro-elements % d.b. Al 1.2 to 1.3 Ca
1.6 to 1.75 Cl 0.2 to 0.4 Fe 0.2 to 0.3 K 0.07 to 0.13 Mg 0.06 to
0.1 Na 0.2 to 0.3 P Si 0.8 to 1 Ti 0.1 to 0.15 Trace elements mg/kg
d.b. Heavy metals As <0.7 Co 3 to 8 Cr 10 to 40 Cu 20 to 80 Mn
30 to 60 Ni 70 to 150 Pb 15 to 80 Sb 3 to 25 V 300 to 550 Ba 35 to
60 Be 0.1 to 0.25 Br Cd <0.4 F 55 to 70 Hg <0.2 Mo Se <1.7
Sn 4 to 7 Te <1.0 Zn 60 to 130 Ti <0.35
[0043] As stated, the method is applicable not only to the fuel
fraction of domestic refuse, but also to organic material from
other sources, for instance wood residues. When such more or less
purely organic material is taken as starting point, the above
described steps 2 and 3 of the method can of course be omitted.
[0044] In order to enable admixture to coal of the mixture still
containing plastics and wood in fuel fraction F in order to
function as fuel in a high-efficiency power plant, processing, in
particular grinding, thereof must be possible in the same manner as
for coal. The invention proposes for this purpose very strong
compression of the mixture, whereby the plastics and the wood
become hard and brittle, and so no longer smeared during grinding.
It is important in this respect that the pressure and temperature
during pressing rise so high and are held for a time at a high
value such that particularly the plastics and the fibrous materials
undergo a change in structure. In combination with the addition of
the binder, this change in structure results in a high degree of
hardness and brittleness and a long storage life of the
agglomerates formed by pressing. Suitable values for the
temperature lie in the order of 60 to 160 C, preferably 80 to 140
C, and more preferably 100 to 120 C. The pressure advantageously
lies in the range of 20 to 45 MPa, preferably between 25 and 40
MPa, and most preferably between 29 and 34 MPa.
[0045] In order to achieve this while making use of relatively
simple pressing equipment and with the supply of a relatively small
amount of energy, the invention proposes to perform the pressing in
a plurality of steps. The mixture can for instance be carried
successively through a number of presses placed in series
(indicated schematically by the subdivision of block 6), but it is
also possible to envisage the mixture being fed back, after the
first pressing operation, one or more times to the inlet of the
press (indicated schematically with a broken line).
[0046] A pellet press with flat die is preferably used as press.
This is a robust press apparatus which enables a relatively long
processing time in the press of the material for pressing. In the
shown embodiment pellet press 10 (FIG. 2) comprises a housing which
consists of an upper part 11 and a lower part 12. Received in the
housing is a flat, annular die 13 which is provided with a large
number of press openings 14 arranged distributed therein. Moving
over die 13 there are a number of press rollers 15, which are each
rotatably mounted on the outer ends of a transverse shaft 16, which
is mounted in turn on a head 17.
[0047] This head 17 is supported by a main shaft 18 which is
rotatably mounted in the housing and which has on its underside a
toothed wheel 19. This toothed wheel 19 is in engagement with a
worm 20 which is driven rotatingly by a motor 21. Further fixed to
the main shaft is a number of scraping knives 22 which move along
the underside of die plate 13.
[0048] The housing is provided on its top side with an inlet
opening 23, while a space 24 under die 13 communicates with an
outlet opening 25.
[0049] The material for pressing is fed through inlet opening 23 to
pellet press 10 and subsequently pressed by means of rollers 15
through openings 14 in die 13. The temperature and pressure in the
material is increased considerably by the friction occurring here.
As they leave these openings 14, the material strands formed
therein are cut into pellets by scraping knives 22, these pellets
finally leaving the press 10 via outlet opening 25. These pellets
can optionally be fed back to inlet opening 23 of press 10, or can
be guided to a subsequent press 10. Once the pellets have obtained
a sufficient hardness and brittleness, they can be admixed to coal
and further processed together therewith.
[0050] When the fuel is intended for use in a pulverized coal power
plant, the further processing includes grinding the fuel pellets in
a ball mill or wheel mill. This creates a powder which can have a
particle size distribution as shown in the following table:
TABLE-US-00002 Smaller than 75 .mu.m c. 65% Smaller than 150 .mu.m
c. 80% Smaller than 300 .mu.m c. 100%
[0051] The invention thus makes it possible with relatively simple
means to convert organic material, which can for instance come from
domestic refuse or equivalent industrial waste, into a fuel
suitable for burning in high-efficiency power plants, for instance
pulverized coal power plants, in addition to or even instead of
coal. The thus formed fuel can of course also be used, even as
primary fuel, in other power plants, for instance gasification
installations, fluidized bed systems and grid boilers.
[0052] Although the invention has been elucidated here on the basis
of an exemplary embodiment, it is not limited thereto, but can on
the contrary be varied in many ways within the scope of the
following claims.
[0053] All publications and patent applications cited in this
specification are herein incorporated by reference as if each
individual publication or patent application were specifically and
individually indicated to be incorporated by reference.
[0054] The preceding merely illustrates the principles of the
invention. It will be appreciated that those skilled in the art
will be able to devise various arrangements which, although
not-explicitly described or shown herein, embody the principles of
the invention and are included within its spirit and scope.
Furthermore, all examples and conditional language recited herein
are principally intended to aid the reader in understanding the
principles of the invention and the concepts contributed by the
inventors to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions. Moreover, all statements herein reciting principles,
aspects, and embodiments of the invention as well as specific
examples thereof, are intended to encompass both structural and
functional equivalents thereof. Additionally, it is intended that
such equivalents include both currently known equivalents and
equivalents developed in the future, i.e., any elements developed
that perform the same function, regardless of structure. The scope
of the present invention, therefore, is not intended to be limited
to the exemplary embodiments shown and described herein. Rather,
the scope and spirit of present invention is embodied by the
appended claims.
* * * * *