CN112604776A - Medium-speed roller type coal mill overhaul early warning device and method - Google Patents

Abstract

The utility model provides a medium speed roll-type coal pulverizer overhaul early warning device and method, it includes wind pressure early warning device, grinding roller early warning device and nozzle early warning device, the wind pipe through wind pressure early warning device and the primary air duct air intake connection of coal pulverizer, be located and set up the wind pressure sensor in the wind pipe, be connected with the mill of coal pulverizer through grinding roller early warning device, distance sensor's inductive head is towards the mill cover in the mill, weight sensor through nozzle early warning device is connected with the quiet ring of coal pulverizer, it is located the rotating ring one side of coal pulverizer to be connected the filter disc with weight sensor, restart distance sensor after sending the early warning through wind pressure sensor and weight sensor, automatic shutdown again overhaul when PLC control system sends out overhaul warning. The invention overcomes the problems that the wearing of the easily damaged parts of the original coal mill is asynchronous and the overhaul time of the coal mill cannot be accurately and reasonably determined, and has the characteristics of simple structure, online early warning of the easily damaged parts of the coal mill, contribution to accurately and reasonably determining the overhaul time of the coal mill and simple and convenient operation.

Description

Medium-speed roller type coal mill overhaul early warning device and method

Technical Field

The invention belongs to the technical field of coal mill maintenance, and relates to an early warning device and method for overhaul of a medium-speed roller type coal mill.

Background

In a large coal-fired power station, coal blocks are ground into powder by a coal mill and then mixed with other mixtures, and the mixture is conveyed to a coal-fired furnace to improve the combustion efficiency and reduce the fuel cost. The coal mill is divided into a high speed, a medium speed and a low speed according to the speed, wherein the medium speed coal mill is related to the medium speed coal mill, three grinding rollers are distributed on a grinding disc roller path along the circumferential direction, the grinding force is generated by a hydraulic loading system and is controlled by a PLC control system, and as the number of easily damaged parts of the coal mill is large, the coal mill is mainly reflected in that the air pressure is insufficient due to air leakage of a primary air inlet, and flying dust from an air preheater is carried to cause flying and diffusion; secondly, after the grinding roller and the grinding disc are seriously abraded, the thickness of the coal seam is changed due to overlarge gap, and the output force is abnormal; in addition, after the nozzles between the static ring and the moving ring are abraded too much, the pebble coal powder carried by the coal hopper is granular and scattered around the static ring. The wearing parts cannot accurately and reasonably determine the overhaul time of the coal mill due to the asynchronous loss.

Disclosure of Invention

The invention aims to solve the technical problem of providing a medium-speed roller type coal mill overhaul early warning device and a method, the device and the method are simple in structure, an air pipe adopting a wind pressure early warning device is connected with an air inlet of a primary air duct of the coal mill, a wind pressure sensor is arranged in the air pipe, the grinding roller early warning device is connected with a grinding disc of the coal mill, a sensing head of a distance sensor faces a grinding sleeve in the grinding disc, a weight sensor of a nozzle early warning device is connected with a static ring of the coal mill, a filter disc connected with the weight sensor is arranged on one side of a movable ring of the coal mill, the distance sensor is started after the wind pressure sensor and the weight sensor give out early warning, the device and the method automatically stop and then overhaul after a PLC control system gives out overhaul warning, main easily damaged parts of the coal mill are early warned on line, the.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: an early warning device for overhaul of a medium-speed roller type coal mill comprises a wind pressure early warning device, a grinding roller early warning device and a nozzle early warning device; the utility model discloses a pneumatic early warning device, including mill, wind pressure early warning device, nozzle early warning device, mill, distance sensor, filter disc, pneumatic sensor, distance sensor and weight sensor, wind pressure early warning device's tuber pipe and the wind channel air intake connection of the one time of coal pulverizer are located the tuber pipe and set up wind pressure sensor, the mill of mill roller early warning device and coal pulverizer is connected, distance sensor's inductive head is towards the mill cover in the mill, nozzle early warning device's weighing transducer is connected with the quiet ring of coal pulverizer, be located rotating ring one side of coal pulverizer with weighing transducer connection filter disc.

The grinding roller early warning device comprises a sealing cover hinged to one side of the distance sensor and an electric push rod connected with the sealing cover.

The nozzle early warning device comprises a filter disc connected with the weight sensor, and the filter disc is positioned on one side of the nozzle on the movable ring.

