A process for synthesis of urea from CO.sub.2 and NH.sub.3 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.

A process for synthesis of urea from CO.sub.2 and NH.sub.3 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.

A urea production process which includes and a synthesis section, a recovery section and evaporation section and a finishing section wherein the evaporation section includes a first evaporator and downstream thereof a second evaporator for urea solution. The second evaporator operates a lower pressure than the first evaporator to provide a urea melt and second vapor, solidifying the urea melt in a finishing section to provide a solid urea produce and off gas, scrubbing the off gas followed by condensing to produce a first condensate and second condensate; supplying the first condensate to a wastewater treatment section and supply the second condensate to the scrubber wherein the second condensate is used as a scrub liquid in the scrubber.

A urea production process which includes and a synthesis section, a recovery section and evaporation section and a finishing section wherein the evaporation section includes a first evaporator and downstream thereof a second evaporator for urea solution. The second evaporator operates a lower pressure than the first evaporator to provide a urea melt and second vapor, solidifying the urea melt in a finishing section to provide a solid urea produce and off gas, scrubbing the off gas followed by condensing to produce a first condensate and second condensate; supplying the first condensate to a wastewater treatment section and supply the second condensate to the scrubber wherein the second condensate is used as a scrub liquid in the scrubber.

A process for the production of feed grade urea starting from a liquid urea melt, the process comprising processing the urea melt (6) to promote the formation of biuret until a concentration of at least 3% biuret, and subjecting the so obtained biuret-containing urea melt (8) to a shaping process to obtain a granular urea product.

A process for the production of feed grade urea starting from a liquid urea melt, the process comprising processing the urea melt (6) to promote the formation of biuret until a concentration of at least 3% biuret, and subjecting the so obtained biuret-containing urea melt (8) to a shaping process to obtain a granular urea product.

Combined apparatus (1) for the synthesis of urea from ammonia and carbon dioxide, comprising an internal wall (3) which delimits two coaxial zones (4) inside the apparatus, operating respectively as reaction (4) and condensation (5) zones, and optionally also comprising a stripping zone and/or a scrubber integrated in the same apparatus.

A urea production process comprises a step of synthesis of urea by reaction of ammonia and carbon dioxide, where at least part of the carbon dioxide for the urea reaction synthesis is produced in an oxy-combustion process; the oxy-combustion process is specifically a flameless oxy-combustion process.

A urea production process comprises a step of synthesis of urea by reaction of ammonia and carbon dioxide, where at least part of the carbon dioxide for the urea reaction synthesis is produced in an oxy-combustion process; the oxy-combustion process is specifically a flameless oxy-combustion process.

The present invention discloses a method for recycling urea in the process of separating and purifying unsaturated substances through a urea adduction method. The method comprises the following steps: liposoluble substances containing target unsaturated components are used as raw materials, and subjected to urea adduction, crystallization and filtration to produce a filtrate, from which the specific unsaturated components are obtained; the urea adduct is dissolved in a polar solvent, and after the adducted adducts are layered and released, adding a certain solvent to the urea solution to adjust the polarity, then cooling for crystallization, and recycling the urea. The method can realize complete release of the adducted components and recycling and reuse of urea, and the process is simple, the recovery rate is high, and the adduction effect is not influenced when recycling urea for reuse, and the production cost of the urea adduct is reduced, thus alleviating the adverse impact of urea discharges on the environment.