US3750415A

US3750415A - Method and apparatus for drying a gas and chilling it to low temperatures

Info

Publication number: US3750415A
Application number: US00230752A
Authority: US
Inventors: W Peuchen; G Pase
Original assignee: PEUCHEN Inc
Current assignee: WILSTAN Corp; GC Industries Inc
Priority date: 1972-03-01
Filing date: 1972-03-01
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07
Also published as: JPS48100738A; FR2174137B1; JPS5333777B2; IT977526B; DE2310068A1; CA987118A; FR2174137A1; GB1418345A

Abstract

A method and apparatus are provided for continuously drying and chilling a high temperature, pressurized gas such as air to subzero temperatures. The high temperature pressurized gas is passed alternately through each of two parallel heat exchangers containing cooling coils through which cold refrigerant from a refrigeration system is passed. While one of the heat exchangers is being cooled by the cold refrigerant, the hot, pressurized gas is passed through it in heat exchange relationship with the cooling coils. Simultaneously, the other heat exchanger is cleared of moisture and other condensables by passing hot refrigerant gas from the compressor of the refrigeration system through its cooling coils. Before reversing the function of the heat exchangers, the flow of hot refrigerant gas to the one being defrosted is terminated and replaced with the flow of cold refrigerant to cool it in order to prevent carryover of moisture on changing stages of operation. A continuous flow of cooled, dried pressurized gas is obtained from the two heat exchangers and can be passed through a third heat exchanger provided with refrigerated coils to further chill the gas to sub-zero temperature. Prior to being passed to the third heat exchanger, the cooled gas from the two parallel heat exchangers can be cycled through a preliminary heat exchanger to effect pre-cooling of the entering hot, pressurized gas.

Description

United States Patent 1 Peuchen et al.

[451 Aug. 7, 1973 METHOD AND APPARATUS rort DRYING A GAS AND CHILLING 11' To Low TEMPERATURES [75] Inventors: Wilfred S. Peuchel, Wilmington;

Glenwood K. Pase, Whitehall, both of Del.

[73] Assignee: l'eucllel Inc Wilmington, Del.

[22] Filed: Mar. 1, 1972 [21] Appl. No.: 230,752

[52] 11.8. C1. ..,62/93,' 425/387, 62/150, 62/120, 62/272, 62/278, 62/81, 62/324 [51] Int. Cl. F25b 43/00 [58] Field of Search 62/93, 150,272, 62/95, 120, 278, 81; 425/387 8 [56] References Cited UNITED STATES PATENTS 2,867,988 1/1959 2,903,861 9/1959 2,960,840 11/ 1960 3,499,295 3/ 1970 3,500,497 3/1970 3,572,052 3/1971 Toth 62/278 FOREIGN PATENTS OR APPLICATIONS 642,948 6/1962 Canada 62/93 Primary Examiner-William .l. Wye

57 ABSTRACT A method and apparatus are provided for continuously drying and chilling a high temperature, pressurized gas such as air to sub-zero temperatures. The high temperature pressurized gas is passed alternately through each of two parallel heat exchangers containing cooling coils through which cold refrigerant from a refrigeration system is passed. While one of the heat exchangers is being cooled by the cold refrigerant, the hot, pressurized gas is passed through it in heat exchange relationship with the cooling coils. Simultaneously, the other heat exchanger is cleared of moisture and other condensables by passing hot refrigerant gas from the compressor of the refrigeration system through its cooling coils. Before reversing the function of the heat exchangers, the flow of hot refrigerant gas to the one being defrosted is terminated and replaced with the flow of cold refrigerant to cool it in order to prevent carryover of moisture on changing stages of operation. A continuous flow of cooled, dried pressurized gas is obtained from the two heat exchangers and can be passed through a third heat exchanger provided with refrigerated coils to further chill the gas to sub-zero temperature. Prior to being passed to the third heat exchanger, the cooled gas from thetwo parallel heat exchangers can be cycled through a preliminary heat exchanger to effect pre-cooling of the entering hot, pressurized gas.

