U.S. patent application number 10/226051 was filed with the patent office on 2003-02-13 for method for recycling building materials.
Invention is credited to Bland, Brian W., Jones, David R..
Application Number | 20030029364 10/226051 |
Document ID | / |
Family ID | 24875307 |
Filed Date | 2003-02-13 |
United States Patent
Application |
20030029364 |
Kind Code |
A1 |
Bland, Brian W. ; et
al. |
February 13, 2003 |
Method for recycling building materials
Abstract
A method of recycling building materials is described, including
the steps of introducing the building material into a cement kiln
or a boiler, and combusting a combustible portion of the building
material as a fuel within the kiln or boiler. The noncombustible
portion of the building material is incorporated into a clinker
material within the kiln or used to reduce emissions form the
boiler.
Inventors: |
Bland, Brian W.; (Newark,
OH) ; Jones, David R.; (Tampa, FL) |
Correspondence
Address: |
OWENS CORNING
2790 COLUMBUS ROAD
GRANVILLE
OH
43023
US
|
Family ID: |
24875307 |
Appl. No.: |
10/226051 |
Filed: |
August 22, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10226051 |
Aug 22, 2002 |
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09715745 |
Nov 17, 2000 |
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6439139 |
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Current U.S.
Class: |
110/235 ;
110/341 |
Current CPC
Class: |
Y02P 40/10 20151101;
F23G 2900/7008 20130101; Y02P 40/145 20151101; Y02E 20/30 20130101;
F23G 7/00 20130101; Y02E 20/363 20130101; F23G 2206/201 20130101;
C04B 7/246 20130101; C04B 7/246 20130101; C04B 7/4438 20130101 |
Class at
Publication: |
110/235 ;
110/341 |
International
Class: |
F23D 014/00; F23B
007/00 |
Claims
What is claimed is:
1. A method of recycling building materials into a fuel and useful
residue material, comprising: introducing the building materials
into a combustion chamber; combusting a combustible portion of the
building materials as a fuel within the combustion chamber; and
using the noncombustible portion of the building materials as one
of a clinker material or an emissions reduction material.
2. A method according to claim 1, wherein an organic portion of the
building materials is combusted and an inorganic portion of the
building materials is incorporated into the clinker material or
used as an emissions reduction material.
3. A method according to claim 2, wherein the building materials
comprises a shingle, the recycling process further comprising the
steps of: combusting an asphalt material from a glass substrate of
the shingle; and incorporating said substrate into said clinker
material as a source of minerals for said clinker material or using
a filler in said asphalt as an emissions reduction material in a
boiler.
4. A method according to claim 3, wherein said method comprises
feeding said shingle into as a fuel to a fluidized bed boiler
having a fuel feed system and a lime feed system, and wherein the
amount of lime fed into the boiler is reduced based on the amount
of lime in the asphalt filler.
5. A method according to claim 3, wherein the asphalt is filled
with a limestone or dolomitic material and the limestone or
dolomitic material provides a source of lime to reduce the amount
of sulfur emissions from the boiler.
6. A method according to claim 5, wherein the shingle further
comprises surface granules, said granules providing a source of bed
material in said boiler.
7. A method according to claim 6, wherein said shingle comprises
scrap from the manufacture of roofing shingles.
8. A method according to claim 3, wherein said shingle is removed
from a building along with further building materials selected from
the group consisting of nails, wood, felt paper, ice shield, and
roofing accessories, and wherein each of said further building
materials provides fuel or bed materials for said boiler.
9. A method according to claim 2, wherein the building materials
comprise shingles.
10. A method according to claim 9, wherein the shingles comprise
asphalt and wherein the recycling process further comprising the
steps of combusting said asphalt and an organic substrate of the
shingle.
11. A method according to claim 10, wherein the shingle further
comprises an asphalt filler and wherein said lime comprises surface
granules, said granules providing a source of lime for said clinker
material or as an emissions reduction material in a boiler.
12. A method according to claim 11, further comprising the steps
of: combusting said asphalt from the glass substrate of the
shingle; and incorporating a noncombustible portion of the shingle
in the bed of the boiler.
13. A method according to claim 9, wherein the shingle comprises a
filled resinous material, the recycling process further comprising
the steps of: combusting said resin from a filler material of the
shingle; and using said filler as an emissions reduction material
in a boiler.
14. A method according to claim 1, further comprising: removing the
building materials from a building before introducing the building
materials into a cement kiln or a boiler.
15. A method according to claim 14, wherein the building materials
comprise siding.
