U.S. patent application number 10/228721 was filed with the patent office on 2003-08-14 for apparatus and method for fractionating alternative solid fuels.
Invention is credited to Berrun-Castanon, Jorge, Cantun-Martinez, Hector Agustin, Cuevas-Martinez, Angel, Farias-Martinez, Luis Ramon, Garcia-Segovia, Armando, Garza-Ondarza, Jose Javier.
Application Number | 20030150161 10/228721 |
Document ID | / |
Family ID | 46281083 |
Filed Date | 2003-08-14 |
United States Patent
Application |
20030150161 |
Kind Code |
A1 |
Garcia-Segovia, Armando ; et
al. |
August 14, 2003 |
Apparatus and method for fractionating alternative solid fuels
Abstract
An apparatus and a method fractionate solid fuels, especially
whole tires, into metal as well as volatiles and coal to be used as
alternative fuels. The apparatus includes a feeding zone wherein
the solid fuels are fed to the apparatus, a gasifying zone into
which the solid fuels are processed, obtaining a gaseous fraction,
coal, and metal; cooled grills controlling the bed permeability and
permanence time of the solid fuels at the gasifying zone; and a
discharging zone into which the resultant coal and metal are
discharged, in which the solid fuel coal and solid and gaseous
fractions follow a path inside the apparatus through the feeding
zone, the gasifying zone and discharging zone, and in which the
gases inside the apparatus follow a path that is co-current with
the solid fuel fractions path inside the apparatus.
Inventors: |
Garcia-Segovia, Armando;
(Nuevo Leon, MX) ; Farias-Martinez, Luis Ramon;
(Nuevo Leon, MX) ; Garza-Ondarza, Jose Javier;
(Nuevo Leon, MX) ; Berrun-Castanon, Jorge; (Nuevo
Leon, MX) ; Cantun-Martinez, Hector Agustin; (Nuevo
Leon, MX) ; Cuevas-Martinez, Angel; (Nuevo Leon,
MX) |
Correspondence
Address: |
ABELMAN, FRAYNE & SCHWAB
150 East 42nd St.
New York
NY
10017-5612
US
|
Family ID: |
46281083 |
Appl. No.: |
10/228721 |
Filed: |
August 26, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10228721 |
Aug 26, 2002 |
|
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09389851 |
Sep 2, 1999 |
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Current U.S.
Class: |
48/62R ;
422/184.1; 422/187; 422/198; 422/600; 48/119; 48/197FM; 48/197R;
48/61; 48/89 |
Current CPC
Class: |
F23H 3/02 20130101; C10J
3/16 20130101; Y02P 20/144 20151101; F23G 2207/112 20130101; C10J
2300/1223 20130101; C10J 2200/154 20130101; F23G 5/027 20130101;
Y02P 20/143 20151101; F23G 2207/113 20130101; C10J 3/30 20130101;
F23G 2209/281 20130101; F23G 5/50 20130101; F23G 7/12 20130101;
C10J 2300/1671 20130101 |
Class at
Publication: |
48/62.00R ;
48/61; 48/89; 48/119; 48/197.00R; 48/197.0FM; 422/184.1; 422/187;
422/188; 422/189; 422/198 |
International
Class: |
C10J 003/20 |
Claims
What is claimed is:
57. An apparatus for fractionating solid fuels into a gaseous
fraction, a coal fraction, and a non-coal fraction, which
comprises: a) gasifying means including a first end and a second
end; b) a feeding zone at the first end of the gasifying means; c)
a solid fuels feeding means, placed at the feeding zone of the
gasifying means, to control feeding of solid fuels; d) a gasifying
zone coupled to the feeding zone wherein partial combustion takes
place; e) air feeding means connected to the gasifying zone for
feeding air for the partial combustion of solid fuels, including a
hot air input from a suitable source at the gasifying zone in order
to control the temperature thereof; f) retaining means in the
gasifying zone for controlling permeability and residence time of
the solid fuels in the gasifying zone, including cooling means
located inside the retaining means to avoid melting of the solid
fuel on the retaining means; g) driving means for the retaining
means adapted to completely put or withdrawn said retaining means
for discharging the coal fraction and the non-coal fraction after
complete separation of the gaseous fraction of the solid fuels and
for continuously discharging solids and avoiding formation of
agglomerates in the gasifying means; h) a gas exhaust into which
the gaseous fraction is discharged from the gasifying zone for
further use; i) a discharging zone coupled to the gasifying zone;
and j) discharging means at the discharging zone which receives the
coal fraction and the non-coal fraction from the gasifying zone and
which discharges the coal fraction and the non-coal fraction from
the discharging zone; wherein the solid fuel coal, solid and
gaseous fraction follow a path inside the apparatus through the
feeding zone, the gasifying zone and discharging zone, and wherein
the air feeding means, provide an air current that is co-current
with the solid fuels fractions path inside the apparatus.
