System and apparatus for liquefaction of natural gas

Abstract

Described herein are apparatuses and systems related to at-shore liquefaction of natural gas. The systems can include land-based facilities connected to a source of electricity and feed gas, an at-shore water-based apparatus comprising a hull, an air-cooled electrically-driven refrigeration system (“AER System”), and a plurality of liquefied natural gas (“LNG”) storage tanks that are on a lower deck of the hull. The AER System can comprise one or more refrigeration trains, where each refrigeration train of the one or more refrigeration trains can include a portion of electrically-driven compressors and a portion of air coolers that at least or only partially cover the one or more refrigeration trains.

What is claimed is: 
     
         1 . A system for liquefaction of natural gas, the system comprising:
 land-based facilities connected to a source of electricity and feed gas; and   an at-shore water-based apparatus separate from but connected to the land-based facilities, wherein the source of electricity and feed gas is external to the at-shore water-based apparatus and the water-based apparatus is moored to an at-shore location, the water-based apparatus comprising:
 a hull configured to be operable when moored to the at-shore location, the hull defining a bow, a stern, and a centerline axis extending from the bow to the stern; 
 an air-cooled electrically-driven refrigeration system (“AER System”) comprising one or more interconnected modules operatively configured to (i) receive electricity and feed gas from the source of electricity and feed gas, (ii) perform a refrigeration process for converting the feed gas into a liquefied natural gas (“LNG”) with the received electricity using a plurality of electrically-driven compressors and a cryogenic heat exchanger operatively configured on the water-based apparatus, (iii) discharge substantially all thermal energy from the refrigeration process to ambient air with air coolers operatively configured on the water-based apparatus, and (iv) output the LNG; and 
 a plurality of LNG storage tanks that are on a lower deck of the hull, the plurality of LNG storage tanks operatively configured to receive the LNG from the AER System, and operatively configured to output the LNG to an LNG transport vessel that is separate from the water-based apparatus; wherein: 
 the AER System comprises one or more refrigeration trains; 
 each refrigeration train of the one or more refrigeration trains comprises a portion of the electrically-driven compressors and a portion of the air coolers; and 
 the air coolers at least or only partially cover the one or more refrigeration trains. 
   
     
     
         2 . The system of  claim 1 , wherein the plurality of LNG storage tanks is spaced apart in a single row along the centerline axis of the hull such that the storage volume of each tank is approximately centered on the centerline axis. 
     
     
         3 . The system of  claim 1 , wherein the source of feed gas generates the feed gas by removing unwanted elements. 
     
     
         4 . The system of  claim 3 , wherein the unwanted elements include at least heavy hydrocarbons. 
     
     
         5 . The system of  claim 1 , wherein the feed gas is at least partially pre-processed. 
     
     
         6 . The system of  claim 1 , wherein the AER System outputs a fuel gas to the source of electricity and feed gas. 
     
     
         7 . The system of  claim 1 , wherein the source of electricity generates a portion of the electricity received by the AER System and the at-shore location comprises a jetty, a quayside, a shoreline or a position proximate to a shoreline location. 
     
     
         8 . The system of  claim 7 , wherein the source of electricity comprises a gas-powered generator operative to generate the portion of the electricity received by the AER System. 
     
     
         9 . The system of  claim 1 , wherein the one or more interconnected modules utilize dual-mixed refrigerants. 
     
     
         10 . The system of  claim 1 , wherein the source of electricity and feed gas comprise a first source for the electricity and a second source for the feed gas, such that the first source is separate from the second source. 
     
     
         11 . The system of  claim 1 , wherein the means for connecting the water-based apparatus to the land-based facilities comprises a transit bridge extendable between the land-based facilities and the water-based apparatus. 
     
     
         12 . The system of  claim 1 , further comprising:
 a first line for transmitting the electricity from the land-based facilities to the water-based apparatus; and   a second line for carrying the feed gas from the land-based facilities to the water-based apparatus.   
     
     
         13 . The system of  claim 12 , wherein the first line comprises one or more conductors transmitting the electricity. 
     
     
         14 . The system of  claim 13 , wherein:
 the means for connecting the water-based apparatus to the land-based facilities comprises a transit bridge extendable between the land-based facilities and the water-based apparatus; and   the transit bridge supports at least one of the first line and the second line.   
     
     
         15 . The system of  claim 14 , wherein:
 the transit bridge is attached to an at-shore anchor;   the transit bridge comprises a walkway structure; and   the at least one of the first line and the second line that the transit bridge supports is positioned under or adjacent to the walkway structure.   
     
     
         16 . The system of  claim 1 , wherein the water-based apparatus comprises a containment system operatively configured to direct spills of cryogenic fluid over the other one of a port side or a starboard side of the water-based apparatus. 
     
     
         17 . The system of  claim 1 , wherein the system processes and converts the feed gas into LNG without discharging substantial amounts of contaminants to the environment. 
     
     
         18 . The system of  claim 1 , wherein the water-based apparatus comprises a closed loop ballast system operable with a ballast fluid to assist in stabilizing the water-based apparatus moored in proximity to the at-shore location without discharging the ballast fluid to water proximate the at-shore location. 
     
     
         19 . The system of  claim 1 , further comprising:
 a controller operable with the land-based facilities and the at-shore water-based apparatus; and     4  a plurality of sensors comprising sensors of the land-based facilities and sensors of the at-shore water-based apparatus.   
     
     
         20 . The system of  claim 19 , wherein the controller operates the AER System and at least a power supply component at the land-based facilities based on data output from the sensors of the at-shore water-based apparatus and the sensors of the land-based facilities. 
     
     
         21 . The system of  claim 1 , wherein each tank of the plurality of LNG storage tanks is a membrane tank. 
     
     
         22 . The system of  claim 1 , wherein top surfaces the plurality of LNG storage tanks LNG storage tank are spaced apart from an upper deck of the hull to define a void space and the void space is sized and shaped to be capable of containing an amount of fluid having a weight that is approximately equal to a weight of the AER System. 
     
     
         23 . An at-shore water-based apparatus for the liquefaction of natural gas, the apparatus configured to be moored to an at-shore location and connected to a land-based source of electricity and feed gas that is external to the at-shore water-based apparatus, the apparatus comprising:
 a hull configured to be operable when moored to the at-shore location, the hull defining a bow, a stern, and a centerline axis extending from the bow to the stern;   an air-cooled electrically-driven refrigeration system (“AER System”) comprising one or more interconnected modules operatively configured to (i) receive electricity and feed gas from an external source, the external source being separate from the at-shore water-based apparatus, (ii) perform a refrigeration process for converting the feed gas into a liquefied natural gas (“LNG”) with the received electricity using a plurality of electrically-driven compressors and a cryogenic heat exchanger operatively configured on the water-based apparatus, (iii) discharge substantially all thermal energy from the refrigeration process to ambient air with air coolers operatively configured on the water-based apparatus, and (iv) output the LNG; and   a plurality of LNG storage tanks that are on a lower deck of the hull, the plurality of LNG storage tanks operatively configured to receive the LNG from the AER System, and operatively configured to output the LNG to an LNG transport vessel that is separate from the water-based apparatus;   wherein:
 the AER System comprises one or more refrigeration trains; 
 each refrigeration train of the one or more refrigeration trains comprises a portion of the electrically-driven compressors and a portion of the air coolers; and 
 the air coolers at least or only partially cover the one or more refrigeration trains.