U.S. patent application number 13/526614 was filed with the patent office on 2012-12-20 for system and method for cryogenic condensing.
Invention is credited to Alan T. Cheng.
Application Number | 20120318017 13/526614 |
Document ID | / |
Family ID | 46397651 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120318017 |
Kind Code |
A1 |
Cheng; Alan T. |
December 20, 2012 |
SYSTEM AND METHOD FOR CRYOGENIC CONDENSING
Abstract
A method and apparatus for condensing vapor in a gas. A cryogen,
such as liquid nitrogen, may be provided into first and second coil
sets in a condenser housing to cool the condensable vapor in the
housing to condense the vapor into a liquid or solid form. The flow
of cryogen in the first and second coil sets may be independently
controlled, coils in the first and/or second coil sets may have a
substantially equal length, and/or coils in the first and/or second
coil sets may have uppermost portions that are located at a
substantially equal height.
Inventors: |
Cheng; Alan T.; (Naperville,
IL) |
Family ID: |
46397651 |
Appl. No.: |
13/526614 |
Filed: |
June 19, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61498869 |
Jun 20, 2011 |
|
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Current U.S.
Class: |
62/601 ;
62/616 |
Current CPC
Class: |
F25B 39/04 20130101;
B01D 2256/10 20130101; B01D 7/00 20130101; B01D 5/0006 20130101;
B01D 8/00 20130101; F28D 7/0066 20130101; B01D 53/265 20130101;
F28D 7/024 20130101 |
Class at
Publication: |
62/601 ;
62/616 |
International
Class: |
F25J 1/02 20060101
F25J001/02 |
Claims
1. A cryogenic condenser, comprising: a housing defining an
interior space, the housing having a gas inlet for introducing gas
with a condensable vapor and a gas outlet for exhausting gas; first
and second coil sets, each coil set including at least one coil
located in the interior space, each of the coils having an inlet
and an outlet and arranged to conduct a cryogen from the inlet to
the outlet, the coils being arranged to cool the condensable vapor
in the interior space to condense the vapor into a liquid or solid
form; and a cryogen supply including at least one valve and
arranged to independently control flow of cryogen in at least two
of the coils.
2. The condenser of claim 1, wherein the housing defines a
cylindrical space having a top and a bottom, and first coil set is
located above the second coil set.
3. The condenser of claim 1, wherein the housing has a cylindrical
shape having a top and a bottom, and the gas inlet is arranged at a
side of the cylindrical shape and the gas outlet is arranged at the
top of the cylindrical shape.
4. The condenser of claim 3, comprising an inlet baffle arranged at
the gas inlet to direct gas toward the bottom of the cylindrical
shape.
5. The condenser of claim 4, further comprising at least one baffle
at the top or bottom of the cylindrical shape to direct gas flow in
the interior space in a vertical direction.
6. The condenser of claim 4, wherein the inlet baffle is positioned
between the gas inlet and the coils.
7. The condenser of claim 4, further comprising a bottom baffle at
the bottom of the cylindrical shape that inhibits gas flow in a
horizontal direction, and at least one top baffle at the top of the
cylindrical shape that inhibits gas flow in a horizontal
direction.
8. The condenser of claim 1, wherein the coils in the first and
second coil sets have a substantially equal length.
9. The condenser of claim 1, wherein each of the coil sets includes
at least two coils that have a substantially equal length.
10. The condenser of claim 9, wherein the coils in each coil set
have a common inlet conduit and a common outlet conduit.
11. The condenser of claim 9, wherein the coils in each coil set
are nested.
12. A cryogenic condenser, comprising: a housing defining an
interior space, the housing having a gas inlet for introducing gas
with a condensable vapor and a gas outlet for exhausting gas; first
and second coils, each coil being located in the interior space,
having an inlet and an outlet and arranged to conduct a cryogen
from the inlet to the outlet, and having a substantially equal
length from the inlet to the outlet, the coils being arranged to
cool the condensable vapor in the interior space to condense the
vapor into a liquid or solid form; and a cryogen supply arranged to
provide cryogen to the inlet of each of the coils.
13. The condenser of claim 12, wherein the first and second coils
are part of a first coil set that further includes at least a third
coil, the third coil having a length from an inlet to an outlet
that is substantially equal to the length of the first and second
coils.
