CN113883501B

CN113883501B - Boiler peak shaving method of W flame boiler for flexibly shaving peak by double-layer coal bunker

Info

Publication number: CN113883501B
Application number: CN202111282642.1A
Authority: CN
Inventors: 杜贺; 李争起; 张鸣镝; 郑玉; 陈智超; 宋健
Original assignee: Hunan Datang Energy Saving Science And Technology Co ltd; Harbin Institute of Technology
Current assignee: Hunan Datang Energy Saving Science And Technology Co ltd; Harbin Institute of Technology
Priority date: 2021-11-01
Filing date: 2021-11-01
Publication date: 2022-09-16
Anticipated expiration: 2041-11-01
Also published as: CN113883501A

Abstract

The invention relates to a boiler peak regulation method of a W flame boiler with a double-layer coal bunker for flexible peak regulation, in particular to the W flame boiler with the flexible peak regulation and the boiler peak regulation method, aiming at solving the problems that the few boilers of the existing W flame boilers can realize 30 percent ultralow load stable combustion, the peak regulation technology is difficult to realize and the current flexible peak regulation and deep peak regulation requirements of the power environment are difficult to meet, and the boiler peak regulation method comprises a W flame boiler combustion system and a coal bunker system, wherein the W flame boiler combustion system comprises a hearth and two groups of double-cyclone barrel combustors, and the coal bunker system comprises a coal distribution bunker and the double-layer coal bunker; the method is realized according to the following steps: the method comprises the following steps: preparation work: the main coal bunker and the coal blending bunker are used for storing inferior anthracite and lean coal in daily life, and the inner-layer coal blending bunker is used for storing high-quality bituminous coal in daily life; step two: and (3) combustion work: starting the W flame boiler to work; step three: peak regulation work: and setting peak shaving work according to requirements. The invention is used in the field of boiler combustion.

Description

Boiler peak shaving method of W flame boiler for flexibly shaving peak by double-layer coal bunker

Technical Field

The invention relates to a W flame boiler with flexible peak regulation and a boiler peak regulation method, in particular to a boiler peak regulation method of a W flame boiler with flexible peak regulation by double-layer coal bunkers, belonging to the field of boilers.

Background

In recent years, with the development of clean and renewable energy sources such as wind power, hydropower and the like, the power system in China has changed greatly. The power generation capacity of renewable energy sources is increasing in proportion to the power grid. However, the renewable energy power generation mode has the limitation of unstable output, which brings great challenges to the regulation capability of the power system. The problem of serious wind abandon occurs in part of regions, and consumption becomes a key factor for restricting the development of new energy resources such as wind power and the like. Therefore, in order to adapt to the high-speed development of renewable energy sources, improve the consumption capacity of a power system on the renewable energy sources, ensure the safe and stable operation of the power system, and flexibly modify a coal-electric machine set, the method is imperative.

The W-flame boiler is a power station boiler specially designed for burning low-volatile and difficult-to-burn coal such as lean coal, anthracite and the like. Because the coal used for power in China is varied in types and has coal quality deviation. Therefore, W flame boilers are widely applied in China, and by far, the number of W flame boilers in active service and under construction in China reaches about 100, and the total installed capacity reaches 41000 MW. 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, compared with other coal-fired utility boilers, the W flame boiler has the difficulties in flexible peak regulation and is heavy. At present, the minimum oil-free stable combustion load of an active W flame boiler is about 50 percent of the rated load. Only few boilers can realize 30% ultralow load stable combustion, and the peak regulation technology is difficult to meet the requirements of flexible peak regulation and deep peak regulation in the current power environment. It is therefore necessary to develop techniques and equipment that can efficiently achieve flexible peak shaving in W-fired boilers.

Disclosure of Invention

The invention aims to solve the problems that 30% ultralow load stable combustion can be realized by few boilers of the existing W flame boiler, the peak regulation technology is difficult to meet the requirements of flexible peak regulation and deep peak regulation in the current power environment, and further provides a boiler peak regulation method of the W flame boiler, which is used for realizing flexible peak regulation by double-layer coal bunkers.

The technical problem is solved by the following scheme:

the W flame boiler combustion system comprises a hearth and two groups of double-cyclone-cylinder combustors, and the coal bunker system comprises a coal blending bunker and a double-layer coal bunker; one group of double-cyclone cylinder burners are arranged on a front arch of the hearth, the other group of double-cyclone cylinder burners are arranged on a rear arch of the hearth, an outlet of an exhaust pipeline on each group of double-cyclone cylinder burners is communicated with a lower hearth of the hearth, a double-layer coal bunker system is communicated with each group of double-cyclone cylinder burners, and a coal blending bunker is communicated with the exhaust pipeline on each group of double-cyclone cylinder burners.

The method is realized according to the following steps:

the method comprises the following steps: preparation work: the main coal bunker and the coal blending bunker are used for storing low-quality anthracite and lean coal in a daily mode, the inner layer coal blending bunker is used for storing high-quality bituminous coal in a daily mode, in the step one, the coal storage amount of the inner layer coal blending bunker is 0.8-1 time of that of the inner layer coal blending bunker and the main coal bunker, and the coal storage amount of the coal blending bunker is 0.2-0.5 time of that of the inner layer coal blending bunker and the main coal bunker;

step two: and (3) combustion work: starting a W flame boiler to work, adjusting the coal blending amount in a main coal bin and an internal coal blending bin of a coal amount adjusting valve, feeding the coal into a blender through a coal conveying pipeline, fully stirring the coal by the blender, finally feeding the blended coal into a double-cyclone barrel burner of the boiler through the coal conveying pipeline, and enabling coal dust airflow of the double-cyclone barrel burner to form thick and thin coal dust airflow through the thick and thin separation action of a cyclone barrel, wherein the thick coal dust airflow is directly sprayed into a hearth through a burner nozzle, and the thin coal dust airflow is sprayed into the hearth through a ventilation pipeline to participate in a combustion reaction in the hearth;

step three: peak regulation work: the peak regulation work is set according to the requirement, the peak regulation work of the W flame boiler is carried out by controlling the quality and the type of the pulverized coal entering the hearth of the coal blending bin and the double-layer coal bin, and the peak regulation work of the W flame boiler is further achieved.

