Catalytic synthesis of ammonia from nitrogen and hydrogen - using heat exchanger tubes in reactor to increase yield

摘要

The yield is increased during the catalytic synthesis of NH3 in high pressure reactors, using heat exchange inside the reactor with the incoming synthesis gas mixt. of N2 and H2, which is preheated to min. 370-390 degrees C and first adiabatically reacted using catalyst grain size 3-6 mm. to obtain an initial ammonia concn. which is 0.53-0.4 times the final concn. By cooling in a tubular heat exchanger system, using 12-20 vol.% NH3, a synthesis gas temp. (SGT) is obtd. 85-65 degrees C lower than the local equilibrium value (LEV); and with over 20 vol.% NH3, an SGT is obtd. 55-35 degrees C lower than the LEV, and which is held constant. Intensive cooling pref. reduces the reacted gas temp. after each contact stage to 370-430 degrees C. A given reactor can produce more NH3 in a given time than in conventional processes.