Apparatus and process to condition natural gas for transportation

Abstract

A conditioning assembly to condition a flow of natural gas to reduce hydrate formation for transportation. The conditioning assembly includes a housing with an inlet for introducing a flow of natural gas and an outlet for delivering conditioned gas, wherein the housing is capable of containing natural gas at or above atmospheric pressure. The assembly also includes at least one tube and fin style heat exchanger contained within the housing configured to cool the flow of natural gas to a temperature below hydrate formation temperature and a collection arrangement to remove hydrates from the housing that form during cooling of the natural gas. Also disclosed is a method of conditioning natural gas, substantially corresponding to the assembly described above, wherein a constant flow of natural gas is conditioned by alternating the flow of natural gas between at least two heat exchangers configured in a parallel arrangement.

1 - 16 . (canceled) 
     
     
         17 . A method of conditioning natural gas to reduce subsequent hydrate formation, the method including the steps of:
 introducing a flow of natural gas to a heat exchanger;   cooling the natural gas to a temperature at or below the hydrate formation temperature; and   removing from the natural gas hydrates that form during the cooling, wherein a constant flow of natural gas is conditioned by alternating the flow of natural gas between at least two heat exchangers configured in a parallel arrangement.   
     
     
         18 . The method as claimed in  claim 17 , wherein hydrate formation is reduced during subsequent cooling of the natural gas. 
     
     
         19 . The method as claimed in  claim 18 , wherein the subsequent cooling occurs during transportation of the natural gas. 
     
     
         20 . The method as claimed in  claim 17 , wherein the flow of natural gas is cooled via indirect heat transfer. 
     
     
         21 . The method as claimed in  claim 17 , wherein the hydrates form on, and are removed from, the surfaces of the heat exchanger. 
     
     
         22 . The method as claimed in  claim 21 , wherein the heat exchanger is a tube and fin style heat exchanger and hydrates form on the fins of the heat exchanger. 
     
     
         23 . The method as claimed in  claim 22 , wherein spacing of the fins at an inlet of the heat exchanger is greater than spacing of the fins at an outlet of the heat exchanger. 
     
     
         24 . The method as claimed in  claim 20 , wherein water included in the natural gas condenses during cooling. 
     
     
         25 . The method as claimed in  claim 24 , wherein the cooling occurs in at least two stages:
 a first stage wherein the natural gas is cooled to a temperature where water condenses and is collected; and   a second stage wherein the natural gas is cooled to a temperature below hydrate formation temperature such that hydrates form and are collected.   
     
     
         26 . The method as claimed in  claim 25 , wherein the natural gas is cooled in the first stage to a temperature about 3 to 5K above the hydrate formation temperature, wherein the hydrate formation temperature is typically between 0° C. and 8° C. 
     
     
         27 . The method as claimed in  claim 17 , wherein the flow of natural gas is ceased in order for the hydrates to be collected. 
     
     
         28 . The method as claimed in  claim 27 , wherein the hydrates are collected by warming the heat exchanger such that hydrates melt and the resulting liquid is collected. 
     
     
         29 . A conditioning assembly to condition a flow of natural gas to reduce hydrate formation for transportation, the conditioning assembly including:
 a housing including an inlet for introducing a flow of natural gas and an outlet for delivering conditioned gas capable of containing natural gas at or above atmospheric pressure;   a first and a second heat exchanger contained within the housing in a parallel arrangement, each configured to cool the flow of natural gas to a temperature below hydrate formation temperature; and   a collection arrangement to remove hydrates from the housing that form during cooling of the natural gas,   wherein a constant flow of natural gas is conditioned by alternating the flow of natural gas between the heat exchangers.   
     
     
         30 . The conditioning assembly as claimed in  claim 29 , wherein the heat exchangers are tube and fin style heat exchangers, wherein the hydrates form on the surfaces of the fins and on the outside of the tubes. 
     
     
         31 . The conditioning assembly as claimed in  claim 30 , wherein spacing of the fins varies according to expected hydrate formation location. 
     
     
         32 . The conditioning assembly as claimed in  claim 29 , wherein spacing of the fins at an inlet of the heat exchanger is greater than spacing of the fins at an outlet of the heat exchanger. 
     
     
         33 . The conditioning assembly as claimed in  claim 29 , wherein the conditioning assembly includes at least two zones:
 a first zone wherein the natural gas is cooled to a temperature where water condenses and is collected; and   a second zone wherein the natural gas is cooled to a temperature below hydrate formation such that hydrates form and are collected.   
     
     
         34 . The conditioning assembly as claimed in  claim 33 , wherein the natural gas is cooled in the first zone to a temperature about 3 to 5K above the hydrate formation temperature, wherein the hydrate formation temperature is typically between 0° C. and 8° C. 
     
     
         35 . The conditioning assembly as claimed in  claim 29 , wherein hydrates are removed by ceasing the flow of the natural gas, warming the heat exchanger and collecting the resulting liquid.