The gaseous phase C separated from the degassed liquid phase B is withdrawn from the top section 22 of decomposer 13 through nozzle 26 and pipe 27. Beilstein/REAXYS Number 3914091 . This improvement is with respect to biuret content in the degassed urea solution and the value of the heat transfer coefficient in the heat exchanger tubes, and ultimately with respect to the overall operation of the decomposer. This mixture of gas and liquid is usually delivered from the top of the heat exchanger to a separator through a pipe, which usually runs vertically upwardly from the decomposer exit, makes a bend towards the horizontal and then, either horizontally or horizontally and sloping downwardly, runs to the separator. Due to the fact that the top section 22 is now flooded with liquid and that consequently part of the degassed urea solution is back flowing into the tubes 14, 35 lbs/hr instead of lbs/hr of urea solution are now decomposed, to form 5 lbs/hr of gaseous N11,, and 30 lbs/hr of biuret. In this latter case, the liquid phase B is discharged from pipe 24 onto top tray 32 of lower tray section 33 of separator 15, and it flows downardly and countercurrently to a stream of CO introduced into separator 15 through line 34 and below bottom tray 35 of the lower tray section 33. Due to this drop in temperature, a smaller amount of gas is formed in decomposer 13. by condensing steam at I50 psig in the shell side 17 of decom poser 13. C07C 126/00 [58] Field of Search 260/555 A [56] I References Cited UNITED STATES PATENTS 3,137,725 6/1964 Cook et al. Molecular Weight 78.07 . The separated liquid phase is diverted by the deflector baffle 20 towards the top tube sheet 21 which separates the shell side 17 from the top tube side 22 of decomposer 13; this liquid phase is forced to exit the top section 22 through nozzle 23 and pipe 24. The bottom section 12 communicates with the inlets of vertical tubes 14 of decomposer 13. Siege] Attorney, Agent, or Firm-Flynn & Frishauf [57] ABSTRACT Ammonium carbamate' in an aqueous urea solution containing the carbamate, urea, water and ammonia, obtained as a urea synthesis reactor effluent is decomposed, with the formation of a liquid phase containing urea, water, residual ammonium carbamate and residual ammonia, and a gaseous phase containing ammonia, carbon dioxide and water vapor. in front of the letter e.g. The exit nozzle 23 is located in such a manner as to be as close as possible to the top tube sheet 21 of decomposer 13, for the purpose of discharging any amount of liquid from the top tube sheet 21 and thus for the purpose of preventing liquid from accumulating on the'top tube sheet 21 and from falling back into the tubes 14 through the top tube extension 25, which tubes 14 generally protude several inches above the horizontal top tube sheet 21. 4930 lbs/hr of ammonium carbamate are decomposed to form 2780 lbs/hr of gaseous CO and 2150 lbs/hr of gaseous ammonia; only 6950 lbs/hr of excess ammonia are vaporized from the urea solution and 1610 lbs/hr of water vapor are boiled off from the aqueous urea solution. Questions? PATENT OFFICE CERTIFICATE OF CORRECTION DATED December 30, 1975 |NvE 0 (5) IVO MAVROVIC It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: Column Column Column Column Column Column [SEAL] 7, line 32: after "vessel", insert which includes a heat transfer chamber 7, line 33: after "through", insert a' tube in said heat transfer chamber 7, line 33: replace "heated in a tube of said vessel to" with heated in the tube to 7, line 35: replace "wter" with water 8, line 11: after "downwardly", insert and outwardly toward the periphery of said upper section 8 line 15: replace thereby preventing substantially" with and preventing said liquid phase from accumulating in said upper section and preventing "substantially Signed and szalcd-this Twenty-fourth Day August 1976 Arrest: Owner name: