Combustion system and combustion method for improving flexibility of coal types of W flame boiler
阅读说明：本技术 一种提高w火焰锅炉煤种灵活性的燃烧系统及燃烧方法 (Combustion system and combustion method for improving flexibility of coal types of W flame boiler ) 是由 赖金平 杨希刚 陈国庆 戴维葆 何陆灿 刘铭媛 于 2019-11-01 设计创作，主要内容包括：本发明公开了一种提高W火焰锅炉煤种灵活性的燃烧系统及燃烧方法。该燃烧系统设于W火焰锅炉内,包括若干分布于炉膛拱部位置处的燃烧器、与各燃烧器对应设置的主燃烧器喷口；本发明燃烧系统还包括若干组与燃烧器一一对应的乏气调节装置；每组乏气调节装置均包括三路乏气管道,各路乏气管道分别连通该组乏气调节装置对应的燃烧器与对应的乏气喷口,每组乏气管道的三个乏气喷口分别设于上炉膛前墙、炉膛拱部、下炉膛垂直墙位置处；各乏气管道上均设有乏气可调缩孔。本发明通过对乏气管管道的多路设计,能够针对不同的煤种进行乏气通入的调节,以适应宽煤种的应用。(The invention discloses a combustion system and a combustion method for improving the flexibility of coal types of a W flame boiler. The combustion system is arranged in a W flame boiler and comprises a plurality of burners distributed at the arch part of a hearth and main burner nozzles arranged corresponding to the burners; the combustion system also comprises a plurality of groups of exhaust gas adjusting devices which correspond to the combustors one by one; each group of exhaust gas adjusting devices comprises three paths of exhaust gas pipelines, each path of exhaust gas pipeline is respectively communicated with a corresponding combustor and a corresponding exhaust gas nozzle of the group of exhaust gas adjusting devices, and the three exhaust gas nozzles of each group of exhaust gas pipelines are respectively arranged at the positions of the front wall of the upper hearth, the arch part of the hearth and the vertical wall of the lower hearth; each exhaust pipeline is provided with an exhaust adjustable shrinkage cavity. The invention can adjust the ventilation of the exhaust gas aiming at different coal types by the multi-path design of the exhaust gas pipe so as to adapt to the application of wide coal types.)
1. A combustion system for improving coal flexibility of a W flame boiler is arranged in the W flame boiler and comprises a plurality of burners distributed at the arch part of a hearth and main burner nozzles arranged corresponding to the burners; the method is characterized in that: the combustion system also comprises a plurality of groups of exhaust gas adjusting devices which correspond to the combustors one by one; each group of exhaust gas adjusting devices comprises three paths of exhaust gas pipelines, each path of exhaust gas pipeline is respectively communicated with a corresponding combustor and a corresponding exhaust gas nozzle of the group of exhaust gas adjusting devices, and the three exhaust gas nozzles of each group of exhaust gas pipelines are respectively arranged at the positions of the front wall of the upper hearth, the arch part of the hearth and the vertical wall of the lower hearth; each exhaust pipeline is provided with an exhaust adjustable shrinkage cavity.
2. The combustion system of claim 1, wherein: the nozzles arranged on the front wall of the upper hearth and the vertical wall of the lower hearth are provided with adjustable exhaust nozzles.
3. The combustion system of claim 2, wherein: the periphery of each adjustable exhaust nozzle is provided with an annular peripheral air distribution device.
4. The combustion system of claim 3, wherein: the combustion system further comprises a plurality of over-fire air nozzles, and each over-fire air nozzle is arranged at the upper positions of the front wall of the upper hearth and the exhaust air nozzle.
5. The combustion system of claim 4, wherein: the combustion system further comprises a plurality of auxiliary over-fire air nozzles, and the auxiliary over-fire air nozzles are arranged above the over-fire air nozzles and distributed in a tangent circle mode.