9 Claims, 4 Drawing Figures 11 3,750,415 [4 1 Aug. 7; 1973 United States Patent [1 1 Peuchen et al.

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2 ,3 Al l 2 gi WWW- H 4. l v [0 H H H 9 a [I a w 2 11 m. v qlv PATENTEU AUG H975 SHEET 1 OF 2 METHOD AND APPARATUS FOR DRYING A GAS AND CHILLING IT TO LOW TEMPERATURES This invention relates to an improved method and apparatus for chilling and removing moisture from a hot, pressurized gas such as air by directing the gas through heat exchangers containing cold refrigeration coils, whereby condensed moisture is periodically removed from the heat exchangers without interrupting the continuous function of the system and without requiring the utilization of additional energy supplied from sources external to the apparatus.

More specifically, the present invention is directed to an improved method for providing a continuous flow of chilled, dried, pressurized gas by passing a stream of hot, pressurized gas through one of a pair of heat exchangers containing cooling coils which are chilled by refrigerant from a refrigeration system containing compressor and condenser means. Simultaneously with the passage of refrigerant through the first of the pair of heat exchangers to effect cooling and removal of condensables, the second of the pair of heat exchangers is cleared of condensed moisture by directing through its cooling coils aflow of hot refrigerant gas directly from the compressor of the refrigeration system. Periodically the cycle is reversed so that the first heat exchanger is defrosted in this manner, while the coils of the second heat exchanger are chilled and used to cool and remove condensables from the hot, pressurized gas now passing through it. ln this way both a continuous flow of gas and continuous operation of the refrigeration compressor are maintained. To prevent any carryover of moisture or other condensables on changing cycles, transition stages are employed whereby, prior to switching the flow of pressurized gas from one heat exchanger to the other, the flow of hot refrigerant gas from the compressor into the heat exchanger being defrosted is terminated, and a flow of cold refrigerant from the refrigeration system is directed into its coils while, at the same time, pressurized gas continues to be passed over the chilled coils of the other heat exchanger.

Particularly in the blow-molding of plastics and similar procedures it is important to have a continuous flow of compressed, dry gas such as air available at a temperature of around 60 F. to use in chilling the inner surfaces of the blow-molded products. ,By chilling these plastic inner surfaces below the flow-point of the plastic, the removal of the article from the forming mold is facilitated, thereby increasing the productivity of the mold by shortening the length of time the product is in the molding and setting stage. Further, by using a chilled, pressurized gas such as air it is possible to carry out the blow-molding and chilling steps in a single step using the same gas for both functions.

Various procedures and apparatus have been suggested for producing a flow of chilled, dry, pressurized gas suitable, for example, for use in the abovedescribed manner in plastics blow-molding operations. Frequently, these systems enploy refrigerated heat exchangers to cool and remove moisture from the gas.

Accordingly, all these types of systems are faced with the problem of removing the condensed moisture at intervals from the heat exchanger units.

In some devices, such as that described in U.S. Pat.-

No. 2,867,988 to Brandt, external electric power is supplied from time to time to heating units to defrost the heat exchanger coils. This, of course, involves an additional expenditure of power as well as the expense of providing and maintaining the electrical heating system itself. Other systems have required that the chilling and drying operation be periodically terminated to permit defrosting of the heat exchanger coils. Still other systems require the frequent cycling of the refrigeration compressors, thus shorteningtheir life expectancy and increasing maintenance costs. As will be appreciated, each of these procedures has the disadvantage that they increase production costs by causing delays and requiring added maintenance and expense.

It is accordingly a general object of the present invention to provide an improved method and apparatus for producing chilled, dry, pressurized gas.

It is another object of the present invention to provide an improved air dryer and chiller which operates continuously and permits removal of condensables from the apparatus without the need for externally supplied heat energy or for interrupting the continuous chilling and drying of gas passing through the system.

It is yet a further object of the present invention to provide a method and apparatus for continuously chilling and drying pressurized gas by passing it through chilled heat exchanger means which employ hot refrigerant gas from the same refrigeration compressors used to provide cold refrigerant to the heat exchangers to effect removal of condensables from the heat exchangers.

I It is still another object of the present invention to provide a method and apparatus for chilling and drying of pressurized gas whereby acontinuous flow of the pressurized gas is maintained by employingparallel heat exchangers for chilling and removing water vapor and other condensables from the gas, which heat exchangers are alternately cooled by cold refrigerant and cleared of condensates by hot refrigerant gas, both of which are provided by the refrigeration compressor unit, which is operated continuously.

Another object of this invention is to provide a method and apparatus for chilling and drying pressurized gas whereby a continuous cyclic system is employed which permits chilling and drying of the compressed gas and removal of condensables without any carryover of condensables into the chilled, dry, pressurized gas.

The method and apparatus of the present invention whereby the aforementioned and other objects are achieved will best be understood and appreciated by reference to the accompanying drawings and the following description thereof, which describes a specific embodiment of this invention.

FIGS. 1, 2 and 3 are block schematic diagrams which depict the cyclic operationof the present invention.

FIG. 4 is a semi-schematic drawing with interior views showing the complete heat exchanger and refrigeration system of the present invention for cooling and drying pressurized air.

Reference is first made to FIGS. 1, 2, and 3 for an understanding of the four-stage operation of the invention. High temperature, pressurized gas is supplied to the system by the externally located compressor 51. In the first stage, depicted in FIG. 1, high temperature, pressurized gas is passed through the heat exchanger A where moisture and other condensables are condensed out of the gas by means of refrigeration coils (not shown) cooled by refrigerant supplied by the compresset 52, and the condenser 54. Hot, compressed refrigerant gas from the compressor 52, which is not directed to the condenser 54 is simultaneously passed into the refrigeration coils (not shown) of the heat exchanger B to melt ice and other condensables deposited when the heat exchanger is in the stage of operation in which it cools the high temperature, pressurized gas. Both hot and cold refrigerant are returned from the refrigeration coils of the heat exchangers, A and B, to the compressor 52 by conduits which are not shown. Following cooling and removal of condensables in the heat exchanger A, during the first stage of operation, the pressurizedgas leaves the heat exchanger and is introduced into the heat exchanger C, which contains refrigeration coils (not shown) maintained at very low temperature (i.e., below F.) by means of refrigerant from the compressor 53 and condenser 55. The dry, pressurized gas, which is cooled to a temperature of 60 F. emerges from the heat exchanger C in a continuous flow. Refrigerant from the refrigeration coils in the heat exchanger C is returned to the compressor 53 by means of a suitable conduit, not shown. During this first-stage operation, the heat exchanger B, which is being defrosted by hot refrigerant gas from the compressor 52, is by-passed by the flow of pressurized gas through the system.

In the second stage of operation, shown in FIG. 2, the passage of pressurized gas through the heat exchangers, A and C, continues as in the first stage operation. The flow of hot refrigerant gas from the compressor 52 into the refrigeration coils of the heat exchanger B is discontinued however, and instead, cold refrigerant from the condenser 54 is passed into the coils of B to prevent any subsequent carryover of moisture when the pressurized'gas flow is changed from the heat exchanger A in the third stage.

During the third stage of operation, the functions of the heat exchangers, A and B, are exactly reversed from those of the first stage. As shown in FIG. 3, hot, pressurized gas from the compressor 51 is introduced into the heat exchanger B where it is cooled and condensables removed by refrigeration coils cooled by refrigerant supplied from the condenser 54. Simultaneously, the heat exchanger A is excluded from the flow of pressurized gas and is cleared of frozen condensables by means of hot refrigerant gas from the compressor 54. The stream of chilled, pressurized gas emerges from the heat exchanger B and through the heat exchanger C, maintained at sub-zero temperature, from where it continues to emerge in a continuous flow at a temperature of -60 F.

The fourth, and final, stage of operation is not shown in FIGS. 1, 2, and 3, but consists of a transitional precooling as in stage 2, before returning to stage 1. In stage 4, the flow of pressurized gas is continued through the heat exchangers, B and C, as in stage 3. Defrosting of the heat exchanger A is discontinued, however, by terminating the flow of hot refrigerant gas from the compressor 52. Instead, the heat exchanger A is pre-cooled by directing the flow of refrigerant from the condenser 54 into the refrigerant coils of A. In this stage, the cooling of the pressurized gas in the heat exchanger B is continued by also directing the flow of refrigerant from the condenser 54 into its refrigeration coils.

