CN107559817B - Rotational flow pulverized coal combustion device and method adopting flue gas recirculation - Google Patents

Rotational flow pulverized coal combustion device and method adopting flue gas recirculation Download PDF

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Publication number
CN107559817B
CN107559817B CN201710860405.6A CN201710860405A CN107559817B CN 107559817 B CN107559817 B CN 107559817B CN 201710860405 A CN201710860405 A CN 201710860405A CN 107559817 B CN107559817 B CN 107559817B
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air pipe
air
flue gas
pulverized coal
flow
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CN201710860405.6A
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CN107559817A (en
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陈智超
严蓉
刘涛
曾令艳
李争起
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哈尔滨工业大学
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Abstract

A rotational flow pulverized coal combustion device and method adopting flue gas recirculation relate to the technical field of industrial pulverized coal boilers. The invention aims to solve the problems of high NOx emission, serious slag bonding and poor burnout of the existing industrial pulverized coal boiler. The burner includes the primary air pipe, the direct current secondary air pipe, the interior secondary air pipe of whirl, the outer secondary air pipe of whirl, recirculation flue gas pipeline and furnace, the primary air pipe, the direct current secondary air pipe, secondary air pipe and the outer secondary air pipe from interior to exterior set gradually in the whirl, the entry end of primary air pipe is connected with the exit end of buggy pipeline, the exit end of recirculation flue gas pipeline is connected with the direct current secondary air pipe respectively, the entry end of secondary air pipe and the outer secondary air pipe of whirl in the whirl, be equipped with interior axial whirl blade in the secondary air pipe in the whirl, be equipped with outer axial whirl blade in the outer secondary air pipe of whirl. The combustion method comprises the steps of mixing flue gas; controlling the flow rate; adjusting the proportion of the flue gas; and (4) igniting. The invention is used for industrial pulverized coal boilers.

Description

Rotational flow pulverized coal combustion device and method adopting flue gas recirculation

Technical Field

The invention relates to the technical field of industrial pulverized coal boilers, in particular to a rotational flow pulverized coal combustion device and method adopting flue gas recirculation.

Background

In China, the coal-fired industrial boiler is a main coal-using device except a power station boiler, the total number of the coal-fired industrial boiler is close to 60 thousands, and the annual consumption of coal is nearly 6.4 hundred million tons. The main problems of the coal-fired industrial boiler in China are as follows: (1) the actual average thermal efficiency is mostly about 65%, while the thermal efficiency of developed countries generally reaches more than 90%; (2) the pollutant emission exceeds the standard and can not reach the national and local emission standards generally, NOx generated by coal-fired industrial boilers is about 200 million tons every year, and the emission is only inferior to that of coal-fired power plant boilers.

In recent years, with the continuous maturity of pulverized coal combustion technology, small horizontal industrial boilers burning pulverized coal have been developed in the field of industrial boilers. The boiler uses pulverized coal as fuel, the pulverized coal burner is arranged at the front part of the hearth, and due to the adoption of the horizontal hearth, the structure is limited, the section and the volume of the hearth of the horizontal boiler are small, and the cyclone flue gas easily sweeps the wall, so that the operation is influenced by slag bonding on the inner wall surface of the boiler. The national environmental protection department explicitly stipulates that the emission of NOx of over 7MW in the emission standard of atmospheric pollutants for boilers (GB13271-2014) issued on 5, 16.2014 does not exceed 400mg/m3 from 10, 1.2015 for coal-fired hot water boilers; the NOx emission of a newly-built coal-fired hot water boiler with the power of more than 7MW is not more than 300mg/m3 from 10 months and 1 day in 2015; for the key area, the NOx emissions must not exceed 200mg/m 3. If emission reduction measures are not taken, increasingly harsh environmental requirements are difficult to meet. At present, some flue gas recirculation pulverized coal burners used on industrial furnaces in China are provided, for example, a patent of invention 'a cyclone pulverized coal burner using flue gas recirculation for industrial kilns' (Chinese patent number ZL201010213627.7, application publication date 11/3/2010, application publication number CN101876433A, hereinafter referred to as 'document one') is provided with annular outer flue gas recirculation passages between a primary air passage and an inner secondary air passage and between the inner secondary air passage and an outer secondary air passage, and the recirculated flue gas is directly sent into the flue gas recirculation passages; the utility model discloses a chinese patent number of patent "high concentration buggy mixes injection apparatus" is ZL201320816332.8, the date of authorized bulletin is 2014 23 months, the number of authorized bulletin is CN203731464U, hereinafter "file two") the interior buggy flow concentration of buggy conveyer pipe is only 1.5 ~ 2kg/kg, the dense buggy flow concentration of combustor exit is only 0.8 ~ 0.9kg/kg air, the combustor overgrate air does not fall into multistage feeding, do not sneak into the flue gas of recirculating in wind, the overgrate air. Practical operation shows that the burner proposed in the document I is easy to cause slag bonding in a hearth, the content of combustible substances in fly ash is increased, and the emission of NOx cannot be effectively controlled; the device proposed by the second document has poor burnout and poor NOx emission reduction effect.

