JPH03275152A - Abnormality detector for coal grinding mill - Google Patents

Abstract

PURPOSE:To definitely detect the origin of abnormality by providing a position detector for detecting the abnormal variations in the distance between the set positions of the grinding ring and grinding roller and furnishing an alarm or an indicating means. CONSTITUTION:The position detectors 18, 19 and 20 are set at the three positions in a mill housing 6. When the coal to be ground or foreign matter is supplied between the grinding ring 3 and the grinding roller 7, the gap between the rollers 3 and 7 are expanded, and pressure frames 11 are raised at each position. The gap between the rollers 3 and 7 is measured by measuring the positions of the raised frames, and the measured values are compared to detect the abnormal condition. The mill is appropriately and continuously operated in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an abnormality detection system for a coal crushing mill, and in particular, a system for detecting abnormalities in a coal crushing mill at an early stage and inspecting and repairing the mill. The present invention relates to an abnormality detection device for a coal crushing mill suitable for.

[Conventional technology]

For information on monitoring abnormalities in conventional mills that crush coal, etc., see Thermal and Nuclear Power Generation, Vol. 31, No. 6 (January 1980), pp. 29 to 39, or Hitachi Hyoron, No. 62.
Vol., No. 4 (April 1980), pp. 69 to 74, when detecting mill abnormalities, mill differential pressure, vibration, motor current value, etc. during mill operation are used. The value of the mill was detected, and abnormalities in the mill were detected from changes in that value.

[Problem to be solved by the invention]

As mentioned above, there are some differences in coal crushing mills in the prior art. There was the following problem.

(1) If the mill abnormality has not expanded, the mill differential pressure
Since it does not appear as a clear change in numerical values such as vibration or motor current value, by the time an abnormality is discovered, the mill has already suffered major damage or breakage.

(2) It is difficult to identify abnormal parts of the mill, and the parts to be repaired cannot be clearly identified.

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems in the conventional technology, and have found that the distance relationship between the grinding ring of the mill and the grinding roller, which indicates the most direct state of coal grinding, can be determined using a position detection sensor. We have discovered a method for early detection of abnormalities in the mill using the detection signal from this sensor.

An object of the present invention is to solve the problems in the prior art described above, and to improve the distance relationship between the coal crushing ring and the crushing roller in a coal crushing mill by providing at least three or more predetermined positions. By constantly monitoring with a position detector and processing the signals from the position detector,
The object of the present invention is to provide an abnormality detection device for a coal crushing mill that is provided with an abnormality detection means that (1) clearly detects the cause of the abnormality and (2) specifies the abnormal site.

[Means to solve the problem]

In order to further achieve the above object of the present invention, the distance relationship between a crushing ring for crushing coal and a crushing roller in a coal crushing mill is determined at at least three positions in the rotational direction of the crushing ring using a position detector. A detection means is provided which constantly monitors the mill and compares or synthesizes the position signals detected by these position detectors to determine the abnormality part of the mill and the nature of the abnormality.

The present invention includes a plurality of spherical or roller-shaped crushing rollers and a race-like or ring-shaped rotary crushing ring,
In a coal pulverizing mill having a function of pressurizing and pulverizing coal by the pulverizing roller and pulverizing ring and supplying the generated pulverized coal to a burner, variation in the distance between the pulverizing ring and the pulverizing roller at a set point is provided. This is an abnormality detection device for a coal crushing mill, in which position detectors are installed at at least three positions to constantly measure and detect abnormalities.

Further, in the coal crushing mill abnormality detection device of the present invention,
By comparing and calculating the signals input from position detectors installed at multiple positions within the mill with the signal values under normal conditions of the coal crushing mill, abnormal conditions of the coal crushing mill are detected early and an alarm is issued. Alternatively, a means for displaying the information may be provided.

In the coal crushing mill equipped with the abnormality detection device of the present invention, the position at which the variation in distance between the crushing ring and the crushing roller is measured at the set point between the crushing ring and the crushing roller is located at the top of the crushing roller. Preferably, the position is on the provided pressure frame and corresponds to each grinding roller.

[Effect]

In a coal crushing mill that has a rotating crushing ring and a crushing roller that rotates under pressure on the crushing ring, the coal fed into the mill is sandwiched between the crushing ring and the crushing roller and pressurized. and crushed. The pulverized coal is airflow conveyed to the outside of the mill along with pressurized air, but when the coal is pulverized, a layer of pulverized coal is formed between the pulverizing ring and the pulverizing rollers, so the pulverizing ring The distance between the grinding roller and the grinding roller changes by a predetermined interval.

