Combined Heat and Power Technology for Natural Gas Liquefaction Plants

Abstract

Systems and methods for the generation of liquid natural gas (“LNG”) are provided.

We claim: 
     
         1 . A system for the generation of liquefied natural gas comprising:
 a) a first gas turbine;   b) a first steam generator in gaseous communication with the first gas turbine;   c) a second gas turbine;   d) a second steam generator in gaseous communication with the second gas turbine;   e) a steam turbine in gaseous communication with the first steam generator and the second steam generator; and   f) an electrical generator in mechanical communication with the steam turbine.   
     
     
         2 . The system of  claim 1 , further comprising a first helper motor and a second helper motor electrically connected to the generator. 
     
     
         3 . The system of  claim 2 , wherein the first helper motor is mechanically connected to the first gas turbine and the second helper motor is mechanically connected to the second gas turbine. 
     
     
         4 . The system of  claim 2 , wherein the first helper motor and the second helper motor are synchronous or induction motors. 
     
     
         5 . The system of  claim 4 , wherein the synchronous or induction motors are connected to voltage source inverter drives. 
     
     
         6 . The system of  claim 1 , further comprising a first shaft attached to the first gas turbine and a second shaft attached to the second gas turbine. 
     
     
         7 . The system of  claim 6 , further comprising at least a first refrigeration compressor attached to the first shaft and at least a second refrigeration compressor attached to the second shaft. 
     
     
         8 . The system of  claim 7 , further comprising at least a first cooler in liquid communication with the at least a first refrigeration compressor and at least a second cooler in liquid communication with the at least a second refrigeration compressor. 
     
     
         9 . The system of  claim 8 , further comprising a scrub column in gaseous communication with the plurality of coolers. 
     
     
         10 . The system of  claim 9 , further comprising a cryogenic heat exchanger in gaseous communication with the scrub column. 
     
     
         11 . The system of  claim 10 , further comprising a liquefied natural gas storage tank in liquid communication with the cryogenic heat exchanger. 
     
     
         12 . The system of  claim 11 , further comprising a boil off gas compressor in gaseous communication with the liquefied natural gas storage tank. 
     
     
         13 . The system of  claim 12 , further comprising a boil off gas compressor motor connected to the boil off gas compressor and electrically connected to the generator. 
     
     
         14 . The system of  claim 13 , wherein the boil off gas compressor motor is a high speed synchronous or induction motor. 
     
     
         15 . The system of  claim 14 , wherein the high speed motor is connected to a variable frequency drive. 
     
     
         16 . A waste heat recovery system, comprising:
 a) a first gas turbine;   b) a first steam generator in gaseous communication with the first gas turbine;   c) a second gas turbine;   d) a second steam generator in gaseous communication with the second gas turbine;   e) a steam turbine in gaseous communication with the first steam generator and the second steam generator; and   f) an electrical generator in mechanical communication with the steam turbine.   
     
     
         17 . A method for the reduction of fuel gas consumption during the production of liquefied natural gas in a liquefied natural gas facility comprising a first gas turbine that generates a first amount of waste heat upon operation and a second gas turbine that generates a second amount of waste heat upon operation, comprising:
 a) utilizing the first amount of waste heat from the first gas turbine in a first heat recovery steam generator to produce a first amount of steam;   b) utilizing the second amount of waste heat from the second gas turbine in a second heat recovery steam generator to produce a second amount of steam;   c) utilizing at least a portion of the first amount of steam and the second amount of steam in a steam turbine;   d) producing electricity from a generator connected to the steam turbine; and   e) utilizing the electricity to power at least a first process that consumes electrical power generated from fuel gas used during the production of liquefied natural gas in a liquefied natural gas facility, thereby reducing fuel gas consumption.   
     
     
         18 . The method of  claim 17 , wherein the at least a first process that consumes electrical power generated from fuel gas is operation of a first helper motor. 
     
     
         19 . The method of  claim 17 , wherein the at least a first process that consumes electrical power generated from fuel gas is operation of a boil off gas compressor motor. 
     
     
         20 . The method of  claim 17 , wherein the at least a first process that consumes fuel gas is production of electricity used in the liquefied natural gas facility. 
     
     
         21 . The method of  claim 17 , comprising utilizing the electricity to power at least a first and at least a second process that consume fuel gas used during the production of liquefied natural gas in a liquefied natural gas facility. 
     
     
         22 . The method of  claim 21 , wherein the at least a first process that consumes fuel gas is operation of a first helper motor and the at least a second process that consumes fuel gas is operation of a second helper motor. 
     
     
         23 . A method for the reduction of greenhouse gas emissions during the production of liquefied natural gas in a liquefied natural gas facility comprising a first gas turbine that generates a first amount of waste heat upon operation and a second gas turbine that generates a second amount of waste heat upon operation, comprising:
 a) utilizing the first amount of waste heat from the first gas turbine in a first heat recovery steam generator to produce a first amount of steam;   b) utilizing the second amount of waste heat from the second gas turbine in a second heat recovery steam generator to produce a second amount of steam;   c) utilizing at least a portion of the first amount of steam and the second amount of steam in a steam turbine;   d) producing electricity from a generator connected to the steam turbine; and   e) utilizing the electricity to power at least a first process that generates greenhouse gas emissions used during the production of liquefied natural gas in a liquefied natural gas facility, thereby reducing greenhouse gas emissions.   
     
     
         24 . A plant for the generation of liquefied natural gas comprising:
 a) an inlet gas reception unit connected to a natural gas pipeline;   b) a gas treating and dehydration unit in gaseous communication with the inlet gas reception unit;   c) a liquefaction unit in gaseous communication with the gas treating and dehydration unit;   d) a storage and loading unit in liquid communication with the liquefaction unit; and   e) a waste heat recovery system in communication with the liquefaction unit, comprising:
 i) a first steam generator; 
 ii) a second steam generator; 
 iii) a steam turbine in gaseous communication with the first steam generator and the second steam generator; and 
 iv) an electrical generator connected to the steam turbine. 
   
     
     
         25 . A plant for the generation of liquefied natural gas comprising:
 a) a pig receiver connected to a natural gas pipeline;   b) a filter coalescer in gaseous communication with the pig receiver;   c) a meter in gaseous communication with the filter coalescer;   d) an acid gas absorber in gaseous communication with the meter;   e) a drier precooler in gaseous communication with the acid gas absorber;   f) a drier inlet separator in gaseous communication with the drier precooler;   g) a plurality of gas driers in gaseous communication with the drier inlet separator;   h) a first gas turbine in gaseous communication with the plurality of gas driers;   i) a first plurality of refrigeration compressors connected to the first gas turbine;   j) a second gas turbine in gaseous communication with the plurality of gas driers;   k) a second plurality of refrigeration compressors connected to the second gas turbine;   l) a mercury adsorber in gaseous communication with the plurality of gas driers;   m) a filter in gaseous communication with the mercury adsorber;   n) a plurality of coolers in gaseous communication with the filter;   o) a scrub column in gaseous communication with the plurality of coolers;   p) a cryogenic heat exchanger in gaseous communication with the scrub column;   q) a LNG storage tank in fluid communication with the cryogenic heat exchanger;   r) a boil off gas compressor in gaseous communication with the LNG storage tank;   s) a high speed motor connected to the boil off gas compressor;   t) a variable frequency drive connected to the high speed motor; and   u) a waste heat recovery system, comprising:
 i) a first steam generator in gaseous communication with the first gas turbine; 
 ii) a second steam generator in gaseous communication with the second gas turbine; 
 iii) a steam turbine in gaseous communication with the first steam generator and the second steam generator; and 
 iv) an electrical generator connected to the steam turbine.