Disclosure of Invention

The invention provides a rotational flow pulverized coal combustion device and method adopting flue gas recirculation, aiming at solving the problems of high NOx emission, serious slag bonding and poor burnout of the existing industrial pulverized coal boiler.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a cyclone pulverized coal combustion device adopting flue gas recirculation comprises a primary air pipe, a direct-current secondary air pipe, a cyclone inner secondary air pipe, a cyclone outer secondary air pipe, a recirculation flue gas pipeline, a hearth and the primary air pipe, the secondary tuber pipe sets gradually from interior to exterior in the whirl, the entry end of primary air pipe is connected with the exit end of buggy pipeline, the exit end of recirculated flue gas pipeline respectively with the direct current secondary tuber pipe, the entry end of secondary tuber pipe and the outer secondary tuber pipe of whirl is connected in the whirl, primary air pipe, the direct current secondary tuber pipe, the exit end of secondary tuber pipe and the outer secondary tuber pipe of whirl is connected with the combustor spout respectively in the whirl, the combustor spout sets up in furnace, combustor spout and furnace inner wall parallel and level, be equipped with interior axial whirl blade in the secondary tuber pipe in the whirl, be equipped with outer axial whirl blade in the outer secondary tuber pipe of whirl.

A swirling pulverized coal combustion method adopting flue gas recirculation comprises the following steps:

the method comprises the following steps: mixing flue gas: the recycling flue gas pipeline respectively sends the flue gas at the tail part of the boiler introduced by the induced draft fan into the direct current secondary air pipe, the rotational flow inner secondary air pipe and the rotational flow outer secondary air pipe, the introduced recycling flue gas and air are respectively mixed in the direct current secondary air pipe, the rotational flow inner secondary air pipe and the rotational flow outer secondary air pipe, so that the volume of the recycling flue gas accounts for 20-30% of the total volume of the flue gas, and the pulverized coal fed by the powder feeder and the air fed by the Roots fan are mixed in the air-powder mixer to form high-concentration pulverized coal airflow which is sent into the primary air pipe;

step two: and (3) flow rate control: high-concentration pulverized coal airflow is sent into a hearth from the center of a burner through a primary air pipe, the flow velocity of the gas in the primary air pipe is 15-18 m/s, the uniformly mixed gas is sent into the hearth through a direct-current secondary air pipe, a rotational flow inner secondary air pipe and a rotational flow outer secondary air pipe, the gas airflow in the direct-current secondary air pipe is sent into the hearth at the speed of 15-18 m/s, the gas airflow in the rotational flow inner secondary air pipe forms rotational jet flow at the speed of 19-21 m/s under the action of an inner axial rotational flow blade and then is sent into the hearth, and the gas airflow in the rotational flow outer secondary air pipe forms rotational jet flow at the speed of 19-21 m/s under the action of an outer axial rotational flow blade and then enters the hearth;

step three: adjusting the flue gas proportion: adjusting the opening degree of each secondary air pipeline valve to adjust the respective air quantity sent into the direct-current secondary air pipe, the rotational flow inner secondary air pipe and the rotational flow outer secondary air pipe, and adjusting the opening degree of each recirculation flue gas pipeline valve to reasonably distribute the proportion of the recirculation flue gas sent into the direct-current secondary air pipe, the rotational flow inner secondary air pipe and the rotational flow outer secondary air pipe;

step four: and (3) igniting: the high-concentration coal dust airflow sprayed out of the primary air pipe and the direct-current secondary air airflow sprayed out of the direct-current secondary air pipe are mixed at a nozzle of the combustor, a backflow area is formed in the center of the airflow by the rotary jet flow sprayed out of the secondary air pipe in the rotational flow and the secondary air pipe outside the rotational flow, and high-temperature flue gas in the entrainment furnace is heated and ignites the coal dust airflow.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention is beneficial to greatly reducing the NOx generation amount

