US Patent 7579502 Apparatus for synthesizing urea

It is intended to enable more smooth operation in an apparatus for synthesizing urea by circumventing the downward flow of a urea synthesis solution which is a gas-liquid two-phase flow and stabilizing the flow of the urea synthesis solution still remaining the gas-liquid two-phase flow and to reduce energy loss by giving smaller flow resistance. The present invention provides an apparatus for synthesizing urea including: a synthesis reactor for reacting NH3 with CO2 to obtain a urea synthesis solution containing urea, unreacted NH3, unreacted CO2, and water; a stripper for stripping the urea synthesis solution with use of at least a part of raw material CO2 to separate a gas mixture containing the unreacted NH3 and the unreacted CO2; a vertical submerged condenser having a shell and tube structure for condensing the gas mixture in an absorbing medium on the shell side while cooling the gas mixture with a cooling medium passing through the tube side; and recycling means for recycling a liquid obtained from this condenser to the synthesis reactor, wherein the synthesis reactor is a horizontal type, and wherein piping for sending the urea synthesis solution from the synthesis reactor to the stripper runs substantially horizontally and/or upward.