Boiler combustion air volume control system

Abstract

The utility model discloses a boiler combustion air volume control system which comprises a PLC (programmable logic controller), a heat exchange chamber, an induced draft fan, a secondary blower device, an air blower and a discharging device used for feeding comburent into a boiler hearth, and a high-temperature superheater is arranged inside the top end of the heat exchange chamber; a pressure transmitter is arranged at a hearth negative pressure measuring point of the boiler, first zirconium oxide probes are arranged on the two sides of a smoke inlet of the high-temperature superheater, and a second zirconium oxide probe is arranged on an air outlet in the bottom end of the heat exchange chamber. The detection output end of the first zirconium oxide probe, the detection output end of the second zirconium oxide probe and the detection output end of the pressure transmitter are respectively connected with the PLC. According to the air volume control system, the total air volume, the primary air volume and the secondary air volume can be quickly, efficiently and automatically adjusted according to the operation working conditions of the boiler, and the combustion efficiency and the heat energy utilization rate of the boiler can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of boiler combustion control, and particularly relates to a boiler combustion air volume control system. Background Art

[0002] A boiler is an energy conversion device, which is used to convert electric energy or the heat energy generated by fuel combustion through the boiler and output steam, high-temperature water or organic heat carrier with a certain amount of heat energy for people's production and living needs. Its fuel is mainly natural gas, coal gas or coal. At present, bagasse or bagasse pith from sugarcane pressing is used as the boiler fuel in sugar mills. The existing boiler control system in sugar mills is that except for the automatic control of boiler feed water, the operation of other links needs to be manually adjusted by the experience of boiler operators. The automation degree of the boiler combustion system is not high. Due to the large fluctuation of the moisture content of bagasse or bagasse pith, the feed control is unstable, and it is difficult to adjust the boiler operation conditions in time. Coupled with the skill differences of operators, the air distribution and bagasse or bagasse pith cannot be adjusted to the best state, resulting in large fluctuations in boiler combustion operation, poor working conditions, incomplete combustion, low efficiency, affecting the energy-saving effect, and thus problems such as high energy consumption affecting the up-to-standard discharge of flue gas are caused. Therefore, in order to ensure the safe and stable operation of the boiler, it is necessary to quickly and efficiently automatically adjust the air volume according to the boiler operation conditions to provide the oxygen required for the combustion of bagasse or bagasse pith, achieve a suitable combustion effect, ensure the stability of combustion inside the furnace, ensure the safety of the furnace and reduce the manual adjustment operation of personnel. Summary of the Utility Model

[0003] The purpose of the utility model is to provide a boiler combustion air volume control system. The air volume control system of the utility model can quickly and efficiently automatically adjust the total air volume, primary air volume and secondary air volume according to the boiler operation conditions, and can improve the combustion efficiency and heat energy utilization rate of the boiler, and can provide stable high-temperature steam, reduce energy waste, and ensure the stability and safety of combustion inside the furnace. To achieve the above purpose, the utility model adopts the following technical effects:

[0004] According to one aspect of the present utility model, a boiler combustion air volume control system is provided. The air volume control system includes a PLC controller, a heat exchange chamber, an induced draft fan, a secondary air blowing device, a blower, and a discharging device for feeding combustibles into the boiler furnace. The outlet end of the discharging device is communicated with one side of the combustible feeding port of the boiler. A high-temperature superheater is arranged inside the top end of the heat exchange chamber; the smoke outlet of the boiler is communicated with the high-temperature superheater at the inner top end of the heat exchange chamber through a heat transfer pipe. The bottom end of the heat exchange chamber is communicated with the induced draft fan through a smoke exhaust pipe. The first air outlet of the secondary air blowing device is communicated with the air inlet of the boiler through a first air supply pipe. The second air outlet of the secondary air blowing device is communicated with one side of the combustible feeding port of the boiler through a second air supply pipe. The air blowing conveying main pipe communicated with the air outlet of the blower extends into the heat exchange chamber and then extends out to be communicated with the air inlet of the boiler. A total air volume control valve is arranged on the air blowing conveying main pipe near the air outlet side of the blower. An induced draft control valve is arranged on the smoke exhaust pipe near the air inlet side of the induced draft fan. A pressure transmitter is arranged at the furnace negative pressure tapping point of the boiler. First zirconia probes are arranged on both sides of the flue gas inlet of the high-temperature superheater. A second zirconia probe is arranged on the air outlet at the bottom end of the heat exchange chamber. The detection output ends of the first zirconia probe, the second zirconia probe, and the detection output end of the pressure transmitter are respectively connected to the PLC controller.