14. The condenser of claim 12, wherein the first and second coils
are part of a first coil set, the condenser further comprising a
second coil set that includes third and fourth coils that have a
substantially equal length.
15. A method for removing a condensable vapor from a gas stream,
comprising: providing a gas with a condensable vapor into a
condenser housing; providing a liquid cryogen into first and second
coil sets in the condenser housing to cool the condensable vapor in
the interior space to condense the vapor into a liquid or solid
form in the condenser housing; and independently controlling a flow
of liquid cryogen in the first and second coil sets.
16. The method of claim 15, wherein the step of independently
controlling comprises operating at least one valve for a first
cryogen supply for the first coil set independently of operation of
at least one valve for a second cryogen supply for the second coil
set.
17. The method of claim 15, wherein the first and second coil sets
each include: first and second coils, each having an inlet and an
outlet and arranged to conduct a cryogen from the inlet to the
outlet, the first and second coils being nested with the second
coil being at least partially surrounded by the first coil, and the
first and second coils each having an uppermost portion that are
located at a substantially equal height.
18. The method of claim 17, wherein the first and second coil sets
each include at least a third coil that is nested with the first
and second coils, the third coil having an uppermost portion that
is located at a substantially equal height at the uppermost
portions of the first and second coils.
19. The method of claim 15, wherein first coil set is positioned
above second coil set.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional
application Ser. Nos. 61/498,869 filed Jun. 20, 2011, the
disclosure of which are incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and systems for
removing a condensable vapor, such as water vapor, from a gas, and
more particularly, to a cryogenic condenser.
BACKGROUND
[0003] Cryogenic condenser systems for removing condensable vapor
from a gas such as those describes in U.S. Pat. No. 6,505,472 are
generally known in the art. In some applications, particularly
freeze-drying applications that use alcohol base formulations, very
low condensation temperatures are required (i.e. colder than -100 C
and lower than the freezing point of most heat transfer
fluids).
[0004] Freeze drying is a sublimation process that removes water
from a product in the form of ice. Freeze drying is especially
useful in the pharmaceutical industry to remove water from
biological products because it preserves the integrity of the
biological products. In freeze drying, the water-containing or
alcohol containing product is frozen and, under vacuum with the
partial pressure of water vapor reduced below the triple point of
water, the frozen water sublimes and the sublimated ice is removed
from the dryer.
[0005] Accordingly, what is needed is an improved cryogenic
condensing system and method for effectively removing a condensable
vapor, such as water vapor, from a gas stream and which can operate
efficiently and effectively at very low or cryogenic temperatures
often seen during freeze drying cycles. Ideally, the cryogenic
condensing system should be able to handle large thermal cycling in
a freeze drying process without stress cracking caused by thermal
expansion and contraction.
SUMMARY OF INVENTION
[0006] Aspects of the invention relate to systems and methods for
condensing or otherwise removing a condensable vapor from a gas
stream, such as a gas stream used to effect a freeze drying
process. In one embodiment, a gas stream, such as a nitrogen gas
stream containing condensable water vapor, is provided to a
cryogenic condenser that includes two or more coils that carry a
cryogen, such as liquid nitrogen or other similar material. By
passing the gas stream across/near the coils, the coils may remove
heat from the gas stream, causing the condensable vapor in the gas
stream to condense into liquid and/or solid form. Thereafter, the
condensed vapor may be removed from the condenser, and the gas, now
having a reduced amount of condensable vapor, exhausted.
[0007] In one embodiment, the two or more coils of the condenser
may have a substantially equal length from an inlet to an outlet.
This feature may permit the coils to operate in removing
condensable vapor in a more uniform way, e.g., the coils may
operate at the same or similar rate in generating condensate, may
carry similar amounts of cryogen, and/or have other similar
operating characteristics that allow the condenser to operate more
efficiently.
[0008] In another embodiment, the coils may have uppermost portions
that are located at a substantially equal height relative to each
other. This arrangement may allow the coils to experience a same
fluid pressure of cryogen carried in the coils, e.g., due to the
force of gravity, in the coils, and thus the coils may have the
same or similar cryogen flow rates. This may help the coils to
operate in the same, or substantially the same, way with respect to
condensate production.
[0009] In yet another embodiment, the cryogen flow in the coils may
be independently controllable. Such an arrangement may permit the
condenser to continue operation even if one coil fails or otherwise
stops proper operation. For example, if a first coil begins to leak
cryogen, the first coil may be shut down (such as by stopping
cryogen supplied to the coil) while a second coil continues to
operate.
