JPS6031544B2 - How to control the amount of pulverization in a pulverizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the amount of pulverization in the pulverization of agglomerates, and more particularly, the present invention relates to a method for controlling the amount of pulverization in the pulverization of agglomerates, and more specifically, in the operation of a pulverizer configured to immediately carry out pulverized powder or granules by airflow, the amount of pulverization can be controlled. The present invention relates to a method that can control over a wide range of conditions.

Coal resources are being reviewed in line with the deterioration of the oil situation, but reducing the consumption of oil as an energy resource has become a particularly important issue worldwide, and the ratio of coal fuel use is rapidly increasing. ing.

The usage of coal fuel can be roughly divided into methods in which it is burned as a lump, and methods in which it is crushed and burned, but the latter method is becoming the mainstream due to the tendency of high-quality coal to brown. When pulverizing coal and transporting it to the road for combustion,
Usually, crushing and unloading are carried out according to the concept shown in Fig. 1. That is, the crusher 1 is equipped with a crushing motor M, and a raw material input device 2 is disposed above the side wall of the crusher 1, into which raw coal 3 is input. On the other hand, an air jet nozzle is provided below the crusher 1 to pressurize the discharge gas (for example, nitrogen gas),
The pulverized coal that has been pulverized in the pulverizer 1 is discharged from above while being classified and is supplied to the user side along the direction of arrow A. However, the demand for pulverized coal on the user side does not remain constant, and sometimes the minimum demand is less than 1/3 of the maximum demand, so when operating the pulverized coal supply system as described above, it is necessary to It is necessary to be able to automatically control the supply amount according to the demand amount. Therefore, in conventional equipment, a pressure difference controller PdC is installed in the discharge gas blowing line.
In addition, a rotation speed controller SC of the driving side motor 5 in the raw material input device 2 is provided, and a pressure difference controller PdC is provided.
The system is configured to control the amount of raw material input based on the output signal. That is, in the above control, the amount of raw material retained in the crusher 1 is always controlled to be constant, and during steady operation, the differential pressure before and after the air jet nozzle is measured and set in advance. Stable operation of the pulverizer is achieved by controlling the raw material input device according to fluctuations from the established differential pressure. If you want to actively change the amount of pulverization, change the differential pressure setting above to match the amount of pulverization, and increase or decrease the input amount according to the difference between the set value and the measured value to reach the target amount of pulverization. It is to be ensured. However, in the conventional method described above, instead of adjusting the crushing motor of the crusher,
Since the amount of crushed material is controlled by using the amount of raw material retained in the crusher as a cushion and adjusting the amount of raw material input, the control range for the amount of crushed material is small, and the ratio between the maximum amount of crushed material and the minimum amount of crushed material is at best , 1.5 to 2 times the egg retention was not too strong. The present invention has been made in view of these circumstances, and its purpose is to provide a control method that can widen the control range of the amount of pulverization as much as possible.

However, in the present invention, when increasing or decreasing the amount of pulverization, instead of changing the set differential pressure of the injection nozzle, the amount of raw material input is actively increased or decreased, and the resulting difference between before and after the nozzle is Either by detecting the pressure change and changing the rotation speed of the crushing motor so as to return this differential pressure to the set differential pressure, or by first changing the rotation speed of the motor to change the differential pressure before and after the nozzle, Next, the gist is to change the amount of raw material carried in so as to return this differential pressure to a set differential pressure. That is,
Since the differential pressure setting before and after the injection nozzle is not changed, the optimal differential pressure can be maintained, and the control is performed by actively changing the raw material input amount or the crushing capacity, so the control range for the crushing amount is wide. It was expanded into the inside. Second
The figure is a graph showing the principle of the present invention in comparison with the conventional method shown in Fig. 1. The vertical axis shows the amount of grinding, the horizontal axis shows the rotational speed of the grinding motor, and the linear line shows the difference in pressure that has been set. It shows the relationship between the turning speed and the amount of grinding.

