Apparatus for synthesizing urea and method for revamping the same

A method for revamping an existing apparatus for synthesizing urea having a synthesis reactor for reacting ammonia with carbon dioxide to obtain a urea synthesis solution containing urea, unreacted ammonia, unreacted carbon dioxide and water, comprising:

• installing the apparatus with:
• a stripper for stripping the urea synthesis solution with use of at least a part of raw material carbon dioxide to separate a gas mixture containing the unreacted ammonia and the unreacted carbon dioxide;
• 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 the vertical submerged condenser to the synthesis reactor,
• wherein the vertical submerged condenser is placed below the synthesis reactor.

A method for revamping an existing apparatus for synthesizing urea having

• a synthesis reactor for reacting ammonia with carbon dioxide to obtain a urea synthesis solution containing urea, unreacted ammonia, unreacted carbon dioxide and water;
• a stripper for stripping the urea synthesis solution with use of at least a part of raw material carbon dioxide to separate a gas mixture containing the unreacted ammonia and the unreacted carbon dioxide;
• and
• a vertical falling liquid film condenser for condensing the gas mixture;
• comprising installing the apparatus with:
• 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 the vertical submerged condenser to the synthesis reactor,
• wherein the vertical submerged condenser is placed below the synthesis reactor.

A method for synthesizing urea using an apparatus having a synthesis reactor for reacting ammonia with carbon dioxide to obtain a urea synthesis solution containing urea, unreacted ammonia, unreacted carbon dioxide and water, comprising:

• stripping by a stripper the urea synthesis solution with use of at least a part of raw material carbon dioxide to separate a gas mixture containing the unreacted ammonia and the unreacted carbon dioxide;
• condensing by a vertical submerged condenser having a shell and tube structure, 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 a liquid obtained from the vertical submerged condenser to the synthesis reactor,
• wherein the vertical submerged condenser is placed below the synthesis reactor.