Urea synthesis with improved heat recovery and conversion

Claim 1

In a urea synthesis process wherein fluid NH 3 , fluid CO 2 and an aqueous solution comprising ammonium carbamate are contacted at elevated pressure and elevated temperature to form a total urea synthesis mixture in a urea synthesis reactor to form urea, the improvement which comprises charging reactor feed streams of fluid NH 3 , fluid CO 2 and an aqueous solution comprising ammonium carbamate to a lower portion of said reactor having an indirect heat exchange means positioned therein which extends from the lower portion to the upper portion of the reactor, said heat exchange means including a heat exchange medium and including a first header positioned in the upper portion of the reactor, a second header positioned in the lower portion of the reactor and conduit means in said reactor interconnecting said headers for passing heat exchange medium therebetween, imparting heat of reaction of said NH 3 , CO 2 and ammonium carbamate mixture to said heat exchange medium in said second header at the lower portion of said reactor, and passing the resulting reaction mixture and said heat exchange medium to the upper portion of said reactor, said heat exchange medium being so passed through said conduit means to said first header, whereby heat of said heat exchange medium is transferred to said reaction mixture as it is passed from the lower portion to the upper portion of said reactor.