A process and system for treating acrylonitrile tail gas by high temperature incineration

Abstract

The invention belongs to the environmental protection technology field of organic waste gas treatment and particularly relates to a process for pretreating and burning vinyl cyanide tail gas and a system for recycling waste heat of vinyl cyanide tail gas. The system comprises a gas-liquid separation tank, an incinerator, a combustion-supporting device, an SNCR (selective non-catalytic reduction) denitrification device, a waste heat boiler, a vinyl cyanide tail gas-exhaust gas continuous heat accumulation heat exchanger, a combustion-supporting air-exhaust gas continuous heat accumulation heat exchanger, an air blower and a chimney. According to a system for treating vinyl cyanide tail gas by a high temperature burning method, hazardous substances such as vinyl cyanide, hydrocyanic acid, carbon monoxide and non-methane hydrocarbon in the vinyl cyanide tail gas can realize high temperature oxidation decomposition, and the removal rate of the hazardous substances reaches beyond 99.99%. In comparison with the traditional high temperature burning method, 60-70% of fuel consumption can be directly saved; the treating method is high-efficiency and energy-saving, and the preheating temperature is lower 20-30 degrees centigrade than the decomposition temperature of organic ingredients in the tail gas, and thus the method is safe and steady and no coking is occurred.

Description

technical field [0001] The invention belongs to the technical field of chemical organic waste gas treatment and environmental protection, and in particular relates to a system for pretreatment, incineration and waste heat recovery of acrylonitrile tail gas. Background technique [0002] Acrylonitrile tail gas refers to the exhaust gas discharged from the top of the acrylonitrile absorption tower. This type of exhaust gas is characterized by large gas volume, low calorific value, fluctuating components and high toxicity. Since the emissions of acrylonitrile, hydrocyanic acid, carbon monoxide and non-methane hydrocarbons in the tail gas exceed the national environmental protection standards, direct high-point emissions that will cause harm to the environment have been banned. [0003] The current treatment methods for this waste gas include: biological method, catalytic incineration method, high temperature incineration method. [0004] The biological method has a slow reacti...

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Problems solved by technology

[0004] The biological method has a slow reaction rate and low treatment capacity, and has high requirements for the concentration of the gas inlet and the nutrients in the absorption liquid. HCN in the waste gas is an extremely hazardous substance, which will pose a threat to the survival of microorganisms. The actual industrial application treatment effect is not ideal.

[0005] The catalytic incineration method has a high purification rate of hydrocarbons and CO, but cannot guarantee the purification efficiency of acrylonitrile and HCN, and the fluctuating calorific value of the exhaust gas or the uneven distribution of the air flow will cause local overheating, which will cause some catalysts to burn out and fail, affecting the treatment effect of exhaust gas , Increase the processing cost, and the device debugging cycle is long, and the failure rate is high

[0006] The process of the high-temperature incineration method is simple and efficient, and it has strong adaptability to the fluctuation of the flow rate and components of the acrylonitrile tail gas, and can realize the complete oxidation and decomposition of harmful substances in the acrylonitrile tail gas. High temperature, high operating cost, and acrylonitrile tail gas and combustion air contain a lot of N2, which will produce NO in the combustion process X , form secondary pollution, and increase the cost of environmental protection treatment

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