The bottom of the filter disc is provided with filter holes which are uniformly and densely distributed.

The wind pressure sensor senses the wind pressure in the primary air duct of the coal mill and transmits the wind pressure to the PLC control system, and when the wind pressure is lower than a set value, a wind pressure early warning is sent out.

The distance sensor senses the change of the distance between the grinding disc and the grinding sleeve, transmits data to the PLC control system, and sends out distance early warning when the distance is larger than a set value.

The weight sensor senses the weight of the granular coal powder in the filter disc, transmits data to the PLC control system, and sends out weight early warning when the weight is larger than a set value.

And the PLC control system sends out overhaul alarm when wind pressure early warning, distance early warning and weight early warning simultaneously appear.

The early warning method of the early warning device for the overhaul of the medium-speed roller type coal mill comprises the following steps:

s1, when the PLC control system sends out a wind pressure early warning and a weight early warning at the same time, the electric push rod is closed, the telescopic end of the electric push rod retracts to pull the sealing cover to be opened, at the moment, the distance sensor works, and the sensing head is exposed out of the distance between the sensing grinding disc and the grinding sleeve;

s2, when the distance between the grinding disc and the grinding sleeve is smaller than the set distance, the PLC control system does not send out distance early warning; when the distance between the grinding disc and the grinding sleeve is larger than the set distance, the PLC control system sends out distance early warning, meanwhile, the PLC control system sends out overhaul alarm to control the coal grinding machine to stop, and then the coal grinding machine needs to enter overhaul.

An early warning device for overhaul of a medium-speed roller type coal mill comprises a wind pressure early warning device, a grinding roller early warning device and a nozzle early warning device; the wind pipe of wind pressure early warning device and the wind intake connection of the wind channel of coal pulverizer are located and set up wind pressure sensor in the wind pipe, grinding roller early warning device is connected with the mill of coal pulverizer, distance sensor's inductive head is towards the mill cover in the mill, nozzle early warning device's weighing transducer is connected with the quiet ring of coal pulverizer, it is located rotating ring one side of coal pulverizer to be connected the filter disc with weighing transducer, wind pressure sensor, distance sensor and weighing transducer are connected with the PLC control system of coal pulverizer. Simple structure, during the use, wind pipe through wind pressure early warning device and the primary air channel air intake connection of coal pulverizer, be located and set up wind pressure sensor in the tuber pipe, be connected with the mill of coal pulverizer through grinding roller early warning device, distance sensor's inductive head is towards the mill cover in the mill, weight sensor through nozzle early warning device is connected with the quiet ring of coal pulverizer, it is located rotating ring one side of coal pulverizer to be connected the filter disc with weight sensor, send out the early warning through wind pressure sensor and weight sensor and start distance sensor again, send out after overhaul warning auto-stop and carry out the overhaul again when PLC control system, online early warning coal pulverizer essential part, be favorable to accurately rationally confirming the time of coal pulverizer overhaul, easy operation is convenient.

In a preferred scheme, the grinding roller early warning device comprises a sealing cover hinged to one side of the distance sensor and an electric push rod connected with the sealing cover. Simple structure, during the use, the sealed switching that covers of electric putter drive, sealed lid open back distance sensor's inductive head towards the mill cover in the mill, respond to the mill and grind the distance between the cover.

Preferably, the electric push rod is connected with the PLC control system, and the work of the electric push rod is controlled by the PLC control system.

Preferably, when the PLC control system sends out wind pressure early warning and weight early warning, just open sealed lid after, distance sensor just begins to work, and its aim at avoids buggy to cover distance sensor's probe and causes the measurement inaccurate.

In a preferred scheme, the nozzle early warning device comprises a filter disc connected with the weight sensor, and the filter disc is positioned on one side of the nozzle on the movable ring. The coal ash conveying device has the advantages that the structure is simple, during use, coal ash discharged from a nozzle of the coal mill enters the coal ash conveying line, and after the nozzle gap is too large, the coal ash is scattered around a static ring of the coal mill and falls into the filter disc.

In a preferred scheme, the bottom of the filter disc is provided with uniformly and densely distributed filter holes. Simple structure, during the use, after scattered coal ash fell into the filter disc, finer coal ash passed the filtration pore of filter disc and fell into on the quiet ring of coal pulverizer, heavier coal ash granule was blockked in the filter disc by the filtration pore.