[0010] In one embodiment, a cryogenic condenser includes a housing
defining an interior space with a gas inlet for introducing gas
with a condensable vapor into the interior space and a gas outlet
for exhausting gas. First and second coil sets may be located in
the interior space, with each of the coil sets including at least
one coil having an inlet and an outlet and arranged to conduct a
cryogen from the inlet to the outlet. The coils may therefore be
arranged to cool the condensable vapor in the interior space to
condense the vapor into a liquid or solid form. A cryogen supply
including at least one valve may be arranged to independently
control flow of cryogen in each of the coils and/or coil sets.
Coils of the first and second sets, or coils within at least one of
the sets, may have a substantially equal length from the inlet to
the outlet, and/or may have uppermost portions that are located at
a substantially equal height relative to each other.
[0011] In one embodiment, the condenser housing may define a
cylindrical space having a top and a bottom, and a first of the
coil sets may be located above a second of the coil sets in the
interior space. Alternately, the coils may be nested or be arranged
side-by-side. The housing may have the gas inlet arranged at a side
of the cylindrical space and the gas outlet arranged at the top of
the cylindrical space. An inlet baffle may be arranged at the gas
inlet to direct gas toward the bottom of the cylindrical shape,
and/or other baffles may be provided, e.g., at the top or bottom of
the cylindrical space, to direct gas flow in the interior space in
a vertical direction.
[0012] In one embodiment, each of the coil sets includes at least
four coils that have a substantially equal length and that are
arranged in a nested form. The coils of each set may be provided
with cryogen from a common conduit. Cryogen exhausted from the
outlets of the coils may be removed from the condenser via a common
cryogen outlet.
[0013] In another aspect of the invention, a method for removing
condensate from a gas stream includes providing a gas with a
condensable vapor into a condenser housing, providing a liquid
cryogen into first and second coil sets in the condenser housing to
cool the condensable vapor in the interior space to condense the
vapor into a liquid or solid form in the condenser housing, and
independently controlling a flow of liquid cryogen in the first and
second coil sets. Independent control of flow of cryogen for the
coil sets may be performed by operating at least one valve for a
first cryogen supply for the first coil set independently of
operation at least one valve for a second cryogen supply for the
second coil set. The first and second coil sets may each include
first and second coils, each having an inlet and an outlet and
arranged to conduct a cryogen from the inlet to the outlet. The
first and second coils may be nested with the second coil being at
least partially surrounded by the first coil, and the first and
second coils each having a substantially equal length and/or an
uppermost portion that are located at a substantially equal height.
Each of the first and second coil sets may include at least a third
coil that is nested with the first and second coils, with the third
coil having a substantially equal length as the first and second
coils and/or an uppermost portion that is located at a
substantially equal height at the uppermost portions of the first
and second coils. Liquid cryogen may be provided to the first,
second and third coils of each coil set with liquid cryogen from a
common conduit, and the first coil set may be positioned above the
second coil set.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and other aspects, features, and advantages of the
present invention will be more apparent from the following, more
detailed description thereof, presented in conjunction with the
following drawings, wherein:
[0015] FIG. 1 is a perspective view of a cryogenic condenser in an
illustrative embodiment;
[0016] FIG. 2 shows an upper right side perspective view of an
embodiment of a cryogenic condenser that is similar to that shown
in FIG. 1;
[0017] FIG. 3 is a lower left side perspective view of the FIG. 2
embodiment;
[0018] FIG. 4 is a front view of the FIG. 2 embodiment;
[0019] FIG. 5 is a right side view of the FIG. 2 embodiment;
[0020] FIG. 6 shows a cross sectional view along the line 6-6 as
shown in FIG. 5;
[0021] FIG. 7 shows a cross sectional view along the line 7-7 as
shown in FIG. 4;
[0022] FIG. 8 shows a side view of the first coil set of the FIG. 2
embodiment;
[0023] FIG. 9 shows a top view of the first coil set of the FIG. 2
embodiment;
[0024] FIG. 10 shows a cross sectional view along the line 10-10 in
FIG. 9; and
[0025] FIG. 11 shows a perspective view of the coil set of FIGS.
8-10.
