CN212017384U

CN212017384U - Coal-fired flue gas hierarchical denitration control SO2/SO3System for conversion rate

Info

Publication number: CN212017384U
Application number: CN201921923498.3U
Authority: CN
Inventors: 张杨; 洪志刚; 江建平; 陈艺秋; 王艳鹏; 徐克涛; 杨用龙; 朱跃
Original assignee: Huadian Electric Power Research Institute Co Ltd
Current assignee: Huadian Electric Power Research Institute Co Ltd
Priority date: 2019-11-08
Filing date: 2019-11-08
Publication date: 2020-11-27
Anticipated expiration: 2029-11-08

Abstract

The utility model discloses a hierarchical denitration control SO of coal-fired flue gas₂/SO₃A system for conversion rate belongs to the field of industrial waste gas purification, environmental protection and energy. The utility model discloses a boiler, the exhanst gas outlet intercommunication of boiler has the economizer, the export of economizer communicates simultaneously has the flue main and assists the flue, set gradually in the flue main and spout ammonia grid, SCR denitration reactor and air preheater, from the top down is provided with upper catalyst and lower floor's catalyst in the SCR denitration reactor, it communicates to SCR denitration catalyst to assist the flueThe middle part of the reactor and the outlet of the auxiliary flue are connected between the upper layer catalyst and the lower layer catalyst. Through the system, can be under the prerequisite that does not influence denitration performance effectively control denitration catalyst's SO_2/SO₃The conversion rate has the advantages of simple system, flexible operation and maintenance and the like, and has wide application prospect.

Description

Coal-fired flue gas hierarchical denitration control SO2/SO3System for conversion rate

Technical Field

The utility model belongs to industrial waste gas purifies environmental protection and energy field, in particular to hierarchical denitration control SO of coal-fired flue gas₂/SO₃System for conversion.

Background

The energy structure mainly based on coal in China can not be changed for a long time, so that the control of the emission of NOx in the flue gas of coal combustion is an important work for controlling atmospheric pollution in China. By NH₃The NOx Selective Catalytic Reduction (SCR) technology which is a reducing agent is the most widely applied and effective coal-fired flue gas denitration technology in recent years. However, the SCR denitration catalyst which is currently commercially applied has catalytic SO while catalyzing denitration₂Conversion to SO₃Of SO₃Can cause a series of problems of subsequent equipment corrosion, emission pollution and the like, and becomes a difficult problem of the current coal-fired flue gas pollutant treatment. Therefore, based on the SCR denitration technology widely applied at present, how to effectively control SO while realizing high-efficiency denitration₂/SO₃The conversion rate becomes an important subject in the field of denitration of the current coal-fired flue gas.

To the above problem, the utility model discloses team research finds that under the condition that ammonia nitrogen ratio surpassed 1, the SO of denitration catalyst₂Conversion catalysis will be effectively inhibited, based on this the utility model provides a hierarchical denitration control SO of coal-fired flue gas₂/SO₃Systems for conversion, i.e.The coal-fired flue gas enters the SCR denitration reactor for denitration in a grading manner, SO that the ammonia nitrogen ratio in the upper-level denitration process is excessive, and the SO of the total denitration catalyst is effectively inhibited₂/SO₃And (4) conversion rate.

The related patents of the present invention, for example, the Chinese patent application with publication number CN 106178950A and publication number 2016, 12 and 7 months in 2016 (one kind of low SO)₂/SO₃SCR denitration system for conversion rate is characterized in that a heat exchanger is arranged between a first layer catalyst and a second layer catalyst in an SCR denitration reactor to reduce the temperature of flue gas, SO that SO of the catalysts is controlled₂/SO₃And (4) conversion rate. However, the temperature is lowered, and the denitration reaction capability is also affected.

The related patents of the utility model, for example, the Chinese patent application with publication number CN 109482181A and publication date of 2019, 3 and 19 months₂/SO₃A denitration catalyst for conversion rate and a preparation method thereof are characterized in that the conversion rate of sulfur dioxide to sulfur trioxide is effectively reduced by changing the formula of the catalyst, controlling the content of vanadium pentoxide and adding ruthenium trichloride on the premise of ensuring the denitration efficiency of the catalyst. But this will result in an increase in the production cost of the catalyst.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome the above-mentioned not enough that exists among the prior art, and provide a hierarchical denitration control SO of coal-fired flue gas₂/SO₃System for conversion.

The utility model provides a technical scheme that above-mentioned problem adopted is: coal-fired flue gas hierarchical denitration control SO₂/SO₃The system for conversion rate comprises a boiler and is characterized in that a flue gas outlet of the boiler is communicated with an economizer, an outlet of the economizer is simultaneously communicated with a main flue and an auxiliary flue, an ammonia injection grid, an SCR denitration reactor and an air preheater are sequentially arranged in the main flue, an upper-layer catalyst and a lower-layer catalyst are arranged in the SCR denitration reactor from top to bottom, the auxiliary flue is communicated to the middle of the SCR denitration reactor, and an outlet of the auxiliary flue is connected between the upper-layer catalyst and the lower-layer catalyst.

Further, the outlet of the auxiliary flue is connected with a nozzle, and the nozzle is vertically arranged upwards.

Furthermore, the upper layer catalyst is arranged with 2-3 layers, the lower layer catalyst is arranged with 1 layer, and the type, specification and volume of each layer catalyst are generally the same.

