(US5733941-A)      The conversion of a lighter hydrocarbon gas to heavier hydrocarbons involves: (a) reacting an air feed and lighter hydrocarbon gas feed to produce a synthesis gas comprising hydrogen and carbon monoxide, (b) reacting the synthesis gas in the presence of a hydrocarbon synthesis catalyst to produce heavier hydrocarbons, a tail gas and water, (c) combusting the tail gas to produce a combustion gas, (d) generating mechanical power with the combustion gas and (e) compressing the air feed with the mechanical power.    An apparatus for converting a lighter hydrocarbon gas to heavier hydrocarbons comprises: (a) a gas reformer reactor with a feed gas inlet for receiving a gaseous mixture of air feed, lighter hydrocarbon feed gas and process gas, and a synthesis gas outlet for discharging the synthesis gas, (b) a hydrocarbon synthesis reactor containing a hydrocarbon synthesis catalyst with an inlet for receiving the gas and a product stream outlet for discharging a product stream, (c) a combustor with a tail gas inlet and a combustion gas outlet, (d) a power turbine having combustion gas inlet to drive the power turbine, the turbine engaging a drive shaft and (e) an air compressor engaging the drive shaft for driving the air compressor and compressing the air feed.    USE -   For conversion of lighter hydrocarbon gas to heavier hydrocarbons useful as fuels.    ADVANTAGE -   Effective process for conversion which has reduced power requirements and reduced capital equipment costs. Produces reduced levels of contaminants to the environment.    (EP912472-A1)      The conversion of a lighter hydrocarbon gas to heavier hydrocarbons involves: (a) reacting an air feed and lighter hydrocarbon gas feed to produce a synthesis gas comprising hydrogen and carbon monoxide, (b) reacting the synthesis gas in the presence of a hydrocarbon synthesis catalyst to produce heavier hydrocarbons, a tail gas and water, (c) combusting the tail gas to produce a combustion gas, (d) generating mechanical power with the combustion gas and (e) compressing the air feed with the mechanical power.    An apparatus for converting a lighter hydrocarbon gas to heavier hydrocarbons comprises: (a) a gas reformer reactor with a feed gas inlet for receiving a gaseous mixture of air feed, lighter hydrocarbon feed gas and process gas, and a synthesis gas outlet for discharging the synthesis gas, (b) a hydrocarbon synthesis reactor containing a hydrocarbon synthesis catalyst with an inlet for receiving the gas and a product stream outlet for discharging a product stream, (c) a combustor with a tail gas inlet and a combustion gas outlet, (d) a power turbine having combustion gas inlet to drive the power turbine, the turbine engaging a drive shaft and (e) an air compressor engaging the drive shaft for driving the air compressor and compressing the air feed.    USE -   For conversion of lighter hydrocarbon gas to heavier hydrocarbons useful as fuels.    ADVANTAGE -   Effective process for conversion which has reduced power requirements and reduced capital equipment costs. Produces reduced levels of contaminants to the environment.