DETAILED DESCRIPTION
[0026] It should be understood that illustrative embodiments are
described in accordance with aspects of the invention. However, the
embodiments described are not necessarily intended to show or
incorporate all aspects of the invention, but rather are used to
describe a few illustrative embodiments. Thus, aspects discussed
herein are not intended to be construed narrowly in view of the
illustrative embodiments. In addition, it should be understood that
aspects of the invention described may be used alone or in any
suitable combination with other aspects also described.
[0027] FIG. 1 shows an illustrative embodiment of a cryogenic
condenser 1 that incorporates one or more aspects of the invention.
In this embodiment, the condenser 1 includes a housing 10 that
defines an interior space that has a cylindrical shape. However, it
should be understood that the housing 10 may have any suitable
shape, size or other arrangement, and may define an interior space
having any suitable size or shape, such as a box shape, a spherical
shape, etc. The housing 10 includes a gas inlet 11 through which a
gas having a condensable vapor (such as air or nitrogen gas
including water vapor) may be introduced into the housing 10. In
this embodiment, the gas inlet 11 is arranged at a side of the
housing 10, but may be located at any suitable location or
locations, such as the top, bottom, and/or side(s) of the housing
10. The housing 10 also includes a gas outlet 12 through which gas
may exit the housing 10, e.g., after having at least some
condensable vapor removed. In this embodiment, the gas outlet 12 is
arranged at the top of the housing 10, but may be arranged at the
bottom, side(s) and/or the top, as desired. (Although portions of
housing 10 are referred to as being a top, bottom, or side, these
references are for convenience and do not necessarily require that
the condenser 1 be used in any particular orientation. For example,
condenser 1 may be used so that gas outlet 12 at the "top" is
arranged at a position that is below, or at a same height, as gas
inlet 11, e.g., with housing 10 tilted so that both the gas flow at
inlet 11 and outlet 12 are generally in a horizontal plane.)
[0028] The condenser 1 includes first and second coil sets 13a, 13b
(which may each include one or more coils) in the interior space of
the housing that are arranged to cool the condensable vapor so as
to condense the vapor into a liquid or solid form, e.g., for
removal from the gas provided at the gas inlet 11. For example, in
some applications, it may be desired to remove water vapor from a
gas stream (e.g., including mostly air or nitrogen gas). The coils
sets 13a, 13b may be arranged to cool the water vapor so as to
cause the water vapor to condense into liquid or solid water (e.g.,
water droplets or ice). Once condensed into liquid and/or solid
form, the water may be removed, e.g., via a condensate outlet 14
(e.g., a pipe or opening in the housing 10) located at a bottom of
housing 10. If the condensable vapor is condensed into solid form,
the ice or other solid may be removed from housing 10 in any
suitable way, such as by scraping coils sets 13 to remove the
solid, which is then removed by a conveyor belt, falling through a
condensate outlet 14 opening in housing 10. Alternately, coil sets
13 may be heated (or the solid ice otherwise heated) to change the
condensate to a liquid form or otherwise cause the solid to be
removed from coil sets 13, which may then fall from coils sets 13
for removal.
[0029] In accordance with one aspect of the invention, one or more
coils in the coil sets may have a length from an inlet to an outlet
that is the same or substantially the same. That is, a length of a
coil in the first coil set 13a may be equal or substantially equal
to a length of a coil in the second coil set 13b, and/or a length
of a coil in the first coil set 13a may be equal or substantially
equal to a length of another coil in the first coil set 13a. In
this context, the length of a coil from the inlet to the outlet is
the length of a region of the coil between the inlet and the outlet
where the coil functions to remove heat from gas in the housing 10
to help cause condensation of the condensable vapor. By having the
length of the coils be the same or substantially the same, the
coils may remove heat from the interior space at a same or similar
rate, may produce condensate at a same or similar rate, may carry a
same or similar amount of cryogen or other cooling substance,
and/or have other similar operating characteristics. Having the
coils (or at least some coils) in the housing 10 operate with the
same or similar condensate forming characteristics, the condenser 1
may operate more efficiently and/or effectively. For example, equal
length coils may carry a same volume and/or flow rate of cryogen,
and thus share the same or similar cooling rate, condensate
generation or other characteristics, helping to avoid one coil
being colder or warmer (on average) than another. Avoiding such an
imbalance may help avoid excessive ice production on one coil
versus another, and/or undesirably low condensate production by one
coil versus another.