Preferably, the fine coal ash falling into the static ring of the coal mill is cleaned at intervals, and the situation that the filter holes of the filter disc are blocked after accumulation is avoided, so that the filter disc loses the filtering function and the measurement is inaccurate is avoided.

In the preferred scheme, the wind pressure sensor senses the wind pressure in the primary air duct of the coal mill and transmits the wind pressure to the PLC control system, and when the wind pressure is lower than a set value, a wind pressure early warning is sent out. Simple structure, during the use, after the wind channel air inlet, with the work of the wind pressure sensor in the tuber pipe of its UNICOM, the on-line measurement wind pressure, send out the wind pressure early warning when the wind pressure is less than the setting value, early warning information is shown on PLC control system's display screen.

In an optimal scheme, the distance sensor senses the change of the distance between the grinding disc and the grinding sleeve, transmits data to the PLC control system, and sends out distance early warning when the distance is greater than a set value. Simple structure, during the use, when grinding the cover wearing and tearing when too big, grind the outer wall of cover and the increase in inner wall clearance of mill, at this moment, mill and distance sensor's distance changes, sends the distance early warning when distance that distance sensor sensed is greater than the setting value, and early warning information is shown on PLC control system's display screen.

In the preferred scheme, the weight sensor senses the weight of the granular coal powder in the filter disc, transmits data to the PLC control system, and sends out weight early warning when the weight is greater than a set value. Simple structure, during the use, more tiny coal ash is filtered the back, and thicker fly ash overflow is in the filter disc, and its weight is more and more heavy along with the accumulation of time, sends the weight early warning when weight sensor senses weight and is greater than the setting value, and early warning information is shown on PLC control system's display screen.

In the preferred scheme, the PLC control system sends out overhaul alarm when wind pressure early warning, distance early warning and weight early warning appear simultaneously. Simple structure, during the use, only when wind pressure early warning, distance early warning and weight early warning take place simultaneously, PLC control system just sends the overhaul warning to control the coal pulverizer and shut down.

In a preferred scheme, the early warning method of the early warning device for the overhaul of the medium-speed roller coal mill comprises the following steps:

s1, when the PLC control system sends out a wind pressure early warning and a weight early warning at the same time, the electric push rod is closed, the telescopic end of the electric push rod retracts to pull the sealing cover to be opened, at the moment, the distance sensor works, and the sensing head is exposed out of the distance between the sensing grinding disc and the grinding sleeve;

s2, when the distance between the grinding disc and the grinding sleeve is smaller than the set distance, the PLC control system does not send out distance early warning; when the distance between the grinding disc and the grinding sleeve is larger than the set distance, the PLC control system sends out distance early warning, meanwhile, the PLC control system sends out overhaul alarm to control the coal grinding machine to stop, and then the coal grinding machine needs to enter overhaul. The method is simple and convenient to operate, determines the reasonable time for overhauling the main wearing parts on line and sends out an overhaul alarm.

The utility model provides a medium speed roll-type coal pulverizer overhaul early warning device and method, it includes wind pressure early warning device, grinding roller early warning device and nozzle early warning device, the wind pipe through wind pressure early warning device and the primary air duct air intake connection of coal pulverizer, be located and set up the wind pressure sensor in the wind pipe, be connected with the mill of coal pulverizer through grinding roller early warning device, distance sensor's inductive head is towards the mill cover in the mill, weight sensor through nozzle early warning device is connected with the quiet ring of coal pulverizer, it is located the rotating ring one side of coal pulverizer to be connected the filter disc with weight sensor, restart distance sensor after sending the early warning through wind pressure sensor and weight sensor, automatic shutdown again overhaul when PLC control system sends out overhaul warning. The invention overcomes the problems that the wearing of the easily damaged parts of the original coal mill is asynchronous and the overhaul time of the coal mill cannot be accurately and reasonably determined, and has the characteristics of simple structure, online early warning of the easily damaged parts of the coal mill, contribution to accurately and reasonably determining the overhaul time of the coal mill and simple and convenient operation.

Drawings

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

fig. 1 is a schematic structural diagram of a wind pressure warning device according to the present invention.

Fig. 2 is a front view of fig. 1.

Fig. 3 is a schematic structural diagram of the early warning device for the grinding roller of the invention.

Fig. 4 is a front view of fig. 3.

Fig. 5 is a schematic top view of fig. 3.

Fig. 6 is a schematic structural view of the distance sensor of the present invention.

