CN111947135B - Combustion method of W flame boiler capable of realizing self-stable combustion of ultralow-load concentrated pulverized coal airflow - Google Patents
Combustion method of W flame boiler capable of realizing self-stable combustion of ultralow-load concentrated pulverized coal airflow Download PDFInfo
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- CN111947135B CN111947135B CN202010877329.1A CN202010877329A CN111947135B CN 111947135 B CN111947135 B CN 111947135B CN 202010877329 A CN202010877329 A CN 202010877329A CN 111947135 B CN111947135 B CN 111947135B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C7/00—Combustion apparatus characterised by arrangements for air supply
- F23C7/002—Combustion apparatus characterised by arrangements for air supply the air being submitted to a rotary or spinning motion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L13/00—Construction of valves or dampers for controlling air supply or draught
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel
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Abstract
The invention relates to a W flame boiler and a combustion method for ultralow-load dense coal airflow self-stabilized combustion, and aims to solve the problems that the ultralow-load stable combustion capacity of the existing W flame boiler is poor and the flexibility peak load regulation cannot reach 20%. The invention solves the problems that the W flame boiler has ultralow load, stable combustion and flexible peak load regulation, and the opening degree of the carrying air door and the exhaust air volume regulating valve is reasonably adjusted under different load conditions, so that the load can not reach 20%.
Description
Technical Field
The invention relates to a W flame boiler and a combustion method, in particular to a combustion method of a W flame boiler capable of realizing self-stable combustion of ultralow-load concentrated pulverized coal airflow, and relates to the technical field of boilers.
Background
The W-flame boiler is a power station boiler which is introduced from the areas of North Africa and Western Europe and the like from the nineties of the twenty-century in China and is specially designed for burning low-volatile and difficult-to-burn coal types such as lean coal, anthracite and the like. Because the anthracite and lean coal have compact and stable lithofacies structures, small porosity and low reactivity, the problems of difficult ignition, difficult stable combustion and difficult burnout exist in actual combustion, higher ignition temperature and burnout temperature are needed, and the coal powder burnout time is longer. When the boiler is operated under low load, the temperature of the hot air is reduced because the quantity of fuel fed into the boiler is less, and the primary air and the secondary air are reduced along with the reduction of the quantity of the fuel. The oxygen content in the furnace is relatively high, and the heat load in the furnace and the temperature of a hearth are low. The combustion stability of the boiler will be further deteriorated and even cause fire extinguishment. Therefore, the pulverized coal stream is less likely to catch fire and stabilize combustion during low load operation of the W-fired utility boiler than other coal-fired utility boilers.
However, in recent years, with the intervention of large-scale renewable energy sources, the power system in china has changed greatly. The power generation capacity of renewable energy sources accounts for an increasing proportion of the power grid. However, the instability of the output of renewable energy power generation poses a great challenge to the regulation capability of the power system due to the limitations of the power generation mode. In addition, in recent years, while wind power is continuously and rapidly developed, serious wind abandon problems occur in partial areas, and consumption becomes a key factor for restricting the development of new energy resources such as wind power. Therefore, in order to adapt to the high-speed development of renewable energy sources and improve the consumption capacity of a power system for the renewable energy sources, the government requires that the flexibility peak shaving capacity of the boiler reaches about 20% of the full load.
Practical production shows that the minimum load of the W-flame boiler can only be maintained at about 50% of full load under the condition of ensuring the stable operation of the boiler, and the W-flame boiler can not meet relevant government requirements. Therefore, it is necessary to develop a new type of W-flame boiler with flexible peak shaving technology to improve the peak shaving capability of the boiler.
Disclosure of Invention
The invention provides a combustion method of a W flame boiler with thick pulverized coal airflow and wide pulverized coal concentration and speed, aiming at solving the problems that the existing W flame boiler is poor in ultralow-load stable combustion capacity and incapable of reaching 20% of flexible peak load regulation.
