U.S. patent application number 13/073421 was filed with the patent office on 2011-10-06 for utilization of waste heat using fiber sorbent system and method of using same.
This patent application is currently assigned to EXXONMOBIL RESEARCH AND ENGINEERING COMPANY. Invention is credited to Ian A. CODY, Bhupender S. MINHAS, Mohsen S. YEGANEH.
Application Number | 20110239692 13/073421 |
Document ID | / |
Family ID | 44625770 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110239692 |
Kind Code |
A1 |
MINHAS; Bhupender S. ; et
al. |
October 6, 2011 |
UTILIZATION OF WASTE HEAT USING FIBER SORBENT SYSTEM AND METHOD OF
USING SAME
Abstract
The disclosed subject matter relates to process modifications
and apparatus designs that are conducive towards minimizing
temperature swings (.DELTA.T) useful to yield operating pressures
that provide work and/or refrigeration (e.g., electricity and/or
refrigeration) in sorption systems. Such process modifications and
designs are particularly suited to make use of waste heat in
industrial process, (e.g., a chemical processing or petrochemical
refining operation) in which low grade heat source(s) are used to
drive the sorption system.
Inventors: |
MINHAS; Bhupender S.;
(Bridgewater, NJ) ; CODY; Ian A.; (Adelaide,
AU) ; YEGANEH; Mohsen S.; (Hillsborough, NJ) |
Assignee: |
EXXONMOBIL RESEARCH AND ENGINEERING
COMPANY
Annandale
VA
|
Family ID: |
44625770 |
Appl. No.: |
13/073421 |
Filed: |
March 28, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61319934 |
Apr 1, 2010 |
|
|
|
Current U.S.
Class: |
62/480 |
Current CPC
Class: |
B01J 20/18 20130101;
B01J 20/28023 20130101; B01J 20/3265 20130101; B01J 20/3272
20130101; Y02A 30/27 20180101; B01J 20/165 20130101; F25B 37/00
20130101; Y02A 30/276 20180101; F25B 29/006 20130101; B01J 20/3204
20130101; F25B 17/08 20130101; B01J 20/327 20130101; B01J 20/3293
20130101; B01J 20/2803 20130101 |
Class at
Publication: |
62/480 |
International
Class: |
F25B 17/08 20060101
F25B017/08 |
Claims
1. A fiber sorption system comprising: at least one vessel; a
working fluid; at least one thermal fluid; at least one hollow
fiber located within the at least one vessel, wherein the hollow
fiber including: (a) a sorbent material and binder material forming
an elongated body; (b) the elongated body having a hollow interior;
(c) the elongated body having an inner surface adjacent the hollow
interior and an outer surface; (d) one of the inner surface and the
outer surface having a coating layer formed thereon, wherein the
coating layer being impermeable to both the working fluid and the
thermal fluid.
2. The fiber sorption system according to claim 1, wherein the
coating layer is formed on the inner surface, wherein the thermal
fluid passing flowing the hollow interior.
3. The fiber sorption system according to claim 2, wherein the
coating layer is selected from the group consisting of poly(vinyl
chloride), poly(vinylidene chloride), poly(vinyl floride),
poly(vinylidene floride), ethylene vinyl alcohol copolymer, poly
vinyl alcohol, polyamides, polyethylene (preferably high density),
polypropylene (preferably high density), polyesters, polyimides,
polyacrylonitrile, polysulfone, polyurethane, combinations thereof
and derivatives thereof.
4. The fiber sorption system of claim 2, wherein the thermal fluid
includes a heating fluid and a cooling fluid.
5. The fiber sorption system of claim 4, wherein the heating fluid
comprises steam.
6. The fiber sorption system of claim 2, wherein the sorbent
material is a zeolite.
7. The fiber sorption system of claim 6, wherein the zeolite is
zeolite 13X.
8. The fiber sorption system of claim 1, wherein the working fluid
comprises carbon dioxide.
9. The fiber sorption system of claim 8, wherein the carbon dioxide
is from a process stream within a petrochemical or chemical
processing operation.
10. The fiber sorption system of claim 2, wherein the working fluid
is in fluid communication with the outer surface of the hollow
fiber.
11. The fiber sorption system according to claim 1, wherein the
coating layer is formed on the outer surface, wherein the working
fluid passing through the hollow interior such that it is capable
of being adsorbed and desorbed by the sorbent material in the
elongated body.
12. The fiber sorption system according to claim 11, wherein the
coating layer is selected from the group consisting of poly(vinyl
chloride), poly(vinylidene chloride), poly(vinyl floride),
poly(vinylidene floride), ethylene vinyl alcohol copolymer, poly
vinyl alcohol, polyamides, polyethylene (preferably high density),
polypropylene (preferably high density), polyesters, polyimides,
polyacrylonitrile, polysulfone, polyurethane, combinations thereof
and derivatives thereof.
13. The fiber sorption system of claim 11, wherein the thermal
fluid includes a heating fluid and a cooling fluid.
14. The fiber sorption system of claim 13, wherein the heating
fluid comprises steam.
15. The fiber sorption system of claim 11, wherein the sorbent
material is a zeolite.
16. The fiber sorption system of claim 15, wherein the zeolite is
zeolite 13X.
17. The fiber sorption system of claim 11, wherein the working
fluid comprises carbon dioxide.
18. The fiber sorption system of claim 17, wherein the carbon
dioxide is from a process stream within a petrochemical or chemical
processing operation.
19. The fiber sorption system of claim 11, wherein the working
fluid is in fluid communication with the inner surface of the
hollow fiber.
20. A fiber sorption system comprising: at least one vessel; a
working fluid; at least one thermal fluid; and at least one fiber
located within the at least one vessel, wherein each fiber
including a sorbent material and binder material forming an
elongated body having an outer surface, wherein the working fluid
flows past the outer surface and is capable of being adsorbed and
desorbed by the sorbent material.
