Melamine production device and production technology

Abstract

The invention relates to a melamine production device and a production technology, belonging to the technical field of preparation of melamine. According to the melamine production device, gas discharged from a trap is not subjected to scrubbing cooling but directly enters a carrier gas compressor to be boosted after impurities such as dust are separated by virtue of a gas-solid separator, and then the gas is subjected to heat exchange by virtue of a carrier gas heater and reaction gas from a hot gas filter and then enters a reactor; meanwhile, the other part of gas is boosted by virtue of a cold air blower and then returns to a crystallizer to be taken as quenching gas and used for crystallization of melamine, and the cold gas and the hot gas are reasonably utilized, so that consumption and waste of energy in a melamine production process are greatly reduced; the production technology provided by the invention is simple in process, and energy is reasonably utilized; and a melamine device with the capacity of fifty thousand tons per year can save about 3000-5000 tons coal per year, and on the basis, the cold air blower can save electricity by about 0.25-0.40 million kwh per year.

Description

technical field [0001] The invention belongs to the technical field of melamine preparation, and in particular relates to a melamine production device and an energy-saving low-pressure method for preparing melamine. Background technique [0002] At present, the domestic low-pressure melamine production process uses urea as raw material. The process flow is described as follows: molten urea is pumped to the urea inlet of the reactor, atomized under the action of atomizing gas and enters the reactor. Under the gauge pressure of 0.2-0.6MPa and high temperature of 350-420°C, the catalyst (usually silica gel or silica-alumina gel) will react to produce melamine, ammonia, and carbon dioxide. The heat required for the reaction is provided by a molten salt system. The carrier gas of the reactor is the mixed gas of ammonia and carbon dioxide after boosted by the carrier gas compressor. After the reaction, the gas products, by-products and carrier gas pass through the inner cyclone ...

AI Technical Summary

Problems solved by technology

[0003] The gas coming out from the top of the finished cyclone separator contains a small amount of triamine dust and unreacted urea, and enters the liquid urine washing tower. After being washed, purified and cooled by liquid urine, the temperature drops to 132-150 ° C and divided into three ways: The first path is boosted by the carrier gas compressor and then used as the carrier gas of the reactor after being heated by its preheater, the second path is boosted by the air-conditioning fan and then returned to the crystallizer as quenching air, and the third path enters the tail gas system (see the manual attached figure 1 ); but the disadvantage of this process is that the use of heat is unreasonable: (1) the temperature of the carrier gas needs to be heated from 132-150 °C to 350-420 °C with molten salt before entering the reactor, which requires the consumption of molten salt furnace A large amount of heat increases coal consumption; (2) The temperature of the reaction gas entering the crystallizer is 320-350°C, and the temperature of the process gas is relatively high. The air volume of the fan is large, generally 4-5 times that of the air carrying capacity, which results in a high power consumption of the air-conditioning fan, resulting in a waste of energy

[0004] In summary, the existing melamine production process and equipment still have problems such as high energy consumption, serious energy waste, and inability to be effectively recycled. Therefore, it is necessary to study a more energy-saving melamine production process

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