U.S. patent application number 11/132901 was filed with the patent office on 2006-03-02 for waste treatment system for pta and pet manufacturing plants.
Invention is credited to Bruce Roger DeBruin, Robert Lin, Joseph Luther Parker, Timothy Alan Upshaw.
Application Number | 20060046217 11/132901 |
Document ID | / |
Family ID | 35943708 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060046217 |
Kind Code |
A1 |
Parker; Joseph Luther ; et
al. |
March 2, 2006 |
Waste treatment system for PTA and PET manufacturing plants
Abstract
The present invention provides a method for treating the wastes
of polyester-manufacturing processes. The method of the invention
comprises combining the fuel with a first waste byproduct stream to
form a combined fuel and first waste byproduct stream mixture that
is combusted in a furnace. The present invention also provides
certain useful variations of this method in which one or more of
the following steps are performed: a second waste byproduct stream
is introduced and treated in a regenerative thermal oxidizer, a
third waste byproduct stream is introduced and treated in a waste
water treatment plant, or a fourth waste byproduct stream is
introduced and treated in a fluid bed incinerator. The present
invention also provides an apparatus that executes the methods of
the invention.
Inventors: |
Parker; Joseph Luther;
(Kingsport, TN) ; Upshaw; Timothy Alan;
(Kingsport, TN) ; Lin; Robert; (Kingsport, TN)
; DeBruin; Bruce Roger; (Lexington, SC) |
Correspondence
Address: |
Steven A. Owen;Eastman Chemical Company
P.O. Box 511
Kingsport
TN
37662-5075
US
|
Family ID: |
35943708 |
Appl. No.: |
11/132901 |
Filed: |
May 19, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60606857 |
Sep 2, 2004 |
|
|
|
Current U.S.
Class: |
431/5 |
Current CPC
Class: |
F23G 2900/50001
20130101; F23G 7/068 20130101; F23G 5/006 20130101; F23G 5/30
20130101; F23G 2201/70 20130101; F23G 7/12 20130101 |
Class at
Publication: |
431/005 |
International
Class: |
F23D 14/00 20060101
F23D014/00 |
Claims
1. A method of treating waste in a polyester-manufacturing plant,
the polyester-manufacturing plant producing one or more waste
byproduct streams and having at least one heat source utilizing a
fuel as a combustion source, the method comprising: combining the
fuel with a first waste byproduct stream to form a combined fuel
and first waste byproduct mixture; and combusting the combined fuel
and first waste byproduct mixture in the at least one heat source;
and wherein the second waste byproduct stream is a liquid waste
stream which is vaporized before the second waste byproduct stream
is introduced into the regenerative thermal oxidizer.
2. The method of claim 1 wherein the at least one heat source is a
heat transfer medium furnace in which a liquid is circulated in a
coil that is exposed to an open flame and then further circulated
to heat exchange devices which transfer heat to polymer forming
reactors, the open flame being formed by the combustion of the fuel
and the one or more waste byproduct steams.
3. The method of claim 2 wherein the coil is heated to a
temperature of greater than about 300.degree. C.
4. The method of claim 2 wherein the fuel comprising a component
selected from the group consisting of natural gas, fuel oil, or
combinations thereof.
5. The method of claim 1 wherein the first waste byproduct stream
comprises an aqueous waste stream which includes an organic
compound.
6. The method of claim 5 wherein the combustible organic compound
is selected from the group consisting of ethylene glycol, acetic
acid, acid aldehydes, and combinations thereof.
7. The method of claim 1 wherein the polyester-manufacturing plant
is a PET or PTA forming plant.
8. The method of claim 1 wherein the first waste byproduct stream
comprises solid organic components, the solid organic components
being sufficiently combustible to be burned in the at least one
heat source.
9. The method of claim 1 wherein the polyester-manufacturing plant
comprises one or more reactors in which polycondensation is
utilized to form a polyester.
10. The method of claim 1 further comprising introducing a second
waste byproduct stream into a regenerative thermal oxidizer.
11. The method of claim 10 wherein the second waste byproduct
stream comprises a significant amount of non-condensble
compounds.
12. The method of claim 11 wherein the second waste byproduct
stream comprises an inert gas and a volatile organic compound.
13. The method of claim 12 wherein the volatile organic compound is
selected from the group consisting of acetic acid, methyl acetate,
and combinations thereof.
14. The method of claim 10 wherein the second waste byproduct
stream is a liquid waste stream which is vaporized before the
second waste byproduct stream is introduced into the regenerative
thermal oxidizer.