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

1. the invention can realize that the same boiler can simultaneously burn anthracite, lean coal and bituminous coal. Currently, domestic W flame boilers in active service only have a common coal bunker system, coal used for daily combustion is generally poor anthracite with a dry ash-free base volatile matter content of less than or equal to 9% or lean coal (the dry ash-free base volatile matter content is 9% -19%, the Vdaf content of the coal is generally about 10%, the ash content is high, the structure is compact, ignition and burnout are difficult, the ignition temperature of pulverized coal airflow can generally reach 900 ℃ or even higher, for burning the anthracite and the lean coal, the traditional W flame boilers generally adopt a dense-dilute separation combustion mode to reduce primary air speed, thereby improving the primary air pulverized coal concentration, shortening the ignition distance of the pulverized coal airflow, and ensuring timely ignition of the pulverized coal airflow When the boiler is at above 60% rated load, the firing temperature of the pulverized coal airflow can be greatly reduced to 600 ℃ or even lower due to the higher Vdaf content of the coal, and the firing distance of the pulverized coal airflow is obviously shortened. When the same combustion method as that of anthracite is adopted, a high-temperature area formed by firing of pulverized coal airflow is close to a burner nozzle, so that the burner nozzle is easy to burn and deform, and a high primary air speed is required. Meanwhile, due to the fact that ignition is advanced and the required burnout distance is shortened, after bituminous coal is burnt, the main burning zone of pulverized coal is completely concentrated in the lower hearth area, the temperature of the lower hearth can reach 1500 ℃ or even higher, and the heating surface is extremely easy to be over-heated. And the ash content carried in the coal dust is heated to a molten state at the high temperature of 1500 ℃, so that the ash content is easy to adhere to a burning control belt of a furnace wall to cause a serious slag bonding problem, and the safe operation of the boiler is threatened. Therefore, the conventional W-flame boiler with only a common coal bunker system can only be suitable for burning low-quality coal such as anthracite, lean coal and the like. The invention stores high-quality bituminous coal by arranging the double-layer coal bunker system, flexibly changes the quality of coal entering the boiler according to the operation load of the boiler, and can realize the simultaneous combustion of the anthracite, the lean coal and the bituminous coal by the same boiler. The coal bunker system of the boiler comprises a double-layer coal bunker system and a common coal bunker system, wherein the double-layer coal bunker system is connected with a double-cyclone cylinder burner at the arch part of the boiler through a coal conveying pipeline, and the common coal bunker system is connected with an exhaust pipeline through a coal conveying pipeline. And a coal quantity regulating valve is arranged on the exhaust gas pipeline. The main coal bunker and the coal blending bunker routinely store poor anthracite or lean coal with Vdaf of about 5-15%, and the inner coal blending bunker routinely stores high-quality bituminous coal with Vdaf of 25-40%. When the boiler operates at a rated load of more than 75 percent, due to the fact that the coal amount fed into the boiler is relatively high, the pulverized coal is burnt in a hearth to release enough heat, and the temperature of the hearth is improved. The pulverized coal airflow can still be timely ignited and stably combusted when anthracite and lean coal are combusted, and stable operation of the boiler is realized. At this time, the inner coal blending bunker and the coal blending bunker are closed, the coal quantity regulating valve 10 is opened, and the coal quality of the coal fed into the furnace is completely supplied by the main coal bunker. When the boiler is in 40-75% of normal low load, because the coal amount fed into the boiler is reduced, the temperature of a hearth is reduced, at the moment, the poor-quality anthracite and lean coal in the main coal bunker and the high-quality bituminous coal in the inner coal bunker are mixed according to the load level to form mixed coal with 16-25% of volatile components, and the stable operation of the boiler can be still ensured while the combustion mode of the boiler is not changed. When the boiler is in 20-40% rated load deep peak shaving, compared with the conventional load, the coal feeding amount of the boiler is greatly reduced, the temperature of a hearth is greatly reduced, and the burning conditions of anthracite and lean coal cannot be met. Meanwhile, in order to ensure the normal conveying of the pulverized coal, the primary air speed of the boiler is still kept at a high level, and the burning requirement of the bituminous coal is completely met. Thus, under this load condition, the coal quality in the boiler crown burner is supplied entirely by the high quality bituminous coal in the inner bunker. After being fed into the hearth, high-quality bituminous coal can still be ignited in time at a relatively low hearth temperature and can be sufficiently combusted in the lower hearth to release enough heat, so that the stable operation of the boiler is ensured. At the moment, the coal quantity regulating valve on the exhaust gas pipeline is closed, the inferior power coal stored in the coal blending bin is supplied to the high-temperature main combustion area of the lower hearth through the exhaust gas pipeline, the combustion proportion of the inferior power coal is properly improved on the premise of ensuring the stable combustion characteristic of the boiler, and the economic benefit of the operation of the boiler is improved. In conclusion, the invention flexibly adjusts the burning of the anthracite and the bituminous coal according to the load of the boiler, and the coal quality put into the boiler is changed in time according to the actual operation condition of the boiler. The boiler can realize the simultaneous combustion of anthracite, lean coal and bituminous coal by the same boiler while ensuring the stable operation of the boiler under various load states, and the adaptability to coal types is greatly improved.

2. The invention can simultaneously realize the stable operation of the W flame boiler with full load, normal low load and 20 to 40 percent ultralow load