21. The fiber sorption system according to claim 20, wherein the
thermal fluid flows past the outer surface and is not wetting the
fiber surface.
22. The fiber sorption system according to claim 20, further
comprising an outer coating on the outer surface, wherein the outer
coating being permeable to the working fluid such that working
fluid may pass through the outer coating for adsorption and
desorption by the sorbent material, wherein the outer coating being
impermeable to the thermal fluid, whereby the thermal fluid is
prevented from passing through the outer coating to the sorbent
material.
23. The fiber sorption system according to claim 22, wherein the
outer coating is formed from an organometallic compound.
24. A fiber sorption system comprising: at least one vessel; a
working fluid; a thermal fluid; at least one hollow fiber located
within the at least one vessel, wherein the hollow fiber including:
an inner coating defining a channel adapted to receive one of a
supply of the thermal fluid and the working fluid therein; an outer
coating defining a chamber between the outer coating and the inner
coating; and a sorbent material and a binder material contained
within the chamber, wherein one of the inner coating and the outer
coating is a generally impermeable membrane that is impermeable to
a thermal fluid, and wherein the other of the inner coating and the
outer coating is a generally permeable coating that is permeable to
a working fluid.
25. The fiber sorption system of claim 24, wherein the thermal
fluid includes a heating fluid and a cooling fluid.
26. The fiber sorption system of claim 25, wherein the heating
fluid comprises steam.
27. The fiber sorption system of claim 24, wherein the sorbent
material is a zeolite.
28. The fiber sorption system of claim 27, wherein the zeolite is
zeolite 13X.
29. The fiber sorption system of claim 24, wherein the working
fluid comprises carbon dioxide.
30. The fiber sorption system of claim 29, wherein the carbon
dioxide is from a process stream within a petrochemical or chemical
processing operation.
31. The fiber sorption system of claim 24, wherein the permeable
coating is selected from a cellulose fiber, a polysulfone, a
polyurethane and a polyimide.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application relates to and claims priority to U.S.
Provisional Application No. 61/319,934, entitled "Utilization of
Waste Heat Using Fiber Sorbent System and Method of Using Same",
filed on Apr. 1, 2010.
FIELD OF THE DISCLOSED SUBJECT MATTER
[0002] The disclosed subject matter relates to a fiber sorbent
system, and particularly a sorbent system for rapid heat transfer
capable of being heated and cooled rapidly.
BACKGROUND OF THE DISCLOSED SUBJECT MATTER
[0003] Chemical processing operations, including petroleum refining
and chemical processing operations, are energy intensive. It is
often necessary to conduct these operations at high temperatures
using high temperature heat sources including but not limited to
steam and other hot streams present in refining and petrochemical
processing facilities. After the steam and other hot streams have
performed their intended functions, there remains "waste" or
unutilized energy that can be further utilized. Refineries and
petrochemical facilities typically utilize only about 70% of the
input energy needed to conduct processing of crude oil to
products.
[0004] In an effort to increase efficiency, it is desirable to
recover and utilize the waste or unutilized heat. One method
described in U.S. Pat. No. 5,823,003 to Rosser et al. attempts to
make use of waste heat and apply such heat to an adsorbent material
in order to release an adsorbed gas at a higher pressure, which in
turn can be used in a refrigeration cycle that contains an
expansion valve. U.S. Pat. No. 5,823,003, the entirety of which is
incorporated herein, describes the use of a zeolite-water
combination for a sorption refrigeration system.
[0005] Current methods to obtain refrigeration and work from
sorbent materials in chemical process applications have
limitations. For example, the temperature swings (.DELTA.T)
provided by lower grade heat sources, such as waste heat, are less
than that which would be provided using primary heat sources. Such
limitations render the recovery of useful energy from waste heat
economically unsustainable, or impractical.
[0006] Accordingly, there remains a need to improve unutilized heat
recovery efforts (e.g., waste heat recovery) and render such
efforts more cost-effective by maximizing output from the
temperature swings (.DELTA.T) provided by lower grade sources.
There is a need to provide sorption systems with improved heat
transfer rate which are capable of being heated and cooled rapidly,
thus rendering sorption systems driven by lower grade heat sources
more economically sustainable.
SUMMARY OF THE DISCLOSED SUBJECT MATTER
[0007] The purpose and advantages of the disclosed subject matter
will be set forth in and apparent from the description that
follows, as well as will be learned by practice of the disclosed
subject matter. Additional advantages of the disclosed subject
matter will be realized and attained by the methods and systems
particularly pointed out in the written description and claims
hereof, as well as from the appended drawings.
[0008] To achieve these and other advantages and in accordance with
the purpose of the disclosed subject matter, as embodied and
broadly described, the disclosed subject matter includes a hollow
fiber sorbent system and particularly a sorption system capable of
being heated and cooled rapidly.
[0009] In accordance with one aspect of the present invention, a
fiber sorption system is provided. The system includes at least one
vessel, a working fluid, at least one thermal fluid and at least
one hollow fiber located within the at least one vessel. Each
hollow fiber includes a sorbent material and binder material that
together form an elongated body. The elongated body has a hollow
interior and an inner surface adjacent the hollow interior. One of
the inner surface and the outer surface has a coating layer formed
thereon. The coating layer being impermeable to both the working
fluid and the thermal fluid.
[0010] The coating layer may be formed from a material selected
from the group consisting of poly(vinyl chloride), poly(vinylidene
chloride), poly(vinyl floride), poly(vinylidene floride), ethylene
vinyl alcohol copolymer, poly vinyl alcohol, polyamides,
polyethylene (preferably high density), polypropylene (preferably
high density), polyesters, polyimides, polyacrylonitrile,
polysulfone, polyurethane, combinations thereof and derivatives
thereof.