[0005] In a further preferred embodiment of the above solution, the air volume control system further includes a steam bubble detection device. The steam bubble detection device includes a main steam header communicated with the steam outlet of the boiler steam drum, a steam flow sensor arranged on the main steam header, and a steam pressure gauge arranged on the boiler steam drum. The steam pressure gauge is electrically connected to the PLC controller. A section of the main steam header between the steam inlet end and the outlet end is wound and arranged inside the high-temperature superheater. A steam flow sensor electrically connected to the PLC controller is arranged on the main steam header near the steam outlet of the boiler steam drum.

[0006] In a further preferred embodiment of the above solution, a steam control valve is arranged on the main steam header extending out of the heat exchange chamber. A steam discharge pipe is connected to the input end side of the steam control valve. A steam discharge valve is arranged on the steam discharge pipe.

[0007] In a further preferred embodiment of the above solution, the secondary air blowing device includes a first fan and a second fan. The first outlet end of the first fan is communicated with the air inlet of the boiler through a first air supply pipe. The second outlet end of the first fan is communicated with the outlet end of the discharging device on one side of the combustible feeding port of the boiler through a second air supply pipe. The first outlet end of the second fan is communicated with the front side and the rear side inside the boiler furnace through a secondary air pipe. The second outlet end of the second fan is communicated with the first air supply pipe through a branch air supply pipe.

[0008] Preferably, a secondary air supply flow valve is provided on the first air supply duct on the side of the first outlet end of the first fan close to the first fan. The outlet end side of the secondary air duct is respectively communicated with the upper end of the front side and the upper and lower ends of the rear side in the boiler furnace through the first branch air ducts. A second branch air duct communicated with the first air supply duct is provided at the lower end of the front side in the boiler furnace. A secondary first air supply flow control valve is respectively provided on the first branch air duct and the second branch air duct, and a secondary second air supply flow control valve is provided on the branch air supply duct.

[0009] Preferably, the discharging device includes a combustible conveyor belt, a receiving hopper, a blanking pipe, a scraping plate and a spiral metering blanking device. A plurality of receiving hoppers are respectively provided below the combustible conveyor belt. The outlet end of each receiving hopper is respectively communicated with the combustible supply inlet of the boiler through the blanking pipe. The scraping plates are respectively provided on the side of the combustible conveyor belt above each discharging hopper. The spiral metering blanking device is provided at a position close to the outside of the boiler at the lower end of the blanking pipe. An air outlet nozzle extending into the inner part of the outlet end of each blanking pipe is provided at one end of the air outlet of the second air supply duct and between the outlet of the spiral metering blanking device and the combustible supply inlet of the boiler.

[0010] Preferably, a combustible material height sensor is provided in the blanking pipe between the outlet of the receiving hopper and the inlet of the spiral metering blanking device, and the combustible material height sensor is electrically connected to the PLC controller.