Firstly, in the first document, annular outer flue gas recirculation channels are arranged between a primary air channel and an inner secondary air channel and between the inner secondary air channel and an outer secondary air channel of the combustor, the recirculated flue gas and air enter a hearth in a layered mode at a nozzle of the combustor, the oxygen concentration of air flow of an air layer is higher than that of the recirculated flue gas layer, the air flow is uniformly mixed after being sprayed into the hearth for a certain distance, and when pulverized coal enters the air layer with high oxygen content, the NOx emission is increased. Compared with the 'document I', the device of the invention is not provided with a flue gas recirculation channel independently, the recirculated flue gas and air are mixed in each secondary air pipe, and no gas enters the nozzle of the burner layer by layer, thereby not only saving the mixing process of the flue gas and the air in the furnace, but also ensuring the radial oxygen concentration distribution of the outlet area of the burner to be uniform, ensuring the stable combustion of the pulverized coal, strengthening the reducing atmosphere of the main combustion area, prolonging the retention time of the pulverized coal in the reducing atmosphere and inhibiting the NOx emission of the main combustion area. The oxygen concentration of the gas obtained after the recirculated flue gas and the air are mixed is about 16 percent, and is reduced by about 5 percent compared with the oxygen concentration of the air before mixing, so that the reducing atmosphere of the main combustion zone is strengthened, and the generation amount of NOx in the main combustion zone is effectively reduced.

Secondly, the combustor of the document I concentrates the coal dust in the primary air-dust airflow by arranging a group of conical rings in the primary air channel, but the conical ring coal dust has poor concentration capability and cannot completely concentrate the coal dust airflow into the center of the combustor to be sprayed into a hearth, only a combustion form of 'middle thick and two sides thin' can be formed, concentrated thick and thin coal dust flows can be remixed after passing through a last-stage conical ring, the beneficial effect of reducing NOx by the coal dust thick and thin staged combustion is not fully exerted, in addition, the coal dust airflow in the channel can also form conical surface scouring on the conical ring, the condition that the combustor is replaced because the conical ring is worn by the coal dust in the use process is generated, the operation cost is increased, and the economic benefit of the boiler is reduced. Compared with the 'document I', the device adopts the primary air pipe to convey the high-concentration coal dust airflow, the coal dust is completely concentrated in the center of the burner and sprayed into the hearth, the coal dust concentration of the central reflux area of the outlet of the burner is increased, the coal dust is concentrated in the reducing atmosphere of the central reflux area to be burnt, the retention time of the coal dust in the reducing atmosphere is prolonged, the generation amount of NOx is further reduced, the primary air pipe is adopted to convey the high-concentration coal dust airflow, the abrasion of the coal dust airflow is reduced, and the service life of the burner is prolonged.

And thirdly, the concentration of the high-concentration pulverized coal flow in the pulverized coal conveying pipe of the file II is only 1.5-2 kg of pulverized coal in each kilogram of air, the high-concentration pulverized coal flow is mixed with primary air in the primary air pipe and diluted to be 0.8-0.9 kg of pulverized coal in each kilogram of air, and the concentration of the pulverized coal flow entering the hearth is low. Compared with the 'document two', the concentration of the concentrated coal dust flow in the primary air pipe in the device reaches 2.3-3.1 kg of coal dust in each kilogram of air, the concentrated coal dust flow is directly conveyed into the hearth without contacting with secondary air in the air pipe, the coal dust is completely concentrated in the center of the burner and sprayed into the hearth, the concentration of the coal dust in a central backflow area at the outlet of the burner is increased, the coal dust is concentrated in the reducing atmosphere of the central backflow area to be combusted, and the retention time of the coal dust in the reducing atmosphere is prolonged.

