MODERNIZATION OF PLANTS FOR COMBINED SYNTHESIS OF AMMONIA AND UREA Russian patent published in 2024 - IPC B01J19/24 C01C1/04 C07C273/04 

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of upgrading a combined synthesis of ammonia and urea, which includes an ammonia section, a urea section and a steam network, as well as a method of combined production of ammonia and urea. In the modernization method, the ammonia section includes a head section for generating make-up synthesis gas by reforming a hydrocarbon and an ammonia synthesis section in which the make-up synthesis gas is reacted to produce ammonia. Obtained ammonia and at least a portion of CO₂ removed from the make-up synthesis gas in the head section are fed into the urea section for use as a starting material for producing urea. Urea section includes a high-pressure urea synthesis section, including at least a urea synthesis reactor, a stripper for removing unconverted ammonia and carbon dioxide from the reactor effluent, a condensation stage configured to condense the stripper vapours containing ammonia and carbon dioxide, removed from the reactor effluent, as well as a regeneration section for regeneration of unconverted ammonia and carbon dioxide from the effluent solution of the stripping apparatus at a pressure below the urea synthesis pressure. Steam network comprises steam generators and steam consumers, and steam generated in ammonia section is transferred to urea section and directed to at least one steam consumer in urea section. High-pressure urea synthesis section condensation stage is a steam generator in the steam network and generates low pressure steam at a first pressure, using the steam condensation heat of the stripper, wherein low pressure steam is used inside urea section in one or more steam consumers of urea section. Modernization includes provision of low pressure steam transfer at pressure not higher than 6 bar rel. from ammonia section to urea section for use in at least one steam consumer in urea section.

EFFECT: providing more efficient use of steam and integration of steam networks in plants for combined synthesis of ammonia and urea.

19 cl, 6 dwg