Two-step oxidation-reduction flue gas denitration method

Abstract

The invention discloses a two-step oxidation-reduction flue gas denitration method which comprises an ozone oxidation device 1, an ozone generator 9, an ozone adding control system 10, an NO / NOx sensor 8, a reduction reaction tower 2, an absorption liquid recovery pool 3, a reducing agent absorption liquid circulation pool, a reducing agent solution preparation device 6, a reducing agent solution adding device 7 and a circulating pump system 5. Firstly, flue gas to be treated enters the ozone oxidation device; under the action of ozone, part of NO in the flue gas is oxidated into NO2; afterwards, the flue gas is conveyed into the reduction reaction tower to be in contact with reducing agent solution; and under the action of reducing agents, most of NO and NO2 in the flue gas are reduced into N2, so that the purpose of denitration and purification of the flue gas can be achieved. Waste water generated after flue gas denitration reaction can be reclaimed and reused. The method provided by the invention accomplishes flue gas denitration in two steps, and has the advantages of high ozone utilization ratio, good denitration effect, recyclability of solution, low investment and treatment cost and broad application prospect.

Description

technical field [0001] The invention relates to a two-step oxidation-reduction flue gas denitrification method in the field of flue gas denitrification. Background technique [0002] Acid rain is one of the major environmental problems facing the contemporary world. According to statistics, my country's NO x The total annual discharge exceeds 20 million tons, which is one of the main causes of acid rain. NO x The pollution is serious and endangers the safety of the ecological environment. With the increasing power generation of coal-fired thermal power plants, the regional acid rain pollution in our country will tend to intensify. Coal combustion flue gas emission NO x It is one of the main sources of acid rain, and the denitrification of coal-fired flue gas has become the key to emission control. [0003] So far, coal-fired flue gas NO removal technologies mainly include selective catalytic reduction (SCR), non-selective catalytic reduction (SNCR), SNCR-SCR combined m...

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Problems solved by technology

with TiO 2 The main photocatalytic oxidation denitrification technology does not need to add additional oxidants, and has the advantages of mild reaction conditions, low energy consumption, and less secondary pollution. The efficiency for low-concentration NO can be as high as 90%, but for high-concentration NO removal less efficient

The traditional ozone oxidation method is to oxidize most of the NO in the flue gas into NO 2 After that, it can be absorbed with lye such as ammonia water, the effect is better, but the energy consumption is high, and waste water is generated, which needs to be combined with chemical absorption, which may cause ammonia escape and cause secondary pollution

The plasma denitrification method is to activate and transform NO molecules at room temperature and has attracted much attention, and has achieved fruitful results. However, the current plasma reaction efficiency is low, energy consumption is high, and the selectivity of target products is low. Absorption with ammonia gas will also bring Ammonia leakage and other problems hinder its practical application

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