Integrated motor-compressor unit having a cooling circuit and a depressurization system configured to reduce pressure of the cooling fluid

Abstract

An integrated motor-compressor unit comprising a motor and a compressor coupled to said motor via a rotatable shaft and mounted in a single common housing configured to circulate a cooling fluid in a cooling circuit, wherein the integrated motor-compressor unit comprises a depressurization system configured to depressurize the pressure of the motor.

What is claimed is: 
     
         1 . A motor-compressor unit, comprising:
 a motor;   a first compressor coupled to the motor, the first compressor having a main suction inlet and a discharge outlet;   a cooling circuit comprising cooling conducts and hot conducts; and   a depressurization system coupled to the cooling circuit and configured to depressurize fluid in the cooling circuit to create a pressure drop of at least 10 bars, the depressurization system comprising:
 an expansion device coupled to the cooling conducts; and 
 a second compressor coupled to the hot conducts and configured to recover suction pressure, 
   wherein the expansion device is configured to receive working fluid via the main compressor suction inlet of the first compressor and to transmit expanded cooled working fluid into the cooling conducts of the cooling circuit,   wherein the cooling circuit circulates the expanded cooled working fluid from the cooling conducts to the hot conducts, the cooling circuit arranged so that the expanded cooled working fluid passes in proximity to the motor and the first compressor as the expanded cooled working fluid transits from the cooling conducts to the hot conducts, and   wherein the second compressor is configured to receive the expanded cooled working fluid from the hot conducts after having cooled the motor, to compress the expanded hot working fluid, and to then deliver the working fluid back to the main compressor suction inlet.   
     
     
         2 . The motor-compressor unit according to  claim 1 , wherein the expansion device is an expansion wheel. 
     
     
         3 . The motor-compressor unit according to  claim 2 , wherein the depressurization system further comprises a cooler. 
     
     
         4 . The motor-compressor unit according to  claim 1 , wherein the second compressor is a low pressure compressor. 
     
     
         5 . An integrated motor-compressor unit, comprising:
 a motor;   a first compressor coupled to the motor via a rotatable shaft, the first compressor having a main suction inlet and a discharge outlet;   a single common housing enclosing the motor, the first compressor, and the rotatable shaft;   a cooling circuit disposed in the single common housing and   a depressurization system configured to depressurize fluid in the cooling circuit to create a pressure drop of at least 10 bars, the depressurization system comprising:
 an expansion device, and 
 a second compressor configured to recover suction pressure, 
   wherein the expansion device is comprises a cooling expansion valve that is coupled to the main compressor suction inlet of the first compressor to receive working fluid downstream of the cooling expansion valve and to transmit expanded cooled fluid to the cooling circuit of the integrated motor-compressor unit, and   wherein the auxiliary compressor is configured to receive cooling fluid after having cooled the motor, to compress cooling fluid, and to then deliver the working fluid back to the main compressor suction inlet.   
     
     
         6 . The integrated motor-compressor unit according to  claim 5 , wherein the expansion wheel is mounted on a motor shaft end and the second compressor is mounted on a compressor shaft end. 
     
     
         7 . The integrated motor-compressor unit according to  claim 5 , wherein the expansion of the working fluid is created by first compressor leakages that occur during operation and that are compressed by the second compressor. 
     
     
         8 . The integrated motor-compressor unit according to  claim 5 , wherein the depressurization system also comprises a cooler in thermal contact with the cooling circuit. 
     
     
         9 . The integrated motor-compressor unit according to  claim 5 , wherein the depressurization system comprises a blower device mounted upstream of the first compressor. 
     
     
         10 . The integrated motor-compressor unit according to  claim 5 , wherein the depressurization system further comprises a third compressor configured to compensate for compressor gas leakages. 
     
     
         11 . The integrated motor-compressor unit according to  claim 5 , wherein the depressurization system also comprises a cooler in thermal contact with the cooling circuit after or before the blower device. 
     
     
         12 . The integrated motor-compressor unit according to  claim 5 , wherein the rotatable shaft is supported at each end by at least one bearing.