Fig. 7 is a schematic cross-sectional view taken at a-a of fig. 6.

Fig. 8 is a schematic structural diagram of the nozzle warning device of the present invention.

Fig. 9 is a front view of fig. 8.

FIG. 10 is a diagram of the loading transmission system of the coal pulverizer of the present invention.

FIG. 11 is a schematic view of the internal structure of the coal pulverizer of the present invention.

FIG. 12 is a graph of the air-coal ratio of the coal mill of the present invention.

In the figure: the device comprises a wind pressure early warning device 1, an air pipe 11, a wind pressure sensor 12, a grinding roller early warning device 2, a distance sensor 21, a sealing cover 22, an electric push rod 23, a nozzle early warning device 3, a weight sensor 31 and a filter disc 32.

Detailed Description

As shown in fig. 1 to 12, an early warning device for overhaul of a medium-speed roller type coal mill comprises a wind pressure early warning device 1, a grinding roller early warning device 2 and a nozzle early warning device 3; wind pressure early warning device 1's tuber pipe 11 and the wind channel air intake connection of the primary duct of coal pulverizer, be located and set up wind pressure sensor 12 in the tuber pipe 11, grinding roller early warning device 2 is connected with the mill of coal pulverizer, distance sensor 21's inductive head is towards the mill cover in the mill, nozzle early warning device 3's weighing transducer 31 is connected with the quiet ring of coal pulverizer, it is located movable ring one side of coal pulverizer to be connected filter disc 32 with weighing transducer 31, wind pressure sensor 12, distance sensor 21 and weighing transducer 31 are connected with the PLC control system of coal pulverizer. Simple structure, during the use, wind pipe 11 through wind pressure early warning device 1 and the primary air channel air intake connection of coal pulverizer, be located and set up wind pressure sensor 12 in wind pipe 11, be connected with the mill of coal pulverizer through grinding roller early warning device 2, distance sensor 21's inductive head is towards the mill cover in the mill, weight sensor 31 through nozzle early warning device 3 is connected with the quiet ring of coal pulverizer, it is located rotating ring one side of coal pulverizer to be connected filter disc 32 with weight sensor 31, send out after the early warning restart distance sensor 21 through wind pressure sensor 12 and weight sensor 31, send out after the overhaul warning auto-stop to overhaul again and overhaul when PLC control system, online early warning coal pulverizer mainly easily decreases the part, be favorable to accurate reasonable definite coal pulverizer overhaul's time, easy operation is convenient.

In a preferred scheme, the grinding roller early warning device 2 comprises a sealing cover 22 hinged to one side of the distance sensor 21 and an electric push rod 23 connected with the sealing cover 22. Simple structure, during the use, the sealed 22 switching of electric putter 23 drive, sealed 22 back of opening of lid distance sensor 21's inductive head is towards the mill cover in the mill, response mill and the distance between the mill cover.

Preferably, the electric push rod 23 is connected with a PLC control system, and the work of the electric push rod is controlled by the PLC control system.

Preferably, when the PLC control system sends out the wind pressure warning and the weight warning, the distance sensor 21 starts to work after the sealing cover 22 is opened, which aims to avoid inaccurate measurement caused by the pulverized coal covering the probe of the distance sensor 21.

In a preferred scheme, the nozzle early warning device 3 comprises a filter disc 32 connected with the weight sensor 31, and the filter disc 32 is positioned on one side of the nozzle on the movable ring. Simple structure, during the use, coal ash that the coal pulverizer nozzle was discharged gets into the coal ash transfer chain, and when the nozzle clearance was too big back, coal ash scatters around the coal pulverizer stationary ring, falls into in the filter disc 32.

In a preferred scheme, the bottom of the filter disc 32 is provided with filter holes which are uniformly and densely distributed. Simple structure, during the use, after the scattered coal ash fell into filter plate 32, finer coal ash passed filter disc 32's filtration pore and fell into on the coal pulverizer stationary ring, and heavier coal ash granule is blockked in filter plate 32 by the filtration pore.

Preferably, the fine coal ash falling on the static ring of the coal mill is cleaned at intervals, so that the filter holes of the filter disc 32 are prevented from being blocked after being accumulated, and the filter disc 32 loses the filtering function to cause inaccurate measurement.

In the preferred scheme, the wind pressure sensor 12 senses the wind pressure in the primary air duct of the coal mill and transmits the wind pressure to the PLC control system, and when the wind pressure is lower than a set value, a wind pressure early warning is sent out. Simple structure, during the use, after the wind channel air inlet, with the work of wind pressure sensor 12 in the tuber pipe 11 of its UNICOM, the on-line measurement wind pressure, send out the wind pressure early warning when the wind pressure is less than the setting value, early warning information is shown on PLC control system's display screen.

In the preferred scheme, the distance sensor 21 senses the distance change between the grinding disc and the grinding sleeve, transmits data to the PLC control system, and sends out distance early warning when the distance is greater than a set value. Simple structure, during the use, when grinding the cover wearing and tearing when too big, grind the outer wall of cover and the increase in inner wall clearance of mill, at this moment, mill and distance sensor 21's distance changes, sends the distance early warning when distance that distance sensor 21 sensed is greater than the setting value, and early warning information is shown on PLC control system's display screen.

In the preferred scheme, the weight sensor 31 senses the weight of the granular coal powder in the filter disc 32, transmits data to the PLC control system, and sends out weight early warning when the weight is greater than a set value. Simple structure, during the use, more tiny coal ash is filtered the back, and thicker fly ash overflow is in filter plate 32, and its weight is more and more heavy along with the accumulation of time, sends out weight early warning when weight sensor 31 senses weight and is greater than the setting value, and early warning information is shown on PLC control system's display screen.

In the preferred scheme, the PLC control system sends out overhaul alarm when wind pressure early warning, distance early warning and weight early warning appear simultaneously. Simple structure, during the use, only when wind pressure early warning, distance early warning and weight early warning take place simultaneously, PLC control system just sends the overhaul warning to control the coal pulverizer and shut down.

In a preferred embodiment, the method for warning the overhaul of the medium speed roller coal mill comprises the following steps:

s1, when the PLC control system simultaneously sends out a wind pressure early warning and a weight early warning, the electric push rod 23 is closed, the telescopic end of the electric push rod 23 retracts to pull the sealing cover 22 to be opened, at the moment, the distance sensor 21 works, and the sensing head is exposed out of the distance between the sensing grinding disc and the grinding sleeve;

s2, when the distance between the grinding disc and the grinding sleeve is smaller than the set distance, the PLC control system does not send out distance early warning; when the distance between the grinding disc and the grinding sleeve is larger than the set distance, the PLC control system sends out distance early warning, meanwhile, the PLC control system sends out overhaul alarm to control the coal grinding machine to stop, and then the coal grinding machine needs to enter overhaul. The method is simple and convenient to operate, determines the reasonable time for overhauling the main wearing parts on line and sends out an overhaul alarm.

When the device and the method are installed and used, an air pipe 11 of the air pressure early warning device 1 is connected with an air inlet of a primary air channel of the coal mill, an air pressure sensor 12 is arranged in the air pipe 11, a grinding roller early warning device 2 is connected with a grinding disc of the coal mill, a sensing head of a distance sensor 21 faces a grinding sleeve in the grinding disc, a weight sensor 31 of a nozzle early warning device 3 is connected with a static ring of the coal mill, a filter disc 32 connected with the weight sensor 31 is located on one side of a movable ring of the coal mill, the distance sensor 21 is started after the air pressure sensor 12 and the weight sensor 31 give out early warning, the device is automatically stopped and overhauled after a PLC control system gives out an overhauled warning, main easily-damaged parts of the coal mill are early warned on line, the time for overhauling the coal mill can be accurately and reasonably determined.

During the use, electric putter 23 drive sealed 22 switching, and sealed 22 is opened back distance sensor 21's inductive head and is towards the mill cover in the mill, responds to the distance between mill dish and the mill cover.

When the coal ash filter is used, coal ash discharged from a nozzle of the coal mill enters the coal ash conveying line, and when the nozzle clearance is too large, the coal ash is scattered around a static ring of the coal mill and falls into the filter disc 32.

When the coal dust collector is used, after scattered coal dust falls into the filter disc 32, the smaller coal dust passes through the filter holes of the filter disc 32 and falls onto the static ring of the coal mill, and the heavier coal dust particles are blocked in the filter disc 32 by the filter holes.

When the wind pressure early warning device is used, after air enters a primary air duct, the wind pressure sensor 12 in the air duct 11 communicated with the primary air duct works to measure wind pressure on line, and when the wind pressure is lower than a set value, a wind pressure early warning is sent out, and early warning information is displayed on a display screen of a PLC control system.