[0011] In summary, the present utility model adopts the above technical solutions, and the present utility model has the following technical effects:

[0012] The air volume combustion control system of the present utility model can quickly and efficiently automatically adjust the total air volume, primary air volume and secondary air volume according to the operating conditions of the boiler, provide sufficient oxygen required during the combustion process of bagasse or bagasse pith in the boiler, enable the boiler to achieve the purpose of automatically coordinating and controlling the slag addition amount and air supply volume during combustion, make the combustion of bagasse or bagasse pith combustibles more sufficient in the furnace (combustion chamber) of the boiler, can also improve the combustion efficiency and heat energy utilization rate of the boiler, provide stable high-temperature steam, reduce energy waste, ensure the stability and safety of combustion inside the furnace, and reduce the influence of manual control factors under the normal operation of the boiler and normal production. Description of the Drawings

[0013] Figure 1 is the system schematic diagram of a boiler combustion air volume control system of the present utility model;

[0014] Figure 2 is the control schematic diagram of a boiler combustion air volume control system of the present utility model;

[0015] In the attached drawings, there are boiler 1, discharging device 2, heat exchange chamber 3, induced draft fan 5, secondary air blowing device 4, blower 6, bubble steam detection device 7, boiler steam drum 8, pressure transmitter 9, heat transfer pipe 10, exhaust pipe 11, induced draft control valve 11a, first air supply pipe 12, second air supply pipe 12a, air outlet spray pipe 12b, air inlet 13, high-temperature superheater 30, first zirconia probe 31, second zirconia probe 32, first fan 40, second fan 41, secondary air supply flow valve 41b, secondary air pipe 42, first branch air pipe 42a, second branch air pipe 42b, secondary first air supply flow control valve 42c, secondary second air supply flow control valve 42d, branch air supply pipe 43, discharge chimney 50, air blowing and conveying main pipe 60, total air volume control valve 61, primary air supply pipe 62, primary air control valve 62a, main steam main pipe 71, steam control valve 71a, steam drain valve 71c, steam discharge pipe 71b, steam flow sensor 72, steam pressure gauge 73, combustible conveyor belt 201, receiving hopper 202, blanking pipe 203, scraping plate 204, screw metering feeder 205, combustible material height sensor 206. Detailed implementation manners

[0016] In order to make the objectives, technical solutions and advantages of the present utility model clearer and more understandable, the following provides preferred embodiments with reference to the attached drawings to further elaborate on the present utility model in detail. However, it should be noted that many details listed in the description are only for enabling the reader to have a thorough understanding of one or more aspects of the present utility model, and these aspects of the present utility model can be implemented even without these specific details.

