Coal mill heating system with isolation and dust deposition prevention functions

Abstract

The invention discloses a coal mill heating system with isolation and ash deposition prevention functions. According to the technical scheme, the system comprises an air heater body, an inlet air path assembly, an outlet air path assembly, a control unit and an emergency bypass assembly. The inlet air path assembly comprises a three-way air source pipe, a cyclone pre-separator and an inlet isolation assembly, the three-way air source pipe is connected with double primary air mother pipes of the unit, and the inlet isolation assembly is of a double-gate-plate inflation sealing structure and is provided with a drain outlet; a multi-layer snakelike heat exchange tube set and a pulse blowing mechanism are arranged in the air heater body, and heat exchange tubes are provided with anti-sticking coatings. The outlet adjusting assembly is an intelligent electric adjusting butterfly valve of an integrated detection module; the control unit realizes linkage of each component and DCS communication with the unit through the PLC main controller; and the emergency bypass assembly guarantees continuous air supply during failure. The system has the beneficial effects that system air source switching is flexible, defects can be eliminated under pressure when faults occur, dust accumulation is effectively prevented, temperature regulation and control are accurate, and operation reliability and economical efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal mills, and relates to a coal mill warm air system with isolation and anti-dust functions. BACKGROUND

[0002] The coal mill warm air system is a core device for guaranteeing the drying output of the coal pulverizing system and improving the reliability of boiler ignition during the start-up stage of the thermal power unit. It needs to heat the primary air to a temperature suitable for the drying needs of the coal type and then pass it into the coal mill mixed air pipeline. However, the existing technology has many pain points: the air supply depends on the mother pipe corresponding to a single primary air fan, and if the fan fails, the system cannot be put into operation, with poor flexibility; there is a lack of reliable isolation devices, and when the warm air heater body or the pipeline leaks, the unit load needs to be reduced or even stopped to eliminate the defects, which seriously affects the operation economy; the dust carried by the primary air is easy to accumulate on the surface of the heat exchange pipe, resulting in a continuous decrease in the heat exchange efficiency, and there is no automatic dust removal mechanism; the mixed air temperature regulation mainly depends on manual valves, and the precision is insufficient to adapt to the conditions such as unit start-stop and load change; and no emergency air supply path is provided, and the core component failure will interrupt the air supply of the coal mill. These problems result in low start-up reliability, high operation and maintenance cost, and poor operation stability of the existing system, which is difficult to meet the efficient operation needs of the unit.

[0003] Therefore, the present application provides a coal mill warm air system with isolation and anti-dust functions to solve the above problems. SUMMARY

[0004] In view of the problems existing in the prior art, the present application discloses a coal mill warm air system with isolation and anti-dust functions, which adopts the technical scheme of comprising a warm air heater body, an inlet air path assembly, an outlet air path assembly, and a control unit. The inlet air path assembly comprises a three-way air source pipe, a cyclone pre-separator, and an inlet isolation assembly connected in series. Two air inlet ports of the three-way air source pipe are used to connect the primary air mother pipes of units A and B, respectively. The air outlet port of the three-way air source pipe is in communication with the air inlet of the cyclone pre-separator. The bottom of the cyclone pre-separator is provided with a dust collector with an electric dust removal valve. The inlet of the inlet isolation assembly is in sealed connection with the air outlet of the cyclone pre-separator. The outlet of the inlet isolation assembly is in communication with the primary air inlet of the warm air heater body through a flange. The steam inlet of the warm air heater body is connected to an auxiliary steam pipeline. The condensate outlet of the warm air heater body is connected to a drain pipeline. The outlet air path assembly comprises an outlet adjustment assembly and a flexible sealing section connected in series. The inlet of the outlet adjustment assembly is in communication with the primary air outlet of the warm air heater body. The outlet of the flexible sealing section is used to connect to the coal mill mixed air pipeline. The control unit is electrically connected with the inlet isolation assembly, the outlet adjustment assembly, and the electric dust removal valve of the dust collector, respectively, for controlling the operating state of each assembly.

[0005] As a preferred scheme of the present application, the import isolation assembly is a double-gate inflatable sealing isolation valve, a sealed gas cavity is formed between the double-gate inflatable sealing isolation valve, the sealed gas cavity is connected with an inert gas supply pipeline, and a pressure control valve is arranged on the pipeline; a blowdown port is arranged at the bottom of a valve cavity of the double-gate inflatable sealing isolation valve, the blowdown port is communicated with the ash hopper through a pipeline, and an electromagnetic valve is arranged on the pipeline; the pressure control valve and the electromagnetic valve are electrically connected with a control unit; by adopting the double-gate inflatable sealing isolation valve, the medium flow can be blocked in a fault state, and the pressure support is provided for the defect elimination; in normal operation, the leakage and the ash accumulation are prevented, and the internal blockage risk is reduced.

[0006] As a preferred scheme of the present application, the heater body is internally provided with a heat exchange pipe group, the heat exchange pipe group is composed of a plurality of parallelly arranged serpentine pipes, the pipe openings on the right side of the serpentine pipes are respectively communicated with steam inlet pipelines which vertically upwardly penetrate the heater body, the pipe openings on the left side of the serpentine pipes are respectively communicated with condensate outlet pipelines which vertically downwardly penetrate the heater body, and a pulse purging mechanism is arranged above the heat exchange pipe group; the pulse purging mechanism comprises a plurality of purging nozzles which are uniformly arranged along the length direction of the heat exchange pipe group, and a pulse distributor which is connected with the nozzles, the pulse distributor is connected with a compressed air source through a pulse valve; a pressure sensor is arranged at the primary air inlet and the outlet of the heater body respectively, the pressure sensors are electrically connected with a control unit, and the control unit controls the opening and closing frequency of the pulse valve according to the pressure difference signals of the two pressure sensors; by adopting the heat exchange pipe group composed of the plurality of parallelly arranged serpentine pipes, the heat exchange efficiency of the gas can be effectively improved, the condensate after heat exchange can be effectively discharged, and in addition, the pulse purging mechanism at the upper part of the heat exchange pipe group can effectively reduce the dust accumulation, so that the heater body is prevented from being blocked by the dust.

[0007] As a preferred scheme of the present application, the outlet adjusting assembly is an intelligent electric regulating butterfly valve, the intelligent electric regulating butterfly valve is integrated with a flow detection module and a temperature feedback module, a detection probe of the temperature feedback module extends into a mixed air pipe of the coal mill, the intelligent electric regulating butterfly valve is electrically connected with a PID controller and a control unit, the control unit adjusts the opening of the intelligent electric regulating butterfly valve according to the mixed air temperature detected by the temperature feedback module, and dynamic matching of the hot primary air flow and the mixed air temperature is realized through intelligent linkage: taking the intelligent electric regulating butterfly valve as an execution main body, the integrated temperature feedback module collects the actual temperature of the mixed air in real time through the probe extending into the mixed air pipe of the coal mill, synchronously monitors the output flow of the hot primary air through the flow detection module, and transmits signals of the two to the control unit through the PID controller; the control unit compares the deviation between the measured temperature and the required temperature of the coal mill, calculates optimal adjusting parameters through a PID algorithm, outputs instructions to the intelligent electric regulating butterfly valve to adjust the opening of the intelligent electric regulating butterfly valve, the opening of the intelligent electric regulating butterfly valve is increased, the flow of the hot primary air is increased, the temperature of the mixed air is increased, the opening of the intelligent electric regulating butterfly valve is reduced, the flow is reduced, the temperature of the mixed air is reduced, and finally, precise and stable control of the temperature of the mixed air is realized, so that the drying effect of the coal pulverizing system is adapted to the requirements of different working conditions such as unit start-up and load change.

[0008] As a preferred scheme of the present application, the two air inlet ports of the three-way air source pipe are provided with electric guide baffles, shaft end portions of the electric guide baffles are connected with servo motors installed on the upper portion of the pipe wall, and the servo motors are electrically connected with a control unit; the inner wall of the three-way air source pipe is coated with a wear-resistant ceramic coating, and a circular arc transition guide surface is arranged at the corner of the three-way air source pipe; by adjusting the opening of the electric guide baffles through the servo motor, the two air inlet ports of the three-way air source pipe can be controlled respectively, and the flexibility of the device is improved.