The secondary air of the device in the second document is not provided with multi-stage feeding, and radial air classification is not realized, so that the reduction of NOx emission is not facilitated. Compared with the second document, the device of the invention is provided with a direct-current secondary air pipeline outside the primary air pipe, a rotational flow inner secondary air pipeline and a rotational flow outer secondary air pipeline, and adopts an air radial staged combustion technology, so that the main combustion zone is in a reducing atmosphere, and the NOx emission amount of the main combustion zone can be greatly reduced.

The primary air and the secondary air of the device of the document II are not mixed with the recirculated flue gas, and the oxygen concentration in the primary air and the secondary air is higher, which is not beneficial to reducing the emission of NOx. Compared with the 'document two', in the device, the recirculated flue gas is introduced into the direct-current secondary air pipeline, the rotational-flow inner secondary air pipeline and the rotational-flow outer secondary air pipeline, the recirculated flue gas and the air are uniformly mixed in the air pipes, the mixed recirculated flue gas and the air are sent into the hearth, uniform air-flue gas mixed airflow with low oxygen concentration is formed around the concentrated coal powder, the speed of the combustion reaction is slowed down, the reducing atmosphere of the main combustion zone is enhanced, and the generation amount of NOx in the main combustion zone is effectively reduced.

2. The invention is beneficial to avoiding slagging in the furnace

Compared with the 'document one', the invention does not independently arrange the recirculation flue gas channel, avoids the recirculation flue gas and the air from being sent into the hearth layer by layer, the recirculation flue gas and the air are uniformly mixed in each secondary air pipe, the radial oxygen concentration of the outlet area of the burner is uniformly distributed, the stable combustion of the pulverized coal is ensured, and the slag bonding caused by the non-uniform oxygen concentration distribution and the high combustion temperature of partial area is avoided.

Compared with the second document, the secondary air adopts a radial air staged combustion technology, and the axial swirl blades are arranged in the swirl inner secondary air pipeline and the swirl outer secondary air pipeline, so that the swirl inner secondary air and the swirl outer secondary air rotate to jet, the jet range of gas fed into the furnace in the radial direction of the burner is enlarged, and the vicinity of the furnace wall is in an oxidizing atmosphere, thereby avoiding high-temperature corrosion of the water-cooled wall and slag bonding caused by reduction of ash melting point due to reducing atmosphere.

3. The invention is beneficial to the burnout of the coal dust

The burner of the document one concentrates the pulverized coal in the primary air-pulverized air flow by arranging a group of conical rings in the primary air channel, and the pulverized coal cannot be completely concentrated in the center of the burner and fed into a hearth. Compared with the 'document I', the invention adopts the primary air pipe to completely concentrate the coal powder at the center of the burner and feed the coal powder into the hearth, so that the coal powder sprayed into the furnace is concentrated in the high-temperature central reflux area, the retention time of the coal powder in the high-temperature reflux area is prolonged, and the coal powder is favorably burnt out.

The combustor of the second document is not provided with rotational secondary air outside primary air, so that the secondary air is not used for supplementing combustion, and the rotary air flow is not used for entrainment of high-temperature flue gas for stable combustion, so that the complete combustion of pulverized coal is not favorable. Compared with the second document, the invention arranges the rotational flow inner secondary air pipeline and the rotational flow outer secondary air pipeline outside the direct current secondary air pipeline, and the axial rotational flow blades are additionally arranged in the rotational flow inner secondary air pipeline and the rotational flow outer secondary air pipeline, the center of the ejected rotational air flow forms a backflow area, the central backflow area sucks high-temperature smoke in the furnace to heat the coal dust air flow, and the ignition and the burnout of the coal dust air flow are facilitated.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention, wherein the direction of the hollow arrows indicates the direction of inflow of the secondary air.

