AN INDUSTRY CO-PRODUCTION Julie Ashcroft, Johnson Matthey, UK, explores the technologies that have been jointly developed to enable ammonia and methanol co-production as well as retrofits of ammonia plants.
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he production processes for the manufacture of ammonia (NH3) and methanol (CH3OH) are similar in the goal to manufacture syngas as an intermediate prior to the final product, with the processes sharing key upstream unit operations. To develop these synergies, Johnson Matthey (JM) and Kellogg Brown Root (KBR) have formed an alliance to offer co-production standalone flowsheets and retrofits of ammonia plants to incorporate a methanol production section. Both standalone methanol and ammonia plants contain natural gas feedstock purification units and steam methane reformers (SMRs). The gas stream exiting the SMR contains
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syngas, a mixture of hydrogen (H2) and carbon oxides (CO and CO2). In conventional methanol plants there is excess hydrogen in this gas stream, and in ammonia plants the carbon oxides present are not required for ammonia production and can act as poisons to downstream catalysts. After leaving the SMR in a methanol plant, the syngas mixture passes through a methanol synthesis converter loop prior to a separation stage. For ammonia production, the gas stream exiting the reformer section passes through a secondary reformer, where air is added. The gas stream then undergoes water-gas shift to reduce the level of carbon oxides, before these are removed in the carbon dioxide removal section, with residual carbon oxides being converted to methane (CH4) in the methanator before passing into the ammonia synthesis loop.
Benefits of co-production The benefits of co-production stem from the different requirements of syngas from each process. In methanol