[0009] As a preferred scheme of the present application, the surface of the heat exchange pipe group is coated with a polytetrafluoroethylene anti-sticking coating, and the thickness of the coating is 50-100 μm; the two ends of the heat exchange pipe group are connected with the body shell of the air heater through pipe plates, the windward surface of the pipe plate is provided with honeycomb guide holes, and the surface is sprayed with a tungsten carbide wear-resistant layer, and the bottom of the shell of the air heater body is provided with an ash discharge pipe with a solenoid valve.

[0010] As a preferred scheme of the present application, an emergency bypass assembly is further included, which comprises a bypass pipeline, one end of the bypass pipeline is connected to the inlet air path pipeline between the cyclone pre-separator and the inlet isolation assembly, and the other end is connected to the outlet air path pipeline between the outlet adjusting assembly and the flexible sealing section; an emergency shut-off valve and a check valve are sequentially arranged on the bypass pipeline, the emergency shut-off valve is electrically connected with the control unit, and the opening and closing state of the emergency shut-off valve is interlocked with the inlet isolation assembly and the outlet adjusting assembly; when the inlet isolation assembly, the heater body or the outlet adjusting assembly needs to be urgently isolated due to failure, the control unit triggers the interlocking logic immediately: the inlet isolation valve and the outlet adjusting butterfly valve are closed, and the emergency shut-off valve of the emergency bypass assembly is opened. The primary air directly flows from the "cyclone pre-separator outlet" to the "flexible sealing section inlet" through the bypass pipeline, ensuring that the coal mill does not interrupt the air supply; the check valve on the bypass pipeline can prevent the mixed air from flowing backward, avoiding pressure disorder in the system.

[0011] As a preferred scheme of the present application, the control unit comprises a PLC main controller, a human-computer interaction terminal and a wireless transmission module; the PLC main controller is electrically connected with each actuator and sensor respectively, for receiving detection signals and outputting control instructions; the human-computer interaction terminal is used for displaying system operation parameters, including primary air temperature, pressure, flow and equipment state, and supports manual / automatic mode switching; the wireless transmission module is used for communicating with the unit DCS system, realizing remote monitoring and linkage control; the PLC main controller of the control unit receives each sensor signal in real time, and outputs control instructions to each actuator, such as a servo motor, an electric ash discharge valve, a pulse valve, a pressure control valve and an emergency shut-off valve, according to a preset program; the human-computer interaction terminal displays the primary air temperature, pressure, flow and equipment operation state, such as valve opening and closing and pulse purging frequency, in real time, and supports "manual / automatic" mode switching: in automatic mode, the system is autonomously regulated and controlled, and in manual mode, it can be used for maintenance and debugging; the wireless transmission module uploads system data to the unit DCS system, realizing remote monitoring and linkage control of unit start-stop and load adjustment.

[0012] The present application has the following advantages: The three-way air source pipeline is matched with an electrically-driven flow guide baffle and a servo motor, realizing flexible switching and air volume adjustment of the primary air mother pipelines of the units A and B, and completely solving the problem of single air source dependence; The double-gate inflatable sealing isolation valve and the pressure control valve of the inlet isolation assembly are matched with the blowdown port, realizing pressurized defect isolation during failure, and avoiding leakage and ash accumulation through inert gas sealing and automatic blowdown; The cyclone pre-separator, the polytetrafluoroethylene anti-sticking coating of the heat exchange pipe group and the pulse purging mechanism and the pressure sensor form a "pre-separation - anti-sticking - intelligent ash removal" triple anti-ash accumulation system, greatly improving the heat exchange efficiency; The intelligent electric regulating butterfly valve of the outlet regulating assembly is linked with the control unit through the PID controller to realize accurate regulation and control of the mixed air temperature; the emergency bypass assembly is provided with the emergency cut-off valve and the check valve linked in control to ensure that the air supply of the coal mill is not interrupted in case of failure; the PLC main controller of the control unit and the wireless transmission module realize intelligent monitoring of the whole system and linkage with the unit DCS, thereby improving the reliability, economy and operation convenience of the system as a whole. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of the present application; Figure 2 It is a schematic diagram of the body of the air heater of the present application; Figure 3 It is a cross-sectional view of the body of the air heater of the present application; Figure 4 It is a schematic diagram of the pulse purging mechanism of the body of the air heater of the present application; Figure 5 It is a schematic diagram of the inlet air path assembly of the present application; Figure 6 It is a cross-sectional view of the three-way air source pipe of the inlet air path assembly of the present application; Figure 7 It is a schematic diagram of the inlet isolation assembly of the inlet air path assembly of the present application; Figure 8 It is an assembly schematic diagram of the outlet air path assembly, the control unit and the emergency bypass assembly of the present application; Figure 9 It is a system diagram of the system of the present application applied to the coal mill unit.

