Boiler hot air recirculation device

Abstract

The utility model relates to the technical field of pulverized coal boilers, and discloses a boiler hot air recirculation device which comprises a coal feeder, a coal mill, a burner, a boiler, a primary air pre-heater, a secondary air pre-heater, a primary air fan and an air feeder. The coal feeder conveys coal into the coal mill, and a coarse powder separator is mounted on the coal mill; the coarse powder separator is connected with the combustor through a coal mill outlet pipe, and the combustor is connected with the boiler; the primary air pre-heater is connected with the coal mill through a hot primary air pipeline, and the secondary air pre-heater is connected with the combustor through a hot secondary air pipeline; a primary fan outlet pipe is arranged on the primary fan and connected with the primary air pre-heater, and an air feeder outlet pipe is arranged on the air feeder and connected with the secondary air pre-heater; a hot air recirculation pipe is arranged on the hot secondary air pipeline and connected with the primary fan, and a cold primary air pipeline is arranged on an outlet pipe of the primary fan and connected with the hot primary air pipeline.

Description

Technical Field

[0001] The utility model relates to the technical field of pulverized coal boilers, in particular to a boiler hot air recirculation device. Background Art

[0002] At present, pulverized coal boilers are equipped with pulverized coal burners, which are generally arranged tangentially at the four corners. The pulverizing system is equipped with a pulverizer. The temperature of the gas-powder mixture at the outlet of the pulverizer is normally controlled at 65-90°C. Each time the boiler starts, it is necessary to start the cold furnace heating fan on the air duct entering the pulverizer, and put the air duct heating oil gun into use to increase the primary air temperature entering the pulverizer. In winter, when the temperature is low or high-moisture coal is burned, the outlet temperature of the pulverizer is also difficult to guarantee during normal operation. If the temperature is too low, the drying output of the pulverizer will decrease, it is easy to block the coal, and the air-powder duct will also stick to the pulverized coal, causing the system resistance to increase, which is not conducive to combustion. If it is low load or the coal quality is not good, the ignition stability is also poor. Increasing the air temperature by heating the fan will consume fuel and is not economical. Utility Model Content

[0003] The utility model aims to provide a boiler hot air recirculation device to solve the problem that it is uneconomical to consume fuel by heating a fan to increase the air temperature.

[0004] To achieve the above object, the utility model provides a boiler hot air recirculation device, comprising: a coal feeder, a coal mill, a burner, a boiler, a primary air preheater, a secondary air preheater, a primary fan, and a blower;

[0005] The coal feeder conveys coal into the coal mill, and a coarse powder separator is installed on the coal mill;

[0006] The coarse powder separator and the burner are connected via a coal mill outlet pipe, and the gas-powder mixture separated by the coarse powder separator is transported to the burner via the coal mill outlet pipe, and the burner is connected to the boiler;

[0007] The primary air preheater and the coal mill are connected via a hot primary air duct, and the secondary air preheater and the burner are connected via a hot secondary air duct;

[0008] The primary fan is provided with a primary fan outlet pipe connected to the primary air air preheater, and the blower is provided with a blower outlet pipe connected to the secondary air air preheater;

[0009] The hot secondary air duct is provided with a hot air recirculation pipe connected to the primary air fan, and the primary air fan outlet pipe is provided with a cold primary air duct connected to the hot primary air duct.

[0010] Preferably, in the above-mentioned boiler hot air recirculation device, the primary fan and the air supply fan are connected with an air suction port through a pipeline, and a muffler and a fan inlet damper are provided on the pipeline.

[0011] Preferably, in the above-mentioned boiler hot air recirculation device, a baffle door is provided on the coal mill air inlet pipe, the hot primary air duct is connected to the baffle door, and a hot air damper is provided on the hot primary air duct.

[0012] Preferably, in the above-mentioned boiler hot air recirculation device, the cold primary air duct is connected to one end of the hot primary air duct connected to the baffle door, and a cold air damper is provided on the cold primary air duct.

[0013] Preferably, in the above-mentioned boiler hot air recirculation device, a hot air recirculation air duct butterfly valve and a hot air recirculation air duct regulating valve are provided on the hot air recirculation pipe.

