Systems and processes for processing hydrogen and carbon monoxide

Abstract

In various implementations, various feed gas streams which include hydrogen and carbon monoxide may be processed for conversion to product streams. For example, the feed gas stream may be processed using the Fischer-Tropsch process. Unconverted hydrogen and carbon monoxide can be recycled using an off-gas catalytic reformer and a gas turbine exhaust gas heat exchanger that will perform preheating duties.

What is claimed is: 
     
         1 . A process for producing higher molecular weight hydrocarbon compounds and/or oxygenates from a hydrocarbon gas comprising methane, said process comprising:
 generating an initial synthesis gas (“syngas”) stream comprising carbon monoxide and hydrogen in a two-stage process by reaction of hydrocarbon gas comprising methane, steam and oxygen;   generating oxygen in an air separation plant having an air compressor driven by a gas turbine.   combusting a fuel gas in exhaust from the gas turbine in a fired heater to provide at least a portion of a heat duty for preheating feed streams to synthesis gas production units;   catalytically converting synthesis gas to at least one of hydrocarbons or oxygenates in a process unit, at least a portion of the initial syngas stream is provided as feed gas to the process unit;   separating off-gas from the syngas conversion process, the off-gas including unreacted syngas from the syngas feed stream, inerts, reaction products, CO 2  and water vapour;   generating additional synthesis gas in a catalytic steam/hydrocarbon reformer using the off-gas, a first part of the off-gas is used to provide at least a portion of the fuel gas for the reformer heating, and a second portion is used to provide at least a portion of the feed to the catalytic reformer mixed with steam;   combining the additional syngas with the initial syngas to form a feed for the syngas catalytic conversion process;   adding the combustion gas exiting the off-gas catalytic reformer furnace to the hot combustion gas used for process heating in the gas turbine exhaust fired heater; and   adding the reformed synthesis gas stream leaving the off-gas catalytic reformer furnace to the initial syngas stream up-stream of a waste heat boiler producing high pressure steam for sythesis gas generation.   
     
     
         2 . The method of  claim 1  further comprising using at least a portion of the hot exhaust from the gas turbine compressed as combustion air for the off-gas catalytic reformer furnace burners 
     
     
         3 . The method of  claim 1  further comprising using at least a portion of air taken from the air separation unit air compressor at a suitable interstage point before the intercooler having the required pressure for the burners as combustion air for the off-gas catalytic reformer furnace. 
     
     
         4 . The method of  claim 1 , wherein generating the initial syngas stream comprises:
 reacting hydrocarbon-containing fuel with an oxidant gas comprising molecular oxygen and steam in a first autothermal catalytic reformer to produce a syngas product; and   endothermically reforming hydrocarbon-containing fuel gas with steam over a catalyst in a heat exchange reformer to produce a heat exchange-reformed syngas product, wherein at least a portion of the heat used in the generation of said heat exchange-reformed syngas product is obtained by recovering heat from the syngas product leaving the autothermal catalytic reformer.   
     
     
         5 . The method of  claim 1 , wherein generating the initial syngas stream comprises:
 exothermically reacting hydrocarbon-containing fuel with an oxidant gas comprising molecular oxygen in a first reactor to produce an exothermically-generated syngas product; and   endothermically reforming hydrocarbon-containing fuel gas with steam over a catalyst in a heat exchange reformer to produce a heat exchange-reformed syngas product, wherein at least a portion of the heat used in the generation of said heat exchange-reformed syngas product is obtained by recovering heat from the exothermically-generated syngas product.   
     
     
         6 . The method of  claim 1 , the syngas conversion process comprises a Fischer-Tropsch system. 
     
     
         7 . The method of  claim 1 , the syngas conversion process comprises a methanol system. 
     
     
         8 . The method of  claim 1 , further comprising separating CO 2  from the feed gas stream entering the syngas conversion process and recycling at least a portion of the compressed CO 2  to the initial syngas generation system to form an initial syngas having a CO to H 2  ratio higher than that required by the catalytic syngas conversion process and simultaneously operating the off-gas reformer to produce a syngas product having a low CO to H 2  ratio such that the mixed streams have the required CO to H 2  ratio for the catalytic syngas conversion process and the quantity of CO 2  recycled is maximized. 
     
     
         9 . The method of  claims 1 , further comprising adding additional fresh hydrocarbon feed to the off-gas catalytic reformer to allow additional H 2  production to ensure all the available CO 2  separated from the feed syngas to the syngas catalytic conversion process is recycled to the initial syngas production system. 
     
