Vaporizing system vacuumizing method for urea production

Abstract

The invention discloses a process for evacuation of vaporization system in urea production, characterized in that, a closed cycle apparatus is arranged which comprises a pump, a liquid-gas injector and a circulation groove connected in turn through pipes, and urea and ammonium carbonate liquid is used as circulation media to carry out evacuation for urea vaporization system. The beneficial effects of the invention are low energy consumption, high degree of vacuum, ammonia reclamation capability and reduced environmental pollution.

Description

technical field [0001] The invention belongs to a urea production method, in particular to a vacuuming method for a urea evaporation system. Background technique [0002] At present, there are more than one hundred small urea production enterprises in the country, all of which adopt the general design of the aqueous solution full circulation process. The vacuuming of the evaporation system is to use 1.275Mp (absolute) medium pressure steam, and the negative pressure is formed by the evaporation injector to realize the vacuuming. Vacuum, this process technology is mature and reliable, but it consumes a lot of steam and consumes a lot of energy. Moreover, the ammonia-containing steam after vacuuming is directly vented, which not only fails to recover the ammonia in the tail gas, but also pollutes the environment. [0003] Therefore, some enterprises try to reduce energy consumption through technological transformation without using steam. The technical solutions are similar, ...

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Problems solved by technology

The disadvantage is that the potential energy of the potential difference of the cooling circulating water is used to evacuate, the pressure difference is limited, and the ejector has not been improved, and some ejectors are not used, so the vacuum degree is not high and the effect is not very good; more importantly, the exhaust gas The ammonia dissolved in the circulating water will corrode all the equipment using cooling water and reduce the service life; at the same time, the ammonia in the circulating water will volatilize and destroy the air quality in the factory area; when the ammonia concentration in the circulating water is too high, it must be discharged and replaced. Can neither recycle ammonia, but also pollute the environment, it can be said that the loss outweighs the gain

Therefore, some enterprises stopped using it and resumed the original steam vacuuming process, causing unnecessary losses

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