CN212204595U

CN212204595U - Pulverized coal partial gasification and denitration system

Info

Publication number: CN212204595U
Application number: CN202020763307.8U
Authority: CN
Inventors: 张向宇; 陆续; 张波; 向小凤; 徐宏杰
Original assignee: China Huaneng Group Co Ltd; Xian Thermal Power Research Institute Co Ltd
Current assignee: China Huaneng Group Co Ltd; Xian Thermal Power Research Institute Co Ltd
Priority date: 2020-05-09
Filing date: 2020-05-09
Publication date: 2020-12-22
Anticipated expiration: 2030-05-09

Abstract

The utility model provides a buggy partial gasification denitration system in coordination, simple structure, reasonable in design reforms transform the convenience, can realize power plant boiler nitrogen oxide ultralow emission under the condition of not spouting ammonia, and technical economy is high. The pulverized coal partial gasification and collaborative denitration system comprises a coal bunker, a coal mill, a boiler, a cyclone separator, a gasification furnace and a filter; a coal outlet of the coal bunker is connected with an inlet of a coal mill, a coal powder outlet of the coal mill is respectively connected with an inlet of a cyclone separator and a burner nozzle arranged in a main combustion area of the boiler, and a coal powder outlet of the coal mill is connected with a primary air pipe; the fine coal powder outlet of the cyclone separator is connected with the burner nozzle, and the coarse coal powder outlet is connected with the gasifier inlet; the coal gas outlet of the gasification furnace is divided into two paths, one path is connected to a flame folding angle area of the boiler through the reburning nozzle, the other path is connected to a tail flue after passing through a filter, and the tail flue connects coal gas to a tail flue at the tail of the air preheater through a spray gun; and a catalyst layer is arranged at the downstream of the spray gun in the tail flue.

Description

Pulverized coal partial gasification and denitration system

Technical Field

The utility model relates to a flue gas denitration technique of thermal power plant specifically is a buggy partial gasification denitration system in coordination.

Background

The emission of nitrogen oxides from coal-fired power plants is one of the main causes of environmental problems such as acid rain, photochemical pollution and the like. In recent years, the emission standard of nitrogen oxides is more and more strict, and the emission concentration of nitrogen oxides is partially required to be not more than 30mg/m³。

Nitrogen oxide emission reduction technologies commonly used in coal-fired power plants include low nitrogen combustion technologies, non-selective catalytic reduction technologies (SNCR), and selective catalytic reduction technologies (SCR). The SNCR and SCR technologies both adopt ammonia as a denitration reducing agent, and in order to ensure higher denitration efficiency, higher ammonia nitrogen molar ratio is adopted in actual operation. However, excessive ammonia injection has great influence on the economy of the denitration technology, and the consumption cost of only ammonia of a 600MW unit per year reaches millions of yuan. In addition, for a thermal power generating unit burning high-sulfur coal, the safety of the unit is seriously influenced by air preheater blockage caused by excessive ammonia injection.

In order to reduce the ammonia consumption of the denitration system, the denitration potential of the low-nitrogen combustion technology needs to be further developed. Low-nitrogen combustion technologies such as air classification and deep air classification are widely adopted, but the problems of boiler combustion efficiency reduction, CO high-temperature corrosion and the like caused by further reduction of the excess air coefficient of a main combustion zone are solved. In recent years, the related art starts to reduce the emission of NOx in the combustion process by fuel classification, for example, a double-hearth coal powder gasification low-nitrogen combustion industrial boiler disclosed in patent CN201610745593 reduces the emission of NOx by using a coal powder gasification combustion technology, re-combusts unburned CO and coal powder by using an auxiliary hearth, and uses a double-hearth structure to ensure that the coal powder has sufficient gasification space and burnout space for combustion. Also, as disclosed in patent CN200910201223, a low NOx combustion method and apparatus using pulverized coal pyrolysis gas reburning is disclosed, in which pulverized coal pyrolysis gas is used as gas reburning fuel, and is fed into a reburning zone of a pulverized coal boiler to efficiently reduce NOx, and carbocoal generated by pulverized coal pyrolysis enters a main burning zone of the pulverized coal boiler under the carrying of primary air to complete combustion. However, the coal powder is completely pyrolyzed or gasified by large pyrolysis or gasification equipment, so that the initial investment is large, and the coal powder is not suitable for the transformation of the conventional coal-fired unit; and the CO is combusted and gasified in the main combustion area, and the CO generated in the main combustion area is easy to form high-temperature corrosion, so that the service life of the equipment is reduced.

SUMMERY OF THE UTILITY MODEL

To the problem that exists among the prior art, the utility model provides a buggy partial gasification denitration system in coordination, simple structure, reasonable in design reforms transform the convenience, can realize power plant boiler nitrogen oxide ultralow emission under the condition of not spouting ammonia, and technical economy is high.

