Nitric acid tail gas denitration method

Abstract

The invention belongs to the technical field of nitric acid production devices and discloses a nitric acid tail gas denitration method. The method comprises: injecting purge gas of an ammonia tank forammonia synthesis as a reducing agent into nitric acid tail gas at a certain temperature (depending on the initial activation temperature of the catalyst), carrying out uniform mixing, feeding the mixture into a denitration reactor, wherein hydrogen reacts with oxygen to form water and gas ammonia decomposes NOx in the exhaust gas into nitrogen gas and water vapor that are environmentally friendly, and discharging the gas into air. The reducing agent is purge gas of the ammonia tank for ammonia synthesis so that the difficulty and energy consumption of the purge gas recovery are reduced and the raw material ammonia use is reduced. The ammonia gas easily reacts with oxygen so that the catalyst can be activated at a lower temperature the selective reaction of ammonia and NOx is easy. The purge gas pressure is higher than the pressure of nitric acid tail gas and is stable so that the compression or pressurized vaporization process required for the use of the gas ammonia is avoided. The whole process reduces an investment, is stable in operation, realizes a low operation cost and has good emission reduction effects.

Description

technical field [0001] The invention belongs to the technical field of nitric acid production devices, in particular to a nitric acid tail gas denitrification process. Background technique [0002] The nitric acid industry in the chemical industry is highly polluting. China has become the world's largest producer of nitric acid, so pollution control and environmental management have also been developed and valued. In the production process of nitric acid, NOx emissions are large, and nitrogen oxides are one of the causes of air pollution. Excessive NOx emissions will inevitably cause environmental damage and harm to human body, so the prevention and control of NOx pollution is very important. [0003] At present, there are many methods to choose from for NOx denitrification of emissions after the production of nitric acid, but considering many factors such as simple operation, stable effect, long service life, cost, energy saving, etc., it is difficult to use selective ca...

AI Technical Summary

Problems solved by technology

However, the existing selective catalytic reduction reaction (SCR method) uses gaseous ammonia as a reducing agent, consumes gaseous ammonia as a raw material, and because of the small flow rate of gaseous ammonia, it is prone to local uneven mixing, resulting in local NH 3 The / NOx molar ratio is not appropriate, which directly affects the emission reduction effect and increases the ammonia consumption of the system

In addition, since the pressure levels of the gas ammonia used in the nitric acid plant and the gas ammonia used for emission reduction are inconsistent, additional devices (such as ammonia compressors or pressurized ammonia distillation devices) need to be added to provide higher pressure gas ammonia, resulting in increased production costs

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