15. The method of claim 10 further comprising introducing a third
waste byproduct stream into a waste water treatment plant.
16. The method of claim 15 further comprising introducing a fourth
waste byproduct stream into a fluid bed incinerator.
17. The method of claim 16 wherein the fourth waste byproduct
stream comprises solid organic components, the solid organic
components being sufficiently combustible to be burned in the at
least one heat source.
18. The method of claim 17 wherein the fourth waste byproduct
stream comprise the take off gas from a distillation tower.
19. The method of claim 18 wherein the fourth waste byproduct
stream comprises an aqueous waste stream which includes a volatile
organic compound.
20. The method of claim 19 wherein the combustible organic compound
is selected from the group consisting of ethylene glycol, acetic
acid, acid aldehydes, and combinations thereof.
21. A method of treating waste in a polyester-manufacturing plant,
the polyester forming plant producing one or more waste byproduct
streams and having at least one heat source utilizing a fuel as a
combustion source, the method comprising: combining the fuel with a
first waste byproduct stream such that at least a portion of the
waste byproduct stream is at least partially combusted with the
fuel; introducing a second waste byproduct stream into a
regenerative thermal oxidizer; and introducing a third waste
byproduct stream into a fluid bed incinerator; and wherein the
second waste byproduct stream is a liquid waste stream which is
vaporized before the second waste byproduct stream is introduced
into the regenerative thermal oxidizer.
22. The method of claim 21 wherein the at least one heat source is
a heat transfer medium furnace in which a liquid is circulated in a
coil that is exposed to an open flame and then further circulated
to heat exchange devices which transfer heat to polymer forming
reactors, the open flame being formed by the combustion of the fuel
and the one or more waste byproduct steams.
23. The method of claim 21 wherein the second waste byproduct
stream comprises a significant amount of non-condensible
compounds.
24. The method of claim 21 wherein the second waste byproduct
stream comprises an inert gas and a volatile organic compound.
25. The method of claim 24 wherein the volatile organic compound is
selected from the group consisting of acetic acid, methyl acetate,
and combinations thereof.
26. The method of claim 21 wherein the second waste byproduct
stream is a liquid waste stream which is vaporized before the
second waste byproduct stream is introduced into the regenerative
thermal oxidizer.
27. The method of claim 26 wherein the third waste byproduct stream
comprises solid organic components, the solid organic components
being sufficiently combustible to be burned in the at least one
heat source.
28. The method of claim 26 wherein the third waste byproduct stream
comprise the take off gas from a distillation tower.
29. The method of claim 28 wherein the third waste byproduct stream
comprises an aqueous waste stream which includes a volatile organic
compound.
30. The method of claim 29 wherein the combustible organic compound
is selected from the group consisting of ethylene glycol, acetic
acid, acid aldehydes, and combinations thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 60/606,857, filed Sep. 2, 2004, the disclosure
of which is incorporated herein by this reference to the extent it
does not contradict statements made herein.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and apparatus for
treating the wastes produced in a polyester-manufacturing plant;
and in particular, the present invention relates to methods and
apparatus for treating the wastes from a PTA or PET plant in which
at least one heat source utilizes fuel as a combustion source.
BACKGROUND
[0003] Polyester is a widely used polymeric resin used in a number
of packaging and fiber based applications. Poly(ethylene
terephthalate) ("PET") or a modified PET is the polymer of choice
for making beverage and food containers such as plastic bottles and
jars used for carbonated beverages, water, juices, foods,
detergents, cosmetics, and other products. These containers are
manufactured by a process that typically comprises drying the PET
resin, injection molding a preform and, finally, stretch blow
molding the finished bottle. Despite the stringent matrix of
properties required for such uses, particularly for food packaging,
PET has become a commodity polymer. PET is also used in a number of
film and fiber applications. Commercial production of PET is energy
intensive, and therefore even relatively small improvements in
energy consumption are of considerable commercial value.
[0004] In the typical polyester forming polycondensation reaction,
a diol such as ethylene glycol is reacted with a dicarboxylic acid
or a dicarboxylic acid ester. In the production of PET,
terephthalic acid is usually slurried in ethylene glycol and heated
to produce a mixture of oligomers of a low degree of
polymerization. The reaction can be accelerated by the addition of
a suitable reaction catalyst. Since the product of these
condensation reaction tends to be reversible and in order to
increase the molecular weight of the polyesters, this reaction is
often carried out in a multi-chamber polycondensation reaction
system having several reaction chambers operating in series.
Typically, the diol and the dicarboxylic acid component are
introduced in the first reactor at a relatively high pressure.
