Centrifugal compressor

Abstract

A centrifugal compressor includes one or more impellers, a casing which covers the one or more impellers, and a silencer. The casing includes a radial passage which guides a gas flowing out from a final stage impeller to a radially outer side, and an outlet scroll passage which communicates the radial passage with an outlet. The silencer includes a perforated plate in which a plurality of acoustic holes are formed, and a space forming body which forms an acoustic space connected to the plurality of acoustic holes. A first surface of the silencer opposite to a surface of the perforated plate defining the acoustic space forms at least part of an inner surface of the casing which defines the outlet scroll passage.

What is claimed is: 
     
         1 . A centrifugal compressor comprising:
 one or more impellers configured to rotate about an axis and to send a gas to a radially outer side of the axis;   a casing configured to cover the one or more impellers and to guide the gas from an inlet to an inside to discharge the gas from an outlet and having an outlet scroll passage which extends in a circumferential direction of the axis and communicates with the outlet; and   a silencer,   wherein the silencer includes a perforated plate in which a first surface and a second surface opposite to the first surface and a plurality of acoustic holes penetrating from the first surface to the second surface are formed, and a space forming body configured to form an acoustic space connected to the plurality of acoustic holes on a second surface side of the perforated plate, and   the first surface of the silencer forms part of an inner surface of the casing which defines the outlet scroll passage.   
     
     
         2 . The centrifugal compressor according to  claim 1 , wherein the first surface of the silencer forms only part of the inner surface of the outlet scroll passage. 
     
     
         3 . The centrifugal compressor according to  claim 1 , wherein:
 a first silencer and a second silencer are provided as the silencers,   the casing has a radial passage which guides the gas flowing out from a final stage impeller of the one or more impellers to the radially outer side and communicates with the outlet scroll passage,   the first surface of the first silencer forms part of the inner surface of the outlet scroll passage, and   the first surface of the second silencer forms part of an inner surface which defines the radial passage.   
     
     
         4 . The centrifugal compressor according to  claim 3 , wherein the first surface of the second silencer does not form an inner surface in an inner region including an end on a radially inner side of the axis but forms at least part of the inner surface in an outer region on the radially outer side from the inner region in the radial passage. 
     
     
         5 . The centrifugal compressor according to  claim 3 , wherein:
 a short distance silencer and a long distance silencer are provided as the second silencers,   the short distance silencer is disposed at a position closer to the final stage impeller than the long distance silencer in a radial direction of the axis, and   inner diameters of the plurality of acoustic holes of the short distance silencer are smaller than those of the plurality of acoustic holes of the long distance silencer.   
     
     
         6 . The centrifugal compressor according to  claim 1 , wherein at least part of the space forming body of the silencer is formed of the same material as that of the casing and integrally formed with the casing. 
     
     
         7 . The centrifugal compressor according to  claim 6 , wherein the perforated plate is formed of a material having a linear expansion coefficient larger than that of the casing. 
     
     
         8 . The centrifugal compressor according to  claim 1 , wherein the silencer has a drain hole which discharges a liquid in the acoustic space outside of the acoustic space. 
     
     
         9 . The centrifugal compressor according to  claim 8 , wherein:
 the drain hole has a first opening which opens in the first surface of the perforated plate, and a second opening which opens in the second surface of the perforated plate, and   a moisture absorbent is disposed in the drain hole.   
     
     
         10 . The centrifugal compressor according to  claim 1 , wherein inner diameters of the plurality of acoustic holes are 0.1 to 3.0 mm. 
     
     
         11 . The centrifugal compressor according to  claim 10 , wherein inner diameters of the plurality of acoustic holes are 0.2 to 1.0 mm. 
     
     
         12 . A centrifugal compressor comprising:
 one or more impellers configured to rotate about an axis and to send a gas to a radially outer side of the axis;   a casing configured to cover the one or more impellers and to guide the gas from an inlet to an inside to discharge the gas from an outlet and having an outlet passage which guides the gas flowing out from a final stage impeller of the one or more impellers to the outlet; and   a short distance silencer and a long distance silencer as silencers,   wherein each of the short distance silencer and the long distance silencer includes a perforated plate in which a first surface and a second surface opposite to the first surface and a plurality of acoustic holes penetrating from the first surface to the second surface are formed, and a space forming body configured to form an acoustic space connected to the plurality of acoustic holes on a second surface side of the perforated plate,   both the first surface of the short distance silencer and the first surface of the long distance silencer form part of an inner surface of the casing which defines the outlet passage,   a distance along the outlet passage from the final stage impeller to the short distance silencer is shorter than that along the outlet passage from the final stage impeller to the long distance silencer, and   inner diameters of the plurality of acoustic holes of the short distance silencer are smaller than those of the plurality of acoustic holes of the long distance silencer.   
     