58. An apparatus for fractionating whole tires having tire beads of
steel wire into a gaseous fraction, a coal fraction, and a non-coal
fraction, which comprises: a) gasifying means including a first end
and a second end; b) a feeding zone at the first end of the
gasifying means; c) a whole tire feeding means, placed at the
feeding zone of the gasifying means to control the feeding of the
whole tires; d) a gasifying zone coupled to the feeding zone
wherein partial combustion of the whole tires takes place; e) air
feeding means connected to the gasifying zone for feeding air for
the partial combustion of the whole tires, including a hot air
input from a suitable source at the gasifying zone in order to
control the temperature thereof; f) retaining means in the
gasifying zone for controlling permeability and residence time of
the whole tires in the gasifying zone, including cooling means
located inside the retaining means to avoid melting of the whole
tires on the retaining means; g) driving means for the retaining
means adapted to completely put or withdrawn said retaining means
for discharging the coal fraction and the non-coal fraction after
complete separation of the gaseous fraction of the whole tires and
for continuously discharging steel wire and other solids and
avoiding formation of agglomerates in the gasifying means; h) a gas
exhaust into which the gaseous fraction is discharged from the
gasifying zone for further use; i) a discharging zone coupled to
the gasifying zone; and j) discharging means at the discharging
zone which receives the coal fraction and the non-coal fraction
from the gasifying zone and which discharges the coal fraction and
the non-coal fraction from the discharging zone; wherein the whole
tire coal, solid and gaseous fraction follows a path inside the
apparatus through the feeding zone, the gasifying zone and
discharging zone, and wherein the air feeding means, provide a hot
air current that is co-current with the solid fuels fractions path
inside the apparatus.
59. The apparatus according to claim 57, wherein the solid fuels
feeding means comprise a feeding valve including driving means to
open and close said feeding valve.
60. The apparatus according to claim 57, wherein the solid fuels
feeding means comprise a plurality of gates in which solid fuels
are fed.
61. The apparatus according to claim 57, wherein the retaining
means comprise a plurality of grills.
62. The apparatus according to claim 57, wherein the cooling means
of the retaining means include internal pipes inside the retaining
means into which cool water is circulated by means of a pump.
63. The apparatus according to claim 57, wherein the cooling means
of the retaining means include internal pipes inside the retaining
means into which cool air is circulated by means of a pump.
64. The apparatus according to claim 57, wherein the driving means
for the retaining means comprise hydraulic motors alternately
introduce or withdraw said retaining means.
65. The apparatus according to claim 57, wherein the solid fuels
feeding means feeds the solid fuel to the gasifying zone, by a
hydraulic piston and cylinder assembly.
66. The apparatus according to claim 57, wherein the discharging
means discharge the coal fraction and the non-coal fraction from
the gasifying zone, by a hydraulic piston and cylinder
assembly.
67. The apparatus according to claim 57, wherein the discharging
means discharges the coal fraction and the non-coal fraction from
the discharging zone to outside of the apparatus, by gravity.
68. The apparatus according to claim 57, wherein the discharging
means discharges the coal fraction and the non-coal fraction from
the discharging zone to outside of the apparatus, by a hydraulic
piston and cylinder assembly.
69. The apparatus according to claim 57, wherein the discharging
valves include driving means which open and close said discharging
means in order to discharge the coal fraction and the non-coal
fraction from the apparatus.
70. The apparatus according to claim 57, wherein the air feeding
means include a hot air input which takes hot air from a tertiary
air duct of a cement kiln, and the gas exhaust means discharges the
gaseous fraction to a pre-calcinator or calcinator section of the
cement kiln to substitute primary fuel, and the coal fraction to a
kiln input to substitute primary fuel and the non-coal fraction is
integrated to a cement clinker.
71. The apparatus according to claim 57, wherein the discharging
means discharges the non-coal fraction to a feeding conveyor belt
of a kiln for producing cement.
72. The apparatus according to claim 57, wherein the discharging
means discharges the coal fraction to a main burner of a kiln for
producing cement.
73. The apparatus according to claim 57, wherein the air feeding
means include a hot air input which takes hot air from a cement
clinker cooler and the discharging means discharge the non-coal
fraction outside of the gasifying means, to containers for an
application to a recuperator of a cement kiln having no
pre-calcinator.
74. The apparatus according to claim 57, wherein the discharging
means discharge the coal fraction into a main burner of a cement
kiln having no pre-calcinator.
75. The apparatus according to claim 58, wherein the gasifying
means comprises a vertical column.
76. The apparatus according to claim 58, wherein the whole tire
feeding means valve comprise a feeding valve including driving
means to open and close said feeding valves.
77. The apparatus according to claim 58, wherein the whole tire
feeding means comprises a plurality of gates in which whole tires
are fed.
78. The apparatus according to claim 58, wherein the retaining
means comprise a plurality of grills.
79. The apparatus according to claim 58, wherein the retaining
means comprising a mesh and wherein the cooling means of the
retaining means include internal pipes inside said mesh, into which
cool water is circulated by means of a pump.
80. The apparatus according to claim 58, wherein the driving means
for the retaining means comprise hydraulic motors to alternately
introduce or withdraw said mesh.
81. The apparatus according to claim 58, wherein the discharging
means comprise a plurality of gates.
82. The apparatus according to claim 58, wherein the discharging
means include driving means.
83. The apparatus according to claim 82, wherein the driving means
of the discharging means comprises hydraulic motors which raise and
lower said discharging means.
84. The apparatus according to claim 58, wherein whole tire feeding
means feed the whole tires to the gasifying zone by gravity.
85. The apparatus according to claim 58, wherein the whole tire
feeding means feeds the whole tires to the gasifying zone by a
hydraulic piston and cylinder assembly.
86. The apparatus according to claim 58, wherein the discharging
means discharge the coal fraction and the non-coal fraction from
the gasifying zone to the discharging zone by gravity.
87. The apparatus according to claim 58, wherein the discharging
means discharges the coal fraction and the non-coal fraction from
the gasifying zone by a hydraulic piston and cylinder assembly.
88. The apparatus according to claim 58, wherein the discharging
means discharges the coal fraction and the non-coal fraction from
the discharging zone to outside of the apparatus by gravity.
89. The apparatus according to claim 58, wherein the discharging
means discharges the coal fraction and the non-coal fraction from
the discharging zone to outside of the apparatus by a hydraulic
piston and cylinder assembly.
90. The apparatus according to claim 58, wherein the discharging
valves include driving means which open and close the discharging
means in order to discharge the coal fraction and the non-coal
fraction from the apparatus.
91. The apparatus according to claim 58, wherein the hot air input
of the air feeding means takes hot air from a tertiary air duct of
a cement kiln, the gaseous fraction is discharged through the gas
exhaust to a pre-calcinator or calcinator section of the cement
kiln to substitute primary fuel, and the coal and non-coal
fractions are discharged through the discharging zone by the
discharging means to a kiln input to substitute the primary fuel
and integrated into a cement clinker respectively.
92. The apparatus according to claim 58, wherein the discharging
means discharges the non-coal fraction to a feeding conveyor belt
of a cement kiln.
93. The apparatus according to claim 58, wherein the discharging
means discharges the coal fraction to a main burner of a cement
kiln.
94. The apparatus according to claim 58, wherein the air feeding
means includes a hot air input which takes hot air from a cement
clinker cooler and the discharging means discharge the non-coal
fraction outside of the gasifying means, to containers for an
application to a recuperator of a cement kiln having no
pre-calcinator.
95. The apparatus according to claim 58, wherein the discharging
means discharges the coal fraction into a main burner of a cement
kiln having no pre-calcinator for producing cement.
96. The apparatus according to claim 58, wherein the apparatus
operates at a temperature of between about 900.degree. C. and about
1150.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 09/389,851, filed Sep. 2, 1999, now
abandoned.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to an apparatus and a method for the
recovery of energy from solid waste by combustion of the solid
waste in industrial kilns, and more particularly to an apparatus
and a method for fractionating alternative solid fuels, especially
tires, into metal as well as volatile gases and coal to be used as
alternative fuels.
[0004] 2. Description of the Related Art
[0005] Since 1980, hazardous solid wastes, such as discarded tires
from many kinds of vehicles, have been used as alternative or
supplemental fuel in kilns for the production of cement.
[0006] The necessity of reducing total fuel costs through the
substitution of waste-derived fuels instead of normal fossil fuels,
primarily coal, has been the main incentive behind the search of
cheap alternative fuels to fire industrial kilns such as kilns for
producing cement.
[0007] The most readily usable non-hazardous wastes having the
highest heat content consist of discarded tires. It is estimated
that there are about 36 cement plants in the United States
utilizing tire-derived fuel.
[0008] Whole tires, tires ground into "crumb", and tire chips are
used as fuel with essentially similar results.
[0009] Tires grounded into "crumb" have the following advantages:
1) the generation of the crumb from the tires allows the steel in
the bead and radial bands to be removed by air classification; 2)
the crumb can be blown inside the kiln together with powdered coal
fuel, thus substituting a part of the powdered coal as the main
fuel source; and 3) the transportation storage and management of
the crumb is very similar to the managing of coal fines.
[0010] There are however some disadvantages when using crumb for
producing cement: 1) the removal of steel wires from crumb is very
difficult, notwithstanding that processes for producing cement need
iron; and 2) producing crumb is quite expensive, giving the crumb a
price as high as coal or coke.
[0011] Tires "chips" of many sizes are normally used as fuel in
kilns for producing cement. These chips range in sizes varying from
2 cm..times.2 cm. to 15 cm..times.15 cm. For any chip size, the
transportation, storage, and management costs are essentially the
same. Transportation is carried out by truck, and chips are
accumulated in large piles in the open, similar to the storage
methods of coal or limestone. The feeding of the chips into the
kiln is carried out by means of a conveyor fed from a hopper. A
front end loader is used to load the hopper from the storage
pile.
[0012] The use of tire chips as fuel has some advantages: 1) the
feed rate may be continuously monitored and carefully controlled;
and 2) there is very little manual labor involved in handling chips
versus whole tires.
[0013] There are, however, some disadvantages when using tire
chips: 1) the production of chips from whole tires is expensive,
certainly not as costly as the production of crumb, but production
often represents half the cost of acquiring and delivering the
supplemental fuel; and 2) the steel wire from the bead and radial
belts of the tires does not shear off smoothly when the tires are
chipped, and consequently the chips are ragged and the steel wires
may hook everything they come into contact with, making the
facility operation difficult.
[0014] The use of whole tires as fuel in kilns for producing cement
is also common in the cement industry. Tires are delivered by
trucks at the end of a conveyor, and then tires are manually
unloaded from the truck onto the conveyor. The conveyor feeds the
tires to a mechanism that inserts one tire at a time into the kiln
at specified time intervals. The main advantage of using whole
tires is that there are no processing costs in addition to the
acquisition costs. In addition, unlike tire chips, the whole tires
do not "fly" throughout the facility nor have the possibility of
causing possible "dust fires", like the crumb.
[0015] However, despite the above advantages, the use of whole
tires generates some problems related to the removal of steel wire
from the gasifier section of the kiln, in which the steel wire
tends to get entangled into the gasifier, forming a great tangle of
wire, affecting the flow of volatiles from the combustion chamber
to the kiln or calcinator, decreasing the fuel substitution
percentage and limiting the use of whole tires as supplemental
fuel.