Further, when the catalyst is replaced when its life is expired, whether the old catalyst to be replaced is located in the upper layer or the lower layer, it is ensured that the new catalyst to be replaced is installed in the lower layer, and if the old catalyst to be replaced is located in the upper layer, the old catalyst in the lower layer can be moved to the upper layer for further use.

Compared with the prior art, the utility model, have following advantage and effect: through the system, the SO of the denitration catalyst can be effectively controlled on the premise of not influencing the denitration performance₂/SO₃The conversion rate has the advantages of simple system, flexible operation and maintenance and the like, and has wide application prospect.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

In the figure: the system comprises a boiler 1, an economizer 2, a baffle door 3, an ammonia injection grid 4, an upper catalyst 5, a lower catalyst 6, an air preheater 7, a main flue 8, an auxiliary flue 9, a nozzle 10 and an SCR denitration reactor 11.

Detailed Description

The present invention will be described in further detail by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not intended to limit the present invention.

Referring to fig. 1, in the embodiment, the coal-fired flue gas is subjected to graded denitration to control SO₂/SO₃The system for conversion rate comprises a boiler 1 and is characterized in that a flue gas outlet of the boiler 1 is communicated with an economizer 2, an outlet of the economizer 2 is simultaneously communicated with a main flue 8 and an auxiliary flue 9, an ammonia injection grid 4, an SCR denitration reactor 11 and an air preheater 7 are sequentially arranged in the main flue 8, an upper-layer catalyst 5 and a lower-layer catalyst 6 are arranged in the SCR denitration reactor 11 from top to bottom, the auxiliary flue 9 is communicated to the middle of the SCR denitration reactor 11, and an outlet of the auxiliary flue 9 is connected with the upper-layer catalyst 5 and the lower-layer catalyst 5Between the

layer catalyst

6, 2 layers are arranged on the upper layer catalyst 5, 1 layer is arranged on the lower layer catalyst 6, the specification and the volume of each layer of catalyst are the same, the outlet of the auxiliary flue 9 is connected with a nozzle 10, and the nozzle 10 is vertically arranged upwards.

The working method comprises the following steps: after the flue gas comes out of the boiler 1, the flue gas firstly enters the economizer 2 and then is divided into two parts, one part of the flue gas enters the main flue 8 and is mixed with ammonia gas sprayed by the ammonia spraying grid 4, then enters the SCR denitration reactor 11 to carry out denitration reaction under the action of the upper catalyst 5, the other part of the flue gas enters the auxiliary flue 9 and enters the SCR denitration reactor 11 from the middle part thereof, is mixed with the flue gas passing through the upper catalyst 5, then enters the lower catalyst 6 to carry out denitration reaction, then passes through the air preheater 7, and finally enters the chimney to be discharged after passing through the tail flue gas treatment device. The ratio of the flue gas quantity Q1 entering the auxiliary flue 9 to the total flue gas quantity Q is controlled within 0.3. The flue gas entering the auxiliary flue 9 enters the SCR denitration reactor 11 in a grid mode, and the nozzles 10 are vertically arranged upwards, so that the mixing of the flue gas and the flue gas of the main flue 8 is enhanced. A baffle door 3 is arranged in the auxiliary flue 9, and the flue gas quantity Q1 entering the auxiliary flue 9 can be controlled by adjusting the opening degree of the baffle door 3 in actual operation.

Through the system, the SO of the denitration catalyst can be effectively controlled on the premise of not influencing the denitration performance₂/SO₃The conversion rate has the advantages of simple system, flexible operation and maintenance and the like, and has wide application prospect.

Those not described in detail in this specification are well within the skill of the art.

Although the present invention has been described with reference to the above embodiments, it should not be construed as being limited to the scope of the present invention, and any modifications and alterations made by those skilled in the art without departing from the spirit and scope of the present invention should fall within the scope of the present invention.

Claims

1. Coal-fired flue gas hierarchical denitration control SO₂/SO₃The system for conversion rate comprises a boiler (1) and is characterized in that a smoke outlet of the boiler (1) is communicatedThe device is characterized by comprising an economizer (2), wherein the outlet of the economizer (2) is simultaneously communicated with a main flue (8) and an auxiliary flue (9), an ammonia injection grid (4), an SCR denitration reactor (11) and an air preheater (7) are sequentially arranged in the main flue (8), an upper-layer catalyst (5) and a lower-layer catalyst (6) are arranged in the SCR denitration reactor (11) from top to bottom, the auxiliary flue (9) is communicated to the middle of the SCR denitration reactor (11), and the outlet of the auxiliary flue (9) is connected between the upper-layer catalyst (5) and the lower-layer catalyst (6).

2. The coal-fired flue gas staged denitration control SO of claim 1₂/SO₃The system for conversion rate is characterized in that a baffle door (3) is arranged in the auxiliary flue (9).

3. The coal-fired flue gas staged denitration control SO of claim 1₂/SO₃The system for conversion rate is characterized in that the outlet of the auxiliary flue (9) is connected with a nozzle (10), and the nozzle (10) is vertically and upwards arranged.

4. The coal-fired flue gas staged denitration control SO of claim 1₂/SO₃The system for conversion rate is characterized in that 2-3 layers of the upper layer catalyst (5) are arranged, 1 layer of the lower layer catalyst (6) is arranged, and the type, specification and volume of each layer of catalyst are the same.