Eastman AdapT for ammonia production
In natural gas-based ammonia production, steam reforming and partial oxidation technology are used to convert natural gas into syngas that consists mainly of hydrogen and nitrogen. The carbon present in the natural gas feedstock is mainly converted to carbon monoxide (CO) and carbon dioxide (CO2). The syngas is then processed in a shift reactor to convert CO into CO2, which generates additional hydrogen. Complete removal of CO and CO2 is required because they both are poisons for the ammonia synthesis catalyst.
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The removal of CO2 downstream of the shift reactor typically involves an amine-based acid gas removal process. The final purification step is a catalytic methanation bed to convert any residual CO or CO2 into methane, an inert gas in the ammonia synthesis loop.
Challenges
Selecting the optimal solvent and plant design for CO2 removal involves balancing the removal rate, energy use and cost. Typically, the gas to the methanator contains 500 to 1,000 parts per million by volume of residual CO2. Due to plant optimization and energy integration, a limited amount of heat is available in the complex to drive amine regeneration. In addition to the correct selection of amine solvent, the plant design is geared toward minimizing energy consumption by applying flash regeneration to the bulk of the amine solvent.
The CO2 stream is either vented or reused for urea production, where ammonia is a precursor. Maximizing CO2 stream pressure is crucial for urea production, influencing plant design and solvent selection.
Eastman’s answer
Eastman AdapT flexible gas sweetening solutions are formulated to achieve targeted CO2 removal while minimizing energy consumption. Eastman’s technical services team can help in optimizing plant design.