ELECTROCHEMICAL CO2 SEPARATION FOR AMMONIA PLANTS

AMMONIA SYNTHESIS IS ONE OF THE LARGEST AND MOST ENERGY INTENSIVE MANUFACTURING PROCESSES. FOR A TYPICAL SINGLE TRAIN AMMONIA SYNTHESIS PLANT, THE ENERGY REQUIREMENTS FOR AMMONIA PRODUCTION ARE 29 GJ/TON NH3. ONE OF THE MORE ENERGY INTENSIVE STEPS INVOLVED IN PURIFYING THE SYNGAS STREAM IS REMOVAL OF CO2 FROM THE STEAM REFORMED METHANE GAS STREAM. THE CURRENT CO2 REMOVAL TECHNOLOGIES CONSUME APPROXIMATELY 10 PERCENT OF THE ENERGY REQUIRED TO PREPARE NH3. SIGNIFICANT IMPROVEMENTS TO THESE RELATIVELY MATURE TECHNOLOGIES ARE NOT EXPECTED AND, THEREFORE, THERE ARE INCENTIVES TO DEVELOP NEW CO2 PROCESSES THAT CAN BE STAGED WITH THE CURRENT CO2 PROCESSES TO SIGNIFICANTLY REDUCE ENERGY INPUTS. PRELIMINARY ECONOMIC ANALYSES OF ALTERNATIVE TECHNOLOGIES SHOW THAT BY USING ELECTROCHEMICAL CO2 REMOVAL TO REMOVE THE LAST TRACES OF CO2 AND USING A CONVENTIONAL AMINE BASED SYSTEM TO REMOVE THE BULK OF THE CO2, THE ENERGY REQUIREMENTS FOR CO2 REMOVAL CAN BE REDUCED BY A FACTOR OF TWO. RESEARCHERS PROPOSE TO DEMONSTRATE THE FEASIBILITY OF THE ELECTROCHEMICAL CO2 CONCENTRATION CYCLE.