Reduced energy consumption ammonia synthesis - where synthesis gas mixt. is produced by partial oxidn. followed by removal of carbon oxide(s) and water from gaseous effluent

摘要

(i) Air and hydrocarbon streams are reacted at 35-150 bar in a first partial oxidn. zone contg. a catalyst to produce a gas mixt. contg. H2, N2, H2O, carbon oxides, inert gas and unreacted hydrocarbon; temp. at the zone exit is 850-1200 deg.C. (ii) CO in the mixt. is then shift converted into a CO2 plus H2 mixt. (iii) CO2 and H2O is removed from the mixt. obtd. in (ii) and the resulting synthesis gas mixt. obtd. is (iv) fed to a second zone for partial conversion of N2 and H2 to NH3. (v) NH3 is sepd. from the gas effluent from the zone and the gas mixt. remaining is at least partially recycled. Amt. of air fed to zone in (i) must ensure that the H2:N2 molar ratio in the mixt. obtd. in (ii) is 2.5-3:1; additional O2 is also fed to the first zone to effect the required degree of hydrocarbon conversion.