The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 16, 1976
Filed:
Jan. 28, 1974
Shigeru Inoue, Kamakura, JA;
Tetsuo Kimura, Kamakura, JA;
Mitsui Toatsu Chemicals, Inc., Tokyo, JA;
Abstract
Unreacted ammonium carbamate contained in urea synthesis effluent obtained by reacting ammonia and carbon dioxide at urea synthesis pressures and temperatures is recovered by a method comprising subjecting the urea synthesis effluent to a three-stage decomposition to decompose the unreacted ammonium carbamate in each stage, the first stage and the second stage of which are operated at a gauge pressure of at least 30 kg/cm.sup.2 and a gauge pressure of from 10 to 25 kg/cm.sup.2, respectively, absorbing the off-gas resulting from the second stage decomposition in an absorbent to form an aqueous solution of ammonium carbamate and unabsorbed gaseous ammonia, condensing the gaseous ammonia to form recovered liquid ammonia, and absorbing substantially all of the off-gas resulting from the first stage decomposition in the aqueous solution of ammonium carbamate to form recovered ammonium carbamate solution while removing the heat of absorption by indirect heat exchange with the recovered liquid ammonia pressurized to the urea synthesis pressure.