Regenerative compressed air/gas dryer
Patent References 1831644 3011589 Regenerating drying system Filtered environmental control system Dryer regeneration through heat of compression and pressure swing desorption Process and apparatus for purifying air to be distilled by adsorption Recovery of condensable organic compounds from inert gas streams laden Compressed natural gas dryer system and method of operation Pressure swing adsorption process for chlorine plant offgas Pressure swing adsorption heat recovery InventorsAssigneeApplicationNo. 09946657 filed on 09/05/2001US Classes:96/122, With recovery or separation means for desorbing fluid95/41, And solid sorption95/120, Heating or cooling95/126, By heating96/111, Concentration sensing means96/128, Compressor96/130, With means for regenerating solid sorbent96/143, With means regenerating solid sorbent96/144Gas contacting meansExaminersPrimary: Spitzer, RobertAttorney, Agent or FirmInternational ClassesB01D 53/04B01D 53/26 DescriptionBACKGROUND OF THE INVENTION This invention is generally directed to a novel regenerative compressed gas dryer system. More particularly, the invention contemplates a dryer and an integrated multi-stage compressor for drying a gas, such as air, which have been combined toenhance the total system performance versus prior art dryer-systems. Today, all dryers are designed to operate at the outlet of the compressor. With a heat of compression type dryer, the discharge temperature of the air at the outlet of the compressor is a critical item that determines the efficiency of thedryer. Many compressors have low discharge temperatures and thus the dryer that regenerates at the outlet is able to provide very limited performance. The present invention overcomes or minimizes the deficiencies of the prior art by connecting thedrier at an interstage of the compressor for regeneration, and by connecting the dryer at the outlet of the compressor for drying. In addition, traditionally, compressors and dryers are sold as distinct and separate products. Typically, the compressor is sold with a heat exchanger and a separator that are located at the outlet of the compressor. The dryer is considered tobe an accessory product and many times is not sold by the compressor manufacturer or compressor distributor. A difference between the prior art and the present invention is the marriage or integration of the compressor and the dryer to provide improvedperformance over prior art systems. Other features and advantages will become apparent upon a reading of the attached specification, in combination with a study of the drawings. OBJECTS AND SUMMARY OF THE INVENTION A general object of the present invention is to provide a novel regenerative compressed gas dryer system which includes an integrated multi-stage compressor and a dryer which has been combined to enhance the total system performance versus priorart dryer systems. An object of the present invention is to provide a novel regenerative compressed gas dryer system which connects the dryer interstage to one of the compressor stages between the compression stage and the heat exchanger for regeneration, andconnects the dryer to the outlet of the compressor for drying the gas. Another object of the present invention is to provide a novel regenerative compressed gas dryer system which can be used with a high pressure compressor. A further object of the present invention is to provide a novel regenerative compressed gas dryer system which has multiple stages with regeneration occurring interstage of any of the stages. Briefly, and in accordance with the foregoing, the present invention discloses a novel system for drying gas, such as air. The system includes a source of gas, such as air, to be dried, a multi-stage compressor having as inlet connected to thesource, and a dryer connected interstage to the compressor and to the outlet of the compressor. A dryer is connected interstage to the compressor between a compression stage and a heat exchanger of one of the compressor stages for regenerating a firstdesiccant filled tower. The dryer is also connected to the outlet of the compressor for drying the gas using a second desiccant filled tower. A communication structure can be activated to connect the first tower to the outlet of the compressor fordrying the gas using the first tower, and to connect the second tower interstage to the compressor for regeneration of the second tower. BRIEF DESCRIPTION OF THE DRAWINGS The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanyingdrawings, wherein like reference numerals identify like elements in which: FIG. 1 is a schematic diagram of a novel regenerative compressed gas dryer system which incorporates the features of a first embodiment of the invention; and FIG. 2 is a schematic diagram of a novel regenerative compressed gas dryer system which incorporates the features of a second embodiment of the