[0017] Combined with Figure 1 and Figure 2As shown in the figure, a boiler combustion air volume control system according to the present utility model, the air volume control system includes a PLC controller, a heat exchange chamber 3, an induced draft fan 5, a secondary air blowing device 4, a blower 6, and a discharging device 2 for feeding combustion materials into the furnace of the boiler 1. The outlet end of the discharging device 2 is communicated with one side of the combustion material feeding port of the boiler 1. A high-temperature superheater 30 is arranged inside the top end of the heat exchange chamber 3. The smoke outlet of the boiler 1 is communicated with the high-temperature superheater 30 at the inner top end of the heat exchange chamber 2 through a heat transfer pipe 10. The bottom end of the heat exchange chamber 3 is communicated with the induced draft fan 5 through a smoke exhaust pipe 11. The first air outlet of the secondary air blowing device 4 is communicated with the air inlet 13 of the boiler 1 through a first air supply pipe 12. The second air outlet of the secondary air blowing device 4 is communicated with one side of the combustion material feeding port of the boiler 1 through a second air supply pipe 12a. The air blowing main pipe 60 communicated with the air outlet of the blower 6 extends into the heat exchange chamber 3 and then is communicated with the air inlet 13 of the boiler 1. A pressure transmitter 9 is arranged at the furnace negative pressure tapping point of the boiler 1. First zirconia probes 31 are arranged on both sides of the flue gas inlet of the high-temperature superheater 30. A second zirconia probe 32 is arranged on the air outlet at the bottom end of the heat exchange chamber 3. The oxygen content in the boiler combustion process is obtained in real time through the zirconia probes. The detection output ends of the first zirconia probe 31, the second zirconia probe 32, and the detection output end of the pressure transmitter 9 are respectively connected to the PLC controller. The air volume control system further includes a steam bubble detection device. The steam bubble detection device 7 includes a main steam header 71 communicated with the steam outlet of the boiler steam drum 8, a steam flow sensor 72 arranged on the main steam header 71, and a steam pressure gauge 73 arranged on the boiler steam drum 8. The steam pressure gauge 73 is electrically connected to the PLC controller. A section of the main header between the steam inlet end and the outlet end is coiled and arranged inside the high-temperature superheater 30. A steam flow sensor 72 electrically connected to the PLC controller is arranged on the main steam header 71 near the steam outlet side of the boiler steam drum 8.A total air volume control valve 61 is provided on the main air delivery pipe 60 on the air outlet side near the blower 6, and an induced draft control valve 11a is provided on the exhaust pipe 11 on the induced draft port side near the induced draft fan 5. In the present utility model, bagasse or bagasse pith combustibles are fed into the furnace (combustion chamber) of the boiler 1 through the discharging device 2 for combustion, and the water in the boiler steam drum 8 is heated to generate high-temperature steam. The hot waste gas generated during the combustion process of the bagasse or bagasse pith combustibles is sent into the high-temperature superheater 30 in the heat exchange chamber 3 through the exhaust pipe 11. After the high-temperature superheater 30 reduces the temperature of the waste gas, it flows into the bottom of the heat exchange chamber 3 and is sent into the emission chimney 50 through the induced draft fan 5 for emission. The heat generated by the combustion of bagasse or bagasse pith in the furnace of the boiler 1 heats the water in the boiler steam drum 8 to generate water vapor, which is sent into the high-temperature superheater 30 through the main steam pipe 71 to heat, insulate, and regulate the temperature of the steam in the main steam pipe 71 to ensure the saturation of the steam, and then extends from the heat exchange chamber 3 to provide stable high-temperature steam for the sugar-making equipment; if the temperature of the air sent into the furnace by the blower 6 is too low, it will affect the temperature in the furnace. Therefore, the pipeline of the main air delivery pipe 60 passes through the heat exchange chamber 3 to exchange heat for the air in the main air delivery pipe 60. After raising the temperature of the air, it is sent into the air inlet 13 of the boiler 1 through the main air delivery pipe 60 to provide the total air volume, that is, the total oxygen volume and the primary air for the combustion of bagasse or bagasse pith, and improve the combustion efficiency of bagasse in the furnace of the boiler 1. By controlling the amount of bagasse or bagasse pith fed into the boiler furnace through the discharging device 2 and the amount of combustion-supporting air sent into the boiler furnace, the steam flow generated by the boiler steam drum 8 is stably maintained.

[0018] In the present utility model, as Figure 1 and Figure 2 shown, a steam control valve 71a is provided on the main steam pipe 71 on the side extending out of the heat exchange chamber 3. A steam discharge pipe 71b is connected to the input side of the steam control valve 71a, and a steam drain valve 71c is provided on the steam discharge pipe 71b. The steam pressure in the boiler steam drum 8 is detected by a steam pressure gauge 73. If the steam pressure is too high, the opening of the steam control valve 71a is increased to increase the steam supply, or the steam drain valve 71c is opened for pressure relief, and the supply of combustibles is reduced and the air volume is decreased.

