Tripolycyanamide whole circulation production process and device

Abstract

The invention provides a tripolycyanamide whole circulation production process and device. Liquid urea is used as a raw material to be fed into a tripolycyanamide reactor; tripolycyanamide, ammonia and carbon dioxide gas mixture material gas is generated; after the cooling and purification separation, the tripolycyanamide is subjected to desublimation to form a solid phase in a chiller to realizethe gas-solid separation in an efficient separator; the tripolycyanamide is fed into a packaging system; gas containing ammonia and carbon dioxide and separated from the efficient separator enters a combined efficient washing cooling tower; one path of gas subjected to washing, cooling and temperature lowering is pressurized to enter the tripolycyanamide reactor; one path is subjected to liquid urea synthesis through an efficient synthesis urea conversion system and then enters the tripolycyanamide reactor for repeated production of the tripolycyanamide product. The tripolycyanamide productionprocess has the advantages that tripolycyanamide process tail gas cannot be discharged to a position outside a tripolycyanamide production device boundary region; the tripolycyanamide process tail gas realizes the self circulation utilization inside the tripolycyanamide process production device boundary region; the device belongs to a clean environmental-friendly device; the total efficient circulation utilization of the tripolycyanamide process tail gas in the tripolycyanamide process production device can be realized.

Description

technical field [0001] The invention relates to the field of melamine preparation, in particular to a brand-new melamine full-cycle production process and device. Background technique [0002] The existing melamine production process and devices all take the external supply of urea or liquid urea as raw material, enter the fluidized bed reactor, and react to generate melamine, ammonia and carbon dioxide gas at 350-420°C and 0-0.7MPa pressure, from The material gas from the reactor enters the hot gas cooler, and the process gas is cooled by Daosheng, so that the high boiling point by-products are crystallized out as solids, and the cooled process material gas enters the hot gas filter to filter the solid impurities in the gas, and the filtered gas Entering the crystallizer and the process cold air from the liquid urine washing system are reversely contacted for heat exchange, melamine is precipitated from the process material gas in the form of solid, and then the gas contain...

AI Technical Summary

Problems solved by technology

[0007] The third is that the melamine process tail gas needs to be sent to the melamine process tail gas absorption treatment device or external discharge device outside the boundary area, which increases the investment cost of tail gas treatment, and these tail gases are mostly used to produce ammonia water with low added value, ammonium bicarbonate, liquid ammonia, nitric acid Base compound fertilizer, soda ash, etc.

[0008] Fourth, even if the tail gas of the melamine process is sent to the original urea production device of the enterprise to produce urea after absorption and treatment, it will cause the reduction of the urea conversion rate of the original urea production device of the enterprise, the reduction of the urea production capacity and the substantial increase in the energy consumption of urea. The increase and the unstable operation of the company's original urea plant have greatly increased the management difficulty of the company's original urea production plant

[0009] Fifth, a large amount of waste residue, waste gas, and waste water will be generated during the operation of the independent melamine process production device and melamine process tail gas treatment device. If treatment is required, repeated investment in new waste residue, waste gas, and waste water environmental protection treatment facilities is required, and the treatment effect is not ideal. It is also impossible to recycle resources

Moreover, it wastes investment and complicates the entire production process chain process, equipment, and system complexity, which is not conducive to safety production management and production environmental protection management.

[0010] Sixth, due to the complex and cumbersome process of the entire production process chain, there are too many operators in the equipment area, and there are too many hidden dangers in production safety, which cannot effectively control the production of safety and environmental protection

[0011] The above not only increased the investment of the melamine process tail gas treatment device, but also increased the difficulty factor of unsafe and environmentally friendly production of melamine production and other devices. Stable operation or production shutdown will cause the process tail gas to be vented and the environmental protection will not meet the standards, and the economic benefits of the long-term stable operation of the melamine process production unit will not be brought into play.

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