After polymerizing at an elevated temperature the resulting polymer
is then transferred to the second reaction chamber which is
operated at a lower pressure than the first chamber. The polymer
continues to grow in this second chamber with volatile compounds
being removed. This process is repeated successively for each
reactor, each of which are operated at lower and lower pressures.
The result of this step wise condensation is the formation of
polyester with high molecular weight and higher inherent viscosity.
During this polycondensation process, various additives such as
colorants and UV inhibitors may be also added. Polycondensation
occurs at relatively high temperature, generally in the range of
280-300.degree. C., under vacuum with water and ethylene glycol
produced by the condensation being removed. The heat for the
polycondensation reactions is typically supplied by one or more
furnaces, such as heat transfer medium furnace ("HTM furnace").
Moreover, the during the polycondensation process, a number of
chemical waste byproducts are formed that need to be appropriately
treated in order to meet government regulations. Among the waste
products needing treatment in the typical PET process are acetic
acid, various acid aldehydes, and unreacted ethylene glycol.
[0005] In the typical process for making purified terephthalic acid
("PTA"), crude terephthalic acid is made by catalytic oxidation of
para-xylene followed by purification of the crude acid. Crude
terephthalic acid suitable for making polyesters is typically
produced by the oxidation of para-xylene in the presence of
catalyst and acetic acid solvent. Oxygen in the air functions as
the oxidant and converts the para-xylene in TPA. The reaction
mixture typically includes other components in addition to
para-xylene. Such additional components include a solvent, a
catalyst system, and a promoter. Suitable solvents include
monocarboxylic acids such as acetic acid. Catalyst systems that may
be used often include a heavy metal or mixture of heavy metals such
as cobalt and manganese in the form of acetate salts. Bromine in
the form of bromic acid is a commonly used promoter. For example,
U.S. Pat. No. 6,137,001 discloses a liquid-phase process in which a
benzene derivative or naphthalene derivative is oxidized with
oxygen to form a carboxylic acid. The reaction mixture in this
process typically includes a reaction catalyst comprising a heavy
metal component and a bromine source. U.S. Pat. No. 5,696,285
discloses a process in which the oxidation of para-xylene is
carried out using pure or nearly pure oxygen (great to or equal
than 75 vol. % oxygen). This process also improves reaction
efficiency by rapid dilution of the hydrocarbon feed stock. In a
somewhat similar process, U.S. Pat. No. 5,420,316 discloses a
process with very low amounts of aldehyde and ketone by-products in
which a carboxylic acid is made by the ozonization of an organic
compound having at least one olefinic bond followed by further
oxidation with molecular oxygen. After manufacturing of the crude
terephthalic acid, purification by hydrogenation or other methods
and crystallization can be done in order to obtain suitable
material for most PET applications. The main impurity
(4-carboxybenzaldehyde) is transformed to water-soluble para-toluic
acid during hydrogenation. It will also be appreciated that the
production of TPA and PTA both produce a number of byproducts that
need consideration for proper treatment and disposal.
[0006] Accordingly, there is a need for improved methods and
apparatus for treating the waste byproducts formed in the various
polyester-manufacturing processes in an energy efficient
manner.
SUMMARY OF THE INVENTION
[0007] The present invention overcomes one or more problems of the
prior art by providing in one embodiment a method of treating waste
in a polyester-manufacturing plant. The method of the invention
comprises combining the fuel with a first waste byproduct stream to
form a combined fuel and first waste byproduct stream mixture.
Next, the combined fuel and first waste byproduct mixture is
introduced into the first heat source and combusted. The present
invention also provides certain useful variations of this method in
which one or more of the following steps are performed: a second
waste byproduct stream is introduced and treated in a regenerative
thermal oxidizer, a third waste byproduct stream is introduced and
treated in a waste water treatment plant, or a fourth waste
byproduct stream is introduced and treated in a fluid bed
incinerator.
[0008] In another embodiment of the invention, a second method of
treating waste in a polyester-manufacturing plant is provided. The
method of this embodiment comprises combining the fuel with a first
waste byproduct stream to form a combined fuel and first waste
byproduct stream mixture. Next, the combined fuel and first waste
byproduct mixture is introduced into the first heat source and
combusted. The method further comprises introducing a second waste
byproduct stream into a regenerative thermal oxidizer and
introducing a third waste byproduct stream into a fluid bed
incinerator.
