CN102721040A - Device for NOx reduction and grate firing by stokehold screening, gasifying and reburning - Google Patents

Abstract

A device for NOx reducing and grate firing by stokehold screening, gasifying and reburning belongs to the technical field of environment-friendly equipment and aims to realize the low NOx discharge amount and high efficiency burning of a grate firing industrial boiler. A stokehold screening and sorting device comprises a large-particle coal hopper, a medium-particle coal hopper and a small-particle coal hopper, wherein the medium-particle coal hopper is arranged between the large-particle coal hopper and the small-particle coal hopper, material inlet cavities of the large-particle coal hopper, the medium-particle coal hopper and the small-particle coal hopper are communicated with each other, a large-mesh screen is arranged in the large-particle coal hopper, a medium-mesh screen is arranged in the medium-particle coal hopper, the small-mesh screen is arranged in the small-particle coal hopper, a fire coal conveyer device is communicated with the small-particle coal hopper, the small-particle coal hopper and the medium-particle coal hopper are communicated with a spiral material conveyer which is communicated with a boiler coal hopper, the boiler coal hopper is communicated with a boiler, the large-particle coal hopper is communicated with a fixed bed gasification furnace, a gasifying gas outlet of the fixed bed gasification furnace is communicated with a gasifying gas spray nozzle by a fan and a gasifying gas pipeline, combustion air pipeline is communicated with the gasifying gas spray nozzle which is arranged in the boiler. The device is matched with the boiler for use.

Description

A sorting, gasification and reburning equipment in front of the furnace to reduce NOx layer combustion

technical field

The invention relates to equipment for reducing NOx layer combustion, which belongs to the technical field of environmental protection equipment.

Background technique

There are about 546,000 coal-fired industrial boilers in service in my country, accounting for 85% of the total number of industrial boilers currently in service, and increasing at a rate of about 1.5% every year. The annual coal consumption of coal-fired industrial boilers is 500-600 million tons, accounting for about 18% of the country's total annual coal consumption. The annual total energy consumption and pollution discharge of industrial boilers both rank second in the national industrial industry.

In the research on the emission reduction of industrial boiler pollutants, the research on SO ₂ and soot was carried out relatively early, and many research results have been obtained, and they have been applied industrially. Due to the low-temperature combustion of industrial boilers, the amount of NOx generated is relatively low (400-700mg/Nm3). Therefore, the NOx emission reduction work of industrial boilers has not received sufficient attention (the NOx emission of industrial boilers is less than that of power station pulverized coal boilers, so the current attention is not enough and it is not applicable to reduce NOx emissions of existing power station pulverized coal boilers technology). In recent years, my country's environmental protection requirements have been increasing year by year, making the NOx emission problem of industrial boilers more and more prominent. Especially NOx in the urban air environment has an effect on PM2.5 (PM2.5 refers to particulate matter with a diameter less than or equal to 2.5 microns in the atmosphere, also known as particulate matter that can enter the lungs. Although PM2.5 is only a small amount in the earth's atmospheric components components, but it has an important impact on air quality and visibility. PM2.5 has a small particle size, is rich in a large amount of toxic and harmful substances, and has a long residence time in the atmosphere and a long transportation distance, so it is harmful to human health and the atmosphere. The contribution rate of secondary sources that have a greater impact on environmental quality) has gradually drawn attention. Therefore, it is very urgent to develop an economical layer-fired boiler low-NOx combustion technology that is coordinated with the combustion process.

Contents of the invention

The purpose of the present invention is to provide a kind of equipment for reducing NOx layer combustion by sorting, gasification and reburning in front of the furnace, which can realize low NOx emission and high-efficiency combustion of the layer-fired industrial boiler synergistically.

The technical scheme that the present invention takes for solving the above problems is:

A pre-furnace sorting, gasification and recombustion equipment for reducing NOx layer combustion, the equipment includes a boiler coal hopper, a fan, and a coal-fired conveying device, and the equipment also includes a pre-furnace screening and sorting device, a transition pipe, and a gasification gas pipeline , Combustion air pipeline, fixed bed gasifier, screw material conveyor and gasification gas nozzle;

The screening and sorting device in front of the furnace includes a large-grain coal hopper, a medium-grain coal hopper and a small-grain coal hopper, the medium-grain coal hopper is arranged between the large-grain coal hopper and the small-grain coal hopper, the large-grain coal hopper, the medium-grain coal hopper The feeding chambers of the coal hopper and the small particle coal hopper are connected. The large particle coal hopper is equipped with a large mesh screen, the medium particle coal hopper is equipped with a medium mesh mesh, and the small particle coal Mesh sieves, the large sieves, medium sieves and small sieves are all arranged in the same inclined plane, and the end of the inclined plane adjacent to the boiler coal hopper is higher than the inclined plane and away from the One end of the coal hopper of the boiler, the front end of the coal-fired conveying device communicates with the feeding chamber of the screening and sorting device in front of the furnace through a transition pipe, and the discharge port of the small particle coal hopper and the discharge port of the medium particle coal hopper are all connected to the The feed port of the screw conveyor is connected, one end of the discharge port of the screw conveyor is higher than the feed port of the screw conveyor, the discharge port of the screw conveyor is connected with the coal hopper of the boiler, and the discharge port of the boiler coal hopper The coal port is connected to the coal inlet of the boiler, the discharge port of the large particle coal hopper is connected to the fixed bed gasifier, and the gasification gas outlet of the fixed bed gasifier is connected to the gasification gas nozzle through the fan and the gasification gas pipeline. The combustion-supporting air pipeline communicates with the gasification gas nozzle, and the gasification gas nozzle is arranged in the furnace of the boiler.