16. A method of recycling building materials comprising a filled
asphalt into a cement material or combusting a portion of said
building materials in a boiler, comprising: introducing the asphalt
into a cement kiln or a boiler; combusting the asphalt as a fuel;
and incorporating the asphalt filler material into a clinker
material within the kiln or using said filler material as an
emissions reduction material in said boiler.
17. A method according to claim 16, wherein the building materials
comprises asphalt shingles, wherein said filler material of the
asphalt is incorporated as a source of lime into a clinker material
within the kiln or as an emissions reduction material in the
boiler.
18. A method of recycling asphalt shingles according to claim 17,
wherein the boiler comprises a fluidized bed boiler and the filler
material reduces emissions from the boiler.
19. A method of recycling asphalt shingles according to claim 18,
further comprising the step of incorporating a surfacing granule as
a bed material in said boiler.
20. A method according to claim 18, wherein the fluidized bed
boiler comprises a system for feeding an amount of lime into the
boiler, and wherein the amount of lime is reduced based on the
amount of lime in the shingles.
21. A method according to claim 18, wherein the fluidized bed
boiler comprises a system for feeding an amount of lime into the
boiler, and wherein the amount of lime is reduced based on the
amount of shingles fed into the boiler as fuel.
22. A method according to claim 18, wherein the fluidized bed
boiler comprises a system for feeding an amount of lime into the
boiler, and wherein the amount of lime fed from the lime feed
system is reduced by at least five percent due to the filler
material.
23. A method according to claim 18, wherein the boiler combusts an
amount of fuel, and wherein an amount of lime fed into the boiler
comprises at least five percent by weight of the fuel, and wherein
the shingles contribute at least ten percent of said lime.
24. A method according to claim 16, wherein the fluidized bed
boiler comprises a system for feeding an amount of lime into the
boiler, and wherein the amount of lime fed from the lime feed
system is reduced by at least five percent due to the filler
material.
25. A method according to claim 24, wherein the amount of lime fed
from the lime feed system is reduced by at least fifteen percent
due to the filler material.
26. A method according to claim 24, wherein the boiler combusts an
amount of fuel, and wherein the bed includes approximately twenty
percent lime by weight of the fuel, and wherein the asphalt
contributes at least one of said approximately twenty percent
lime.
27. A method according to claim 24, wherein the asphalt contributes
at least approximately three of said approximately twenty percent
lime.
28. A method according to claim 27, wherein said asphalt comprises
at least approximately ten percent of said fuel.
29. A method according to claim 27, wherein said asphalt comprises
asphalt shingles, and wherein said asphalt shingles comprise at
least approximately ten percent by weight of said fuel.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part to copending
application, U.S. Ser. No. 09/715,745, filed Nov. 17, 2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention is related generally to a method and
apparatus for recycling building materials in as a supplemental
fuel source and source of raw material(s).
[0004] 2. Prior Art
[0005] Cement is produced by heating raw materials, forming a
closely controlled chemical combination of calcium, silicon,
aluminum, iron and small amounts of other ingredients. Common among
the materials used in its manufacture are inorganic materials, such
as limestone, shells, and chalk or marl combined with shale, clay,
slate or blast furnace slag, silica sand, and iron ore. Lime and
silica typically make up about 85% of the mass. The raw materials
are heated in a cement kiln at high temperatures of typically
2600.degree. F. to 3000.degree. F. (1430.degree. C. to 1650.degree.
C.). The inorganic minerals are "digested" in the kiln through a
very complex set of chemical reactions, yielding oxides, and then
finally complex silicates, which comprise the clinker. At
2700.degree. F. (1480.degree. C.), this series of chemical
reactions cause the materials to fuse and create cement
clinker-grayish-black pellets, often the size of marbles. Clinker
is discharged red-hot from the lower end of the kiln in
marble-sized pieces, and is transferred to various types of coolers
to lower the clinker to handling temperatures. Cooled clinker is
combined with gypsum and ground into a fine gray powder. The
clinker is ground so fine that nearly all of it passes through a
No. 200 mesh (75 micron) sieve. This fine gray powder is (termed)
Portland cement.
[0006] The raw materials are placed in the high end and as the kiln
rotates the materials move slowly toward the lower end. Natural Gas
through Flame jets, and/or pulverized coal is feed in the lower end
of the kiln to heat the materials in the kiln. Utilizing counter
current flow, the kiln heat drives off, or calcines, the chemically
combined water and carbon dioxide from the raw materials and forms
new compounds (tricalcium silicate, dicalcium silicate, tricalcium
aluminate and tetracalcium aluminoferrite). Of the material that
goes into the feed end of the kiln, about 67% is discharged as
clinker.
[0007] As described in U.S. Pat. No. 5,454,333, pumpable and solid
hazardous wastes have been used a supplemental fuel to produce the
heat for heating the mixture. Such wastes are typically used
primarily for the heat value thereof.
[0008] U.S. Pat. No. 5,888,256, which is incorporated herein by
reference, describes a process for using various waste fuel
sources, analyzing the ash of each, and adjusting the raw material
inputs for the cement based on the ash composition. Such wastes are
previously known wastes used in such processes, such as sludge
waste and such.
[0009] U.S. Pat. No. 5,888,256, which is incorporated herein by
reference, describes a process for using various waste fuel
sources, analyzing the ash of each, and adjusting the raw material
inputs for the cement based on the ash composition. Such wastes are
previously known wastes used in such processes, such as industrial
waste sludge. The '256 patent requires a minimum of two waste
streams, and blending and grinding to achieve a maximum 1000-micron
particle size with a minimum BTU value and a maximum ash content.
Accordingly, the '256 patent restricts the type and form of wastes
which can be used.
[0010] U.S. Pat. No. 5,833,474 describes using waste materials from
electric arc furnaces to supplement the input materials for cement
to provide an inexpensive raw material, but not to recover fuel
value therefrom.
[0011] Likewise, during combustion of organic materials,
undesirable emissions typically occur, including SO.sub.x and
NO.sub.x. The level of such emissions may be affected by
controlling the combustion temperature and adding calcium carbonate
during combustion. A preferred means of accomplishing this includes
the use of a fluidized bed boiler ("FBB"). In such a boiler, a bed
is fluidized. This bed consists of fuel and lime added to the bed.
NO.sub.x is generally lower in a FBB due to the relatively low
temperature of the bed. As an added NO.sub.x control, secondary air
can be used as overfire air to further control NO.sub.x. The lime
within the bed captures the SO.sub.2 released from the burning fuel
and reacts to form calcium sulfate (gypsum).
[0012] Asphalt shingles have been used extensively as a roofing
material for the construction of buildings. In the process of
making shingles, an organic or glass mat is coated with asphalt
filled with limestone or dolomite, and inorganic granules are
imbedded in the filled asphalt. Waste product from such an
operation, or shingles removed from a house after their useful
life, are sent to a landfill, due to the variety of materials used
and the difficulty in separation of such materials. Often during
the removal of old shingles form a house, nails used in the
installation thereof, as well as rotten boards, tar paper, vents
and other such materials are removed and sent with the shingles to
the landfill. Furthermore, composite shingles have come into use in
the recent past, an example of which is the Owens Corning Mira
Vista.RTM. Shake, which comprises a filled polymeric shingle.
Similar to the asphalt shingle, such a composite shingle may be
recycled by combusting the polymeric material and using any filler
materials therefrom as a component of the cement. Furthermore,
other building materials such as siding materials, including
asphalt siding, cedar siding, cementious siding and such, may be
recycled in a similar manner.
[0013] It would be desirable to find an alternative disposal method
for scrap building materials from the manufacturing process and
building renovations, including asphalt shingles.
BRIEF SUMMARY OF THE INVENTION
[0014] According to the present invention, an improved recycling
process is described to recycle building materials. As such, the
disposal costs and landfill space for such materials are avoided.
Furthermore, the energy value of such materials is recovered, and
the inorganic constituents of the shingles or recycled building
materials are incorporated and become part of the minerals useful
in the manufacture of cement, and/or used as a material for
reducing the emission of undesirable emissions, reducing the cost
for these inputs in the manufacture of cement, or in the combustion
process of a fluidized bed boiler.
[0015] Accordingly, a method of recycling building materials is
described, including the steps of introducing the building material
into a cement kiln or fluidized bed, and combusting a combustible
portion of the building material as a fuel within the kiln or bed.
The noncombustible portion of the building material is incorporated
into a clinker material within the kiln, or utilized as a bed
material and/or to reduce the sulfur emissions from combustion.
BRIEF DESCRIPTION OF THE FIGURES
[0016] FIG. 1 is a schematic side view of a cement production
facility using the present invention.
[0017] FIG. 2 is a schematic side view of a fluidized bed boiler
using the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Cement is produced by preparing the necessary raw materials
in the necessary proportions and in the proper physical state of
fineness and intimate contact so that chemical reactions can take
place at the calcining and sintering temperatures in the kiln to
form the end product, typically referred to as clinker. In general,
the raw materials are crushed, passed through grinding, separation
and mixing apparatuses and then introduced to a kiln.
[0019] As noted in the Background section, to reduce energy and raw
material expense(s), numerous methods have been suggested to
introduce waste materials in the kiln during the manufacture of
Portland cement. U.S. Pat. No. 3,572,524 describes an apparatus for
charging sludges and other similar waste materials to the feed end
of a rotary incinerating kiln using an endless screw-conveyor. U.S.