6. The combustion system of claim 5, wherein: the combustion system further comprises a plurality of grading air nozzles, and each grading air nozzle is arranged above the lower furnace chamber vertical wall and the exhaust air nozzle.
7. A combustion method for improving flexibility of coal types of a W flame boiler is characterized by comprising the following steps: according to the combustion method, when different coal types are adopted by the boiler, the position and the injection angle of exhaust gas injected into the hearth are regulated and controlled.
8. The combustion method as set forth in claim 7, characterized in that: the combustion method specifically adjusts and controls the position of exhaust gas sprayed into a hearth according to different coal types as follows: when the boiler burns bituminous coal with dry ash-free base volatile component more than 30%, controlling the exhaust gas to be sprayed into a hearth from an upper hearth; when dry anthracite and lean coal without ash base volatile component less than 20% are combusted by the boiler, controlling exhaust gas to be sprayed into a hearth from a lower hearth; when the boiler is burning bituminous coal whose volatile component is 20-30%, the waste gas is controlled to be sprayed into the furnace cavity from the arch portion.
9. The combustion method as set forth in claim 7, characterized in that: the method for regulating and controlling the angle of exhaust gas sprayed into the hearth by the combustion method comprises the following steps: when the amount of the desuperheating water is larger or the wall of the high-temperature superheater is overhigh, the angle of the exhaust gas nozzle is adjusted downwards; when the main air temperature of the boiler or the temperature of the reheater is lower, the angle of the exhaust air nozzle is adjusted upwards.
10. The combustion method as set forth in claim 8, wherein: according to the combustion method, when loads of boiler operation units are different, the position of exhaust gas sprayed into a hearth is regulated and controlled as follows: when the load of the boiler is low, the exhaust gas is controlled to be sprayed into the hearth from the arch part; when the load of the boiler is higher, the exhaust gas injection mode is controlled by adopting the specific regulation and control method for injecting the exhaust gas into the hearth position aiming at different coal types.
Technical Field
The invention relates to a W flame boiler combustion system, in particular to a combustion system of a W flame boiler with wide coal types, and belongs to the technical field of electric power and power engineering.
Background
The W flame boiler is a boiler developed by Foster Whiler company in America and specially used for burning low-volatile coal, and has obvious advantages when low-volatile coal such as anthracite, inferior lean coal and the like is burned. The lower hearth of the W flame boiler is 80-120% larger than the upper hearth, the front and back protruded furnace tops form a furnace arch, the pulverized coal nozzle is arranged on the furnace arch and is downwards sprayed into the hearth, and when pulverized coal airflow flows downwards and expands, the pulverized coal flows upwards in a 180-degree turn after meeting secondary air at the lower part of the hearth, so that W-shaped flame is formed. In order to ensure that the pulverized coal is timely ignited, stably combusted and completely combusted, the W flame boiler usually adopts measures of low wind speed, high pulverized coal concentration, high wind temperature, burner area laying of a combustion guard and the like, but some measures generate contradiction with NOx reduction, so that the NOx emission concentration of the W flame boiler is generally higher, and meanwhile, the coal type adaptability of the W flame boiler is poorer due to the special combustion characteristic of the W flame boiler.
With the stricter and stricter environmental protection requirements of China, the ultra-clean emission requirements are put forward on coal-fired boilers in certain areas, and W flame boilers have combustion characteristics, NOxThe emission concentration is generally 1200mg/m3Left and right. Achieving ultra-low emissions is generally achieved with low NOxCombustion technology and SCR flue gas denitration technology. Existing low NOxCombustion technology typically employs low NOxThe burner is matched with the over-fire air.
Because the existing low NOx combustion technology is designed for specific designed coal types, the coal type adaptability is poor. The coal types and the price fluctuation of the power coal in China are large, so that the actual coal types for burning of the coal-fired power plant are large, the content span of the dry ash-free base volatile matter is 8-35%, and the prior art cannot adapt to the actual coal-fired requirement of the power plant.