The beneficial effects of the present invention are as follows: 1. The furnace coal is subjected to particle size classification by adopting a screening and sorting device in front of the furnace. According to "Technical Conditions for Coal Used in Chain Boilers" GB/T18342-2009, for lump coal: it is divided into three categories: <6mm, 6-15mm, and 15-25m; for mixed coal: it is divided into <6mm, 6-20mm, 20-50m Three categories. It is defined in turn as small, medium and large particle sizes. The medium and small particles are fed into the original boiler coal hopper of the boiler, and then fed into the furnace for combustion by the boiler coal hopper. Send large-particle coal into the fixed-bed gasifier for gasification, and the particle size span of the coal fed into the furnace will be reduced, which will help improve the stability and uniformity of combustion in the boiler, thereby improving combustion efficiency and reducing incomplete combustion of solids loss. Large particle coal is fed into the fixed bed gasifier, which is beneficial to reduce the flow resistance in the gasifier and reduce the possibility of coking. 2. The main components of the gasification gas are CO, CH ₄ , H _{2 ,} etc., and the gasification gas is sent to a suitable position above the boiler furnace for combustion, which can realize the partial reduction of NO produced by the combustion of the lower layer. The reaction mechanism is as follows:

CO+NO→N ₂ +CO ₂

CH ₄ +NO→N ₂ +CO ₂ +H ₂ O

H ₂ +NO→N ₂ +H ₂ O

3. The combustion of gasification gas can increase the temperature level of the furnace space and increase the heat absorption of the heating surface of the furnace. According to the different ratios of gasification gas feeding, it can increase the heating (evaporation capacity) of the boiler by 3-10%. By arranging suitable burn-off air (combustion-supporting air), the incomplete combustion loss of gas can be effectively reduced. 4. The equipment of the present invention can realize low NOx emission of the layer fired boiler, and the present invention is applicable to various types of layered combustion devices and equipment. Through the operation of this equipment, NOx emissions can be reduced by more than 30-50%, the combustion efficiency of the boiler can be increased by 0.5-1%, and the heating (evaporation) capacity of the boiler can be increased by 3-10%.

Description of drawings

Figure 1 is a schematic front view of the overall structure of the present invention.

Detailed ways

Specific embodiment 1: In conjunction with Fig. 1, a kind of equipment for furnace separation, gasification and reburning to reduce NOx layer combustion in this embodiment, the equipment includes a boiler coal hopper 1, a fan 2 and a coal-fired conveying device 4, the equipment It also includes furnace front screening and sorting device 5, transition pipe 6, gasification gas pipeline 7, combustion air pipeline 8, fixed bed gasifier 9, screw material conveyor 10 and gasification gas nozzle 11;

The screening and sorting device 5 in front of the furnace includes a large particle coal hopper 5-1, a medium particle coal hopper 5-2 and a small particle coal hopper 5-3, and the medium particle coal hopper 5-2 is arranged on the large particle coal hopper 5- 1 and the small particle coal hopper 5-3, the feeding chambers of the large particle coal hopper 5-1, the medium particle coal hopper 5-2 and the small particle coal hopper 5-3 are connected and arranged, and the large particle coal hopper 5-3 1 is equipped with a large mesh sieve 5-1-1, a medium particle coal sieve 5-2 is equipped with a medium mesh sieve 5-2-1, and a small particle coal hopper 5-3 is equipped with a small mesh sieve 5-3-1, the large sieve sieve 5-1-1, the middle sieve 5-2-1 and the small sieve 5-3-1 are all arranged in the same inclined plane, so The end of the inclined surface adjacent to the boiler coal hopper 1 is higher than the end of the inclined surface away from the boiler coal hopper 1, and the front end of the coal-fired conveying device 4 passes through the transition pipe 6 and the feed of the furnace screening and sorting device 5 The cavity is connected, and the discharge port of the small particle coal hopper 5-3 and the discharge port of the medium particle coal hopper 5-2 are connected with the feed port of the screw material conveyor 10, and one end of the discharge port of the screw material conveyor 10 is high At one end of the feed port of the screw material conveyor 10, the discharge port of the screw material conveyor 10 communicates with the boiler coal hopper 1, the coal outlet of the boiler coal hopper 1 communicates with the coal inlet of the boiler 3, and the large particle coal hopper 5 -1 is connected to the fixed bed gasification furnace 9, the gasification gas outlet of the fixed bed gasification furnace 9 is connected to the gasification gas nozzle 11 through the fan 2 and the gasification gas pipeline 7, and the combustion air pipeline 8 is connected to the gasification gas nozzle 11. The gasification gas nozzle 11 is connected, and the gasification gas nozzle 11 is arranged in the furnace of the boiler 3 . The screw material conveyor 10 used in this embodiment is the prior art.