Pat. No. 4,850,290 to Benoit et al., describes a method for
charging drums of solid hazardous waste directly into the central
portion of a rotary kiln or into the feed end housing of a kiln.
U.S. Pat. No. 5,454,333, describes a continuous feed method for
various waste materials, such as tires or drums of hazardous waste,
and describes various other methods for introducing solid hazardous
waste fuels into the rotary kilns. These patents are incorporated
herein by reference for such teachings.
[0020] FIG. 1 gives a schematic overall diagram of a cement
production apparatus 10. A kiln 20 includes an input end 12. Raw
materials 14 are input into the input end 12 in a known manner. As
taught in the prior art references, such input materials may enter
into a precalciner kiln system prior to introduction into the kiln
20. The kiln 20 may optionally include a supplemental fuel
introduction system 16, as described in the '256 patent. If so
equipped, fuel 18 is introduced as described therein. As noted
above, after the materials are calcinated, clinker is dispensed
from the exit end 22 of the kiln and handled in a known manner. The
material input system used with the present invention may include a
number of systems as described in the prior art and are therefore
not described herein in detail.
[0021] Scrap shingles, either the byproduct of the manufacturing
process for roofing shingles, or shingles which are removed from an
existing house, may be used as a fuel and raw material for the
production of Portland cement. Such shingles include asphalt
coating, which is useful as a fuel within the kiln. The asphalt
coating includes filler materials, such as limestone, which is an
input material for cement. The shingles further include a mat, made
from either organic material, which is further useful as fuel, or a
glass fiber mat. The glass fiber mat, when separated from the
asphalt and granules within the kiln, provides a source of silica,
which is another input material for the cement. The silica is then
combined with the other cement inputs within the kiln, and is
formed into the clinker. Normally, shingles include granules, which
provide further crushed and screened minerals, which provide
additional inputs for the concrete. Fiberglass asphalt shingles
typically comprise about 20% asphalt, 2% glass fiber, 65%
limestone, and the balance comprises various materials, mostly
minerals.
[0022] When a roof is stripped of shingles, additional building
materials, such as roofing underpayment (frequently asphalt coated
glass or organic mat), rubberized sheeting (ice guard), nails, wood
from the roof deck, roof vents, and other materials are also
removed and discarded with the shingles. The nails provide iron,
another input to the cement; while the felt may provide fuel and
glass; while the wood provides additional fuel for the kiln. As
such, scrap shingles provide several inputs to the cement
manufacturing process, as both fuel and raw materials, unlike other
previously proposed waste materials. As such, preferably the
mixture of inputs to the cement manufacturing process is determined
and modified in a manner as described in the '256 patent to create
the desired clinker formulation.
[0023] Preferably, the building materials, including the shingles,
may be introduced without grinding into the raw material hopper
(12), and the rotating kiln. Within the kiln, combustion of the
organics destroys the structure of the shingles and other building
materials, and the remaining inorganic materials are fully
incorporated into the clinker within the kiln. However, depending
on the feed system, it may be desirable to mill or grind large
input materials in some instances.
[0024] In a similar manner, natural shingles, such as cedar shakes,
may be disposed as a fuel source in a cement kiln. Furthermore,
composite shingles have come into use in the recent past, an
example of which is the Owens Coming Mira Vista.RTM. Shake, which
comprises a filled polymeric shingle. Similar to the asphalt
shingle, such a composite shingle may be recycled by combusting the
polymeric material and using any filler materials therefrom as a
component of the cement.
[0025] Furthermore, other building materials may be recycled in a
similar manner, using the fuel value of the materials in the cement
kiln, while using the noncombustible components as additional raw
materials for the cement. Examples include siding materials, such
as vinyl siding, asphalt siding, cedar siding, cementious siding
and such, may be recycled in a similar manner. Likewise, fiberglass
insulation may be recycled by placing such within the kiln, and
although mostly noncombustible, provides silica and other inorganic
constituents for the cement.
[0026] FIG. 2 schematically illustrates a fluidized bed boiler 210.
Such a boiler may comprise a bubbling bed, circulating fluidized
bed, or any known fluidized bed. In such a boiler, fuel is fed from
a feed source 212, and limestone is fed from a second source 214
into the bed 216 as an emissions reduction material. In such
fluidized bed combustion, fuel is introduced into the fluidized bed
216 and combusted. The fluidization is achieved by blowing
relatively low-velocity air into a medium such as sand. Lime is
injected into the bed 214. The present invention may be used in a
variety of fluidized beds, and therefore they are not described
herein in great detail. An exemplary description of a fluidized bed
boiler and its operation is included in Design Considerations of
B&W Internal Circulation CFB Boilers by Kavidass and Alexander,
presented to Power-Gen Americas '95, Dec. 5-7, 1995, which is
incorporated herein by reference. In the instant invention, the
building materials are fed into the fluidized bed, and the organic
portion of the building materials is combusted.
[0027] Typically a CFB utilizes fuels having between 3500 and 7000
British Thermal Units per pound (BTU/lb), and inject limestone in
an amount of about 20% by weight of the fuel. When asphalt shingles
are so combusted in a CFB, the fuel value comprises about 4200
British Thermal Units per pound (BTU/lb) (primarily from the
asphalt coating), and contain about 30-40 percent limestone
(calcium carbonate primarily from the asphalt coating filler), as
well as other inorganic materials such as the glass mat and colored
granules. In such an application, the shingles would preferably
comprise a portion of the fuel and a second fuel, preferably with
higher BTU value and lower lime percentage, is used to optimize
combustion and emissions. When asphalt shingles are combusted, the
asphalt from the shingles is combusted, the limestone is used
within the bed to control gases such as SOx and NOx, and the
granules and such are added to the bed as particulate bed material.
During operation of the bed while feeding these or other such
building materials, the amount of limestone and bed material is
adjusted based on the amount of each contained in the building
materials, as described above with respect to asphalt shingles.
Additionally, in a roof tear-off situation, wood and tar paper
and/or other building materials will contribute additional energy
value as well as inorganic bed materials, as is the case where
other building materials, such as siding, are combusted.
[0028] Preferably when building materials such as shingles are
combusted, a grinder, such as a Packer 2000 manufactured by Packer
Industries of Mableton, Ga., is used to reduce the size of the
shingles to pieces of preferably less than 3 inches in any
dimension. Preferably, the ground shingles are then fed into a
hammer mill with other combustion materials to reduce the size to
less than 1/2 inch in any dimension. In one trial at the Colmac
Resources, Inc. Piney Creek power plant in Clarion, Pa., scrap
shingles and manufacturing waste from Owens Coming's Medina, Ohio
shingle plant were ground and fed into a of waste coal at a ratio
of about 10% shingle scrap to total fuel. The ground shingles and
waste coal were hammered and fed into a CFB, and the flow rate of
the feed limestone dropped over 3% (from the typical 20%) to below
17% by weight of fuel due to the lime content of the shingles.
Accordingly, in this example, the shingles provided 15% of the
total lime required to maintain the emissions, and the mixed fuel
burned acceptably and emissions were within permissible limits. One
skilled in the art appreciates that the lime feed system may be
adjusted based on the amount and type of filler in the shingles (or
other building material) in combination with the percentage of
shingles to other fuels fed into the boiler, as well as the amount
of sulfur in the fuels, acceptable emissions limits, and other
control mechanisms on the boiler. Similarly, when other building
materials are combined with the fuel stream, the fuel value, lime
content, and filler content may used to adjust the stream of fuel,
lime and bed materials into the fluidized bed to an appropriate
ratio.
[0029] As noted above, fluidized bed combustion primarily consists
of the bubbling type and the circulating type. In the bubbling
type, because the velocity of the air is low, the medium particles
are not carried above the bed. In the circulating type, the
velocity of air is high, so the medium particles are carried out of
the combustor. The carried particles are captured by a cyclone
installed in the outlet of combustor.
[0030] In the bubbling type, combustion is generated within the
bed. In the circulating type, combustion is generated in the whole
combustor with intensive movement of particles. Typically secondary
air is added above the bed to minimize the excess air during
primary combustion so as to minimize the generation of pollutants.
In such a CFB, particles which leave the bed are continuously
captured by the cyclone and sent back to the bottom part of the
combustor to combust unburned particles and maintain the bed.
[0031] As described above, the input materials are fed into the
bed, the combustible portion, such as asphalt from roofing
shingles, is combusted, and the noncombustible portion remains. In
the present invention, the filler (lime) from the shingles is then
used within the bed as an input material to react with the sulfur
and reduce emissions. The remaining inorganic materials may become
part of the bed as well.
[0032] The embodiments were chosen and described to provide the
best illustration of the principles of the invention and its
practical application to thereby enable one of ordinary skill in
the art to utilize the invention in various embodiments and with
various modifications as are suited to the particular use
contemplated. Also such modifications and variations are within the
scope of the invention as determined by the appended claims when
interpreted in accordance with the breadth to which they are
fairly, legally and equitably entitled
* * * * *