On the production of LNG from coke oven gas
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Regarding the production of LNG from coke oven gas, what are the process steps involved between methane synthesis and cryogenic liquefaction? Thank you
Deamination, deacidification, dehydration, demercurization
Unlike the direct liquefaction of natural gas, in LNG production facilities using coke oven gas, ammonia is essentially removed during the debenzing stage. The heavy hydrocarbons are almost completely converted in the methanation reactor; after methanation, only trace amounts of CO2 and water, as well as trace amounts of mercury, need to be removed. Subsequent deep cooling enables the separation of nitrogen and excess hydrogen at low temperatures
Poster: The suppliers of this liquefaction technology will provide accompanying processes; the most common approach involves using an MDDA solution for washing and decarburization, followed by molecular sieve drying, mercury removal, and dust filtration before proceeding with liquefaction. Hydrogen and nitrogen are separated out in a cryogenic tank, and the resulting liquid product has a CH4 content of over 98%, which is then sent for storage
The production of LNG from coke oven gas generally includes the storage and pretreatment of coke oven gas, compression, deep purification, methanation, cryogenic pretreatment (dehydration, decarburization, demercurization, removal of heavy hydrocarbons), cryogenic liquefaction and methane-enriched gas separation, storage and replenishment of refrigerants, LNG storage tanks and loading systems, as well as utility systems (circulating water, instrument air, nitrogen, steam pipelines, flares, etc.)
Where does the ammonia come from? Before methanation, benzene and ammonia are removed, thereby removing ammonia from the system; is more ammonia generated in the methanation reactor afterward?
In the mixed gas after methanation, the main harmful substances are moisture, CO2, as well as trace amounts of mercury, dust, and acidic impurity gases. Therefore, the main processes involved are water removal, carbon removal, mercury removal, and dust removal. A cooler is used for initial water removal, a sulfur-loaded activated carbon tower for mercury removal, molecular sieves for temperature-controlled adsorption to remove CO2, moisture, and acidic gases, a dust filter, and a chilled water heat exchanger for deep cooling