Boiler structure for burning Zhundong coal

Abstract

The utility model relates to the technical field of pulverized coal boilers, in particular to a boiler structure for burning Zhundong coal, which can avoid slag bonding and ash deposition and ensure normal and stable operation of the boiler, and comprises a hearth, a horizontal flue and a tail shaft flue, a high-temperature superheater is arranged in the horizontal flue, the hearth is provided with combustors, and the combustors are arranged at four corners of the hearth. The combustors are primary air combustors and are provided with four layers, an electric swing plate capable of swinging up and down is arranged in each primary air combustor, a platen superheater is arranged at the top of the hearth and an inlet of the horizontal flue, and the distance L2 between the primary air combustor on the uppermost layer and the platen superheater is larger than or equal to 20 m. The distance L1 between the primary air combustor on the lowermost layer and the inflection point position of the lower portion of the hearth is larger than or equal to 4 m, a middle ignition layer nozzle is arranged between the primary air combustors on the two middle layers, secondary air nozzles are arranged beside the primary air combustors, and soot blowers are arranged in the hearth at intervals.

Description

Technical Field

[0001] The utility model relates to the technical field of pulverized coal boilers, in particular to a boiler structure burning Zhundong coal. Background Art

[0002] The Zhundong coalfield in Xinjiang is a large-scale coalfield in my country, with a predicted reserve of 390 billion tons. The Zhundong mining area is rich in coal resources, with a large coal content per unit area, a relatively simple coal seam structure, shallow burial, and good coal quality. However, the coal has the characteristics of high moisture content, low ash melting point, and high iron and alkali metal content in the ash. After burning Zhundong coal in a boiler that was not designed for Zhundong coal, it was found that the coal has serious slagging and contamination characteristics, which easily causes a series of problems such as slagging in the boiler furnace and ash on the heating surface. Summary of the invention

[0003] In order to solve the problems that burning Zhundong coal in existing boilers easily causes slagging in the furnace and dust accumulation on the heating surface, the utility model provides a boiler structure burning Zhundong coal, which can avoid slagging and dust accumulation and ensure the normal and stable operation of the boiler.

[0004] The technical solution is as follows: a boiler structure burning Zhundong coal comprises a furnace, a horizontal flue and a tail vertical shaft flue, wherein a burner is arranged in the furnace, and the burner is characterized in that the burners are arranged at the four corners of the furnace, the burners are primary air burners and are arranged in four layers, each of the primary air burners is provided with an electric swing plate which can swing up and down, a screen type superheater is arranged at the top of the furnace and the entrance of the horizontal flue, the distance L2 between the primary air burner of the uppermost layer and the screen type superheater is ≥20m, the distance L1 between the primary air burner of the lowermost layer and the inflection point of the lower part of the furnace is ≥4m, an intermediate ignition layer nozzle is arranged between the middle two layers of the primary air burners, a secondary air nozzle is arranged next to the primary air burner, and soot blowers are arranged at intervals in the furnace.

[0005] It is further characterized in that the secondary air nozzles are arranged above and below each of the primary air burners;

[0006] The soot blower is a fixed rotating steam soot blower;

[0007] The high temperature superheater comprises a front hot section and a rear cold section;

[0008] The tail shaft flue is provided with a low-temperature superheater, a light-tube economizer, a denitrification system, and an air preheater in sequence;

[0009] The pitch between the tube sheets of the high-temperature superheater and the tube sheets of the low-temperature superheater is greater than 200 mm;

[0010] A long telescopic soot blower is provided between the high-temperature superheater and the low-temperature superheater;

[0011] The air preheater is a rotary air preheater.

[0012] After the utility model is adopted, the distance between the uppermost primary air burner and the screen superheater is not less than 20m, so that the flue gas temperature can be reduced to a sufficiently low level before entering the horizontal section, avoiding slagging and contamination in the dense tube bundle area, and at the same time having sufficient flue gas residence time to ensure that the fuel can be fully burned. The distance between the uppermost primary air burner and the lower inflection point of the furnace is not less than 4m, ensuring that the carbon content of the large slag does not exceed the design value, and an electric swing plate that can swing up and down is provided in the primary air burner, which can adjust the position of the flame center in the furnace, thereby increasing the temperature of the furnace outlet when the boiler is running at low load. The primary air burners are arranged in groups with a large spacing to ensure that the airflow has sufficient rigidity during operation, the flame is not easy to deflect and brush the wall, and the heat load of the burner wall is also reduced, which can effectively prevent coking in the burner area. The presence of the soot blower can effectively clean the furnace to prevent slagging in the furnace area, thereby ensuring the normal and stable operation of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the utility model;

[0014] Figure 2 This is a schematic diagram of the primary air burner layout. DETAILED DESCRIPTION