During the use, when grinding the cover wearing and tearing when too big, grind the outer wall of cover and the increase of the inner wall clearance of mill, at this moment, mill and distance sensor 21's distance changes, sends the distance early warning when distance that distance sensor 21 sensed is greater than the setting value, and early warning information is shown on PLC control system's display screen.

When the device is used, after the fine coal ash is filtered, the coarse coal ash overflows into the filter disc 32, the weight of the coarse coal ash is heavier and heavier along with the accumulation of time, when the weight sensor 31 senses that the weight is larger than a set value, a weight early warning is sent, and early warning information is displayed on a display screen of the PLC control system.

When the coal mill is used, only when the wind pressure early warning, the distance early warning and the weight early warning occur simultaneously, the PLC control system sends out the overhaul alarm and controls the coal mill to stop.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and features in the embodiments and examples in the present application may be arbitrarily combined with each other without conflict. The protection scope of the present invention is defined by the claims, and includes equivalents of technical features of the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.

Claims (9)

1. The utility model provides a medium speed roll-type coal pulverizer overhaul early warning device which characterized by: the device comprises a wind pressure early warning device (1), a grinding roller early warning device (2) and a nozzle early warning device (3); air pipe (11) of wind pressure early warning device (1) and the primary air channel air intake connection of coal pulverizer, be located and set up wind pressure sensor (12) in air pipe (11), grinding roller early warning device (2) are connected with the mill dish of coal pulverizer, the inductive head of distance sensor (21) is towards the mill cover in the mill dish, weight sensor (31) of nozzle early warning device (3) are connected with the quiet ring of coal pulverizer, be connected filter disc (32) with weight sensor (31) and be located rotating ring one side of coal pulverizer, wind pressure sensor (12), distance sensor (21) and weight sensor (31) are connected with the PLC control system of coal pulverizer.

2. The medium speed roller mill overhaul early warning device of claim 1, which is characterized in that: the grinding roller early warning device (2) comprises a sealing cover (22) hinged to one side of the distance sensor (21) and an electric push rod (23) connected with the sealing cover (22).

3. The medium speed roller mill overhaul early warning device of claim 1, which is characterized in that: the nozzle early warning device (3) comprises a filter disc (32) connected with the weight sensor (31), and the filter disc (32) is located on one side of the nozzle on the movable ring.

4. The medium speed roller mill overhaul early warning device of claim 1, which is characterized in that: the bottom of the filter disc (32) is provided with filter holes which are uniformly and densely distributed.

5. The medium speed roller mill overhaul early warning device of claim 1, which is characterized in that: the wind pressure sensor (12) senses the wind pressure in the primary air duct of the coal mill and transmits the wind pressure to the PLC control system, and when the wind pressure is lower than a set value, a wind pressure early warning is sent out.

6. The medium speed roller mill overhaul early warning device of claim 1, which is characterized in that: the distance sensor (21) senses the distance change between the grinding disc and the grinding sleeve, transmits data to the PLC control system, and sends out distance early warning when the distance is larger than a set value.

7. The medium speed roller mill overhaul early warning device of claim 1, which is characterized in that: the weight sensor (31) senses the weight of the granular coal powder in the filter disc (32), transmits data to the PLC control system, and sends out weight early warning when the weight is larger than a set value.

8. The medium speed roller mill overhaul early warning device of claim 1, which is characterized in that: and the PLC control system sends out overhaul alarm when wind pressure early warning, distance early warning and weight early warning simultaneously appear.

9. The surveying method of the early warning device for the overhaul of the medium speed roller type coal mill according to any one of claims 1 to 8, which is characterized by comprising the following steps:

s1, when the PLC control system simultaneously sends out a wind pressure early warning and a weight early warning, the electric push rod (23) is closed, the telescopic end of the electric push rod (23) retracts to pull the sealing cover (22) to be opened, at the moment, the distance sensor (21) works, and the sensing head is exposed out of the distance between the sensing grinding disc and the grinding sleeve;

s2, when the distance between the grinding disc and the grinding sleeve is smaller than the set distance, the PLC control system does not send out distance early warning; when the distance between the grinding disc and the grinding sleeve is larger than the set distance, the PLC control system sends out distance early warning, meanwhile, the PLC control system sends out overhaul alarm to control the coal grinding machine to stop, and then the coal grinding machine needs to enter overhaul.

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