The technical scheme adopted by the invention for solving the problems is as follows:
the W flame boiler device and the method for the dense and thin coal airflow wide coal powder concentration and speed comprise a plurality of cyclone tube dense and thin combined coal powder burners, wherein the plurality of cyclone tube dense and thin combined coal powder burners are arranged on the front furnace arch and the rear furnace arch in a straight line shape, each cyclone tube dense and thin combined coal powder burner comprises a dense and thin coal powder airflow nozzle, a ventilation air nozzle and a carrying air nozzle, and the dense and thin coal powder airflow nozzle, the ventilation air nozzle and the carrying air nozzle are coaxially arranged from outside to inside in sequence and are communicated with the boiler body.
Furthermore, the combustion method of the W flame boiler capable of realizing self-stable combustion of the ultralow-load dense pulverized coal airflow further comprises a plurality of secondary oil air nozzles, the plurality of secondary oil air nozzles are arranged on the front furnace arch and the rear furnace arch, each secondary oil air nozzle is arranged on the outer side of the corresponding cyclone cylinder dense-thin combined pulverized coal burner, and the secondary oil air nozzles are communicated with the furnace body.
Furthermore, the area of the exhaust gas nozzle is 2.9-4.4 times of that of the thick pulverized coal airflow nozzle.
Furthermore, the inner diameter (d1) of the exhaust nozzle is 1.3-1.5 times of the diameter of the carrying air nozzle (d 2).
Furthermore, a ventilation air adjusting valve is arranged on a ventilation air pipeline of the pipe air nozzle.
Furthermore, a carrying air door is arranged on the carrying air pipeline of the carrying air nozzle.
Further, when the boiler is started, secondary oil air is sprayed into the boiler from a secondary oil air nozzle and is supplied for oil sprayed out of a large oil gun arranged in the secondary oil air nozzle to be combusted, the output force of the oil gun is 1.0-1.5 t/h, and the oil flame heats the cooling boiler; when the temperature of the flue gas in the hearth reaches 1050-1150 ℃, the coal dust airflow in the primary air pipe enters a cyclone thick-thin combined coal dust burner, and under the separation action of the cyclone, the primary air coal dust airflow is divided into a thick coal dust airflow and a thin coal dust airflow; the exhaust air quantity regulating valve is completely closed, the thick coal powder air flow is downwards sprayed into the hearth from the thick coal powder air flow nozzle, and no light coal powder air flow exists; the oil flame meets the thick coal powder airflow to ignite the thick coal powder airflow; under the combustion supporting of oil flame, the coal feeding amount is gradually increased, and the load of the boiler is gradually increased. When the boiler load reaches 50%, the secondary air of oil is closed, the oil gun stops injecting oil, and the boiler reaches full load by means of the heat released by pulverized coal combustion.
Further, when the boiler is in full-load operation, primary air of the boiler accounts for 20-22% of the total air rate of the boiler; the exhaust air volume regulating valve and the carrying air door are completely closed all the time, primary air pulverized coal airflow is sprayed out from the concentrated pulverized coal airflow nozzle, the air speed is 30-35 m/s, and the mass flow ratio of pulverized coal mass flow to pulverized coal conveying air is 0.4: 1-0.6: 1, unit is kg (coal)/kg (air); when the boiler operates in the interval from 50% load to full load, the opening of the exhaust air volume regulating valve and the carrying air door is 0%; when the load of the boiler is reduced to 20 percent, the exhaust air quantity regulating valve and the carrying air door are gradually opened along with the gradual reduction of the coal powder supply, and the opening increasing value is in direct proportion to the load reduction amplitude.
