U.S. patent number 3,899,023 [Application Number 05/372,333] was granted by the patent office on 1975-08-12 for equipment for drying gas, in particular air, by refrigeration.
This patent grant is currently assigned to VIA Gesellschaft fur Verfahrenstechnik. Invention is credited to Bernt Borggrafe, Horst Wortmann, Bernd Zander.
United States Patent |
3,899,023 |
Zander , et al. |
August 12, 1975 |
Equipment for drying gas, in particular air, by refrigeration
Abstract
The disclosed equipment provides for the flow of gas to be dried
in a vertically downward direction through a precooling gas/gas
heat exchanger and then in a vertically downward direction through
a removable insert refrigerant cooling coil configuration of a
gas/refrigerant heat exchanger for cooling. A filter removes
impurities in the cooled gas extracted from the lower portion of
the gas/refrigerant heat exchanger before it is recirculated
through a removable insert pipe arrangement of the gas/gas heat
exchanger. Such recirculation enables the cooled gas to precool
newly admitted gas within the gas/gas heat exchanger. It also
increases the temperature of the cooled gas by a prescribed
magnitude before it is exhausted from the gas/gas heat exchanger
for functional use.
Inventors: |
Zander; Bernd (Kettwig,
DT), Borggrafe; Bernt (Hemsbach, DT),
Wortmann; Horst (Frondenberg-Ardey, DT) |
Assignee: |
VIA Gesellschaft fur
Verfahrenstechnik (Dusseldorf, DT)
|
Family
ID: |
5849413 |
Appl.
No.: |
05/372,333 |
Filed: |
June 21, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
165/111;
165/DIG.205; 165/143; 165/178; 62/90; 62/93; 62/272; 165/163 |
Current CPC
Class: |
B01D
53/265 (20130101); F28D 7/085 (20130101); F28D
7/08 (20130101); Y10S 165/205 (20130101) |
Current International
Class: |
B01D
53/26 (20060101); F28D 7/00 (20060101); F28D
7/08 (20060101); F28b 001/00 (); F28f 009/26 () |
Field of
Search: |
;62/90,93,272,317
;165/143,163,178,111 ;55/269 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Davis, Jr.; Albert W.
Assistant Examiner: Richter; Sheldon
Attorney, Agent or Firm: Padden; Frederick W.
Claims
What is claimed is:
1. In an apparatus for drying gas, in particular air, by
refrigeration, including a gas/gas heat exchange and a
gas/refrigerant heat exchanger, said exchangers extending with
their longitudinal axes in a vertical direction, a heat exchanger
insert for at least said gas/refrigerant exchanger, said heat
exchanger insert comprising a plurality of cooling coil elements
being connected in parallel and combined into a closed package and
having a plurality of cooling coil sections being bent in their
longitudinal direction backwards and forwards in an S-like
configuration and extending in a horizontal direction substantially
in parallel, said sections further alternating with regard to the
cross-section of a cooling coil element in a zig-zag manner between
a first and a second plane, adjacent cooling coil elements meshing
with each other so that immediately neighboring sections of
adjacent cooling coil elements provide for a mutual support.
2. An apparatus as defined in claim 1 wherein said immediately
neighboring sections of adjacent ones of said cooling coil elements
are rigidly connected with each other.
3. An apparatus as defined in claim 2 wherein baffles are
accommodated in free hollow spaces between neighboring sections of
said cooling coil elements positioned at the outer sides of said
cooling coil package, said baffles extending substantially over the
entire length of a cooling coil section.
4. An apparatus as defined in claim 3 wherein any of said heat
exchangers is equipped with a heat exchanger insert and wherein
said gas/gas heat exchanger, said gas/refrigerant heat exchanger
and/or said heat exchanger insert each are constructed as modules
replaceable independently of each other.
Description
BACKGROUND OF THE INVENTION
This invention relates to equipment for drying gas, such as air, by
refrigeration and particularly to an equipment arrangement in which
a gas to be dried flows successively through a gas/gas heat
exchanger, a gas/refrigerant exchanger and subsequently again the
gas/gas heat exchanger in a continuous loop.
As is known, the principle of drying gas by refrigeration is based
upon the fact that the dew point of the gas to be dried is lowered
so that humidity contained in the gas is separated, along with at
least a portion of further impurities. Heretofore, in prior art
devices for drying gas by refrigeration the two heat exchanger
columns are positioned in a horizontal direction so that due to the
use of two different kinds of heat exchangers a satisfactory
efficiency is achieved, however, as a result of the horizontal
extension of the columns difficulties are encountered with regard
to an efficient concentrated withdrawal of the separated humidity
or impurities, respectively, as well as with regard to a suitable
guidance of the gas or refrigerant flow because the force of
gravity does not act upon the gas or refrigerant flow in the flow
direction but rather in a direction transverse thereto.