[0014] In the figure: 1 - body of the air heater, 2 - inlet air path assembly, 3 - outlet air path assembly, 4 - control unit, 5 - emergency bypass assembly, 11 - heat exchange pipe group, 12 - steam inlet pipe, 13 - condensate outlet pipe, 14 - pulse purging mechanism, 141 - purging nozzle, 142 - pulse distributor, 143 - pulse valve, 15 - pressure sensor, 16 - tube sheet, 161 - honeycomb flow guide hole, 17 - ash discharge pipe, 21 - three-way air source pipe, 211 - electric flow guide baffle, 212 - servo motor, 22 - cyclone pre-separator, 23 - inlet isolation assembly, 231 - double gate aeration sealing isolation valve, 232 - pressure control valve, 233 - blowdown port, 24 - ash collector, 31 - outlet regulating assembly, 32 - flexible sealing section, 51 - bypass pipe, 52 - emergency cut-off valve, 53 - check valve. DETAILED DESCRIPTION

[0015] Example 1

[0016] As Figures 1 to 8As shown, the coal mill warm air system with isolation and anti-dust function provided by the present application adopts the technical scheme, which comprises a warm air heater body 1, an inlet air path assembly 2, an outlet air path assembly 3, a control unit 4 and an emergency bypass assembly 5; the inlet air path assembly 2 comprises a three-way air source pipe 21, a cyclone pre-separator 22 and an inlet isolation assembly 23 connected in series; two air inlet ports of the three-way air source pipe 21 are respectively used for connecting primary air mother pipes of units A and B, and an air outlet port of the three-way air source pipe 21 is in communication with an air inlet of the cyclone pre-separator 22; a bottom of the cyclone pre-separator 22 is provided with a dust hopper 24 with an electric dust discharge valve; an inlet of the inlet isolation assembly 23 is in sealed connection with an air outlet of the cyclone pre-separator 22, and an outlet is in communication with a primary air inlet of the warm air heater body 1 through a flange; a steam inlet of the warm air heater body 1 is connected with an auxiliary steam pipeline, and a condensate water outlet is connected with a drain pipeline; the outlet air path assembly 3 comprises an outlet adjusting assembly 31 and a flexible sealing section 32 connected in series; an inlet of the outlet adjusting assembly 31 is in communication with a primary air outlet of the warm air heater body 1; an outlet of the flexible sealing section 32 is used for connecting a coal mill mixed air pipeline; the control unit 4 is electrically connected with the inlet isolation assembly 23, the outlet adjusting assembly 31 and the electric dust discharge valve of the dust hopper 24 respectively, and is used for controlling operation states of the assemblies.

[0017] The warm air heater body 1 is internally provided with a heat exchange pipe group 11, the heat exchange pipe group 11 is composed of multiple layers of parallel arranged serpentine pipelines, a polytetrafluoroethylene anti-sticking coating layer is coated on a pipeline surface of the heat exchange pipe group 11, a coating layer thickness is 50-100 μm, a right side of the serpentine pipeline is respectively in communication with a steam inlet pipeline 12 vertically upwardly and penetrating through the warm air heater body, a left side of the serpentine pipeline is respectively in communication with a condensate water outlet pipeline 13 vertically downwardly and penetrating through the warm air heater body, and an upper side of the heat exchange pipe group 11 is provided with a pulse purging mechanism 14; the pulse purging mechanism 14 comprises multiple purging nozzles 141 arranged uniformly along a length direction of the heat exchange pipe group, and a pulse distributor 142 connected with the nozzles; the pulse distributor 142 is connected with a compressed air source through a pulse valve 143; the primary air inlets and outlets of the warm air heater body 1 are respectively provided with pressure sensors 15, two ends of the heat exchange pipe group 11 are connected with a shell of the warm air heater body 1 through a tube plate 16, a windward surface of the tube plate 16 is provided with honeycomb flow guiding holes 161, and a surface is sprayed with a tungsten carbide wear-resistant layer; a dust discharge pipe 17 with a solenoid valve is arranged at a bottom of the shell of the warm air heater body 1; the pressure sensors 15 are electrically connected with the control unit 4; and the control unit 4 controls opening and closing frequencies of the pulse valve according to pressure difference signals of the two pressure sensors.

[0018] The electric guide baffle 211 is connected to the servo motor 212 installed on the upper part of the pipe wall at the shaft end, and the servo motor 212 is electrically connected with the control unit 4; the inner wall of the three-way air source pipe 21 is coated with a wear-resistant ceramic coating, and a circular arc transition guide surface is arranged at the corner thereof.

[0019] The import isolation assembly 23 is a double-gate inflatable sealing isolation valve 231, a sealed gas cavity is formed between the double-gate inflatable sealing isolation valve 231, the sealed gas cavity is connected with an inert gas supply pipeline, and a pressure control valve 232 is arranged on the pipeline; a blowdown port 233 is arranged at the bottom of the valve cavity of the double-gate inflatable sealing isolation valve 231, the blowdown port 233 is communicated with the ash collector 24 through a pipeline, and an electromagnetic valve is arranged on the pipeline; the pressure control valve and the electromagnetic valve are electrically connected with the control unit 4.

[0020] The outlet adjusting assembly 31 is an intelligent electric regulating butterfly valve, the intelligent electric regulating butterfly valve is integrated with a flow detection module and a temperature feedback module, a detection probe of the temperature feedback module extends into the mixed air pipeline of the coal mill; the intelligent electric regulating butterfly valve is electrically connected with the control unit 4 through a PID controller, and the control unit 4 adjusts the opening degree of the intelligent electric regulating butterfly valve according to the mixed air temperature detected by the temperature feedback module.

[0021] The control unit 4 comprises a PLC main controller, a man-machine interactive terminal and a wireless transmission module; the PLC main controller is electrically connected with each actuator and sensor respectively, for receiving a detection signal and outputting a control instruction; the man-machine interactive terminal is used for displaying system operation parameters and supporting manual / automatic mode switching; the wireless transmission module is used for communicating with a unit DCS system, to realize remote monitoring and linkage control.

[0022] The emergency bypass assembly 5 comprises a bypass pipeline 51, one end of the bypass pipeline 51 is connected to the import air path pipeline between the cyclone pre-separator 22 and the import isolation assembly 23, and the other end is connected to the outlet air path pipeline between the outlet adjusting assembly 31 and the flexible sealing section 32; an emergency cut-off valve 52 and a check valve 53 are sequentially arranged on the bypass pipeline 51, the emergency cut-off valve 52 is electrically connected with the control unit 4, and the opening and closing state of the emergency cut-off valve 52 forms interlocking control with the import isolation assembly 23 and the outlet adjusting assembly 31.

