Compressor Unit

Abstract

The invention relates to a compressor unit, in particular for underwater operation, wherein the stator of the motor is connected to a separate cooling means. It is an object of the invention to provide a cooling means for the stator of the electric motor, which cooling means firstly affords excellent operational reliability and secondly does not require any exchange of materials with the surroundings during operation. To this end, there is provision for the cooling means to be configured in such a way that there is a natural circulation of a cooling medium in the cooling means of the stator under operating conditions. One decisive advantage of the compressor unit according to the invention lies in the fact that the separate cooling means of the stator can be adapted precisely to the operating conditions of the latter and, in particular, firstly the high power loss and secondly the sensitivity of this component can be taken into consideration.

1 .- 14 . (canceled) 
   
   
       15 . An underwater compressor unit for compression of a pumping medium, comprising:
 a compressor and an electric motor having a stator and a rotor; and   a cooling arrangement separate from and connected to the motor stator where the cooling arrangement cools the motor stator and is constructed and arranged such that a cooling medium naturally circulates in the cooling arrangement of the stator during operation,   wherein the cooling arrangement has a condenser connected to the cooled stator via at least one feed line and at least one return line where the cooling medium circulates between the condenser, the return line, the stator and the feed line.   
   
   
       16 . The compressor unit as claimed in  claim 15 , wherein the cooling medium circulates within a closed circuit of the cooling arrangement. 
   
   
       17 . The compressor unit as claimed in  claim 16 , further comprising a pump arranged in the return line that pumps the cooling medium to produce a forced circulation of the cooling medium. 
   
   
       18 . The compressor unit as claimed in  claim 16 , wherein the cooling medium, in the closed circuit in the operating conditions and at the operating pressure, at least partially, changes to the gas phase during the heat absorption in the stator, and with the cooling medium changing to the liquid phase during the heat emission in the condenser. 
   
   
       19 . The compressor unit as claimed in  claim 18 , wherein the cooling medium is a hydrocarbon. 
   
   
       20 . The compressor unit as claimed in  claim 15 , wherein the compressor, the bearings of the compressor unit and the rotor of the motor are connected to a further cooling system and are cooled via the further cooling system. 
   
   
       21 . The compressor unit as claimed in  claim 20 , wherein the a cooling medium is a pumping medium. 
   
   
       22 . The compressor unit as claimed in  claim 21 , wherein the pumping medium is natural gas. 
   
   
       23 . The compressor unit as claimed in  claim 22 , wherein the cooling medium flows around the motor rotor. 
   
   
       24 . The compressor unit as claimed in  claim 23 , wherein walls of the cooling arrangement are adjacent to the cooling pumping medium and are designed for a maximum differential pressure between the pressure of the pumping medium and the pressure of the cooling medium in all operating states. 
   
   
       25 . The compressor unit as claimed in  claim 23 , wherein walls of the cooling arrangement are adjacent to the cooling pumping medium and are not designed for a maximum differential pressure between the pressure of the pumping medium and the pressure of the cooling medium in all operating states, and the pressure of the cooling medium is increased or decreased as a function of the pressure of the pumping medium. 
   
   
       26 . A method for operation of an underwater compressor unit for compression of a pumping medium, comprising:
 providing a compressor and an electric motor having a stator and a rotor;   providing a cooling arrangement separate from and connected to the motor stator where the cooling arrangement cools the motor stator and is constructed and arranged such that a cooling medium naturally circulates in the cooling arrangement of the stator during operation, wherein
 the cooling arrangement has a condenser connected to the cooled stator via at least one feed line and at least one return line where the cooling medium circulates between the condenser, the return line, the stator and the feed line, and 
 when the pressure of the pumping medium at the inlet varies, the cooling medium in the cooling arrangement is changed, and when the pressure of the pumping medium at the inlet is reduced, the operating pressure of the cooling medium in the cooling arrangement is also reduced. 
   
   
   
       27 . The method as claimed in  claim 26 , wherein, when the operating pressure of the cooling medium changes, the cooling medium is replaced with a different cooling medium.