invention. DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, specific embodiments with the understanding that the present disclosure is to be considered asexemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein. The present invention provides a novel regenerative compressed dryer system 20, 20a for drying a gas, such as air. The system 20, 20a includes an integrated multi-stage compressor 22 and a dryer 24, 24a which have been combined to enhance thetotal system performance versus prior art dryer systems. The compressor 22 used in the system 20, 20a of the present invention is a multi-stage compressor. Each stage in the compressor 22 includes a compression stage 26, a heat exchanger 28 and a moisture separator 30 or other like separator. Thedryer 24, 24a is connected interstage to one of the compressor stages between the compression stage 26 and the heat exchanger 28 for regeneration. The dryer 24, 24a is also connected to the outlet of the compressor 22 for drying the gas. The presentinvention can be used with a high pressure compressor which may have as few as two or as many as five or six stages. With this type of multi-stage compressor, the best location for interstage regeneration may be the third or fourth stage. Two embodiments of the present system are illustrated in the drawings. It is to be understood that the embodiments of the dryer 22, 22a shown and described herein are two examples of dryers than can be used. Other embodiments of dryers can beprovided so long as that regenerating tower is connected interstage so the compressor 22 and the drying tower is connected to the outlet of the compressor 22 and suitable communication means are provided for switching the communication between the dryerand the compressor 22 such that the functions of the towers can be reversed during operation. FIG. 1 illustrates a first embodiment of the system as used with a three stage compressor 22 wherein regeneration occurs interstage of the first stage. It isto be understood that multiple stages, such as six stages, can be provided in the compressor and the regeneration can occur interstage of any of the stage. FIG. 2 illustrates a second embodiment of the system as used with a three stage compressor 22wherein regeneration occurs interstage of the second stage. Again, it is to be understood the multiple stages, such as six stages can be provided in the compressor and the regeneration can occur interstage of any of the stages. In each embodiment, asource of gas that is to be dried, such as air, is connected to the inlet 32 of the compression stage 36 of the first stage of the multi-stage compressor 22. Attention is now directed to the embodiment of the system 20 shown in FIG. 1. Line 34 connects the compression stage 26 to valve 36 and to valve 38. Line 40 connects valve 36 to valve 42 and to valve 44. Line 46 connects valve 42 to a firstend of a tower 48, described in further detail herein, and to valve 50. Line 52 connects valve 50 to valve 54 and to valve 56. Line 58 connects valve 56 to valve 44 and to an end of a second tower 60. Line 82 connects valve 54 to the delivery outlet84 of the system 20. Line 62 connects the opposite end of tower 48 to valve 64 and to valve 66. Line 68 connects valve 64 to valve 70 and to valve 72. Line 74 connects valve 70 to valve 38 and to the inlet of the heat exchanger 28 of the first stage of thecompressor 22. Line 76 connects the opposite side of tower 60 to valve 72 and to valve 78. Line 80 connects the outlet of the compressor 22 to valve 78 and to valve 66. Each tower 48, 60 has a desiccant material therein that is used to remove moisture from the gas as it passes therethrough. A pressure gauge and a pressure relief valve are connected to each tower 48, 60. After the desiccant material becomessaturated and cannot efficiently remove moisture from the gas, the desiccant material needs to be regenerated. The lines as described herein are suitable for transporting high temperature gas therethrough. Temperature gauges, thermowells, a thermostat, temperature switches, pressure gauges, and pressure switches are also provided to monitor the system20. A control system (not shown) controls the flow of the gas through the system 20 as described herein. This embodiment of the dryer 22 can include suitable structure for a stripping operation or suitable structure for a cooling operation a can include suitable structure for a stripping and cooling operation. Now that the specifics of the system 20 have been described, the operation of the system 20 is described. As shown by the flow of gas as indicated by the arrows in FIG. 1, tower 48 is being regenerated and tower 60 is being used to removemoisture from the gas. By connecting the regenerating tower, shown as 48 in FIG. 1, of the dryer 24 to an interstage connection on the compressor 22, substantially better performance is achieved compared to prior art drying