Further, when the load of the boiler reaches 20% of the ultra-low load operation, the exhaust air volume regulating valve is completely opened, and the primary air pulverized coal airflow is divided into a thick pulverized coal airflow and a thin pulverized coal airflow under the separation action of the cyclone cylinder; the thick coal powder airflow is downwards sprayed into the hearth from a thick coal powder airflow nozzle, and the thin coal powder airflow upwards enters an exhaust pipeline and is finally sprayed into the hearth through an exhaust nozzle; the air flow rate of the thick pulverized coal accounts for 18.5-25.9% of the total primary air rate, the air flow rate of the thin pulverized coal accounts for 74.1-81.5% of the total primary air rate, and the air speeds of the thick pulverized coal and the thin pulverized coal are about 5-7 m/s. The concentrated coal powder airflow accounts for 90% of the total coal feeding amount, the light coal powder airflow accounts for 10% of the total coal feeding amount, and the mass flow ratio of the coal powder mass flow to the air for conveying the coal powder is 1.5: 1-2.4: 1, unit is kg (coal)/kg (air); igniting the thick coal powder airflow at a position 500-600mm away from a thick coal powder airflow nozzle; the carrying air door is completely opened, and the carrying air speed is 23-26 m/s.
Furthermore, after the 20% ultra-low load operation of the boiler is finished, the load is required to be increased, along with the gradual increase of the coal powder supply, the exhaust air volume regulating valve and the carrying air door are gradually closed, and the opening degree reduction value is in direct proportion to the load increase amplitude; when the load is increased to 50% of the load, the exhaust air volume regulating valve is closed, the thick coal powder airflow is downwards sprayed into the hearth from the thick coal powder airflow nozzle, and the air carrying door is completely closed without the thin coal powder airflow.
The invention has the beneficial effects that:
1. the thick coal powder airflow is arranged on the fire-facing side, which is favorable for ignition and stable combustion of the coal powder airflow.
As shown in fig. 1, each double-cyclone thick-thin pulverized coal burner of the conventional FW-type W-flame boiler includes two thick-pulverized coal airflow nozzles and two exhaust gas nozzles. Wherein the exhaust gas nozzle is arranged at the side close to the center of the hearth, and the dense coal powder airflow nozzle is arranged at the side close to the wall of the front wall and the rear wall of the lower hearth. The central area of the hearth has high smoke temperature, and the side hearths of the front wall and the rear wall have low temperature. The thick coal powder airflow is arranged on the front wall side and the rear wall side with low temperature, and the thick coal powder airflow is slow in temperature rise, late in ignition and poor in stable combustion.
As shown in fig. 2 and 3, the exhaust nozzle is coaxially arranged inside the rich coal airflow nozzle. The dense pulverized coal airflow is arranged on the central side of the hearth, the smoke temperature of the central area of the hearth is high, the dense pulverized coal airflow is fast in temperature rise, early in ignition and good in stable combustion.
2. The down-stroke depth of flame can be ensured while the dense coal dust airflow is on fire in time.
Under the original structure, the dense pulverized coal airflow is ensured to be ignited in time and large-depth downward rushing of flame is realized. The air flow velocity of the concentrated coal powder is 27-32 m/s under the full load condition, the concentration is 0.4-0.6 kg (coal)/kg (air), the coal powder concentration is low, the velocity is high, the ignition of the coal powder air flow is not facilitated, but the hearth temperature is 1600-1700 ℃ under the full load condition, the hearth temperature is high, and the stable operation of the boiler can still be realized. At about 50% load, the airflow speed of the concentrated coal powder is reduced to 22-25 m/s, the coal powder concentration is 0.3-0.5 kg/m3, although the temperature of the hearth is reduced relative to the full load, the temperature of the hearth is still as high as 1400-1450 ℃, and the stable operation of the boiler can be still realized. At 20% ultra-low load, the temperature of the hearth is further reduced, generally 1150-1250 ℃, and the propagation speed of the pulverized coal flame is reduced to about 8 m/s. In order to realize the large-depth undershoot of flame, the air speed of the concentrated pulverized coal airflow is still kept to be 22-25 m/s, the pulverized coal concentration is 0.15-0.3 kg (coal)/kg (air), and the concentrated pulverized coal airflow is difficult to catch fire due to the following reasons: (1) the concentration of the coal dust is 0.15-0.3 kg/m3, and the ignition temperature is about 1000 ℃. The