Multistage turbocompressor

Abstract

A multistage turbocompressor is provided for compressing a process gas. The turbocompressor has includes a rotor and a casing. A gas seal is associated in each case with a first turbocompressor stage and a last turbocompressor stage for sealing a penetration of a rotor shaft through a wall of the at least one casing, against a respective stage inlet pressure or stage discharge pressure. The gas seals are connected to a sealing gas line via which they are supplied with a sealing gas. A pressure chamber on a pressure side of the gas seal of the last stage which provides sealing against pressure discharge to the environment is connected to a relief line which opens into a pressure sink. A plurality of sealing gas lines are connected to a sealing gas feed line in which at least one control valve is arranged between junctions of different sealing gas lines.

1 - 8 . (canceled) 
     
     
         9 . A multistage turbocompressor for compressing a process gas from an inlet pressure at an inlet of a first stage of the turbocompressor to a discharge pressure at an exit of a last stage of the turbocompressor, the turbocompressor comprising:
 at least one rotor having a rotor shaft;   at least one casing;   at least one gas seal associated in each case with at least the first stage and the last stage for sealing a penetration of the rotor shaft through a wall of the at least one casing, against a respective stage inlet pressure or stage discharge pressure, wherein the gas seals are connected to at least one sealing gas line via which they are supplied with a sealing gas;   wherein at least one pressure chamber on a pressure side of the at least one gas seal of the last stage which provides sealing against pressure discharge to the environment is connected to at least one relief line which opens into a pressure sink, and   wherein a plurality of sealing gas lines are connected to a sealing gas feed line in which at least one control valve is arranged between junctions of different sealing gas lines.   
     
     
         10 . The turbocompressor as claimed in  claim 9 , wherein the pressure sink is a discharge into a stage of the turbocompressor where a lower pressure exists, or into an inlet into a stage. 
     
     
         11 . The turbocompressor as claimed in  claim 9 , wherein an additional shaft seal is provided between the pressure chamber and a stage exit of the associated stage. 
     
     
         12 . The turbocompressor as claimed in  claim 9 , wherein a gas seal is provided at a plurality of stages and the respectively associated sealing gas line has a respective throttle which adjusts the sealing gas pressure to the sealing pressure. 
     
     
         13 . The turbocompressor as claimed in  claim 12 , wherein the control valve is arranged upstream of the sealing gas line, and wherein a provision is made for a control unit which is designed in such a way that when a first volumetric-flow limit value is fallen short of as a result of the respective throttle, the control valve opens. 
     
     
         14 . The turbocompressor as claimed in  claim 9 , wherein provision is made in the relief line for a control valve which is controlled by a control unit, the control unit being designed in such a way that the control valve opens if a second volumetric-flow limit value is fallen short of. 
     
     
         15 . The turbocompressor as claimed in  claim 14 , wherein the control unit is designed in such a way that the first volumetric-flow limit value is lower than the second volumetric-flow limit value. 
     
     
         16 . The turbocompressor as claimed in  claim 9 , wherein provision is made for a measuring device which determines differential pressure across the throttle and transmits the same to the control unit as a measurement for the volumetric flow.