It is known in the prior art to provide a device for separating
humidity from wet gases or vapors wherein the gas flow to be cooled
or refrigerated is guided through two cooling chambers in a
vertical direction. Both chambers are connected in series and
cooled by a common coolant flow. The gas to be cooled is passed
through the first cooling chamber in a downward direction whereas
it passes the second cooling chamber in an upward direction. Thus,
the separated liquid, under the influence of the force of gravity,
travels to the lower end of the cooling chambers from where the
liquid may be readily withdrawn. However, the two prior art cooling
chambers both are designed as gas/refrigerant heat exchangers
whereas a gas/gas heat exchanger is not present so that the overall
efficiency is kept at a relatively low level.
Another known device differs from the above-described prior art
merely insofar as both cooling chambers are not disposed beside
each other but one above the other so that substantially the same
functional operations occur except for the considerably larger
height of construction which in many cases may even be
excessive.
It is an object of the present invention to improve such prior art
devices for achieving both an efficient withdrawal of the
condensate along with a suitable conduct of the gas and refrigerant
flow and simultaneously a good efficiency with respect to the
cooling of the gas to be dried.
SUMMARY OF THE INVENTION
The foregoing and other objects are achieved by an equipment
arrangement which advantageously positions both a gas/gas heat
exchanger and a gas/refrigerant heat exchanger in vertical
direction adjacent each other.
Due to such a structure and configuration of the device according
to this invention the desired goal is reached, namely, that the
height of the construction is low and the condensate accumulates in
a concentrated area with the assistance of the force of gravity
and, moreover, that the entire device exhibits a high cooling
efficiency due to the refeeding of the gas cooled within the
gas/refrigerant heat exchanger into the gas/gas heat exchanger.
In accordance with the illustrative embodiment of this invention, a
gas to be dried is processed vertically downward from an upper
inlet to a lower outlet through a heat exchanger insert of a
gas/gas heat exchanger device. The latter insert includes a
plurality of pipes aligned vertically one above the other and in
the downward path of the gas to be dried. Each of the pipes
illustratively comprises a hollow inner portion extending
longitudinally and in a horizontal plane with the insert. Each of
the pipes supports cooling fins, or ribs, for cooling gas including
the gas from the inlet. Advantageously, the hollow portion of
selected ones of the pipes communicate with another inlet of the
gas/gas heat exchanger for recirculating gas cooled by a
gas/refrigerant heat exchanger through the gas/gas heat exchanger
for precooling newly admitted gas to be dried and for upward
against the force of gravity exhausting the cooled, or dried, gas
to the exterior of the gas/gas heat exchanger for function use.
A gas/refrigerant heat exchanger is used for further cooling of gas
received from the lower outlet of the gas/gas heat exchanger and
then coupling the cooled gas through an impurities and separated
liquid filter to the hollow portion of the pipes in the gas/gas
heat exchanger. The gas/refrigerant heat exchanger also comprises
an insert comprising a cooling coil network arrangement disposed in
a vertically downward path of the gas flow from the gas/gas heat
exchanger via an upper inlet and a lower outlet of the
gas/refrigerant heat exchanger. The latter outlet is coupled to the
filter for communicating the cooled gas thereto for removal of
impurities.
In summary, the present invention provides for the flow of a gas to
be dried in a vertically downward direction through a precooling
gas/gas heat exchanger and thence in a vertically downward
direction through a refrigerant cooling coil configurations of a
gas/refrigerant heat exchanger for cooling. The processing
continues by communicating the cooled gas through a filter for
impurity removal and then by recirculating the purified cooled gas
through a pipe arrangement of the gas/gas heat exchanger. Such
recirculation enables the cooled gas to precool newly admitted gas
within the gas/gas heat exchanger and thereby to increase the
temperature of the cooled gas by a prescribed magnitude before it
is exhausted from the gas/gas heat exchanger for functional
use.
DESCRIPTION OF THE DRAWING
The foregoing objects, features and advantages, as well as others
of this invention, may become more clearly understood by a reading
of the following description of an exemplary embodiment thereof as
shown in the accompanying drawing in which:
FIG. 1 is a side view, partially in section, of a device for drying
gas by refrigeration;
FIG. 2 is a horizontal cross-section through the gas/gas heat
exchanger of FIG. 1, taken along line II--II;
FIG. 3 is a horizontal cross-section through the refrigerant/gas
heat exchanger of FIG. 1 taken along line III--III;
FIG. 4 is a side view, partially in section, of an insert for the
refrigerant/gas heat exchanger according to another embodiment of
the invention; and
FIG. 5 is a vertical section through the insert of FIG. 4 taken
along line V--V.