[0016] Therefore, since whole tires are the most reliable and
economic alternative fuel, it would be highly desirable to have a
method and apparatus that could solve the above referred
problems.
[0017] In recent years, there have been developed a number of
methods and apparatuses for the recovery of energy from waste
material, especially for kilns for producing cement, which are
specially adapted to use tires (both grounded or whole tires) as a
fuel substitute in the range of 5% to 25% at best, depending on the
type of kiln, fuel, and feeding points.
[0018] U.S. Pat. No. 4,627,877 to Ogawa et al. discloses a method
and apparatus for continuously producing a cement clinker by using
a waste material as a fuel for preheating or calcinating a cement
material, by using an apparatus comprising a cement material
feeder, a preheater or calcinator, a rotary kiln, a cooler, and
means for flowing an exhaust gas from the rotary kiln to the
preheater or calcinator. The apparatus is characterized by
including a heat-decomposer which is located between the preheater
or calcinator and the rotary kiln, in which a combustible material
is heat decomposed by a hot gas exhausted from the rotary kiln and
the resultant combustible gas is burnt in the preheater or
calcinator substituting a part of the primary fuel therein. Ogawa's
method has the limitation that it is only able to use grounded
tires since it does not have any means to prevent entanglements of
wire or means to remove the wire which is released when using whole
tires. Furthermore, Ogawa's method does not show any means to
control the bed permeability and permanence of the grounded tire at
the calcination point which would be highly desirable since
controlling the permanence time and permeability of the bed will
allow a complete calcination of the tire and an adequate production
and flow of the volatiles to the point of combustion.
[0019] U.S. Pat. No. 4,640,681 to Steinbiss et al. discloses a
method and apparatus for the disposition of hazardous and waste
materials of low heat content, for example, refuse, by means of a
combustion process which is carried out in a furnace, by the
presence of added hot combustion air at a sufficient temperature so
that the combustion and/or flue gas temperatures are at least
1,250.degree. C.
[0020] In a preferred embodiment of the invention, the combustion
process is combined with a process for the production of cement
clinker and is carried out parallel to the same, wherein air at
about 800.degree. C. is branched off for combustion of the
hazardous substances from the cooler air of the cement clinker
installation and introduced into the furnace. The hot flue gas of
the combustion in the furnace is directed into the cement clinker
installation.
[0021] Although in the Steinbiss patent it is possible to control
the permanence time of the waste materials in the furnace, this
method and apparatus is not intended for whole tires and it is a
fluidized bed gasifier. Therefore it can not gasify whole tires and
discharge the wire. Furthermore, since the main objective of this
invention is the disposition of hazardous and waste materials, it
is designed to use only waste materials of low heat content,
therefore the quality and quantity of volatile produced is very low
and cannot be considered as a suitable supplemental fuel for
industrial kilns.
[0022] Furthermore, it is clear that the Steinbiss apparatus is not
designed to efficiently gasify materials due to the following
reasons:
[0023] 1. The operating temperature of the Steinbiss apparatus and
method would produce liquid phases of the materials which would
adhere to the furnace walls.
[0024] 2. The Steinbiss apparatus and method neither teach nor
disclose a method for continuously discharging the waste
material.
[0025] 3. The Steinbiss grate does not disclose cooling means for
avoiding the melting of material on the grate.
[0026] U.S. Pat. No. 5,636,581 of Kleen discloses: a plurality of
fluid-cooled grate bars, each said grate bar having a duct
extending substantially longitudinally therewithin for guiding a
first coolant, each said duct having an inlet and outlet opening
for feeding and discharging the first coolant, said plurality of
grate bars being arranged in adjacent alternately stationary and
moveable rows; and a main fluid inlet line and a main fluid outlet
line, each said inlet and outlet opening of each said duct of each
said grate bar being connected with said main fluid inlet line and
said main fluid outlet line, respectively, wherein said plural
grate bars are connected in parallel to the main fluid inlet line
and the main fluid outlet line for fluid communication
therewith.
[0027] It should be noted that Kleen's cooled grate is unable to
handle the wire from whole tires because Kleen's cooled grill is
intended to be used in garbage incinerators, having adjacent rows
of alternately stationary and mobile grate bars and it does not
disclose or even suggest any structural element that is capable of
preventing the entanglement of wire when burning tires.
Furthermore, the purpose of the cooling means of Kleen's grill is
to cool the grate in order to minimize wearing of the grate and
avoiding structural collapse. The cooling means are not designed
nor are they capable of lowering the temperature of the gate
surface so as to avoid the melting of material on the grate.
[0028] U.S. Pat. No. 4,256,503 to Tsuda et al. discloses a method
for effectively utilizing waste tires in an apparatus for burning
cement by means of a rotary kiln, comprising the steps of; charging
waste tires crushed or without crushing as fuel directly into the
back end of the kiln, to a position in said kiln wherein the gas
temperature is 600.degree. C. to 1,400.degree. C., in an amount not
exceeding 60% of the total fuel calculated as heat energy. The main
disadvantage of this method is that the heat released by the
combustion of volatiles would overheat the back end of the kiln and
would induce the formation of very hard agglomerates which are very
difficult to remove.