Referring now in detail to FIG. 4 for a more specific description of an embodiment of the present invention,

dual cylindrical, parallel heat exchangers are shown at l and 1A with coils for carrying cold refrigerant shown within the cylindrical heat exchanger columns at 36 and 37, respectively. An additional heat exchanger, consisting of 6 parallel, horizontal, interconnected cylinders, is shown at 3. Within each cylinder are coiled tubes, 38, which are interconnected and which carry cold refrigerant supplied from the condenser 7. Compressor 4 provides hot, pressurized gas through the pipe 25 into the condenser 6. Suitable liquid coolant is supplied to the coils 41 within the condenser 6 and through the orifice 44 and removed through 43. This liquid coolant is cycled from a source not shown. Cold refrigerant liquid is passed from the condenser 6 through pipe 27 to the

solenoid valves

10 and 12 which control the flow of cold refrigerant liquid, respectively, through the

thermostatic expansion valves

16 and 17. Alternately, pipe 26 provides for the direct passage of hot, pressurized refrigerant gas from the compressor 4 to the solenoid valves 11 and 13. Cold refrigerant, after passing through the refrigeration coils 36 and 37, is removed as gas from the top of the heat exchangers l and 1A, respectively, by means of pipe 28 which returns the refrigerant to the compressor 4. Compressor 5 provides hot, compressed refrigerant gas through the pipe 29 to the condenser 7 where it is condensed into cold refrigerant liquid by a suitable coolant passing through the orifice 46 to the cooling pipes 42 and back out through 45 where it is recycled and chilled by suitable circulating and cooling mechanisms not shown. Cold refrigerant liquid passes from the condenser 7 through the pipe 31 to the solenoid control valve 14 and the thermostatic expansion valve 18, enters the heat exchanger 3 and is carried through the heat exchanger coils 38. The cold refrigerant is finally returned by means of the pipe 32 as gas to the compressor 5. Pipe 30 provides for direct passage of hot, compressed refrigerant gas to the solenoid valve 15 and then into the heat exchanger pipe 38 for cycling through the heat exchanger coils 38 and return by pipe 32 to the compressor 5.

Valve means are provided at 19 for admitting into the system hot, pressurized air which is to be chilled and dried. An optional pre-cooling cylinder isshown at 2 and provided with cooling coils 40. A pipe passes from the top of the pre-cooler 2 and divides into the separate pipes, 20 and 21, which enter the bottom of the heat exchangers l and 1A. Additional pipes exit, respectively, at the top of each of the heat exchangers l and 1A and are each provided with the solenoid valves 8 and 9, respectively. The pipes emerging from the top sides of the heat exchangers A and IA merge into pipe 22 which returns to the bottom of the pre-eooler where it is connected into the cooling coil 40. Pipe 23 is connected at the exit end of the cooling coil 40 and conducts chilled air to horizontal heat exchanger 3. Pipe 24 provides for emergence of the cooled, dry, pressurized air from the heat exchanger 3 and leads to the exit valve 39. Drains provided with valves are shown at 33 for the heat exchanger 1, at 34 for the heat exchanger 1A and at 35 for the heat exchanger 3.

In operation, high temperature, pressurized air is admitted from a source not shown through the valve 19 optionally into the pre-cooler 2 where it is chilled by the cold air from heat exchanger 1 or IA, depending upon which of the solenoid valves, 8 and 9, are open or closed, circulating through the coil 40. The pre-cooled, pressurized air then emerges from the top of the precooler and alternately flows either through pipe 20 into heat exchanger 1 or pipe 21 into heat exchanger 1A, depending upon which of the solenoid valves, 8 and 9, are opened or closed. A continuous flow of cold, chilled air is, however, maintained from either the heat exchanger 1 or 1A through the pipe 22 where it is optionally used to pre-cool fresh, incoming, high temperature, pressurized air in the pre-cooler 40 and then is passed through the pipe 23 to the heat exchanger 3. In another embodiment of the invention, the pre-cooler 40 is dispensed with and the flow of chilled air from the heat exchanger 1 and 1A is directed immediately to the heat exchanger 3.

