Urea synthesis process

Claim 1

UREA SYNTHESIS PROCESS WITH TOTAL RECYCLE OF UNCONVERTED PROCESS COMPONENTS WHICH COMPRISES COMPRESSION INPUT STREAMS OF AMMONIA AND CARBON DIOXIDE TO UREA SYNTHESIS PRESSURE IN THE RANGE OF 2000 P.S.I.G. TO 6000 P.S.I.G. COMBINING SAID INPUT STREAMS WITH A GASEOUS RECYCLE STREAM WHEREBY SAID CYCLE STREAM IS QUENCHED AND A COMBINED UREA SYNTHESIS STREAM IS FORMED AT A TEMPERATURE IN THE RANGE OF 350*F. TO 600*F., COOLING SAID COMBINED STREAM IN HEAT EXCHANGE WITH LIQUID WATER TO A TEMPERATURE IN THE RANGE OF 300*F. TO 400*F., WHEREBY SAID WATER IS VAPORIZED TO STEAM AND A PORTION OF SAID COMBINED STREAM IS CONVERTED TO UREA, REDUCING THE PRESSURE OF THE RESULTING STREAM TO THE RANGE OF 1200 P.S.I.G. TO 1700 P.S.I.G., REMOVING A FIRST OFF-GAS COMPRISING UNCONVERTED AMMONIA AND CARBON DIOXIDE TOGETHER WITH WATER VAPOR, REDUCING THE PRESSURE OF THE RESIDUAL STREAM TO THE RANGE OF 600 P.S.I.G. TO 850 P.S.I.G., HEATING THE RESIDUAL STREAM TO FURTHER DECOMPOSE AMMONIUM CARBAMATE, REMOVING A SECOND OFF-GAS COMPRISING AMMONIA, CARBON DIOXIDE AND WATER VAPOR, REDUCING THE PRESSURE OF THE RESIDUAL STREAM TO THE RANGE OF 275 P.S.I.G. TO 500 P.S.I.G., HEATING THE RESIDUAL STREAM AND REMOVING A THIRD OFF-GAS COMPRISING OF AMMONIA, CARBON DIOXIDE AND WATER VAPOR, REDUCING THE PRESSURE OF THE RESIDUAL STREAM TO THE RANGE OF 5 P.S.I.G. TO 50 P.S.I.G., REMOVING A FOURTH OFF-GAS COMPRISING AMMONIA, CARBON DIOXIDE AND WATER VAPOR, ABSORBING SAID FOURTH OFF-GAS IN AQUEOUS ABSORBENT SOLUTION, COMBINING THE RESULTING SOLUTION WITH SAID RESITUAL STREAM AT A PRESSURE IN THE RANGE OF 275 P.S.I.G. TO 500 P.S.I.G., COMPRESSING SAID THIRD OFF-GAS TO THE PRESSURE LEVEL OF SAID SECOND OFF-GAS AND COMBINING SAID GAS STREAMS, COMPRESSING THE COMBINED GAS STREAM TO THE PRESSURE LEVEL OF SAID FIRST OFF-GAS AND COMBINING SAID GAS STREAMS, COMPRESSING THE TOTAL COMBINED GAS STREAM TO UREA SYNTHESIS PRESSURE TO FORM SAID GASEOUS RECYCLE STREAM, COOLING SAID COMBINED GAS STREAMS DURING COMPRESSION BY HEAT EXCHANGE WITH SAID STEAM GENERATED BY HEAT EXCHANGE DURING UREA SYNTHESIS, WHEREBY SAID STREAM IS SUPERHEATED, AND EXPANDING SAID SUPERHEATED STEAM THROUGH POWER GENERATING MEANS COMBINED WITH MEANS FOR SAID COMPRESSION OF OFF-GAS WHEREBY POWER DERIVED FROM STEAM EXPANSION IS UTILIZED IN OFF-GAS COMPRESSION.