In other words, there is a proportional relationship between the rotation speed and the amount of pulverization, and considering the set differential pressure as a parameter, if the set differential pressure is large, (△P
, >△P2>△P3), it can be seen that even with the same crushing capacity, the amount of crushed coal is large, and the crushed pulverized coal is carried out one after another. By the way, in the conventional control method, for example, when the set differential pressure is △P2, the rotational speed of the crushing motor at that time is S, and the crushing amount is Q (state of point 1), and the crushing amount is Q' When attempting to increase the pressure to ΔP, the set differential pressure ΔP is determined so that the amount of pulverization shows Q' at the rotational speed S, and the set differential pressure before and after the nozzle is changed to ΔP (state at point B).

Therefore, since the operating differential pressure at that point is near △P2,
A difference of △P, - △P2 occurs between the set differential pressure △P, and the set differential pressure △P. Therefore, in the conventional method, the raw material input amount is increased until the actual grinding amount returns to Q' (in terms of control, until it becomes △P, = △P2).
That is, control is performed from point 1 to point B. Therefore, if the amount of pulverization is to be further increased, the set differential pressure ΔP must be further increased, resulting in a decrease in control accuracy. In contrast, in the present invention, the set differential pressure itself is fixed at a pressure preferable in terms of control accuracy, for example, △P2 (state of point 1), and ○}
Increase the amount of input to match the amount of pulverization without changing the rotation speed of the pulverizer motor (state at point m), detect the difference between the measured differential pressure and the set differential pressure △P2, and make sure that this difference is zero. Increase the rotation speed of the crushing motor until it reaches (state of point W), or '
2) Increase the rotation speed of the crushing motor without changing the raw material input amount (state of point V), and then adjust the measured differential pressure and set differential pressure△
Either the difference in P2 is detected and the raw material input amount is increased until this difference becomes zero (state at point W), or one of the methods is adopted.

If it is desired to reduce the amount of pulverization, the rotational speed of the pulverization motor may be controlled in the opposite direction to the above. In other words, while the conventional control method mainly focused on adjusting the amount of raw material immersion and did not combine the adjustment with the rotation speed of the crushing motor,
Since the crushing capacity itself is controlled by adjusting the rotational speed of the crushing motor, the amount of crushing can be controlled over a wide range.

Figures 3 and 4 are flow sheets for implementing the control method of the present invention, and Figure 3 is a flow sheet for implementing the control method of the present invention. Figure 4 shows the flow sheet for the second method (i.e.,
A method for changing the rotation speed of the crushing motor and controlling the amount of raw material input accordingly.

-It is a sheet. That is, in the flow sheet of FIG. 3, the pressure difference controller PdC and the rotation speed controller SC of the driving side motor in the raw material feeding device 2 are made independent, and the pressure difference controller Pd
The signal C is configured to be input to the rotational speed controller SC of the crushing motor M, and in the flow sheet of FIG. is set, and the signal from the pressure difference controller PdC is input to the rotation speed controller SC of the driving side motor in the raw material input device 2. Since the present invention is constructed as described above and directly incorporates the crushing capacity of the crusher as a control factor, it has been possible to greatly expand the control range of the crushing amount.

Moreover, it can be widely applied not only to the field of coal pulverization but also to all pulverization methods that are combined with a powder pneumatic conveyance method.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of the conventional method, FIG. 2 is a principle diagram showing a comparison between the method of the present invention and the conventional method, and FIGS. 3 and 4 are flow sheets of the method of the present invention. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. Control of the amount of pulverization in the operation of a pulverizer that is operated by a pulverizer motor and is configured to air-flow powder and granules using gas that is injected through an air-flow jet nozzle. This method detects the change in the differential pressure before and after the nozzle due to the change in the input amount, and controls the rotation speed of the motor so that the differential pressure matches the set differential pressure. Control method. 2. When controlling the amount of pulverization in the operation of a pulverizer that is operated by a pulverizing motor and is configured to air-flow the powder and granules by gas injected through an air-flow jet nozzle, the motor A method for controlling the amount of pulverization, characterized by detecting a change in differential pressure before and after a nozzle due to a change in rotational speed, and controlling the input amount so that the differential pressure matches a set differential pressure.