Processes for the Production of Ammonia Synthesis Gas

A very important modification of the Poly-bed and Gemini process cycles described above can be used to directly produce an ammonia synthesis gas (a N2 and H2 mixture in the molar ratio of -1 3) from SMROG as feed to the PSA systems. 

For the case of the Poly-bed cycle, it is achieved by using N2 from an external source to (i) countercurrently purge (step f) and pressurize (step i) the adsorbers. These steps introduce weakly adsorbing N2 into the adsorbers before the adsorption step (a) begins. The N2 is expelled out from the adsorber in conjunction with H2 from the feed gas as the effluent stream during step (a) of the Poly-bed system.24 

For the Gemini process, the ammonia synthesis gas can be produced as the effluent gas from step (a) by (i) carrying out the final countercurrent repressurization (step f) of the A beds by introducing N2 from an external source, (ii) eliminating 

The above examples demonstrate the versatility and flexibility of PSA processes designed for the purification of H2 from a bulk feed gas containing 70%-95% H2. All of these processes are designed to meet certain product specifications and to increase the product recoveries at high purities. 

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Having introduced the two main processes for the production of ammonia synthesis gas, the commercial application of the synthesis reaction can now be considered. 

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