[0030] Accordingly, in one aspect of the invention, one coil set,
such as the first coil set 13a, may include two or more coils that
have a same or substantially the same length from inlet to outlet
as each other. In another embodiment, one or more coils in one coil
set (such as the first coil set 13a) may have the same or
substantially the same length as one or more coils in the other
coil set (such as the second coil set 13b). The coils may be
stacked one on the other, e.g., as shown for the coil sets 13a, 13b
in FIG. 1, may be nested one inside the other (as discussed in more
detail below where one outer coil at least partially surrounds
another inner coil), or have another suitable arrangement, such as
side-by-side positioning.
[0031] In another aspect of the invention, the cryogen supply for
the coil sets in a condenser may be individually controlled. Such
an arrangement may permit the condenser to continue operation,
albeit at a potentially lower output (e.g., a lower condensate
output), if one of the coil sets fails or otherwise stops proper
operation. For example, if the first coil set 13a in the FIG. 1
arrangement begins to leak cryogen, the first coil set 13a may be
shut down (such as by stopping cryogen supplied to the coil set
13a) while the second coil set 13b continues to operate. Continued
operation of a condenser may be important in some operations, such
as where the condenser is involved in removing vapor as part of a
batch treatment process that cannot be stopped without causing
damage to the product being treated (such as a food product) or
otherwise incurring loss. Thus, the condenser may be enabled to
continue operation to complete a batch and repaired after
processing of the batch of product is complete. As shown in FIG. 1,
the first and second coil sets 13a, 13b each have respective
cryogen supply conduits 14a, 14b that are part of a cryogen supply.
The cryogen supply may also include valves 20a, 20b for each of the
conduits 14a, 14b or other suitable arrangements for controlling
the flow of cryogen to the coil sets 13a, 13b. Of course, flow of
cryogen to a coil set 13 may be controlled in other ways, such as
by controlling operation of a pump, insertion of a plug or other
stop in the conduit 14, and/or in other ways. As discussed above,
this aspect of the invention may be used with respect to coils in a
set that are stacked as shown in FIG. 1, nested, arranged in a
side-by-side fashion, and/or in other ways.
[0032] Another aspect of the invention shown in FIG. 1 is that the
condenser housing 10 includes the gas inlet 11 at a side of the
housing arranged so that gas enters the housing 10 in a generally
horizontal direction, and the gas outlet 12 is arranged at a top of
the housing 10 so that gas exits the housing 10 in a generally
vertical direction. Thus, in one aspect of the invention, gas may
enter the housing 10 of the condenser 1 in a direction that is
generally transverse, e.g., perpendicular, to a direction in which
gas exits the housing 10. In addition, the condenser 1 may include
an inlet baffle 15 arranged at the gas inlet 11 to direct gas
toward the bottom of the housing 10, as well as potentially toward
a side of the housing 10 opposite the gas inlet 11. In this
embodiment, the inlet baffle 15 is arranged as a curved sheet, but
may take any suitable form, including one or more flat plates,
fins, conduits, etc. The condenser 1 may also include one or more
baffles 16 near a bottom of the housing 10, e.g., to generally
direct gas flow upwards and toward the coil sets 13. In this
embodiment, one baffle 16 is located between a bottom of the
housing 10 and the second coil set 13b toward a side of the housing
that is offset from the gas inlet 11. Of course, two or more
baffles or other elements could be used to influence gas flow, and
could be arranged in any suitable way. This embodiment also
includes two baffles 17 near a top of the housing 10. These baffles
17 may function to generally direct gas flow toward the gas outlet
12, and/or to inhibit flow of gas from the gas inlet 11 from "short
circuiting" to the gas outlet 12. For example, a forward baffle 17a
may be arranged to help prevent gas entering at the gas inlet 11
from traveling upwardly, along the inlet baffle 15 and directly to
the gas outlet 12. Again, the baffles 17 may be arranged in other
suitable ways, and using other suitably configured elements.
