JPS62276318A - Mill outlet temperature control method - Google Patents

Abstract

PURPOSE:To enable a temperature at a mill outlet to be held at a given value, by a method wherein a flow rate of primary air to a mill is regulated according to a moisture content of coal fed to the mill. CONSTITUTION:An amount of coal stored in a coal feeder 1 is controlled through the working of a coal feed amount regulating device 10 by means of a mill master instruction 9 by feedbacking a weighing signal from a weighing machine 11, mounted to the coal feeder 1, to a subtractor 12. A coal feed instruction from the subtractor 12 produces a primary air flow rate instruction 14 by means of a function converter 13, and a flow rate signal from a flow meter 16, mounted to the inlet of a mill 2, is fedback to a subtractor 17 to feed primary air according to the instruction 14. A moisture content of coal previously fed to the mill 2 is measured, a change in temperature at the outlet of the mill due to the coal is read by means of a temperature detector 21. The temperature at the outlet of the mill is restored to a specified value, and an increase in a primary air flow rate required for maintenance of the temperature is measured, and a primary air flow rate set by the air flow rate instruction 14 is increased by means of an increase instruction device 19.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for controlling the mill outlet temperature of a vertical mill.

[Prior Art] In the case of a vertical pulverized coal mill, the amount of coal fed is adjusted by a mill master command, and the flow rate of primary air for conveying pulverized coal to the mill is controlled according to the amount of coal fed. It has become.

[Problems to be Solved by the Invention] However, in the conventional method described above, the primary air flow rate is only changed depending on the amount of coal fed, so for example, when coal with a high moisture content is fed, However, there was a problem in that the mill outlet temperature (mill internal temperature) decreased and the coal pulverization properties deteriorated, making stable operation impossible.

The present invention was made by focusing on the above-mentioned conventional problems.
When coal with high moisture content is supplied to the mill, the purpose is to maintain the mill outlet temperature by increasing the primary air flow rate and ensuring the amount of heat supplied.

[Means for solving the problems] The present invention attempts to solve the above technical problems, and
By adjusting the primary air flow rate to the vertical pulverized coal mill, which is adjusted according to the amount of coal supplied to the mill, according to the moisture content of the coal supplied to the mill, the mill outlet temperature can be maintained at a predetermined value. The present invention relates to a mill outlet temperature control method characterized by maintaining the temperature at a certain temperature.

[Function] Therefore, in the present invention, the mill outlet temperature can be adjusted by detecting the moisture content of the coal supplied to the mill and changing the primary air flow rate supplied to the mill according to the moisture content. It can be maintained within a predetermined specified temperature range.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

The drawing shows an example of the present invention, in which coal from a coal feeder 1 is supplied to a vertical pulverized coal mill 2, and the mill 2 is supplied with hot air 3 and cold air 4. Primary air 7 mixed and adjusted to a required temperature by a damper 5.6 is supplied via a primary air flow rate control damper 8.

The amount of coal fed into the coal feeder 1 is determined by a mill master command 9 via a coal feed amount adjustment device 10, and a measurement signal from a measuring device 11 provided in the coal feeder 1 is fed back to a subtracter 12. The system is controlled so that coal is fed as instructed.

Further, the coal feeding command from the subtractor 12 is converted into a primary air flow rate command 14 by a function converter 13 and is inputted to a flow rate adjustment device 15 that operates the flow rate control damper 8. The flow rate signal from the flowmeter 16 is fed back to the subtractor 17 and is then used as the primary air flow rate command 14.
The primary air supply is controlled to take place.

In the above configuration, an increase command device 19 is provided that changes (applies a bias) to the primary air flow rate command 14 from the function converter 13 via an adder 18 so as to increase the primary air flow rate.

Furthermore, the conveyance mixing ratio (A/C-A) of the primary air 7 and pulverized coal is
IR/C0AL), the flow rate adjustment device 15
It is equipped with a lower limit function (low limiter) to put a brake on it. In the figure, 20 indicates a pulverized coal pipe that supplies pulverized coal to a boiler burner, etc., and 21 indicates a mill outlet temperature detector.

The amount by which the primary air flow rate is increased by the increase command device 19 is determined by measuring the moisture content of coal supplied to the mill 2 in advance, and adjusting the mill outlet temperature after the moisture content of the coal is supplied to the mill 2. It is determined by reading the change in the temperature with the temperature detector 21, and measuring the increase in the primary air flow rate required to return the mill outlet temperature to the specified value and maintain that temperature. Furthermore, the amount of primary air 7 may be increased in accordance with the moisture percentage of the coal, or may be increased by a certain amount when the moisture content exceeds a certain value.

When the increase command from the increase command device 19 disappears, 1
The primary air flow rate is reduced until commanded by the secondary air flow command 14.

It should be noted that the present invention is not limited only to the above embodiments (
However, various changes may be made without departing from the spirit of the invention.

[Effects of the Invention] As described above, according to the mill outlet temperature control device of the present invention, the primary air flow rate that is being supplied according to the amount of coal fed can be adjusted according to the moisture content of the coal that is supplied to the mill. By changing this, when coal with high moisture content is supplied, the temperature inside the mill decreases and the pulverization of the coal decreases, which can be prevented.
It can produce excellent effects that enable stable operation of the mill.

[Brief explanation of the drawing]

The drawing is an explanatory diagram showing the configuration of a control circuit that implements the method of the present invention. 1 is a coal feeder, 2 is a vertical pulverized coal mill, 7 is primary air, 8 is a primary air flow rate control damper, 9 is a mill master command, lO
1 is a coal feeding amount adjustment device, 11 is a weighing machine, 12 is a subtracter, 13
is a function converter, 14 is a primary air flow rate command, 15 is a flow rate adjustment device, 16 is a flow meter, 17 is a subtracter, 18 is an adder,
19 is an increase command device, and 21 is a temperature detector.

Claims (1)

[Claims] 1) By adjusting the primary air flow rate to the vertical pulverized coal mill according to the amount of coal supplied to the mill, depending on the moisture content of the coal supplied to the mill, the mill outlet temperature can be adjusted. A mill outlet temperature control method characterized by maintaining the temperature at a predetermined temperature.