Compression train including two centrifugal compressors and lng plant including two centrifugal compressors

Abstract

The compression train includes an engine, a first centrifugal compressor driven by the engine and a second centrifugal compressor driven by the engine; the first centrifugal compressor is housed inside one case; the second centrifugal compressor is housed inside one case; the first centrifugal compressor has a first inlet fluidly connected to a line of high molecular weight gas, in particular higher than 40; the second centrifugal compressor has a second inlet fluidly connected to a line of low molecular weight gas, in particular between 20 and 30; the second centrifugal compressor is arranged to provide a compression ratio higher than 10:1.

What is claimed is: 
     
         1 . A compression train comprising an engine, a first centrifugal compressor driven by the engine and a second centrifugal compressor driven by the engine;
 wherein the first centrifugal compressor is housed inside one case;   wherein the second centrifugal compressor is housed inside one case;   wherein the first centrifugal compressor has a first inlet fluidly connected to a line of high molecular weight gas;   wherein the second centrifugal compressor has a second inlet fluidly connected to a line of low molecular weight gas; and   wherein the second centrifugal compressor is arranged to provide a compression ratio higher than 10:1.   
     
     
         2 . The compression train of  claim 1 ,
 wherein the high molecular weight gas is propane,   wherein the low molecular weight gas is a mixed-refrigerant gas.   
     
     
         3 . The compression train of  claim 1 , wherein the engine is an electric motor or a steam turbine or a gas turbine. 
     
     
         4 . The compression train of  claim 3 , wherein the engine is a high speed engine. 
     
     
         5 . The compression train of  claim 1 , wherein the second centrifugal compressor is mechanically connected to the first centrifugal compressor through a gear box having a transmission ratio higher than 2:1. 
     
     
         6 . The compression train of  claim 5 , wherein the engine is an electric motor or a steam turbine or a gas turbine, in particular an aeroderivative gas turbine. 
     
     
         7 . The compression train of  claim 5 , wherein the engine is a low speed engine. 
     
     
         8 . The compression train of  claim 1 , comprising further an auxiliary engine. 
     
     
         9 . The compression train of  claim 1 ,
 wherein the second centrifugal compressor comprises a first set of impellers and a second set of impellers;   the impellers of the first set being centrifugal and unshrouded; and   the impellers of the second set being centrifugal and shrouded.   
     
     
         10 . The compression train of  claim 1 ,
 wherein the second centrifugal compressor comprises a first set of impellers and a second set of impellers;   the impellers of the first set being centrifugal and shrouded; and   the impellers of the second set being centrifugal and shrouded.   
     
     
         11 . An LNG plant comprising a compression train according to  claim 1 . 
     
     
         12 . The LNG plant of  claim 10 , further comprising two compression trains. 
     
     
         13 . The LNG plant of  claim 11 , wherein the or each first centrifugal compressor is arranged to compress a high molecular weight gas,
 wherein the or each second centrifugal compressor is arranged to compress a low molecular weight gas; the or each first centrifugal compressor and the or each second centrifugal compressor cooperating to liquefy a flow of natural gas.   
     
     
         14 . The compression train of  claim 1 , wherein the high molecular weight gas is higher than 40. 
     
     
         15 . The compression train of  claim 1 , wherein the low molecular weight gas is between 20 and 30. 
     
     
         16 . The compression train of  claim 1 , wherein the compression ratio is higher than 15:1. 
     
     
         17 . The compression train of  claim 2 , wherein the mixed-refrigerant gas is a mixture of propane, ethylene or ethane, and methane. 
     
     
         18 . The compression train of  claim 3 , wherein the engine is an aeroderivative gas turbine