     
         10 . A system for producing higher molecular weight hydrocarbon compounds and/or oxygenates from a hydrocarbon gas comprising methane, said system comprising:
 synthesis gas production units that generate an initial synthesis gas (“syngas”) stream in a two stage process comprising carbon monoxide and hydrogen by reaction of hydrocarbon gas comprising methane with steam and oxygen;   an air separation plant that generates oxygen having an air compressor driven by a gas turbine;   a fired heater that combusts exhaust from the gas turbine to provide at least a portion of the heat duty for preheating feed streams to the synthesis gas production units;   a process unit that catalytically converts synthesis gas to at least one of hydrocarbons or oxygenates and separates off-gas from synthesis gas, at least a portion of the initial syngas stream is provided as feed gas, the off-gas including unreacted syngas from the syngas feed stream, inerts, reaction products, CO 2  and water vapour;   an off-gas catalytic steam/hydrocarbon reformer that generates additional synthesis gas using the off-gas, a first part of the off-gas is used to provide at least a portion of the fuel gas for the reformer heating, and a second portion is used to provide at least a portion of the feed to the catalytic reformer mixed with steam;   a first outlet that combines the additional syngas with the initial syngas to form a feed for the syngas catalytic conversion process;   a second outlet that adds the combustion gas exiting the off-gas catalytic reformer furnace to the hot combustion gas used for process heating in the gas turbine exhaust fired heater; and   a third outlet that adds the reformed synthesis gas stream leaving the off-gas catalytic reformer furnace to the initial syngas stream up-stream of a waste heat boiler producing high pressure steam for sythesis gas generation.   
     
     
         11 . The system of  claim 10  further comprising using at least a portion of the hot exhaust from the gas turbine compressed as combustion air for the off-gas catalytic reformer furnace burners. 
     
     
         12 . The system of  claim 10  further comprising using at least a portion of air taken from the air separation unit air compressor at a suitable interstage point before the intercooler having the required pressure for the burners as combustion air for the off-gas catalytic reformer furnace. 
     
     
         13 . The system of  claim 10 , wherein the synthesis gas production units comprise:
 autothermal reforming reactor that exothermically reacts hydrocarbon-containing fuel with an oxidant gas comprising molecular oxygen in a first reactor to produce an exothermically-generated syngas product; and   a gas-heated reformer that endothermically reforms hydrocarbon-containing fuel gas with steam over a catalyst in a heat exchange reformer to produce a heat exchange-reformed syngas product, wherein at least a portion of the heat used in the generation of said heat exchange-reformed syngas product is obtained by recovering heat from the exothermically-generated syngas product.   
     
     
         14 . The system of  claim 10 , wherein generating the initial syngas stream comprises:
 partial oxidation reactor that exothermically reacts hydrocarbon-containing fuel with an oxidant gas comprising molecular oxygen in a first reactor to produce an exothermically-generated syngas product; and   a gas heated reformer that endothermically reforms hydrocarbon-containing fuel gas with steam over a catalyst in a heat exchange reformer to produce a heat exchange-reformed syngas product, wherein at least a portion of the heat used in the generation of said heat exchange-reformed syngas product is obtained by recovering heat from the exothermically-generated syngas product.   
     
     
         15 . The system of  claim 10 , the syngas conversion process unit comprises a Fischer-Tropsch system. 
     
     
         16 . The system of  claims 10 , the syngas conversion process comprises a methanol system. 
     
     
         17 . The system of  claims 10 , further comprising a filter that separates CO 2  from the feed gas stream entering the syngas conversion process and recycling at least a portion of the compressed CO 2  to the initial syngas generation system to form an initial syngas having a CO to H 2  ratio higher than that required by the catalytic syngas conversion process and simultaneously operating the off-gas reformer to produce a syngas product having a low CO to H 2  ratio such that the mixed streams have the required CO to H 2  ratio for the catalytic syngas conversion process and the quantity of CO 2  recycled is maximized. 
     
     
         18 . The system of  claims 10 , further comprising a hydrocarbon inlet that adds additional fresh hydrocarbon feed to the off-gas catalytic reformer to allow additional H 2  production to ensure all the available CO 2  separated from the feed syngas to the syngas catalytic conversion process is recycled to the initial syngas production system.