[0015] See Figure 1 , Figure 2As shown, a boiler structure burning Zhundong coal comprises a furnace 1, a horizontal flue 2, and a tail shaft flue 3. Burners are arranged at the four corners of the furnace 1. The burners are primary air burners 4 and are arranged in four layers. The upper two layers and the lower two layers at the same angular position form two groups, each of which is provided with an electric swing plate that can swing up and down. Each group is provided with an electric actuator for controlling the angle of the electric swing plate inside the primary air burner 4 during operation. A total of eight electric actuators are arranged at the four corners. The mechanism is a screen superheater 5 arranged at the top of the furnace 1 and the entrance of the horizontal flue 2. The distance L2 between the top primary air burner 4 and the screen superheater 5 is ≥20m, so that the flue gas temperature can be reduced to a sufficiently low level before entering the horizontal flue, avoiding slagging and contamination in the dense tube bundle area, and at the same time, there is enough flue gas residence time to ensure that the fuel can be fully burned; the distance L1 between the bottom primary air burner 4 and the inflection point position of the lower part of the furnace 1 is ≥4m, ensuring that the carbon content of the large slag does not exceed the design value. Sufficient L1 and L2 create favorable conditions for the boiler efficiency to achieve the expected goal. Although a larger L2 value can achieve the purpose of obtaining sufficient flue gas residence time and a lower furnace outlet temperature, it makes it difficult to achieve the rated parameters when the boiler is under low load conditions. It is possible that the main steam temperature cannot reach the design value. The electric swing plate in the primary air burner 4 can swing up and down during operation to solve this problem well. By swinging the nozzle, the position of the flame center in the furnace can be adjusted, thereby increasing the furnace outlet temperature when the boiler is under low load.

[0016] The distance L4 between the two middle layers of primary air burners 4 is as large as possible, and the middle ignition layer nozzle 13 can be set in the middle position, which is put into operation only when ignited. When the boiler is operating normally, it is not put into operation and only needs cooling air, thereby forming a larger transition zone, dividing the entire group of burners into two groups, the height-to-width ratio of a single group of burners is appropriate, ensuring that the airflow has sufficient rigidity during operation, and the flame is not easy to deflect and brush the wall. The distance L3 between the adjacent two layers of primary air burners 4 is pulled apart, the burner height is high enough, and the heat load on the burner wall is also reduced. The above measures are very beneficial for preventing coking in the burner area.

[0017] Secondary air nozzles 6 are provided above and below each primary air burner 4 .

[0018] A plurality of layers of fixed rotary steam soot blowers 7 are arranged at intervals throughout the furnace area, which can effectively clean the furnace 1 and prevent slagging in the furnace area.

[0019] Since the boiler burning Zhundong coal has a large cross-section and a high height, the flue gas temperature at the furnace outlet is lower than that of the boiler burning ordinary coal. In order to ensure the main steam temperature, the superheater system needs to arrange more superheaters. Considering the characteristics of Zhundong coal slagging and contamination, a large pitch design (S>200mm) must be adopted between each superheater tube segment. In this application, the superheater system is arranged in the horizontal flue and the tail shaft flue, and the screen superheater 5, the high-temperature superheater 8, and the low-temperature superheater 9 are arranged from front to back. The high-temperature superheater 8, which was originally arranged in the same plane, is changed to a front and rear two-stage arrangement, that is, including the front hot section and the rear cold section, which can ensure that the pitch is pulled apart. The pitch of the low-temperature superheater 9 is also pulled apart, and the number of lateral slices is reduced. In order to ensure the mass flow rate, the number of tube circles of the single-piece superheater is increased. Several long telescopic soot blowers are arranged between each group of superheaters.

[0020] A group of bare tube economizers 10 are arranged after the low-temperature superheater 9 to ensure the drum inlet water temperature and adjust the denitrification smoke temperature window (the denitrification smoke temperature is maintained between 360°C and 380°C).

[0021] The denitration system is arranged between the light tube economizer 10 and the air preheater 11. After the flue gas passes through the denitration system, the final discharge of the boiler meets the requirements of relevant national laws and regulations.

[0022] The air preheater 11 is a rotary air preheater, which can realize online high-pressure water cleaning, and is very effective in removing ammonium bisulfate crystals formed on the surface of the heated original part due to denitrification.

[0023] In the figure, 12 is a catalyst.

Claims

1. A boiler structure burning Zhundong coal, comprising a furnace, a horizontal flue, and a tail shaft flue, wherein a burner is arranged in the furnace, and a high-temperature superheater is arranged in the horizontal flue, characterized in that: The burners are arranged at the four corners of the furnace, and the burners are primary air burners and are arranged in four layers. Each primary air burner is arranged with an electric swing plate which can swing up and down. Screen superheaters are arranged at the top of the furnace and the entrance of the horizontal flue. The distance L2 between the primary air burner of the uppermost layer and the screen superheater is ≥20m, and the distance L1 between the primary air burner of the lowermost layer and the inflection point of the lower part of the furnace is ≥4m. An intermediate ignition layer nozzle is arranged between the primary air burners of the middle two layers, a secondary air nozzle is arranged beside the primary air burner, and soot blowers are arranged at intervals in the furnace.

2. A boiler structure burning Zhundong coal according to claim 1, characterized in that: The secondary air nozzles are arranged above and below each of the primary air burners.

3. The boiler structure burning Zhundong coal according to claim 1 is characterized in that: The soot blower is a fixed rotary steam soot blower.

4. The boiler structure burning Zhundong coal according to claim 1 is characterized in that: The high temperature superheater comprises a front hot section and a rear cold section.

5. The boiler structure burning Zhundong coal according to claim 1, characterized in that: A low-temperature superheater, a light-tube economizer, a denitrification system, and an air preheater are sequentially arranged in the tail shaft flue.

6. A boiler structure burning Zhundong coal according to claim 5, characterized in that: The pitch between the tube sheets of the high-temperature superheater and the tube sheets of the low-temperature superheater is greater than 200 mm.

7. A boiler structure burning Zhundong coal according to claim 6, characterized in that: A long telescopic soot blower is arranged between the high-temperature superheater and the low-temperature superheater.

8. The boiler structure burning Zhundong coal according to claim 5, characterized in that: The air preheater is a rotary air preheater.

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