[0014] Therefore, the utility model adopts a boiler hot air recirculation device of the above structure, and introduces the secondary hot air into the primary fan inlet through the hot air recirculation pipe, thereby increasing the air temperature at the primary fan inlet, increasing the primary fan outlet temperature, increasing the air temperature entering the primary air air preheater, and reducing the heating energy consumption of the primary air air preheater, so that the outlet air temperature of the coal mill can still be maintained within the normal index range under the conditions of low temperature or wet coal in winter, without consuming other fuels to maintain the air temperature. The coal mill inlet is equipped with a cold primary air duct, which can adjust the inlet air temperature of the coal mill. When the outlet air temperature of the coal mill is high, the hot air damper is closed and the cold air damper is opened to reduce the amount of hot air entering the coal mill, reduce the inlet air temperature of the coal mill, and keep the outlet air temperature of the coal mill within the normal index.

[0015] The technical solution of the utility model is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the overall structure of a boiler hot air recirculation device of the utility model;

[0017] Reference numerals:

[0018] 1. Coal feeder; 2. Coal mill outlet pipe; 3. Burner; 4. Boiler; 5. Primary air air preheater; 6. Hot primary air duct; 7. Hot secondary air duct; 8. Secondary air air preheater; 9. Blower outlet pipe; 10. Blower; 11. Air inlet; 12. Muffler; 13. Primary fan outlet pipe; 14. Primary fan; 15. Cold primary air duct; 16. Fan inlet damper; 17. Hot air recirculation duct regulating valve; 18. Hot air recirculation duct butterfly valve; 19. Hot air damper; 20. Baffle door; 21. Cold air damper; 22. Coal mill; 23. Coarse powder separator; 24. Hot air recirculation duct. DETAILED DESCRIPTION

[0019] The technical solution of the utility model is further described below through the accompanying drawings and embodiments.

[0020] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] See also Figure 1 The present application discloses a boiler hot air recirculation device, comprising: a coal feeder 1, a coal mill 22, a burner 3, a boiler 4, a primary air preheater 5, a secondary air preheater 8, a primary air fan 14, and an air blower 10;

[0022] The coal feeder 1 delivers coal to the coal mill 22, and a coarse powder separator 23 is installed on the coal mill 22;

[0023] The coarse powder separator 23 and the burner 3 are connected via the coal mill outlet pipe 2, and the gas-powder mixture separated by the coarse powder separator 23 is transported to the burner 3 via the coal mill outlet pipe 2, and the burner 3 is connected to the boiler 4;

[0024] The primary air preheater 5 and the coal mill 22 are connected via a hot primary air duct 6, and the secondary air preheater 8 and the burner 3 are connected via a hot secondary air duct 7;

[0025] The primary fan 14 is provided with a primary fan outlet pipe 13 connected to the primary air air preheater 5, and the blower 10 is provided with a blower outlet pipe 9 connected to the secondary air air preheater 8;

[0026] A hot air recirculation pipe 24 is provided on the hot secondary air duct 7 and connected to the primary air fan 14 , and a cold primary air duct 15 is provided on the primary air fan outlet pipe 13 and connected to the hot primary air duct 6 .

[0027] In order to further optimize the above technical solution, the primary fan 14 and the air supply fan 10 are connected with an air suction port 11 through a pipeline, and a muffler 12 and a fan inlet damper 16 are provided on the pipeline.

[0028] Specifically, air enters the primary fan 14 and the air supply fan 10 through the air inlet 11 and the muffler 12, and whether the air enters the primary fan 14 and the amount of air entering are controlled by the fan inlet damper 16.

[0029] To further optimize the above technical solution, a baffle door 20 is provided on the air inlet pipe of the coal mill 22 , the hot primary air duct 6 is connected to the baffle door 20 , and a hot air damper 19 is provided on the hot primary air duct 6 .

[0030] In order to further optimize the above technical solution, the cold primary air duct 15 is connected to one end of the hot primary air duct 6 connected to the baffle door 20 , and a cold air damper 21 is provided on the cold primary air duct 15 .

[0031] It should be noted that the temperature of the hot air entering the coal mill 22 is controlled by adjusting the cold air damper 21 and the hot air damper 19 respectively, thereby controlling the outlet temperature of the coal mill 22.

[0032] In order to further optimize the above technical solution, a hot air recirculation duct butterfly valve 18 and a hot air recirculation duct regulating valve 17 are provided on the hot air recirculation pipe 24 .

[0033] Specifically, the hot air input to the primary fan 14 is regulated by the hot air recirculation duct butterfly valve 18 and the hot air recirculation duct regulating valve 17 , thereby adjusting the outlet temperature of the primary fan 14 .