Detailed Description

The first embodiment is as follows: the embodiment is described with reference to fig. 1, the cyclone pulverized coal burner using flue gas recirculation according to the embodiment comprises a primary air duct 1, a direct current secondary air duct 2, a cyclone inner secondary air duct 3, a cyclone outer secondary air duct 4, a recirculation flue gas duct 13 and a furnace 16, wherein the primary air duct 1, the direct current secondary air duct 2, the cyclone inner secondary air duct 3 and the cyclone outer secondary air duct 4 are sequentially arranged from inside to outside, an inlet end of the primary air duct 1 is connected with an outlet end of the pulverized coal duct 18, an outlet end of the recirculation flue gas duct 13 is respectively connected with the direct current secondary air duct 2, the cyclone inner secondary air duct 3 and an inlet end of the cyclone outer secondary air duct 4, outlet ends of the primary air duct 1, the direct current secondary air duct 2, the cyclone inner secondary air duct 3 and the cyclone outer secondary air duct 4 are respectively connected with burner nozzles, the burner nozzles are arranged in the furnace 16, and the burner nozzles are flush with an, an inner axial rotational flow blade 6 is arranged in the rotational flow inner secondary air pipe 3, and an outer axial rotational flow blade 5 is arranged in the rotational flow outer secondary air pipe 4.

The second embodiment is as follows: the present embodiment will be described with reference to fig. 1, and in the present embodiment, the primary air duct 1, the straight-flow secondary air duct 2, the swirl inner secondary air duct 3, and the swirl outer secondary air duct 4 are coaxially provided. Technical features not disclosed in the present embodiment are the same as those of the first embodiment.

The third concrete implementation mode: referring to fig. 1, the present embodiment is described, in which the outlet end of the recirculation flue gas duct 13 and the inlet ends of the direct-current secondary air duct 2, the rotational flow inner secondary air duct 3 and the rotational flow outer secondary air duct 4 are respectively connected by a recirculation flue gas branch duct 17, and a recirculation flue gas duct valve 12 is disposed on the recirculation flue gas branch duct 17. The technical features not disclosed in the present embodiment are the same as those of the first or second embodiment.

The fourth concrete implementation mode: referring to fig. 1, the inlet end of the recirculating flue gas duct 13 of the present embodiment is provided with an induced draft fan 14. The technical features not disclosed in the present embodiment are the same as those of the third embodiment.

The fifth concrete implementation mode: referring to fig. 1, the embodiment is described, and secondary air duct valves 11 are disposed at the inlet ends of the direct-flow secondary air duct 2, the swirling inner secondary air duct 3, and the swirling outer secondary air duct 4. The technical features not disclosed in this embodiment are the same as those of the first, second, or fourth embodiment.

The sixth specific implementation mode: the embodiment is described with reference to fig. 1, and the swirling pulverized coal combustion apparatus using flue gas recirculation according to the embodiment further includes a powder feeder 7, an air-powder mixer 8, a roots blower 9, and a pulverized coal bunker 10, wherein the roots blower 9 is disposed at an inlet end of the pulverized coal pipeline 18, the air-powder mixer 8 is disposed in a middle portion of the pulverized coal pipeline 18, the pulverized coal bunker 10 is disposed above the pulverized coal pipeline 18, the powder feeder 7 is disposed at a lower end of the pulverized coal bunker 10, and an outlet end of the powder feeder 7 is connected to the air-powder mixer 8. The technical features not disclosed in the present embodiment are the same as those in the fifth embodiment.

The seventh embodiment: referring to fig. 1, the embodiment is described, and the swirling pulverized coal combustion method using flue gas recirculation according to the embodiment includes the following steps:

the method comprises the following steps: mixing flue gas: the recirculated flue gas pipeline 13 respectively sends the flue gas at the tail part of the boiler introduced by the induced draft fan 14 into the direct current secondary air pipe 2, the rotational flow inner secondary air pipe 3 and the rotational flow outer secondary air pipe 4, the introduced recirculated flue gas and air are respectively mixed in the direct current secondary air pipe 2, the rotational flow inner secondary air pipe 3 and the rotational flow outer secondary air pipe 4, so that the volume of the recirculated flue gas accounts for 20-30% of the total volume of the flue gas, and the pulverized coal fed by the powder feeder 7 and the air fed by the Roots blower 9 are mixed in the air-powder mixer 8 to form high-concentration pulverized coal airflow which is sent into the primary air pipe 1;

