A pre-sco enhanced flue gas denitrification and mercury removal system for coal-fired power plants

Abstract

The invention relates to a prepositioned SCO intensified flue gas denitration and demercuration technology of a coal-fired power plant. NO and Hg<0> in flue gas are oxidized into NO2 and Hg<2+> in advance and then the NO2 and the Hg<2+> are subjected to an SCR (Selective Catalytic Reduction), so that the aim of efficient denitration and demercuration is realized. A catalyst used by an SCO unit is a Co-Mn-Ti-Ce series catalyst, an active component is one or two of cobalt oxide or manganese oxide, an auxiliary agent component is W and a catalyst carrier is Ce doped TiO2. The Hg<0> can be efficiently oxidized and removed under the condition that previous facilities of the coal-fired power plant do not need to be excessively modified; the oxidization efficiency of the Hg<0> is not influenced in an ammonification process. Meanwhile, dependence on HCl is avoided when O2 and NO are used as an oxidant of the Hg<0>; the given mercury oxidization removing efficiency can be realized without adding additional components in the flue gas; a prepositioned SCO process is used for converting 50 percent of NO at an inlet of an SCR unit into the NO2, so that the reaction efficiency of the SCR process can be remarkably improved. The technology provided by the invention has the advantages that raw materials of the catalyst are easy to obtain, the technological process is easy to implement and industrial application is facilitated.

Description

technical field [0001] The invention belongs to the field of air pollution control, and in particular relates to a pre-SCO enhanced flue gas denitrification and mercury removal technology of a coal-fired power plant. Background technique [0002] With the continuous development of our country's social economy and the gradual improvement of people's living standards, the accompanying environmental pollution problems have become increasingly prominent. my country's coal-based energy structure will not change in the short term, and the environmental pollution problems of flue gas such as nitrogen oxides and sulfur oxides will become increasingly serious. At the same time, in order to meet the construction needs of ecological civilization and scientific development, the country's governance standards for atmospheric environmental pollutants are becoming more and more stringent. The latest revision of the "Emission Standards for Air Pollutants from Thermal Power Plants" was offic...

AI Technical Summary

Problems solved by technology

However, various types of SCR catalysts are sensitive to Hg 0 Oxidation efficiency is not satisfactory in pilot test conditions and field experiments

There are two essential factors that limit its mercury removal efficiency: first, NH 3 to Hg 0 There is a competitive relationship, and a large amount of NH in the SCR process 3 Injection of Hg will be severely suppressed 0 Reacts with the solid-gas interface of the SCR catalyst, resulting in a reduction in oxidation efficiency; 0 The oxidation efficiency of mercury depends heavily on the HCl in the flue gas. However, the Cl content of coal-fired coal in my country is much lower than that of other countries. It is obviously uneconomical to artificially add HCl to the SCR process to improve the mercury oxidation efficiency.

[0004] On the other hand, the denitrification efficiency of the SCR process has no upper limit in theory, but the main consideration in the actual application process is the cost issue

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