U.S. patent application number 12/034325 was filed with the patent office on 2008-06-12 for reforming and hydrogen purification system.
This patent application is currently assigned to Genesis Fueltech, Inc.. Invention is credited to Peter David DeVries.
Application Number | 20080134577 12/034325 |
Document ID | / |
Family ID | 32042113 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080134577 |
Kind Code |
A1 |
DeVries; Peter David |
June 12, 2008 |
Reforming and Hydrogen Purification System
Abstract
A reforming and hydrogen purification system operating with
minimal pressure drop for producing free hydrogen from different
hydrogen rich fuels includes a hydrogen reforming catalyst bed in a
vessel in communication with a core unit containing a hydrogen
permeable selective membrane. The vessel is located within an
insulated enclosure which forms an air inlet passageway and an
exhaust passageway on opposite sides of the vessel. Air and
raffinate pass through a burner within the air inlet passageway,
providing a heated flue gas to heat the catalyst to the reaction
temperature needed to generate free hydrogen from the feedstock.
The burner flue gas flows laterally over and along the length of
the bed between the input and output ends of the bed. Hydrogen is
recovered from the core for use by a hydrogen-consuming device such
as a fuel cell. The remaining unrecovered hydrogen in the reformed
gases is contained in raffinate and is used to supply process heat
via the burner. The exhaust flue gas and the inlet air supply pass
through a recuperator in which the inlet air is heated from the hot
exhaust gas. The feedstock input line is also coupled to the
raffinate line and the hydrogen recovery line to preheat the
feedstock prior to entry into the catalyst bed.
Inventors: |
DeVries; Peter David;
(Spokane, WA) |
Correspondence
Address: |
Andrus, Sceales, Starke & Sawall, LLP
Suite1100, 100 East Wisconsin Avenue
Milwaukee
WI
53202
US
|
Assignee: |
Genesis Fueltech, Inc.
Spokane
WA
|
Family ID: |
32042113 |
Appl. No.: |
12/034325 |
Filed: |
February 20, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10263949 |
Oct 3, 2002 |
7341609 |
|
|
12034325 |
|
|
|
|
Current U.S.
Class: |
48/61 |
Current CPC
Class: |
C01B 2203/041 20130101;
C01B 2203/0405 20130101; C01B 3/501 20130101; C01B 2203/0811
20130101; Y02P 20/129 20151101; C01B 3/384 20130101; C01B 2203/0233
20130101 |
Class at
Publication: |
48/61 |
International
Class: |
B01J 7/00 20060101
B01J007/00 |
Claims
1-50. (canceled)
51. A counterflow heat recuperating system for heating of an inlet
air supply in a reformer for producing hydrogen having an air inlet
chamber and adjacent exhaust flue gas outlet chamber separated by a
common wall, said recuperating system comprising a plurality of
heat transmitting plates formed of thermally conductive material,
each of said plates transversely mounted on said vertical wall and
extending across said air inlet chamber and said exhaust flue gas
outlet chamber and including a plurality of distributed openings to
permit essentially free inlet air flow and exhaust flue gas flow
through said plates, and sealing means between said plates and said
common wall to prevent mixing exhaust flue gas and inlet air gas
streams, whereby said plates facilitate the flow of heat from the
exhaust flue gas stream to the inlet air supply.
52. The system of claim 51 where said sealing means comprises a
thermally insulating sealing member placed between each of said
plates, and where the sealing member is of sufficient width to
substantially prevent mixing of the inlet air and exhaust flue
gas.
53. The system of claim 52 wherein each of said heat transmitting
plates is located in a plane perpendicular to the flow of said
inlet air supply and said exhaust flue gas.
54-55. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] The present invention is directed to a steam reformer for
producing purified hydrogen including purified hydrogen for fuel
cells.
[0002] Purified hydrogen is an important commodity in
semiconductor, metallurgical, and chemical processing. It is also
highly useful as a source of fuel for fuel cells, which can produce
electrical power from hydrogen. There are a variety of means for
producing purified hydrogen. Hydrogen can be liberated from
hydrogen-containing compounds such as alcohol by reforming with
steam at elevated temperatures over a catalyst bed. Since this
reaction is endothermic, the heat can be supplied from an external
burner, or the heat can be supplied in-situ by mixing some oxygen
and partially burning some of the fuel. The former process is
generally called steam reforming; when air or oxygen is mixed with
the fuel to supply heat the process is referred to as autothermal
or partial oxidation reforming. Once the reforming process has been
completed, substantial percentages of carbon monoxide will exist in
the reformed gas; this carbon monoxide may be further reacted in a
water-gas shift catalyst bed to form hydrogen and carbon dioxide.
This lowers the percentage of carbon monoxide in the reformed
gas.
[0003] To create high purity hydrogen from the reformed gas
mixture, means can be employed to separate the hydrogen, e.g. via a
selective membrane. The high purity hydrogen can then be used in an
industrial process, in a fuel cell for power generation or other
applications requiring purified hydrogen. In some cases, hydrogen
purification is not used; the reformed gas is sent to a fuel cell
after a selective oxidation step to further reduce carbon monoxide
levels. In the latter case, the reformer will generally require
dewpoint control, careful attention to prevent high carbon monoxide
levels, and integration means with the fuel cell to receive the
spent gas after much of the hydrogen has been exhausted.
[0004] The technology for hydrogen purification is well known, such
as disclosed in U.S. Pat. No. 5,861,137 entitled Steam Reformer
With Internal Hydrogen Purification issued Jan. 19, 1999. The above
patent discloses a hydrogen purification system and discusses the
prior art and the state of the prior art. The need for a practical
reformer, requiring a cost effective design is clear. The patent
discloses a method and system for partially extracting of a portion
of purified hydrogen from an appropriate fuel feedstock of hydrogen
containing fuel and using the discharged raffinate, with a
significant amount of hydrogen therein, as the fuel for operating
the burner.
[0005] In addition to a significant number of patents, a
substantial volume of other publications are available describing
various systems and aspects of hydrogen purification including
systems based on steam reforming. Nevertheless, there is continuing
demand for an improved hydrogen purification system which is cost
effective both initially and during its operating life, as well as
readily adapted for efficient and cost effective servicing. There
is a particular demand for a reformer with a low pressure drop in
the burner air system.
SUMMARY OF THE INVENTION
[0006] The present invention is particularly directed to a hydrogen
purification reformer which may be constructed as a compact unit
with efficient heating of the reformer from a burner. The burner
gas has a minimal pressure drop in the system which results in a
low power and low cost air supply for processing of the hydrogen
rich fuel.
[0007] The novel reformer system of the present invention includes
a catalyst unit or bed which is constructed and arranged along the
path of a feedstock between a feedstock input and a spaced
feedstock output. The catalyst is operable upon heating to
establish an endothermic reaction on the feedstock to produce
hydrogen. The catalyst may be of any operative material, in any
available form, such as a self supporting mass, a granular mass or
combination thereof. If a granular mass is used, a confining
enclosure supports the mass with a construction allowing release of
the hydrogen therefrom for subsequent collection via a hydrogen
permeable membrane.
[0008] In accordance with a particular feature of this invention, a
burner unit has a flue gas output stream communicating essentially
directly from the burner unit to the catalyst unit and having a
length substantially on the order of the length of the catalyst
unit, i.e. typically the spacing between the catalyst unit's outlet
and inlet. The flue gas stream thus passes laterally over
substantially the entire length of the catalyst resulting in
minimal air pressure drop in the system.
[0009] A hydrogen collector is located adjacent the catalyst unit
to collect the purified hydrogen, or may alternatively be located
downstream in the same or in a separate pressure vessel. In
accordance with current practice, the hydrogen collector may
include one or more hydrogen selective permeable membrane units
located along the path of the hydrogen liberated from the catalyst
bed to collect the hydrogen.
[0010] The preferred construction particularly provides for the
efficient functioning of the catalyst and the heating of the
catalyst, the feedstock and the air supply, as well as permitting
use of a relatively low pressure air supply, yielding higher energy
efficiency.
[0011] This construction thus establishes improved heating of the
catalyst to produce the free hydrogen and the extraction thereof
from a catalyst unit. This system further permits optimizing the
heating pattern of the stream over the length of the bed for the
internal processing of the feedstock, as hereinafter described.
[0012] In a preferred construction, a pressure vessel contains a
closed hydrogen selective permeable membrane core unit surrounded
by a catalyst bed or unit. A gas fired heating unit has a flue gas
output which is aligned with the pressure vessel and particularly
the catalyst unit. The heating unit creates a flue gas stream
related to the length and cross section of the catalyst unit. The
flue gas stream passes laterally over the catalyst unit to heat the
catalyst unit throughout the length thereof. The catalyst unit may
be heated uniformly or may be heated to a desired thermal
gradient.
[0013] The hydrogen rich feedstock passing through the heated
catalyst unit is reformed, producing hydrogen. A substantial
portion of this hydrogen subsequently passes through the hydrogen
selective permeable membrane core unit, and the remaining hydrogen
and other gases, hereinafter referred to as raffinate, exits the
pressure vessel, passes through a pressure control device such as a
back pressure regulator, and is subsequently is used to supply heat
for the reforming process via the gas fired heating unit.
[0014] The heating unit is preferably a catalytic burner which is
preferably fueled by the raffinate exiting the pressure vessel. The
burner may be a separate burner or constructed as an integrated
part of the pressure vessel. In either construction, the raffinate
is mixed with air, travels through the burner, and passes a heated
stream of flue gas directly from the burner over the pressure
vessel.
[0015] In either construction, the pressure vessel includes an
outer shell or wall which is formed of a heat conductive material.
A plurality of heat conductive fins are intimately affixed to the
outer wall throughout the vessel, through which the heated burner
flue gas passes to thoroughly heat the reforming catalyst bed
contained within the pressure vessel. The pressure vessel is
located between and defines an inlet burner flue gas passageway and
an outlet burner flue gas passageway.
[0016] In a preferred construction, the feedstock is preheated
through recovery of heat from at least one of the purified
hydrogen, the raffinate, and the burner flue gas, and preferably
from all three sources. Even if the feedstock is fully preheated to
the desired reaction temperature, the endothermic reaction within
the catalyst generally requires an additional supply of heat such
as from the burner flue gas in order to maintain a sufficient
temperature for the desired reforming reactions to occur.
[0017] The pressure vessel is also preferably formed with a
hydrogen collection system including one or more collection
structures. Each collection structure includes an inner membrane
core of a porous material with a metallic hydrogen permeable
selective membrane affixed to the core that forms a hydrogen
selective core-membrane unit. The metallic hydrogen selective
membrane may, for example, be a palladium or a palladium-copper
alloy coating, the latter which may be fabricated with plating and
annealing techniques familiar to those skilled in the art. In
addition, each core-membrane unit is separated and spaced from the
catalyst unit, particularly where a granular catalyst is used, to
prevent abrading contact of the thin membrane with the catalyst
material. For this purpose and particularly where a granular
catalyst is used, a guard layer may be placed between the catalyst
and the membrane, where the guard is porous or contains apertures
for communicating the reformed gases to the hydrogen selective
permeable membrane.
[0018] The pressure vessel is further formed in the preferred
embodiment with an outer closed end and an opposite open end, which
may be closed by a releasable cover or header unit. The input and
output lines are secured to the cover. The lines include a
feedstock line to input the feedstock into the catalyst bed, a
raffinate output line to receive the raffinate from the catalyst
unit and a purified hydrogen output line for transmitting the
purified hydrogen from the core-membrane unit.
[0019] The pressure vessel is typically formed of a metallic alloy.
A plurality of spaced fins, which are also good conductors of heat,
are firmly affixed to and extend from the pressure vessel. However,
in smaller embodiments where the surface-area-to-volume ratio is
favorable, the fins may not be necessary for heat transfer into the
catalyst area, and the pressure vessel fins may then be eliminated
from the preferred embodiment, with the vessel still defining the
air and heating gas passageway and the exit or exhaust
passageway.
[0020] The heating system preferably includes a controlled
distribution of a stream of the burner fluid or flue gas over the
catalyst unit to produce an optimal reforming of feedstock. This
requires a maximum heat input at the inlet or entrance of the
feedstock into the unit with a progressive patterned reduction or
gradient over the length of the unit to the outlet, since a higher
proportion of the endothermic reaction occurs nearest the entrance
point (the inlet end) into the catalyst.
[0021] In accordance with a further aspect of the invention, the
burner flue gases, the heated raffinate and the collected hydrogen,
all of which contain significant levels of heat are used to heat
the cold input air to the burner and to preheat the hydrogen rich
feedstock prior to passing of the feedstock through the reforming
catalyst unit.
[0022] In a preferred construction, separate conduits carry the
raffinate and the purified hydrogen as they exit the pressure
vessel. The conduits each include at least in part a metal or other
heat transfer material which are coupled and preferably bonded to
each other and to a corresponding third metal conduit carrying the
feedstock to the catalytic unit, in counterflow fashion. The
several conduits are preferably coupled to each other by a high
heat transfer bonding, as by welding, brazing or the like, to
promote heating of the cold feedstock. Other forms of coupling the
conduits may be used.
[0023] In addition, in one preferred construction, the flue gas
from a catalytic burner unit downstream of the catalyst bed is
coupled to an extended length of the input feedstock line, as by
locating a coiled length thereof within the outlet passageway
carrying the hot exhaust flue gas. This construction can be used to
preheat the feedstock with the flue gas exhaust, which is
particularly advantageous when using a catalytic burner.
[0024] In accordance with a further preferred construction, a
burner air inlet chamber for supplying air to the burner and an
exhaust chamber for discharging of the flue gas from the catalytic
unit are located in closely-spaced side-by-side orientation. A heat
recuperator includes a transfer assembly extended between the two
chambers to thereby capture the heat in the burner flue gas and
transmit the heat to the burner inlet air, preferably in a
counterflow fashion, prior to exhausting of the flue gas from the
system. This construction can be used to preheat the burner inlet
air with the flue gas exhaust.
[0025] A preferred structure of the heat transfer assembly includes
a series of relatively thin heat conductive and apertured plates
which extend between and across the two chambers. The plates are
separated by thin thermally insulating separators between the
adjacent chambers to prevent the burner flue gas from passing into
the air inlet chamber or passageway. These thin separators may also
serve to thermally isolate the apertured plates from one
another.
[0026] The reformer apparatus is further preferably constructed by
orienting of the components in a linear, parallel orientation along
a linear axis. The maximum output is thereby related to the
proportional linear length of the related components, with the
catalytic burner area, catalyst volume, and heat transfer surface
areas generally remaining constant per unit length of the
device.
[0027] Thus, the location and structure of the burner, and several
heat recuperating systems have a linear orientation related to the
pressure vessel. The capacity of the reforming system is then
directly related to the linear length of the components in the
final assembly resulting in efficient and ready scaling of hydrogen
generation.
[0028] Various monitors may be and preferably are coupled to the
fluids within the system to control the operation of the
reformer.
[0029] Various other objects, features and advantages of the
invention will be made apparent from the following description
taken together with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The drawings disclose a preferred embodiment of the
invention connected to a hydrogen fuel cell.
[0031] In the drawings:
[0032] FIG. 1 is a schematic illustration of a steam reformer unit
for producing purified hydrogen coupled to a fuel cell;
[0033] FIG. 2 is a pictorial view of a hydrogen purifying unit;
[0034] FIG. 2a is a view of the hydrogen purifying unit of FIG. 2
with a partial removal of the outer walls;
[0035] FIG. 3 is a rear perspective view of FIG. 2a;
[0036] FIG. 4 is a rear perspective view of a hydrogen reformer
unit shown in FIG. 2 with a reformer vessel unit removed;
[0037] FIG. 5 is a perspective view the vessel unit shown in FIG. 4
for reforming of purified hydrogen;
[0038] FIG. 6 is an exploded cross sectional view of the vessel
unit shown in FIG. 5.
[0039] FIG. 7 is a cross section of the vessel unit shown in FIGS.
5 and 6;
[0040] FIG. 7a is an enlarged fragmentary sectional view of parts
shown in FIGS. 6 and 7 to illustrate a detail of a sealing
unit;
[0041] FIG. 8 is a right front perspective view of the hydrogen
reformer unit shown in FIG. 4 with the outer enclosure partially
removed;
[0042] FIG. 8a is a sectional view of a brazed connection of system
fluid lines to preheat the feedstock fuel prior to introduction
into the pressure vessel;
[0043] FIG. 9 is a left front perspective view of the reformer unit
shown in FIGS. 4 and 8, with the outer enclosure partially
removed;
[0044] FIG. 9a is a left rear perspective view of the reformer unit
shown in FIG. 9;
[0045] FIG. 9b is a cross-sectional view illustrating a parallel
heat processing input passageway and an exhaust output passageway
with the inter-related system components;
[0046] FIG. 10 is an end view of a heat transfer and recuperative
unit shown in FIGS. 8 and 9-9b for preheating the air supply to the
burner in the instance where the seal between the plates is only
formed in one axis;
[0047] FIG. 11 is an enlarged view of a heat transfer plate of FIG.
10 with an improved plate separating structure;
[0048] FIG. 12 is a graphical illustration of the heat input to the
catalytic bed and the resulting free hydrogen created; and
[0049] FIG. 13 is a view of a structure for supplying raffinate to
the burner to provide a dispersed flue gas to the finned pressure
vessel.
DESCRIPTION OF ILLUSTRATED EMBODIMENT
[0050] FIG. 1 is a simplified illustration of a system for
generating purified hydrogen from a hydrogen rich fuel source 1 for
consumption by device 14, which may, for example, be a fuel cell
used for supplying electrical power to a load. The illustrated
embodiment of FIG. 1 includes a unique hydrogen purifier 18 within
a suitable support such as outer housing 36, in combination with
the associated components.
[0051] The system of FIG. 1 includes a steam reformer having a
reformer pressure vessel unit 19 which is operable to process
fuel/water feedstock from a source 1. Although a common pump for
the fuel and water is illustrated for the case where the fuel and
water are miscible as a pre-mixed feedstock, it is understood that
more than one pump may be used for the fuel and water,
respectively, along with any needed flow and pressure monitoring
means, with the fuel and water streams meeting together prior to
arriving at the catalyst filled chamber 7. The pressure vessel unit
19 contains an inner hydrogen purifier core unit 18. The pressure
vessel unit 19 is larger than the unit 18 and forms the
catalyst-filled chamber 7.
[0052] The fuel from source 1 is shown as a mixture of fuel and
water and constitutes a feedstock which is pulled through line 17
to filter 2, and pumped by a pump 3 via a line 4 to the counterflow
heat exchanger 9. After receiving heat at heat exchanger 9 the
feedstock then receives more heat in heat exchanger 5, finally
arriving at pressure vessel 19 by means of line 6 into pressure
vessel inlet connection 60. The feedstock thus is fed into catalyst
filled chamber 7, which is heated, as hereinafter described, and
the fuel/water feedstock reacts to produce free hydrogen. Unit 18
is an elongate member which contains a special hydrogen selective
permeable membrane, as hereinafter described, which passes the
hydrogen contained in the reformed gases into the interior of unit
18, wherein the purified hydrogen is subsequently transferred to
line 11 by means of hydrogen outlet 62. While generally illustrated
as a tubular member the shape of unit 18 is not constricted to any
particular form, and can assume any form suitable for the
application. Hydrogen purified by unit 18 and passing through line
11 transmits heat to the feedstock in heat exchanger 9 prior to
passing through hydrogen output pressure regulator 12. Once the
hydrogen pressure has been regulated by regulator 12 the hydrogen
may then pass through solenoid valve 13 to consuming device 14.
Since consuming device 14 may consist of a fuel cell with a
required periodic bleed, a return line from consuming device 14 is
included, with passage through bleed solenoid valve 15 and check
valve 16, where the bleed hydrogen is injected into line 83.
[0053] The volume and activity of catalyst 7 and the heating
thereof is such that the processed fuel is nearly completely
steam-reformed by the time it is withdrawn through line 8.
[0054] The remaining fuel and reaction by-products, including
unliberated hydrogen, hereinafter referred to as raffinate, is
withdrawn from catalyst-filled chamber 7 by a line 8. The raffinate
then transmits heat to the incoming feedstock in heat exchanger 9,
after which it passes through feedstock back pressure regulator 10.
The raffinate depressurizes upon passing through regulator 10 and
travels though line 83 to burner distributor 21.
[0055] A catalytic burner 75 is mounted within outer housing 36 to
receive raffinate from distributor 21 mixed with burner air. The
raffinate is discharged into the air flow via pores or holes in
distributor 21, such as more clearly shown in FIG. 13 for a
dual-distributor mechanism. The air and raffinate are mixed at the
input to burner 75 which creates a hot flue gas stream 75a which
passes into the adjacent chamber and functions as described above
to heat the catalyst filled chamber 7.
[0056] The system shown in FIG. 1, provides particular features for
improving the efficiency and functioning of the reforming process
for the generation and purification of hydrogen. In particular, the
system provides various heat recovery from the heated fluids in the
lines at heat exchanger 9 and the heated flue gases 78a which flow
downstream of heat exchanger 5.
[0057] As shown in FIG. 1, the portions of lines 4, 8 and 11 are
coupled to each other by a counterflow heat exchange unit 9 which
transfers heat from the reformed gases back to the incoming
feedstock in counterflow fashion. This improves efficiency and also
serves to cool the gas prior to arrival at hydrogen output
regulator 12 and feedstock pressure regulator 10, protecting the
devices from thermal damage. In addition, as also shown in FIG. 1,
the line 4 is shown with a coiled heat exchanger section 5 which is
in contact with the burner flue gas 79. Heat exchanger 5 is
configured to raise the feedstock to the desired operating
temperature for the catalyst in catalyst-filled chamber 7.
Depending on the capacity of the reformer, heat exchanger 5 may
include several turns of finned tubing to facilitate heat transfer
from flue gas 79, or it may consist of an unfinned tube with one or
more parallel turns.
[0058] Additionally, a heat transfer assembly 30 is located
spanning the exhaust chamber 91 and the burner air inlet chamber 90
downstream of fan 20 and fan filter 20a. A backup fan 20b, as
illustrated in FIG. 2a, may also be used in series with the main
fan 20. The hot flue gas 78a entering assembly 30 raises the
temperature of the assembly 30 on the flue gas side which transmits
the heat into the cool portion of the assembly 30 on the air inlet
in a counterflow fashion. More specifically, the assembly 30 is
specially constructed to prevent the transfer of fluids in the
respective chambers into the other chamber, as more fully described
in a preferred construction of the system of FIG. 1, as shown in
FIGS. 2-12, by the use of thermally insulating sealing gasket 97.
Insulating gaskets 97 furthermore allow the perforated or expanded
metal plates 96 of assembly 30 to operate at different temperatures
such that counterflow exchange may be improved.
[0059] While the arrangement of heat exchangers regulators, valves,
and the like illustrated in FIG. 1 are specifically shown in a
preferred orientation, various arrangements of parts may be
employed to achieve similar results within the framework of the
invention, and may be arranged as needed by those skilled in the
art.
[0060] Referring to FIGS. 2-4, a compact hydrogen source unit 33
includes an outer enclosure wall 34 (partially shown in FIGS. 2a-4)
within which an air supply section 35 is formed across the front
wall, and connected to a hydrogen generating unit enclosed in
enclosure 36. A control section 37 is located to the one side of
the air supply section 35 and the hydrogen generator unit in
enclosure 36. Section 37 contains various parts previously
described in FIG. 1 such as the pressure regulation and solenoid
valves.
[0061] The air supply section 35 includes a housing with an air
filter 20a within which an air supply fan 20 is located with a
backup fan 20b downstream of fan 20. As illustrated in FIG. 2a the
backup fan 20b is an axial type, and the main fan 20 is of a blower
type. Fan 20 pulls air through filter 20a and blows it into a
housing surrounding backup fan 20b. An air passageway tube 38
connects the output end of backup fan 20b to the hydrogen generator
unit in enclosure 36. The outer face of the housing 35a is covered
by filter 20a and an outer apertured face cover 38b.
[0062] The hydrogen generator unit in enclosure 36 is mounted
behind the air supply section 35 and is surrounded by perimeter
insulation 39 resting on a rigid thermally insulating base support
platform 39a. The insulation surrounding the high temperature parts
contained in enclosure 36 permits the efficient operation of the
reformer. Specifically this is done by placing the metallic
fastening means to enclosure 36 at the lowest temperature portion
of enclosure 36. This includes the air passageway tube 38, and the
top of unit 33 in FIG. 2, to which enclosure 36 is fastened. This
permits structural attachment of enclosure 36 to the rest of device
33 while minimizing thermal losses. The input of the air to the
generating unit in enclosure 36 is via the air passageway tube 38.
It should be noted that the perimeter wall insulation 39 is only
partially shown for clarity of illustrations and understanding of
the processing of the air and heating fuel system of the preferred
system.
[0063] Referring to FIGS. 4-8, the pressure vessel unit 19 of FIG.
1 is shown in a preferred finned construction and identified
hereinafter as pressure vessel 40. The pressure vessel 40 includes
an outer shell or container 42 within which an inner purifier core
unit 41 which is centrally located and secured. In the preferred
embodiment, a separate cup-shape guard member 51 is secured between
the outer shell or container 42 and the purifier core unit 41. The
guard member 51 is spaced from the container 42 and forms a
catalyst chamber 7 and is also spaced from the core unit 41 to
prevent abutting engagement of a granular catalyst 50 in chamber 7
with the core unit 41.
[0064] In particular, the container 42 includes an outer tubular
wall 45, open at both ends prior to assembly. The outer end is
closed by a flat end wall 46 welded with weld 47a (47a denoting all
welds in FIGS. 6 and 7) to the tube 45 and spaced from the inner
ends of the cup-shaped guard member 51 and purifier core unit 41.
The opposite or inner end of the tube 45 is closed by a header unit
46a including a flange member 47 secured to the open end of the
tube 45, as by a weldment 47a. Header unit 46a is bolted with bolts
53 in a sealed connection using copper seal ring 52a to the flange
member 47. The guard member 51 and the purifier core unit 41 are
secured to the header 46a to form a removable unit relative to the
flange 47 and the outer shell 45 or container 42. Cover 64 is also
attached to the flange 46a via bolts 53.
[0065] The cup-shaped guard member 51 is formed of suitable
perforated metal or other suitable material to confine the catalyst
50 and to permit free passage of the hydrogen as well as other
gaseous material. The open end of the guard member 51 is secured to
the header 46a by welding or other connecting means.
[0066] The purifier core unit 41 is formed of a porous ceramic body
41a with an outer hydrogen permeable metal coating 41b, with
presently known materials such as palladium or a palladium copper
alloy coating, forming a hydrogen selective membrane, and thus a
hydrogen purifier core unit 41. The reformed gases pass freely
through the guard 51 into the core unit 41. The hydrogen gas only
passes into the inner collection chamber 41c of the core unit 41 as
a result of traversing the outer hydrogen selective membrane 41b.
The guard 51 may take the form of a porous wall, an apertured wall
or even a tubular member directing the free hydrogen toward the end
thereof, with the hydrogen discharging therefrom, into the membrane
unit. Where the catalyst is in the form of one or more monolithic
catalyst elements or units mounted in spaced relation to the
selective membrane unit or units, the guard 51 may not be
necessary.
[0067] Referring to FIG. 7a, the flange 47 is recessed and
telescoped over the outer end of the tube 45 and is welded to the
exterior of the tube 45 as at 47a. The header 46a is bolted to the
flange 47 with a high pressure sealed gasket 52a therebetween. The
illustrated sealed joint (FIG. 7a) includes a copper seal ring 52a
located between the flange 47 and header 46a. A sharp sealing edge
52c projects outwardly from 47 and 46a into embedded engagement
with the copper ring 52a upon tightening of the securement bolts
53. The seal establishes a high pressure closure to confine
reformed gases within vessel 40. Other suitable seals may be used
in the preferred system, and in other systems may be constructed
without a removable cover structure. For example, end piece 46a may
be welded or brazed to the end of tube 45 for a permanent closure
of pressure vessel 40.
[0068] The input/output lines are sealed within header 46a and are
coupled to the several passages within the core unit 41 and
catalyst chamber 7 of the illustrated embodiment, as follows.
[0069] A feedstock fuel line 60 is secured in sealed relation to
the header 46a. The fuel line 60 extends inwardly into the
catalyst-filled chamber 7, and through the catalyst 50 to the inner
end portion of the chamber. The inner end of line 60 terminates,
close to the end wall 46 to feed the hydrogen rich feedstock fuel
into the closed end of the catalyst filled chamber 7, under
appropriate pressure, to move the feedstock axially through the
catalyst 50 toward the header 46a. An alternate arrangement within
the scope of this invention (not shown) utilizes a feedstock
delivery tube 60 and a raffinate exit tube 63 which extends the
length of catalyst bed 7, where the tubes are closed at the ends
and perforated, such that the gas flows between the perforated
tubes rather than down the axial length of the catalyst bed. Other
arrangements within the pressure vessel apparent to those skilled
within the art can be implemented as well.
[0070] A hydrogen recovery line 62 is secured within the header 46a
and terminates at the inner core chamber 41c of core unit 41 and
serves to recover the free hydrogen which has passed through the
membrane 41b of purifier core unit 41.
[0071] A raffinate line 63 is secured to the header 46a in
alignment with the lower or bottom side of the catalyst chamber 7.
The pressurized feedstock passes through the catalyst 50 and exits
as raffinate through the raffinate line 63 under pressure. The
raffinate generally contains a significant level of hydrogen and
functions as a fuel for the catalytic burner in the air passageway,
as hereinafter described.
[0072] The raffinate at the outlet of the catalyst, downstream of
the purifier unit 41, can provide a fuel to a catalytic or other
burner unit. Unreformed fuel, unrecovered hydrogen, and
side-reaction products such as carbon monoxide or methane can serve
to function as a fuel in a catalytic or other burners. The
particulars of gases contained in the raffinate depend upon the
fuel type, steam-to-carbon ratio, pressure, catalyst type, flow
rate, and temperature, and may also vary depending on the time on
stream of the catalyst. The reformed feedstock with hydrogen
removed by purifier 41 is generically identified herein as
raffinate, which will cover all reformed feedstock exiting a
catalyst unit and a hydrogen purification unit and coupled to the
system burner, as disclosed herein, as well as such fuel when
combined with or replaced by a separate fuel source.
[0073] The container 42 and particularly the tubular wall 45 has
spaced and heat conductive fins 59 intimately secured, as by
brazing or other high heat transmitting connection, to the
container wall 45. The fins 59 are shown as rectangular members
which are shaped and formed to fit within the corresponding opening
in the enclosure for optimal heating of the catalyst and generation
of purified hydrogen, as hereinafter described. The fins 59 are
spaced, with size and positioning selected to provide rapid heating
of the vessel, while yielding a minimal pressure drop for the
laterally passing flue gas flow. The fins 59 are preferably formed
of a suitable material such as copper for rapid heat transfer to
the vessel, and particularly to catalyst 50.
[0074] The pressure vessel 40 (FIG. 4) is removably secured within
an opening 65 in the enclosure 36 by a plate 64 secured to the
header 46a and to the enclosure frame structure by attachment
screws 65a. The finned vessel 40 is enclosed within an internal
wall structure to define an air/fuel inlet passageway and an outer
exhaust passageway, as hereinafter described.
[0075] The finned pressure vessel 40 and particularly purifier core
unit 41 thereof may require replacement in the event that a breach
or other degradation of membrane 41b occurs, or if the catalyst
activity declines significantly due to coking, poisoning, aging, or
other reasons. The other components are expected to have a long
life.
[0076] As shown, the finned pressure vessel 40 is removable as a
unit. The illustrated header 46a may be released from flange 47 and
replaced by a new header with a new core unit and guard unit within
the finned container 42. The catalyst may also be replaced during
this operation, which is particularly straightforward if the
catalyst is formed as a monolithic annular piece rather than the
granular material illustrated as 50. The illustrated unit thus
provides for a low cost replacement purifier 41 and pressure vessel
40 for simple serviceability and long life operation of the
reformer.
[0077] The feedstock feed line 60, the hydrogen (H.sub.2) recovery
line 62 and the raffinate line 63 are secured to header 46a in
spaced relation for inputting the feedstock and withdrawing the
purified hydrogen and the raffinate, relative to container 42, as
shown in FIGS. 8 and 9. Each line is similarly constructed with a
like line coupling unit 67 which may be released and later
re-sealed when servicing the unit.
[0078] The raffinate line 62 additionally may have a larger
releasable coupling 68 between header 46a and the coupling 67 to
open the line 63. This provides convenient means for replacing the
granular catalyst 50, as may be periodically required. As
previously mentioned, when the catalyst consists of one or more
monolithic members, header 46a must be removed to replace the
monolithic catalyst, in which case coupling 68 becomes
unnecessary.
[0079] The pressure vessel 40 is removably mounted within the
enclosure 36, as shown in FIGS. 4, 8 and 9-9b by fastening screws
65a. The housing enclosure 36 further contains a variety of
interior walls and flow directing means to channel the heating
gases through the enclosure. As best shown in FIG. 9b, an upper
vertical divider wall 69 divides the air inlet plenum 90 from the
exhaust gas plenum 91, extending between and abutting recuperator
assembly 30 and the top of enclosure 36, as well as the sides of
enclosure 36 to form an effective barrier between plenums 90 and
91. Below the recuperating assembly 30, rigid thermally insulating
vertical divider wall 70 further separates the gas flow. Vertical
wall 70 abuts and seals to rigid thermally insulating horizontal
wall 71. Horizontal wall 71 contains an opening 74 permitting the
mixed air and raffinate to flow into catalytic burner 75; otherwise
horizontal wall 71 abuts and seals against the outer enclosure 36
and vertical wall 70 to prevent the flow of gases elsewhere.
Horizontal wall 71, in combination with the bottom and sides of
enclosure 36 and the spaced fins 59 of vessel 40, forms a
passageway 74b for flue gas 75a for heating fins 59 and the
interior of vessel 40. Downstream of vessel 40, vertical flue gas
divider wall 73 formed of rigid thermally insulating material,
abutting and sealing against wall 71 and sides of enclosure 36,
directs the flue gas through passageway 76 in its opening 78. Wall
73 and the enclosure 36 further define a vertical passage way for
flue gas 79, containing heat exchanger 5.
[0080] Heat exchanger 5, illustrated as several coils of finned
tubing (FIGS. 9a and 9b) is connected within the feedstock line 60
which is connected to the incoming feedstock line 4 to the catalyst
bed, as hereinafter described. The finned tubing 5 is located in
that portion of exhausting flue gas 79 passing therethrough and is
effective for preheating the feedstock in heat exchanger 5 prior to
its sequential introduction into line 6, connector 67, and line 60
arriving at the catalyst 50.
[0081] Referring to FIGS. 1, 4, 8 and 9, the raffinate supply
connection from the reformer vessel 40 to the burner 75 is
illustrated, with the lines coupling for preheating the feedstock.
Raffinate line 63 exits vessel 40 through coupling 68 and 67 to
raffinate line 8 (FIG. 1). Raffinate line 8 passes through heat
exchanger 9, and then into control section 37 containing
feedstock/raffinate back pressure regulator 10. The back pressure
regulator 10 depressurizes the raffinate where it then is allowed
to combine with fuel cell bleed hydrogen before arriving at burner
feed line 83. Burner feed line 83 then passes into enclosure 36 to
the burner distributor. An illustrative burner distributor is shown
in FIG. 13 showing a tee fitting 86 and two perforated distributors
85 and 85a. 85 and 85a are shown in FIGS. 9, 9a, and 9b as well,
where they are positioned to mix the raffinate with the incoming
burner air prior to arrival at burner 75.
[0082] Each tube 85-85a is hollow and sealed at the outer most
ends. Each tube 85-85a is preferably a porous or perforated
material, such as a ceramic material, a sintered metal, or
perforated tubing or other like functioning material. At the start
of the system operation, the inlet air 74a in passageway 74 is
relatively cold air and the raffinate cannot be generated until the
catalytic bed is at a temperature sufficient to process feedstock.
To initiate the bed activation, and to preheat the burner 75 to a
temperature sufficient to allow for catalytic combustion of
raffinate, an auxiliary heating source is normally required during
start-up. An electrical heater 88 is shown mounted (FIGS. 9-9a)
above the burner 75. The heater 88 is turned on automatically
during the start up of the system to heat the inlet air supply to
the temperature necessary for raising the catalytic burner
temperature to the "light-off" temperature, and the catalyst bed to
a temperature sufficient to reform the fuel. Once this temperature
is achieved the pump 3 may start pumping feedstock into the device,
resulting in generation of the hydrogen freeing reaction in the
catalyst 50 and the subsequent raffinate fuel for firing of the
burner 75. For alcohol based feedstock, the necessary catalyst bed
temperature is on the order of 250-500.degree. C., depending on the
fuel and catalyst choice, and the catalytic burner light-off
temperature for hydrogen in the raffinate is above approximately
100.degree. C. After the "light-off" state is established at the
burner, the heater 88 for heating of the inlet air supply may be
terminated because the raffinate entering the burner 75 is then
adequate to maintain the proper heating of the catalyst. The
preheating of the feedstock as described in the preferred
construction, further maintains the proper reactance in the
catalyst without an auxiliary heat source after light-off.
[0083] The raffinate (FIGS. 9 and 9b) is mixed with the air flow in
the air inlet passageway 74 and the mixture passes into and through
the burner 75 which burns to form high temperature fluid or flue
gas 75a. The flue gas 75a flows directly into the inlet passageway
74b, to and over pressure vessel 40 as shown in FIGS. 4, 8 and 9b.
The heated flue gas 75a passes through the fins and over the
container 42 of pressure vessel 40 as the only exit from the supply
or inlet passageway 74b. The fins 59 are suitably spaced transfer
the heat into the pressure vessel 40 to heat the catalyst 50 and
thereby generate the hydrogen for capture within the core unit 41.
Although the feedstock is preheated, as previously described, the
reforming reactions requires the additional heat input from the
burner to compensate for the endothermic reaction to produce
hydrogen.
[0084] The heating of the catalyst 50 may include special
distribution on the axis of the bed or catalyst unit. An optimal
heat distribution curve 100 and a resulting reaction curve 101 are
shown in FIG. 12. The heat distribution curve 100 is high over
approximately the first half of the catalyst 50 and then gradually
decreases to a low level adjacent the exit or discharge end of the
catalyst, since the bulk of the endothermic reaction occurs at the
beginning of the catalyst bed. The resulting reaction curve 101 for
generating the free hydrogen includes a rapid increase in the
hydrogen over the high heat input portion and then levels off to a
slight release curve to the exit or discharge end of the catalyst
50.
[0085] Since the heating requirements are higher at the beginning
of the catalyst bed, a higher heat flux is desired in this region
compared to the exit of the catalyst bed. This can be accomplished
by decreasing the spacing of the fins nearer the feedstock inlet,
or by increasing the temperature of flue gas 75a at the nearer the
feedstock inlet, or a combination of both.
[0086] FIG. 13 illustrates a special construction of the raffinate
input to the burner 75 for the optional heating distribution of the
vessel. The raffinate distribution holes in 85 and 85a are varied
to supply a richer raffinate/air mix nearer the feedstock inlet end
of the catalyst bed 7, while the exit ends of 85 and 85a have fewer
holes, providing a leaner raffinate/air mix. The richest and
therefore hottest flue gas is therefore applied at the entrance end
of the catalyst bed 7 and the leanest and therefore coolest flue
gas at the exit end of the bed 7, generally in accordance with the
illustration.
[0087] In an alternate configuration the catalytic burner may
reside on the surface of the vessel or on the fins secured to the
vessel. Methods for forming catalytic surfaces via methods of
coating are known to those skilled in the art and are not discussed
in further detail. If the catalytic burner is coated on the fins,
the fins are preferably closely spaced throughout the length of the
catalyst unit. This is necessary to insure that un-burned raffinate
does not slip past the fins and flow into the exhaust passageway 76
with the exiting flue gas 79. In this case it is also preferable to
use the graduated burner diffuser illustrated in FIG. 13.
[0088] A preferred feedstock heat exchanger illustrated as finned
unit 5 is shown in FIGS. 4, 8 and 8a. The lines 8 and 11 exiting
vessel 40 via couplings include lengths of bare metal tubes which
are assembled with a metal tube of cold feedstock line 4 in
positive abutting engagement. The bare metal tubes are held in
abutting and heat transfer engagement by a suitable coupling,
preferably by a heat transfer bond; for example, brazing or welding
the three tubes to each other throughout a substantial length as at
84c, or otherwise similar by connecting the tubes with other
heat-transmitting and bonding materials. The bonded tubes 4, 8, and
11 may be covered by an outer wrap of an insulating cloth 84b over
the bonded tubes. The bonded lines are assembled in a counterflow
assembly with the coldest end of the feedstock line 4 abutting the
coldest ends of lines 8 and 11. This serves to minimize heat
losses, increasing the efficiency of the reformer. The heat
exchanger 5 also serves to cool the hydrogen and raffinate prior to
arriving at regulators 12 and 10, respectively, preventing
overheating of the regulators and allowing for a lower cost, lower
operating temperature regulator.
[0089] The bonded lines 4, 8, and 11 are shown in U-shape
configuration with equal side ends to create an extended length.
The overall length of the legs is related to and generally
corresponds to the length of vessel 40 and the inner core unit so
that the heat exchanger unit is sized or scaled to the system size
with the vessel 40 and the inlet and exhaust as well as for system
scaling as hereinafter discussed.
[0090] This also provides a relatively simple but highly effective
system for heating of the feedstock. Other systems of coupling the
lines to each other may be used. As a result of the recovery of
heat and preheating of the feedstock, the required heating of the
catalyst bed for effective generation of purified hydrogen is
reduced, and the counterflow arrangement of the heat exchanger
increases efficiency.
[0091] As shown in FIGS. 8-9b, the air inlet plenum 90 is formed to
one side of wall 69 and extended over one half of the top of
enclosure 36. Similarly, the other half of the top of enclosure 36
contains exhaust chamber 91 to the other side of the dividing wall
69. Ambient air from fan 20 arrives in plenum 90 through air inlet
38, and exhaust leaving plenum 91 exits via exhaust aperture
92.
[0092] In accordance with the preferred construction and as shown
in FIGS. 1 and 8-9b, a heat recovery structure 30 couples in
counterflow fashion the heat in the exhaust flue gas 78a to the air
arriving through air inlet 38 as follows.
[0093] The air inlet chamber 90 of FIGS. 1, 8 and 9 is connected to
the air supply tube or passageway 38 shown in FIG. 2a-3. The
exhaust chamber 91 includes the exhaust opening 92 in the rear
structural wall, as shown in FIGS. 3, 8 and 9b.
[0094] A multiple plate assembly 30 is secured below wall 69,
spanning the inlet air and exhaust flue gas streams.
[0095] FIGS. 10 and 11 are enlarged pictorial views of the heat
transfer plate assembly 30 with enlarged plates 96 for clearly
illustrating one preferred construction of the heat recuperating
system for heating the incoming air supply. The multiple plate
assembly 30 includes a plurality of heat transfers plates 96
separated by heat insulating and fluid closing wall gasket members
97 which maintain separation of the incoming air with the exiting
flue gas, while allowing the plates 96 to pass through and span the
incoming air and exiting flue gas regions. The plates 96 may be
formed as like plates of a suitable metal such as copper, aluminum
or other materials which are a good heat transmitting material. The
illustrated diamond shaped openings 96a, or any other shaped
openings may be formed in the metal plates. The openings need not
have the same shape or size, nor are the openings in the adjacent
plates necessarily aligned with each other. The size and frequency
of the openings in the plates is scaled sufficient to allow for
easy passage of the air and flue gas with a minimal pressure drop
in the respective gas streams. The openings also allow for a high
surface area for transferring heat into and out of the plates.
[0096] The plates 96 and wall members 97 are preferably thin
elements. Typically, the plates 96 have a thickness of 0.005-0.100
inches, and more preferably 0.020-0.05 inches. The thickness of the
plates is scaled sufficient to yield a low temperature drop while
transmitting heat from the flue gas to the incoming air, and
depends somewhat on the metals used and the desired heat flux
needed through the plates. The separating wall members 97 may have
a similar thickness or may be thicker than the plates if desired.
The insulating properties of the members 97 are chosen to
sufficiently thermally isolate adjacent plates 96; this allows for
plates to operate at different temperatures thus permitting
counterflow heat exchange between the two gas streams. The lowest
plate, in contact with the hottest flue gas 78a, is therefore at
the highest temperature, while the highest plate, in contact with
the incoming ambient air, is at the lowest temperature.
[0097] As illustrated in FIG. 10, the separating wall member 97
does not encourage parallel alignment of plates 96 in recuperating
assembly 30. For this reason, member 97(a) is augmented with
extending legs 97b as shown in FIG. 11. Stacking of a plurality of
members 97 and 96 to form assembly 30 thus forces parallel
alignment of plates 96.
[0098] Although not illustrated, other embodiments of counterflow
heat exchange element 30 are possible. For example, in an annular
arrangement sealing member 97 becomes donut-shaped, and extending
legs 97b are no longer required to yield a parallel orientation of
plates 96, where the plates extend between an inner and outer
annulus for heat transfer. In yet another configuration, two
separate perforated plates may be folded into a serpentine pattern,
yielding parallel plates. These two pieces may be brazed together
with a thin piece of metal which serves as divider 97. One
serpentine assembly of parallel plates would extend into the air
plenum, while the other would extend into the flue gas plenum, and
the heat transfer between plenums would occur at the brazed joint
over the single metal divider 97. Other additional variations may
be obvious to those skilled in the art.
[0099] In summary, the illustrated embodiment discloses a preferred
construction for preheating the supply input air which is supplied
to burner 75. A practical assembly only needs to include plates or
other elements which provide effective heat transfer of the heat in
the exhaust gas to the inlet air via mounting of the elements in
sealed relation within a separating wall; within the broadest
aspect of the present invention.
[0100] The construction for the recovery of the heat in the exhaust
gas should include the relatively large cross-sectional flow areas
of the chambers and the associated air and exhaust passageways as
well as relatively large openings within the heat transfer plates
or other heat transfer elements forming like large openings such
that the structure creates a low pressure drop, and a resulting low
power consumption to supply air through fan 20.
[0101] Like consideration is given to the passageway associated
with the heating of the pressure vessel 40. Thus, the catalytic
burner 75 preferably has a relatively large cross-section and is
formed with a substantial plurality of like parallel passages in
the direction of the air/fuel flow therethrough.
[0102] For example, a two-inch deep burner having passages on the
order of 200 cells per square inch and of an extruded ceramic with
a precious metal coating is one example of a higher satisfactory
burner, in accordance with known construction. The recuperator for
heating the input air may likewise be formed from aluminum in an
expanded and rolled pattern with an open area approaching 40%.
[0103] The pressure vessel 40 is similarly and preferably
constructed with a relatively large finned construction and with
proper spacing of the fins to establish a low system pressure drop
in the gases passing over the vessel, as is heat exchanger 5.
[0104] The other heat recovery systems such as the preheat of the
feedstock fuel and the recovery of the heat from the purified
hydrogen and the reformed gases within the system also provide
significant results in producing an efficient and improved
reforming apparatus.
[0105] The combined structure with the special air and fuel
supplies including the heat exchanges at the air inlet and exhaust
passageways, the feedstock preheat coil, the coupled flow lines,
the catalytic burner and the finned pressure vessel may yield a
significantly low burner gas pressure drop. As a result, the
electrical power requirement for moving of the air and flue gases
into and through the unit is low. This, in combination with low
thermal losses, yields a corresponding increase in reformer
efficiency.
[0106] The unique characteristic of the illustrated design also
allows for cost effective scalable construction of the systems with
different maximum output levels. The several components and parts
of the illustrated embodiment with the linear axis permits
construction of the vessel of different capacity by designing the
linear length of the components to be directly related to the
desired capacity. Thus, each of the interacting components
including the burner area, heat exchange area, the catalyst volume,
purifier membrane area, the exhaust heat transfer system, the
counter flow heating unit coupling the feedstock line to the
raffinate line and/or the hydrogen line are directly related to the
length on the linear axis of the elements and components and
therefore the final structure, as disclosed herein.
[0107] For example, if the length of the pressure vessel is
doubled, the lengths of the air and exhaust chambers, the inlet air
supply and feedstock heat transfer units, and the burner and
related passageway will double, producing a doubled output
capacity.
[0108] The design and structure of the device is particularly
unique in allowing for the ease in scalability, but also provides a
cost effective service construction. In the purifier, the membrane
and catalyst component may require periodic replacement and is
readily replaced in the preferred embodiment. Service in the field
may thus consist of simply and easily replacing the entire finned
pressure vessel containing the purifier unit and catalyst, or
replacing the guard and core unit as attached to the header while
reusing the finned vessel and flange unit.
[0109] The illustrated embodiment may process any of a variety of
feedstocks. Although illustrated in the preferred embodiment using
a miscible water/fuel feedstock, separate fuel and water supply
means may be employed, for a variety of fuels, and which may
include various other steps such as fuel desulphurization, water
conditioning, and the like, in accordance with typical feed
conditioning steps as disclosed in the known art. Likewise, the
size and placement of the various components may be varied in
keeping with the present disclosure. For example, improvements in
membrane technology will allow for a much smaller membrane
collector area, and similar improvements in catalyst may allow for
a smaller catalyst volume.
[0110] The specific monitoring, operation, and control of the
reformer, with the typical user interface requirements such as LCD
display 22 and operator controls 23 (see FIG. 2), involve devices,
hardware, operating states, and algorithms previously disclosed and
known to those skilled in this art. A typical example can be found
in "PC-25 C On-Site Fuel Cell Power Plant Service Manual Volume 1",
ONSI Corporation (April 1996), and the like.
[0111] In summary, the present invention provides an improved and
unique reformer structure for generating of purified hydrogen from
the various fuels containing hydrogen. The illustrated preferred
embodiment of the invention also provides a reforming system which
is operable with a low pressure drop in the air supply system, with
a resulting cost effective system.
* * * * *