Method of operating a compressor and an apparatus therefor

Abstract

One or more compressor feed streams are passed to one or more inlets of a first compressor. Each compressor feed stream passes through a compressor feed valve. The one or more compressor feed streams are in the first compressor to provide a compressed discharge stream at the outlet of the first compressor, while monitoring for a first indicator of a blocked outlet event of the first compressor and instructing the closure of the compressor feed valves ( 12, 22, 32, 42 ) when the first indicator of the first compressor ( 100 ) blocked outlet event is detected. This provides a method of operating the compressor for the reduction of relief lead during a blocked outlet event, and an apparatus therefor.

1 . A method of operating a compressor, for the reduction of relief load during a blocked outlet event, comprising at least the steps of:
 (a) passing one or more compressor feed streams to one or more inlets of a first compressor, each compressor feed stream passing through a compressor feed valve;   (b) compressing the one or more compressor feed streams in the first compressor to provide a compressed discharge stream at the outlet of the first compressor;   (c) monitoring for a first indicator of a blocked outlet event of the first compressor;   (d) instructing the closure of the compressor feed valves upon detection of the first indicator of the first compressor blocked outlet event.   
     
     
         2 . The method of  claim 1 , wherein:
 in step (a) there are n compressor feed streams passing through n compressor feed valves, in which n is an integer greater than or equal to 1;   in step (c) a first monitoring device monitors for the first indicator of the blocked outlet event of the first compressor; and further comprising the step of:   (e) providing a first safety criterion in which m of the compressor feed valves fail to close in step (d), wherein m is an integer in the range of from 0 to n.   
     
     
         3 . The method of  claim 2 , further comprising the step of:
 (f) providing a pressure relief valve in fluid communication with the compressed discharge stream, said pressure relief valve set to open at a first set pressure, which is reached after the first indicator of the blocked outlet event of the first compressor;
 said pressure relief valve being connected to a flare system; and 
 wherein one or both of said pressure relief valve and said flare system is sized to accommodate at least the relief flow generated by the first safety criterion in which m of the compressor feed valves fail to close in step (d), wherein m is an integer in the range of from 1 to n. 
   
     
     
         4 . The method of  claim 1 , wherein step (a) comprises: passing a compressor first feed stream having a compressor first feed valve to a first inlet of the first compressor; and passing a compressor second feed stream having a compressor second feed valve to a second inlet of the first compressor. 
     
     
         5 . The method of  claim 1 , further comprising the steps of:
 (g) driving the first compressor with a first driver;   (h) monitoring, for a second indicator of a first compressor blocked outlet event with a second monitoring device; and   (i) instructing a reduction in the compression power of the first compressor when the second indicator of the first compressor blocked outlet event is detected.   
     
     
         6 . The method according to  claim 5 , wherein the reduction in the compression power of the first compressor is achieved by one or more of the group comprising: reducing the speed of the first driver and reducing the supply of power to the first driver. 
     
     
         7 . The method according to  claim 5 , wherein the first driver is a steam turbine and the reduction in the compression power of the steam turbine is achieved by one or more of the group comprising: reducing the flow of steam to the turbine and removing the cooling duty of a steam condenser of the steam turbine. 
     
     
         8 . The method according  claim 5 , wherein the first set pressure is reached after the first and second indicators of the first compressor blocked outlet event are reached. 
     
     
         9 . The method according to  claim 5 , wherein:
 (i) the first indicator and the second indicator are the same; or   (ii) the first indicator is selected such that it occurs before the second indicator; or   (iii) the second indicator is selected such that it occurs before the first indicator.   
     
     
         10 . The method of  claim 1 , in which the indicator of a first compressor blocked outlet event is selected from one or more of the group consisting of: a selected discharge pressure of the compressed discharge stream, a selected discharge temperature of the compressed discharge stream, a selected power of the first compressor, a selected suction pressure of the one of more compressor feed streams, and a selected suction temperature of the one or more compressor feed streams. 
     
     
         11 . The method according to  claim 1 , in which the first compressor is a refrigerant compressor, the two or more compressor feed streams are refrigerant feed streams and the compressed discharge stream is a compressed refrigerant discharge stream, further comprising the steps of:
 (j) cooling a stream derived from the compressed refrigerant discharge stream to provide a cooled refrigerant stream; and   (k) heat exchanging the cooled refrigerant stream, or a stream derived therefrom against a hydrocarbon stream or a further refrigerant stream to provide a cooled hydrocarbon stream.   
     
     
         12 . The method according to  claim 11 , wherein the hydrocarbon stream is a natural gas stream and the cooled hydrocarbon stream is a cooled natural gas stream, such as an at least partially liquefied natural gas stream. 
     
     
         13 . An apparatus for the reduction of relief load during a blocked outlet event of a compressor, comprising at least:
 a first compressor having an outlet for a compressed discharge stream and one or more inlets for one or more compressor feed streams, each compressor feed stream passing through a compressor feed valve; and   a first controller, the first controller in communication with a first device to provide a first indicator of a blocked outlet event of the first compressor, said first controller in further communication with each compressor feed valve, such that the first controller transmits a first signal to close each compressor feed valve upon detection of the first indicator of the blocked outlet event of the first compressor.   
     
     
         14 . The apparatus according to  claim 13 , wherein there are n compressor feed streams passing through compressor feed valves, in which n is an integer greater than or equal to 1; and further comprising:
 a pressure relief valve in fluid communication with the compressed discharge stream, said pressure relief valve being sized to open at a first set pressure, which is reached after the first indicator of the first compressor blocked outlet event; and   a flare system in fluid communication with the pressure relief valve, wherein one or both of pressure relief valve and the flare system is sized to accommodate at least the relief flow generated by a first safety criterion in which m of the compressor feed valves fail to close in step (d), wherein m is an integer in the range of from 1 to n.   
     
     
         15 . The apparatus according to  claim 13 , further comprising:
 a first driver mechanically connected to the first compressor to drive the first compressor; and   a second controller in communication with a second device, the second device to provide a second indicator of a first compressor blocked outlet event, such that said second controller transmits a third signal to reduce the compression power of the first compressor when the second indicator of a first compressor blocked outlet event is detected.