Patent Document

FIELD OF THE INVENTION 
     The present invention relates generally to gas drying systems. More particularly, the present invention relates to a system that uses fluid heated by a compressor to preheat a fluid used to regenerate adsorbent in an adsorption chamber in a gas drying system. 
     BACKGROUND OF THE INVENTION 
     Industrial systems, particularly pneumatic systems require dry air or another dry gas. If regular ambient air was used there may be too much humidity in it causing corrosion and lack of desired performance. Typical air or other gas drying systems configured to provide dry gas for industrial uses often include adsorption chambers containing an adsorbent material. Over the course of the usage of the system, the adsorbent material may become saturated and cannot effectively or efficiently remove moisture from a gas. 
     As such, the adsorption chamber may need to be taken off-line and the adsorbent regenerated using a purge gas. Often, drying systems may use two or more different adsorption chambers in order for one adsorption chamber to be used drying the gas while the other adsorption chamber (or adsorption chambers) is(are) being regenerated. In such systems, valves may be used to take the adsorption chambers on and off-line as needed and to flow a purge gas through the off-line adsorption chamber to assist in regeneration of the adsorbent contained in the adsorption chamber. 
     In many instances the purge gas may be heated prior to entering the off-line adsorption chamber because heated purge gas may be more effective than non-heated purge gas in regenerating the adsorbent. In some instances, the systems may have a compressor which compresses the gas be dried. Compressors are well known to generate heat and it would be efficient if the heat from the compressor could be used to also heat the purge gas. 
     In some instances, a gas that is being compressed in the compressor has been used as a purge gas. However, in such systems care is taken to ensure that the compressor is a non-lubricated compressor in order to ensure contaminants such as lubricants do not find their way into the purge gas. Such contaminants can contaminate the adsorbent being regenerated causing the adsorbent to lose or reduce its effectiveness. 
     Accordingly, it is desirable to provide a method and apparatus that may use heat generated by the compressor without necessarily using a compressed gas by the compressor as a purge gas thereby avoiding some of the drawbacks of using compressed gas by the compressor as a purge gas. 
     SUMMARY OF THE INVENTION 
     The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments a method and apparatus that may use heat generated by the compressor without necessarily using a gas compressed by the compressor as a purge gas thereby avoiding some of the drawbacks of using compressed gas by the compressor as the purge gas. 
     In accordance with one embodiment of the present invention, a system for regenerating an adsorbent in an off-line adsorption chamber is provided. The system includes: a heat exchanger configured to exchange heat from a first fluid coming from a compressor and a second fluid, wherein only a portion of the first fluid flows through the heat exchanger when the first fluid is gas; a conduit providing fluid communication between the second fluid exiting the exchanger and an off-line adsorption chamber; an adsorbent in the off-line adsorption chamber; and an outlet to the off-line adsorption chamber configured to outlet the second fluid from the off-line adsorption chamber. 
     In accordance with another embodiment of the present invention, a method of preheating a purge fluid supplied to an off-line adsorption chamber is provided. The method includes: flowing the purge fluid through a heat exchanger; flowing a heated fluid from a compressor through the heat exchanger thereby heating the purge fluid wherein only a portion of the heated fluid flows through the heat exchanger when the heated fluid is gas; and flowing the purge fluid through an off-line adsorption chamber containing an adsorbent. 
     In accordance with yet another embodiment of the present invention, a system for regenerating an adsorbent in an off-line adsorption chamber is provided. The system includes: means for exchanging heat between fluids configured to exchange heat from a first fluid coming from a compressor and a second fluid, wherein only a portion of the first fluid flows through the means for exchanging heat when the first fluid is gas; a conduit providing fluid communication between the second fluid exiting the means for exchanging heat and an off-line adsorption chamber; means for desorbing moisture from the off-line adsorption chamber; and an outlet to the off-line adsorption chamber configured to outlet the second fluid from the off-line adsorption chamber. 
     There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
     As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a gas drying system using compressor heat to preheat a gas used to regenerate an adsorbent in the drying system according to an embodiment. 
         FIG. 2  is a schematic diagram of a gas drying system using compressor heat to preheat a gas used to regenerate an adsorbent in the drying system according to an another embodiment. 
         FIG. 3  is a schematic diagram of a gas drying system using compressor heat to preheat a gas used to regenerate an adsorbent in the drying system according to an another embodiment. 
         FIG. 4  is a schematic diagram of a gas drying system using compressor heat to preheat a gas used to regenerate an adsorbent in the drying system according to an another embodiment. 
         FIG. 5  is a schematic diagram of a gas drying system using compressor heat to preheat a gas used to regenerate an adsorbent in the drying system according to an another embodiment. 
         FIG. 6  is a schematic diagram of a gas drying system using compressor heat to preheat a gas used to regenerate an adsorbent in the drying system according to an another embodiment. 