On the other hand, if an abnormality occurs in the crushing roller or the crushing ring, or if there are foreign substances such as stones that cannot be crushed in the coal, the distance relationship between the crushing ring and the crushing roller can be detected at three or more locations. Signals with different phases are detected from the position detector provided at the position. By comparing and analyzing this signal with the signal during normal mill operation, it is possible to detect an abnormal state of the coal crushing mill.

〔Example〕

An embodiment of the present invention will be described below in more detail based on the drawings.

Before describing the features of the coal crushing mill provided with the abnormality detection device of the present invention, the structure of a conventional mill will be explained.

FIG. 5 shows an example of the structure of a typical conventional coal crushing mill. In the figure, the yoke 13 is driven through a gear box 14 provided at the bottom of the mill.
The grinding ring 3 installed in the section performs a rotational movement. A plurality of crushing rollers 7 are installed on the top of the crushing ring 3, and the crushing roller 7 itself is fixed to a pressure frame 11 provided on the top of the crushing roller rough, and the pressure frame 11 is a spring frame. 12
Pressure is applied to the crushing roller 7 toward the crushing ring 3 from above.

Coal introduced from the inlet of the coal feed pipe 1 flows between the pulverizing ring 3 and the pulverizing roller rough due to the rotational force of the entire yoke 13, and is pressurized and pulverized. The pulverized coal is conveyed by air flow together with the air introduced from the primary air duct 5, passes through the classifier 9, and is sent from the pulverized coal pipe 10 provided at the upper part of the mill housing 6 to the burner section of the furnace. supplied to

On the other hand, in the coal crushing mill having the structure shown in FIG. . Since it is necessary to apply pressure evenly to the crushing roller 7 provided in the mill, the pressurizing means is installed at at least three positions at equal intervals in the circumferential direction of the mill.

FIG. 1(a) shows an example of the structure of a coal pulverizing mill provided with the abnormality detection device of the present invention in contrast to the conventional coal pulverizing mill described above. Note that FIG. 1(b) is a view taken along arrow A in FIG. 1(a). In the figure, position detectors 9 and 20 for the pressure frame 11 are installed at three locations at equal intervals in the mill housing 6, and the signals detected by these position detectors are transmitted to the set normal state. A signal comparator that compares signals with signals during operation; an abnormality determination unit that determines abnormalities such as abnormal parts or positions of the mill as a result of comparing the signals; and an abnormality determination unit that determines abnormalities in the mill and issues an alarm or display. It consists of an abnormality signal output section that issues signals such as notifications or mill operation stoppages.

The operating principle of the position detector of the coal crushing mill exemplified in this embodiment is shown in FIGS. 2(a) and 2(b).

That is, when coal to be crushed or foreign matter 21 is inserted between the crushing ring 3 and the crushing roller 7, the gap between the crushing ring 3 and the crushing roller 7 widens, so that the position of the pressure frame 11 changes. rises at each position [Fig. 2(b)]. By measuring this raised position 8, the gap between the crushing ring 3 and the crushing roller 7, that is, the gap in the normal state when the coal is crushed, or the gap when foreign matter that is not crushed is mixed in. can be measured, and abnormal conditions can be detected by comparing them. In addition, by measuring the state when no coal is being introduced, that is, when there is no gap [Fig. 2 (a)], and comparing it with the initial state, the total amount of wear on the grinding roller 7 and the grinding ring 3 can be determined. measurement becomes possible.

In the coal crushing mill shown in this example, the crushing ring 3
Specifically, by measuring at three points at equal intervals in the rotation direction of the mill, it becomes possible to detect abnormalities in the mill as described below. Note that the abnormality detection shown below is a case where measurement is performed at the position of the crushing roller.

(1) Detection of foreign matter contamination other than coal, that is, when a substance that is difficult to crush (stone, iron, etc.) is mixed in and caught between the crushing ring 3 and the crushing roller 7, the position detector a ,b,
As shown in Fig. 3, the position signal from Q has a fairly sharp peak at the position where the foreign object is bitten, and this peak occurs in synchronization with the rotation of the crushing ring 3, so it is difficult to identify the position where the foreign object is present. can be detected.