The utility model discloses a realize through following technical scheme:

a pulverized coal partial gasification coordinated denitration system comprises a coal bunker, a coal mill, a boiler, a cyclone separator, a gasification furnace and a filter;

a coal outlet of the coal bunker is connected with an inlet of a coal mill, a coal powder outlet of the coal mill is respectively connected with an inlet of a cyclone separator and a burner nozzle arranged in a main combustion area of the boiler, and a coal powder outlet of the coal mill is connected with a primary air pipe;

the fine coal powder outlet of the cyclone separator is connected with the burner nozzle, and the coarse coal powder outlet is connected with the gasifier inlet;

the gas outlet of the gasification furnace is divided into two paths, one path is connected into a flame folding angle area of the boiler through the reburning nozzle, the other path is connected into a tail flue after passing through a filter, and the tail flue connects the gas into a tail flue at the tail of the air preheater through a spray gun; and a catalyst layer is arranged at the downstream of the spray gun in the tail flue.

Preferably, a primary air adjusting door is arranged on the inlet connecting pipeline of the cyclone separator.

Preferably, the gasification furnace is provided with a water-cooled wall, and the output end of the water-cooled wall is connected with a water feeding port of the boiler.

Preferably, the reburning nozzle is arranged at the lower part of SOFA wind in the boiler.

Preferably, the filter is a ceramic filter.

Preferably, the catalyst layer adopts Cu-Mn/Al₂O₃A catalyst.

Compared with the prior art, the utility model discloses following profitable technological effect has:

the utility model utilizes CO and H generated by coal powder gasification₂The method reduces the nitrogen oxides in the boiler flue gas, realizes the ultralow emission of the nitrogen oxides in the power station boiler under the condition of no ammonia injection, and solves the problems of high ammonia consumption and high ammonia escape in the ammonia injection denitration. The reducing agent CO for the primary high-temperature reduction comes from coal powder, no extra material is consumed, the secondary reduction can be carried out by adopting a non-noble metal catalyst under the low-temperature condition after the primary reduction, and the technical economy is high. The concentration of nitrogen oxides is reduced step by the synergistic action of partial gasification of coal powder, high-temperature reduction of CO and low-temperature catalytic reduction of CO, wherein the concentration of NOx in a high-temperature reduction section is controlled to be 150mg/m³The NOx concentration of the inner and low-temperature reduction sections is controlled to be 50mg/m³Within. The gasification furnace can be used together with the existing coal-fired boiler, thereby completing the low-nitrogen combustion transformation of the existing thermal power generating unit.

The coal powder is subjected to coarse-fine separation in the cyclone separator, and the coarse coal powder enters the gasification furnace, so that the yield of CO in the coal gas can be improved; the fine coal powder enters the boiler for combustion, so that the ignition stability can be improved. The gasified coal gas is mainly sent into a reburning area of the boiler for burning, and the effect of coordinated denitration is generated while the CO is burnt out.

Because the nitrogen oxide that the burning stage produced has showing and has reduced, catalyst volume can reduce, then catalyst and spray gun can arrange in the afterbody flue, and need not external flue, further reduced system complexity, can be used for current coal fired boiler flue gas denitration transformation.

Drawings

FIG. 1 is a schematic structural diagram of a pulverized coal partial gasification cooperative denitration system of the present invention.

In the figure: 1. the coal gasifier comprises a coal bunker, a coal mill 2, a primary air pipe 3, a burner nozzle 4, a boiler 5, a cyclone separator 6, a gasification furnace 7, a coal gas outlet 8, a reburning nozzle 9, a filter 10, a spray gun 11, a catalyst layer 12 and a tail flue 13.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The utility model relates to a buggy partial gasification denitration system in coordination utilizes the CO that buggy gasification produced to come the nitrogen oxide in the efficient reduction boiler flue gas of economy, is different from the ammonia that present thermal power plant's flue gas denitration generally adopted as the reductant completely, has avoided the ammonia consumption that excessive spraying ammonia arouses big and the high problem of ammonia escape.

The denitration system is shown in fig. 1 and comprises a coal bunker 1, a coal mill 2, a boiler 5, a cyclone separator 6, a gasification furnace 7 and a filter 10; a coal outlet of the coal bunker 1 is connected with an inlet of a coal mill 2, a pulverized coal outlet of the coal mill 2 is respectively connected with an inlet of a cyclone separator 6 and a burner nozzle 4 arranged in a main combustion area of a boiler 5, and a pulverized coal outlet of the coal mill 2 is connected with a primary air pipe 3 and is used for conveying pulverized coal through connected primary air; the cyclone separator 6 is used for performing coarse-fine separation on coal powder, the fine coal powder outlet is connected with the burner nozzle 4 to send the fine coal powder into the boiler 5 for burning, the coarse coal powder outlet is connected with the inlet of the gasification furnace 7 to gasify the coarse coal powder in the gasification furnace 7 to generate coal gas; a coal gas outlet 8 of the gasification furnace 7 is divided into two paths, one path is connected to a flame folding angle area of the boiler 5 through a reburning nozzle 9, the other path is connected to a tail flue 13 after ash content is filtered through a filter 10, the tail flue 13 connects coal gas to the tail flue 13 through a spray gun, and a catalyst layer 12 is arranged in the tail flue 13 and is positioned at the downstream of the spray gun.

