Flexible installation of a hydrocarbon liquefaction unit

Abstract

Natural gas liquefaction unit including at least one cryogenic cold box having at least one heat exchanger; a fixed assembly zone on its outer wall; at least one closed loop nitrogen refrigeration cycle; at least one device for equipment required for implementing the liquefaction of a natural gas stream from a hydrocarbon supply stream; at least one interconnection module comprising a pipe holder means and a set of pipes and valves, designed to connect said at least one cold box to at least one equipment device for the cycle for refrigerating and/or separating C6+ type hydrocarbon elements contained in the natural gas, wherein the interconnection module rests on a frame allowing it to be handled and is connected to the cold box and to the other method or equipment sub-assemblies located around said fixed assembly zone.

1 . Natural gas liquefaction unit comprising:
 at least one cryogenic cold box ( 2 ) comprising:   at least one heat exchanger;   a fixed assembly zone ( 8 ) on its outer wall;   at least one closed loop nitrogen refrigeration cycle;   at least one device ( 3 ) for equipment required for implementing the liquefaction of a natural gas stream from a hydrocarbon supply stream;   at least one interconnection module ( 4 ) comprising a pipe holder means and a set of pipes and valves ( 5 ,  6 ,  7 ), designed to connect said at least one cold box ( 2 ) to at least one equipment device for the cycle for refrigerating and/or separating C6+ type hydrocarbon elements contained in the natural gas,   
       characterized in that the interconnection module ( 4 ) rests on a frame allowing it to be handled and is connected to the cold box ( 2 ) and to the other method or equipment sub-assemblies ( 3 ) located around said fixed assembly zone ( 8 ). 
     
     
         2 . Unit according to the preceding claim, characterized in that the interconnection module ( 4 ) particularly comprises one or more elements selected from among control valves, manual valves, sample connections, pipes, pre-cut panels with valve actuators, instruments, vapour sources, lighting, ladders and platforms, pre-wired junction boxes, platforms for instrument/electric cables, pipe supports, channeling. 
     
     
         3 . Unit according to  claim 2 , characterized in that the interconnection module ( 4 ) comprises one or more elements selected from among control valves, manual valves, valve actuators. 
     
     
         4 . Unit according to one of the preceding claims, characterized in that said other method or equipment sub-assemblies ( 3 ) are required to implement at least one method function selected from among the compression of the nitrogen of the refrigeration cycle, the overpressurization of the nitrogen of the refrigeration cycle, the expansion of the nitrogen of the refrigeration cycle, the cooling of the nitrogen of the refrigeration cycle, the liquefaction of the natural gas stream, the separation of the C6+ type hydrocarbons contained in the natural gas, the interconnection module ( 4 ) being devoid of such method or equipment sub-assemblies. 
     
     
         5 . Unit according to one of the preceding claims, characterized in that the refrigeration cycle comprises a first means for compressing the nitrogen of the refrigeration cycle, a means for cooling the nitrogen of the refrigeration cycle, a second means for compressing the nitrogen of the refrigeration cycle, said second compression means comprising two booster compressors coupled to two respective expansion means, said booster compressors being configured to compress the nitrogen of the refrigeration cycle at an identical pressure. 
     
     
         6 . Unit according to one of the preceding claims, characterized in that said frame has a metal structure. 
     
     
         7 . Unit according to one of the preceding claims, characterized in that said at least one heat exchanger is a brazed aluminium heat exchanger. 
     
     
         8 . Use of a unit as defined in one of the preceding claims for liquefying a natural gas stream. 
     
     
         9 . Method for starting a liquefaction unit as defined in  claims 1  to  6 , comprising the following steps:
 on-site installation of a closed loop nitrogen refrigeration cycle and of a cold box ( 2 ) comprising: 
 at least one heat exchanger; 
 a fixed assembly zone ( 8 ) on its outer wall; 
 on-site installation of an interconnection module ( 4 ) comprising a pipe holder means and a set of pipes and valves ( 5 ,  6 ,  7 ), designed to connect said at least one cold box ( 2 ) to at least one equipment device ( 3 ) for the cycle for refrigerating and/or separating C6+ type hydrocarbon elements contained in the natural gas; 
 fixing said interconnection module ( 4 ) to the cold box ( 2 ) and to at least one equipment device ( 3 ), allowing the implementation of the liquefaction method using said cold box ( 2 ), already available on the site.