[0029] U.S. Pat. No. 4,110,121 to Rechmeir et al. discloses a
process for producing cement clinker in which raw meal is fed to a
heat exchanger, heat is supplied to the heat exchanger from a
downstream kiln, the raw meal is heated in the heat exchanger and
the heated raw meal is conveyed to the kiln and sintered therein by
the use of a fuel to form the cement clinker, the improvement
comprises using high grade waste fuel formed from organic waste in
the form of tires, rubber scrap, or plastics scrap and wherein the
waste fuel is processed before combustion by pyrolysis to form
pyrolysis gases and a pyrolyzed residue and said pyrolyzed residue
is comminuted or gasified. Although the Rechmeir process discloses
the separation of the residual carbon form tires, it does not
disclose the separation of the wire or the management of the wire
into the pyrolyzer, which would limit the use of whole tires.
[0030] U.S. Pat. No. 5,226,774 to Tutt et al. discloses an
apparatus for controlling the input of combustible solids through a
port formed in a wall of a rotary kiln cylinder of an operating
cement kiln at a location between an upper end and a lower fired
end thereof, the kiln containing hot mineral material for
combustion of said combustible solids in contact with said mineral
material. In Tutt's apparatus, the tires are directly feed into the
kiln, and therefore the disadvantages are similar to those of
Tsuda's method.
[0031] U.S. Pat. No. 4,627,877 to Ogawa et al. discloses a method
and apparatus for continuously producing a cement clinker
comprising the steps of: feeding a cement material into a
preheating or calcinating region; preheating or calcinating said
fed cement material in a predetermined temperature range;
forwarding said preheated or calcinated cement material into a
heating region; heating said preheated or calcinated cement
material at a predetermined temperature to convert said cement
material to a cement clinker; moving said cement clinker into a
cooling region; cooling said cement clinker with cooling air to a
decreased temperature, and; flowing an exhaust gas from said
heating region through said preheating or calcinating region, which
method is characterized by the steps of: feeding a combustible
material into a heat-decomposing region located between said
heating region and said preheating or calcinating region;
introducing at least a portion of said exhaust gas from said
heating region into said heat-decomposing region to heat-decompose
said combustible material and to generate a combustible gas
therefrom; introducing said combustible gas from said
heat-decomposing region into said preheating or calcinating region,
and; burning said combustible gas in said preheating or calcinating
region to preheat or calcinate said cement material.
[0032] If there were applied cooled grills (as in Kleen's patent)
under the operating conditions of Ogawa's method, the kiln gas
would flow countercurrent to the feeding path through the gasifying
zone, thus causing low melting compounds carried by the kiln gas
(Na.sub.2O, Na.sub.2SO.sub.4, K.sub.2SO.sub.4, etc) to go up and
solidify and form mineral deposits on the grill. Such deposits
would avoid the movement of the cooled grill for discharging the
wire.
[0033] Furthermore, since the hot kiln gas would reach the cooled
grills, the wire would frequently melt on the grill and on the
refractory walls.
BRIEF SUMMARY OF THE INVENTION
[0034] Applicant carried out several tests in bench scale models
using countercurrent models and the melting of the wire happened
twice as many times as the co-current model. Therefore, it is much
easier to control the gasifier to minimize wire melting when it is
operated with the air flowing concurrently with the solid fuel.
[0035] The change from countercurrent to co-current is very
important since a person having an ordinary skill in the art would
say that a countercurrent gasifier is kinetically and
thermodynamically superior than a co-current one. However, in view
of the results obtained by applicant's experiments, one can
conclude that the co-current model has advantages over the prior
art countercurrent model.
[0036] Since chemical engineers know that a countercurrent heat
exchanger is more efficient than a co-current one, the fact that a
co-current gasifier has advantages over a countercurrent one has to
be proved by means of experimentation. The aforesaid
experimentation shows that the development of the co-current
concept and model is not obvious.
[0037] Therefore, if a person skilled in the art propose to combine
Steinbiss's, Ogawa's and Kleen's designs in order to produce an
apparatus for gasifying whole tires, the resulting design would not
work properly because the countercurrent model causes the melting
of the wire on the cooled grill. Also, the use of hot gas form the
kiln, carrying low melting point compounds produce build ups on the
cooled grills that causes a lot of operation problems.
[0038] Finally, it should be noted that:
[0039] 1. None of the apparatuses and methods disclosed in the
Steinbiss, Kleen and Ogawa patents are capable of continuously
fractionating whole tires while discharging the wire thereof,
without entangling the wire inside the apparatus, and while
achieving a fuel substitution of greater than 10%.
[0040] 2. None of the references disclose the capability of
avoiding hot spots, reducing atmospheres and build-ups which are
observed when the coal and wire are discharged in the kiln after
the combustion of whole tires.
[0041] Note should also be taken that even considering the
combination of the above referred patents, they do not teach,
disclose or suggest how to achieve an apparatus for fractionating
alternative solid fuels (especially whole tires) having the
following characteristics:
[0042] 1. Having the capacity of continuously fractionating whole
tires without wire entanglements due to the mesh which allows for
the continuous discharge of wire from the apparatus.
[0043] 2. Wherein the mesh for controlling the residence time of
the material to be burned at the gasifying zone have cooling means
for cooling the surface of the gates and avoiding the melting of
the material on the gate when burned.
[0044] 3. Capability of achieving a fuel substitution percentage of
greater than 10%, without the formation of build-ups.
[0045] 4. Ability to avoid secondary effects, such as the formation
of hot spots or reducing atmospheres.
[0046] 5. Easily adaptable to any type of industrial kiln.
[0047] Considering the above referred problems, applicants
developed an apparatus and a method for fractionating alternative
solid fuels, especially whole tires, into volatiles and coal, to be
used as alternative fuels, and metal, which uses the co-current
model.
