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Method for realizing SNCR and SCR combined denitration by using coal-fired boiler

A technology for a coal-fired boiler and a realization method, applied in chemical instruments and methods, separation methods, dispersed particle separation, etc., can solve the problems of high operation cost, low denitration rate, complex system, etc., and achieve low operation cost and broad application prospects. , the effect of reducing operating costs

Inactive Publication Date: 2010-07-14
ZHEJIANG UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although SCR technology has high denitrification efficiency, it can change NO into N 2 The conversion rate is over 95%, but its disadvantages are large area, complex system, large initial investment, and high operating cost
Compared with SCR technology, SNCR technology has the advantages of low initial investment, low operating cost, short downtime and installation period, wide application range, and small footprint. However, its biggest defect is that the denitrification rate is lower than that of SCR technology. 30% to 50% NOx removal rate

Method used

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  • Method for realizing SNCR and SCR combined denitration by using coal-fired boiler
  • Method for realizing SNCR and SCR combined denitration by using coal-fired boiler
  • Method for realizing SNCR and SCR combined denitration by using coal-fired boiler

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specific Embodiment 1

[0026] Such as figure 1 What is shown is a method for realizing the joint denitrification of coal-fired boiler SNCR and SCR. Fuel combustion produces 350mg / m in boiler furnace 1 3 The left and right NO flows upward with the flue gas, and a reducing agent spray gun 2 is arranged on the upper part of the furnace. A total of 10 reducing agent spray guns are arranged in two layers on the front wall and side wall, all of which are single-nozzle spray guns. The flue gas temperature in the furnace at the elevation of the spray gun arrangement is 800-950°C. The reducing agent is urea solution with a concentration of 5%-15%, and the molar ratio of the injection amount of the reducing agent to the NO in the flue gas is 1.2:1-1.6:1. The urea solution sprayed into the furnace by the reducing agent spray gun 2 evaporates while mixing with the flue gas, and decomposes into NH 3 and HCNO. NH 3 And part of HNCO reacts with NO to generate N 2 , reducing the NO concentration, part of the...

specific Embodiment 2

[0028] Such as figure 2 What is shown is a method for realizing the joint denitrification of coal-fired boiler SNCR and SCR. Fuel combustion produces 400mg / m in boiler furnace 1 3 The left and right NO flows upward with the flue gas, and the reducing agent spray gun 2 is arranged on the upper part of the furnace. The specific arrangement is as follows: a total of 14 single-nozzle spray guns are arranged on the front wall in two layers; Seven single-nozzle spray guns are arranged along the width direction on the top. The flue gas temperature in the furnace at the elevation of the spray gun arrangement is 700-850°C. The reducing agent is ammonia solution with a concentration of 5-12%, and the molar ratio of the injection amount of the reducing agent to the NO in the flue gas is 1:1-1.5:1. The ammonia solution sprayed into the furnace from the reducing agent spray gun 2 evaporates while mixing with the flue gas. NH 3 Part of it undergoes a reduction reaction with NO to gene...

specific Embodiment 3

[0030] Such as image 3 What is shown is a method for realizing the joint denitrification of coal-fired boiler SNCR and SCR. Fuel combustion produces 350mg / m in boiler furnace 1 3The left and right NO flows upward with the flue gas, and flows through the panel heating surface 7 and the horizontal convection heating surface 6 . Reductant spray guns 2 are arranged in the steering chamber, and the specific arrangement is as follows: two multi-nozzle spray guns are arranged on the left and right side walls at the entrance of the steering chamber; two rows are arranged on the top of the rear steering chamber, and each row is arranged with 8 single-nozzle spray guns along the width direction . The flue gas temperature in the furnace where the spray gun is arranged is 600-800°C. The reducing agent is ammonia solution with a concentration of 12% to 20%, and the molar ratio of the injection amount of the reducing agent to the NO in the flue gas is 1.5:1 to 2:1. The ammonia solution...

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Abstract

The invention discloses a technique for controlling pollutant discharge of coal-fired boilers, and aims to provide a method for realizing SNCR and SCR combined denitration by using a coal-fired boiler. The method comprises the following steps of: arranging a reducing agent spray gun on a flue gas channel of the coal-fired boiler at the flue gas temperature of between 600 and 950 DEG C, and arranging an SCR reactor loaded with an SCR catalyst in a tail gas flue of the boiler; and atomizing a reducing agent by the reducing agent spray gun, then spraying the reducing agent into a gas flue of a furnace chamber, and performing a selective catalytic reduction reaction on the surface of a catalyst when an exhaust gas mixed with NH3 and HNCO flows through the SCR reactor, wherein NO in the flue gas is reduced into N2. The method saves an SCR reducing agent spraying system, improves the utilization ratio of the catalyst in the process of an SNCR reaction, is convenient and easy to implement on a denitration improvement project by the existing furnace, has the denitration efficiency of over 90 percent, is suitable for furnaces burning soft coals and brown coals, is suitable for both medium-sized and large-sized boilers and has extensive application prospects.

Description

technical field [0001] The invention belongs to the pollutant emission control technology of coal-fired boilers, in particular to a coal-fired boiler SNCR and SCR combined high-efficiency denitrification method. Background technique [0002] Nitrogen oxides (including NO, NO 2 and N 2 O, referred to as NOx,) is a gas that can cause serious pollution to the atmospheric environment, and is considered to be one of the main sources of air pollution and acid rain. NOx from burning fossil fuels accounts for a large proportion of all NOx emissions. The biggest feature of my country's energy composition is mainly coal, accounting for more than 70%, which will produce a large amount of NOx emissions. The increasingly stringent environmental regulations require the application of NOx emission reduction technology to NOx emission sources, especially power plant boilers, in order to control the total amount of NOx emissions. Existing nitrogen oxide emission reduction technologies ar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D53/86B01D53/56
Inventor 周俊虎杨卫娟刘建忠王智化周志军黄镇宇程军岑可法
Owner ZHEJIANG UNIV
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