Long-period energy-saving melamine production system

Abstract

The invention belongs to the technical field of melamine production and in particular relates to a long-period energy-saving melamine production system. The melamine production system comprises a reactor, a hot gas exchanger, a hot gas separator, a crystallizer, a finished cyclone separator, a tail gas exchanger and a tail gas separator connected in sequence, wherein the reactor is connected witha quick melting kettle; and the hot gas separator and the tail gas separator are respectively connected with slag pots. Compared with other processes, the melamine production system disclosed by the invention has the advantages that a liquid urine washing system is removed, standby equipment of a hot gas cooler and a filter is reduced, and investment is less; long-period stable operation is realized, and the period can reach one year or longer; a liquid urine pump, an air-cooling fan and other equipment are reduced, and due to simplified process procedures and an optimized energy conversion scheme, the process energy consumption is low; the energy consumption of ammonia back-flushing is greatly reduced, and the production cost is reduced; the tail gas is clean, equipment corrosion and wallscales can be reduced, and the influence of entrainments on later sections during tail gas utilization can be reduced; and diphenyl ether is not used in the hot gas cooling system, and production ofsolid wastes such as filter bags and the like is reduced.

Description

technical field [0001] The invention belongs to the technical field of melamine production, and in particular relates to a long-period energy-saving melamine production system. Background technique [0002] Melamine production processes mainly include Ouzhi high pressure method, DSM low pressure method, and BASF atmospheric pressure gas phase extraction cooling method. Ouzhi high pressure method and DSM low pressure method are stable in operation and good in product quality, but have huge investment and high energy consumption; BASF atmospheric pressure method The gas-phase extraction cooling process and China's improved pressurized gas-phase extraction cooling process have small investment, short process and low energy consumption, but the operation cycle is short, and the product quality fluctuates greatly due to the impact of stopping feeding. [0003] At present, the domestic production of melamine mainly adopts the BASF atmospheric pressure gas-phase extraction cooling ...

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Problems solved by technology

[0002] Melamine production processes mainly include Ouzhi high pressure method, DSM low pressure method, and BASF atmospheric pressure gas phase extraction cooling method. Ouzhi high pressure method and DSM low pressure method are stable in operation and good in product quality, but have huge investment and high energy consumption; BASF atmospheric pressure method The gas-phase extraction cooling process and China's improved pressurized gas-phase extraction cooling process have small investment, short process and low energy consumption, but the operation cycle is short, and the product quality fluctuates greatly due to the impact of stopping feeding.

[0003] At present, the domestic production of melamine mainly adopts the BASF atmospheric pressure gas-phase extraction cooling process. In this process, there is fouling of the hot gas cooler tube bundle, periodic switching of standby equipment, and inspection and maintenance of fouling equipment; poor filtration accuracy and efficiency of hot gas filters affect product quality. The surface of the filter bag is clogged and the standby equipment is periodically switched; the melamine wall on the top of the crystallizer 5 causes landslides, affects product quality, and in severe cases leads to problems such as paralysis of the discharging equipment

[0004] In the existing process, the hot gas cooler uses raw oil as the heat exchange medium. The physical and chemical properties of raw oil are toxic, volatile, flammable and explosive, and there are dangers and environmental protection risks in use.

[0005] The above problems have seriously restricted the long-term stable operation level of melamine production. The operation cycle is basically 1-3 months. During the inspection and maintenance process, a large number of work such as unblocking, replacement, and cleaning will be caused. The consumption of auxiliary materials is large, and the labor intensity of workers Large, producing a lot of ground melamine and solid waste

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