[0011] In accordance with one aspect of the present invention, the
coating layer is formed on the inner surface. The thermal fluid
passes the hollow interior, but does not pass through the coating
layer to the sorbent material. The thermal fluid may include a
heating fluid and a cooling fluid. The working fluid may include
carbon dioxide. The carbon dioxide may be supplied from a process
stream within a petrochemical or chemical processing operation. The
working fluid is in fluid communication with the outer surface of
the hollow fiber.
[0012] In accordance with another aspect of the present invention,
the coating layer is formed on the outer surface. The working fluid
passing through the hollow interior such that it is capable of
being adsorbed and desorbed by the sorbent material in the
elongated body.
[0013] In accordance with another aspect of the present invention,
a fiber sorption system is disclosed comprising at least one
vessel, a working fluid, at least one thermal fluid and at least
one fiber located within the at least one vessel. Each fiber
includes a sorbent material and binder material forming an
elongated body having an outer surface. The working fluid flows
past the outer surface and is capable of being adsorbed and
desorbed by the sorbent material. The thermal fluid may flow past
the outer surface and is capable of transferring heat without
wetting the fiber surface. Thermal fluid contact angle with the
fiber surface is more than 90 degrees. The fiber may further
include an outer coating on the outer surface. The outer coating is
permeable to the working fluid such that working fluid may pass
through the outer coating for adsorption and desorption by the
sorbent material. The outer coating is impermeable to the thermal
fluid, whereby the thermal fluid is prevented from passing through
the outer coating to the sorbent material. The outer coating may be
formed from an organometallic compound.
[0014] In accordance with another aspect of the disclosed subject
matter, a fiber sorption system is disclosed comprising at least
one hollow fiber including an inner coating generally impermeable
to a thermal fluid (i.e. heating fluid or a cooling fluid) as well
as working fluid. The inner coating defines a channel adapted to
receive a supply of the thermal fluid (e.g., steam). The hollow
fiber further includes an outer surface that is permeable to a
working fluid. A chamber is defined by and between the outer
surface and the inner coating, with a sorbent material contained
within the chamber. The fiber sorption system further comprises a
supply of the working fluid (e.g., carbon dioxide) in fluid
communication with the outer surface of hollow fiber. Additionally,
the inner coating can be, for example, poly(vinyl chloride),
poly(vinylidene chloride), poly(vinyl floride), Poly(vinylidene
floride), Ethylene vinyl alcohol copolymer, poly vinyl alcohol,
polyamides, polyethylene (preferably high density), polypropylene
(preferably high density), polyesters, polyimides,
polyacrylonitrile, polysulfone, polyurethane, etc.--their
combinations or derivatives.
[0015] The disclosed subject matter also includes a method of
creating work from a pressurized working fluid that includes
providing a vessel containing a fiber sorption system as disclosed
herein, and introducing a supply of the working fluid to an
exterior surface of the outer coating; introducing the thermal
fluid (e.g., heating fluid) to the inner channel to obtain a
pressurized working fluid; and directing the pressurized working
fluid to a work component. The work component can be an expansion
valve to provide refrigeration, or a turboexpander to provide
electricity.
[0016] In accordance with another aspect of the disclosed subject
matter, a fiber sorption system is disclosed that includes at least
one hollow fiber including an inner surface that is permeable to a
working fluid, with the inner surface defining a channel adapted to
receive a supply of the working fluid (e.g., carbon dioxide). The
hollow fiber further includes an outer coating that is impermeable
to the thermal fluid and working fluid, wherein the outer coating
defines a chamber between the outer coating and the inner surface,
with a sorbent material contained within the chamber. The fiber
sorption system further includes a supply of the working fluid in
fluid communication with the inner surface. Additionally, the outer
coating can be, for example, poly(vinyl chloride), poly(vinylidene
chloride), poly(vinyl floride), Poly(vinylidene floride), Ethylene
vinyl alcohol copolymer, poly vinyl alcohol, polyamides,
polyethylene (preferably high density), polypropylene (preferably
high density), polyesters, polyimides, polyacrylonitrile,
polysulfone, polyurethane, etc.--their combinations or
derivatives.
[0017] The disclosed subject matter also includes a method of
creating a pressurized working fluid that includes providing a
vessel containing a fiber absorption system as disclosed herein,
and introducing a supply of the working fluid to the channel;
introducing the heating fluid to an exterior surface of the chamber
to obtain a pressurized working fluid; and directing the
pressurized working fluid to a work component. The work component
can be an expansion valve to provide refrigeration, or a
turboexpander to provide electricity.
[0018] In an exemplary embodiment, the channel and the chamber are
each circular in cross-section and concentric with each other
wherein the cross-section of the channel is about 50 microns to
about 400 microns in diameter. Additionally, the linear distance
from an interior surface of the outer membrane to an exterior
surface of the inner membrane is from about 50 to about 400
microns. The sorbent material is a zeolite, such as zeolite 13X,
and is about 10% to about 95% of the total weight of the
chamber.
[0019] The fiber sorption system disclosed herein is suitable for
use in applications in which the carbon dioxide is obtained from a
process stream within a petrochemical or chemical processing
operation, such as a combustion operation.
[0020] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and are intended to provide further explanation of the disclosed
subject matter claimed.
[0021] The accompanying drawings, which are incorporated in and
constitute part of this specification, are included to illustrate
and provide a further understanding of the method and system of the
disclosed subject matter. Together with the description, the
drawings serve to explain the principles of the disclosed subject
matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a schematic representation of a conventional
adsorption system.
[0023] FIG. 2 is a graphical illustration depicting the adsorptive
properties of a working fluid in accordance with the disclosed
subject matter.
[0024] FIG. 3 is a sectional view of an uncoated fiber for use in
the fiber sorbent system according to an embodiment of the present
invention.
[0025] FIG. 4 is a sectional view of a coated fiber for use in the
fiber sorbent system according to another embodiment of the present
invention.
[0026] FIG. 5 is a cross-sectional view of a hollow fiber for use
in the fiber sorbent system according to another embodiment of the
present invention.
[0027] FIG. 6 is a cross-sectional view of another hollow fiber for
use in the fiber sorbent system according to a yet another
embodiment of the present invention.
[0028] FIG. 7 is a cross-section view of yet another hollow fiber
for use in the fiber sorbent system according to the present
invention.
DETAILED DESCRIPTION OF THE DISCLOSED SUBJECT MATTER
[0029] The presently disclosed subject matter will now be described
in greater detail in connection with the Figures and the following
terms.
[0030] As used herein, the term "sorbent material" refers to a
material that reversibly binds to a working fluid. Sorbent
materials include, but are not limited to, adsorbents.
[0031] As used herein, the term "working fluid" refers to a liquid
or gas that can reversibly bind to the sorbent material, either in
a chemical or physical sense. When the working fluid is introduced
to an expansion valve, it can also be referred to as a
refrigerant.
[0032] As used herein, the term "driver device" refers to a
turbine, shaft or other mechanism driven by a working fluid to
generate electricity or work.
[0033] As used herein, the term "vessel" refers to a container
suitable for containing the fibers and a thermal fluid under
suitable conditions to permit sorption and desorption.
[0034] As used herein, the term "thermal fluid" refers to a liquid
or gas capable of introducing a temperature change to the sorbent
material. Thermal fluid can be a heating fluid or a cooling
fluid.
[0035] As used herein, the term "unutilized heat" or "unutilized
heat source" refers to the residual or remaining heat (e.g., steam)
following the processing operation after the heat sources has been
used for its primary purpose in the refining or petrochemical
processing operation. One example of an unutilized heat source is
"waste heat." For example, the unutilized heat or unutilized heat
source can be a heat source that is no longer used in refining
and/or petrochemical processing operation and would traditionally
be discarded. The unutilized heat can be provided as an unutilized
heat stream. For example, but not limitation, unutilized heat can
include steam that was employed in a heat exchanger used in
petroleum and petrochemical processing.
[0036] Reference will now be made to various aspects and
embodiments of the disclosed subject matter in view of the
definitions above. Reference to the methods will be made in
conjunction with, and understood from, the systems disclosed
herein.
[0037] For the purpose background and not admission of prior art,
an adsorption system 1000 is shown in FIG. 1. The system 1000 is
disclosed in U.S. patent application Ser. No. 12/603,243 entitled
"System Using Unutilized Heat For Cooling and/or Power Generation".
The disclosure of which is hereby incorporated in its entirety. An
adsorption bed (110) is provided, that contains tubes packed with
adsorbents (e.g., MOFs/ZIFs/Zeolites/Carbon). The adsorption bed is
adapted to receive either a feed of waste heat (120) or cold water
(130). During an adsorption stroke, the adsorption bed is provided
with a feed of cold water and the adsorbents adsorb working fluid
(e.g., CO.sub.2) at a lower temperature, T3, and lower pressure,
P2. The cold water supply is then valved off, and a feed of waste
heat is then fed to the adsorption bed to heat the adsorbent bed to
T1 (>T2) to release adsorbed working fluid. The heating
increases the pressure of the released working fluid P1 (>P2).
Thus the adsorbent acts as a compressor, and conventional devices,
e.g., pumps, are not required to drive the cycle.
[0038] The pressurized working fluid can be introduced to a
turboexpander (140) to generate electricity. Downstream of the
turboexpander, working fluid is now at a lower pressure, P2 and
lower temperature, T2. The thermodynamic conditions are such that
the working fluid is in an at least a partially condensed phase.
After exiting the turboexpander, the condensed working fluid is fed
to an evaporator (150) to chill a given process stream in the
refinery, which in turn increases the temperature of the working
fluid to T3. The working fluid is again introduced to adsorption
bed and the process is repeated.
[0039] The adsorption system shown in FIG. 1 is equipped with a
second adsorption bed (160), also adapted to receive a feed of
either waste heat (170) or cold water (180). Having two adsorption
beds in parallel allows one adsorption bed to be regenerated
(adsorption stroke) while the other adsorption bed is in desorption
mode. Other details regarding sorption systems can be found in U.S.
patent application Ser. No. 12/603,243, which is hereby
incorporated by reference in its entirety.
[0040] However, conventional designs have certain disadvantages.
For example, the indirect heating and cooling of the adsorbent
results in a slower heat transfer rate and longer temperature swing
cycle times. Consequently, this design requires bigger beds and/or
multiple beds which increases the cost of the adsorption system and
the infrastructure footprint. Additionally, such prior art systems
can be ineffective and/or cost prohibitive for use with low grade
waste heat, i.e., temperature below 300.degree. F.
[0041] One aspect of the disclosed subject matter is directed to a
replacement for the conventional adsorption beds. Particularly, a
fiber sorption system and method is provided for creating a
pressurized working fluid comprising at least one hollow fiber. The
hollow fiber can be constructed with an inner coating generally
impermeable to a thermal fluid and working fluid, and defining a
channel adapted to receive a supply of the thermal fluid. The
hollow fiber also includes an outer surface generally posing no
resistance to working fluid that defines a chamber between the
outer surface and the inner coating. A sorbent material is
contained within the chamber between the inner coating and outer
surface. In this configuration, a supply of working fluid is
introduced to an exterior surface of the fiber, and the thermal
fluid, e.g., heating fluid, is introduced to the channel to obtain
a pressurized working fluid from the sorbent material.
[0042] Alternatively, the disclosed subject matter provides a fiber
sorption system and method for creating a pressurized working fluid
wherein the hollow fiber is constructed with an inner surface
posing no resistance to working fluid permeation, and defining a
channel adapted to receive a supply of the working fluid. The
hollow fiber also includes an outer coating generally impermeable
to a thermal fluid (e.g., a heating fluid) and working fluid to
define a chamber between the outer coating and the inner surface. A
sorbent material is contained within the chamber between the inner
surface and outer coating. In this configuration, a supply of
working fluid is introduced to the inner channel of the fiber, and
the thermal fluid is introduced to the exterior surface of the
chamber to obtain a pressurized working fluid from the sorbent
material.
[0043] The system and methods of the disclosed subject matter
utilize the adsorptive properties of the selected sorbent, such as
MPFs/ZIFs/Zeolites, or the like, with respect to the working fluids
such as CO.sub.2, or the like. A schematic representation of these
adsorptive relationship is illustrated in FIG. 2. Particularly, an
increase in temperature reduces the amount of CO.sub.2 uptake.
Further, an increase in pressure reduces the CO.sub.2 uptake.
[0044] For purpose of illustration and not limitation, reference is
now made to several representative embodiments of the present
invention.
[0045] FIG. 3 discloses an uncoated fiber 10 for use in a sorbent
system in accordance with aspects of the present invention. The
fiber 10 includes an adsorbent 11 and a binder 12. In accordance
with an aspect of the present invention, the fiber 10 is made from
an adsorbent 11 and a binder 12 whose capacity and rate of
adsorption and desorption of working fluid is not affected by the
presence of thermal fluid. With such an arrangement, the fiber 10
is permeable to both the working fluid and the thermal fluid does
not wet the fiber surface. Suitable adsorbents are described in
greater detail below. The binder 12 or binding agent may be an
inorganic material (including but not limited to clay and silica
resin) or a polymeric material (including but not limited to
polyimide, polyamide, polyvinylalcohol, and cellulosic). Other
binder materials are considered to be well within the scope of the
present invention provided such binder materials do not adversely
impact the capacity and rate of adsorption and desorption of the
working fluid on the adsorbent 11.
[0046] In accordance with an aspect of the present invention
utilizing a fiber 10, the sorption system includes a plurality of
fibers 10 housed or otherwise contained within a vessel (e.g.,
adsorption beds 110 and 160). The working fluid and the thermal
fluid are capable of mixing within the vessel. While the present
invention is being described in connection with the system 1000
illustrated in FIG. 1, the present invention is not intended to be
so limited; rather, it is contemplated that the fibers 10 may be
utilized in any sorption system permitting the mixing of the
working fluid and the thermal fluid.
[0047] FIG. 4 discloses a coated fiber 20 for use in a sorbent
system in accordance with aspects of the present invention. The
fiber 20 includes an adsorbent 21, a binder 22 and an outer coating
23. The outer coating 23 is permeable to the working fluid, but is
impermeable to the thermal fluid. With such an arrangement, the
selection of the adsorbent 21 and the binder 22 is not limited to
those materials whose capacity and rate of adsorption and
desorption of working fluid is not affected by the presence of
thermal fluid.
[0048] The outer coating 23 is preferably an organometallic
compound. The metallo component of the organometallic compounds is
from Groups 4-15 based on the IUPAC format for the Periodic Table
having Groups 1-18, preferably Group 14, more preferably silicon
and tin, especially silicon. The organo components of the
organometallic compounds are hydrocarbyl groups having from 1 to 30
carbon atoms, preferably from 1 to 20 carbon atoms, more preferably
1-10 carbon atoms. The hydrocarbyl group may be aliphatic or
aromatic groups which aliphatic or aromatic groups may be
substituted with functional groups such as oxygen, halogen, hydroxy
and the like. Preferred hydrocarbyl groups include methyl, ethyl,
methoxy, ethoxy and phenyl. Preferred organometallic compounds
include alkoxysilanes, silanes, silazanes and phenyl siloxanes.
Especially preferred compounds include alkoxysilanes having from 1
to 4 alkoxy groups, especially tetraalkoxy compounds such as
tetraethoxy-silane, dialkoxysilanes having from 1 to 6 alkoxy
groups, especially hexamethyl-disiloxane.
[0049] The outer coating 23 of the organometallic material on the
fiber 20 should have a high water contact angle, higher than 90
degrees, preferably higher than 110 degrees. The outer coating 23
may not cover the entire outer surface of the fiber 20. In
accordance with the present invention, the outer coating 23 should
cover from greater than 25% of the outer surface of the fiber 20 to
100% of the surface, preferably from 50 to 100%, more preferably
from 80 to 100%. The amount of the outer surface covered is most
preferably 100% or as close to 100% as possible.
[0050] In accordance with an aspect of the present invention
utilizing a fiber 20, the sorption system includes a plurality of
fibers 20 housed or otherwise contained within a vessel (e.g.,
adsorption beds 110 and 160). The working fluid and the thermal
fluid are capable of mixing within the vessel. The outer coating 23
prevents the thermal fluid from passing through the fiber 20 into
the interior of the fiber 20 to the adsorbent 21 and the binder 22.
While the present invention is being described in connection with
the system 1000 illustrated in FIG. 1, the present invention is not
intended to be so limited; rather, it is contemplated that the
fibers 20 may be utilized in any sorption system permitting the
mixing of the working fluid and the thermal fluid, which prevents
the passage of the thermal fluid into the fiber 20.
[0051] FIG. 5 discloses a hollow fiber 30 for use in a sorbent
system in accordance with aspects of the present invention. The
hollow fiber 30 includes an adsorbent 31, a binder 32, and an inner
coating 33. The hollow fiber 30 contains a hollow interior 34,
which extends the length of the fiber 30. The hollow interior 34 is
configured to permit the thermal fluid to flow therein. The inner
coating 33 separates the hollow interior 34 from the adsorbent 31
and binder 32. The inner coating 33 is impermeable to both the
working fluid and the thermal fluid. With such an arrangement, the
selection of the adsorbent 31 and the binder 32 is not limited to
those materials whose capacity and rate of adsorption and
desorption of working fluid is not affected by the presence of
thermal fluid. The thermal fluid will not pass from the hollow
interior 34 into the interior of the fiber 30. The working fluid is
adsorbed into the adsorbent through the exterior of the fiber
30.
[0052] The inner coating 33 can be, for example, poly(vinyl
chloride), poly(vinylidene chloride), poly(vinyl floride),
poly(vinylidene floride), ethylene vinyl alcohol copolymer, poly
vinyl alcohol, polyamides, polyethylene (preferably high density),
polypropylene (preferably high density), polyesters, polyimides,
polyacrylonitrile, polysulfone, polyurethane, etc., their
combinations and derivatives thereof.
[0053] In accordance with the present invention utilizing a fiber
30, the sorption system includes a plurality of fibers 30 housed or
otherwise contained within a vessel (e.g., adsorption beds 110 and
160). The thermal fluid flows through the hollow interiors 34 of
the fibers 30. The thermal fluid provides the necessary heat
transfer to permit the adsorption and desorption of the working
fluid into the adsorbent 31. The working fluid is capable of
passing from the fiber 30 into the interior of the vessel without
mixing with the thermal fluid. While the present invention is being
described in connection with the system 1000 illustrated in FIG. 1,
the present invention is not intended to be so limited; rather, it
is contemplated that the fibers 30 may be utilized in any sorption
system, which prevents the mixing of the working fluid and the
thermal fluid.
[0054] FIG. 6 discloses a hollow fiber 40 for use in a sorbent
system in accordance with aspects of the present invention. The
hollow fiber 40 includes an adsorbent 41, a binder 42, and an outer
coating 43. The hollow fiber 40 contains a hollow interior 44,
which extends the length of the fiber 40. The hollow interior 44 is
configured to permit the working fluid to flow therein. The working
fluid can pass from the hollow interior 44 into the adsorbent 41
and binder 42. The outer coating 43 is impermeable to both the
working fluid and the thermal fluid. With such an arrangement, the
selection of the adsorbent 41 and the binder 42 is not limited to
those materials whose capacity and rate of adsorption and
desorption of working fluid is not affected by the presence of
thermal fluid. The thermal fluid will not pass into the fiber
40.
[0055] The outer coating 43 can be, for example, poly(vinyl
chloride), poly(vinylidene chloride), poly(vinyl floride),
poly(vinylidene floride), ethylene vinyl alcohol copolymer, poly
vinyl alcohol, polyamides, polyethylene (preferably high density),
polypropylene (preferably high density), polyesters, poly imides,
polyacrylonitril, polysulfone, polyurethane, etc.--their
combinations and derivatives thereof.
[0056] FIG. 7 depicts a representative embodiment of the fiber
sorption system in which at least one hollow fiber 50 is provided
with sorbents contained therein. Generally, however, the sorption
system includes a plurality of fibers housed or otherwise contained
within a vessel. In this non-limiting embodiment, the channel 51 is
adapted to receive steam (heating fluid) and water (cooling fluid).
The channel 51 is defined by an impermeable inner coating 52, such
as polyacrylonitrile (PAN). A chamber 53 is defined between the
inner coating 51 and an outer coating 54 and is packed with sorbent
particles 55, such as zeolite 13X or mesoporous silica with adhered
amines. The chamber also includes polymer support materials 56 to
assist in maintaining the structural integrity of the hollow
fiber.
[0057] The hollow fibers 56 can be formed in a tubular
configuration and include an inner coating 51 and an outer coating
54 defining a chamber 53 there between. In a preferred embodiment,
the chamber 53 extends along a length which is coextensive with the
inner and outer coating and contains the sorbent material (e.g.,
zeolite 13X). This maximizes the amount of sorbent material which
can be disposed within the chamber. Preferably, the sorbent
material is disposed within the chamber in an uniform concentration
or density along the length of the hollow fiber. The inner coating
defines a channel or bore within each hollow fiber. The channel
extends the entire length of the hollow fiber and is adapted to
receive a supply fluid for direct contact with the inner coating.
Depending on the embodiment of the hollow fiber sorption system, as
described further below, the fluid received within the channel can
be either a working fluid, or a thermal fluid (e.g.,
heating/cooling fluid).
[0058] In one embodiment, the inner coating is generally
impermeable to a thermal fluid, and the outer coating, which is
generally permeable to a working fluid, defines a chamber between
the outer coating and the inner coating. In this configuration, a
supply of working fluid is introduced to an exterior surface of the
outer coating, and the thermal fluid (e.g., heating fluid) is
introduced within the channel to obtain a pressurized working fluid
from the sorbent material. Alternatively, the inner coating can be
generally permeable to a working fluid, and the outer coating can
be generally impermeable to a thermal fluid. In this configuration,
a supply of working fluid is introduced within the inner channel of
the fiber, and the thermal fluid (e.g., heating fluid) is
introduced to the exterior surface of the chamber to obtain a
pressurized working fluid from the sorbent material.
[0059] In an exemplary embodiment, the hollow fibers of
approximately 100 micron inner diameter, and 100 micron chamber
thickness. This configuration allows for dense packing of sorbents
within the sorption bed. Fibers of this scale are advantageous in
that the temperature of the sorption bed can be altered from hot to
cold within seconds. Further, such a frequency of temperature swing
allows for the size and footprint of the sorption system to be
minimized. The channel and the chamber of each hollow fiber
preferably circular in cross-section and oriented with a concentric
configuration. For example, the channel is substantially circular
and from about 50 microns to about 400 microns in diameter.
Additionally, the linear chamber thickness can be from about 50 to
about 400 microns.
[0060] In accordance with another aspect of the disclosed subject
matter, a plurality of fibers can be arranged in a bundle similar
to a shell and tube heat exchanger. The plurality of fibers can be
aligned in a generally parallel arrangement. Alternatively, the
plurality of fibers can be oriented at an angle with respect to
each other. The fibers can be disposed with portions of adjacent
fibers in contact with each other, or provided with a uniform space
disposed therebetween over the entire length of the fibers. In an
exemplary embodiment, with the outer surface posing no resistance
to a working fluid and an inner coating impermeable to a thermal
and working fluids, the shell side can be in communication with a
working fluid (e.g., CO.sub.2) and the bore side can be in
communication with heating medium (e.g., steam) or cooling
medium.
[0061] In a preferred embodiment, waste heat (e.g., low grade waste
heat) is used as a heating fluid to drive the sorption system. In
some applications of the disclosed subject matter, the heating is
provided by waste heat from a chemical processing or petrochemical
refining operation. In one embodiment, the unutilized heat ranges
from about 343K to about 573K, or more preferably from about 363K
to about 523K.
[0062] While the working fluid is, for purposes of simplicity,
largely described in the context of CO.sub.2, other working fluids
can be employed. In one embodiment, the working fluid is a gas and
is selected from carbon dioxide, methane, ethane, propane, butane,
ammonia, chlorofluorocarbons (e.g., Freon.TM.), other refrigerants,
or other suitable fluids. Similarly, the sorbent material is
largely described in the context of zeolite 13X, but is not limited
thereto. In one embodiment, the sorbent material is selected from
zeolites, silicagel, carbon, activated carbon, metal organic
frameworks (MOFs), and zeolitic imidazolate frameworks (ZIFs). In
one embodiment the working fluid is carbon dioxide and/or the
sorbent material is a zeolite. In one embodiment the working fluid
is carbon dioxide and the zeolite is a zeolite X, preferably a
zeolite 13X.
Sorbent Materials
[0063] As noted above, and as used in this application, the term
"sorbent material" refers to a material that reversibly binds the
working fluid, in a chemical or physical sense. Sorbent materials
include adsorbents.
[0064] Sorbent materials that can be used in embodiments of the
disclosed subject matter include, but are not limited to,
metal-organic framework-based (MOF-based) sorbents, zeolitic
imidazole framework (ZIF) sorbent materials, zeolites and
carbon.
[0065] MOF-based sorbents include, but are not limited to,
MOF-based sorbents with a plurality of metal, metal oxide, metal
cluster or metal oxide cluster building units. As disclosed in
International Published Application No. WO 2007/111738, which is
hereby incorporated by reference in its entirety, the metal can be
selected from the transition metals in the periodic table, and
beryllium. Exemplary metals include zinc (Zn), cadmium (Cd),
mercury (Hg), and beryllium (Be). The metal building units can be
linked by organic compounds to form a porous structure, where the
organic compounds for linking the adjacent metal building units can
include 1,3,5-benzenetribenzoate (BTB); 1,4-benzenedicarboxylate
(BDC); cyclobutyl 1,4-benzenedicarboxylate (CB BDC); 2-amino 1,4
benzenedicarboxylate (H.sub.2N BDC); tetrahydropyrene
2,7-dicarboxylate (HPDC); terphenyl dicarboxylate (TPDC); 2,6
naphthalene dicarboxylate (2,6-NDC); pyrene 2,7-dicarboxylate
(PDC); biphenyl dicarboxylate (BDC); or any dicarboxylate having
phenyl compounds.
[0066] Specific materials MOF-based sorbent materials include:
MOF-177, a material having a general formula of
Zn.sub.4O(1,3,5-benzenetribenzoate).sub.2; MOF-5, also known as
IRMOF-I, a material having a general formula of
Zn.sub.4O(1,4-benzenedicarboxylate).sub.3; IRMOF-6, a material
having a general formula of Zn.sub.4O(cyclobutyl
1,4-benzenedicarboxylate); IRMOF-3, a material having a general
formula of Zn.sub.4O(2-amino 1,4 benzenedicarboxylate).sub.3; and
IRMOF-11, a material having a general formula of
Zn.sub.4O(terphenyl dicarboxylate).sub.3, or
Zn.sub.4O(tetrahydropyrene 2,7-dicarboxylate).sub.3; and IRMOF-8, a
material having a general formula of Zn.sub.4O(2,6 naphthalene
dicarboxylate).sub.3.
[0067] Exemplary zeolitic imidazole framework (ZIF) sorbent
materials include, but are not limited to, ZIF-68, ZIF-60, ZIF-70,
ZIF-95, ZIF-100 developed at the University of California at Los
Angeles and generally discussed in Nature 453, 207-211 (8 May
2008), hereby incorporated by reference in its entirety.
[0068] Zeolite adsorbent materials include, but are not limited to,
aluminosilicates that are represented by the formula
M.sub.2/nO.Al.sub.2O.sub.3.ySiO.sub.2.wH.sub.2O, where y is 2 or
greater, M is the charge balancing cation, such as sodium,
potassium, magnesium and calcium, N is the cation valence, and w
represents the moles of water contained in the zeolitic voids.
Examples of zeolites that can be included in the methods and
systems of the present application include natural and synthetic
zeolites.
[0069] Natural zeolites include, but are not limited to, chabazite
(CAS Registry No. 12251-32-0; typical formula
Ca.sub.2[(AlO.sub.2).sub.4(SiO.sub.2).sub.8.]3H.sub.2O), mordenite
(CAS Registry No. 12173-98-7; typical formula
Na.sub.8[(AlO.sub.2).sub.8(SiO.sub.2).sub.40].24H.sub.2O), erionite
(CAS Registry No. 12150-42-8; typical formula (Ca, Mg, Na.sub.2,
K.sub.2).sub.4.5.[(AlO.sub.2).sub.9(SiO.sub.2).sub.27].27H.sub.2O),
faujasite (CAS Registry No. 12173-28-3, typical formula (Ca, Mg,
Na.sub.2,
K.sub.2).sub.29.5[(AlO.sub.2).sub.59(SiO.sub.2).sub.133].235H.s-
ub.2O), clinoptilolite (CAS Registry No. 12321-85-6, typical
formula Na.sub.6[(AlO.sub.2).sub.6(SiO.sub.2).sub.30].24H.sub.2O)
and phillipsite (typical formula: (0.5Ca, Na,
K).sub.3[(AlO.sub.2).sub.3(SiO.sub.2).sub.5].6H.sub.2O).
[0070] Synthetic zeolites include, but are not limited to, zeolite
A (typical formula:
Na.sub.12[(AlO.sub.2).sub.12(SiO.sub.2).sub.12].27H.sub.2O),
zeolite X (CAS Registry No. 68989-23-1; typical formula:
Na.sub.86[AlO.sub.2).sub.86(SiO.sub.2).sub.106].264H.sub.2O),
zeolite Y (typical formula:
Na.sub.56[(AlO.sub.2).sub.56(SiO.sub.2).sub.136].250H.sub.2O),
zeolite L (typical formula:
K.sub.9[(AlO.sub.2).sub.9(SiO.sub.2).sub.27].22H.sub.2O), zeolite
omega (typical formula:
Na.sub.6.8TMA.sub.1.6[AlO.sub.2).sub.8(SiO.sub.2).sub.28].21H.sub.2O,
where TMA is tetramethylammonium) and ZSM-5 (typical formula: (Na,
TPA).sub.3[(AlO.sub.2).sub.3(SiO.sub.2).sub.93].16H.sub.2O, where
TPA is tetrapropylammonium).
[0071] Zeolites that can be used in the embodiments of the present
application also include the zeolites disclosed in the Encyclopedia
of Chemical Technology by Kirk-Othmer, Volume 16, Fourth Edition,
under the heading "Molecular Sieves," which is hereby incorporated
by reference in its entirety.
[0072] Synthetic zeolite sorbent materials are commercially
available, such as under the Sylosiv.RTM. brand from W.R. Grace and
Co. (Columbia, Md.) and from Chengdu Beyond Chemical (Sichuan, P.
R. China). For example, Sylosiv.RTM. A10 is one commercially
available zeolite 13X product.
Uses of the Fiber Sorbent Systems of the Present Application
[0073] The adsorbent systems of the present application can be used
in various applications provided the setting allows for the
presence of a vessel that contains a sorbent material, a supply of
working fluid, a heat supply and means to effectively direct the
desorbed working fluid to an expansion device to provide
refrigeration or a driver device to provide electricity or work.
For example, the desorbed gas may be directed to a Joule-Thompson
expansion valve, to provide refrigeration. Alternatively, the
desorbed working fluid can be directed to a turbine to provide
electricity or to a shaft to provide work. The sorption systems
described herein may be used to provide chilling, power and
chilling in combination with power.
[0074] Possible applications for sorption systems of the present
application include residential (for generating air conditioning in
the summer and a heat pump in the winter), vehicular (where the
on-board air conditioning utilizes exhaust heat) and industrial
(refining and chemical plants).
[0075] In a preferred embodiment of the present application, the
adsorbent system is used within a chemical or petrochemical
refining plant, and the desorbed working fluid is used to provide
refrigeration to aid in other process areas, particularly areas
that rely on temperature differences to separate components of a
mixture. For example, the refrigeration can be used to recover
liquefied petroleum gas (LPG, C3+) from flue gases going up a
stack, or the refrigeration can be used to operate condensers to
improve the effectiveness of vacuum distillation columns,
particularly in the summer months.
[0076] By proper selection of the adsorbent and working fluid, the
sorbent system can make effective use of lower grade heat than
previously provided by sorption systems in the prior art. For
example, in one embodiment of the present application, the heat
supply is "unutilized heat" which has a temperature of from about
70.degree. C. to about 300.degree. C., more preferably from about
90.degree. C. to about 250.degree. C. In accordance with the
present invention, it is contemplated that the adsorbent and
working fluid may be selected utilizing the pressure index
disclosed in U.S. patent application Ser. No. 12/603,243 entitled
"System Using Unutilized Heat For Cooling and/or Power Generation".
The disclosure of which is hereby incorporated in its entirety. By
proper selection of thermal fluid and coating material the negative
effect of capillary action should be kept minimal. By using
appropriate surfactant and additives in thermal fluid/coating
material to reduce interfacial tension between the thermal fluid
and the coating, e.g., for water, detergent and the like and for
triethylene glycol, stearic acid and the like.
[0077] This representative embodiment is provided for exemplary
purposes; neither the application nor the invention is limited to
the specific embodiments discussed above, or elsewhere in the
application.
[0078] The disclosed subject matter is not to be limited in scope
by the specific embodiments described herein. Indeed, various
modifications of the invention in addition to those described
herein will become apparent to those skilled in the art from the
foregoing description and the accompanying Figures. Such
modifications are intended to fall within the scope of the appended
claims.
[0079] It is further to be understood that all values are
approximate, and are provided for description.
[0080] Patents, patent applications, publications, product
descriptions, and protocols are cited throughout this application,
the disclosures of each of which is incorporated herein by
reference in its entirety for all purposes.
* * * * *