DETAILED DESCRIPTION
Referring now to FIG. 1, there is illustrated a refrigerating dryer
10 according to one embodiment of this invention having a
vertically extending gas/gas heat exchanger 12 as well as a
gas/refrigerant heat exchanger 14 extending in parallel
thereto.
The gas/gas heat exchanger 12 includes a cylindrical housing 16
enclosing a heat exchanger insert 18 of rectangular cross-section.
Collars 20 are secured to the outer circumference of the insert 18
by means of which the insert 18 rests upon brackets 22 fastened to
the interior surface of housing 16. As apparent in particular from
FIG. 2, pipes 24 supporting cooling ribs 26 extend between two
opposite sides of the insert 18 parallel above and besides each
other.
At the upper end of the gas/gas heat exchanger 12 there is a
stud-like inlet 28 through which the gas to be dried, preferably
air, may enter. This gas is passed through the insert 18 in the
direction indicated by arrow m, thereby flowing through the hollow
spaces defined between pipes 24 and cooling ribs 26, respectively.
From the lower end of the insert 18, the gas to be dried is passed
on to a studlike outlet 30 through which it may escape from the
gas/gas heat exchanger 12 as indicated with the S-shaped dashed
line leading from outlet 30 to a subsequent inlet 40 of the
gas/refrigerant heat exchanger 14.
Cooled gas as derived from the gas/refrigerant heat exchanger
14--the structure of which is explained in greater detail
hereafter--is refed via a stud-like inlet 32 into the gas/gas heat
exchanger 12 whereupon it enters the opposite free openings of
pipes 24. The collar 20 adjacent inlet 32 prevents gas entering
through inlet 32 from being applied to the whole group of pipes 24
simultaneously. Rather, merely those pipes 24 extending below the
collar 20 adjacent inlet 32 are available to receive gas. Through
this lower portion of pipes 24 the gas travels to the right side of
the insert 18, in order to rise there to a maximum height
determined by the collar 20 located at this side of insert 18, and
to enter further pipes (not shown) corresponding to pipes 24 so
that the gas flow is conducted through pipes 24 in an S-like
configuration. The open ends of the upper pipes 24 communicate with
a stud-like outlet 34 through which the dried gas may leave the
refrigerating dryer 10. In the described embodiment according to
FIG. 1, the gas flow is deviated twice, however, principally any
other higher number of deviations may take place.
Gas/refrigerant heat exchanger 14 includes a heat exchanger insert
36 enclosed by a housing 38. Through the stud-like inlet 40 the gas
supplied from gas/gas heat exchanger 12 may enter into the
gas/refrigerant heat exchanger 14 in order to leave same upon
passage of the heat exchanger insert 36 through a stud-like outlet
42 communicating with the inlet 32 of gas/gas heat exchanger
12.
A cooling coil generally designated 44 and having linear tube-like
sections 46 is distributed over the entire height and width of
insert 36 (cf. FIG. 3). Sections 46 traverse insert 36 in a similar
manner as pipes 24 intersect insert 18, except that at their ends
they are connected to subsequent sections 46 through U-connections
48, respectively. To increase the cooling action, the sections 46
may be surrounded by cooling ribs 50 as is conventional in the art.
The beginning of cooling coil 54 communicates with an injection
conduit 52 whereas the end of cooling coil 44 terminates in an
exhaust conduit 54 so that the coolant may be pumped through
cooling coil 44 in a continuous closed loop.
Between outlet 42 and inlet 32 a filter 56 may be interconnected
which then advantageously is located at the coolest point of the
gas flow to be dried and which thus may intercept separated liquid
and impurities in a particularly effective manner.
The bottoms of the two heat exchangers may be provided with outlets
57 and 58, respectively, through which the liquid separated from
the gas flow may be readily withdrawn as under the influence of the
force of gravity it accumulates in the bottom area of the two heat
exchangers and thus concentrates close to the two outlets 57 and
58, respectively.
Accordingly, the refrigerant dryer 10 according to this invention
provides for a suitable withdrawal of the separated impurities and
for a suitable course of the gas flow because it will always
descend from warmer to cooler points and rises from cooler to
warmer points, respectively. It also simultaneously guarantees good
efficiency inasmuch as the cooled gas rising within the gas/gas
heat exchanger 12 pre-cools the gas descending through insert 18 in
direction of arrow m while the gas returning to outlet 34 through
pipes 24 is pre-heated by the descending gas flow thus having
resumed a desired relatively high temperature level when exiting
through outlet 34. In practice, the temperature distribution may be
such that the entering gas is at a temperature of 35.degree. C,
whereas it leaves gas/gas heat exchanger 12 at a temperature of
about 20.degree. C. Upon travel through insert 36 the gas flow may
be at a temperature level of +2.degree. C and that temperature may
have been increased up to +25.degree. C when the gas leaves gas/gas
heat exchanger 12.
FIG. 4 shows a particularly advantageous embodiment of a heat
exchanger insert of this invention having a structure differing
from that of heat exchanger insert 36 of FIG. 1. This insert
likewise exhibits a case 60 receiving cooling coil elements 62, 64
. . . of substantially slice-like configuration and having cooling
coil sections 66, 68 . . . . At their lower ends the individual
slice-like cooling coil elements 62, 64 rest upon supports 70. At
their ends, cooling coil elements 62, 64 terminate into U-bows 72
by means of which they communicate with a manifold 74 connecting
cooling coil elements 62, 64 in parallel.
As evident from FIG. 4, each slice-like cooling coil element 62, 64
comprises a plurality of cooling coil sections 66, 68 bent
backwards and forwards in S-shaped configuration and extending in
parallel with each other in horizontal direction. As indicated by
the dash-dotted zig-zag-lines of FIG. 5 (upper area), cooling coil
sections 66, 68 . . . --with reference to the cross-section of a
slice-like cooling coil element--are bent backwards and forwards in
a zig-zag-like manner from a first plane 78, 82 . . . into a
corresponding second plane 80, 84 . . . and vice versa, so that
each slice-like cooling coil element 62, 64 . . . has a
zig-zag-like configuration with regard to its cross-section.
Cooling coil elements 62, 64 . . . adjacent each other may thus be
interlaced with each other in a comb-like manner, so that a maximum
filling factor for the volume is secured and immediately adjacent
sections 66, 68 . . . of neighboring cooling coil elements 62, 64 .
. . may support each other mutually, thereby providing for a high
mechanical stability of the entire cooling coil system. The mutual
association of the sections of the cooling coil elements or of the
cooling coil elements themselves is clearly illustrated in the
lower portion of FIG. 5.
It will thus be possible to bend the individual cooling coil
elements 62, 64 . . . from one coherent tube so that it will be
unnecessary to use separate additional connecting members at the
points of return as this had been set forth in connection with FIG.
3. As will be understood that this kind of construction will yield
a material cost saving because soldering or brazing operations are
not required any more. Beyond that, reliability will be increased
because leakages due to imperfact soldering work are impossible.
Moreover it is warranted that the individual cooling coil elements
do not exhibit any regions in which the refrigerant would have to
flow in an upward direction. This avoids that impurities contained
in the refrigerant such as oil which might separate in the course
of the passage of the refrigerant through the cooling coil elements
might settle within the cooling coil system. Rather, as the
sections 66, 68 . . . are continuously extending in a downward
direction throughout any danger of a possible accumulation of
impurities within a cooling coil element is removed. While
refrigerants are available for which the occurrence of oil or other
residues do not necessarily have an adverse effect, such
refrigerants exhibit but a comparatively low cooling capacity.
While almost any hollow spaces between adjacent sections bent in a
zig-zag-like manner and belonging to one cooling coil element are
filled by corresponding neighboring sections, free hollow spaces
remain between adjacent sections of the two outer cooling coil
elements through which the gas to be dried might flow without
sufficiently intensive contact with the cooling coil system.
Therefore, into at least a part of these hollow spaces baffles 86
may project which extend substantially over the entire length of
sections 66, 68 and are fastened to the adjacent wall of case 60.
These baffles 86 assure a close contact of the gas current with the
cooling coil elements in the area of the outer hollow spaces,
too.
In order to further enhance the rigidity of the system formed by
cooling coil elements 62, 64, contiguous sections of adjacent
cooling coil elements may be connected with each other for example
by brazing, in particular in the point of return area. Similarly,
the outer cooling coil elements may be affixed to case 60.
The refrigerating dryer according to this invention may be used for
quantities on an order of magnitude of 3,000 m.sup.3. The three
major components of the refrigerating dryer, namely the gas/gas
heat exchanger, the gas/refrigerant heat exchanger and the heat
exchanger insert may be designed as modules which may be composed
due to the prevailing operation conditions with regard to the
amount of gas (air) to be conveyed and the desired temperatures, or
which may be replaced by suitable larger or smaller similar modules
when there is a change in the operation conditions .
* * * * *