Low-temperature denitration process

Abstract

The invention discloses a low-temperature denitration process, which comprises the following steps: flue gas enters from the top of a reactor, mixed gas containing ammonia gas is injected into the flue gas through an ammonia injection grid, the gas flow passes through, from top to bottom, a plurality of catalyst bed layers arranged horizontally and alternately, and NOx and SOx are removed throughreaction, produced ammonium salt and dust in the flue gas are adhered on the catalyst; wherein, the catalyst bed layer consists of a reticulated conveyor belt and micro-spherical denitration catalystdeposited on the conveyor belt. The process is matched with micro-spherical low-temperature denitration catalyst with abundant macropores, nitrogen oxides and sulfur oxides in the flue gas can be effectively removed, the problem of blocking the bed layers by ammonium bisulfate is not caused, and the operation period of the device is prolonged.

Description

technical field [0001] The invention belongs to the technical field of flue gas denitrification, and in particular relates to a low-temperature denitrification process. Background technique [0002] Nitrogen oxides, collectively referred to as NOx, are one of the main sources of air pollution. The most harmful ones are: NO, NO 2 . The main hazards of NOx are as follows: (1) toxic to the human body; (2) toxic to plants; (3) can form acid rain and acid fog; (4) form photochemical smog with hydrocarbons; (5) destroy the ozone layer . [0003] Flue gas denitrification refers to the removal of NOx in flue gas. According to the treatment process, it can be divided into wet denitrification and dry denitrification. Mainly include: acid absorption method, alkali absorption method, selective catalytic reduction method, non-selective catalytic reduction method, adsorption method, plasma activation method, etc. Some researchers at home and abroad have also developed a method of usi...

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Problems solved by technology

[0008] 2. The NOx content in the flue gas is related to the process conditions of the main device, and the fluctuation range is relatively large. However, the catalyst amount of the SCR fixed bed reactor is fixed. Once the NOx concentration range exceeds the design value, the NOx of the purified flue gas cannot Discharge

Therefore, the operating flexibility of the fixed bed is less

[0009] 3. During the operation of the fixed-bed reactor, the activity of the catalyst gradually decreases. When the NOx at the outlet of the reactor cannot meet the standard discharge, the catalyst needs to be replaced

It can be seen that the utilization rate of the catalyst in the fixed bed SCR reactor is too low

[0010] 4. After denitrification of flue gas, wet scrubbing and dust removal should be used together with desulfurization. The desulfurization waste liquid generated in the desulfurization and dust removal process also needs to be separated from liquid to solid. The process is long, the operation is complicated, and the investment and operation costs are high.

[0011] At present, there is no industrialized moving bed SCR reactor in the world. CN102008893A introduces a traditional moving bed reactor for SCR reaction. Since the flue gas needs a pressure drop when passing through the bed, it is not suitable for large amount of flue gas and flue gas. Working conditions with medium dust and low residual pressure of flue gas

And the catalyst moves downward by gravity. When the reactor is large, there is a problem of uniformity of movement, and the bed is easy to bridge and block. The requirements for the particle size of the catalyst are relatively high, and there are also problems with the uniformity of the reaction.

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