Since the conventional W-flame boiler is designed to burn low-quality anthracite or lean coal. When the boiler is in normal low-load or full-load operation, the coal amount put into the boiler is large. The coal powder is burnt in the hearth to release a large amount of heat, so that the temperature of the hearth can be maintained to be above 1000 ℃, and the stable combustion of anthracite and lean coal can be ensured. However, when the boiler load is reduced to a lower level, because the fuel quantity fed into the boiler is greatly reduced, and the primary air speed is reduced, the burnout distance of the pulverized coal airflow in the lower hearth is shortened, pulverized coal particles cannot be sufficiently combusted in the hearth, so that the temperature in the lower hearth is greatly reduced, and the pulverized coal airflow cannot be stably combusted and even can extinguish fire. At present, the minimum oil-free stable combustion load of an existing W flame boiler is only about 50%, and the stable combustion of 20-40% of ultralow load and even ultralow load cannot be realized. Therefore, the traditional W flame boiler can not realize the stable operation of full load, normal low load and 20-40% ultra-low load of the W flame boiler simultaneously only through operation adjustment. The invention realizes the stable operation of the same boiler under the conditions of full load, normal low load and 20 to 40 percent ultralow load by arranging the external coal blending system and flexibly adjusting the coal quality entering the boiler. When the boiler is operated at normal load and full load above 75%, the coal as fired is completely supplied by the main coal bunker, and the coal as fired is about 10% of anthracite and lean coal. Under the load condition, the boiler fuel supply is large, the pulverized coal burns in the hearth to release more heat, the temperature in the hearth can be maintained above 1000 ℃, and the pulverized coal airflow is guaranteed to catch fire and stably burn in time after being sprayed into the hearth, so that the stable burning of the boiler is realized. When the boiler is in 40-75% normal low-load operation, all coal mills and burners of the W flame boiler are still put into use, but because the amount of coal entering the boiler is reduced, the temperature of a hearth is reduced, and the temperature conditions in the boiler can not meet the requirements of ignition and stable combustion of pulverized coal airflow when only anthracite and lean coal are combusted. At the moment, the main coal bunker and the inner-layer coal blending bunker are put into use at the same time. The low-quality power coal in the main coal bunker and the high-quality bituminous coal in the inner-layer coal blending bunker are reasonably proportioned according to the requirement of boiler load, so that the Vdaf content of the coal quality entering the boiler reaches the level of 10-20%, the ignition point of pulverized coal airflow is reduced to about 800 ℃, the burnout distance required by pulverized coal combustion is shortened, more heat is released in a lower hearth, the temperature level in the hearth is improved, and the timely ignition and stable combustion of the pulverized coal airflow are ensured. When the boiler is in a deep peak shaving state of 20-40%, the coal grinding machines and the burners of the boiler are all put into use due to the fact that the fuel quantity entering the boiler is greatly reduced, the coal powder concentration of primary air of the burners is reduced to an extremely low level, and the firing conditions cannot be met. At this time, the power plant usually stops 1-2 coal mills to increase the pulverized coal concentration of the primary air of the operating combustor. As the amount of coal powder entering a boiler is greatly reduced, the temperature of a hearth is greatly reduced, and meanwhile, in order to ensure that the wind speed of primary air of the powder feeding capacity is still kept about 15m/s, when 10-20% of lean coal is used by a boiler, the timely ignition and stable combustion of coal powder airflow cannot be effectively ensured. At the moment, the main coal bunker is stopped, and the boiler mainly burns high-quality bituminous coal with the Vdaf content of more than 20% in the inner-layer coal blending bunker. Meanwhile, a small amount of low-quality coal is directly fed into the high-temperature main combustion area of the lower hearth through an exhaust gas pipeline. The ignition point of the pulverized coal airflow can be greatly reduced to about 700 ℃ under the condition of the air-coal ratio of ultra-low load, and the pulverized coal airflow can not cause damage to a burner nozzle after being ignited under the condition of reducing the powder feeding amount. Meanwhile, the flow distance and the time required by the pulverized coal airflow after being burnt out are greatly shortened, the pulverized coal airflow can be fully combusted in the lower hearth, more heat is released, the overall temperature level of the lower hearth area is improved, and the pulverized coal airflow is ensured to catch fire and stably combust in time so as to ensure the stable operation of the boiler. Therefore, the invention can realize the stable operation of the same boiler under the conditions of full load, normal low load and 20-40% ultra-low load through operation adjustment.