[0048] Applicant's apparatus and method provide means to separate
the residual carbon and volatile of burned solid fuels, as well as
the wire produced by the combustion of the whole tires.
Furthermore, there are included means to control the permanence
time of the solid fuel at the gasifying zone of the apparatus,
which can be optimized for each type of solid fuel.
[0049] Applicant's apparatus comprises a main column having a
feeding zone, including one or more feeding valves; a hot air
input, providing a hot air current that follows the same path as
the solid fuels inside the gasifier; driving means are provided for
opening and closing said feeding valves; a gasifying zone located
below the feeding zone, having a cool air input coming from a
suitable source such as an air pump; If possible an input for hot
air which is used for the combustion of the solid fuels, coming
from a suitable source; one or more alternately introduced and
withdrawn cooled grills controlling the permeability and permanence
time of the solid fuels at the gasifying zone; a gasifier duct in
which the volatiles are discharged from the gasifying zone to the
main burner or other suitable zone of the kiln or pre-heater
wherein the apparatus of the present invention will be used; a
discharging zone located below the gasifying zone having one ore
more discharging valves which receive the coal and solids coming
from the gasifier and which are opened at a convenient time in
order to discharge the coal and solids from the apparatus; and a
discharging opening situated below the discharging valves.
[0050] Applicant's apparatus uses the co-current model in which the
air follows the same direction as the solid fuels inside the
gasifier, avoiding the return of hot air form the kiln carrying low
melting point compounds which may solidify on the cooled grills and
avoiding the melting of wire on the cooled grills and on the walls
of the gasifier.
[0051] Applicant's method comprises: providing an apparatus
including a gasifier wherein the solid fuels will be partially
burned and the volatiles will be emitted; feeding the alternative
solid fuel to the gasifying zone of the apparatus; providing a hot
air current that follows the same path as the solid fuels inside
the gasifier; providing cool air to the gasifier and if possible
hot air from a suitable source; partially burning the alternative
solid fuels into the gasifying zone until most of the volatiles
have been emitted, coal with a minimum content of volatiles is
obtained, and the non combustible solids are separated; discharging
the volatiles from the gasifier for further use; and discharging
the resultant coal and solids from the gasifier by gravity or any
other known means.
[0052] With applicant's apparatus and method, the fuel substitution
percentage achieved can be higher than 40%, which is higher than
the fuel substitution percentages achieved by the actual known
methods and apparatuses.
[0053] It is therefore a main objective of the present invention,
to provide an apparatus and a method for fractionating alternative
solid fuels that uses the air flow co-current model inside the
gasifier.
[0054] It is also a main objective of the present invention to
provide an apparatus and method for fractionating alternative solid
fuels, of the above disclosed nature, which provide means to
separate the volatiles and the residual coal, to be used as
alternative fuels, and the non combustible solids, produced by the
partial combustion of the solid fuels.
[0055] It is another objective of the present invention to provide
an apparatus and method for fractionating alternative solid fuels,
of the above disclosed nature, which provide means to separate the
wire produced by the combustion of whole tires.
[0056] It is also a main objective of the present invention to
provide an apparatus and method for fractionating alternative solid
fuels, of the above disclosed nature, which include means to
control the permanence time of the solid fuel at the calcination
point, to be optimized for each type of solid fuel.
[0057] It is still another objective of the present invention to
provide an apparatus and method for fractionating alternative solid
fuels, of the above disclosed nature which includes means for
controlling permeability.
[0058] It is still a main objective of the present invention to
provide an apparatus and method for fractionating alternative solid
fuels, of the above disclosed nature, in which fuel substitution
percentage achieved is higher than 40%, which is higher than the
fuel substitution percentages achieved by the actual methods and
apparatuses.
[0059] These and other objects and advantages of the apparatus and
method for fractionating alternative solid fuels, of the present
invention will become apparent to those persons having an ordinary
skill in the art, from the following detailed description of the
embodiments of the invention which will be made with reference to
the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0060] FIG. 1 is a front view of the apparatus for fractionating
alternative solid fuels of the present invention.
[0061] FIG. 2 is a diagram of a cement plant, including the
apparatus for fractionating alternative solid fuels of the present
invention in a first embodiment of use.
[0062] FIG. 3 is a diagram of a cement plant, including the
apparatus for fractionating alternative solid fuels of the present
invention in a second embodiment of use.
[0063] FIG. 4 is a diagram of a cement plant, including the
apparatus for fractionating alternative solid fuels of the present
invention in a third embodiment of use.
[0064] FIG. 5 is a diagram of a cement plant, including the
apparatus for fractionating alternative solid fuels of the present
invention in a fourth embodiment of use.
[0065] FIG. 6 is a diagram of a cement plant, including the
apparatus for fractionating alternative solid fuels of the present
invention in a fifth embodiment of use.
[0066] FIG. 7 is a diagram of a thermoelectrical plant, including
the apparatus for fractionating alternative solid fuels of the
present invention as another embodiment of use.
[0067] FIG. 8 is a top view of the mesh/grill of the present
invention showing the cooling means.
DETAILED DESCRIPTION OF THE INVENTION
[0068] The invention will be described referring to a preferred
embodiment thereof, illustrated in the accompanying drawings
wherein the same signs and numbers, refer to the same parts of the
shown figures.
[0069] Referring to FIG. 1, the apparatus for fractionating
alternative solid fuel includes:
[0070] gasifying means having a main column 1 having a first end 2
and a second end 3, and including:
[0071] a feeding zone F, having:
[0072] valve means including one or more feeding valves comprising
gates 4, 4', located at the feeding zone F, in which the solid
fuels S are fed, and which are opened and closed for a convenient
time and sequence in order to feed the solid fuels S to the place
wherein the combustion will take place;
[0073] driving means for the feeding valves (not shown) which could
be hydraulic motors, for opening and closing said feeding valves
4,4';
[0074] a gasifying zone G located below the feeding zone F,
having:
[0075] input means for hot air 5 which is used for the combustion
of the solid fuels S, coming from a suitable source (not
illustrated) which could be, in case of applying the present
invention to a rotary kiln for producing cement, the tertiary air
duct or the clinker cooler, with such input means providing a hot
air current that is co-current with the path that follow the solid
fuels inside the apparatus;
[0076] input means 6 for cool air coming from a suitable source
such as an air pump;
[0077] retaining means comprising one or more alternately
introduced and withdrawn cooled mesh and/or grills 7, 7', 7" having
internal pipes P as cooling means, such as mesh 7 with pipes P
shown in FIG. 8; and
[0078] driving means 20, such as motors and/or pumps, are capable
of substantially and/or totally introducing and/or withdrawing the
mesh and/or grills, such as grill 7 in FIG. 8, into the pathway of
the materials, with substantial and/or total withdrawal allowing
the processed tires to pass through the pathways of the apparatus
unobstructed and to avoid build-up and/or clogging of material in
the pathways, with cool air or water is circulated into the pipes P
by means of a pump, said cooled grills controlling the bed
permeability and permanence time of the solid fuels S at the
gasifying zone G and are able to be withdrawn in order to discharge
the coal and solids, after the separation of volatile and solids is
achieved, to a discharging zone D avoiding the melting of wire or
any matter on the grills, with the driving means 20 for the cooled
grills, as shown in FIG. 8, which operatively introduce or withdraw
said cooled grills 7, 7', 7";
[0079] a duct 8 into which volatiles are discharged from the
gasifying zone G for further use, said volatiles serving as
supplemental fuel;
[0080] a discharging zone D located below the gasifying zone G
having:
[0081] valve means including one ore more discharging valves
comprising gates 9, 9' which receive the coal C and solids, such as
wire W, coming from the gasifier G and which are opened at a
convenient time in order to discharge the coal and solids C from
the apparatus; and
[0082] a discharging opening H located below the discharging valves
or gates 9, 9' to discharge the coal C and solids, such as wire W,
from the apparatus.
[0083] It is to be understood that the gasifying means may be a
vertical column wherein the feeding zone, the gasifying zone and
the discharging zone are placed in a downwardly sequence, or else,
it can be a horizontal chamber wherein the feeding zone, the
gasifying zone and the discharging zone are placed in a side by
side fashion, and in this embodiment it would be needed a
mechanical feeding device including an hydraulic cylinder and
piston assembly (not shown).
[0084] The apparatus of the present invention, operating at a
temperature between about 900.degree. C. and about 1150.degree. C.,
can be used for fractionating continuously batches of supplemental
fuel, such as whole tires, so that when a first batch of burning
material is placed at the feeding valves 4,4' which are initially
closed, a second batch may be already at the gasifying zone G,
wherein the cooled grills 7, 7', 7" are sequentially opened at
predetermined times, depending on the characteristics, such as
size, of the supplemental fuel being processed, thus controlling
the bed permeability and permanence time, and avoiding the
formation of agglomerates inside the apparatus. The grill cooling
means (not shown) avoid that the pipes forming the grill lose
mechanical properties due to overheating or corrosion.
[0085] When the last cooled grill is opened 7", if the apparatus
has more than one grill, the resultant coal C and solids, such as
wire W, are discharged to the discharge valve 9, which is opened at
a convenient time as well as the other discharge valves 9', in case
that the apparatus has more than one discharge valve, when a
predetermined amount of coal C and solids W are obtained.
[0086] The last feeding valve 4' is opened discharging the
supplemental fuel to the first cooled grill 7, as soon as this is
emptied.
[0087] Therefore, the apparatus of the present invention can be fed
with whole tires, without problems such as wire entangling,
obtaining a complete separation of volatile, coal and wire.
[0088] Although it was mentioned that the apparatus of the present
invention has an input of hot air 5, it is also suitable to operate
without a hot air input when there is not available.
[0089] As it was mentioned, one of the applications of the present
invention is at the cement industry, in which the installation of
the present apparatus is at a rotary cement kiln or calcinator,
using whole or shredded tires as supplemental fuel.
[0090] Referring to FIG. 2, a first possible embodiment of use of
the apparatus of the present invention R, at a rotary cement kiln,
is by installing the apparatus at the back end of the cement kiln,
feeding the apparatus with whole or shredded tires T, injecting air
form the atmosphere A, taking hot air from the tertiary air duct
19, if the kiln has a tertiary air duct, and discharging the
volatiles V to the pre-calcinator or calcinator 10 to substitute
primary fuel M, and discharging wire W and tire coal C to the kiln
input 11 to substitute primary fuel. The wire is integrated to the
clinker K, substituting part of the iron required in the form of an
oxide. The main advantages of this form of use are that the
volatiles are burned where it is required. Therefore there is less
tendency to form hot points and agglomerates at the input of the
kiln, than in the case in which all the alternative fuel is
directly fed to the kiln.
