A Hungarian (Pet) 480-t/day NH3 reactor was installed to replace the former 7 small reactors of the 1920s. It was modernized to yield 500 t NH3/day at a pressure reduced from 350 to 295 bar, gas How rate lowered from 250,000 to 239,200 m(3) (S.T.P.)/h. The final temperature of ammonia separation was lowered from 16 to 5degreesC (with 5.1 mol% NH3 in recycled gas reduced to 3.8), Tarnow's PS3 catalyst was used, particle size 6-10 mm from top down to 5 m and 5-8 mm further to the bottom of the bed, and a double water cooling system was applied. Total energy consumption was reduced from 40 to 32-34 GJ/t NH3.