The installed capacity of a coal-fired power plant in China is in a saturated state, and new energy generating sets are gradually increased, so that the coal-fired generating sets are required to have higher flexibility in deep peak shaving, and the existing technology cannot meet the requirement of adjusting the flexibility of the generating sets.
Meanwhile, because the W flame boiler burner is arranged at the front arch part and the rear arch part, the hearth thermal deviation is easily formed in different burner operation modes, and the problem of the W flame boiler thermal deviation cannot be solved in the prior art.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a combustion mode which is suitable for a W flame boiler and can realize wide coal combustion and high-flexibility adjustment.
In order to achieve the aim, the invention provides a combustion system for improving the coal flexibility of a W flame boiler, which is arranged in the W flame boiler and comprises a plurality of burners distributed at the arch part of a hearth and main burner nozzles arranged corresponding to the burners; the combustion system also comprises a plurality of groups of exhaust gas adjusting devices which correspond to the combustors one by one; each group of exhaust gas adjusting devices comprises three paths of exhaust gas pipelines, each path of exhaust gas pipeline is respectively communicated with a corresponding combustor and a corresponding exhaust gas nozzle of the group of exhaust gas adjusting devices, and the three exhaust gas nozzles of each group of exhaust gas pipelines are respectively arranged at the positions of the front wall of the upper hearth, the arch part of the hearth and the vertical wall of the lower hearth; each exhaust pipeline is provided with an exhaust adjustable shrinkage cavity.
Through the setting of three routes exhaust gas pipeline, can correspond the position that adjusts the exhaust gas and spout into furnace to adapt to different coal types burning demands.
Wherein, the spouts arranged at the positions of the front wall of the upper hearth and the vertical wall of the lower hearth are provided with adjustable exhaust nozzles.
The spraying angle of the exhaust gas sprayed into the upper hearth and the lower hearth can be effectively adjusted through the adjustable exhaust gas nozzles, so that the central height of the flame of the boiler can be adjusted.
The periphery of each adjustable exhaust nozzle is provided with an annular peripheral air distribution device.
The combustion system further comprises a plurality of over-fire air nozzles, and each over-fire air nozzle is arranged at the upper position of the front wall of the upper hearth and the upper position of the exhaust air nozzle.
The combustion system further comprises a plurality of auxiliary over-fire air nozzles, and the auxiliary over-fire air nozzles are arranged above the over-fire air nozzles and distributed in a tangent circle manner.
The tangential auxiliary over-fire air can eliminate the left and right thermal deviation of the hearth and ensure that the temperature deviation at two sides is in a reasonable range.
The combustion system also comprises a plurality of grading air nozzles, and each grading air nozzle is arranged above the vertical wall of the lower hearth and the exhaust air nozzle.
The invention also provides a combustion method for improving the flexibility of the coal type of the W flame boiler, and the combustion method regulates and controls the position and the injection angle of the exhaust gas injected into the hearth when different coal types are adopted by the boiler.
The specific regulation and control method of the combustion method for the position of the exhaust gas sprayed into the hearth aiming at different coal types comprises the following steps: when the boiler burns bituminous coal with dry ash-free base volatile component more than 30%, controlling the exhaust gas to be sprayed into a hearth from an upper hearth; when dry anthracite and lean coal without ash base volatile component less than 20% are combusted by the boiler, controlling exhaust gas to be sprayed into a hearth from a lower hearth; when the boiler is burning bituminous coal whose volatile component is 20-30%, the waste gas is controlled to be sprayed into the furnace cavity from the arch portion.
The method for regulating and controlling the angle of the exhaust gas sprayed into the hearth by the combustion method comprises the following steps: when the amount of the desuperheating water is larger or the wall of the high-temperature superheater is overhigh, the angle of the exhaust gas nozzle is adjusted downwards; when the main air temperature of the boiler or the temperature of the reheater is lower, the angle of the exhaust air nozzle is adjusted upwards.
According to the combustion method, when the loads of the boiler operation units are different, the position of exhaust gas sprayed into the hearth is regulated and controlled. The specific regulation and control method comprises the following steps: when the load of the boiler is low, the exhaust gas is controlled to be sprayed into the hearth from the arch part; when the load of the boiler is higher, the exhaust gas injection mode is controlled by adopting the specific regulation and control method for injecting the exhaust gas into the hearth position aiming at different coal types.
Compared with the prior art, the invention has the following advantages:
1. the invention can adjust the ventilation of the exhaust gas aiming at different coal types by the multi-path design of the exhaust gas pipe so as to adapt to the application of wide coal types;
2. meanwhile, the exhaust gas nozzles with adjustable structures are arranged at the exhaust gas nozzles of the upper hearth and the lower hearth, so that the exhaust gas spraying angle can be adjusted, the adjustment of the central height of flame is realized, and the air temperature and the desuperheating water amount are ensured to be in a reasonable range;
3. and the annular peripheral air is arranged around the exhaust air nozzle, so that the exhaust air can be wrapped, the exhaust air nozzle is prevented from coking, and meanwhile, the exhaust air nozzle can be cooled when the exhaust air is stopped, and the exhaust air nozzle is prevented from being burnt out.
4. The combustion method can adopt different combustion modes aiming at different coal qualities and different loads, and effectively realizes the high-efficiency low-pollutant-emission combustion and high-flexibility regulation of the W boiler under wide coal types.
Drawings
FIG. 1 is a schematic view of the combustion system of the present invention;
FIG. 2 is a schematic view of a group of exhaust gas conditioning devices in the combustion system of the present invention;
FIG. 3 is a schematic view of the distribution of auxiliary overfire air in the combustion system of the present invention;
FIG. 4 is a schematic view of the adjustable exhaust nozzle and the adjustable exhaust nozzle adjusting device shown in FIG. 2;
fig. 5 is a schematic structural view of the annular peripheral wind distribution device in fig. 2.
In the figure, 1-a combustor, 2, 3, 10-an exhaust gas adjustable shrinkage hole, 4, 5, 11-an exhaust gas pipeline, 6-an over-fire air nozzle, 7-an upper hearth front wall, 71-an upper hearth rear wall, 72-an upper hearth left side wall, 73-an upper hearth right side wall, 8-a grading air nozzle, 9-a hearth arch part, 12, 13-an annular periphery air distribution device, 12-1 air distribution cylinder, 12-2 annular periphery, 14-a lower hearth vertical wall, 15, 16-an adjustable exhaust gas nozzle, 17-an auxiliary over-fire air nozzle, 18, 19-an adjustable exhaust gas nozzle adjusting device, 19-1-an electric actuator, 19-2, 19-3-an adjusting connecting rod and 20-a large air box.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
As shown in figure 1, the combustion system of the invention is used for a W flame boiler and comprises a combustor 1, an exhaust gas adjustable shrinkage hole 2/3/10, an exhaust gas pipeline 4/5/11, an adjustable
With reference to fig. 2, the burner 1 is arranged on the furnace arch 9; the exhaust adjustable shrinkage holes 2/3/10 are respectively arranged on the exhaust pipelines 5/4/11; the exhaust gas pipes 4/5/11 are all led out by the burners, wherein the exhaust gas pipes 4 are arranged on the
Because the burners of the W flame boiler are arranged at the arch part along the width direction of the hearth, the uneven combustion of the pulverized coal and the shutdown of the burners can cause the left and right deviation of the temperature of the hearth. The auxiliary over-fire
The
As shown in FIG. 5, the annular peripheral
The pulverized coal airflow is divided into main air and exhaust air through an elbow on the combustor 1.