[0009] In yet another embodiment of the invention, an apparatus for
treating waste from a polyester-manufacturing plant that utilizes
the methods of the invention is provided. The apparatus of the
invention comprises a heat source that is used to both provide heat
to the one or more polymerization reactors and to combust the waste
and a first conduit that transfers a first waste stream from the
one or more polymerization reactors to the heat source. In certain
variations of the apparatus of the invention, the apparatus further
includes one or more of the following components: a regenerative
thermal oxidizer; a waste water treatment plant; and a fluid bed
incinerator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic illustrating embodiments of the
invention that are useful for treating the waste products from PET
and PTA manufacturing processes using the HTM furnace of the PET
process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0011] Reference will now be made in detail to presently preferred
compositions or embodiments and methods of the invention, which
constitute the best modes of practicing the invention presently
known to the inventor.
[0012] In an embodiment of the present invention, a method of
treating waste in a polyester-manufacturing plant is provided. With
reference to FIG. 1, a schematic of a polyester-manufacturing plant
in which PTA and PET are both formed is provided. The polyester
manufacturing plant 10 include PTA manufacturing component 12 and
PET manufacturing component 14. PTA manufacturing component 12
produces waste byproduct streams 16, 18, 20, 22. Waste byproduct
stream 16 is the off-gas waste from acetic acid/water separation
unit 24 which removes byproduct acetic acid from PTA manufacturing
line 26 while waste byproduct stream 18 comprises the aqueous
wastes from acetic acid/water separation unit 24. Waste byproduct
stream 20 contains solid wastes from PTA manufacturing line 26 and
waste stream 22 comprises other aqueous wastes coming directly from
PTA manufacturing line 26.
[0013] PET manufacturing component 14 produces waste byproduct
streams 28, 30. In PET manufacturing component 14, at least one
heat source 32 is used to provide heat for the condensation
reactions between the glycol and diacid that occur in at least one
condensation reactor 34. Ethylene glycol/water separation unit 36
removal waste from condensation reactor 34. Waste byproduct stream
28 includes the aqueous wastes from separation unit 36. Similarly,
waste byproduct stream 30 includes waste from condensation reactor
34. As will be shown below, the method of the present invention
advantageously utilizes a heat from heat source 32 to combust at
least one waste byproduct stream of waste byproduct streams 16, 18,
20, 22, 28, 30. The typical polyester-manufacturing process
produces a number of different waste byproducts that may be present
in the first waste byproduct stream. One type of waste byproduct
stream comprises an aqueous waste stream which includes one or more
combustible organic compounds. The type of organic compounds
present will depend on the specific polyester process. For example,
the manufacturing of PTA or PET typically produce ethylene glycol,
acetic acid, acid aldehydes, and combinations thereof. In addition
to the aqueous waste streams, the first waste byproduct stream may
also include solid organic components. These solid organic
components are also usually sufficiently combustible to be burned
in the at least one heat source.
[0014] Still referring to FIG. 1, the method of the invention
comprises combining fuel in conduit 40 with a first waste byproduct
stream to form a combined fuel and first waste byproduct stream
mixture. The first waste byproduct stream is combined with the fuel
via conduit 42. Such a mixing of the fuel and first waste byproduct
stream may occur within heat source 32 or prior to introduction of
the fuel into heat source 32. The combined fuel and first waste
byproduct mixture is introduced into heat source 32 and combusted.
Accordingly, at least a portion of the waste byproduct stream 30 is
at least partially combusted along with the fuel. Typically, heat
source 32 is a heat transfer medium furnace ("HTM furnace") in
which a liquid is circulated in a coil 38 that is exposed to an
open flame and then further circulated to heat exchange devices
which transfer heat to polymer forming reactors. As used in the
present embodiment, the open flame is formed by the combustion of
the fuel in conduit 40 and first waste byproduct stream 30.
Usually, coil 38 of the HTM furnace is heated to a temperature
greater than about 300.degree. C. A variety of fuels may be used in
heat source 32. Examples of suitable fuels include natural gas,
fuel oil, and combinations thereof.
[0015] In a first variation of the invention, the first waste
byproduct stream will combine one or more of waste byproduct
streams 16, 18, 20, 22, 28, 30. Preferably, the first waste
byproduct stream combines all of waste byproducts 16, 18, 20, 22,
28, 30.
