How to choose the urea process technology program

At present, medium-sized urea plants in China adopt the following production processes: aqueous solution full-cycle method, medium-pressure hydrate method, carbon dioxide gas extraction method and ammonia gas extraction method.

Aqueous solution full-cycle method: this method is used in most of the small and medium-sized urea plants in China, with mature production process, convenient and reliable operation, localization of pumps and non-standard equipments, which is characterized by higher conversion rate in the synthesis tower, decomposition of unreacted materials by three-stage decompression, higher power consumption, lower pressure and temperature of the tail gas, and less danger of explosion.

Carbon dioxide gas extraction: since the 1970s, China has introduced more than a dozen sets of carbon dioxide gas extraction urea production units, mostly large-scale devices, which is characterized by a short process, low synthetic pressure, low power consumption, but harsh operating conditions, corrosion is more serious, the tail gas has the risk of combustion and explosion, the operation of a small flexible, improve the CO2 gas extraction method, the raw material gas to increase the sulfur and dehydrogenation device to reduce corrosion, reduce the risk of explosion, at the same time, the one-time investment is also a good idea to improve the CO2 gas extraction method. Danger, at the same time, the primary investment is also larger. At present, most of the large and medium-sized urea plants in China use CO2 gas extraction process.

Medium-pressure joint-urine method: this method is suitable for natural gas as raw material ammonia plant, characterized by good heat utilization, high decomposition rate, the abolition of low-pressure decomposition, simplify the process, due to the higher temperature of methyl ammonium, HO2/CO2 is lower. A ammonium pump corrosion is more serious, the pump material requirements are harsh.

Ammonia gas lift method: this method has not been localized in China, China's existing devices are imported from abroad for large and medium-sized devices, which is characterized by ammonia since the gas lift effect, so that the rate of methyl ammonium decomposition increased, thereby reducing the medium and low pressure decomposition of the recycling load, and power consumption is reduced, high-temperature and high-pressure separation of methyl ammonium, the condensation of the heat has been effectively utilized to reduce the total energy consumption, and the other operating flexibility, high operating rate, low risk of explosion, installation and installation, and the total energy consumption is reduced. In addition, the operation flexibility is large, the operation rate is high, the danger of explosion is small, the installation and maintenance are convenient, and the process condensate can be utilized twice without pollution.

In the domestic production scale in 200kt/a below urea plant generally use modified aqueous solution full cycle method production process, production scale in 300kt/a above urea plant generally use modified carbon dioxide gas extraction production process.