systems. Valves that are notdescribed as being used to pass gas therethrough an closed. When tower 48 is being regenerated, gas from the compression stage 26 of the first stage of the compressor 22 flows along line 34 through valve 36, along line 40, through valve 42, along line 46, through the one end of the tower 48, and throughtower 48. As the gas heated from the compression stage 26 flows through the tower 48, the desiccant is regenerated. The gas flows out the opposite end of the tower 48 along line 62, through valve 64, along line 68, through valve 70, along line 74 tothe inlet of the heat exchanger 28 of the first stage of the compressor 22. The gas then passes through the remainder of the compressor stages to the outlet of the compressor 22. Once the control system determines that the tower 48 has been sufficiently heated to regenerate the desiccant therein, valves 36 and 70 are closed and valve 38 is opened such that gas heated from the compression stage 26 is directed back to theheat exchanger 28 by flowing along line 34, through valve 38 and then along line 74. This bypasses the tower 48 and conserves the pressure loss in the compressor 22. When tower 60 is being used to remove moisture from the gas, gas from the outlet of the compressor 22 flows along line 80 through valve 78, along line 76, through one end of the tower 60 and through the tower 60. The desiccant in the tower 60dries the gas as it passes therethrough. The dried gas then flows along line 58, through valve 56, along line 52, through valve 54, along line 82 to the delivery outlet 84 of the system 20. Once the desiccant material in tower 60 becomes saturated and cannot efficiently remove moisture from the gas, the desiccant material needs to be regenerated. The control system is operated to open and close the appropriate valves such that thegas will now flow as described hereinafter. When tower 60 is being regenerated, gas from the compression stage 26 of the first stage of the compressor 22 flows along line 34, through valve 36, along line 40, through value 44, along line 58, through one end of the tower 60 and through thetower 68. As the gas heated from the compression stage 26 flows through the tower 60, the desiccant is regenerated. The gas flows out the opposite end of the tower 60 along line 76, through valve 72 along line 68, through valve 70, along line 74 to theinlet of the heat exchanger 28 of the first stage of the compressor 22. Once the control system determines that the tower 60 has been sufficiently healed to regenerate the desiccant therein, valves 36 and 70 are closed and valve 38 is opened such that gas heated from the compression stage 26 is directed back to theheat exchanger 28 by flowing along line 34, through valve 38 and then along line 74. Again, this bypasses the tower 48 and conserves the pressure loss in the compressor 22. At the end of regeneration, valves (not shown) can be activated to allow far"exhaust stripping" and/or "closed circuit cooling" to further improve dryer performance. When tower 48 is being used to remove moisture from the gas, gas from the outlet of the compressor 23 flows along line 80 through valve 66, along line 62, through one end of the tower 48 and through the tower 48. The desiccant in the tower 48dries the gas as it passes therethrough. The dried gas then flows along line 46, through valve 50, along line 52, through valve 54, along line 82 to the delivery outlet 84 of the system 20. As can be seen from the above description, the gas flows through the towers 48, 60 is opposite direction. Lines 46, 62, 58, 76 to be connected to the tower 48, 60 such that the gas flows through the towers 48, 60 in the same direction. Attention is now directed to the embodiment of the system 20a shown is FIG. 2. Line 200 connects the compression stage 26 to valve 202 and to valve 208. Line 206 connects valve 202 to valve 208 and to a first end of a tower 60a which isidentical in structure to tower 60 in FIG. 1. Line 210 connects valve 204 to valve 212 and to a first end of a tower 48a which is identical in structure to tower 48 in FIG. 1. Line 214 connects a second end of tower 60a to valve 216 and to valve 218. Line 220 connects valve 216 to valve 222 and to the inlet of the lieu exchanger 28. Line 224 connects valve 218 to the outlet of the compressor 22 and to valve 226. Line 228 connects valve 226 to valve 222 and to the second end of the tower 48a. Line 230 connects valve 212 to valve 208. Line 230 also connects' valves 212, 208 to an outlet 84a of the dryer 21a. An afterfilter is provided prior to the outlet 84a of the dryer 24a. Identical to that of the first embodiment each tower 48a, 60a has a desiccant material therein that is used to remove moisture from the gas as it passes therethrough. A pressure gauge and a pressure relief valve are connected to each tower 48a,60a. After the desiccant material becomes saturated and cannot