[0033] FIG. 2 and FIG. 3 show a upper right side perspective view
and a lower left side perspective view of an embodiment that is
similar to that shown in FIG. 1. Like the FIG. 1 embodiment, the
condenser 1 shown includes a housing 10 (shown in dashed line to
reveal the internal components of the condenser 1) with a generally
cylindrical shape, a gas inlet 11 at a side of the housing 11, and
a gas outlet 12 at a top of the housing. A pair of coils sets 13a
and 13b are also included, although in this embodiment each coil
set 13 includes four coils that are nested. In accordance with an
aspect of the invention, and as described in more detail below, the
coils in each coil set 13 have a same or substantially same length,
and have an uppermost portion that are at the same or substantially
the same height, e.g., to help ensure similar cryogen flow rates in
the coils. In addition, the coil sets 13 are individually
controllable, i.e., a supply or flow of cryogen in the coils of
each set may be controlled independent of each other, e.g., by
controlling flow in the supply conduits 14a, 14b for the coil sets
13a, 13b. Although the coil sets 13 share a common cryogen outlet
18, the coil sets 13 may be provided with individual cryogen
outlets 18, if desired.
[0034] FIGS. 4 and 5 show a front view and a right side view (i.e.,
a view from a side opposite of the gas inlet 11) of the condenser
1. As can be seen in FIGS. 4 and 5, the coils in each of the coil
sets 13a, 13b have a different pitch, i.e., a different spacing
between adjacent coil loops. That is, because the coils in each set
13 have a same length, the coils in the outer regions of the coil
set 13 will have a greater pitch (larger distance between adjacent
coils) than coils in the inner regions of the coil set 13. Support
structure 22 may be used to help support the weight of the coils,
as well as maintain a desired radial and/or axial location of the
coils relative to each other. The support structure 22 may also
allow the coils to expand (lengthen) and contract (shorten) in
response to temperature changes or other causes. In this embodiment
the support structure 22 includes vertically oriented bars that are
connected together by horizontal stays at upper and lower ends of
the housing 10, but other arrangements are possible.
[0035] To help illustrate the coil arrangement in the coil sets 13,
FIGS. 6 and 7 show cross sectional views along the lines 6-6 and
7-7 as shown in FIGS. 5 and 4, respectively. For example,
considering the first coil set 13a on the right side of FIG. 6, the
outermost coil 5 includes six total loops, whereas the adjacent
coil 4 has seven total loops. Stepping inwardly, the next coil 3
has eight total loops, and the innermost coil 2 has eleven total
loops. As will be described in more detail below, the innermost
coil 2 has two sets of coil loops--one inner set and one outer set.
Because the innermost coil 2 has a relatively small diameter as
compared to the more outer coils, the innermost coil 2 is provided
with inner and outer coil loops to provide coil 2 with the same
length as the other coils in the coil set 13a. Of course, the same
coil length could be provided in other ways, such as by further
reducing the pitch of coil loops in the coil 2.
[0036] As can also be generally seen in FIG. 6, the cryogen supply
conduits 14a, 14b provide cryogen to a respective supply manifold
near a bottom of the respective coil set 13a, 13b. The inlet of
each coil in the set (e.g., coils 2, 3, 4 and 5 of the coil set
13a) is connected to the supply manifold. From the manifold, each
coil 2, 3, 4, 5 extends upwardly to an uppermost portion (indicated
generally at reference 19 in FIG. 6). From the uppermost portion,
cryogen in the coils flows in a generally downward direction to an
exhaust manifold near a bottom of the set 13 to which the outlet of
the coils is connected. The exhaust manifold is connected to the
cryogen outlet 18 so that cryogen may exit the condenser 1 after
flowing through the coils.
[0037] FIG. 8 shows a side view and FIG. 9 shows a top view of the
first coil set 13a from the FIGS. 2-7 embodiment. Although the coil
sets 13 may be arranged differently from each other, in this
embodiment, the coil sets 13a, 13b have substantially the same or
identical arrangement. By arranging the coil sets 13a, 13b in the
same way, the coils may perform in approximately the same way,
e.g., have the same or similar condensate forming characteristics.
As can be seen in FIG. 8, the cryogen supply conduit 14a is
connected to the supply manifold 23 near a bottom of the coil set
13a. The inlets of the coils 2, 3, 4, 5 are connected to the supply
manifold 23 and extend upwardly to an uppermost portion (indicated
generally at reference number 19) from which each of the coils
begin to have a coil loop shape that spirals generally downwardly
toward the bottom of the coil set 13a. Thus, in one aspect of the
invention, two or more coils in a coil set may have uppermost
portions that are located at a same height. By having these
uppermost portions located at approximately a same height, the
coils may experience a same fluid pressure, e.g., due to the force
of gravity, in the coils, and thus tend to have similar cryogen
flow rates. This may help the coils to operate in the same, or
substantially the same, way with respect to condensate production,
particularly if gravity is relied on at least in part to cause the
flow of cryogen in the coils. The three outer coils 3, 4 and 5 all
spiral downwardly from the uppermost portion (e.g., 19) and connect
to the exhaust manifold 24 at the bottom of the coil set 13a. The
innermost coil 2, however, is somewhat different. As mentioned
above, the innermost coil 2 has inner and outer coil loops.