[0023] The working principle of the application is as follows: the control unit 4 adjusts the electric guide baffle 211 of the three-way air source pipe 21 through the servo motor 212 according to the unit state, so that the air flow direction of the three-way air source pipe 21 is adjusted, and the air flow direction of the three-way air source pipe 21 is adjusted. Figure 9The air in the primary air mother pipe of A and B sides is introduced into the system through the air inlet pipe of the left end of the three-way air source pipe 21, the pipe wall wear-resistant coating and the circular arc flow guide surface reduce the resistance and wear; the primary air first enters the cyclone pre-separator 22 to separate dust to the dust collecting hopper 24 with a motor-driven dust valve, the control unit 4 regularly opens the dust valve and the exhaust port electromagnetic valve of the inlet isolation assembly 23 to discharge dust; the pretreated primary air enters the primary air heater body 1 through the double-gate inflatable sealing isolation valve 231, the pressure control valve 232 charges inert gas into the sealing gas cavity, the auxiliary steam is introduced into the heat exchange pipe group 11 through the steam inlet pipe 12, the high-efficiency heat exchange is realized through the serpentine pipe and the anti-sticking coating, the primary air after heating flows to the outlet, and the condensed water is discharged through the condensed water outlet pipe 13; the pressure sensor 15 at the inlet and outlet of the primary air heater body 1 detects the pressure difference, if the pressure difference exceeds the standard, the control unit 4 starts the pulse purging mechanism 14, and the pulse purging mechanism 14 blows away the accumulated dust through the pulse distributor 142 and the purging nozzle 141; the primary air after heating passes through the outlet adjusting assembly 31, the control unit 4 adjusts the opening degree of the butterfly valve through the PID controller according to the probe signal of the temperature feedback module of the outlet adjusting assembly 31 to stabilize the mixed air temperature, and finally connects the flexible sealing section 32 to the coal mill mixed air descending pipe; if the core component fails, the control unit 4 immediately interlocks to close the inlet isolation assembly 23 and the outlet adjusting assembly 31, opens the emergency shut-off valve 52 of the emergency bypass assembly 5, the primary air passes through the bypass pipe 51 and the check valve 53 to ensure continuous air supply, and the whole process operation parameters are monitored in real time by the control unit 4 and uploaded to the unit DCS system.

[0024] The electrical connection mode or structure not described in detail in the present application is prior art.

[0025] Although the specific embodiments of the present application have been described in detail above, the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application, and the modifications or changes without creative labor are still within the protection scope of the present application.

Claims

1. A coal mill air heating system with isolation and anti-dust functions, characterized in that, The air heater body (1), the inlet air path assembly (2), the outlet air path assembly (3) and the control unit (4) are included. The inlet air path assembly (2) includes a three-way air source pipe (21), a cyclone pre-separator (22) and an inlet isolation assembly (23) connected in series. Two air inlet ports of the three-way air source pipe (21) are used to connect the primary air mother pipe of the unit A and B respectively. The air outlet port is communicated with the air inlet of the cyclone pre-separator (22). The bottom of the cyclone pre-separator (22) is provided with a dust hopper (24) with a motor-driven dust valve. The inlet of the inlet isolation assembly (23) is sealingly connected with the air outlet of the cyclone pre-separator (22). The outlet is communicated with the primary air inlet of the air heater body (1) through a flange. The steam inlet of the air heater body (1) is connected with an auxiliary steam pipeline. The condensate outlet is connected with a drain pipeline. The outlet air path assembly (3) includes an outlet adjusting assembly (31) and a flexible sealing section (32) connected in series. The inlet of the outlet adjusting assembly (31) is communicated with the primary air outlet of the air heater body (1). The outlet of the flexible sealing section (32) is used to connect the coal mill mixed air pipeline. The control unit (4) is electrically connected with the inlet isolation assembly (23), the outlet adjusting assembly (31) and the motor-driven dust valve of the dust hopper (24) respectively, and is used to control the running state of each assembly.

2. The coal mill air heating system with the isolation and anti-dust functions according to claim 1, characterized in that, The inlet isolation assembly (23) is a double-gate inflatable sealing isolation valve (231). The double-gate inflatable sealing isolation valve (231) forms a sealed gas cavity. The sealed gas cavity is connected with an inert gas supply pipeline. A pressure control valve (232) is arranged on the pipeline. The bottom of the valve cavity of the double-gate inflatable sealing isolation valve (231) is provided with a blowdown port (233). The blowdown port (233) is communicated with the dust hopper (24) through a pipeline. An electromagnetic valve is arranged on the pipeline. The pressure control valve and the electromagnetic valve are electrically connected with the control unit (4).

