JPS6246125A - Coal supply method - Google Patents

Abstract

PURPOSE:To measure a coal quantity and supply it accurately over a range from the full load condition to a low load condition by adjusting the thickness of a coal layer on a conveyer belt with adjustment of baffle plates location in the vertical direction and also adjusting a belt speed to meet the required coal supply quantity with measurement of a coal weight. CONSTITUTION:A motor 6 moving up and down is driven to move baffle plates 2 vertically by a control device 8 according to an operating condition of a mill and a layer thickness of coal 3 on a belt 4 is determined. The weight of coal in the belt 4 is measured by a load meter 5 and its measured result is input to the control device 8. The control device 8 calculates a travel speed of the belt from said measured result and the required coal supply quantity and a travel quantity of the belt 4 is allowed to coincide with the calculated result by control of a motor 7. For a substantial change, the baffle plates 4 are moved up and down to accommodate an expected change in supply quantity and the thickness of the coal layer is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a coal supply method for continuously feeding coal to a mill while being metered.

[Prior Art] In a device that uses pulverized coal as fuel, such as a pulverized coal-fired boiler, coal is pulverized in a mill and sent as fine powder to a burner. Therefore, in order to stably feed the required amount of pulverized coal to the burner, it is necessary to measure the amount of coal fed to the mill.

As conventional coal supply methods, those shown in Figs. 2 and 3 are available.

First, in FIG. 2, coal is supplied by a belt conveyor 1, and a baffle plate 2 is provided at a required position above the belt conveyor 1, and a required gap is maintained between the lower end of the baffle plate 2 and the belt conveyor 1. When the coal 3 is fed by the belt conveyor 1, the thickness of the coal layer on the belt 4 is kept constant, and the moving speed of the belt is adjusted by the controller 1 to the roll of the motor 7. The purpose is to measure and supply coal using a constant coal input wind controlled by the baffle plate 2 and the baffle plate 2.

In addition, in the one shown in FIG. 3, a load cell 5 such as a load cell is provided so as to come into contact with the lower surface of the belt 4, and the coal 3 loaded on the belt conveyor 1 is weighed, and based on this weighing result and the speed of the bell 1. This is an attempt to measure the amount of supply.

[Problem to be solved by the invention] In the operating state of the mill up to now, under the full load state, when a square tube is
It is operating at approximately 0% load.

However, in the future, with the use of low-load burners, etc., it is expected that the operating rate will further decline, for example to about 10% for a total of 9 loads.

In both of the above two methods, the coal supply amount is controlled by controlling the motor rotation speed, and controlling the motor rotation speed requires that the motor rotates at a predetermined speed or higher. If it is about 10% of the load, it becomes impossible to measure in reality.

In view of these circumstances, the present invention attempts to accurately meter and supply coal from a full load state to a low load state.

[Problems to be Solved by the Invention] The present invention adjusts the vertical position of the baffle plate in accordance with the required coal supply amount to adjust the thickness of the coal on the conveyor belt. It measures the weight of coal and adjusts the belt speed to match the amount supplied.

[Function 1: Because the thickness of the coal on the belt is adjusted by the obstruction to the maximum coal supply, the motor speed control only needs to be within a small range, and the speed can always be adjusted within the optimum speed range, with good control accuracy. .

[Implementation Example 1] The present invention will be described in detail below with reference to the drawings.

First, to explain the outline of the device, a baffle plate 2 is supported so that it can be raised and lowered, and its position can be changed in stages by a lifting motor 6, and a load meter 5 is brought into contact with the lower surface of the belt 4. The width of the coal 3 loaded on the belt 4 is measured.

The method will now be described along with the operation of the device.

The lifting motor 6 is controlled by the control device 7 according to the operating state of the mill.
is driven to raise and lower the baffle plate 2 to determine the thickness of the layer of coal 3 on the belt 4. The weight of the coal 3 loaded on the belt 4 is measured h1 by the load cell 5, and the measurement result is sent to the control device 7.
Enter.

The control device 8 calculates the moving speed of the belt 4 from this measurement result and the required coal supply amount, and controls the motor 7 so that the moving amount of the belt 4 becomes equal to the calculated result. Small changes in the supply amount are controlled by the rotation speed of the motor 7, but for large changes, the obstruction 2 is raised and lowered to compensate for the change in the supply amount. Adjust the thickness.

After adjusting the layer thickness, the motor 7 is controlled in the same manner as described above.

In this method, the thickness of the coal layer is adjusted according to the operating rate of the mill, and then the speed of the motor 7 is controlled. It is possible to provide sufficiently accurate measurements even when the number of units is reduced.

Incidentally, in the above embodiment, the height of the baffle plate may be set at an arbitrary position that is changed stepwise.

[Advantageous Effects of the Invention 1] As described above, according to the present invention, it is possible to measure with high precision from a full load state to a low load state, and to provide stable supply.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for carrying out the present invention, FIG.
FIG. 3 is an explanatory diagram of each conventional example. 1 is a conveyor belt, 2 is an obstacle, 3 is coal, 4 is a belt, 5 is a load cell, 6 is a lifting motor, 7 is a motor, and 8 is a control device.

Claims (1)

[Claims] 1) The thickness of the coal on the conveyor belt is adjusted by adjusting the vertical position of the baffle plate in accordance with the required coal supply amount, and the belt is adjusted to match the supply amount by measuring the weight of coal on the belt. A coal feeding method characterized by adjusting the speed.