JPS60259820A - Operation method of mill - Google Patents

Abstract

PURPOSE:To warn of a malfunction of a mill for preventive maintenace by comparing the anticipated value and measured value of characteristic of the mill under operation so that when the deviation is above a predetermined value, the mill may be stopped, and the load may be distributed by starting a reserve or standby mill, or by switching to other mill under operation. CONSTITUTION:The amount of wear of a roll and a segment is predicted based on the anticipated curve of the maximum amount of wear of the roll and segment versus operation hours, which is prepared by analyzing the amount of wear of mills in service, and the mill operating hours. Then, an anticipated power consumption by a mill is determined based on the feed amount of coal, kind of coal used, amount of wear of roll and segment and correction of opening of deflector vane. A malfunction of a mill is detected by the deviation between the anticipated power consumption of the mill and the real value. Regarding the mill vibration, the presence or lack of a malfunction is detected by comparing the data of a new roll and the measured value. In this manner, the stoppage of a mill, the starting of a reserve or standby mill, or the load distribution to other mill under operation is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of operating a mill (pulverizer) for supplying pulverized coal to a coal-fired boiler or the like.

[Conventional technology]

Until now, no comprehensive status display system for mills has been proposed, only recorders.

The amount of coal fed, mill vibration, etc. were recorded or indicated on indicators. Therefore, prediction of mill abnormalities and preventive maintenance are not sufficiently performed.

[Problem that the invention seeks to solve]

For example, in a coal-fired boiler, the unexpected occurrence of mill trouble causes a number of problems, such as consumption of auxiliary oil and interference with stable operation. Because the condition of the trench mill is not understood, rational management and maintenance of the mill is not being carried out.

[Failure to solve the problem]

Amount of coal fed into the mill during operation 9 Coal properties (HGI, moisture.

Ash content), roll segment wear amount, and deflector vane opening degree to the corresponding mill characteristics (roll rotation speed, bowl differential pressure, mill power.

When the deviation is greater than a certain value by comparing the predicted value with the actual measured value (mill vibration).

Stop the mill and start a standby or standby mill, or
A method of operating a mill characterized by distributing load to other operating mills.

〔Example〕

Hereinafter, a case will be described in which an embodiment of the present invention is applied to a method of operating a coal-fired boiler mill.

Understanding and managing the status of the mill system, which is most closely related to a coal-fired boiler, is considered to be of great benefit to thermal power plants and the like that have one coal-fired boiler. In other words, it is especially important for the economic management of thermal power plants to accurately understand the effects of characteristics and operating conditions on various types of coal.

In accordance with the present invention, the drawings show the type of coal used in each mill, the amount of coal fed, the wear amount of the roll segments, the opening degree of the deflector vane, and the mill characteristics (roll rotation speed).

An example is shown in which a computer predicts predicted values and actual measured values of bowl differential pressure, mill power, mill vibration, etc., and displays them on a CRT screen. The ○○○ mark in the diagram is the actual measured value (current operating status), XXX
The marks are predicted values.

Each predicted value can be determined using the following method. (1) Amount of wear on rolls and segments Based on a long-term follow-up survey of the amount of wear on mills that have already been installed, the maximum amount of wear and operating time for rolls and segments can be predicted. Create a curve.

The wear amount of the roll segment is predicted from the same curve and the mill operating time. After creating Hiko-Oko's predicted curve, it was compared with actual wear data from other mills and was confirmed to match very well.

(2) Roll rotation speed R = K, -2W R flow rotation speed (rpm) W: Coal feed amount (T/H) K,, K2: Coefficient (3) Bowl differential pressure * △PB = (ΔPB + f, ) x f2x f3△PB
: Bowl differential pressure △PB”: Reference value calculated from coal feed amount fl: Coal type correction f2; Wear correction f3: Deflector vane opening correction (4) Mill power* △PIN ==Δpm X f4 X f5 X f6
△Pm: Mill power * △Pm: Standard value based on coal feed amount f4: Wear correction f5; Deflector vane opening correction f6: Coal type correction (5) Mill vibration Measure the vibration value of the new roll with respect to the coal feed amount, Store this in your computer.

In accordance with (1) to (5) above, regarding the roll rotation speed among the mill characteristics, calculate the expected rotation speed using the formula (2) from the coal feeding amount, and then calculate the actual rotation speed (actual value). A comparison will be displayed on the CRT screen. This determines whether the roll rotation speed is normal or abnormal.

Next, regarding the bowl differential pressure, we will calculate (3
) is used to calculate the expected bowl differential pressure and compare it with the actual value. Detection of mill capacity limit.

This is usually done by monitoring the bowl differential pressure.

The bowl differential pressure is not taken as an absolute value, but a mill abnormality is detected by a large deviation from the expected state (predicted bowl differential pressure). What is the concept of predicting the bowl differential pressure in equation (3)?

It adds corrections for operating conditions and coal type to the base bowl differential pressure. Especially the coal type correction.

Since the prediction is made from coal property values such as HGI (grindability), moisture, and ash content, it has the versatility of being able to predict any coal that may be used in the future, and the predicted value is more accurate. Furthermore, conventionally, the bowl differential pressure alarm has been set as a single value, but by using the highly accurate predicted value, it becomes possible to set it in accordance with the operating conditions.

Next, regarding mill power, the amount of coal fed and the type of coal used.

(Roll safety) Wear t Calculate the expected mill power from the deflector vane opening correction. An abnormality in the mill can be detected based on the difference between the predicted mill power and the actual value. The mill power can also be set according to the operating conditions.

Finally, regarding mill vibration, the presence or absence of abnormal vibration can be detected by comparing the data of the new roll mentioned above with the actual measurement value.

The predicted values of the mill characteristics obtained using the method described above are compared with the actual values, and when the deviation exceeds a certain value, it is determined that the mill is abnormal and the mill is stopped.

Start-up of standby or standby mills or load distribution to other operating mills.

〔Effect of the invention〕

It makes it possible to predict mill abnormalities and carry out preventive maintenance, which greatly contributes to the stable operation of boilers, etc. Also, by understanding the condition of the mill, it becomes possible to set up a reasonable maintenance schedule.

Furthermore, it is possible to reduce the consumption of auxiliary fuel oil due to unforeseen problems with the mill.

[Brief explanation of the drawing]

The drawing is an explanatory diagram showing an example of display on a CR, T screen according to an embodiment of the present invention. 9 Continued from page 1 0 Inventor Shino 1) Katsuhiko Akunoura Town, Nagasaki City

Claims (1)

[Claims] The amount of coal fed into the mill during operation, the coal properties (HGI, moisture, ash content), the amount of wear of the roll segments, and the opening degree of the deflector vanes, and the corresponding mill characteristics (roll rotation speed, bowl difference). Calculate the predicted value of pressure, mill power, mill vibration) and compare the predicted value with the actual measured value, and when the deviation is greater than a certain value. A method for operating a mill, which comprises stopping the mill and starting a standby or standby mill or distributing load to other operating mills.