Feedstock economics

摘要

Various feedstock options are available for those wishing to make syngas, from steam reforming or partial oxidation of natural gas through gasification of various heavy feedstocks such as coal, heavy fuel oils, petroleum coke, biomass or industrial waste, and reforming of naphtha. Hydrogen can also be electrolytically split from water as a source for ammonia production. However, as the International Fertilizer Industry Association's (IFA's) most recent survey of ammonia capacities shows (Figure 1), coal and natural gas are by far the most prevalent. The small remaining naphtha capacity is exclusively in India, and those plants are now in the process of conversion to natural gas feed because of the relatively high cost of naphtha, and the fuel oil plants are generally smaller and older facilities. There are a couple of plants with the capacity for hydrogen generation from electrolysis, but they are mostly closed down due to the relatively high cost of electricity and the requirement for the power to be used for domestic rather than industrial uses. Generation from industrial waste, biomass or alternative energy sources is still in its infancy. Of the coal-based capacity, there are some isolated coal-based plants in Japan, Vietnam, South Africa and the US, as well as a couple of plants based on petroleum coke gasification (e.g. Coffeyville in Kansas), but by and large coal-based ammonia is a Chinese phenomenon, with 95% of coal-based capacity located there.