After final chilling in the heat exchanger 3 by means of cold refrigerant passed through the coils 38, the subzero, pressurized air emerges through pipe 24 and valve 39.

Cold refrigerant is provided to the heat exchangers l and 1A from the compressor 4 and the condenser 6 by means of pipes 25 and 27. Depending upon whether the solenoid valve is open or closed, cold refrigerant liquid passes through the expansion valve 16 to the heat exchanger coils 36 in the heat exchanger 1. Alternatively, the solenoid valve 10 is closed and solenoid 12 open to provide the flow of cold refrigerant liquid through the expansion valve 17 to the coil 37 in the heat exchanger 1A. Cold refrigerant gas emerges from the respective cooling coils of the heat exchangers 1 and 1A and is passed through the common tubing 28 back to the compressor 4. The refrigeration coils, 36 and 37, in the heat exchangers l and 1A through which cold refrigerant passes, provide the primary chilling of the high temperature air which is passed through the heat exchanger and also for the removal of condensables such as water vapor from the air. These condensables are subsequently removed from the heat exchangers without interruption of the flow of air through the system by passing hot refrigerant gas directly from the compressor 4 through the pipe 26 into the respective pairs of cooling coils, 36 and 37. Control of this flow of hot refrigerant gas to cause defrosting of the coils is effected by means of the solenoid valves, 11 and 13.

During the first-stage operation, while cold refrigerant liquid is being passed through the pipe 27 to the expansion valve 16 and then into the coil 36 of the heat exchanger 1, the solenoid valve 10 is open and the soleniod valve 11 is closed. Simultaneously, the solenoid valve 12 leading from heat exchanger 1A is closed but the solenoid valve 13 controlling the flow of hot refrigerant gas through the pipe 26 is open, permitting hot refrigerant gas to flow through the cooling coils 37 in the heat exchanger lA'. Condensables such as water are removed from the respective heat exchangers by means 0

valves

33 and 34 located at the bottom of the heat exchangers.

In the second stage of operation, both the solenoid 12 leading to the heat exchanger 1A and the solenoid 10 leading to the heat exchanger 1 are opened while both solenoids 11 and 13 are closed, thereby excluding the flow of hot, refrigerant gas from either heat exchanger 1 or 1A, while permitting the refrigeration coils 36 and 37 to be cooled simultaneously by the flow of cold refrigerant from the condenser 6 through the

expansion valves

16 and 17.

Once the cooling coils 37 of the heat exchanger 1A are sufficently chilled to prevent any carryover of moisture, the solenoid valve 8 is closed and solenoid valve 9 opened, thereby causing the flow of pressurized air from the pre-cooler 2 to be directed through pipe 21 into heat exchanger 1A. At the same time, solenoid valve 10 is closed to exclude cold refrigerant from the cooling coils of heat exchanger 1. Solenoid valve 13 remains closed while 11 is opened so that hot refrigerant gas from the compressor 4 defrosts the coils 36 of heat exchanger 1 in the same manner that heat exchanger 1A was previously cleared of condensates removed from the hot, pressurized air.

At the completion of the third stage where hot, pressurized air is chilled and dried in heat exchanger 1A while heat exchanger 1B is defrosted, the flow of hot refrigerant gas into the coils of heat exchanger 1 is terminated by closing solenoid valve 11. Simultaneously, solenoid valve 10 is opened causing a flow of cold refrigerant from condenser 6 through expansion valve 16 into the coils 36 of heat exchanger 1. The passage of air through the cooled heat exchanger 1A is continued during this pre-cooling of heat exchanger 1. Thus, the heat exchanger 1 is prepared for the return to the firststage operation whereby it cools and removes moisture from the pressurized hot air while the heat exchanger 1A is defrosted in its turn by hot refrigerant gas from the compressor 4.

The flow of cooled, dried air which emerges alternately from the two heat exchangers l and 1A flows on a continuous stream through pipe 22, either to the precooler 2 or directly to the heat exchanger 3 where final chilling to 60 F. takes place.