Specific embodiment two: In conjunction with Fig. 1 description, the aperture of the small mesh screen 5-3-1 of the present embodiment<6mm, the aperture of the medium mesh screen 5-2-1 is 6-15mm, and the large mesh screen The hole diameter of sheet 5-1-1 is 15-25mm. Suitable for screening lump coal. Others are the same as in the first embodiment.

Specific embodiment three: In conjunction with Fig. 1 description, the aperture of the small mesh screen 5-3-1 of the present embodiment<6mm, the aperture of the medium mesh screen 5-2-1 is 6-20mm, and the large mesh screen The hole diameter of sheet 5-1-1 is 20-50mm. Suitable for screening mixed coal. Others are the same as in the first embodiment.

Embodiment 4: In conjunction with FIG. 1 , the coal-fired conveying device 4 in this embodiment is a horizontal conveyor belt conveying device. for existing technology. Others are the same as the specific embodiment 1, 2 or 3.

The process is as follows: the coal from the public coal delivery system is transported through the coal delivery device 4, and enters into the screening and sorting device 5 in front of the furnace through the transition pipe 6, and the coal is divided into three types: large, medium and small. particle size. The coal with medium and small particle sizes is sent back to the coal hopper 1 of the boiler through the screw material conveyor 10 for combustion; the large particle size coal is sent to the fixed-bed gasifier 9 for gasification. The gasification gas is sent into the furnace space of the boiler 3 through the fan 2 and the gasification gas pipeline 7 for combustion, and the combustion-supporting air is sent into the furnace of the boiler 3 through the combustion-supporting air pipeline 8 for combustion.

Claims (4)

1. A sorting, gasification and reburning equipment for reducing NOx layer combustion in front of the furnace, the equipment includes a boiler coal hopper (1), a fan (2) and a coal-fired conveying device (4), characterized in that: the equipment also includes Furnace screening and sorting device (5), transition pipe (6), gasification gas pipeline (7), combustion air pipeline (8), fixed bed gasifier (9), screw material conveyor (10) and Gasification gas nozzle (11); The screening and sorting device (5) in front of the furnace includes a large particle coal hopper (5-1), a medium particle coal hopper (5-2) and a small particle coal hopper (5-3), a medium particle coal hopper (5- 2) Set between the large particle coal hopper (5-1) and the small particle coal hopper (5-3), the large particle coal hopper (5-1), the medium particle coal hopper (5-2) and the small particle coal hopper (5-3) The feeding chambers of the three are connected. The large-grained coal hopper (5-1) is equipped with a large mesh screen (5-1-1), and the medium-grained coal hopper (5-2) is equipped with a There is a medium sieve sieve (5-2-1), a small sieve sieve (5-3-1) is installed in the small particle coal hopper (5-3), and the large sieve sieve (5-1 -1), the medium sieve mesh (5-2-1) and the small sieve mesh (5-3-1) are all set in the same inclined plane, which is adjacent to the boiler coal hopper (1) One end of the inclined surface is higher than the end of the boiler coal hopper (1), and the front end of the coal-fired conveying device (4) communicates with the feeding chamber of the furnace front screening and sorting device (5) through the transition pipe (6) , the discharge port of the small particle coal hopper (5-3) and the discharge port of the medium particle coal hopper (5-2) are connected with the feed port of the screw material conveyor (10), and the screw material conveyor (10) One end of the discharge port is higher than the feed port end of the screw material conveyor (10), the discharge port of the screw material conveyor (10) is connected with the boiler coal hopper (1), and the coal discharge port of the boiler coal hopper (1) It is connected to the coal inlet of the boiler (3), the discharge port of the large particle coal hopper (5-1) is connected to the fixed bed gasifier (9), and the gasification gas outlet of the fixed bed gasifier (9) passes through the fan (2) and the gasification gas pipeline (7) communicate with the gasification gas nozzle (11), the combustion air pipeline (8) communicates with the gasification gas nozzle (11), and the gasification gas nozzle (11) is set In the furnace of the boiler (3). 2. According to claim 1, a furnace sorting, gasification and reburning equipment for reducing NOx layer combustion is characterized in that: the aperture of the small mesh screen (5-3-1) is <6mm, and the middle mesh screen (5-3-1) 5-2-1) has a pore size of 6-15mm, and the large sieve (5-1-1) has a pore size of 15-25mm. 3. According to claim 1, a sorting, gasification and reburning equipment for reducing NOx layer combustion in front of the furnace is characterized in that: the aperture of the small sieve (5-3-1) is <6mm, and the medium sieve (5-3-1) 5-2-1) has an aperture of 6-20mm, and the large mesh screen (5-1-1) has an aperture of 20-50mm. 4. According to claim 1, 2 or 3, the furnace sorting gasification reburning reduction NOx layer combustion equipment is characterized in that: the coal-fired conveying device (4) is a horizontal conveyor belt conveying device.

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