[0091] Referring to FIG. 3, a second possible embodiment of use, is
as described in the first one, but additionally discharging the
wire W to the outside of the apparatus and of the rotary kiln 12,
to containers or to a conveyor belt (not shown). This way of use is
suitable for the production of white cement in which the iron oxide
content is less than in the normal cement.
[0092] Referring to FIG. 4, a third possible embodiment of use, is
as described in the second one, but discharging the tire coal C to
the main burner 13. The main advantage of discharging the tire coal
C to the main burner 13 is that a higher percentage of primary fuel
substitution can be achieved mainly because the tire coal C is
burned in the main burner 13 after reaching the limit of energy
amount substituted at the pre-calcinator.
[0093] Referring to FIG. 5, a fourth possible embodiment of use
consists on using the residual air from the clinker cooler 14 which
is hotter than the atmosphere air, instead of using hot air from
the tertiary air duct 19. The volatiles V are discharged and burned
in the main burner 13 and the tire coal C is discharged to the
calcinator 10, achieving a higher percentage of primary fuel
substitution. In this case, the wire W is discharged outside of the
apparatus and of the rotary kiln 12, to containers or to a conveyor
belt (not shown). Therefore it is possible the application of the
recuperator R of the present invention at kilns without a
pre-calcinator.
[0094] Referring to FIG. 6, a fifth possible embodiment of use is
as described in the fourth one, but discharging the tire coal C to
the main burner 13. Therefore it is also possible the application
of the recuperator R of the present invention at kilns without a
pre-calcinator.
[0095] Referring again to FIG. 1, a sixth possible embodiment of
use is as described in the first one, but, instead of using whole
or shredded tires, alternative solid fuels having similar or the
same properties of the tires, are used, i.e., so that a residue
similar to coal be obtained.
[0096] Although it has been mentioned that the apparatus of the
present invention can be used at the cement industry, it can be
used at any kind of industry having industrial kilns. For example,
referring to FIG. 7, it can be used at a thermoelectrical plant or
any other industrial kiln, discharging the volatiles V and tire
coal C to the main burner 13, and discharging the wire W to outside
of the apparatus.
[0097] The method for fractionating alternative solid fuels,
especially whole tires, according to the present invention
comprises the steps of:
[0098] providing an apparatus including a gasifier wherein the
solid fuels will be partially burned and the volatiles will be
emitted;
[0099] feeding the alternative solid fuel to the gasifying zone of
the apparatus;
[0100] providing cool air to the gasifier from the atmosphere and
if possible hot air from a suitable source;
[0101] partially burning the alternative solid fuels into the
gasifying zone until most of the volatiles have been emitted, coal
with a minimum content of volatiles is obtained, and the non
combustible solids are separated;
[0102] discharging the volatiles from the gasifier to an industrial
kiln wherein the substitution of primary fuel will be made;
[0103] discharging the resultant coal and solids from the gasifier
by gravity or any other known means to an industrial kiln wherein
the substitution of primary fuel will be made or to a conveyor belt
or to a container for further use.
[0104] Although it was described that it is provided hot air to the
gasifier from a suitable source, it is suitable to make the
combustion with cool air only.
Tests Results
[0105] During several tests carried out with a co-current model
gasifier and with a countercurrent model gasifier the following
results were obtained:
1TABLE 1 Gasifier Obstructions And Percentage Of Coal Obtained Flow
Flow model nl/min Gasifier obstruction % discharged coal
Countercurrent 80 Negative 10.99% Countercurrent 80 Positive 11.62%
Countercurrent 80 Positive 22.23% Countercurrent 90 Negative 11.54%
Countercurrent 90 Positive 9.70% Countercurrent 90 Positive 9.71%
Co-current 80 Negative 23.43% Co-current 80 Negative 23.37%
Co-current 80 Positive 24.76% Co-current 90 Positive 26.33%
Co-current 90 Negative 25.26% Co-current 90 Negative 24.90%
[0106] The above table show the test in which obstruction occurred,
and the percentage of coal discharged (more discharged coal is
better).
2TABLE 2 Coal Distribution Discharged Flow model coal Sedimentation
coal Recuperated coal Countercurrent 10.99% 14.10% 25.09%
Countercurrent 11.62% 20.73% 32.35% Countercurrent 22.23% 16.30%
38.53% Countercurrent 11.54% 18.43% 29.97% Countercurrent 9.90%
15.48% 25.38% Countercurrent 9.71% 23.13% 32.83% Co-current 23.43%
2.06% 25.49% Co-current 23.37% 4.14% 27.51% Co-current 24.76% 3.76%
28.52% Co-current 26.33% 4.02% 30.35% Co-current 25.26% 3.04%
28.30% Co-current 24.90% 4.18% 29.08%
[0107] Table 2 shows the distribution of discharged, sedimentation
and total recuperated coal (more is better). In practice, the
recuperated coal would be only the discharged coal. The
sedimentation coal is the coal that the gas flow captured in the
sedimentation chamber. Table 2 shows that the countercurrent model
produces more sedimentation coal and takes a longer time to be
completely burned which is a disadvantage from the combustion
standpoint.
[0108] Finally it is to be understood that the apparatus and method
for fractionating alternative solid fuels of the present invention,
is not limited exclusively to the above described and illustrated
embodiments and that the persons having ordinary skill in the art
can, with the teaching provided by this invention, to make
modifications to the design and component distribution of the,
apparatus and method for fractionating alternative solid fuels of
the present invention, which will clearly be within the true
inventive concept and scope of the invention which is claimed in
the following claims.
* * * * *