Firstly, adjusting according to the load of the boiler:
1. when the boiler load is lower (the boiler load is less than 50 percent BMCR), the two exhaust gas pipelines 4/11 can be closed through the exhaust gas adjustable shrinkage holes 3/10, and the exhaust gas is sprayed into the hearth from the arch part through the exhaust gas pipeline 5. Because the downward momentum of the arch part is insufficient in low load, the downward momentum of the arch part of the boiler can be increased by injecting exhaust gas from the arch part, and the filling degree of the flame in the lower hearth can be increased.
2. Under the condition of other boiler loads, adjusting according to coal types:
when the boiler burns bituminous coal with dry ash-free base volatile matter more than 30%, the two exhaust gas pipelines 5/11 can be closed through the exhaust gas adjustable shrinkage cavity 2/10, and the exhaust gas is sprayed into a hearth from an upper hearth through the exhaust gas pipeline 4. Because the coal has high volatile matter and is easy to burn out, the exhaust gas can be effectively burnt out when being sprayed into the upper hearth, and meanwhile, the fuel is combusted in a grading way, so that the NO is further reducedxAnd (3) discharging, wherein the spraying angle of the exhaust gas can be adjusted through the adjustable exhaust gas nozzle adjusting device 19, the central height of the flame of the boiler is adjusted, and further the air temperature and the desuperheating water quantity of the boiler are adjusted.
Furthermore, the adjustment mode of the spraying angle of the exhaust gas in the upper furnace chamber is as follows:
when the amount of the desuperheating water is too large or the wall of the high-temperature superheater is too high, the angle of the exhaust gas nozzle is adjusted downwards, the height of the flame center of the hearth is reduced, the amount of the desuperheating water is further reduced, and the safe and economic operation of the boiler is ensured. The temperature-reducing water quantity and the wall temperature condition are observed to be adjusted after adjustment at 5 degrees every time.
When the main temperature of the boiler or the temperature of the reheater is lower, the angle of the exhaust nozzle is adjusted upwards, and further the height of the flame center of the hearth is increased, so that the main temperature of the boiler and the temperature of the reheater are increased, and the safe and economic operation of the boiler is guaranteed. The temperature-reducing water quantity and the wall temperature condition are observed to be adjusted after adjustment at 5 degrees every time.
When the boiler burns anthracite and lean coal with dry ash-free base volatile matter less than 20%, the two exhaust gas pipelines 5/4 can be closed through the exhaust gas adjustable shrinkage cavity 2/3, and the exhaust gas is sprayed into the hearth from the lower hearth through the
Furthermore, the adjustment mode of the spraying angle of the exhaust gas of the lower furnace chamber is as follows:
when the amount of the desuperheating water is too large or the wall of the high-temperature superheater is too high, the angle of the exhaust gas nozzle is adjusted downwards, the height of the flame center of the hearth is reduced, the amount of the desuperheating water is further reduced, and the safe and economic operation of the boiler is ensured. The temperature-reducing water quantity and the wall temperature condition are observed to be adjusted after adjustment at 5 degrees every time.
When the main temperature of the boiler or the temperature of the reheater is lower, the angle of the exhaust nozzle is adjusted upwards, and further the height of the flame center of the hearth is increased, so that the main temperature of the boiler and the temperature of the reheater are increased, and the safe and economic operation of the boiler is guaranteed. The temperature-reducing water quantity and the wall temperature condition are observed to be adjusted after adjustment at 5 degrees every time.
When dry ash-free base volatile matter for boiler is between 20% and 30% of bituminous coal, the two exhaust gas pipelines 4/11 can be closed through the exhaust gas adjustable shrinkage holes 3/10, and exhaust gas is sprayed into a hearth from an arch part through the exhaust gas pipeline 5. The exhaust gas is sprayed into the hearth from the arch part, so that the downward momentum of the arch part can be increased, and the flame filling degree of the hearth is improved.
The combustion combination modes of the invention are not limited to the above listed modes, and various combustion combination modes can be realized according to the actual conditions on site, so that wide coal types and high-flexibility combustion can be realized.
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