[0034] Working process: The coal from the coal feeder 1 is fed into the coal mill 22, and the coarse powder separator 23 on the upper part of the coal mill 22 separates the gas-powder mixture, and feeds it into the burner 3 through the coal mill outlet pipe 2. The burner 3 is connected with a hot secondary air duct 7, and the hot air and the gas-powder mixture are sprayed into the boiler 4 together through the burner 3. The coal mill 22 is connected with a hot primary air duct 6 and a cold primary air duct 15, and the hot primary air duct 6 and the cold primary air duct 15 are respectively provided with a hot air damper 19 and a cold air damper 21. When the outlet temperature of the coal mill 22 is high, the cold air damper 21 is opened to reduce the temperature of the hot air entering the coal mill 22. The cold primary air duct 15 is a branch of the primary fan outlet pipe 13. The air passes through the air inlet 11 and the muffler 12 and enters the primary fan 14. The primary fan outlet One end of the pipe 13 is connected to the primary fan 14, and the other end is connected to the primary air preheater 5. The cold air passes through the primary fan outlet pipe 13 and enters the primary air preheater 5 to be heated. After being heated, it enters the hot primary air duct 6. The hot primary air duct 6 provides hot air to the coal mill 22. The other way connected to the primary fan 14 is the hot air recirculation pipe 24. The hot air recirculation pipe 24 is equipped with a hot air recirculation duct regulating valve 17 and a hot air recirculation duct butterfly valve 18. The hot air recirculation pipe 24 is connected from the hot secondary air duct 7. The secondary hot air is introduced into the inlet of the primary fan 14 through the hot air recirculation pipe 24. The outlet of the secondary air preheater 8 is connected to the hot secondary air duct 7. The inlet of the secondary air preheater 8 is connected to the blower outlet pipe 9. The secondary air preheater 8 heats the secondary air of the blower 10 and sends it into the burner 3.

[0035] Therefore, the utility model adopts a boiler hot air recirculation device of the above structure, and introduces the secondary hot air into the primary fan inlet through the hot air recirculation pipe, thereby increasing the air temperature at the primary fan inlet, increasing the primary fan outlet temperature, increasing the air temperature entering the primary air air preheater, and reducing the heating energy consumption of the primary air air preheater, so that the outlet air temperature of the coal mill can still be maintained within the normal index range under the conditions of low temperature or wet coal in winter, without consuming other fuels to maintain the air temperature. The coal mill inlet is equipped with a cold primary air duct, which can adjust the inlet air temperature of the coal mill. When the outlet air temperature of the coal mill is high, the hot air damper is closed and the cold air damper is opened to reduce the amount of hot air entering the coal mill, reduce the inlet air temperature of the coal mill, and keep the outlet air temperature of the coal mill within the normal index.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that they can still modify or replace the technical solution of the utility model with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the utility model.

Claims

1. A boiler hot air recirculation device, characterized in that: include: Coal feeder, coal mill, burner, boiler, primary air preheater, secondary air preheater, primary fan, blower; The coal feeder conveys coal into the coal mill, and a coarse powder separator is installed on the coal mill; The coarse powder separator and the burner are connected via a coal mill outlet pipe, and the gas-powder mixture separated by the coarse powder separator is transported to the burner via the coal mill outlet pipe, and the burner is connected to the boiler; The primary air preheater and the coal mill are connected via a hot primary air duct, and the secondary air preheater and the burner are connected via a hot secondary air duct; The primary fan is provided with a primary fan outlet pipe connected to the primary air air preheater, and the blower is provided with a blower outlet pipe connected to the secondary air air preheater; The hot secondary air duct is provided with a hot air recirculation pipe connected to the primary air fan, and the primary air fan outlet pipe is provided with a cold primary air duct connected to the hot primary air duct.

2. A boiler hot air recirculation device according to claim 1, characterized in that: The primary fan and the air supply fan are connected with an air suction port through a pipeline, and a muffler and a fan inlet damper are arranged on the pipeline.

3. A boiler hot air recirculation device according to claim 2, characterized in that: The coal mill air inlet pipe is provided with a baffle door, the hot primary air duct is connected to the baffle door, and the hot primary air duct is provided with a hot air damper.

4. A boiler hot air recirculation device according to claim 3, characterized in that: The cold primary air duct is connected to one end of the hot primary air duct connected to the baffle door, and a cold air damper is provided on the cold primary air duct.

5. A boiler hot air recirculation device according to claim 4, characterized in that: The hot air recirculation pipe is provided with a hot air recirculation air duct butterfly valve and a hot air recirculation air duct regulating valve.

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