efficiently remove moisture from the gas, the desiccant material needs to be regenerated. The lines as described herein are suitable for transporting high temperature gas therethrough. Temperature gauges, thermowells, a thermostat, temperature switches, pressure gauges, and pressure switches are also provided to monitor the system20a. A control system (not shown) controls the flow of the gas through the system 20a as described herein by using pilot gas bleed from line 230 by the structure shown at 232. Solenoids are used to activate the valves. In addition, a dew point monitoris provided by the structure shown at 234 to measure the moisture of the gas along line 230. Now that the specifics of the system 20a have been described, the operation of the system 20a is described. As shown by the flow of gas as indicated by the arrows in FIG. 2, tower 60a is being regenerated and tower 48a is being used to removemoisture from the gas. By connecting the regenerating tower, shown as 60a in FIG. 2, of the dryer 24a to an interstage connection on the compressor 22, substantially better performance is achieved compared to prior art drying systems. Valves that arenot described as being used to pass gas therethrough are closed. When tower 60a is being regenerated, gas from the compression stage 26 of the second stage of the compressor 22 flows along line 200 through valve 202, along line 206, through the one end at the tower 60a, and through tower 60a. As the gasheated from the compression stage 26 flows through the tower 60a, the desiccant is regenerated. The gas flows over the opposite end of the tower 60a along line 214, through valve 216, along line 220, to the inlet of the heat exchanger 28 of the secondstage of the compressor 22. When tower 48a is being used to remove moisture from the gas, gas from the outlet of the compressor 22 flows along line 224 through valve 226, along line 228, through one end of the tower 48a and through the tower 48a. The desiccant in the tower48a dries the gas as it passes therethrough. The dried gas then flows along line 210, through valve 212, along one 230 to the delivery outlet 84a of the system 20a. Once the desiccant material in tower 48a becomes saturated and cannot efficiently remove moisture from the gas, the desiccant material needs to be regenerated. The control system is operated to open and close the appropriate valves such that thegas will now flow as described hereinafter. When tower 48a is being regenerated, gas from the compression stage 26 of the second stage of the compressor 22 flows along line 200 through valve 204, along line 210, through the one end of the tower 48a, and through tower 48a. As the gasheated from the compression stage 26 flows through the tower 48a, the desiccant is regenerated. The gas flows out the opposite end of the tower 48a along line 228, through valve 222, along line 220, to the inlet of the heat exchanger 28 of the secondstage of the compressor 22. When tower 60a is being used to remove moisture from the gas, gas from the outlet of the compressor 22 flows along line 224 through valve 218, along line 214 through one end of the tower 60a and through the tower 60a. The desiccant in the tower60a dries the gas as it passes therethrough. The dried gas then flows along line 206, through valve 208, along line 230 to the delivery outlet 84a of the system 20a. As can be seen from the above description, the gas flows through the towers 48a, 60a in opposite directions. Lines 210, 228, 206, 214 can be connected to the towers 48a, 60a such that the gas flows through the towers 48a, 60a in the samedirection. It is to be understood that the embodiments of the dryer 22, 22a shown and described herein are two examples of dryers than can be used. Other embodiments of dryers can be provided so long as the regenerating tower is connected interstage to thecompressor 22 and the drying tower is connected to the outlet of the compressor 22 and suitable communication means are provided for switching the communication between the dryer and the compressor 22 such that the functions of the towers can be reversedduring operation. While preferred embodiments of the present invention are shown and described, it is envisioned that those skilled in the art may devise various modifications of the present invention without departing from the spirit and scope of the appendedclaims. * * * * * Field of SearchCOMPRESSING AND INDIRECT COOLING OF GASEOUS FLUID MIXTURE TO SEPARATEAnd solid sorption Water sorbed Heating or cooling By heating Concentration sensing means With recovery or separation means for desorbing fluid With heat exchange means And means for driving gas flow (e.g., pump, blower, compressor, etc.) Compressor With means for regenerating solid sorbent Plural canisters With means regenerating solid sorbent Gas contacting means Heat exchanger to regenerate |
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