3. The coal mill air heating system with the isolation and anti-dust functions according to claim 1, characterized in that, The air heater body (1) is internally provided with a heat exchange pipe group (11). The heat exchange pipe group (11) is composed of multiple layers of parallel arranged serpentine pipes. The pipe openings on the right side of the serpentine pipes are respectively communicated with the steam inlet pipeline (12) which vertically upwards and penetrates the air heater body. The pipe openings on the left side of the serpentine pipes are respectively communicated with the condensate outlet pipeline (13) which vertically downwards and penetrates the air heater body. The upper side of the heat exchange pipe group (11) is provided with a pulse purging mechanism (14). The pulse purging mechanism (14) includes multiple purging nozzles (141) arranged uniformly along the length direction of the heat exchange pipe group, and a pulse distributor (142) connected with the nozzles. The pulse distributor (142) is connected with a compressed air source through a pulse valve (143). The primary air inlets and outlets of the air heater body (1) are respectively provided with pressure sensors (15). The pressure sensors (15) are electrically connected with the control unit (4). The control unit (4) controls the opening and closing frequency of the pulse valve according to the pressure difference signals of the two pressure sensors.

4. The coal mill air heating system with the isolation and anti-dust functions according to claim 1, characterized in that, The outlet adjusting assembly (31) is an intelligent electric regulating butterfly valve, which is integrated with a flow detection module and a temperature feedback module, a detection probe of the temperature feedback module extends into a mixed air pipe of the coal mill; the intelligent electric regulating butterfly valve is electrically connected with the control unit (4) through a PID controller, and the control unit (4) adjusts the opening degree of the intelligent electric regulating butterfly valve according to the mixed air temperature detected by the temperature feedback module.

5. The system of claim 1, wherein the system further comprises a dustproof device. The electric guide baffle (211) is connected and installed on the upper part of the pipe wall through the shaft end of the servo motor (212), and the servo motor (212) is electrically connected with the control unit (4); the inner wall of the three-way air source pipe (21) is coated with a wear-resistant ceramic coating, and a circular arc transition guide surface is arranged at the corner thereof.

6. The coal mill air heating system with the isolation and anti-dust functions according to claim 1, characterized in that, The surface of the heat exchange pipe group (11) is coated with a polytetrafluoroethylene anti-sticking coating with a thickness of 50-100 μm; the two ends of the heat exchange pipe group (11) are connected with the shell of the air heater body (1) through the pipe plate (16), the windward surface of the pipe plate (16) is provided with a honeycomb guide hole (161), and the surface is sprayed with a tungsten carbide wear-resistant layer, and the bottom of the shell of the air heater body (1) is provided with an ash discharge pipe (17) with a solenoid valve.

7. The coal mill air heating system with the isolation and anti-dust functions according to claim 1, characterized in that, The emergency bypass assembly (5) includes a bypass pipe (51), one end of the bypass pipe (51) is connected to the inlet air duct between the cyclone pre-separator (22) and the inlet isolation assembly (23), and the other end is connected to the outlet air duct between the outlet adjusting assembly (31) and the flexible sealing section (32); the bypass pipe (51) is sequentially provided with an emergency shut-off valve (52) and a check valve (53), the emergency shut-off valve (52) is electrically connected with the control unit (4), and the opening and closing state of the emergency shut-off valve (52) is interlocked with the inlet isolation assembly (23) and the outlet adjusting assembly (31).

8. The coal mill air heating system with the isolation and anti-dust functions according to any one of claims 1 to 7, characterized in that, The control unit (4) includes a PLC main controller, a man-machine interaction terminal and a wireless transmission module; the PLC main controller is electrically connected with each actuator and sensor, for receiving detection signals and outputting control instructions; the man-machine interaction terminal is used for displaying system operating parameters and supporting manual / automatic mode switching; the wireless transmission module is used for communicating with the unit DCS system to realize remote monitoring and linkage control.

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