step two: and (3) flow rate control: high-concentration pulverized coal airflow is sent into a hearth 16 from the center of a burner through a primary air pipe 1, the flow velocity of the air in the primary air pipe 1 is 15-18 m/s, the uniformly mixed air is sent into the hearth 16 through a direct-current secondary air pipe 2, a rotational-flow inner secondary air pipe 3 and a rotational-flow outer secondary air pipe 4, the air flow in the direct-current secondary air pipe 2 is sent into the hearth 16 at the speed of 15-18 m/s, the air flow in the rotational-flow inner secondary air pipe 3 forms rotational jet flow under the action of an inner axial rotational flow blade 6 at the speed of 19-21 m/s and then is sent into the hearth 16, and the air flow in the rotational-flow outer secondary air pipe 4 forms rotational jet flow at the speed of 19-21 m/s and enters the hearth 16 under the action of an outer axial rotational flow;

step three: adjusting the flue gas proportion: adjusting the opening degree of each secondary air pipeline valve 11 to adjust the respective air quantity sent into the direct-current secondary air pipe 2, the rotational flow inner secondary air pipe 3 and the rotational flow outer secondary air pipe 4, and adjusting the opening degree of each recirculation flue gas pipeline valve 12 to reasonably distribute the proportion of the recirculation flue gas sent into the direct-current secondary air pipe 2, the rotational flow inner secondary air pipe 3 and the rotational flow outer secondary air pipe 4;

step four: and (3) igniting: high-concentration pulverized coal airflow sprayed by the primary air pipe 1 and direct-current secondary air airflow sprayed by the direct-current secondary air pipe 2 are mixed at a burner nozzle, rotary jet flow sprayed by the rotational flow inner secondary air pipe 3 and the rotational flow outer secondary air pipe 4 forms a backflow area at the airflow center, and high-temperature flue gas in the entrainment furnace heats and ignites the pulverized coal airflow.

The specific implementation mode is eight: the embodiment is described with reference to fig. 1, and the mass ratio of the pulverized coal to the air in the high-concentration pulverized coal airflow in the first step of the embodiment is 2.3-3.1: 1. The technical features not disclosed in this embodiment are the same as those in the seventh embodiment. Namely, the content of the coal dust in each kilogram of air in the high-concentration coal dust airflow is 2.3-3.1 kg.

Claims (6)

