Compressor unit with control system

Abstract

A compressor unit intended for delivering a pressurised gaseous medium at a varying outlet flow volume to a consumer with varying load demands and comprises one or more rotors (K; 10, 11 ) forming one or more compressor stages and arranged to operate continuously at high speed thereby delivering a certain outlet flow volume, a drive motor (M; 19 ), a drive line assembly (N; 17, 18 ) mechanically coupling the compressor rotor or rotors (K; 10, 11 ) to the drive motor (M; 19 ), and a waste flow circuit connected to the outlet end of the compressor stages and incorporating at least one power recovery turbine (T R ; 22, 23 ) mechanically coupled to the drive line assembly (N; 17, 18 ), and one or more valves (V; 25, 34, 35 ) controlling the waste flow through the waste flow circuit in response to the actual load demand, wherein the power recovery turbine or turbines (T R ; 22, 23 ) are arranged to deliver power back to the drive line or drive lines (N; 17, 18 ) at consumer load demands smaller than the certain outlet flow volume delivered by the compressor rotor or rotors (K; 10, 11 ).

1 . Compressor unit for delivering a pressurized gaseous medium at a varying outlet flow volume to a consumer with varying load demands, comprising one or more rotors forming one or more compressor stages and arranged to operate continuously at high speed thereby delivering a certain output flow volume, a drive motor, and a drive line assembly mechanically coupling said compressor rotor or rotors to said drive motor, wherein a waste flow circuit is connected to the outlet end of said one or more compressor stages and arranged to receive at least a part of said certain outlet flow volume not covered by the actual load demand, said waste flow circuit comprises at least one power recovery turbine mechanically coupled to said drive line assembly, and at least one valve is arranged to control the waste flow through said waste flow circuit in response to the actual load demand, wherein said at least one power recovery turbine is powered by said waste flow and arranged to deliver power back to said drive line assembly at load demands smaller than said certain output flow volume.  
   
   
       2 . Compressor unit according to  claim 1 , wherein a control unit is provided to control the operation of said one or more valves in response to the actual load demand as well as the power supply to said drive motor to thereby maintain the rotation speed of said one or more compressor rotors at a high level at varying load demand.  
   
   
       3 . Compressor unit according to  claim 1 , wherein said one or more compressor rotors comprise two separate compressor rotors, said drive line assembly comprises two separate drive line sections, each one of said two compressor rotors is mechanically coupled to one of said drive line sections, said drive motor comprises a gas turbine having two turbine rotors each mechanically coupled to one of said drive line sections, said at least one power recovery turbine comprises two power recovery turbines, each one mechanically coupled to one of said drive line sections, said waste flow circuit is branched to both of said two power recovery turbines, and said one or more valves are arranged to control said waste flow through both of said two power recovery turbines.  
   
   
       4 . Compressor unit according to  claim 3 , wherein said two compressor rotors are connected in series to form a first compressor stage and a second compressor stage, and said waste flow circuit is connected at the output end of the second compressor stage.  
   
   
       5 . Compressor unit according to  claim 3 , wherein said two drive line sections are counterrotating.  
   
   
       6 . Compressor unit according to  claim 2 , wherein said one or more compressor rotors, comprise two separate compressor rotors, said drive line assembly comprises two separate drive line sections, each one of said two compressor rotors is mechanically coupled to one of said drive line sections, said drive motor comprises a gas turbine having two turbine rotors each mechanically coupled to one of said drive line sections, said at least one power recovery turbine comprises two power recovery turbines, each one mechanically coupled to one of said drive line sections, said waste flow circuit is branched to both of said two power recovery turbines, and said one or more valves are arranged to control said waste flow through both of said two power recovery turbines.  
   
   
       7 . Compressor unit according to  claim 6 , wherein said two compressor rotors are connected in series to form a first compressor stage and a second compressor stage, and said waste flow circuit is connected at the output end of the second compressor stage.  
   
   
       8 . Compressor unit according to  claim 6 , wherein said two drive line sections are counterrotating.