coal powder has low concentration and high ignition temperature, and requires much ignition heat. (2) The air speed of the concentrated coal dust airflow is still kept at 22-25 m/s, the residence time in a high-temperature area is short, the temperature of a hearth is only 1150-1250 ℃, and the concentrated coal dust airflow is difficult to heat to the ignition temperature. (3) The necessary conditions for achieving stable combustion: the velocity of the pulverized coal gas flow in the ignition area is equal to or lower than the propagation velocity of the pulverized coal flame. The air speed of the concentrated coal powder airflow is still kept at 22-25 m/s, and the flame propagation speed of the coal powder is far higher than about 8m/s within the ignition distance of 500-600mm at the outlet of the concentrated coal powder airflow. Therefore, the high wind speed of the concentrated coal powder airflow meets the requirement of large-depth undershoot of flame, but cannot realize timely ignition and stable combustion of the 20% ultra-low load concentrated coal powder airflow. In order to meet the requirements of timely ignition and stable combustion of the 20% ultra-low load concentrated pulverized coal airflow, the airflow speed of the concentrated pulverized coal airflow is reduced to 5-7 m/s under the original structure. Because the air flow velocity of the concentrated coal dust is too low and the momentum is small, the downward-rushing depth of the concentrated coal dust air flow is greatly reduced, the retention time of the concentrated coal dust air flow in a lower hearth is short, the heat released by combustion is small, and the smoke temperature of the lower hearth can be reduced to below 1000 ℃ at this time, so that the ignition and the combustion of the coal dust air flow are difficult to maintain. Therefore, the low wind speed of the concentrated coal powder airflow is difficult to meet the requirement of large-depth undershoot of flame, so that the flue gas temperature of a hearth is further reduced, and the 20% ultralow load stable combustion cannot be realized. Therefore, under the original structure, the thick pulverized coal airflow can not only ensure timely ignition, but also realize large-depth undershoot of flame, and can not realize 20% ultra-low load stable combustion.
The air flow velocity of the thick and thin pulverized coal is 5-7 m/s, the undershoot momentum is small, and the undershoot depth is small. The speed of the carried wind is 27-32 m/s, the speed is high, and the momentum is large. The thick and thin coal dust airflow is ejected from the nozzle and then carried downwards under the ejection effect of the carrying wind, so that the downward-punching depth of the flame is ensured. The flame is deeply downwards pushed to the vicinity of the cold ash hopper and then turns upwards, the residence time of the concentrated coal powder airflow in the lower hearth is long, the combustion time is long, and the heat released by combustion is large, so that the lower hearth is ensured to have higher flue gas temperature, and the higher flue gas temperature is favorable for the concentrated coal powder airflow to catch fire. Therefore, the high-speed air is coaxially arranged in the thick coal dust airflow and the thin coal dust airflow, and the down-stroke depth of the flame is ensured.
The invention can ensure the thick coal powder airflow to catch fire in time for the following reasons: (1) the concentration of the concentrated coal dust airflow coal dust is 1.5-2.4 kg (coal)/kg (air). The higher the coal powder concentration is, the lower the ignition temperature is, which is about 600 ℃, and compared with the original structure, the ignition temperature is reduced by about 400 ℃, which is beneficial to the timely ignition of dense coal powder airflow. (2) The air flow speed of the concentrated coal powder is 5-7 m/s, when the air flow speed of the concentrated coal powder is 20-25 m/s, the staying time of the concentrated coal powder air flow in a high-temperature area is prolonged by about 4 times, the longer the staying time in the high-temperature area is, the longer the coal powder heating time is, the larger the temperature rise in a unit distance is, and the timely ignition of the concentrated coal powder air flow is facilitated. (3) The air flow velocity of the concentrated coal dust is 5-7 m/s, and is lower than the coal dust flame propagation velocity of about 8m/s, so that the air flow velocity of the coal dust in an ignition area is equal to or lower than the coal dust flame propagation velocity. (4) After the thick coal airflow is ignited, the exhaust gas and the carrying air are gradually mixed with the thick coal airflow and supply the air required by the thick coal airflow for combustion, the thick coal airflow is combusted in the lower hearth to release more heat, and the lower hearth has high temperature, so that the thick coal airflow is favorable for ignition.
