Patent ID: 7052655

Claim:
A urea synthesis apparatus, comprising (a) a vertical condensation and synthesis column which comprises a cooler in a portion extending from a bottom part to a middle part of the column and a synthesis portion extending from the middle part of the column to the top portion of the column; (b) a stripper for separating unreacted ammonia and unreacted carbon dioxide from a urea synthesis solution comprising urea, unreacted carbon dioxide, unreacted ammonia, and water, thereby providing a mixed gas comprising ammonia, carbon dioxide and water; (c) a pipe for supplying liquid ammonia to a bottom part and a middle part of the vertical condensation and synthesis column, (d) a pipe having a first open end disposed in a top part of the vertical condensation and synthesis column and a second open end connected to a top part of the stripper, whereby the urea synthesis solution is transferred from the vertical condensation and synthesis column to the stripper; (e) a pipe for introducing carbon dioxide into a bottom portion of the stripper; (f) a pipe connecting a top portion of the stripper to a bottom portion of the vertical condensation and synthesis column for transferring the mixed gas from the stripper to the vertical condensation and synthesis column; (g) a scrubber disposed in a top part of the vertical condensation and synthesis column, whereby ammonia and carbon dioxide are absorbed in an absorbing medium; (h) a pipe connected to the top of the scrubber for discharging unabsorbed gas; (i) a pipe having a first open end disposed in the scrubber and a second open end connected to a bottom portion of the vertical condensation and synthesis column, whereby the absorbing medium and absorbed ammonia and carbon dioxide are transferred from the scrubber to the bottom portion of the vertical condensation and synthesis column; and (j) a pipe for discharging an aqueous solution comprising urea and unreacted ammonia and unreacted carbon dioxide from a bottom portion of the stripper.