Cooling is effected in the heat exchanger 3 by means of the interconnected coils 38 through which passes cold refrigerant from the condenser 7. While removal of condensables such as water vapor from the heat exchanger 3 is not frequently. required, due to its having been previously eliminated from the air stream in the heat exchangers l and 1A, occasionally the solenoid valve 14 is closed and solenoid valve 15 opened so that, rather than cold refrigerant from the condenser, hot refrigerant gas from the compressor 5 is directed into the coils 38 to free them of accumulated frozen moisture.

Of course, it is within the scope of the present invention that several pairs of heat exchangers and their cooling and defrosting means as herein described, can be employed in series. Thus, the single heat exchanger 3 could be replaced with a second pair of heat exchangers the same as l and 1A and including cooling and defrosting means.

Activation of the various solenoid valves used to control the flow of gases and liquids is accomplished by means of conventional electrical circuits and relays which have not been shown. These circuits can involve largely manual control of the solenoids or can be extensively automated to respond to timed signals for changing cycles, for example.

The expansion valves shown at 1 6, 17, and 18 in H6. 4 meter the amount of liquid refrigerant entering the respective heat exchangers to maintain the predetermined temperature and pressure of the refrigerant gas. These valves are conventionally activated by means of sensors (not shown) which measure the temperature and pressure of the refrigerant gas after it has absorbed heat from the gas being cooled.

The refrigeration components of the present invention, including the compressors, condensers, expansion valves and refrigerant are, in themselves, conventional in design and operation.

It is claimed:

1. An apparatus for continuously cooling and drying a pressurized gas comprising in combination first and second heat exchanger means adapted for cooling and condensing moisture from said pressurized gas; a third heat exchanger means adapted for further cooling and condensing moisture from the gas cooled and dried in said first and second heat exchangers; first and second refrigeration means operatively connected with and each adapted to provide, in a cyclic system, to said first and second heat exchangers and to said third heat exchanger, respectively, separate flows of hot, pressurized refrigerant gas and cold refrigerant and to receive a return flow of cold refrigerant gas from said heat exchangers; said first and second heat exchanger means being operatively disposed in parallel and each provided with operatively connected means for regulating and circulating alternating flows of hot refrigerant gas and cold refrigerant from said first refrigeration means through itself and returning the gas to the refrigeration means; said third heat exchanger means also being provided with means for regulating and circulating alternate flows of hot refrigerant gas and cold refrigerant from said second refrigeration means through itself and returning the refrigeration gas to the refrigeration means; said first and second heat exchanger means each being further provided with means operatively connected for alternately circulating and regulating a separate flow of high temperature, pressurized gas through itself in heat exchange relationship with said cold refrigerant and then to said third heat exchanger means where further circulating and regulating means are provided for conducting said gas through said heat exchanger means in heat-exchange relationship with said cold refrigerant provided thereto.

2. The apparatus of claim 1 which further comprises preliminary heat exchanger means provided with means operatively connected with said first and second heat exchangers for circulating the flow of cooled, high pressurized gas from said first and second heat exchangers through itself and then to said third heat exchanger means; said preliminary heat exchanger means being further provided with operatively disposed means for passing the stream of high temperature, pressurized gas from its source in heat exchange relationship with said cooled gas and then to said first and second heat exchanger means.

3. The apparatus of claim 1 wherein said refrigeration means comprises in combination condenser means and compressor means operatively connected to provide a flow of hot, compressed refrigerant gas to said condenser means and alternately gas from said compressor through the cooling coils of the second of said heat exchangers to melt substances previously condensed from the high pressure gas;

2. Terminating the flow of hot refrigerant gas from the compressor through ssid cooling coils of the second heat exchanger and replacing it with a flow of cold refrigerant from the condenser while continuing to also pass said cold refrigerant through the coils of said first of said heat exchangers in heat exchange relationship with said high pressure gas introduced into said first heat exchanger; 3. Terminating the flow of high pressure gas into the first heat exchanger and directing it instead into said second heat exchanger where it is passed through in heat exchange relationship cooling coils containing cold refrigerant from said refrigerant source; simultaneously terminating the flow of cold refrigerant to the cooling coils of said first heat exchanger and passing instead through said coils hot refrigerant gas from the compressor to melt substances previously condensed from the high pressure gas; to each of'said first and second heat exchangers; said condenser means being further adapted to receive said hot, compressed refrigerant from said compressor means and to condense and cool it to a refrigerant liquid; means operatively connected to said condenser for regulating and circulating said refrigerant liquid to each of said first and second heat exchangers.

4. The apparatus of claim 1 wherein said hot, pressurized gas is air which emerges from said apparatus at a temperature below 0 F.

5. The apparatus of claim 4 wherein said air is cooled to F.

6. The apparatus of claim 1 which is operatively connected to provide cold, pressurized air to a device for blow-molding plastic articles.

7. A four-stage continuous process for cooling hot, high pressure gas comprising the steps of:

1. Introducing said high pressure gas into one of two parallel heat exchangers and passing it through the heat exchanger in heat exchange relationship with cooling coils containing a cold refrigerant supplied from a refrigerant source which includes a compressor and a condenser,simultaneously passing hot refrigerant 4. Terminating the flow of hot refrigerant gas from the compressor through the cooling coils of said first heat exchanger, and replacing it with a flow of cold refrigerant from the refrigerant source while continuing to also pass said cold refrigerant through the coils of said second heat exchanger in heat exchange relationship with said high pressure gas; said high pressure gas being removed from the two heat exchangers separately during each of the four steps of the process and being continuously combined into a common stream and cooled further to sub-zero temperature by being passed through a third heat exchanger provided with chilled refrigerant from a refrigeration source.

8. The process of claim 7 wherein the hot refrigerant gas is pre-cooled in a preliminary heat exchanger in heat exchange relationship with the stream of gas carried off continuously from said heat exchangers which is then directed to said third heat exchanger.

9. The process of claim 7 wherein said high pressure gas is air which emerges from said third heat exchanger UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,750,415 Dated August 7, 1973 Inventor(s) W-i 1 Fred S Peuchen: Glenwood K. Pass It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 3. s The apparatus of claim 1 wherein saidrefrigeration means comprises in combination condenser means and compressor means operatively connected to provide a flow of hot, compressed refrigerant gas to said condenser means and alternately to each of said first and second heat exchangers; said condenser means being further adapted to receive said hot, compressed refrigerant from said compressor means and to condense and cool it to a refrigerant liquid; means operatively connected to said condenser for regulating and circulating said refrigerant liquid to each of said first and second heat exchangers.

Claim 7. A four-stage continuous process for cooling hot,

high pressure gas comprising the steps of:

1. Introducing said high pressure gas into one of two parallel heat exchangers and passing it through the heat exchanger in heat exchange relationship with cooling coils containing a'cold refrigerant supplied from a refrigerant source which includes a compressor and a condenser simultaneously passing hot refrigerant gas from said compressor through the cooling coils of the second of said heat exchangers to melt substances previously condensed from the high pressure gas;

FORM PC4050 v I USCOMM-DC scam-ps9 W U.S. GOVERNMENT PRlNTlNG OFFICE I 9.9 0*38-33 v Page 2 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,750,415 Dated August 7, 1973 Inventor(s) Wilfred S. Peuchen; Glenwood K. Pase It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

(Cl. 7 contd) 2. Terminating the flow of hot refrigerant gas from the compressor through said cooling coils of the second heat exchanger and replacing it with a flow of cold regrigerant from thecondenser while continuing to also pass said cold refrigerant through the coils of said first of said heat exchangers in heat exchange relationship with said high pressure gas introduced into said first heat exchanger;

3. Terminating the flow of high pressure gas into the first heat exchanger and directing it instead into said second heat exchanger where it is passed through in heat exchange relationship cooling coils containing cold refrigerant from said refrigerant source; simultaneously terminating the flow of cold refrigerant to the cooling coils of said first heat exchanger and passing instead through said coils hot refrigerant gas from the compressor to melt substances previously condensed from the high pressure gas; 7

4. Terminating the flow of hot refrigerant gas from the compressor through the cooling coils of said first heat exchanger, and replacing it with a flow of cold refrigerant from the refrigerant source while continuing to also pass sadxd cold refrigerant through the coils of said second heat exchanger in heat exchange relationship with said high pressure gas;

FORM PO-105O (10-69) USCOMWDC 60.37am

* U.S. GOVERNMENT PRINTING OFFICE: {955 O-365334 K Pa 3 UNITED STATES PATENT OFFICE 98 CERTIFICATE OF CORRECTION 3,750,415 Dated August 7, 1973 Wilfred S. Peuchen; Glenwood K. Pase Patent No.

Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

(Cl. 7 contd) said high pressure gas being removed from the two heat exchangers separately during each of the four steps of the'process and being continuously combined into a common stream and cooled further to, sub-zero temperature by being passed through a third heat exchanger provided with chilled refrigerant from a refrigeration source.

Signed and sealed this 24th day of September 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM-DC 60376-P69 LLS. GOVERNMENT PRINTING OFFICE: 1969 0-366-334 F ORM PO-105O (10-69)

Claims

1. An apparatus for continuously cooling and drying a pressurized gas comprising in combination first and second heat exchanger means adapted for cooling and condensing moisture from said pressurized gas; a third heat exchanger means adapted for further cooling and condensing moisture from the gas cooled and dried in said first and second heat exchangers; first and second refrigeration means operatively connected with and each adapted to provide, in a cyclic system, to said first and second heat exchangers and to said third heat exchanger, respectively, separate flows of hot, pressurized refrigerant gas and cold refrigerant and to receive a return flow of cold refrigerant gas from said heat exchangers; said first and second heat exchanger means being operatively disposed in parallel and each provided with operatively connected means for regulating And circulating alternating flows of hot refrigerant gas and cold refrigerant from said first refrigeration means through itself and returning the gas to the refrigeration means; said third heat exchanger means also being provided with means for regulating and circulating alternate flows of hot refrigerant gas and cold refrigerant from said second refrigeration means through itself and returning the refrigeration gas to the refrigeration means; said first and second heat exchanger means each being further provided with means operatively connected for alternately circulating and regulating a separate flow of high temperature, pressurized gas through itself in heat exchange relationship with said cold refrigerant and then to said third heat exchanger means where further circulating and regulating means are provided for conducting said gas through said heat exchanger means in heat exchange relationship with said cold refrigerant provided thereto.

2. Terminating the flow of hot refrigerant gas from the compressor through said cooling coils of the second heat exchanger and replacing it with a flow of cold refrigerant from the condenser while continuing to also pass said cold refrigerant through the coils of said first of said heat exchangers in heat exchange relationship with said high pressure gas introduced into said first heat exchanger;

3. Terminating the flow of high pressure gas into the first heat exchanger and directing it instead into said second heat exchanger where it is passed through in heat exchange relationship cooling coils containing cold refrigerant from said refrigerant source; simultaneously terminating the flow of cold refrigerant to the cooling coils of said first heat exchanger and passing instead through said coils hot refrigerant gas from the compressor to melt substances previously condensed from the high pressure gas; to each of said first and second heat exchangers; said condenser means being further adapted to receive said hot, compressed refrigerant from said compressor means and to condense and cool it to a refrigerant liquid; means operatively connected to said condenser for regulating and circulating said refrigerant liquid to each of said first and second heat exchangers.

4. The apparatus of claim 1 wherein said hot, pressurized gas is air which emerges from said apparatus at a temperature below 0* F.

4. Terminating the flow of hot refrigerant gas from the compressor through the cooling coils of said first heat exchanger, and replacing it with a flow of cold refrigerant from the refrigerant source while continuing to also pass said cold refrigerant through the coils of said second heat exchanger in heat exchange relationship with said high pressure gas; said high pressure gas being removed from the two heat exchangers separately during each of the four steps of the process and being continuously combined into a common stream and cooled further to sub-zero temperature by being passed through a third heat exchanger provided with chilled refrigerant from a refrigeration source.

5. The apparatus of claim 4 wherein said air is cooled to -60* F.

9. The process of claim 7 wherein said high pressure gas is air which emerges from said third heat exchanger at about -60* F.