The invention ensures the timely ignition of the thick pulverized coal airflow, realizes the larger undershoot depth of the flame, and can realize the stable combustion of 20 percent of ultralow load.
3. The high-load and about 50% low-load operation mode is not influenced.
Under the conditions of high load and about 50% low load, the boiler can completely recover the operation mode of the traditional boiler by closing the exhaust air volume regulating valve and the opening of the carrying air door. The air speed of the thick coal powder airflow under the full load condition is about 30-35 m/s, and the concentration of the coal powder is 0.4-0.6 kg (coal)/kg (air). Under the condition of about 50% load, the air flow speed of the concentrated pulverized coal is reduced to 25-28 m/s, the concentration of the pulverized coal is 0.3-0.5 kg (coal)/kg (air), and the stable and efficient operation of the boiler is not influenced.
4. The adjusting means is reliable, and large-range lifting load can be stably realized.
Under the original structure, the load is lifted only by adjusting the airflow speed of the concentrated coal powder, the adjusting means is single, the operation in the load range of 50% -100% can be realized only, and the requirement of flexible peak regulation is difficult to meet. The invention realizes the operation in the load range of 20-100% by adjusting the opening of the exhaust air volume adjusting valve and the carrying air door, and meets the requirement of flexible peak regulation.
Drawings
FIG. 1 is a schematic cross-sectional flow field diagram of a conventional FW type flame boiler;
FIG. 2 is a schematic cross-sectional flow field of the W flame boiler of the present invention;
fig. 3 is a partially enlarged view of fig. 2.
Detailed Description
The first embodiment is as follows: the present embodiment is described with reference to fig. 2 to 3, and the present embodiment provides a W flame boiler with a rich coal airflow and a wide coal concentration and velocity, which includes an upper furnace 1, a lower furnace 2, a front arch 3, a rear arch 4, and a plurality of layers of arch-down secondary air nozzles 8, wherein the upper furnace 1, the lower furnace 2, the front arch 3, and the rear arch 4 form a furnace body, the plurality of layers of arch-down secondary air nozzles 8 are sequentially disposed on a front wall and a rear wall of the lower furnace from top to bottom, the W flame boiler with the rich coal airflow and the wide coal concentration and velocity further includes a plurality of cyclone thick-thin combined coal burners 5, the plurality of cyclone thick-thin combined coal burners 5 are installed on the front arch 3 and the rear arch 4 in a straight line shape, the W flame boiler with the rich coal airflow and the wide coal concentration and velocity further includes a plurality of cyclone thick-thin combined coal burners 5, the multiple cyclone tube rich-lean combined type pulverized coal burners 5 are arranged on the front furnace arch 3 and the rear furnace arch 4 in a straight shape, each cyclone tube rich-lean combined type pulverized coal burner 5 comprises a rich pulverized coal airflow nozzle 6, a ventilation air nozzle 7 and a carrying air nozzle 10, and the rich pulverized coal airflow nozzle 6, the ventilation air nozzle 7 and the carrying air nozzle 10 are sequentially and coaxially arranged from outside to inside and are all communicated with a furnace body.
The second embodiment is as follows: the embodiment is described with reference to fig. 2 to 3, and the area of the exhaust gas nozzle 7 is 2.9 to 4.4 times of the area of the rich pulverized coal airflow nozzle 6 in the embodiment.
Other components are connected in the same manner as in the second embodiment.
The third concrete implementation mode: the embodiment is described with reference to fig. 2 to 3, and the inner diameter d1 of the exhaust air nozzle 7 of the embodiment is 1.3 to 1.5 times of the diameter of the carrying air nozzle.
Other components and connection relationships are the same as those in the first, second or third embodiment.
The fourth concrete implementation mode: the embodiment is described with reference to fig. 2 to 3, and a ventilation air adjusting valve 9 is provided on the ventilation air pipeline of the tubular air nozzle 7 in the embodiment.
The air quantity in the exhaust nozzle 7 can be adjusted by 0-100% by controlling the opening of the exhaust air quantity adjusting valve 9.
Other components and connections are the same as those of the first, second, third or fourth embodiments.
The fifth concrete implementation mode: the present embodiment will be described with reference to fig. 2 to 3, and the carrier air door 11 is provided in the carrier air duct of the carrier air nozzle 10 according to the present embodiment.
The adjustment of 1-100% of the internal air volume of the air carrying nozzle 10 can be realized by controlling the opening of the air carrying door 11.
Other components and connection relationships are the same as those in the first, second, third, fourth or fifth embodiment.
The sixth specific implementation mode: the embodiment is described with reference to fig. 2 to 3, the W-flame boiler with self-stabilized combustion of ultralow-load rich pulverized coal airflow according to the embodiment further includes a plurality of secondary oil air nozzles 12, the plurality of secondary oil air nozzles 12 are installed on the front furnace arch 3 and the rear furnace arch 4, each secondary oil air nozzle 12 is disposed outside a corresponding cyclone thick-thin combined pulverized coal burner 5, and the secondary oil air nozzles 12 are communicated with the furnace body. Each cyclone tube shade combined pulverized coal burner 5 is provided with an oil secondary air nozzle 12.
Other components and connections are the same as those in the first embodiment.
The seventh embodiment: the embodiment is described with reference to fig. 2 to 3, when the boiler is started, the secondary oil air is sprayed into the boiler from the secondary oil air nozzles 12 and supplied to oil sprayed from a large oil gun arranged in the secondary oil air nozzles 12 for combustion, the output of the oil gun is 1.0 to 1.5t/h, and the oil flame heats the cold boiler;
when the temperature of the hearth flue gas reaches 1050-1150 ℃, the coal dust airflow in the primary air pipe enters a cyclone thick-thin combined coal dust burner 5, and under the separation action of the cyclone, the primary air coal dust airflow is divided into a thick coal dust airflow and a thin coal dust airflow; the exhaust air volume regulating valve 9 is completely closed, the thick coal powder air flow is downwards sprayed into the hearth from the thick coal powder air flow nozzle 6, and no light coal powder air flow exists; the oil flame meets the thick coal powder airflow to ignite the thick coal powder airflow; under the combustion supporting of oil flame, the coal feeding amount is gradually increased, and the load of the boiler is gradually increased; when the boiler load reaches 50%, oil secondary air is closed, oil gun oil injection is stopped, the boiler reaches full load by means of heat released by pulverized coal combustion, and when the boiler runs at full load, primary air of the boiler accounts for 20-22% of the total air rate of the boiler; the exhaust air volume regulating valve 9 and the carrying air door 11 are completely closed all the time, the primary air pulverized coal airflow is sprayed out from the concentrated pulverized coal airflow nozzle 6, the air speed is 27-32 m/s, and the mass flow ratio of pulverized coal mass flow to the air for conveying pulverized coal is 0.4: 1-0.6: 1, unit is kg (coal)/kg (air);
when the boiler operates in the interval from 50% load to full load, the opening of the exhaust air volume regulating valve 9 and the carrying air door 11 is 0%; when the load of the boiler is reduced to 20 percent, the exhaust air quantity regulating valve 9 and the carrying air door 11 are gradually opened along with the gradual reduction of the coal powder supply, and the opening increasing value is in direct proportion to the load reduction amplitude;
when the load of the boiler reaches 20 percent of ultra-low load operation, the exhaust air volume regulating valve 9 is completely opened, and the primary air coal dust airflow is divided into a thick coal dust airflow and a thin coal dust airflow under the separation action of the cyclone cylinder; the thick coal powder airflow is downwards sprayed into the hearth from a thick coal powder airflow nozzle 6, and the thin coal powder airflow upwards enters an exhaust pipeline and is finally sprayed into the hearth through an exhaust nozzle 7; the air flow rate of the thick pulverized coal accounts for 18.5-25.9% of the total primary air rate, the air flow rate of the thin pulverized coal accounts for 74.1-81.5% of the total primary air rate, and the air speeds of the thick pulverized coal and the thin pulverized coal are about 5-7 m/s; the concentrated coal powder airflow accounts for 90% of the total coal feeding amount, the light coal powder airflow accounts for 10% of the total coal feeding amount, and the mass flow ratio of the coal powder mass flow to the air for conveying the coal powder is 1.5: 1-2.4: 1, unit is kg (coal)/kg (air); igniting the thick coal powder airflow at a position 6500-600 mm away from a thick coal powder airflow nozzle; the carrying air door 11 is completely opened, and the carrying air speed is 23-26 m/s.
The specific implementation mode is eight: the embodiment is described with reference to fig. 2 to fig. 3, after the operation of the boiler with 20% ultra-low load is finished, the load is required to be increased, the exhaust air volume adjusting valve 9 and the carrying air door 11 are gradually closed along with the gradual increase of the coal powder supply, and the opening degree decrease value is in direct proportion to the load increase amplitude; when the load is increased to 50 percent, the exhaust air volume adjusting valve 9 is closed, the thick coal powder air flow is downwards sprayed into the hearth from the thick coal powder air flow nozzle 6, no thin coal powder air flow exists, and the carrying air door 11 is completely closed.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (6)
1. A combustion method of a W flame boiler with ultra-low load concentrated pulverized coal airflow self-stabilizing combustion is used, and the W flame boiler with the ultra-low load concentrated pulverized coal airflow self-stabilizing combustion comprises the following steps: an upper hearth (1), a lower hearth (2), a front furnace arch (3), a rear furnace arch (4), a plurality of cyclone thick-thin combined pulverized coal burners (5), a plurality of layers of arch lower secondary air nozzles (8) and a plurality of oil secondary air nozzles (12), the upper hearth (1), the lower hearth (2), the front furnace arch (3) and the rear furnace arch (4) form a furnace body, the secondary air nozzles (8) under the multiple layers of arches are sequentially arranged on the front wall and the rear wall of the lower hearth (2) from top to bottom, the multiple cyclone tube thick and thin combined coal powder burners (5) are arranged on the front furnace arch (3) and the rear furnace arch (4) in a straight line shape, each cyclone tube thick and thin combined coal powder burner (5) comprises a thick coal powder airflow nozzle (6), an exhaust gas nozzle (7) and a carrying air nozzle (10), the concentrated coal powder airflow nozzle (6), the exhaust gas nozzle (7) and the air carrying nozzle (10) are coaxially arranged from outside to inside in sequence and are communicated with the furnace body; a plurality of secondary oil air nozzles (12) are arranged on the front furnace arch (3) and the rear furnace arch (4), each secondary oil air nozzle (12) is arranged at the outer side of a corresponding cyclone thick-thin combined pulverized coal burner (5), and the secondary oil air nozzles (12) are communicated with the furnace body;
the method is characterized in that: a combustion method of a W flame boiler with ultralow-load concentrated pulverized coal airflow self-stabilizing combustion comprises the following steps:
when the boiler is started, secondary oil air is sprayed into the boiler from the secondary oil air nozzle (12) and supplied to oil sprayed from a large oil gun arranged in the secondary oil air nozzle (12) for combustion, the output of the oil gun is 1.0-1.5 t/h, and the oil flame heats the cooling boiler;
when the temperature of the flue gas in the hearth reaches 1050-1150 ℃, the coal dust airflow in the primary air pipe enters a cyclone thick-thin combined coal dust burner (5), and under the separation action of the cyclone, the primary air coal dust airflow is divided into a thick coal dust airflow and a thin coal dust airflow; the exhaust air volume regulating valve (9) is completely closed, the thick coal powder airflow is downwards sprayed into the hearth from the thick coal powder airflow nozzle (6), and no light coal powder airflow exists; the oil flame meets the thick coal powder airflow to ignite the thick coal powder airflow; under the combustion supporting of oil flame, the coal feeding amount is gradually increased, and the load of the boiler is gradually increased; when the boiler load reaches 50%, oil secondary air is closed, oil gun oil injection is stopped, the boiler reaches full load by means of heat released by pulverized coal combustion, and when the boiler runs at full load, primary air of the boiler accounts for 20-22% of the total air rate of the boiler; the exhaust air volume regulating valve (9) and the carrying air door (11) are completely closed all the time, primary air pulverized coal airflow is sprayed out from the concentrated pulverized coal airflow nozzle (6), the air speed is 27-32 m/s, and the mass flow ratio of pulverized coal mass flow to the mass flow of air for conveying pulverized coal is 0.4: 1-0.6: 1;
when the boiler operates in the interval from 50% load to full load, the opening of the exhaust air volume regulating valve (9) and the carrying air door (11) is 0%; when the load of the boiler is reduced to 20 percent, the exhaust air quantity regulating valve (9) and the carrying air door (11) are gradually opened along with the gradual reduction of the coal powder supply, and the opening increasing value is in direct proportion to the load reduction amplitude;
when the load of the boiler reaches 20 percent and the ultra-low load operation is carried out, the exhaust air volume regulating valve (9) is completely opened, and the primary air pulverized coal airflow is divided into a thick pulverized coal airflow and a thin pulverized coal airflow under the separation action of the cyclone cylinder; the thick coal powder airflow is downwards sprayed into the hearth from a thick coal powder airflow nozzle (6), and the thin coal powder airflow upwards enters an exhaust pipeline and is finally sprayed into the hearth through an exhaust nozzle (7); the air flow rate of the thick pulverized coal accounts for 18.5-25.9% of the total primary air rate, the air flow rate of the thin pulverized coal accounts for 74.1-81.5% of the total primary air rate, and the air speeds of the thick pulverized coal and the thin pulverized coal are about 5-7 m/s; the concentrated coal powder airflow accounts for 90% of the total coal feeding amount, the light coal powder airflow accounts for 10% of the total coal feeding amount, and the mass flow ratio of the coal powder mass flow to the air for conveying the coal powder is 1.5: 1-2.4: 1; the thick coal powder airflow is ignited at a position 500-600mm away from the thick coal powder airflow nozzle (6); the carrying air door (11) is completely opened, and the carrying air speed is 23-26 m/s.
2. The combustion method of the W-flame boiler capable of realizing self-stable combustion of the ultralow-load concentrated pulverized coal airflow according to claim 1, is characterized in that: after the operation of the boiler with 20 percent of ultralow load is finished, the load is required to be increased, along with the gradual increase of the coal powder supply, the exhaust air volume regulating valve (9) and the carrying air door (11) are gradually closed, and the opening degree reduction value is in direct proportion to the load increase amplitude; when the load is increased to 50 percent of the load, the exhaust air volume adjusting valve (9) is closed, the thick coal powder airflow is downwards sprayed into the hearth from the thick coal powder airflow nozzle (6), and the air carrying door (11) is completely closed without the thin coal powder airflow.
3. The combustion method of the W-flame boiler capable of realizing self-stable combustion of the ultralow-load concentrated pulverized coal airflow according to claim 1, is characterized in that: the area of the exhaust gas nozzle (7) is 2.9-4.4 times of that of the dense coal powder airflow nozzle (6).
4. The combustion method of the W-flame boiler capable of realizing self-stable combustion of the ultralow-load concentrated pulverized coal airflow according to claim 1, is characterized in that: the inner diameter (d1) of the ventilation air nozzle (7) is 1.3-1.5 times of the diameter of the carrying air nozzle (d 2).
5. The combustion method of the W-flame boiler capable of realizing self-stable combustion of the ultralow-load concentrated pulverized coal airflow according to claim 1, is characterized in that: an exhaust air volume regulating valve (9) is arranged on an exhaust pipeline of the exhaust air nozzle (7).
6. The combustion method of the W-flame boiler capable of realizing self-stable combustion of the ultralow-load concentrated pulverized coal airflow according to claim 1, is characterized in that: a carrying air door (11) is arranged on the carrying air pipeline of the carrying air nozzle (10).
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| CN101545639A (en) * | 2009-05-08 | 2009-09-30 | 哈尔滨工业大学 | Method for adjusting combustion of W flame furnace by changing quantity of oil secondary air |
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