Polygeneration production of power and fertilizer through emissions capture

Abstract

Method for the production of ammonia, and optionally urea, from a flue gas effluent from an oxy-fired process, wherein the production of ammonia and optionally urea includes a net power production. Also provided is a method to effect cooling in an oxy-fired process with air separation unit exit gases utilizing either closed or open cooling loop cycles.

1 . A method for the production of ammonia from exhaust flue gases of an oxygen-fired process, the method comprising the steps of:
 supplying a hydrocarbon or carbonaceous feedstock and oxygen to an oxygen-fired process to produce an exhaust flue gas, said exhaust flue gas comprising carbon dioxide, carbon monoxide, and hydrogen;   supplying the exhaust flue gas to a first reactor, said first reactor comprising a catalyst and being configured to convert at least a portion of the carbon monoxide to carbon dioxide and produce a modified exhaust flue gas;   supplying the modified exhaust flue gas to a second reactor, said second reactor comprising a catalyst and being configured to convert any remaining carbon monoxide to carbon dioxide to produce a carbon dioxide-rich exhaust flue gas;   supplying the carbon dioxide-rich exhaust flue gas from the second reactor to a first condenser to remove water and produce a gas stream comprising primarily hydrogen and carbon dioxide;   supplying the gas stream comprising primarily hydrogen and carbon dioxide from the first condenser to a carbon dioxide stripper to produce a hydrogen stream and a high purity carbon dioxide stream, said carbon dioxide stripper being charged with a solvent suitable for extracting a carbon dioxide, and wherein the hydrogen stream comprises minor amounts of carbon monoxide and carbon dioxide;   supplying the hydrogen stream to a third reactor, said third reactor comprising a catalyst and being configured for the production methane from the minor amounts of carbon monoxide and carbon dioxide present in the hydrogen stream, said third reactor producing a methane product stream and a high purity hydrogen stream;   supplying the high purity hydrogen stream from the third reactor and nitrogen gas from an air separation unit to a fourth reactor, said fourth reactor comprising a catalyst and being configured to produce an ammonia product stream;   supplying the high purity carbon dioxide stream from the carbon dioxide stripper and the ammonia from the fourth reactor to a fifth reactor, said fifth reactor being configured to produce a product stream comprising urea.   
     
     
         2 . The method of  claim 1 , wherein the hydrocarbon feedstock is selected from methane or syngas. 
     
     
         3 . The method of  claim 1 , wherein the hydrocarbon feedstock is a hydrocarbon fuel source that, when combusted to form the exhaust flue gas, can be subjected to decontamination. 
     
     
         4 . The method of  claim 1 , further comprising utilizing a hydrogen generator, wherein the hydrogen generator produces hydrogen and oxygen from a water feedstock, wherein the hydrogen is supplied to the fourth reactor and the oxygen is supplied to the oxygen-fired process. 
     
     
         5 . The method of  claim 1 , wherein the oxygen has a purity of at least 99%. 
     
     
         6 . The method of  claim 1 , wherein the composition of the gas stream comprising primarily hydrogen and carbon dioxide comprises between 65-80% hydrogen, between 20-35% carbon dioxide and between 0-8% carbon monoxide. 
     
     
         7 . The method of  claim 5 , further comprising separating nitrogen and oxygen from air with an air separation unit, and wherein the nitrogen is supplied to the fourth reactor and oxygen is supplied to the oxygen-fired process. 
     
     
         8 . The method of  claim 1 , further comprising supplying hydrogen from a hydrogen generator to the oxygen-fired process with the hydrocarbon feedstock and oxygen to produce the exhaust flue gas. 
     
     
         9 . The method of  claim 1 , further comprising the step of supplying the high purity hydrogen stream from the third reactor to a second condenser, said second condenser being configured to remove any trace water present in the high purity hydrogen stream. 
     
     
         10 . The method of  claim 8 , further comprising the step of supplying water recovered from the first and second condensers to the hydrogen generator as feedstock. 
     
     
         11 . The method of  claim 1 , further comprising using gases exiting the air separation unit as media for heat exchangers for gases exiting the oxygen-fired process or associated processes and auxiliary load heat sinks.