3. The invention can realize the flexible peak regulation of the boiler

In recent years, in order to solve the problem of deep peak regulation of the boiler, various measures for improving the low-load stable combustion capacity of the boiler are provided for the thermal power plant. The most effective measure at present is to store a certain amount of high-quality bituminous coal, and change the coal quality for boiler combustion from low-quality anthracite coal into high-quality bituminous coal which is easy to ignite and stably combust under the conditions of low load and ultralow load of the boiler. The measure can effectively improve the low-load stable combustion capacity of the boiler and realize deep peak regulation. But can be effectively developed only on the premise of predicting the requirement of deep peak regulation of the boiler. And the coal quality of the boiler coal burning system is changed and the operation scheduling of the coal yard needs a certain transition time, so the flexible peak shaving capability of the measure is very limited, and the flexible peak shaving requirement of the future thermal power plant cannot be met. In the invention, a certain amount of high-quality bituminous coal is stored in a power plant for a long time by constructing parallel inferior and high-quality coal supply systems outside the boiler. When the boiler has the requirement of deep peak regulation, the coal quantity regulating valves of the main coal bunker and the inner-layer coal blending bunker are adjusted in time, and the coal quality characteristics of the boiler entering the boiler can be effectively changed by changing the coal quantity ratio of the inferior coal and the high-quality coal, so that the boiler meets the requirement of low-load stable combustion. When the boiler needs to be adjusted to be operated at full load, the load adjustment of the boiler can be realized while the stable and safe operation of the boiler is ensured by changing the coal amount ratio of the main coal bin, the inner-layer coal blending bin and the coal blending bin and improving the ratio of anthracite to leaner coal in the coal as fired. According to the invention, only the coal quantity regulating valve of the coal bunker needs to be regulated during peak regulation, and no additional operation scheduling is needed, so that the operation is convenient and fast, and the flexible peak regulation of the boiler can be realized.

Drawings

Fig. 1 is a schematic view of the overall structure of the present application.

Fig. 2 is a schematic view of the connection between the double cyclone burner 8 and the hearth 7.

Detailed Description

The first embodiment is as follows: the embodiment is described with reference to fig. 1 and 2, the W-flame boiler with the double-layer coal bunker for flexible peak shaving comprises a W-flame boiler combustion system and a coal bunker system, wherein the W-flame boiler combustion system comprises a hearth 7 and two groups of double-cyclone-cylinder combustors 8, and the coal bunker system comprises a coal blending bunker 1-2 and the double-layer coal bunker; one group of double-cyclone cylinder burners 8 are arranged on a front arch of the hearth 7, the other group of double-cyclone cylinder burners 8 are arranged on a rear arch of the hearth 7, an outlet of a waste gas pipeline 9 on each group of double-cyclone cylinder burners 8 is communicated with a lower hearth of the hearth 7, a double-layer coal bunker system is communicated with each group of double-cyclone cylinder burners 8, and the coal distribution bunker 1-2 is communicated with the waste gas pipeline 9 on each group of double-cyclone cylinder burners 8.

The second embodiment is as follows: the embodiment is described with reference to fig. 1 and 2, and the double-layer coal bunker of the embodiment is a W-flame boiler for flexible peak regulation, and comprises two main coal bunkers 1, two inner-layer coal blending bunkers 2 and two blenders 4; each inner-layer coal blending bin 2 is arranged in one main coal bin 1, each inner-layer coal blending bin 2 and the outer main coal bin 1 are communicated with one blender 4, and each blender 4 is communicated with one group of double-cyclone-cylinder combustors 8. The inferior coal output from the main coal bunker 1 and the high-quality coal output from the inner-layer coal blending bunker 2 are uniformly mixed by the blender 4, input into the coal mill 5, input into the double-cyclone burner 8 through the coal conveying pipeline 6 and finally supplied to the hearth for combustion. Other components and connection modes are the same as those of the first embodiment.

Vdaf output by the main coal bin 1 and the coal blending bins 1-2 is about 5-15% of low-quality anthracite or lean coal, and Vdaf output by the inner coal blending bin 2 is about 25-40% of high-quality coal.

The third concrete implementation mode: the embodiment is described with reference to fig. 1 and 2, and the W-flame boiler with double-layer coal bunker for flexible peak shaving further comprises a plurality of coal mills 5, wherein one coal mill 5 is arranged on a coal conveying pipeline 6 between each blender 4 and a double-cyclone cylinder burner 8, and one coal mill 5 is arranged on a coal conveying pipeline 6 between each coal blending bunker 1-2 and an exhaust gas pipeline 9. Other components and connection modes are the same as those of the second embodiment.

The fourth concrete implementation mode: referring to fig. 1 and 2, the embodiment is described, the double-deck bunker W-flame boiler for peak shaving in the embodiment further includes a plurality of first coal quantity adjusting valves 3, one first coal quantity adjusting valve 3 is installed on a pipe between each main bunker 1 and the blender 4, and one first coal quantity adjusting valve 3 is installed on a pipe between each inner-deck coal blending bunker 2 and the blender 4. Other components and connection modes are the same as those of the third embodiment.

The fifth concrete implementation mode: referring to fig. 1 and 2, the embodiment is described, in which the double-deck bunker W-flame boiler performs peak shaving flexibly, the outlet end of each exhaust duct 9 of the double-cyclone burner 8 on the front arch of the furnace 7 is located at the upper position of the front wall of the furnace 7, and the outlet end of each exhaust duct 9 of the double-cyclone burner 8 on the rear arch of the furnace 7 is located at the upper position of the rear wall of the furnace 7. Other components and connection modes are the same as those of the first embodiment.

The sixth specific implementation mode: the embodiment is described with reference to fig. 1 and 2, and the W-flame boiler with the double-layer coal bunker for flexible peak regulation of the embodiment further comprises a second coal quantity regulating valve 10; each exhaust gas pipeline 9 is provided with a second coal quantity regulating valve 10. Other components and connection modes are the same as those of the first embodiment.

The seventh embodiment: the boiler peak shaving method of the W flame boiler with the double-layer coal bunker for flexible peak shaving is realized by the following steps:

the method comprises the following steps: preparation work: the main coal bunker 1 and the coal blending bunker 1-2 are used for daily storage of low-quality anthracite and lean coal, the inner-layer coal blending bunker 2 is used for daily storage of high-quality bituminous coal, in the step one, the coal storage amount in the inner-layer coal blending bunker 2 is 0.8-1 time of the coal storage amount in the inner-layer coal blending bunker 2 and the main coal bunker 1, and the coal storage amount in the coal blending bunker 1-2 is 0.2-0.5 time of the coal storage amount in the inner-layer coal blending bunker 2 and the main coal bunker 1;

step two: and (3) combustion work: starting a W flame boiler to work, adjusting a first coal quantity adjusting valve 3 to control the coal blending quantity in a main coal bin 1 and an internal coal blending bin 2, enabling the coal to enter a blender 4 through a coal conveying pipeline 6, fully stirring the coal by the blender 4, finally feeding the blended coal into a double-cyclone barrel burner 8 of the boiler through the coal conveying pipeline 6, and enabling coal dust airflow of the double-cyclone barrel burner 8 to form thick and thin coal dust airflow through the thick and thin separation action of a cyclone barrel, wherein the thick coal dust airflow is directly sprayed into a hearth through a burner nozzle, and the thin coal dust airflow is sprayed into the hearth through a ventilation pipeline to participate in a combustion reaction in the hearth;

step three: peak regulation work: the peak regulation work is set according to the requirement, the peak regulation work of the W flame boiler is carried out by controlling the quality and the type of the pulverized coal which enters the hearth 7 of the coal blending bins 1-2 and the double-layer coal bins, and the peak regulation work of the W flame boiler is further achieved.

The Vdaf stored in the main coal bunker 1 and the coal blending bunker 1-2 is 5-15% of inferior anthracite or lean coal, and the Vdaf output in the inner coal blending bunker 2 is 25-40% of high-quality coal.

The specific implementation mode eight: the peak regulation operation in the third step is that when the working load of the boiler needs to be more than 75% of the rated peak regulation operation, the inner coal blending bunker 2 and the coal blending bunkers 1-2 stop working, the second coal quantity regulating valve 10 is opened, only the main coal bunker 1 supplies pulverized coal, and the pulverized coal supplied by the main coal bunker 1 in the hearth 7 is combusted. The other components and the connection mode are the same as those of the seventh embodiment.

The specific implementation method nine: the peak regulation operation in the third step is that when the working load of the boiler needs to be more than 40% and less than or equal to 75% of the rated peak regulation operation, the main coal bunker 1 and the inner-layer coal blending bunker 2 are both opened, the second coal quantity regulating valve 10 is opened, the coal blending bunkers 1-2 stop operating, and the pulverized coal supplied by the main coal bunker 1 and the inner-layer coal blending bunker 2 in the hearth 7 is combusted. The other components and the connection mode are the same as those of the seventh embodiment.

The detailed implementation mode is ten: the peak regulation in the third step is that when the boiler needs to work with the load of the boiler more than or equal to 20% and less than or equal to 40% of rated peak regulation, the inner coal blending bunker 2 and the coal blending bunkers 1-2 are both opened, the second coal quantity regulating valve 10 is closed, the coal blending bunkers 1-2 work to provide coal powder to the exhaust gas pipeline 9 for coal supply, and the coal powder provided by the inner coal blending bunkers 2 and 1-2 in the hearth 7 is combusted. The other components and the connection mode are the same as those of the seventh embodiment.

In the embodiment, the exhaust gas pipeline 9 is independently discharged from the arch double-cyclone cylinder combustor 8, and according to the peak regulation requirement of the boiler, the inferior anthracite or lean coal in the coal blending bin 1-2 is directly fed into a high-temperature main combustion area of a lower hearth of the boiler through the exhaust gas pipeline, so that more cheap inferior power coal is combusted while the stable combustion performance of the boiler is ensured, and the economic benefit is improved.

Principle of operation

Example (b): the invention has been applied to a 300MW FW type W flame boiler in a power plant. 12 groups of 24 double-cyclone-cylinder thick and thin pulverized coal burners are symmetrically arranged on the front wall and the rear wall of the boiler. The boiler was equipped with A, B, C, D4 coal mills, each supplying 2 sets of burners. B, D two coal mills of the rear boiler adopting the invention are both provided with double-layer coal bunker systems. High-quality bituminous coal with coal dry ashless volatile components of 10-15% and dry ashless volatile components of 20-25% is stored in the inner coal blending bunker. Before the invention is adopted, 24 burners on the front wall and the rear wall of the boiler are all put into operation and can keep stable operation under the full load condition. However, when the boiler load is reduced to 175MWe, namely 50% BMCR load, A, C two mills of the boiler are stopped, only B, D two coal mills are put into operation, and the actual operation shows that 12 traditional combustors corresponding to the two mills have the phenomena of difficult ignition, unstable combustion and even fire extinguishing to different degrees, and the ignition distance of the combustors can reach more than 2 m. The peak regulation capacity is only about 50%. And because the coal quality of the daily combustion of the boiler changes, the problems of overheating of a reheater and a wall and slag bonding on the side of a wing wall often occur in the running process of the boiler. After the invention is adopted, when only B, D mills are put into operation, the ignition points of the burners are all about 1.2m by adjusting the coal blending quantity of the basic coal bunker and the reserve coal bunker, the ignition point temperature of the pulverized coal airflow is reduced to about 600 ℃ through test measurement, the pulverized coal airflow is ignited in time, and the stable combustion characteristic is good. When the boiler load is reduced to 20%, the 12 burners can still be stably put into operation by adjusting the ratio of high-quality coal to low-quality coal. And the problems of reheater and wall temperature overtemperature of the boiler disappear and the problem of side slagging of the wing wall is reduced.

Claims

1. The boiler peak shaving method of the W flame boiler for carrying out flexible peak shaving by the double-layer coal bunker; the W-flame boiler combustion system comprises a hearth (7), two groups of double-cyclone-cylinder combustors (8) and a second coal quantity adjusting valve (10), and the coal bunker system comprises a coal blending bunker (1-2) and a double-layer coal bunker; the double-layer coal bunker comprises two main coal bunkers (1), two inner-layer coal blending bunkers (2), two blenders (4) and a plurality of first coal quantity adjusting valves (3); one group of double cyclone cylinder burners (8) is arranged on a front arch of a hearth (7), the other group of double cyclone cylinder burners (8) is arranged on a rear arch of the hearth (7), an outlet of a waste gas pipeline (9) on each group of double cyclone cylinder burners (8) is communicated with a lower hearth of the hearth (7), a double-layer coal bunker is communicated with each group of double cyclone cylinder burners (8), a coal distribution bunker (1-2) is communicated with the waste gas pipeline (9) on each group of double cyclone cylinder burners (8), each inner-layer coal distribution bunker (2) is arranged in one main coal bunker (1), each inner-layer coal distribution bunker (2) and an outer main coal bunker (1) are communicated with one blender (4), each blender (4) is communicated with one group of double cyclone cylinder burners (8), a first coal quantity adjusting valve (3) is arranged on a pipeline between each main coal bunker (1) and the blender (4), a first coal quantity adjusting valve (3) is arranged on a pipeline between each inner-layer coal blending bin (2) and the blender (4), a second coal quantity adjusting valve (10) is arranged on each exhaust pipeline (9),

the method is characterized in that: the method is realized according to the following steps:

the method comprises the following steps: preparation work: the main coal bunker (1) and the coal blending bunker (1-2) are used for storing low-quality anthracite and lean coal in a daily mode, the inner layer coal blending bunker (2) is used for storing high-quality bituminous coal in a daily mode, in the step one, the coal storage amount in the inner layer coal blending bunker (2) is 0.8-1 time of that in the inner layer coal blending bunker (2) and the main coal bunker (1), and the coal storage amount in the coal blending bunker (1-2) is 0.2-0.5 time of that in the inner layer coal blending bunker (2) and the main coal bunker (1);

step two: and (3) combustion work: starting a W flame boiler to work, adjusting a first coal quantity adjusting valve (3) to control the coal distribution quantity in a main coal bin (1) and an internal coal distribution bin (2), feeding the coal into a blender (4) through a coal conveying pipeline (6), fully stirring the coal by the blender (4), finally feeding the blended coal into a double-cyclone barrel burner (8) of the boiler through the coal conveying pipeline (6), and forming thick and thin coal powder airflow through the thick-thin separation action of a cyclone barrel by the coal powder airflow of the double-cyclone barrel burner (8), wherein the thick coal powder airflow is directly sprayed into a hearth through a burner nozzle, and the thin coal powder airflow is sprayed into the hearth through an exhaust pipeline to participate in a combustion reaction in the hearth;

step three: peak regulation work: setting peak shaving work according to requirements, controlling the quality and the type of the pulverized coal entering a hearth (7) by the coal blending bins (1-2) and the double-layer coal bins to enable the W flame boiler to carry out the peak shaving work, and further achieving the peak shaving work of the W flame boiler;

the peak regulation work in the third step is that when the work load of the boiler needs to be more than or equal to 20% and less than or equal to 40% of rated peak regulation, the inner coal blending bunker (2) and the coal blending bunker (1-2) are both opened, the second coal quantity regulating valve (10) is closed, the coal blending bunker (1-2) works to provide coal powder for the exhaust gas pipeline (9) for coal supply, and the coal powder provided by the inner coal blending bunker (2) and the coal blending bunker (1-2) in the hearth (7) is combusted.

2. The boiler peak shaving method of the W flame boiler with the double-layer coal bunker capable of realizing the flexible peak shaving according to the claim 1, is characterized in that: the coal blending device also comprises a plurality of coal mills (5), one coal mill (5) is arranged on a coal conveying pipeline (6) between each blender (4) and the double-cyclone cylinder combustor (8), and one coal mill (5) is arranged on a coal conveying pipeline (6) between each coal blending bin (1-2) and the exhaust gas pipeline (9).

3. The boiler peak shaving method of the W flame boiler with the double-layer coal bunker capable of realizing the flexible peak shaving according to the claim 1, is characterized in that: the outlet end of each exhaust pipeline (9) of the double-cyclone barrel burner (8) on the front arch of the hearth (7) is positioned at the upper part of the front wall of the hearth (7), and the outlet end of each exhaust pipeline (9) of the double-cyclone barrel burner (8) on the rear arch of the hearth (7) is positioned at the rear wall of the hearth (7).

4. The boiler peak shaving method of the W flame boiler with the double-layer coal bunker capable of realizing the flexible peak shaving according to the claim 1, is characterized in that: the peak regulation work in the third step is that when the work load of the boiler needs to be more than 75 percent of the rated peak regulation work, the inner coal blending bunker (2) and the coal blending bunkers (1-2) stop working, the second coal quantity regulating valve (10) is opened, only the main coal bunker (1) supplies coal powder, and the coal powder supplied by the main coal bunker (1) in the hearth (7) is combusted.

5. The boiler peak shaving method of the W-flame boiler with the double-layer coal bunker capable of carrying out the peak shaving flexibly according to the claim 1, which is characterized in that: the peak regulation work in the third step is that when the working load of the boiler needs to be more than 40% and less than or equal to 75% of the rated peak regulation work, the main coal bunker (1) and the inner-layer coal distribution bunker (2) are both opened, the second coal quantity regulating valve (10) is opened, the coal distribution bunkers (1-2) stop working, and the pulverized coal supplied by the main coal bunker (1) and the inner-layer coal distribution bunker (2) in the hearth (7) is combusted.