[0016] In a second variation of the present embodiment, the method
of the present invention further comprises introducing a second
waste byproduct stream into a regenerative thermal oxidizer
("RTO"). RTOs are particularly suitable for removing (oxidizing)
byproduct streams that include a significant amount of vapor-phase
compounds. Often, such byproduct streams will include an inert gas
and one or more volatile organic compounds. Examples of volatile
organic compounds that are present in the waste streams of PTA and
PET plants are acetic acid, methyl acetate, and combinations
thereof. The second waste product stream may also be a liquid waste
stream which is vaporized before the second waste byproduct stream
is introduced into the regenerative thermal oxidizer. In accordance
with this variation, the second waste byproduct stream will include
the combination of one or more of waste byproduct streams 16, 18,
22, 28, 30. For example, the first waste byproduct stream that is
fed into heat source 32 includes wastes stream 20 while the second
waste byproduct stream includes waste streams 16, 18, 22, 28, 30
which are fed to RTO 50 via conduit 52. Alternatively, for example,
the first waste byproduct stream comprises waste byproduct streams
18, 22, 20, 28, 30 and the second waste byproduct stream includes
waste stream 16.
[0017] In a third variation of the present embodiment, the method
of the invention further comprises introducing a third waste
byproduct stream into a waste water treatment plant 60 via conduit
62. This second variation is performed either separately from or in
combination with the second variation set forth above. In
accordance with this variation, the third waste byproduct stream
will include the combination of one or more of waste streams 18,
22, 28, 30. For example, waste stream 20 is fed to heat source 32,
waste stream 16 is fed into RTO 50 via conduit 52, and waste
streams 18, 22, 28, 30 are fed to one of heat source 32, RTO 50, or
water treatment plant 60.
[0018] In a fourth variation of the present embodiment, the method
of the invention further comprises introducing a fourth waste
byproduct stream that is fed into a fluid bed incinerator 70 via
conduit 72. Again, this variation is performed separately from or
in combination with the first, second, and third variations. The
fourth waste byproduct stream comprises solid organic components,
the solid organic components being sufficiently combustible to be
burned in the at least one heat source. Moreover, the fourth waste
byproduct stream may be the take off gas from a distillation tower
from the various purification stages in a PET or PTA process.
Furthermore, this fourth waste byproduct stream may contain an
aqueous waste stream which includes a combustible organic compound.
As set forth above, examples of combustible organic compounds that
are present in a PET or PTA plant are ethylene glycol, acetic acid,
acid aldehydes, and combinations thereof. In accordance with this
variation, the fourth waste byproduct stream will comprise waste
stream 20. For example, waste stream 16 is fed into RTO 50, waste
stream 20 is feed to fluid bed incinerator 70, and waste streams
18, 22, 28, 30 are fed to heat source 32, RTO 50, or water
treatment plant 60.
[0019] In another embodiment of the invention, a second method of
treating waste in a polyester-manufacturing plant is provided. As
set forth above, polyester-manufacturing plants typically produce
one or more waste byproduct streams. Moreover, such plants will
typically have at least one heat source utilizing fuel as a
combustion source. The method of this embodiment comprises
combining the fuel with a first waste byproduct stream to form a
combined fuel and first waste byproduct stream mixture. Next, the
combined fuel and first waste byproduct mixture is introduced into
heat source 32 and combusted. The method further comprises
introducing a second waste byproduct stream into RTO 50 via conduit
52 and introducing a third waste byproduct stream into a fluid bed
incinerator 70 via conduit 72. The selection of the heat source is
the same as that set forth above for the first embodiment.
Moreover, the selection of the compositions of the first waste
byproduct stream, the second waste by byproduct stream, and the
third waste byproduct streams are also the same as those set forth
above. For example waste stream 16 is fed to RTO 50, waste stream
20 is feed to fluid bed incinerator 70, and waste streams 18, 22,
28, 30 are fed to heat source 32 or RTO 50.
[0020] In yet another embodiment of the invention, an apparatus for
treating waste from a polyester-manufacturing plant is provided.
With reference to FIG. 1, the apparatus of the invention include
heat source 32 that is used to both provide heat to at least one
condensation reactor 34 and to combust the waste. The apparatus
also includes a first conduit 42 that transfers a first waste
stream from the one or more polymerization reactors to the heat
source. The selection of a suitable heat source is the same as that
set forth above for the methods of the invention. Specifically, a
suitable heat source is a HTM furnace in which a liquid is
circulated in a coil that is exposed to an open flame and then
further circulated to heat exchange devices which transfer heat to
polymer forming reactors, the open flame being formed by the
combustion of the fuel and the one or more waste byproduct steams.
In a first variation of the apparatus of the invention, the
apparatus further includes RTO 50 with or without waste water
treatment plant 60 and/or fluid bed incinerator 70. In a second
variation, the apparatus of the invention includes heat source 32,
RTO 50, and fluid bed incinerator 70.
[0021] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *