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Patent 2274286 Summary

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(12) Patent Application: (11) CA 2274286
(54) English Title: ROTARY PRESSURE SWING ADSORPTION APPARATUS
(54) French Title: APPAREIL ROTATIF D'ADSORPTION MODULEE EN PRESSION
Status: Dead
Bibliographic Data
(52) Canadian Patent Classification (CPC):
  • 183/21
(51) International Patent Classification (IPC):
  • B01D 53/047 (2006.01)
  • B01D 53/04 (2006.01)
  • B01D 53/06 (2006.01)
(72) Inventors :
  • CONNOR, DENIS J. (Canada)
  • JEZIOROWSKI, LES (Canada)
  • SHAW, IAN (Canada)
  • LARISCH, BELINDA (Canada)
  • KEEFER, BOWIE (Canada)
  • MCLEAN, CHRISTOPHER (Canada)
  • DOMAN, DAVID G. (Canada)
(73) Owners :
  • QUESTAIR TECHNOLOGIES INC. (Canada)
(71) Applicants :
  • QUESTOR INDUSTRIES INC. (Canada)
(74) Agent: OYEN WIGGS GREEN & MUTALA LLP
(74) Associate agent:
(45) Issued:
(22) Filed Date: 1999-06-09
(41) Open to Public Inspection: 2000-12-09
Examination requested: 2004-04-30
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data: None

Abstracts

English Abstract




Gas separation by pressure swing adsorption
(PSA) is performed within an apparatus having a
plurality of adsorbers cooperating with first and second
valve means in a rotary PSA module, with the PSA cycle
characterized by multiple intermediate pressure levels
between the higher and lower pressures of the PSA cycle.
Gas flows enter or exit the PSA module at the
intermediate pressure levels as well as the higher and
lower pressure levels, under substantially steady
conditions of flow and pressure. The PSA module
comprises a rotor containing laminated sheet adsorbers
and rotating within a stator, with ported valve faces
between the rotor and stator to control the timing of
the flows entering or exiting the adsorbers in the
rotor.


Claims

Note: Claims are shown in the official language in which they were submitted.




-34-

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A rotary module for pressure swing adsorption
separation of a gas mixture containing components
which are respectively more readily adsorbed and
less relatively adsorbed component under pressure
increase over an adsorbent material; the rotary
module comprising a stator and a rotor with an axis
of rotation, the stator and rotor being mutually
engaged in fluid communication across a first rotary
valve surface and a second rotary valve surface both
centred on the axis of rotation; the stator having a
plurality of first function compartments each
opening into the first rotary valve surface in an
angular sector thereof, and a plurality of second
function compartments each opening into the second
rotary valve surface in an angular sector thereof;
the rotor having a plurality of angularly spaced
adsorber elements wherein the adsorbent material is
supported in layered adsorbent sheets contacting
flow channels defined by spacers between adjacent
adsorbent sheets, each such flow channel extending
in a flow direction between a first end
communicating by a first aperture to the first valve
surface and a second end communicating by a second
aperture to the second valve surface; and with means
to rotate the rotor such that each of the first
apertures is opened in fluid communication to the
first function compartments by rotation of the rotor
bringing the apertures sequentially into the angular
sector of each first function compartment, while
each of the second apertures is opened in fluid
communication to the second function compartments by
rotation of the rotor bringing the apertures
sequentially into the angular sector of each second



-35-



function compartment so as to achieve cycling of the
pressure in each adsorber element between an upper
pressure and a lower pressure.
2. The rotary module of claim 1, with means to provide
the gas mixture to a first function compartment at
an upper pressure, with means to exhaust gas
enriched in a more readily adsorbed component from a
first function compartment at a lower pressure, and
with means to deliver gas enriched in a less readily
adsorbed component from a second function
compartment at substantially the upper pressure.
3. The rotary module of claim 2, wherein the function
compartments also include a plurality of
pressurization compartments for subjecting the
adsorber elements to a plurality of incremental
pressure increases between the upper and lower
pressures.
4. The rotary module of claim 3, wherein the
pressurization compartments include feed
pressurization compartments opening into the first
rotary valve surface for delivering the gas mixture
to the adsorber elements at incrementally different
pressures intermediate between the upper and lower
pressures.
5. The rotary module of claim 3, wherein the
pressurization compartments include light reflux
return compartments opening into the second rotary
valve surface for delivering gas enriched in a less
readily adsorbed component to the adsorber elements
at a plurality of incrementally different pressures.



-36-



6. The rotary module of claim 2, wherein the function
compartments also include a plurality of blowdown
compartments for subjecting the adsorber elements to
a plurality of incremental pressure drops between
the upper and lower pressures.
7. The rotary module of claim 6, wherein the blowdown
compartments include light reflux exit compartments
opening into the second stator valve surface for
removing gas enriched in a less readily adsorbed
component as cocurrent blowdown from the adsorber
elements at a plurality of incrementally different
pressures.
8. The rotary module of claim 6, wherein the blowdown
compartments include countercurrent blowdown
compartments opening into the first stator valve
surface for removing gas enriched in a more readily
adsorbed component from the adsorber elements at a
plurality of incrementally different pressures.
9. The rotary module of claim 2, wherein the function
compartments are disposed around the respective
valve surfaces for conveying gas to and from the
adsorber elements in a common predetermined sequence
for each adsorber element, the sequence for each
adsorber element comprising the steps of (1)
supplying the gas mixture at the upper pressure from
a first function compartment as a feed compartment
to the adsorber element first end while removing gas
enriched in a less readily adsorbed component as a
light product gas at substantially the upper
pressure from the adsorber element second end to a
second function compartment as a light product
compartment, (2) releasing gas enriched in a less
readily adsorbed component form the adsorber second



-37-



end as light reflex gas so as to reduce the pressure
in the adsorber to an intermediate pressure level,
(3) releasing gas enriched in a more readily
adsorbed component form the adsorber first end as
countercurrent blowdown gas so as to reduce the
pressure in the adsorber from an intermediate
pressure level, (4) removing gas enriched in a more
readily adsorbed component as a heavy product gas at
the lower pressure from the adsorber element first
end to a first function compartment as a heavy
product compartment, and (5) supplying light reflex
gas at a pressure intermediate the upper and lower
pressure to a light reflex return compartment and
thence to the adsorber element second end.
10. The rotary module of claim 9, with the sequence also
including after step (5) a step (6) supplying the
gas mixture at an intermediate pressure less than
the upper pressure to a feed pressurization
compartment and thence to the first end of the
adsorber element.
11. The rotary module of claim 1, wherein each function
compartment is shaped to provide uniform gas flow
through the corresponding sector of the first or
second rotary valve face.
12. The rotary module of claim 1, wherein each of the
function compartments simultaneously communicates
with apertures to at least two angularly spaced
adsorber elements so as to provide substantially
uniform gas flow at substantially steady pressure
through each of the function compartments.



-38-



13. The rotary module of claim 1, wherein dead volume
associated with the first and second apertures is
substantially zero.
14. The rotary module of claim 1, wherein each said
adsorber element includes a laminated sheet
adsorber.
15. The rotary module of claim 1 with fluid sealing
means cooperating with the stator to limit fluid
leakage between function compartments in each of the
first and second rotary valve sealing faces, and to
substantially prevent fluid leakage from or into
each of the first and second rotary valve faces.
16. The rotary module of claim 1, with the rotor having
a first rotor face for engaging the fluid sealing
means in the first rotary valve surface and a second
rotor face for engaging the fluid sealing means in
the second rotary valve surface, the first rotor
face being penetrated by the first apertures and the
second rotor face being penetrated by the second
apertures, for cyclically exposing each adsorber
element to a plurality of discrete pressure levels
between the upper and lower pressures.
17. The rotor module of claim 16, wherein each said
adsorber element is formed from a plurality of
adsorbent sheets, each said sheet including a
reinforcement material, an adsorbent material
deposited therein, a binder for securing the
adsorbent material, and a spacer provided between
each adjacent pair of adsorbent sheets for providing
the flow channel therebetween.



-39-



18. The rotor module of claim 17, wherein the
reinforcement material is selected from a mineral or
glass fiber matrix such as a woven or non-woven
glass fiber scrim, a metal wire matrix such as a
wire mesh screen, or a metal foil such as an
anodized aluminum foil.
19. The rotor module of claim 17, wherein the adsorbent
material comprises zeolite crystallites.
20. The rotor module of claim 16, wherein the adsorber
elements include a pair of opposite ends, and each
said aperture is disposed immediately adjacent to a
respective one of the opposite ends.
21. The rotary module of claim 17, with the rotor having
an annular volume containing the adsorber elements,
with the flow direction being axial with respect to
the axis of rotation, and with the first rotor face
being a circular annular end surface of the rotor
and the second rotor face being a circular annular
end surface of the rotor, the first and second rotor
faces being substantially normal to the axis of
rotation.
22. The rotor module of claim 21, wherein the adsorber
elements are formed of flat stacks of the adsorbent
sheets, with the sheets of each adsorber element
substantially radially aligned and parallel to the
axis of rotation, and with separators between the
adsorbent elements.
23. The rotor module of claim 21, wherein the adsorber
elements are formed of curved stacks of the
adsorbent sheets, with the sheets of each adsorber
element substantially radially and spirally aligned



-40-
and parallel to the axis of rotation, and the stacks
are nested spirally so as to substantially fill the
annular volume of the rotor.
24. The rotor module of claim 21, with the rotor having
a cylindrical core coaxial to the axis of rotation
and internal to the annular volume, with at least
some of the spacers between the adsorbent sheets
being spacer separators substantially impervious to
fluid flow transverse to the flow direction and
extending the entire length between the first and
second ends of the flow channels between the spacer
separators and defined thereby, the adsorbent
elements being formed by spirally rolling at least
one adsorbent sheet with the spacer separators
evenly spaced around the cylindrical core as a
mandrel to form a spiral roll substantially filling
the annular volume, and with each pair of adjacent
spacer separators between adjacent adsorbent sheet
layers defining a distinct adsorber element.
25. The rotor module of claim 21, with the rotor having
a cylindrical core coaxial to the axis of rotation
and internal to the annular volume, the adsorbent
sheets are parallel to the axis of rotation and
extend in substantially radial and spirally curved
orientation from the core, spacers are provided
between each adjacent pair of said adsorbent sheets
to define axial flow channels therebetween, with at
least some of the spacers between the adsorbent
sheets being spacer separators substantially
impervious to fluid flow transverse to the flow
direction and extending the entire length between
the first and second ends of the flow channels
between the spacer separators and defined thereby,
with each adsorber element being defined by the flow



-41-
channel between each adjacent pair of spacer
separators and between an adjacent pair of adsorbent
sheets, so that the number of adsorber elements is
equal to the number of adsorbent sheets multiplied
by the number of flow channels defined by the number
of spacer separators between each pair of adsorbent
sheet, and the adsorbent sheets are nested spirally
on the spacers so as to substantially fill the
annular volume of the rotor.
26. The rotary module of claim 17, with the rotor having
an annular volume containing the adsorber elements,
with the flow direction being substantially radial
with respect to the axis of rotation, and with the
first rotor face being an external cylindrical
surface of the rotor and the second rotor face being
an internal cylindrical surface of the rotor.
27. The rotor module of claim 26, wherein the adsorber
elements are formed of flat stacks of the adsorbent
sheets, with the sheets of each adsorber element in
planes that are substantially radially aligned and
parallel to the axis of rotation, and with
separators between the adsorbent elements.
28. The rotor module of claim 26, wherein the adsorber
elements are formed of curved stacks of the
adsorbent sheets, with the sheets of each adsorber
element substantially radially and spirally aligned
and parallel to the axis of rotation, and the stacks
are nested spirally so as to substantially fill the
annular volume of the rotor.
29. The rotor module of claim 26, wherein the adsorber
elements are formed of flat stacks of the adsorbent
sheets, with the sheets of each adsorber element in



-42-
planes that are substantially radially aligned and
normal to the axis of rotation, and with the spacers
defining substantially radially aligned flow
channels between adjacent sheets.
30. The rotor module of claim 29, wherein the adsorber
elements are provided in separate trapezoidal
angular sectors with respect to the axis of
rotation, and with fluid impermeable partitions
between adjacent angular sectors.
31. The rotor module of claim 30, with at least some of
the spacers between the adsorbent sheets in the
trapezoidal angular sectors being spacer separators
substantially impervious to fluid flow transverse to
the radial flow direction and extending the entire
length between the first and second ends of the flow
channels between the spacer separators and defined
thereby, with each pair of adjacent spacer
separators between adjacent adsorbent sheet layers
defining a distinct adsorber element within the
angular sector so as to define a plurality of
angularly spaced and distinct adsorber elements
therein.
32. The rotor module of claim 30 in which the adsorber
elements are externally assembled, activated and
then vacuum packed into aluminum foil so as to
prevent deactivation prior to their installation,
with the aluminum foil removed from the first and
second ends of the adsorbent element prior to
commissioning.
33. The rotor module of claim 29, the adsorber sheets
provided as circular annular discs with spacers
defining a radial flow direction, and the said


-43-

sheets being stacked concentrically with the axis of
rotation with the spacers defining radially aligned
flow channels between adjacent sheets, with at least
some of the spacers between the adsorbent sheets
being spacer separators substantially impervious to
fluid flow transverse to the radial flow direction
and extending the entire length between the first
and second ends of the flow channels between the
spacer separators and defined thereby, the adsorbent
elements substantially filling the annular volume,
and with each pair of adjacent spacer separators
between adjacent adsorbent sheet layers defining a
distinct adsorber element.
34. The rotor module of claim 25, wherein the adsorbent
sheets are parallel to the axis of rotation,
substantially radially oriented and spirally curved,
the adsorber elements are formed by each adjacent
pair of spirally curved adsorbent sheets with
spacers to define flow channels therebetween, with
each adsorber element being defined by the flow
channel between an adjacent pair of adsorbent
sheets, so that the number of adsorber elements at
separate angular spacings is equal to the number of
adsorbent sheets, and the adsorber elements are
nested spirally so as to substantially fill the
annular volume of the rotor.
35. The rotor module of claim 29 or 30, in which the
adsorber elements are externally assembled,
activated and then vacuum packed into aluminum foil
so as to prevent deactivation prior to their
installation, with the aluminum foil removed from
the first and second ends of the adsorbent element
prior to commissioning.



-44-
36. The rotor module of claim 29, in which the spacers
are tapered from a greater height at the first end
to a smaller height at the second end of the
adsorber elements, so that the angular width of the
adsorbent element is constant in the radial
direction.
37. The rotor module of claim 29, in which the adsorbent
sheets are tapered from a greater thickness at the
first end to a smaller thickness at the second end
of the adsorber elements, so that the angular width
of the adsorbent element is constant in the radial
direction.
38. The rotor module of claim 1, in which the spacers
are formed on each adsorbent sheet by printing or
calandaring onto the sheet a pattern of parallel
ridges extending in the flow direction, so as to
define the flow channels between adjacent ridges.
39. The rotor module of claim 1, in which the spacers
are formed on each adsorbent sheet by printing or
calandaring onto the sheet a staggered pattern of
raised bosses, so as to define the flow channels
extending in the flow direction between the raised
bosses.
40. The rotor module of claim 1, in which the spacers
are provided as a woven mesh between adjacent pairs
of adsorbents sheets, so as to define the flow
channels extending in the flow direction
therebetween.
41. The rotor module of claim 1, in which the spacers
are provided as longitudinal members extending in
the flow direction between adjacent pairs of



-45-
adsorbents sheets, so as to define the flow channels
between the longitudinal members, and with bracing
members interconnecting adjacent longitudinal
members to as to establish and maintain their
spacing, the bracing members being narrower than the
channel height so as to avoid excessive obstruction
to flow in the flow channels.
42. The rotor module of claim 1, in which the
longitudinal members are provided as wires or metal
strips, and the bracing members are thinner wires or
metal strips woven in a Dutch weave pattern to
establish the spacers as a woven mesh.
43. The rotor module of claim 1, in which the spacers
are provided as a metal foil between adjacent pairs
of adsorbents sheets, with raised folded or embossed
ridges or grooves or perforations in the foil so as
to define flow channels contacting the adsorbent
material on the adjacent adsorbent sheet on each
side of the foil and extending in the flow
direction.
44. The rotor module of claim 43, in which the metal of
the foil is aluminum.
45. The rotor module of claim 43, in which the adsorbent
element stack is terminated by the spacers, and the
spacers at the terminating ends of the adsorber
element stack contact adsorbent material only on the
their inside side, with the spacers at the
terminating ends being configured to present the
same flow channel volume and flow resistance as for
spacers between a pair of adsorbent sheets at
intermediate positions within the stack, so that all
flow channels are thus substantially identical in



-46-
their contact with the adsorbent material and in
their hydraulic characteristics.
46. The rotor module of claim 43 in which the adsorbent
sheets are formed by coating the adsorbent material
on each side of an aluminum foil, except for the
adsorbent sheets at the terminating ends of an
adsorber element stack which are coated on one side
to be installed as the inside side only, so that all
flow channels contact the adsorbent material on both
sides, and are thus substantially identical.
47. The rotor module of claim 2 coupled to
compression/expansion machinery for maintaining the
function ports at a plurality of discrete pressure
levels between an upper pressure and a lower
pressure for maintaining uniform gas flow through
the first and second function compartments.
48. The rotor module of claim 47, wherein the function
compartments include a plurality of gas feed
compartments, and the compression/expansion
machinery comprises a multi-stage compressor
including a plurality of discharge ports, each said
discharge port being coupled to a respective one of
the feed compartments for delivering feed gas to the
adsorber elements at a plurality of pressure
increments.
49. The rotor module of claim 48, wherein the
multi-stage compressor comprises a centrifugal compressor
having a plurality of stages, at least some of which
stages including a discharge port intermediate
between the stages and coupled to a respective one
of the feed compartments.


-47-

50. The rotor module of claim 48, wherein the function
compartments include a plurality of blowdown
compartments, and the compression/expansion
machinery includes a multi-stage vacuum pump coupled
to the compressor, the vacuum pump including a
plurality of inlet ports, each said inlet port being
coupled to a respective one of the blowdown
compartments for receiving blowdown gas from the
adsorber elements at a plurality of pressure
increments.
51. The rotor module of claim 48, wherein the function
compartments include a plurality of blowdown
compartments, and the pressure swing adsorption
system includes a plurality of throttle orifices
coupled to the blowdown compartments for releasing
blowdown gas from the adsorber elements at a
plurality of pressure increments.
52. The rotor module of claim 47, wherein the function
compartments include a plurality of light reflux
exit compartments, and the compression/expansion
machinery comprises an expander receiving cocurrent
blowdown gas from the light reflux exit compartments
and returning that gas to light reflux return
compartments.
53. The rotor module of claim 52, in which a light
product compressor receives and compresses light
product gas from the light product compartment, with
the compressor powered by the expander.
54. Adsorber element for contacting an adsorbent
material to a fluid mixture, the adsorber element
being formed from layered thin adsorbent sheets
comprising the adsorbent material and a


-48-

reinforcement material, with spacers between the
sheets to establish flow channels in a flow
direction tangential to the sheets and between
adjacent pairs of sheets, the adsorber elements
having first and second ends defining a flow path in
the flow direction through the adsorber element and
along the flow channels established by the spacers.
55. Adsorber element of claim 16, wherein each said
adsorber element is formed from a plurality of
adsorbent sheets, each said sheet including a
reinforcement material, an adsorbent material
deposited therein, a binder for securing the
adsorbent material, and a spacer provided between
each adjacent pair of adsorbent sheets for providing
the flow channel therebetween.
56. The adsorber element of claim 54, wherein the
reinforcement material is selected from a mineral or
glass fiber matrix such as a woven or non-woven
glass fiber scrim, a metal wire matrix such as a
wire mesh screen, or a metal foil such as an
anodized aluminum foil.
57. The adsorber element of claim 54, wherein the
adsorbent material comprises zeolite crystallites.
58. The adsorber element of claim 54, formed as a flat
stack of the adsorbent sheets.
59. The adsorber element of claim 58, in which the
adsorbent sheets and the flat stack are rectangular.
60. The adsorber element of claim 58, in which the
adsorbent sheets and the flat stack are trapezoidal,
with a wider edge at the first end of the adsorber



-49-

element than at the second end of the adsorber
element, so that the flow channel is tapered from
the first end to the second end.

61. The adsorber element of claim 54, formed as a curved
stack of the adsorbent sheets.

62. The adsorber element of claim 54, within an annular
volume having a cylindrical core coaxially
therewithin, the adsorbent sheets are parallel to
the core and extend in substantially radial and
spirally curved orientation from the core, spacers
are provided between each adjacent pair of said
adsorbent sheets to define axial flow channels
therebetween, and the adsorbent sheets are nested
spirally on the spacers so as to substantially fill
the annular volume.
63. The adsorber element of claim 54, in which the
adsorbent sheets are activated before assembly into
the elements, and then vacuum packed into aluminum
foil so as to prevent deactivation prior to their
installation, with the aluminum foil removed from
the first and second ends of the adsorbent element
prior to commissioning.
64. The adsorber element of claim 54, in which the
adsorber sheets are assembled, then activated and
then vacuum packed into aluminum foil so as to
prevent deactivation prior to their installation,
with the aluminum foil removed from the first and
second ends of the adsorbent element prior to
commissioning.
65. The adsorber element of claim 54, with the adsorber
sheets provided as circular annular discs with


-50-

spacers defining a radial flow direction, and the
said sheets being stacked concentrically in an
annular volume with the spacers and the adsorbent
elements substantially filling the annular volume.
66. The adsorber element of claim 54, in which the
spacers are tapered from a greater height at the
first end to a smaller height at the second end of
the adsorber elements, so that the flow channels are
likewise tapered.
67. The adsorber element of claim 54, in which the
adsorbent sheets are tapered from a greater
thickness at the first end to a smaller thickness at
the second end of the adsorber elements.
68. The adsorber element of claim 54, in which the
spacers are formed on each adsorbent sheet by
printing or calandaring onto the sheet a pattern of
parallel ridges extending in the flow direction, so
as to define the flow channels between adjacent
ridges.
69. The adsorber element of claim 54, in which the
spacers are formed on each adsorbent sheet by
printing or calandaring onto the sheet a staggered
pattern of raised bosses, so as to define the flow
channels extending in the flow direction between the
raised bosses.
70. The adsorber element of claim 54, in which the
spacers are provided as a woven mesh between
adjacent pairs of adsorbents sheets, so as to define
the flow channels extending in the flow direction
therebetween.



-51-

71. The adsorber element of claim 54, in which the
spacers are provided as longitudinal members
extending in the flow direction between adjacent
pairs of adsorbents sheets, so as to define the flow
channels between the longitudinal members, and with
bracing members interconnecting adjacent
longitudinal members to as to establish and maintain
their spacing, the bracing members being narrower
than the channel height so as to avoid excessive
obstruction to flow in the flow channels.
72. The adsorber element of claim 54, in which the
longitudinal members are provided as wires or metal
strips, and the bracing members are thinner wires or
metal strips woven in a Dutch weave pattern to
establish the spacers as a woven mesh.
73. The adsorber element of claim 54, in which the
spacers are provided as a metal foil between
adjacent pairs of adsorbents sheets, with raised
folded or embossed ridges or grooves or perforations
in the foil so as to define flow channels contacting
the adsorbent material on the adjacent adsorbent
sheet on each side of the foil and extending in the
flow direction.
74. The adsorber element of claim 74, in which the metal
of the foil is aluminum.
75. The adsorber element of claim 74, in which the
adsorbent element stack is terminated by the
spacers, and the spacers at the terminating ends of
the adsorber element stack contact adsorbent
material only on the their inside side, with the
spacers at the terminating ends being configured to
present the same flow channel volume and flow


-52-

resistance as for spacers between a pair of
adsorbent sheets at intermediate positions within
the stack, so that all flow channels are thus
substantially identical in their contact with the
adsorbent material and in their hydraulic
characteristics.
76. The adsorber element of claim 56, in which the
adsorbent sheets are formed by coating the adsorbent
material on each side of an aluminum foil, except
for the adsorbent sheets at the terminating ends of
an adsorber element stack which are coated on one
side to be installed as the inside side only, so
that all flow channels contact the adsorbent
material on both sides, and are thus substantially
identical.
77. The adsorber element of claim 54, in which the
adsorbent material has macropores including
macropore channels orthogonal to the surface of the
adsorbent sheets contacting the flow channels and
substantially straight with minimal tortuosity.
78. The adsorber element of claim 77, in which the
macropore channels completely penetrate the
adsorbent sheets for favourable access from both
sides of the sheets.
79. The adsorber element of claim 54, in which the
composition of the adsorbent material is selected to
be different in each of multiple zones along the
flow path between the first and second ends.
80. The adsorber element of claim 79, applied to air
separation, and with at least two zones, a zone
closer to the first end having low silica X zeolite



-53-



exchanged with lithium ions, and a zone closer to
the second end having a zeolite selected from the
group of magnesium, calcium or strontium exchanged
chabazite or low silica zeolite X or zeolite A or
mordenite, for efficient removal of nitrogen from
lower concentrations.
81. The adsorber element of claim 76, also having a zone
adjacent the first end having an adsorbent selected
from the group of alumina gel, silica gel, and 13-X.
82. A rotary module for pressure swing adsorption
separation of a gas mixture containing components
which are respectively more readily adsorbed and
less relatively adsorbed component under pressure
increase over an adsorbent material; the rotary
module comprising a stator and a rotor with an axis
of rotation, the stator and rotor being mutually
engaged in fluid communication across a first rotary
valve surface and a second rotary valve surface both
centred on the axis of rotation; the stator having a
plurality of first function compartments each
opening into the first rotary valve surface in an
angular sector thereof, and a plurality of second
function compartments each opening into the second
rotary valve surface in an angular sector thereof;
the rotor having a plurality of angularly spaced
adsorber elements each having an angular width, and
with the adsorbent material supported on the walls
of parallel flow channels in the adsorber elements,
the flow channels being substantially identical to
each other, each such flow channel extending in a
flow direction between a first end communicating by
a first aperture to the first valve surface and a
second end communicating by a second aperture to the
second valve surface; and with means to rotate the



-54-



rotor such that each of the first apertures is
opened in fluid communication to the first function
compartments by rotation of the rotor bringing the
apertures sequentially into the angular sector of
each first function compartment, while each of the
second apertures is opened in fluid communication to
the second function compartments by rotation of the
rotor bringing the apertures sequentially into the
angular sector of each second function compartment
so as to achieve cycling of the pressure in each
adsorber element between an upper pressure and a
lower pressure; with means to provide the gas
mixture to a first function compartment at an upper
pressure, with means to exhaust gas enriched in a
more readily adsorbed component from a first
function compartment at a lower pressure, and with
means to deliver gas enriched in a less readily
adsorbed component from a second function
compartment at substantially the upper pressure; and
the rotary module further characterized in that the
function compartments also include a plurality of
pressurization compartments and blowdown
compartments for respectively subjecting the
adsorber elements to a plurality of incremental
pressure increases and a plurality of incremental
pressure decreases between the upper and lower
pressures and intermediate pressures therebetween.
83. The rotary module of claim 82, with multiple
angularly spaced adsorber elements undergoing each
of the said incremental pressure increases or
decreases, so that the flow and pressure at each of
the intermediate pressures is approximately steady.
84. The rotary module of claim 82, in which the
adsorbent material is supported on thin adsorbent


-55-

sheets, and the parallel flow channels are defined
by spacers between adjacent adsorbent sheets, with
the surfaces of the adsorbent sheets being walls of
the flow channels.

Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02274286 1999-06-09
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ROTARY PRESSDRS SWING ADSORPTION APPARATUS
FIELD OF THE INVENTION
The invention relates to gas separations
conducted by pressure swing adsorption, and in
particular applications to oxygen or nitrogen separation
from air and to hydrogen purification. A particular
application is for oxygen enrichment to mobile fuel cell
power plants, for which efficient and compact machinery
will be required.
BACKGROUND OF THE INVENTION
Gas separation by pressure swing adsorption
(PSA) is achieved by coordinated pressure cycling and
flow reversals over an adsorbent bed which
preferentially adsorbs a more readily adsorbed component
relative to a less readily adsorbed component of the
mixture. The total pressure is elevated during
intervals of flow in a first direction through the
adsorbent bed from a first end to a second end of the
bed, and is reduced during intervals of flow in the
reverse direction. As the cycle is repeated, the less
readily adsorbed component is concentrated in the first
direction, while the more readily adsorbed component is
concentrated in the reverse direction.
A "light" product, depleted in the more
readily adsorbed component and enriched in the less
readily adsorbed component, is then delivered from the
second end of the bed. A "heavy" product enriched in
the more strongly adsorbed component is exhausted from
the first end of the bed. The light product is usually
the desired product to be purified by PSA, and the heavy
product often a waste product, as in the important


CA 02274286 1999-06-09
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examples of oxygen separation over nitrogen-selective
zeolite adsorbents and hydrogen purification. The heavy
product is a desired product in the example of nitrogen
separation over nitrogen-selective zeolite adsorbents.
Typically, the feed is admitted to the first end of a
bed and the second product delivered from the second end
of the bed when the pressure in that bed is elevated to
a higher working pressure, while the second product is
exhausted from the first end of the bed at a lower
working pressure which is the low pressure of the cycle.
The conventional process for gas separation by
pressure swing adsorption uses two or more adsorbent
beds in parallel, with directional valuing at each end
of each adsorbent bed to connect the beds in alternating
sequence to pressure sources and sinks, thus
establishing the changes of working pressure and flow
direction. This conventional pressure swing adsorption
process makes inefficient use of applied energy, because
of irreversible expansion over the valves over large
pressure differences while switching the adsorbent beds
between higher and lower pressures.
Keefer (U.S. Pat. No. 5,256,172) discloses the
use of expansion turbines to recover power by the
principle of thermally coupled pressure swing
adsorption, in which expansion energy of the PSA cycle
is recovered and heat may be applied directly through an
integrated regenerative thermodynamic cycle
(regenerative Brayton cycle, or a modified Ericsson
cycle) as a supplemental energy source to perform
pressure swing adsorption gas separations.
Schartz (PCT publication WO 94/04249), Firey
(U. S. Pat. No. 4,530,705), and Watson et al (U. S. Pat.
No. 5,656,067) disclose the use of expanders for


CA 02274286 1999-06-09
- 3 -
partial recovery of energy from countercurrent blowdown
gas. In these prior art devices, the expanders,
compressors and vacuum pumps do not operate under steady
pressure conditions, since they withdraw gas from (or
supply gas to) one adsorbent bed at a time, while the
pressure in that adsorbent bed is changing as the gas
flow is withdrawn or supplied.
Siggelin (U. S. Patent No. 3,176,446), Mattia
(U. S. Patent No. 4,452,612), Davidson and Lywood (U. S.
Patent No. 4,758,253), Boudet et al (U.S. Patent No.
5,133,784), and Petit et al (U. S. Patent No. 5,441,559)
disclose PSA devices using rotary adsorbent bed
configurations. Ports for multiple angularly separated
adsorbent beds mounted on a rotor assembly sweep past
fixed ports for feed admission, product delivery and
pressure equalization; with the relative rotation of the
ports providing the function of a rotary distributor
valve. Related devices are disclosed by Kagimoto et al
(U. S. Patent No. 5,248,325) and LaCava et al (U. S.
Patent No. 5,487,775). All of these prior art devices
use multiple adsorbent beds operating sequentially on
the same cycle, with multiport distributor rotary valves
for controlling gas flows to, from and between the
adsorbent beds.
Parallel passage adsorbers are disclosed by
Keefer (U.S. Patent No. 4,702,903 ) and by Davidson and
Lywood (U. S. Patent No. 4,758,253). High surface area
laminated adsorbers, with the adsorbent supported in
thin sheets separated by spacers to define flow channels
between adjacent sheets, formed either as stacked
assemblies or as spiral rolls, have been disclosed by
Keefer (U.S. Patent No. 4,968,329 and U.S. Patent No.
5,082,473).


CA 02274286 1999-06-09
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The present invention is related to U.S.
Patent Application No. 08/995,906, which uses rotary
modules to provide an inherently simple valuing function
for connecting a large number of cooperating adsorber
elements sequentially to pressure sources and exhaust
sinks at multiple narrowly spaced pressure intervals.
Pressure and flow pulsations are preferably minimised by
using a large number of equally angularly spaced
adsorber elements in each module, while scale-up to the
largest capacity ratings may be achieved by combining
multiple rotary modules in parallel with a large
compressor with a single prime mover.
DISCLOSURE OF INVENTION
The present invention is intended to enable
high frequency operation of pressure swing and vacuum
swing adsorption processes, with high energy efficiency
and with compact machinery of low capital cost. The
invention applies in particular to air separation.
The invention provides an apparatus for PSA
separation of a gas mixture containing a more readily
adsorbed component and a less readily adsorbed
component, with the more readily adsorbed component
being preferentially adsorbed from the feed gas mixture
by an adsorbent material under increase of pressure, so
as to separate from the gas mixture a heavy product gas
enriched in the more readily adsorbed component, and a
light product gas enriched in the less readily adsorbed
component and depleted in the more readily adsorbed
component. The apparatus includes centrifugal
compression machinery cooperating with one or multiple
PSA modules in parallel. Each PSA module comprises a
plurality of adsorbers, with each adsorber having a flow


CA 02274286 1999-06-09
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path contacting adsorbent material between first and
second ends of the flow path.
Each PSA module further has a first valve
means cooperating with the adsorbers to admit feed gas
to the first ends of the adsorbers, and to exhaust heavy
product gas from the first ends of the adsorbers. Each
PSA module also has a second valve means cooperating
with the adsorbers to deliver light product gas from the
second ends of the adsorbers, to withdraw light reflux
gas from the second ends of the adsorbers, and to return
light reflux gas to the second ends of the adsorbers.
The term "light reflex" refers to withdrawal of light
gas (enriched in the less readily adsorbed component)
from the second ends of adsorbers via the second valve
means, followed by pressure let-down and return of that
light gas to other adsorbers at a lower pressure via the
second valve means. The first and second valve means
are operated so as to define the steps of a PSA cycle
performed sequentially in each of the adsorbers, while
controlling the timings of flow at specified total
pressure levels between the adsorbers and the
compression machinery.
The PSA process of the invention establishes
the PSA cycle in each adsorber, within which the total
working pressure in each adsorber is cycled between a
higher pressure and a lower pressure of the PSA cycle.
The PSA process also provides a plurality of
intermediate pressures between the higher and lower
pressure. The compression machinery of the apparatus in
general includes a feed gas centrifugal compressor and a
second product gas exhauster. The exhauster would be an
expander (e. g. radial inflow turbine) when the lower
pressure is at least atmospheric pressure. The exhauster
would be a vacuum pump when the lower pressure is


CA 02274286 1999-06-09
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subatmospheric. A light reflux gas expander may also be
provided for energy recovery from light reflux pressure
let-down, and may for example be used to drive a light
product compressor.
In the present invention, the feed compressor
will typically supply feed gas, in several stages at
discrete intermediate pressures for feed pressurization
of the adsorbers as well as the higher pressure for
light product production, to the first valve means. The
exhauster will typically receive second product gas, in
several stages at discrete intermediate pressures for
countercurrent blowdown of the adsorbers as well as the
lower pressure, from the first valve means. The light
reflux expander may also perform pressure let-down on
several separate light reflux stages, sequentially drawn
from the second valve means at a set of discrete
intermediate pressure levels, and after expansion
returned to the second valve means at a lower set of
discrete intermediate pressure levels. Heat exchangers
may be provided to heat gas streams about to be
expanded, for thermally boosted energy recovery.
In order for the flowing gas streams entering
or exiting the compression machinery at each pressure
level to be substantially uniform in pressure and
velocity, each PSA module will preferably have a
sufficiently large number of adsorbers for several
adsorbers to be undergoing each step of the PSA cycle at
any moment. During pressurization and blowdown steps,
the several adsorbers passing through the step would be
in sequentially phased converging approach to the
nominal pressure level of each step by a throttling
pressure equalization from the pressure level of the
previous step experienced by the adsorbers. Flow is
being provided to the adsorbers in a pressurization


CA 02274286 1999-06-09
step or withdrawn in a blowdown step by the compression
machinery at the nominal pressure level of that step.
Hence flow and pressure pulsations seen by the
compression machinery at each intermediate pressure
level are minimal by averaging from the several
adsorbers passing through the step, although each
adsorber undergoes large cyclic changes of pressure and
flow.
As set forth in copending U.S. Patent
Application No. 08/995,906, a preferred way to provide a
large number of adsorbers in a mechanically simple PSA
module is to install those adsorbers as angularly spaced
elements in a rotor, whose opposed faces engaging across
sealing faces with a ported stator sealing faces will
provide the first and second valve means. By providing
a sufficient number of ports with suitable angular
spacing to accommodate each of the desired pressure
levels (higher, lower and intermediate) in each of the
first and second valve faces, a desired PSA cycle can be
achieved.
If a smaller number of adsorbers is used in
each PSA module, surge absorber chambers will be needed
to isolate each stage of the compression machinery from
excessive pulsations of flow and pressure. With
sufficiently large surge absorber chambers, flow and
pressure pulsations seen by the compression machinery
are again minimized.
The architecture of adsorbers has three main
hierarchial levels to be addressed:
1) the micropores where selective adsorption
takes place within the adsorbent media


CA 02274286 1999-06-09
_ g _
2) the macropores providing access into the
adsorbent media at approximately micron scale
from the flow channels, and desirably with
minimal mass transfer resistance so that
departures from equilbrium between the
micropores and the adjacent flow channels are
always minimized,
3) the flow channels between bodies of adsorbent
media, and along which a concentration
gradient is established by the process.
In PSA gas separation using zeolite molecular
sieve adsorbents, the conventional art has established a
remarkable, precisely organized architecture at the
atomic scale by which the micropores are defined by the
zeolite crystal framework. The micropores are at
approximately manometer scale, and are organized up to
the typical scale of zeolite crystallites of one or a
few microns.
In conventional PSA technology, the zeolite
crystallites are agglomerated into an amorphous
macroporous structure to form adsorbent pellets or
beads. The macropores are provided by the more or less
random network of interconnecting cavities between the
crystallites, allowing for space taken up by the binder.
The resulting macropores will have a rather high
tortuosity factor, multiplying the effective length of
the macropores by a factor of typically three to
increase mass transfer diffusional resistance
correspondingly.
The adsorbent beads are typically formed at
the scale of one or a few millimeters, and are loaded
into the adsorber containment vessel to form a packed


CA 02274286 1999-06-09
_ g _
bed. The flow channels are provided by the voidage
fraction between the beads, and typically have a length
of the order of one meter. The random assembly of the
packed bed, along with mixing events as the flow splits
and recombines around the beads, results in axial
dispersion which degrades the sharpness of the
concentration wavefront established by the separation
process. The packed bed also has inherently high
pressure drop in the flow channels.
While prior art adsorbent beds based on
zeolite molecular sieves are ideally organized at the
micropore scale of the zeolite crystal lattice, their
architecture is far from satisfactory at the scale of
the macropores (bead architecture) and the flow channels
(adsorber architecture). Packed beds of granular beads
are subject to pressure drop and fluidization
constraints which make it impracticable to operate with
small diameter beads, much smaller than 1 millimeter
diameter. The mass transfer macropore diffusional
resistance of relatively large beads, further
exacerbated by the macropore tortuosity factor, preclude
efficient sustained operation at PSA cycle frequencies
greater than approximately 10 cycles per minute.
Previous investigations by Reefer (U. S. Patent
No. 4,968,329 and U.S. Patent No. 5,082,473) have
established a much improved architecture of the
adsorbent media bodies and the flow channels, in which
the adsorbent is supported in the form of "adsorbent
sheets". The adsorbent sheets are thin sheets (either
as the adsorbent with a composite reinforcement, or as
an inert sheet or foil coated with the adsorbent), with
the flow channels established by spacers as parallel
channels between adjacent pairs of sheets. This
"adsorbent laminate" configuration has much lower


CA 02274286 1999-06-09
- 10 -
pressure drop than packed beds, and avoids the
fluidization problem of packed beds. In experimental
adsorbers tested to date, the adsorbent sheets are in
the range of 100 to 175 microns thick. The channel
width between adjacent adsorbent sheets of the
experimental adsorbers has been in the range of 50~ to
100 of the adsorbent sheet thickness.
Intermediate between the microscale of the
zeolite crystallites and the macroscale of the laminate,
the mesoscale architecture of the macropore network
remains a challenge to be organized. The challenge is
to improve on the highly tortuous macropore network
provided by the amorphous structure of zeolite
crystallites cemented together by conventional binders.
Typical tortuosity factors in zeolite adsorbent pellets
are in the order of 3 to 4. Straightening the
macropores into a parallel bundle of straight pores
orthogonal to the external surface of the adsorbent
sheet would ideally result in a tortuosity factor of 1,
greatly reducing macropore diffusional resistance which
usually controls mass transfer. As the macropore
diffusional time constant is proportional to the
tortuosity factor and inversely proportional to the
adsorbent characteristic dimension (pellet diameter or
laminate adsorbent sheet thickness), a factor of 4
reduction in tortuosity is equivalent to a factor of 2
reduction in the characteristic dimension. Hence, for
equal macropore mass transfer resistance at the same
cycle frequency, the adsorbent characteristic dimension
may be increased to reduce adsorbent flow channel
surface area and consequently adsorbent manufacturing
cost, and also to reduce pressure drop in the flow
channels. Alternatively, the characteristic dimension
may be held the same, and the reduced tortuosity and
reduced macropore resistance may then be exploited to


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increase cycle frequency. This reduces the volume of the
adsorbent, and again reduces the installed cost of the
adsorbent.
Accordingly, an important aspect of the
invention is alignment of macropore channels for
improved high frequency PSA adsorbers.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a simplified schematic of a PSA
apparatus, and Fig. 2 shows a typical PSA cycle, in the
format to which the invention shall be applied.
Fig. 3 shows a radial flow rotary module for
VPSA oxygen production with a compressor and a vacuum
pump exhauster.
Figs. 4, 5, 6 and 7 show an axial flow rotary
module for PSA oxygen production.
Fig. 8 shows an alternative rotor with curved
adsorbers.
Fig. 9 shows the radial flow rotor of Fig. 3,
with the adsorbers as angular sectors.
Figs. 10 and 11 show a laminated sector
adsorber for the rotor of Fig. 9, with the adsorbent
sheets normal to the axis of the rotor.
Fig. 12 is a section of the rotor of Fig. 9,
using the adsorbers of Fig. 10.


CA 02274286 1999-06-09
- 12 -
Fig. 13 shows an alternative laminated sector
adsorber for the rotor of Fig. 9, with the adsorbent
sheets parallel to the axis of the rotor.
Figs. 14 and 15 show an alternative radial
flow adsorber wheel configuration, with the adsorbent
sheets provided as annular discs.
Figs. 16 and 17 show details of adsorbent
laminate spacer configurations.
Fig. 18 shows layering of the adsorbents
selected between the first and second ends of the
adsorbers.
Fig. 19 and 20 show alternative spiral wrapped
axial flow laminate adsorbers.
Figs. 21, 22 and 23 show alternative spacers.
Fig. 24 shows an alternative laminated sector
adsorber for the rotor of Fig. 9, with the adsorbent
sheets parallel to the axis of the rotor, and with
radial tapering provided by interspersing adsorbent
sheets of differing width in the radial direction.
Fig. 25 shows a detail of adsorbent sheets
assembled from zeolite-coated strips of aluminum foil,
stacked so as to define macropore channels between
adjacent strips, the said macropore channels being
substantially straight and orthogonal to the surface of
the adsorbent sheet contacting the main flow channels.
MODES FOR CARRYING OUT THE INVENTION
Figs. 1 and 2


CA 02274286 1999-06-09
- 13 -
Fig. 1 shows an elementary PSA apparatus 1
with an adsorber assembly 2 having a plurality of "N"
cooperating adsorbers 3 in parallel. Each adsorber has
a flow path 4 between first end 5 and second end 6 of
the adsorber 3, with adsorbent material contacting the
flow path. Cooperating with the adsorbers are first
valve means 7 and second valve means 8. Arrow 9
indicates the direction of progression of the adsorbers
in being connected to ports of the first and second
valve means as shown in Fig. 1. In the case of a
rotary adsorber, as in the preferred embodiments of the
invention, adsorber rotor 2 is shown in Fig. 1 unrolled
in a 360° section about its rotary axis so that rotation
causes the adsorbers to advance in the direction of
arrow 9 to undergo the cycle of Fig. 2.
The left hand edge 13 of the unrolled view of
rotor 2 returns to right hand edge 14 after rotation of
360°. It is also possible within the invention to have
an integral multiple of "M" groups of "N" adsorbers in a
single rotor 2, so that the angular extent for edge 13
to edge 14 is 360°/M. This has the disadvantage of
greater complexity of fluid connections to the first and
second valve means, but the advantages of slower
rotational speed (by a factor of "M" for the same PSA
cycle frequency) and a symmetric pressure and stress
distribution. With "M" - 2, Fig. 1 represents each 360°
side of a rotor according to the invention.
Fig. 2 shows the PSA cycle undergone
sequentially by each of the "N" adsorbers 3 over a cycle
period "T". The cycle in consecutive adsorbers is
displaced in phase by a time interval of T/N. In Fig. 2
the vertical axis 10 indicates the working pressure in
the adsorbers and the pressures in the first and second
compartments. Pressure drops due to flow within the


CA 02274286 1999-06-09
- 14 -
adsorber elements are here neglected. The higher and
lower working pressures of the PSA process are
respectively indicated by dotted lines 11 and 12.
The horizontal axis 15 indicates time, with
the PSA cycle period defined by the time interval
between points 16 and 17. At times 16 and 17, the
working pressure in adsorber 3 is pressure 18. Starting
from time 16, the cycle begins as the first end 5 of
adsorber 3 is opened by the first valve means 7 to first
feed supply means 20 at the first intermediate feed
pressure 21. The pressure in that adsorber rises from
pressure 18 at time 17 to the first intermediate feed
pressure 21. Proceeding ahead, the first end 5 is
opened next to second feed supply means 22 at the second
intermediate feed pressure 23. The adsorber pressure
rises to the second intermediate feed pressure.
Then the first end 5 is opened to a third feed
supply means 24 at the higher pressure of the PSA
process. Once the adsorber pressure has risen to
substantially the higher working pressure, its second
end 6 is opened by the second valve means to light
product delivery conduit 25 to deliver purified light
product. While feed gas is still being supplied to the
first end of adsorber 3 from the third feed supply
means, the second end 6 is next closed to light product
delivery conduit 25, arid is opened to deliver "light
reflux" gas (enriched in the less readily adsorbed
component, similar to second product gas) by conduit 29
to first light reflux pressure let-down means 30. The
light reflux pressure let-down means may be an expander
with optional heat exchangers such as an inlet heater,
or a throttle orifice. All or some of the feed supply
means may be feed compression stages. One of the feed
supply means may be an external source, such as the


CA 02274286 1999-06-09
- 15 -
ambient atmosphere for air purification or air
separation applications.
The first end 5 of adsorber 3 is then closed
by the first valve means, while the second end 6 is
opened successively by the second valve means to (a)
drop the adsorber pressure to the first cocurrent
blowdown pressure 32 while delivering light reflex gas
by conduit 33 to second light reflex pressure letdown
means 34, (b) drop the adsorber pressure to the second
cocurrent blowdown pressure 36 while delivering light
reflex gas by conduit 37 to third light reflex pressure
letdown means 38, and (c) drop the adsorber pressure to
the third cocurrent blowdown pressure 40 while
delivering light reflex gas by conduit 41 to fourth
light reflex pressure letdown means 42. Second end 6 is
then closed for an interval, until the light reflex
return steps following the countercurrent blowdown
steps.
The light reflex pressure let-down means may
be mechanical expansion stages for expansion energy
recovery, or may be restrictor orifices or throttle
valves for irreversible pressure let-down.
Either when the second end 6 is closed after
the final light reflex exit step (as shown in Fig. 2),
or earlier while light reflex exit steps are still
underway, first end 5 is opened to first exhaust means
46, dropping the adsorber pressure to the first
countercurrent blowdown intermediate pressure 48 while
releasing "heavy" gas (enriched in the more strongly
adsorbed component) to the first exhaust means. Next,
first end 5 is opened to second exhaust means 50,
dropping the adsorber pressure to the second
countercurrent blowdown intermediate pressure 52 while


CA 02274286 1999-06-09
- 16 -
releasing "heavy" gas. Then first end 5 is opened to
third exhaust means 54, dropping the adsorber pressure
to the lower pressure 12 of the PSA process while
releasing "heavy" gas. Once the adsorber pressure has
substantially reached the lower pressure while first end
5 is open to the third exhaust means 54, the second end
6 is opened to receive fourth light reflux gas (as purge
gas) from fourth light reflux pressure let-down means 42
by conduit 55 in order to displace more heavy gas into
the third exhaust means. The heavy gas from the first,
second and third exhaust means may be delivered together
as the heavy product 56. All or some of the exhaust
means may be mechanical exhauster stages, alternatively
either expansion stages if the pressure is to be
reduced, or vacuum pumping stages if the pressure is to
be increased to ambient pressure, or exhaust compression
stages if the exhaust of second product is to be
delivered at an elevated pressure. An exhaust means may
also be provided by venting to an external sink, e.g.
the ambient atmosphere.
The adsorber is then repressurized by light
reflux gas after the first end 5 is closed. In
succession, the second end 6 is opened (a) to receive
light reflux gas by conduit 59 from the third light
reflux pressure letdown means 38 to raise the adsorber
pressure to the first light reflux pressurization
pressure 60, (b) to receive light reflux gas by conduit
61 from the second light reflux pressure letdown means
34 to raise the adsorber pressure to the second light
reflux pressurization pressure 62, and (c) to receive
light reflux gas by conduit 63 from the first light
reflux pressure letdown means 30 to raise the adsorber
pressure to the third light reflux pressurization
pressure. Unless feed pressurization has already been
started while light reflux return for light reflux


CA 02274286 1999-06-09
- 17 -
pressurization is still underway, the process begins
feed pressurization for the next cycle after time 17 as
soon as the third light reflex pressurization step has
been concluded.
From each feed supply means (e.g. 20), the
feed flow is delivered by a conduit 70 through an
optional surge absorber chamber 71 to a feed compartment
72 opening to a feed port 73 in first valve means 7.
Feed compartment 72 may be open to several adsorbers
simultaneously, and may have a restricted entrance 74 so
as to provide a gradual throttling equalization of
pressure as each adsorber is opened to feed compartment
72.
To each exhaust means (e. g. 46), the exhaust
flow is delivered by a conduit 80 through an optional
surge absorber chamber 81 from an exhaust compartment 82
opening to an exhaust port 83 in first valve means 7.
Exhaust compartment 82 may be open to several adsorbers
simultaneously, and may have a restricted entrance 84 so
as to provide a gradual throttling equalization of
pressure as each adsorber is opened to exhaust
compartment 82.
To light product delivery conduit 25, the
light product is delivered through an optional surge
absorber chamber 86 from light product exit compartment
87 opening to a light product port 88 in second valve
means 8.
To each light reflex pressure letdown means
(e.g. 34), the light reflex flow is delivered by a
conduit 90 through an optional surge absorber chamber 91
from a light reflex exit compartment 92 opening to a
light reflex exit port 93 in second valve means 8.


CA 02274286 1999-06-09
- 18 -
Light reflex exit compartment 92 may be open to several
adsorbers simultaneously, and may have a restricted
entrance 94 so as to provide a gradual throttling
equalization of pressure as each adsorber is opened to
light reflex exit compartment 92.
From each light reflex pressure letdown means
(e.g. 34), the light reflex flow is delivered by a
conduit 95 through an optional surge absorber chamber 96
to a light reflex entrance compartment 97 opening to a
light reflex entrance port 98 in second valve means 8.
Light reflex exit compartment 97 may be open to several
adsorbers simultaneously, and may have a restricted
entrance 99 so as to provide a gradual throttling
equalization of pressure as each adsorber is opened to
light reflex entrance compartment 97.
The rate of pressure change in each
pressurization or blowdown step may thus be restricted
by throttling in compartments of the first and second
valve means, or by throttling in the ports at first and
second ends of the adsorbers, resulting in the typical
pressure waveform depicted in Fig. 2. Excessively rapid
rates of pressure change would subject the adsorber to
mechanical stress, while also causing flow transients
which would tend to increase axial dispersion of the
concentration wavefront in the adsorber. Pulsations of
flow and pressure are minimized by having a plurality of
adsorbers simultaneously transiting each step of the
cycle, and/or by providing surge absorbers in the
conduits connecting to the first and second valve means.
It will be evident that the cycle shown in
Fig. 2 could be generalized by having more or fewer
intermediate stages in each major step of feed
pressurization, countercurrent blowdown exhaust, or


CA 02274286 1999-06-09
- 19 -
light reflux. Furthermore, in air separation or air
purification applications, a stage of feed
pressurization (typically the first stage) could be
performed by equalization with atmosphere as an
intermediate pressure of the cycle. Similarly, a stage
of countercurrent blowdown could be performed by
equalization with atmosphere as an intermediate pressure
of the cycle.
Figs-3
Fig 3 shows a simplified schematic of a VPSA
(vacuum pressure swing adsorption) air separation system
100, with a multistage or split stream centrifugal
compressor 101 and a multistage or split stream exhaust
vacuum pump 102. The rotary adsorber module 103
includes adsorber rotor 2, and a stator assembly
comprising a first valve stator 104 and a second valve
stator 105. Rotor 2 may be configured for radial flow
as suggested in Fig. 3, or for axial flow.
Rotor 2 contains the "N" adsorbers 3, with the
flow path here oriented radially between first end 5 and
second end 6 of the adsorbers. The adsorber first ends
5 open by apertures 106 to a sealing face 107 with the
first valve stator 108, which has ports 109 to define
the first valve means 7. First valve stator 108 has a
plurality of functional compartments in fluid
communication to sealing face 107 by ports 109,
including a first feed pressurization supply compartment
111, a second first feed pressurization supply
compartment 112, a feed production supply compartment
113 at substantially the higher pressure, a first
countercurrent blowdown exhaust compartment 114, a
second countercurrent blowdown exhaust compartment 115,


CA 02274286 1999-06-09
- 20 -
and a purge exhaust compartment 116 at substantially the
lower pressure.
The adsorber second ends 6 open by apertures
118 to a sealing face 119 with the second valve stator
105 which has ports 120 to define the second valve means
8. Second valve stator 105 includes, with each
compartment in fluid communication to sealing face 119
by ports 120, a light product delivery compartment 121
at substantially the higher pressure, a first light
reflex exit compartment 122 which is here simply the
downstream end of compartment 121, a second light reflex
exit compartment 123, a third light reflex exit
compartment 124, a fourth light reflex exit compartment
125, a fourth light reflex return compartment 126 for
purge at substantially the lower pressure, a third light
reflex return compartment 127, a second light reflex
return compartment 128, and a first light reflex return
compartment 129. The angular spacing of ports
communicating to the compartments in the first and
second valve stators defines the timing of the PSA cycle
steps similar to the cycle of Fig. 2.
In this example, sealing faces 107 and 119 are
respectively defined by the outer and inner radii of the
annular rotor 2. Fluid sealing between the functional
compartments in sealing face is achieved by clearance
seals. The clearance seals are provided as slippers 130
attached to the first and second valve stators by
partitions 131. Partitions 131 provide static sealing
between adjacent compartments. Slippers 130 engage the
sealing faces with narrow fluid sealing clearances,
which also provide throttling of gas flows between the
adsorbers and functional compartments in each pressure-
changing step, so that each adsorber may smoothly
equalize in pressure to the pressure of the next


CA 02274286 1999-06-09
- 21 -
functional compartment about to be opened to that
adsorber. In addition to the functional compartments,
static pressure balancing compartments (e.g. 132 and
133) are provided behind some clearance seal slippers.
The static pressure balancing compartments are disposed
in angular sectors of the first and second valve stators
not used as functional compartments, in order to
establish a controlled pressure distribution behind the
clearance slippers so as to maintain their positive
sealing engagement without excessive contact pressure
and consequent friction.
Apparatus 100 has a feed air inlet filter 140,
from which feed air is conveyed through optional
dehumidifier 141 and conduit 142 to feed compressor
inlet 143. In this example, the first intermediate
feed pressurization pressure is selected to be
substantially atmospheric pressure, so conduit 142 also
communicates to first feed pressurization compartment
111. The feed compressor 101 has a first discharge port
144 at the second intermediate feed pressurization
pressure communicating by conduit 145 and optional
dehumidifier 146 to compartment 112, and a second
discharge port 147 at substantially the higher pressure
of the cycle pressure communicating by conduit 148 and
optional dehumidifier 149 to compartment 213.
Exhaust vacuum pump 102 has a first inlet port
150 at substantially the lower pressure of the cycle in
fluid communication with exhaust compartment 116, a
second inlet port 152 at the second countercurrent
blowdown pressure in fluid communication with
compartment 115, and a third inlet port 154 at the first
countercurrent blowdown pressure in fluid communication
with compartment 114. Vacuum pump 102 compresses the
combined exhaust and countercurrent blowdown gas as the


CA 02274286 1999-06-09
- 22 -
second product gas enriched in the more readily adsorbed
component to substantially atmospheric pressure, and
discharges the second product gas from discharge port
156.
In the option of light reflux pressure let-
down without energy recovery, throttle valves 160
provide pressure let-down for each of four light reflux
stages, respectively between light reflux exit and
return compartments 122 and 129, 123 and 128, 124 and
127, and 125 and 126 as illustrated. Actuator means 165
is provided to adjust the orifices of the throttle
valves.
Fig~s.4, 5, 6 and 7
Fig. 4 shows an axial flow rotary PSA module
200, particularly suitable for smaller scale oxygen
generation. The flow path in adsorbers 3 is now
parallel to axis 201. The steps of the process and
functional compartments are still in the same angular
relationship regardless of a radial or axial flow
direction in the adsorbers. Figs. 5, 6 and 7 are cross
sections of module 200 in the planes respectively
defined by arrows 202 - 203, 204 - 205, and 206 - 207.
Fig. 4 is an axial section of module 200 through
compartments 113 and 121 at the higher pressure, and
compartments 126 and 117 at the lower pressure. The
adsorber rotor 2 contains the "N" adsorbers 3 in
adsorber wheel 208, and revolves between the first valve
stator 103 and the second valve stator 105. Compressed
feed air is supplied to compartment 113 as indicated by
arrow 211, while nitrogen enriched exhaust gas is
exhausted from compartment 117 as indicated by arrow
212.


CA 02274286 1999-06-09
- 23 -
At the ends of rotor 2, circumferential seals
215 and 216 bound first sealing face 107, and
circumferential seals 217 and 218 bound second sealing
face 119. The sealing faces are flat discs. The
circumferential seals also define the ends of clearance
slippers 130 in the sealing faces between the functional
compartments. Rotor 2 is supported by bearing 220 in
housing 225, which is integrally assembled with the
first and second valve stators. Rotor 2 is driven by rim
drive motor 230, which may have a friction, geared or
belt engagement with the outer rim of rotor 2.
Illustrating the option of light reflex
pressure letdown with energy recovery, a split stream
light reflex expander 240 is provided to provide
pressure let-down of four light reflex stages with
energy recovery. The light reflex expander provides
pressure let-down for each of four light reflex stages,
respectively between light reflex exit and return
compartments 122 and 129, 123 and 128, 124 and 127, and
125 and 126 as illustrated.
Light reflex expander 240 is coupled to a
light product pressure booster compressor 245 by drive
shaft 246. Compressor 245 receives the light product
from conduit 25, and delivers light product (compressed
to a delivery pressure above the higher pressure of the
PSA cycle) to delivery conduit 250. Since the light
reflex and light product are both enriched oxygen
streams of approximately the same purity, expander 240
and light product compressor 245 may be hermetically
enclosed in a single housing. This configuration of a
"turbocompressor" oxygen booster Without a separate
drive motor is advantageous, as a useful pressure boost
of the product oxygen can be achieved without an
external motor and corresponding shaft seals, and can


CA 02274286 1999-06-09
- 24 -
also be very compact when designed to operate at very
high shaft speeds.
Fig. 5 shows the first valve face of
embodiment 200 of Fig. 3, at section 202 a 203, with
fluid connections to a multistage or split stream feed
compressor 101 and to a multistage or split stream
countercurrent blowdown expander 260 as in Fig. 4.
Arrow 270 indicates the direction of rotation
by adsorber rotor 2. The open area of valve face 107
ported to the feed and exhaust compartments is indicated
by clear angular segments 111 a 217 corresponding to
those functional compartments, between circumferential
seals 215 and 216. The substantially closed area of
valve face 107 between functional compartments is
indicated by cross-hatched sectors 275 and 276 which are
clearance slippers 130. Typical closed sector 275
provides a transition for an adsorber, between being
open to compartment 114 and open to compartment 115.
Gradual opening is provided by a tapering clearance
channel between the slipper and the sealing face, so as
to achieve gentle pressure equalization of an adsorber
being opened to a new compartment. Much wider closed
sectors (e. g. 276) are provided to substantially close
flow to or from one end of the adsorbers when
pressurization or blowdown is being performed from the
other end.
Fig. 6 shows the second valve face of
embodiment 200 of Fig. 3, at section 204 a 205, with
fluid connections to a split stream light reflux
expander 240 and light product booster compressor 245 as
in Fig. 5. Fluid sealing principles and alternatives
are similar to those of Fig. 5. Similar principles and
alternatives apply to radial flow and axial flow


CA 02274286 1999-06-09
- 25 -
geometries, respectively sealing on cylindrical or disc
faces .
Fig. 7 shows an adsorber wheel configuration
for the embodiment of Fig. 3, at section 206 - 207. The
adsorber configuration of Fig. 7 is similar to a radial
flow geometry shown in copending U.S. Patent Application
No. 08/995,906. Here, "N" - 72. The adsorbers 3 are
mounted between outer wall 280 and inner wall 281 of
adsorber wheel 208. Each adsorber comprises a
rectangular flat pack of adsorbent sheets 282, with
spacers 283 between the sheets to define flow channels
here in the axial direction. Separators 284 are
provided between the adsorbers to fill void space and
prevent leakage between the adsorbers.
The adsorbent sheets comprise a reinforcement
material, in preferred embodiments glass fibre, metal
foil or wire mesh, to which the adsorbent material is
attached with a suitable binder. For air separation to
produce enriched oxygen, typical adsorbents are X, A or
chabazite type zeolites, typically exchanged with
lithium, calcium, strontium, magnesium and/or other
cations, and with optimized silicon/aluminum ratios as
well known in the art. The zeolite crystals are bound
with silica, clay and other binders, or self-bound,
within the adsorbent sheet matrix.
Satisfactory adsorbent sheets have been made
by coating a slurry of zeolite crystals with binder
constituents onto the reinforcement material, with
successful examples including nonwoven fiber glass
scrims, woven metal fabrics, and expanded aluminum
foils. Spacers are provided by printing or embossing
the adsorbent sheet with a raised pattern, or by placing
a fabricated spacer between adjacent pairs of adsorbent


CA 02274286 1999-06-09
- 26 -
sheets. Alternative satisfactory spacers have been
provided as woven metal screens, non-woven fiber glass
scrims, and metal foils with etched flow channels in a
photolithographic pattern.
Typical experimental sheet thicknesses have
been 150 microns, with spacer heights in the range of
100 to 150 microns, and adsorber flow channel length
approximately 20 cm. Using X type zeolites, excellent
performance has been achieved in oxygen separation from
air at PSA cycle frequencies in the range of 30 to 150
cycles per minute.
FiQ.8
Fig.8 shows an alternative configuration of
rotor 208, in which the adsorbers 3 are again formed of
a pack of rectangular adsorbent sheets with spacers, but
with the sheets here curved to circular arcs rather than
flat. Voids between the circularly curved adsorber
packs are filled by separators 484. Such circularly
curved adsorber packs may be made by forming the
adsorbent sheets with spacers in a spiral roll on a
circular cylindrical mandrel, and then slitting the
spiral roll longitudinally to obtain the desired packs.
Packing density could be further improved by forming the
adsorber packs to a spiral rather than circular curve,
for example by a pleating technique, or by
longitudinally cutting a spiral roll formed on a
noncircular mandrel whose shape in two to four identical
angular sectors defines the desired spiral.
Fig. 9
Fig. 9 shows an enlarged view of the radial
flow rotor 2 of Fig. 3. The adsorbers 3 are contained


CA 02274286 1999-06-09
- 27 -
in trapezoidal angular sectors between radial partitions
301. Partitions 301 are attached to outer rotor shell
303 and inner rotor shell 304. Outer shell 303 engages
sealing face 107 and is perforated with apertures 106
communicating with the first ends 5 of adsorbers 3.
Inner shell 304 engages sealing face 119 and is
perforated with apertures 118 communicating with the
second ends 6 of adsorbers 3. An important advantage
of this geometry is the tapering of the adsorbers from
the first to second ends of the flow path, thus reducing
feed flow velocity and pressure drop adjacent the first
end 5.
Figs . 10 - 12
Figs. 10 and 11 show a laminated sector
adsorber for the rotor of Fig. 9, with the adsorbent
sheets normal to the axis of the rotor. The flat
adsorbent sheets 310 are separated by spacers 311 to
define flow channels 312 between first end 5 and second
end 6. Sheets 310 are on edges 320 to fit the
trapezoidal shape of adsorbers 3 between partitions 301.
In Fig. 11, radial spacers 325 define radially tapered
channels 312. Spacers 325 may be printed onto the
adsorbent sheets, and may have the structure shown in
Fig. 16. Alternative spacer geometries based on Figs.
17 or 21 a 23 may also be adapted by tapering to the
radial flow pattern required by the trapezoidal shape.
Fig. 12 shows an axial section of the radial flow rotor
of Fig. 9, with the sector adsorber of Fig. 10.
Fig. 13
Fig. 13 shows an alternative laminated sector
adsorber for the rotor of Fig. 9, with the adsorbent
sheets in radial planes parallel to the axis of the


CA 02274286 1999-06-09
- 28 -
rotor. Rectangular adsorbent sheets 341 and/or the
spacers defining channels 342 are tapered so that the
combination of an adsorbent sheet and the adjacent
channel has a constant angular width.
Figs. 14 and 15
Figs. 14 and 15 show an alternative radial
flow adsorber wheel configuration, with the adsorbent
sheets provided as complete annular discs. As in Fig.
11, radial spacers 325 define flow channels 312. The
spacers of Fig. 15 substantially prevent transverse flow
between adjacent channels, which thus each define very
narrow adsorbers.
Figs. 16 and 17
Figs. 16 and 17 show details of adsorbent
laminate spacer configurations. In Fig. 16, spacer
ridges 331 are formed by calendaring or by printing one
of both sides of adsorbent sheets 310. Preferably,
spacers 331 are aligned between adjacent sheets so as to
provide compressive strength and stability.
In Fig. 17, the adsorbent is applied as
coating layers 360 to both sides of a support aluminum
foil 361 whose surface has been anodized for good
adhesion. Spacers 362 are printed or embossed on the
coated foil.
Fic~. 18
Fig. 18 shows layering of the adsorbents
selected between the first and second ends of the
adsorbers in a radial flow configuration. Similar
axial layering may be applied to axial flow embodiments


CA 02274286 1999-06-09
- 29 -
of the invention. From first end 5 to second end 6 of
the adsorbers, the flow path passes through first zone
401, second zone 402 and third zone 403 of the
adsorbent. The first zone adsorbent may be alumina gel,
silica gel or 13-X zeolite for water vapour removal.
For air separation, the second zone adsorbent
may be highly lithium exchanged low silica X zeolite for
most efficient bulk nitrogen removal. The third zone
adsorbent may advantageously be magnesium, calcium or
strontium exchanged chabazite or low silica zeolite X or
zeolite A, for most efficient removal of nitrogen from
lower concentrations.
For hydrogen separation from syngas, the
second zone adsorbent may be 13-X zeolite for efficient
bulk carbon dioxide removal. The third zone adsorbent
may advantageously be calcium or strontium exchanged
chabazite or low silica X zeolite, for efficient removal
of carbon monoxide and any nitrogen.
The zones of different adsorbent composition
between the first and second ends of the adsorbent
elements may be provided by coating the adsorbent sheets
in bands of different composition prior to assembly of
the elements, or by assembling the elements from
separate sheets of the respective compositions so that
the gas flowing along the flow path encounters different
sheets coated with the respective composition between
the first and second ends.
Figs. 19 and 20
Figs. 19 and 20 show alternative spiral
wrapped axial flow laminate adsorbers. The Fig. 19
configuration of a spiral wound adsorber wheel with one


CA 02274286 1999-06-09
- 30 -
or a few laminate sheets rolled around hub 411 is
suitable for axial flow only. The Fig. 20 configuration
of a steep spiral roll of a very large number of leaves
may in principle be used for either axial or radial
embodiments. Each of these geometries may use spacers
such as those of Fig. 16 to isolate the flow channels
against transverse flow, so that each flow channel is an
independent adsorber.
Figs. 21, 22 and 23
Figs. 21, 22 and 23 show alternative spacers
for use in adsorbers or adsorber sections not requiring
compartmentalization against transverse flow, for
example the embodiments of Figs. 7, 8 and 13. The
direction of flow is defined by arrow 501. In Fig. 21,
raised spacers 505 are applied by printing. In Figs. 22
and 23, woven spacers of wire screen are used. The mesh
of Fig. 23 is a Dutch weave, with fine stabilizing wires
531 and 532 criss-crossing heavier longitudinal spacer
wires 533 in the flow direction. Some or all of the
stabilizing wires may be replaced by polymer fibres
which are burnt out during adsorbent activation.
Fig. 24
Fig. 24 shows a angularly narrow portion of an
alternative laminated sector adsorber for the rotor of
Fig. 9, with a group of adsorbent sheets parallel to the
axis of the rotor, and with radial tapering provided by
interspersing adsorbent sheets of differing width in the
radial direction. Adsorbent sheets 601, 602, 603, 604,
605 and 606 have printed spacers 610 between adjacent
pairs of the sheets, to establish flow channels in the
radial direction between first end 5 and second end 6.
Spacers 610 are printed in a pattern such as that shown


CA 02274286 1999-06-09
- 31 -
in Fig. 21. Vrhile some of the adsorbent sheets (601,
602, 603 and 604) extend the entire radial distance
between the first and second ends, others (605 and 606)
extend from the first end 5 only varying fractions of
the radial distance to the second end 6. Thus, sheet
606 has only approximately a third of the radially
extending width, and sheet 605 two thirds of the
radially extending width, as the other sheets 601 a 604.
Since the stack of adsorbent sheets is thicker at the
first end than at the second, it can be tapered by
appropriately selecting the fraction of sheets to have
reduced radial widths, so as to have an approximately
constant angular width between the first and second
ends.
In this embodiment, the sheets are flexible so
as to flex around the terminations 611 and 612 of sheets
606 and 605, so as to minimize disturbances of flow
distribution and channel pressure resistance adjacent
the sheet terminations.
Fig.25
Fig. 25 shows a detail portion of two adjacent
adsorbent sheets 701 and 702 assembled from zeolite-
coated strips of aluminum foil, stacked so as to define
macropore channels between adjacent strips, the said
macropore channels being substantially straight and
orthogonal to the surface of the adsorbent sheet
contacting the main flow channels.
An adsorbent sheet (e. g. 100 to 250 microns
thick) 701 may be assembled from strips 703 of aluminum
foil of approximately 12 microns thickness (equivalent
to cigarette wrapper foil). The foil is slit into
strips whose width is nominally equal to the final


CA 02274286 1999-06-09
- 32 -
thickness of the sheet. The strips are preferably
anodized for good adhesion of zeolite, and are coated on
each side with a coating layer 704 or film of zeolite
crystals approximately 4 to 6 microns thick. The
zeolite crystals may be grown in situ from a zeolite
synthesis solution, as with the known art of depositing
crystalline zeolite films for membranes, although here
there is no concern about avoiding minor crevices or
pinholes through the zeolite film. Alternatively, the
zeolite coatings may be formed by conversion of a
metakaolin coating applied to the foil. Alternatively,
the zeolite crystals may be formed separately, and then
attached by binders (e.g. clay or silica) to the
anodized sheet. The strips are then stacked on each
other, with their edges in contact with parallel
longitudinal support members 706 for sheet 701 and
members 707 for sheet 702, orthogonal to the strips so
as to form the adsorbent sheets, constituted by the
stacked strips being retained by the parallel
longitudinal support members to retain the strips and
provide structural integrity. The adsorbent sheets
are then stacked to form a parallel passage adsorber,
with the parallel longitudinal support members serving
as spacers members defining flow channels with flow
direction indicated by arrows 708 and 709, orthogonal to
the strips and between adjacent pairs of adsorbent
sheets. Between each pair of adsorbent sheets 701 and
702, the parallel longitudinal support members 706 are
separated tranversely so as provide open flow channels,
while providing support to the zeolite coated strips 704
constituting each sheet.
The zeolite crystal coating on the aluminum
strips will have a granular surface texture, so that
sufficient voidage will exist between the contacting
zeolite surfaces of adjacent coated strips to provide


CA 02274286 1999-06-09
- 33 -
direct fluid access from the flow channels. This
voidage between zeolite films of adjacent strips serves
as primary macropore channels, which are substantially
straight with minimal tortuosity, and are orthogonal to
the surface of the adsorbent sheets contacting the flow
channels.
while only preferred embodiments of the
invention have been described herein in detail, the
invention is not limited thereby and modifications can
be made within the scope of the attached claims.

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date Unavailable
(22) Filed 1999-06-09
(41) Open to Public Inspection 2000-12-09
Examination Requested 2004-04-30
Dead Application 2006-06-09

Abandonment History

Abandonment Date Reason Reinstatement Date
2005-06-09 FAILURE TO PAY APPLICATION MAINTENANCE FEE

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $150.00 1999-06-09
Registration of a document - section 124 $100.00 2000-02-02
Registration of a document - section 124 $100.00 2000-07-07
Registration of a document - section 124 $100.00 2000-07-07
Registration of a document - section 124 $100.00 2000-07-07
Maintenance Fee - Application - New Act 2 2001-06-11 $100.00 2001-05-16
Maintenance Fee - Application - New Act 3 2002-06-10 $100.00 2002-05-08
Maintenance Fee - Application - New Act 4 2003-06-09 $100.00 2003-04-25
Request for Examination $800.00 2004-04-30
Maintenance Fee - Application - New Act 5 2004-06-09 $200.00 2004-05-03
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
QUESTAIR TECHNOLOGIES INC.
Past Owners on Record
CONNOR, DENIS J.
DOMAN, DAVID G.
JEZIOROWSKI, LES
KEEFER, BOWIE
LARISCH, BELINDA
MCLEAN, CHRISTOPHER
QUEST AIR GASES INC.
QUESTOR INDUSTRIES INC.
SHAW, IAN
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 1999-06-09 1 23
Claims 1999-06-09 22 846
Drawings 1999-06-09 25 843
Representative Drawing 2000-11-24 1 15
Description 1999-06-09 33 1,368
Cover Page 2000-11-24 1 45
Drawings 2000-08-28 25 657
Fees 2001-05-16 1 35
Assignment 1999-06-09 3 90
Correspondence 1999-07-26 1 32
Assignment 2000-02-02 6 164
Assignment 2000-07-07 7 253
Correspondence 2000-08-15 1 2
Prosecution-Amendment 2000-08-28 26 685
Assignment 2001-06-15 6 218
Correspondence 2001-06-15 3 99
Assignment 2001-06-15 6 199
Assignment 2001-07-16 2 74
Assignment 2001-07-16 6 213
Correspondence 2001-08-21 1 12
Correspondence 2001-08-24 1 14
Correspondence 2001-08-24 1 17
Correspondence 2001-08-03 1 24
Correspondence 2001-07-30 3 87
Prosecution-Amendment 2004-04-30 1 35