(2) Detecting the deviation of the coal seam on the crushing ring 3, that is, as shown in FIG. 4, when a large amount of coal is caught between the crushing ring 3 and the crushing roller 7, the position detector at that part a.

As shown in Fig. 4, the position signals from b and c have gentle mountain-like peaks in areas where the coal seam is thick.
Since this occurs in synchronization with the rotation of the coal, it is possible to detect the position where a large amount of coal is trapped.

(3) Detection of the amount of coal on the crushing ring. This is detected as an absolute amount at the coal level detection position, and its accuracy is further improved by comparison (calibration) with the case where no coal is inserted. I can do it.

By directly measuring the amount of coal, it is possible to detect changes in grindability HGI (hard grindability) by comparing the coal levels when the same amount of coal is fed (different types of coal), and when there is no coal in the coal grinding mill. This makes it possible to detect idle running. Furthermore, (4) Detection of an abnormality in the crushing roller, which means that if there is an abnormality in the crushing roller, noise inherent to the position detectors a, b, and c provided at positions corresponding to the crushing roller (noise synchronized with the rotation of the crushing roller) is generated, so it is possible to detect an abnormality in the roller.

In the above embodiment, the position of the pressure frame is detected at the position (3) corresponding to each crushing roller position.
However, by installing position detectors at other locations within the mill, or by increasing or decreasing the number of position detectors installed, a means to more accurately detect abnormal conditions in the mill may be provided. Needless to say, this is within the technical scope of the present invention.

〔Effect of the invention〕

1. As explained in detail above, the position detector installed in the coal crushing mill of the present invention makes it possible to detect abnormalities in the crushing ring, crushing rollers, etc. at an early stage, thereby preventing the occurrence of mill troubles. This allows us to respond quickly and prevent major damage or breakage.

Furthermore, compared to conventional detection methods based on mill vibration, sound, or changes in motor current value, it is possible to accurately detect abnormalities and their causes, making maintenance and inspection of the mill extremely easy. Furthermore, the coal crushing mill equipped with the position detector of the present invention can detect the properties of the coal to be crushed (HG
I) is also possible, and since this HGI can be measured, it is also possible to calculate the pulverized coal particle size at the mill outlet, and the characteristics of the coal crushing mill can be accurately grasped and proper operation can be continued.

[Brief explanation of drawings]

FIG. 1(a) is a schematic diagram showing an example of the configuration of a mill abnormality detection device exemplified in an embodiment of the present invention, and FIG. 1(b)
2(a) and 2(b) are schematic diagrams showing the basic operation of the position detector illustrated in the embodiment of the present invention, and FIGS. FIG. 4 is a graph showing an example of the shape of a position signal from a position detector exemplified in the embodiment of the present invention, and FIG. 5 is a schematic diagram showing an example of the structure of a typical conventional roller-type coal crushing mill. be. 1...Coal feed pipe 3...Crushing ring 5...1
Secondary air duct 6... Mill housing 7... Grinding roller 9 - Classifier 10... Pulverized coal pipework 1... Pressure frame 12... Spring frame 13... Yoke 14... Gear box 15・
... Loading arm 16 ... Spring 17 ... Pressure cylinder 18
...Position detector (a) 19...Position detector (b) 20...Position detector (c) 2↓...Coal or foreign matter

Claims (1)

[Claims] 1. A plurality of spherical or roller-shaped pulverizing rollers and a race-like or ring-shaped rotary pulverizing ring are provided, and the pulverizing rollers and the pulverizing ring pressurize and pulverize coal; In a coal crushing mill having a function of supplying generated pulverized coal to a burner, at least three position detectors are installed to constantly measure changes in the distance between the crushing ring and the crushing roller at a set point and detect any abnormality. An abnormality detection device for a coal crushing mill, characterized in that it is installed at a location. 2. By comparing and calculating the signals input from the position detectors provided at a plurality of positions as set forth in claim 1 with the signal value in the normal state of the coal grinding mill, the abnormal state of the coal grinding mill is detected. An abnormality detection device for a coal crushing mill, characterized in that it is provided with means for early detection and warning or display. 3. In the coal pulverizing mill according to claim 1 or 2, the position at which a change in distance between the pulverizing ring and the pulverizing roller is measured at a set point between the pulverizing roller and the pulverizing roller is located at An abnormality detection device for a coal crushing mill, characterized in that the device is located on a pressure frame provided at the top of the machine and at a position corresponding to each crushing roller.