Although the innermost coil 2 spirals downwardly at the inner coil
loop 2b (see FIG. 9) from the uppermost portion (e.g., at 19) to
near the bottom of the coil set 13a, the coil 2 makes a turn (at
reference 2c in FIG. 9) and begins to spiral upwardly at the outer
coil loop 2a. Near the top of the coil set 13a, the outer coil loop
2a terminates and the outlet of the coil 2 extends downwardly for
connection to the exhaust manifold 24. Though not shown in FIGS. 8
and 9, the exhaust manifold 24 may be connected to the cryogen
outlet 18 for removal of cryogen from the condenser 1. FIG. 10
shows a cross sectional view along the line 10-10 in FIG. 9 and
provides a close-up view of the inlets of the coils 2, 3, 4, 5
extending from the supply manifold 23 upwardly to the top of the
coil set 13a. For further reference, FIG. 11 shows a perspective
view of the coil set 13a with the inner coils shaded more lightly
and outer coils shaded more darkly.
[0038] The coils of the coil sets, the cryogen supply conduits,
supply and exhaust manifolds and cryogen outlet may be made of any
suitable material, such as a stainless steel tubing or other
suitable material, e.g., that can withstand temperature gradients
to be experienced using a liquid cryogen in the coils and a
potentially significantly warmer gas environment around the coils.
Similarly, other components of the condenser 1 may be made of
stainless steel or other suitable material, e.g., to withstand the
expected temperature variations, potentially corrosive environments
(such as for use with a volatile vapor condensate that is highly
corrosive to metals or other materials), and other operating
conditions. Although the coils in the embodiments described above
have a helical shape with generally circularly shaped loops, other
arrangements are possible. For example, the coils could have a
helical configuration with loops having a square, rectangular,
elliptical, triangular or other suitable shape, the coils could
have a flat, spiral shape (e.g., where each coil is generally
located in a single plane), a serpentine shape, or other suitable
configurations. The cryogen may be a liquid material, such as a
liquid nitrogen, liquid carbon dioxide, liquid argon, liquid
oxygen, liquid helium, liquid air or other suitable material, or
may be a higher temperature liquid, gas or mixture of liquid and
gas. Flow of cryogen in the coils may be controlled in any suitable
way, and using any suitable control parameters. For example, the
condenser 1 may include one or more sensors to detect temperature,
gas flow rates, condensate production rates, condensable vapor
concentration in the inlet gas, cryogen flow rates, cryogen supply
and/or outlet temperatures, and/or other parameters at one or more
locations. A controller (e.g., including a suitably programmed
general purpose computer with suitable software or other operating
instructions or other suitable electronic circuitry, one or more
memories (including non-transient storage media that may store
software and/or other operating instructions), valves, pumps,
temperature sensors, pressure sensors, input/output interfaces
(such as a visible display, keyboard, mouse or other pointing
device, printer, speaker, etc.), communication buses or other
links, switches, relays, triacs, or other components necessary to
perform desired input/output or other functions) may use the
condenser parameter information (which may include user input
information) to control one or more aspects of the condenser
operation, such as gas inlet flow rate, cryogen flow rate to one or
more coils, condensate removal (e.g., operate a scraper to remove
ice from one or more coils based on detected conditions), and so
on.
[0039] Having thus described several aspects of at least one
embodiment of this invention, it is to be appreciated various
alterations, modifications, and improvements will readily occur to
those skilled in the art. Such alterations, modifications, and
improvements are intended to be part of this disclosure, and are
intended to be within the spirit and scope of the invention.
Accordingly, the foregoing description and drawings are by way of
example only. It will be apparent that other embodiments and
various modifications may be made to the present invention without
departing from the scope thereof. The foregoing description of the
invention is intended merely to be illustrative and not restrictive
thereof. The scope of the present invention is defined by the
appended claims and equivalents thereto.
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