[0019] As Figure 1 and Figure 2As shown, the secondary air blowing device 4 includes a first blower 40 and a second blower 41. The first outlet end of the first blower 40 is communicated with the air inlet 13 of the boiler 1 through a first air delivery pipe 12. The second outlet end of the first blower 40 is communicated with the outlet end of the discharging device 2 on the side of the fuel delivery inlet of the boiler 1 through a second air delivery pipe 12a. The first outlet end of the second blower 41 is communicated with the front side and the rear side inside the furnace of the boiler 1 through a secondary air pipe 42. The second outlet end of the second blower 41 is communicated with the first air delivery pipe 12 through a branch air delivery pipe 43. A secondary air blowing flow valve 41b is arranged on the first air delivery pipe 12 on one side close to the first outlet end of the first blower 40. One side of the outlet end of the secondary air pipe 42 is respectively communicated with the upper end of the front side inside the furnace of the boiler 1 and the upper and lower ends of the rear side through a first branch air pipe 42a. A second branch air pipe 42b communicated with the first air delivery pipe 12 is arranged at the lower end of the front side inside the furnace of the boiler 1. Secondary first air blowing flow control valves 42c are respectively arranged on the first branch air pipe 42a and the second branch air pipe 42b. A secondary second air blowing flow control valve 42d is arranged on the branch air delivery pipe 43. Most of the air sent by the blower 6 through the air blowing delivery main pipe 60 is preheated in the heat exchange chamber 3 and then sent to the air inlet 13 of the boiler 1 to reach the furnace (combustion chamber) of the boiler 1, so as to assist the combustion of bagasse. The air flow rate sent into the air inlet 13 of the boiler 1 is controlled by the total air volume control valve 61 to adjust the total amount of oxygen required during the combustion of bagasse. The second outlet end of the first blower 40 blows air into the fuel delivery inlet of the boiler through the first air delivery pipe 12 and the second air delivery pipe 12a, and quickly sends the bagasse or bagasse pith fuel sent by the discharging device 2 into the furnace of the boiler 1 for combustion, which can not only provide oxygen during combustion, but also evenly send the bagasse or bagasse pith fuel into the furnace for combustion. The first outlet end of the first blower 40 also sends secondary air into the furnace from the air inlet 13 of the boiler 1 through the second air delivery pipe 12a and the secondary air blowing flow valve 41b;

[0020] During the air volume adjustment process, the secondary air supply flow valve 41b can be closed, the second blower 41 can be started, and the secondary air can be sent into the furnace from the air inlet 13 of the boiler 1 through the branch air supply pipe 43 and the secondary second air supply flow control valve 42d. At the same time, the secondary first air supply flow control valves 42c on the first branch air pipe 42a and the second branch air pipe 42b are opened, and the secondary air is sent into the upper end of the front side, the upper and lower ends of the rear side, and the lower end of the front side of the furnace of the boiler 1 at the same time to adjust the air volume of the furnace. At the same time, a primary air supply pipe 62 is provided on the air supply main pipe 60 on the outlet end side close to the total air volume control valve 61. One end of the primary air supply pipe 62 is connected to the air supply main pipe 60 on the outlet end side of the total air volume control valve 61, and the other end of the primary air supply pipe 62 is directly communicated with the air inlet 13 of the boiler 1 and / or the top end of the furnace of the boiler 1. A primary air control valve 62a is provided on the primary air supply pipe 62. The ratio of the pipe diameter of the primary air supply pipe 62 to the pipe diameter of the air supply main pipe 60 is at least 1:5 to 10, that is, the air volume ratio of the primary air supply pipe 62 to the total air volume provided by the total air volume control valve 61 is at least 1:5 to 10 (the total air volume is 5 to 10 times the primary air volume). When the primary air control valve 62a is closed, the total air volume generated by the blower 6 is sent into the furnace (combustion chamber) of the boiler 1 through the air supply main pipe 60 via the air inlet 13 to provide sufficient total air volume (oxygen content). During the combustion process, the primary air control valve 62a is opened, and the primary air supply pipe 62 is used to directly perform side blowing and / or top blowing on the furnace of the boiler 1 without preheating to provide the primary air volume required during combustion, and to supplement and correct the primary air during the air volume control process. Sufficient air volume is sent to all positions in the furnace to enable the bagasse or bagasse pith combustibles to obtain sufficient oxygen during combustion, ensuring complete and sufficient combustion. The primary air and the secondary air are directly sent to each position of the furnace of the boiler 1 without preheating, saving the air preheating process and directly providing the oxygen required during the combustion process, and being able to directly adjust the negative pressure in the combustion process in the boiler 1.

[0021] As Figure 1 and Figure 2As shown, the discharging device 2 includes a combustible conveyor belt 201, a receiving hopper 202, a blanking pipe 203, a scraping plate 204, and a screw metering feeder 205. A plurality of receiving hoppers 202 are respectively arranged below the combustible conveyor belt 201. The outlet end of each receiving hopper 202 is respectively connected to the combustible inlet of the boiler 1 through a blanking pipe 203. The scraping plates 204 are respectively arranged on the side part of the combustible conveyor belt 201 above each receiving hopper 202. The screw metering feeder 205 is arranged at a position close to the outside of the boiler 1 at the lower end of the blanking pipe 203. An air outlet nozzle 12b extending into the inner part of the outlet end of each blanking pipe 203 is arranged at the air outlet end of the second air supply pipe 12a and between the outlet of the screw metering feeder 205 and the combustible inlet of the boiler 1. A combustible material height sensor 206 is arranged in the blanking pipe 203 between the lower part of the outlet of the receiving hopper 202 and the inlet of the screw metering feeder 205. The combustible material height sensor is electrically connected to the PLC controller. At a distance of 1 - 1. from the inlet of the screw metering feeder 205A combustion material height sensor 206 is set at a position 5m away. After the combustion material in the receiving hopper 202 is fed into the screw metering feeder 205 and the bagasse or bagasse pith is quantitatively sent out, it continues to fall along the downcomer 203 and approaches the combustion material inlet of the boiler 1. The air blown out by the air outlet nozzle 12b accelerates and disperses the bagasse or bagasse pith again, and it burns in the furnace of the boiler 1. When the bagasse or bagasse pith combustion material is lower than the position where the combustion material height sensor 206 is located, the combustion material conveyor belt 201 transports the bagasse or bagasse pith combustion material to the position of the scraping plate 204. The scraping plate 204 pushes the bagasse or bagasse pith combustion material into the receiving hopper 202 and slides along the downcomer 203 to the inlet end of the screw metering feeder 205, so that the materials required for the combustion of the boiler 1 can be replenished in time, the bagasse or bagasse pith combustion material can be stably discharged and constantly supplied, and the combustion safety of the boiler is satisfied; when the downcomer 203 where the bagasse or bagasse pith combustion material is located reaches the combustion material height sensor 206, the replenishment supply operation stops, and the amount of combustion material sent out by the screw metering feeder 205 is adjusted according to the steam flow change condition of the main steam header 71 and sent into the furnace of the boiler 1. It can not only supplement the required amount of bagasse and heat control the boiler steam drum 8, but also effectively optimize the negative pressure and boiler load changes during the combustion process in the furnace of the boiler 1; in the present utility model, the blower 6 sends air into the furnace of the boiler 1 through the air delivery main pipe 60 as the main oxygen source during the combustion of bagasse or bagasse pith. The first outlet end of the first fan 40 sends air into the furnace of the boiler 1 through the first air duct 12 as the secondary air to provide oxygen supplement during the combustion of bagasse or bagasse pith to improve the combustion rate of bagasse or bagasse pith; at the same time, air is blown into the combustion material inlet of the boiler through the second outlet end of the first fan 40, the second air duct 12a and the air outlet nozzle 12b, so that the bagasse or bagasse pith combustion material is quickly and evenly sent into the furnace of the boiler 1 for combustion, and it can also provide oxygen during combustion, increase the oxygen content during combustion, effectively improve the burning rate of the bagasse or bagasse pith combustion material, and reduce flue gas emissions.

[0022] Such as Figure 1 、 Figure 2As shown in the figure, the combustion air volume control process of a boiler combustion air volume control system of the present utility model is further elaborated. When the PLC controller feeds combustibles into the furnace of the boiler 1 through the screw metering feeder 205 of the discharging device 2 for combustion, the blower 6 blows the total combustion air volume into the furnace of the boiler 1 through the main air conveying pipe 60 and also forms the primary air. The secondary air blowing device 4 blows the secondary air and the spraying air into different positions on the front and rear sides of the furnace of the boiler 1 through the first air pipe 12 and the second air pipe 12a respectively. During the combustion process of bagasse or bagasse pith combustibles in the furnace of the boiler 1, the PLC controller obtains the first oxygen content in the high-temperature superheater 30 in real time through the first zirconia probe 31 and obtains the second oxygen content in the bottom of the heat exchange chamber 3 in real time through the second zirconia probe 32. The PLC controller judges the obtained first oxygen content and second oxygen content, and successively reduces and adjusts the total air volume opening of the air damper of the blower 6 and the secondary air opening of the air damper of the secondary air blowing device 4 according to the judgment result, and reduces or increases the air volume into the furnace. The present utility model controls the oxygen (O 2 ) content of the gas in the furnace by adjusting the total combustion air, primary air, secondary air, and spraying air entering the furnace. The required air volume can be achieved through the adjustment of the total combustion air and primary air, ensuring that the bagasse burns completely in the furnace and can provide sufficient oxygen, and at the same time achieving the purpose of adjusting the temperature in the furnace. By adjusting the secondary air, the staged air volume of the secondary air is controlled to achieve the purpose of full combustion of the bagasse fuel suspended in the middle of the furnace. By adjusting the spraying air, the air volume of the spraying air is controlled to quickly disperse the bagasse after it enters the furnace, preventing the formation of bagasse clusters and causing local deflagration, and maintaining the stability of the furnace pressure;

[0023] And at the same time, the real-time negative pressure value inside the furnace of the boiler 1 is obtained. If the real-time negative pressure value is greater than the preset negative pressure value, it can be judged that there is a large amount of flue gas and a large negative pressure inside the furnace of the boiler 1. Therefore, the spraying air volume blown into the combustion material inlet is increased in sequence and the air draft opening of the damper of the induced draft fan 5 is decreased, so as to achieve the purpose of adjusting the induced draft air volume. At the same time, the amount of bagasse combustion material fed into the furnace can be adjusted. After sufficient combustion, the bagasse combustion material is fed again. If the negative pressure inside the furnace is too large and the air draft opening of the induced draft fan 5 is too large, taking away too much heat may cause incomplete combustion; the air draft opening (rotation speed) of the damper of the induced draft fan 5 is controlled to adjust the induced draft air volume, so as to control the furnace negative pressure to meet the requirements of boiler operation. In the present invention, the real-time steam flow value inside the main steam header 71 is also obtained in real time through the steam flow sensor 72; if the steam flow value is less than the preset steam flow value, the combustion material is fed into the furnace of the boiler 1 through the spiral metering feeder 205, heating the boiler steam drum 8 to generate a stable steam flow, and blowing air into the furnace of the boiler 1 through the blower 6, and adjusting the air draft opening of the damper of the induced draft fan 5 according to the change amount between the first oxygen content and the second oxygen content, so as to achieve the purpose of adjusting the negative pressure during combustion inside the furnace of the boiler 1 and maintaining it in a relatively stable state. According to the change amount between the first oxygen content and the second oxygen content, it can be judged whether the combustion material inside the furnace is completely burned. If it can be completely burned and the oxygen content is within the preset range, the air draft opening of the damper of the induced draft fan 5 is reduced, so as to reduce the induced draft air volume, ensure that the temperature inside the high-temperature superheater 30 in the main steam header 71 can be maintained, maintain the stability of the steam in the main steam header 71, and reduce the flue gas emission and heat loss during the combustion process of the bagasse fuel.

[0024] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A boiler combustion air volume control system, characterized in that: The air volume control system includes a PLC controller, a heat exchange chamber, an induced draft fan, a secondary air blowing device and a blower and a discharge device for delivering the combustion material into the boiler furnace, the outlet end of the discharge device is connected to one side of the combustion material delivery inlet of the boiler, and a high-temperature superheater is arranged inside the top of the heat exchange chamber; the smoke exhaust port of the boiler is connected to the high-temperature superheater at the top of the heat exchange chamber through a heat transport pipe, the bottom end of the heat exchange chamber is connected to the induced draft fan through a smoke exhaust pipe, the first air outlet of the secondary air blowing device is connected to the air inlet of the boiler through a first air supply pipe, and the second air outlet of the secondary air blowing device is connected to the combustion material delivery inlet of the boiler through a second air supply pipe. The air outlet of the blower is connected to the side, and the air delivery main pipe connected to the air outlet of the blower extends out to be connected to the air inlet of the boiler after entering the heat exchange chamber. A total air volume control valve is arranged on the air delivery main pipe on the side close to the air outlet of the blower, and an induced draft control valve is arranged on the smoke exhaust pipe on the side close to the induced draft fan. A pressure transmitter is arranged at the negative pressure taking point of the furnace of the boiler, a first zirconia probe is arranged on both sides of the flue gas inlet of the high-temperature superheater, and a second zirconia probe is arranged on the air outlet in the bottom end of the heat exchange chamber, and the detection output end of the first zirconia probe, the detection output end of the second zirconia probe and the detection output end of the pressure transmitter are respectively connected to the PLC controller.

2. A boiler combustion air volume control system according to claim 1, characterized in that: The air volume control system also includes a bubble steam detection device, which includes a main steam main pipe connected to the steam outlet of the boiler drum, a steam flow sensor arranged on the main steam main pipe, and a steam pressure gauge arranged on the boiler drum. The steam pressure gauge is electrically connected to the PLC controller. A section of the main steam main pipe between the steam inlet end and the outlet end is coiled in the high-temperature superheater. A steam flow sensor electrically connected to the PLC controller is arranged on the main steam main pipe close to the steam outlet of the boiler drum.

3. A boiler combustion air volume control system according to claim 2, characterized in that: A steam control valve is arranged on the main steam main pipe extending out of the heat exchange chamber, a steam discharge pipe is connected to the input end of the steam control valve, and a steam discharge valve is arranged on the steam discharge pipe.

4. A boiler combustion air volume control system according to claim 1 or 2, characterized in that: The secondary blowing device includes a first fan and a second fan, the first outlet end of the first fan is connected to the air inlet of the boiler through a first air supply pipe, the second outlet end of the first fan is connected to the outlet end of the unloading device on the combustion material supply inlet side of the boiler through a second air supply pipe, the first outlet end of the second fan is connected to the front and rear sides of the boiler furnace through the secondary air duct, and the second outlet end of the second fan is connected to the first air supply pipe through a branch air supply pipe.

5. A boiler combustion air volume control system according to claim 4, characterized in that: A secondary air supply flow valve is arranged on the first air supply duct on the side of the first outlet end close to the first fan, and one side of the outlet end of the secondary air duct is connected with the upper end of the front side and the upward and lower ends of the rear side of the boiler furnace through the first branch air duct respectively, and a second branch air duct connected with the first air supply duct is arranged at the lower end of the front side of the boiler furnace, and secondary first air supply flow control valves are respectively arranged on the first branch air duct and the second branch air duct, and a secondary second air supply flow control valve is arranged on the branch air supply duct.

6. A boiler combustion air volume control system according to claim 4, characterized in that: The unloading device includes a combustion material conveyor belt, a receiving hopper, a dropping pipe, a scraper plate and a spiral quantitative feeder. A plurality of receiving hoppers are respectively arranged below the combustion material conveyor belt. The outlet end of each receiving hopper is connected to the combustion material inlet of the boiler through a dropping pipe. The scraper plates are respectively arranged on the sides of the combustion material conveyor belt above each unloading hopper. The spiral quantitative feeder is arranged at the lower end of the dropping pipe close to the outside of the boiler. At one end of the air outlet of the second air supply pipe and between the outlet of the spiral quantitative feeder and the combustion material inlet of the boiler, air outlet nozzles are respectively arranged, which extend into the outlet end of each dropping pipe.

7. A boiler combustion air volume control system according to claim 6, characterized in that: A combustion material height sensor is arranged in the material discharge pipe between the lower part of the receiving hopper outlet and the inlet of the spiral quantitative discharger, and the combustion material height sensor is electrically connected to the PLC controller.

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