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US 11,535,586 B2Granted
Process for the synthesis of urea
AssigneeCasale SA
InventorLeonardo Marrone
Life of this patent
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Abstract
A process for synthesis of urea from CO2 and NH3 wherein a steam flow (13) produced in the condenser (3) of a high-pressure synthesis loop is compressed to raise its pressure and temperature before using the steam as a heat source for a downstream step of the process.
Claims21
A process for synthesis of urea from CO2 and NH3 comprising:
- a) reacting CO2 and NH3 at a reaction pressure to form an aqueous solution of urea;
- b) stripping said aqueous solution of urea at a stripping pressure obtaining a purified solution and a gaseous phase containing ammonia and carbon dioxide, wherein the stripping step involves passing said aqueous solution as a falling film in an externally heated tube bundle;
- c) condensing said gaseous phase in at least one condenser at a condensation pressure to form a recycle solution which is sent back to the reaction step, thus forming a synthesis loop;
- d) producing at least a first steam flow at a first recovery pressure and first recovery temperature using heat removed from said gaseous phase during the condensation step c);
- e) using said first steam flow as a heat source in at least one downstream step of the process,
- wherein:
- f) a compression of said first steam flow to reach a pressure greater than said recovery pressure and a temperature greater than said recovery temperature, before said use as a heat source in the at least one downstream step,
- wherein no fresh CO2 is added during the condensation step and wherein said step of compression of said first steam flow is performed with a compressor driven by an electric motor.
5 more elements
A plant for synthesis of urea from CO2 and NH3 comprising at least:
- a reactor where CO2 and NH3 react at a reaction pressure to form an aqueous solution of urea;
- a stripper fed with said aqueous solution of urea, wherein the solution is treated at a stripping pressure obtaining a purified solution and a gaseous phase containing ammonia and carbon dioxide, wherein the stripper includes a falling-film vertical tube bundle;
- a condenser for condensing said gaseous phase from the stripper at a condensation pressure to form a recycle solution which is sent back to the reactor, thus forming a synthesis loop;
- a steam system comprising at least a first steam line arranged to produce a first steam flow using heat removed from the condenser, wherein said first steam flow is used as a heat source in at least one downstream section of the plant;
- wherein:
- said steam system comprises a steam compressor arranged to raise the pressure of said first steam flow and deliver the so obtained compressed steam flow to said at least one downstream section, wherein said steam compressor is driven by an electric motor.
3 more elements
A method for revamping a urea plant, wherein:
- the plant comprises:
- a reactor where CO2 and NH3 react at a reaction pressure to form an aqueous solution of urea;
- a stripper fed with said aqueous solution of urea, wherein the solution is treated at a stripping pressure obtaining a purified solution and a gaseous phase containing ammonia and carbon dioxide and wherein the stripper includes a falling-film vertical tube bundle;
- a condenser for condensing said gaseous phase from the stripper at a condensation pressure to form a recycle solution which is sent back to the reactor, thus forming a synthesis loop;
- a steam system comprising at least a first steam line arranged to produce a first steam flow using heat removed from the condenser, wherein said first steam flow is used as a heat source in at least one downstream section of the plant;
- and the method includes:
- adding a steam compressor to said steam system, the added compressor being arranged to raise the pressure of said first steam flow, wherein the added compressor is driven by an electric motor.
4 more elements
Dependencies are inferred from the claim text.