         FIG. 7  is a flowchart showing steps accomplished according to a method consistent with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a system and process for removing a constituent from a gas stream, using an adsorbent fractionator (i.e. a dryer) employing a purge gas source and a heat exchanger to recover heat from the compressor, either directly from the hot compressed discharge gas or indirectly from the hot compressor coolant. 
     An embodiment of the present inventive apparatus is illustrated in  FIG. 1 .  FIGS. 1 through 6  illustrate gas dryer systems  10  of various embodiments. The embodiments shown in  FIGS. 1 through 6  are similar with the exception of the location or absence of the blower.  FIG. 1  will be explained in detail. Descriptions of the differences between the other figures and  FIG. 1  will also be described. However, detailed descriptions of each of the other figures will not be made in detail as they will, for the most part, be repetitive with to respect  FIG. 1 . 
       FIG. 1  shows a drier system  10 . The dryer system  10  includes a compressor  12 . Gas is compressed in the compressor  12 . As a result of the compression heat is generated within the compressor  12  and the gas. The gas exits the compressor  12 . Part of the gas is bled off into a conduit  14  while the remainder of the hot gas flows through conduit  13  and flows directly to the inlet of the trim cooler  20 . 
     The gas in the conduit  14  flows into a heat exchanger  16 . Ambient air is drawn into a purge air filter  15  and is filtered and then also flows into the heat exchanger  16 . In the heat exchanger  16 , heat from the hot gas coming from conduit  14  flows into the second gas that has been filtered through the inlet filter  15 . The hot gas from conduit  14  is cooled somewhat and flows out of the heat exchanger  16  and into the conduit  18 . It then flows into a trim cooler  20  where it is further cooled by exchanging heat with a fluid flowing through inlet  22  through the trim cooler  20  and out trim cooler outlet  24 . 
     The gas then flows through conduit  26  into a moisture separator  28 . Moisture is condensed and separated from the gas and flows through an outlet  29  where it may be disposed of such as through a municipal sewer system or any other suitable disposable system. The gas then flows out of the outlet  30 . 
     Valves  32  and  34  dictate which adsorption chamber  33  or  40  gas exiting the moisture separator will throw flow through. Typically one of the adsorption chambers  33  or  40  is operational and is drying the gas while the other adsorption chamber is taken off-line and is purged in order to regenerate the adsorbent material contained within the adsorption chamber  33  or  40 . As shown in  FIG. 1 , valve  34  is in the open position while valve  32  is in the closed position. Therefore the fluid flows through valve  34  and past purge exhaust valve  36  and depressurization valve  38  and into the adsorption chamber  40 . Had the situation been reversed and  34  been closed and  32  been open then the gas would have flowed into adsorption chamber  33  and adsorption chamber  40  would of been off-line and undergoing a purge operation. As the gas flows through the adsorption chamber  40  and over the adsorbent material  41  the gas is dried and flows out of the adsorption chamber into conduit  42 . 
     The gas flows past valve  44  and the dry gas stripping re-pressurization circuit  46 . The dry gas stripping and re-pressurization circuit  46  includes valves  48 ,  50 ,  52 , and  54 . These valves may be configured as shown or in any other manner to allow dry gas coming out of either adsorption chamber  40  or  33  to go to conduit  60  to the dry gas user or storage  62 . The dry gas stripping supply in re-pressurization circuit  46  may also be set or configured to bleed some of the dry gas from conduit  42  out and sent it to the off-line adsorption chamber (adsorption chamber  33  as shown in  FIG. 1 ) as part of a regeneration process for the off-line adsorption chamber  33 . Valves  56  and  58  prevent or allow processed gas to enter the off-line adsorption chamber. 
     The regeneration of the off-line adsorption chamber  33  is accomplished by the ambient air drawn into the system  10  through the purge inlet filter  15 . As mentioned above, the purge air flows through the heat exchanger  16  and is heated by heat from fluid coming into the heat exchanger  16  from conduit  14 . After picking up heat in the heat exchanger  16  the purge fluid flows through conduit  64  due to action of the blower  66 . The purge fluid may be additionally heated if needed by a trim heater  68 . The purge fluid then flows through valve  70  into the off-line adsorption chamber  33  where it will regenerate adsorbent  41  in the off-line adsorption chamber  33 . In embodiments where the off-line adsorption chamber is adsorption chamber  40  and not  33 , then valve  70  will be shut and valve  44  will be open to allow the purge fluid to flow through adsorption chamber  40 . The dry gas stripping supply in re-pressurization circuit  46  is configured such that valve  52  is closed so that no stripping flow joins the purge fluid flowing into one of the adsorption chambers  33  and  40 . As shown in  FIG. 1 , valve  44  is closed and valve  70  is open thereby forcing the purge fluid to flow through the off-line adsorption chamber  33 . Once a purge fluid has flowed through off-line adsorption chamber  33  and flows out of the off-line adsorption chamber  33  and through valve  72  where it may be vented to the ambient conditions or may undergo any further operations if desired. 
