Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Patent
1974-03-20
1977-03-22
Vertiz, Oscar R.
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
423359, C07C12600
Patent
active
040137180
ABSTRACT:
Urea is produced through an integrated, isobaric process in which raw ammonia synthesis gas, consisting essentially of H.sub.2, N.sub.2 and sufficient CO.sub.2 to produce the urea and compressed to a pressure slightly above the urea synthesis pressure, is decarbonated in a vertical film heat exchanger where it is contacted with a thin aqueous film containing NH.sub.3 with which the CO.sub.2 reacts to produce a concentrated carbamate solution that is withdrawn from the bottom of the exchanger and fed to a urea reactor. The compressed, unreacted synthesis gas containing traces of CO and saturated with NH.sub.3 is withdrawn from the upper part of the heat exchanger, NH.sub.3 is separated therefrom and recycled to the heat exchanger, and the balance of the unreacted synthesis gas is subjected to methanation to eliminate any CO and CO.sub.2 therein. The methanated gas and the gases from an ammonia synthesis reactor are fed to the lower part of a vertical film absorber where they meet, in counter-current, a film of water or a dilute solution of NH.sub.3, fed to the top of the film absorber, which absorbs the NH.sub.3 in the gases. A concentrated NH.sub.3 solution, withdrawn from the film absorber as bottom product, is fed to the vertical film heat exchanger at vertically spaced points and heat is wit-drawn from that exchanger at a rate that is regulated to maintain the temperature in the heat exchanger above the carbamate crystallization temperature. Synthesis gas is withdrawn from the top of the film exchanger, cooled to condense a dilute NH.sub.3 solution that is withdrawn, additionally cooled and dried through treatment with liquid ammonia in a Venturi tube, and then fed to an ammonia synthesis reactor. A solution of urea, carbamate and excess NH.sub.3 flows from the urea reactor to a carbamate decomposer from the top of which carbamate decomposition products flow directly to the urea reactor, and an aqueous urea solution and equilibrium NH.sub.3 are withdrawn from the bottom of the carbamate decomposer.
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Guadalupi Mario
Pagani Giorgia
Paris Ivo
Zardi Umberto
Snam Progetti S.p.A.
Vertiz Oscar R.
Watson Ralph M.
Wheelock Eugene T.
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