In the preferred embodiment, the filter 10 is a ceramic filter; the temperature of a tail flue 13 at the tail part of the air preheater is 120-140 ℃; the catalyst layer 12 is made of Cu-Mn/Al₂O₃A catalyst.

The utility model discloses when denitration system uses in coordination.

1) The raw coal in the coal bunker 1 is ground into coal powder by the coal mill 2, and the coal powder is carried into the boiler 5 and the gasification furnace 7 by primary air introduced by the primary air pipe 3, wherein the coal powder entering the gasification furnace 7 accounts for 10-20% and the coal powder entering the boiler 5 accounts for 80-90% in the example. The proportion of the coal powder entering the gasification furnace is reduced when the volatile content of the coal powder is high (such as lignite and bituminous coal); if the volatile component of the pulverized coal is low (such as anthracite), the proportion of the pulverized coal entering the gasification furnace is increased. The amount of the coal dust entering the gasification furnace is controlled by a primary air damper.

2) The coal powder is subjected to coarse-fine separation in the cyclone separator 6, the fine coal powder is sent into the boiler 5 through the burner nozzle 4 for combustion, and the coarse coal powder enters the gasifier 7 for gasification to generate coal gas. The main components of the coal gas are CO and H₂、CO₂And N₂. The gasification furnace 7 adopts an entrained flow bed mode, the gasification agent is air, the heat required by coal powder gasification comes from coke combustion, and the heat does not need to be introduced from a boiler. The gasification furnace is provided with a water-cooled wall which absorbs the heat released by the gasification and combustion of the pulverized coal and heats the boiler feed water, thereby improving the thermal efficiency of the boiler.

3) The coal gas is fed into the boiler 5 for combustion through the reburning nozzle 9, and the reburning nozzle 9 is positioned at the lower part of SOFA wind in the boiler 5. Burning off CO to CO₂And releases heat, and CO and H in the coal gas₂Can reduce nitrogen oxide in the flue gas under the catalytic action of metal oxide in the boiler wall surface and flue gas fly ash to generate N₂And H₂O。

4) Gas in-filterAfter ash is filtered out in the device 10, the ash is sent into a tail flue 13 through a spray gun 11 and reacts with nitrogen oxide in flue gas to generate N under the action of a catalyst layer 12₂And H₂O, thereby reducing boiler NOx emissions. The CO flow in the lance 11 is regulated in accordance with the detected nitrogen oxides, typically in the ppm range.

And 3) the unreacted CO in the step 3) can participate in denitration reaction in the tail flue catalyst layer, so that the escape of CO is reduced. Both the lance 11 and the catalyst layer 12 are arranged in the back pass 13. The catalyst layer 12 is made of Cu-Mn/Al₂O₃The catalyst can achieve 70% of denitration efficiency within the temperature range of 120-140 ℃. Different from the prior art, the catalyst layer 12 is arranged at the tail part of the air preheater, and the temperature of the flue gas ranges from 120 ℃ to 140 ℃.

Claims

1. A pulverized coal partial gasification coordinated denitration system is characterized by comprising a coal bunker (1), a coal mill (2), a boiler (5), a cyclone separator (6), a gasification furnace (7) and a filter (10);

a coal outlet of the coal bunker (1) is connected with an inlet of a coal mill (2), a coal powder outlet of the coal mill (2) is respectively connected with an inlet of a cyclone separator (6) and a burner nozzle (4) arranged in a main combustion area of a boiler (5), and a coal powder outlet of the coal mill (2) is connected with a primary air pipe (3);

a fine coal powder outlet of the cyclone separator (6) is connected with a burner nozzle (4), and a coarse coal powder outlet is connected with an inlet of the gasification furnace (7);

a coal gas outlet (8) of the gasification furnace (7) is divided into two paths, one path is connected to a flame folding angle area of the boiler (5) through a reburning nozzle (9), the other path is connected to a tail flue (13) after passing through a filter (10), and the tail flue (13) connects coal gas to the tail flue (13) at the tail of the air preheater through a spray gun (11); a catalyst layer (12) is arranged at the downstream of the spray gun (11) in the tail flue (13).

2. The pulverized coal partial gasification cooperative denitration system according to claim 1, wherein a primary air damper is arranged on an inlet connecting pipeline of the cyclone separator (6).

3. The pulverized coal partial gasification cooperative denitration system according to claim 1, wherein a water wall is arranged on the gasification furnace (7), and an output end of the water wall is connected with a water supply port of a boiler.

4. The pulverized coal partial gasification cooperative denitration system according to claim 1, wherein the reburning nozzle (9) is disposed at a lower portion of SOFA wind in the boiler (5).

5. The pulverized coal partial gasification cooperative denitration system according to claim 1, wherein the filter (10) is a ceramic filter.

6. The pulverized coal partial gasification cooperative denitration system according to claim 1, wherein the catalyst layer (12) adopts Cu-Mn/Al₂O₃A catalyst.