       FIG. 2  illustrates a system  10  where the blower  66  is not located in front of the trim heater  68  as described in  FIG. 1 . Rather the blower  66  is located downstream of the adsorption chambers  33  and  40 . As shown in  FIG. 2 , the blower  66  is located downstream of the valves  72  and  36 . The blower  66  still provides the function of moving the purge fluid through the system  10 . 
       FIG. 3  illustrates a system  10  where the blower  66  is located upstream from the heat exchanger  16 . The blower  66  is able to draw in ambient air through the purge inlet filter  15  and provide pressure to move it through the heat exchanger  16 , the conduit  64 , the trim heater  68 , and either of the adsorption chambers  33  and  40  depending on which adsorption chamber is off-line. 
       FIG. 4  illustrates a system  10  where there is no blower as part of the system  10 . Rather the purge fluid is obtained from an external source and may or may not be ambient air. The purge gas supply  17  directly inputs the purge gas into the heat exchanger  16 . The purge source or gas supply  17  provides the pressure to move the purge gas through the system  10 . In some embodiments, a blower may be associated with the external purge gas supply  17 . 
       FIG. 5  illustrates a system  10  where a jet compressor  76  is used rather than a blower  66 . The jet compressor  76  may be powered by dried fluid containing conduit  60 . Ambient air may be drawn through the purge inlet filter  15  by suction created by the jet compressor  76 . The jet compressor  76  also provides pressure to move the purge air through the system  10 . In some embodiments, the conduit  60  may merely connect to the heat exchanger  16  without components  15  and  76 . In such embodiments the pressure in conduit  60  will provide motive force to move gas through the regeneration loop. Thus, components  15  and  76  are optional. 
       FIG. 6  illustrates a system where the fluid obtained from the compressor is not a compressed gas output from the compressor but rather cooling fluid used by the compressor. Heated compressor coolant from a compressor coolant supply  77  flows into the heat exchanger  16 . Heat flows out of the heated compressor coolant in the heat exchanger  16  into purge air in the heat exchanger  16  the coolant then flows out of the heat exchanger  16  into conduit  78  and back to a coolant reservoir  80  associated with the compressor. While the blower  66  is illustrated to be located between the purge inlet filter  15  and the heat exchanger  16  one of ordinary skill in the art after reviewing this disclosure will understand that the blower  66  could be located at any of the places discussed above or substituted for any of the other purge gas pressure systems described above or any other suitable system or apparatus for providing a motive force for the purge fluid. 
     One of ordinary skill in the art after reviewing this disclosure will understand that the specific configurations of valves, conduit, and other apparatus described herein are meant to be exemplary only and do not limit embodiments accordance with the present disclosure. Other suitable configurations may also be used in accordance with the embodiment. One of ordinary skill in the art will also understand that some of the structures described herein, are optional and may be omitted and still be in accordance with the present disclosure. 
       FIG. 7  illustrates a method of steps that may be accomplished in accordance with the present disclosure. It will be assumed that prior to the method described below the off-line adsorption chamber is first depressurized in preparation for regeneration. In step S 1 , flow of a first fluid from a compressor enters into a heat exchanger. This first fluid may be, in some embodiments, a compressed gas outputted from the compressor or as described above it may be a coolant that is been heated by the operation of the compressor. Optionally, a second fluid which may be, but not limited to, ambient air may be filtered. At step S 3  the second fluid flows through the heat exchanger. At step S 4  heat moves from the first fluid into the second fluid in the heat exchanger. Optionally, additional heat may be added to the second fluid by a trim heater or other means in step S 5 . Optionally, a blower or any other suitable apparatus provides a motive force to move the second fluid through the system. At step S 7  the second fluid flows through an off-line adsorption chamber and, at step S 8  the second fluid flows over and adsorbent in the off-line adsorption chamber thereby regenerating the adsorbent. Optionally, at step S 9  a small amount of dried first fluid may also flow over the adsorbent in the off-line adsorption chamber to further regenerate the adsorbent. The small amount of dried first fluid may flow into the off-line adsorption chamber prior to, concurrently with, or after the second fluid flows through the adsorption chamber. The optional flow of the first fluid after it has been dried through the off-line adsorption chamber may also provide partial cooling of the adsorbent in the adsorption chamber. After the adsorption chamber has undergone the purge process the adsorption chamber may be re-pressurized to line pressure in the adsorption chamber may remain in a standby state until is put back online. 
     The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Technology Category: 7