1. The utility model provides an adopt flue gas recirculation's whirl buggy burner which characterized in that: the cyclone pulverized coal combustion device adopting flue gas recirculation comprises a primary air pipe (1), a direct-current secondary air pipe (2), a cyclone inner secondary air pipe (3), a cyclone outer secondary air pipe (4), a recirculation flue gas pipeline (13), a hearth (16), a powder feeder (7), an air-powder mixer (8), a Roots blower (9) and a pulverized coal bin (10), wherein the primary air pipe (1), the direct-current secondary air pipe (2), the cyclone inner secondary air pipe (3) and the cyclone outer secondary air pipe (4) are sequentially arranged from inside to outside, the inlet end of the primary air pipe (1) is connected with the outlet end of the pulverized coal pipeline (18), the outlet end of the recirculation flue gas pipeline (13) is respectively connected with the inlet ends of the direct-current secondary air pipe (2), the cyclone inner secondary air pipe (3) and the cyclone outer secondary air pipe (4), the primary air pipe (1), the direct-current secondary air pipe (2), The outlet ends of the cyclone inner secondary air pipe (3) and the cyclone outer secondary air pipe (4) are respectively connected with a burner nozzle, the burner nozzle is arranged in a hearth (16) and is parallel and level with the inner wall (15) of the hearth, an inner axial cyclone blade (6) is arranged in the cyclone inner secondary air pipe (3), an outer axial cyclone blade (5) is arranged in the cyclone outer secondary air pipe (4), a Roots blower (9) is arranged at the inlet end of a pulverized coal pipeline (18), an air-powder mixer (8) is arranged in the middle of the pulverized coal pipeline (18), a pulverized coal bunker (10) is arranged above the pulverized coal pipeline (18), a powder feeder (7) is arranged at the lower end of the pulverized coal bunker (10), and the outlet end of the powder feeder (7) is connected with the air-powder mixer (8), the primary air pipe (1), the direct-current secondary air pipe (2), the rotational flow inner secondary air pipe (3) and the rotational flow outer secondary air pipe (4) are coaxially arranged.
2. The swirling pulverized coal combustion device adopting flue gas recirculation according to claim 1, characterized in that: the outlet end of the recirculation flue gas pipeline (13) is connected with the inlet ends of the direct-current secondary air pipe (2), the rotational flow inner secondary air pipe (3) and the rotational flow outer secondary air pipe (4) through a recirculation flue gas branch pipeline (17), and a recirculation flue gas pipeline valve (12) is arranged on the recirculation flue gas branch pipeline (17).
3. The swirling pulverized coal combustion device adopting flue gas recirculation according to claim 2, characterized in that: and an induced draft fan (14) is arranged at the inlet end of the recirculation flue gas pipeline (13).
4. The swirling pulverized coal combustion device using flue gas recirculation according to claim 1 or 3, characterized in that: and secondary air pipeline valves (11) are arranged at the inlet ends of the direct-current secondary air pipe (2), the rotational flow inner secondary air pipe (3) and the rotational flow outer secondary air pipe (4).
5. A rotational flow pulverized coal combustion method adopting flue gas recirculation is characterized in that: the method comprises the following steps:
the method comprises the following steps: mixing flue gas: the boiler tail smoke introduced by a draught fan (14) is respectively sent into a direct current secondary air pipe (2), a rotational flow inner secondary air pipe (3) and a rotational flow outer secondary air pipe (4) by a recirculation smoke pipeline (13), the introduced recirculation smoke and air are respectively mixed in the direct current secondary air pipe (2), the rotational flow inner secondary air pipe (3) and the rotational flow outer secondary air pipe (4), so that the volume of the recirculation smoke accounts for 20-30% of the total volume of the smoke, and pulverized coal fed by a powder feeder (7) and air fed by a Roots fan (9) are mixed in an air-powder mixer (8) to form high-concentration pulverized coal airflow and are sent into a primary air pipe (1);
step two: and (3) flow rate control: high-concentration pulverized coal airflow is sent into a hearth (16) from the center of a burner through a primary air pipe (1), the flow velocity of the air in the primary air pipe (1) is 15-18 m/s, the uniformly mixed air is sent into the hearth (16) through a direct-current secondary air pipe (2), a rotational-flow inner secondary air pipe (3) and a rotational-flow outer secondary air pipe (4), the air flow in the direct-current secondary air pipe (2) is sent into the hearth (16) at the speed of 15-18 m/s, the air flow in the rotational-flow inner secondary air pipe (3) forms rotary jet flow under the action of an inner axial rotational flow blade (6) and then is sent into the hearth (16), and the air flow in the rotational-flow outer secondary air pipe (4) forms rotary jet flow under the speed of 19-21 m/s and the action of an outer axial rotational flow blade (5) and then enters the hearth (16);
step three: adjusting the flue gas proportion: adjusting the opening degree of each secondary air pipeline valve (11) to adjust the respective air quantity sent into the direct current secondary air pipe (2), the rotational flow inner secondary air pipe (3) and the rotational flow outer secondary air pipe (4), and adjusting the opening degree of each recirculation flue gas pipeline valve (12) to reasonably distribute the proportion of the recirculation flue gas sent into the direct current secondary air pipe (2), the rotational flow inner secondary air pipe (3) and the rotational flow outer secondary air pipe (4);
step four: and (3) igniting: high-concentration pulverized coal airflow sprayed by the primary air pipe (1) and direct-current secondary air airflow sprayed by the direct-current secondary air pipe (2) are mixed at a burner nozzle, rotary jet flow sprayed by the rotational flow inner secondary air pipe (3) and the rotational flow outer secondary air pipe (4) form a backflow area at the airflow center, and high-temperature flue gas in the entrainment furnace is heated and ignites the pulverized coal airflow.
6. The swirling pulverized coal combustion method using flue gas recirculation according to claim 5, characterized in that: in the first step, the mass ratio of the coal powder to the air in the high-concentration coal powder airflow is 2.3-3.1: 1.
CN201710860405.6A 2017-09-21 2017-09-21 Rotational flow pulverized coal combustion device and method adopting flue gas recirculation CN107559817B (en)

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CN109654485A (en) * 2018-12-18 2019-04-19 哈尔滨工业大学 A kind of swirling pulverized coal combustion device using flue gas recirculation and precombustion chamber
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