Reflux gas compressor

Abstract

A positive displacement, transverse flow, internally refluxing, rotary gas compressor which operates on a constant volume, variable mass, near-isothermal compression cycle. The compressor includes a pair of involutely lobed, intermeshed impellers that sweep gas from an intake port through the compressor housing to a discharge port in constant volume displacement cavities that are defined by the lobes of the impellers and the compressor housing walls. The cavities are effectively sealed against both the intake and discharge ports over upstream interior housing sidewall portions that extend from the intake port over an angle at least as great as the angle between adjacent lobes of the impellers. Downstream therefrom the interior housing sidewalls are spaced radially from the rotating impellers so as to allow limited reflux counterflow of discharge gas back into the advancing displacement cavities. The refluxing gas isentropically expands into the constant volume displacement cavities so that the pressure of the gas contained in the displacement cavities approaches that of discharge. The final pressure increase with accompanying volume reduction into discharge is gained by adiabatic compression at a low pressure ratio as each cavity opens into discharge. The resulting process is noncontaminating and more energy efficient than compression by volume reduction alone.

1 . A positive displacement, transverse flow, internally refluxing rotary gas compressor comprising:
 a housing having two opposing end walls and two mutually opposing interior sidewalls, said housing including a gas intake port between said interior side walls at one end of said housing and a gas discharge port between said interior sidewalls at the opposite end of said housing from said intake port;   first and second involutely lobed impellers journalled within said housing for rotation in opposite directions about parallel axes of rotation extending transversely from said end walls, said impellers being spaced from and intermeshed with one another so as to form a high impedance gas seal between said impellers while said impellers are rotated in opposite directions, and each of said impellers having from four to nine radially extending lobes that are equally spaced angularly with respect to one another and which thereby define an angular sector between adjacent lobes, and with adjacent lobes of said impellers and said end walls and said interior sidewalls of said housing together defining displacement cavities in which parcels of intake gas are swept through said housing from said intake port to said discharge port;   said opposing interior sidewalls each having an upstream sidewall portion and a downstream sidewall portion, said upstream sidewall portions being substantially cylindrical and having cylindrical axes that are coaxial with the respective axes of rotation of said impellers, said upstream sidewall portions having radii of curvature sized so as to form an effective gas seal with said lobes of said impellers and thereby prevent significant backflow of compressed discharge gas while also allowing said lobes to sweep gas through said housing, and said upstream sidewall portions extending from said intake port over an angular sector at least as great as said angular sector between adjacent lobes of said impellers; and   said downstream sidewall portions of said opposing interior sidewalls extending upstream from said discharge port over an angular sector at least as great as said angular sector between adjacent lobes of said impellers, and being sized radially so as to allow a controlled amount of reflux counterflow of compressed discharge gas into the displacement cavities formed between adjacent lobes of said impellers by controlled flow of compressed discharge gas between said lobes of said impellers and said downstream sidewall portions of said housing.   
   
   
       2 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein each of said involutely lobed impellers has four lobes, and wherein said upstream sidewall portions extend over an angular sector of at least approximately ninety degrees downstream from said intake port. 
   
   
       3 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein each of said involutely lobed impellers has five lobes, and wherein said upstream sidewall portions extend over an angular sector of at least approximately seventy two degrees downstream from said intake port. 
   
   
       4 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein each of said involutely lobed impellers has six lobes and wherein said upstream sidewall portions extend over an angular sector of at least approximately sixty degrees downstream from said intake port. 
   
   
       5 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein each of said involutely lobed impellers has seven lobes and wherein said upstream sidewall portions extend over an angular sector of at least approximately fifty two degrees downstream from said intake port. 
   
   
       6 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein each of said involutely lobed impellers has eight lobes and wherein said upstream sidewall portions extend over an angular sector of at least approximately forty five degrees downstream from said intake port. 
   
   
       7 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein each of said involutely lobed impellers has nine lobes and wherein said upstream sidewall portions extend over an angular sector of at least approximately forty degrees downstream from said intake port. 
   
   
       8 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least twice the angular sector between adjacent lobes of each of said impellers. 
   
   
       9 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 4  wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least one hundred ten degrees. 
   
   
       10 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein said downstream sidewall portions are cylindrical in shape and have a radius of curvature greater than that of said upstream sidewall portions. 
   
   
       11 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein said downstream sidewall portions are each of progressively increasing radius with regard to the axes of rotation of said impellers, from said upstream sidewall portion to said discharge port. 
   
   
       12 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 4  wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least one hundred eighty degrees. 
   
   
       13 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 3  wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least one hundred forty degrees. 
   
   
       14 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 5  wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least one hundred four degrees. 
   
   
       15 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 6  wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least ninety degrees. 
   
   
       16 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 7  wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least eighty degrees. 
   
   
       17 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 10  further including a transition sidewall portion between said upstream and downstream sidewall portions of said interior sidewalls. 
   
   
       18 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 11  further including a transition sidewall portion between said upstream and downstream sidewall portions of said interior sidewalls. 
   
   
       19 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 12  wherein said downstream sidewall portions are each of progressively increasing radius with regard to the axes of rotation of said impellers, from said upstream sidewall portion to said discharge port. 
   
   
       20 . The positive displacement, transverse flow, internally refluxing, rotary gas compressor defined in  claim 1  wherein said upstream sidewall portions extend from said intake port over an angular sector at least twice as great as the angular sector between adjacent lobes of said impellers, and wherein said downstream sidewall portions each extend upstream from said discharge port over an angular sector of at least twice the angular sector between adjacent lobes of each of said impellers.