     
         13 . The centrifugal compressor according to  claim 12 , wherein at least part of the space forming body of the silencer is formed of the same material as that of the casing and integrally formed with the casing. 
     
     
         14 . The centrifugal compressor according to  claim 13 , wherein the perforated plate is formed of a material having a linear expansion coefficient larger than that of the casing. 
     
     
         15 . The centrifugal compressor according to  claim 12 , wherein the silencer has a drain hole which discharges a liquid in the acoustic space outside of the acoustic space. 
     
     
         16 . The centrifugal compressor according to  claim 15 , wherein the drain hole has a first opening which opens in an inner surface of the space forming body which faces the acoustic space, and a second opening which opens in an outer surface of the casing. 
     
     
         17 . The centrifugal compressor according to  claim 15 , wherein:
 the drain hole has a first opening which opens in the first surface of the perforated plate, and a second opening which opens in the second surface of the perforated plate, and   a moisture absorbent is disposed in the drain hole.   
     
     
         18 . The centrifugal compressor according to  claim 12 , wherein inner diameters of the plurality of acoustic holes are 0.1 to 3.0 mm. 
     
     
         19 . The centrifugal compressor according to  claim 18 , wherein inner diameters of the plurality of acoustic holes are 0.2 to 1.0 mm. 
     
     
         20 . A centrifugal compressor comprising:
 one or more impellers configured to rotate about an axis and to send a gas to a radially outer side of the axis;   a casing configured to cover the one or more impellers and to guide the gas from an inlet to an inside to discharge the gas from an outlet and having a passage which guides the gas flowing in from the inlet to the outlet through the one or more impellers; and   a silencer,   wherein the silencer includes a perforated plate in which a first surface and a second surface opposite to the first surface and a plurality of acoustic holes penetrating from the first surface to the second surface are formed, a space forming body configured to form an acoustic space connected to the plurality of acoustic holes on a second surface side of the perforated plate, and a drain hole configured to discharge a liquid in the acoustic space to an outside of the acoustic space, and   the first surface of the silencer forms part of an inner surface of the passage.   
     
     
         21 . The centrifugal compressor according to  claim 20 , wherein the drain hole has a first opening which opens in an inner surface of the space forming body which faces the acoustic space, and a second opening which opens in an outer surface of the casing. 
     
     
         22 . The centrifugal compressor according to  claim 21 , wherein an opening area of the first opening is 20% or less of a total opening area of all the acoustic holes in a portion of the perforated plate which defines one acoustic space. 
     
     
         23 . The centrifugal compressor according to  claim 21 , wherein the silencer has a valve capable of partitioning a space in the drain hole from an outer space of the casing. 
     
     
         24 . The centrifugal compressor according to  claim 21 , wherein a moisture absorbent is disposed in the drain hole. 
     
     
         25 . The centrifugal compressor according to  claim 20 , wherein:
 the drain hole has a first opening which opens in the first surface of the perforated plate, and a second opening which opens in the second surface of the perforated plate, and   a moisture absorbent is disposed in the drain hole.   
     
     
         26 . The centrifugal compressor according to  claim 20 , wherein inner diameters of the plurality of acoustic holes are 0.1 to 3.0 mm. 
     
     
         27 . The centrifugal compressor according to  claim 26 , wherein inner diameters of the plurality of acoustic holes are 0.2 to 1.0 mm. 
     
     
         28 . A centrifugal compressor comprising:
 one or more impellers configured to rotate about an axis and to send a gas to a radially outer side of the axis;   a casing configured to cover the one or more impellers and to guide the gas from an inlet to an inside to discharge the gas from an outlet; and   a silencer,   wherein the casing has a passage configured to guide the gas flowing in from the inlet to the outlet through the one or more impellers,   the silencer includes a perforated plate in which a first surface and a second surface opposite to the first surface and a plurality of acoustic holes penetrating from the first surface to the second surface are formed, and a space forming body configured to form an acoustic space connected to the plurality of acoustic holes on a second surface side of the perforated plate,   the first surface of the silencer forms part of an inner surface of the casing which defines the passage,   at least part of the space forming body is formed of the same material as that of the casing and integrally formed with the casing, and   the perforated plate is formed of a material having a linear expansion coefficient larger than that of the casing.   
     
     
         29 . The centrifugal compressor according to  claim 28 , wherein inner diameters of the plurality of acoustic holes are 0.1 mm or more to 3.0 mm or less. 
     
     
         30 . The centrifugal compressor according to  claim 29 , wherein inner diameters of the plurality of acoustic holes are 0.2 mm or more to 1.0 mm or less.