JPH01139158A - Operation of fine coal machine - Google Patents

Abstract

PURPOSE: To obviate excessive pulverization and to save the driving power of a machine for which deflector vanes are adopted as a pulverization granule size adjuster by increasing vane opening degree with a decrease in the supply rate of materials to be pulverized. CONSTITUTION: The coal feed rate and the opening degree 1 of the deflector vanes 5 at the time of operating a coal mill have the relation that the required driving power is successively decreased while the required granule size of fine powder is maintained by gradually increasing the deflector vane opening degree as the mill load is lowered. Then, if the opening degree of the deflector vanes 5 is increased with a decrease in the supply rate of the materials to be pulverized, since the amt. of the power returning as coarse powder to rollers and a bowl decreases rapidly the pulverization time is shortened. In addition, the driving power is saved and the wear of the rollers is lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of operating a coal pulverizer that employs a deflector bay as a fine particle size regulator.

[Conventional technology]

In recent coal-fired boilers, coal is pulverized into fine particles called pulverized coal (70 to 80% of the 200 liters of coal) and then combusted (pulverized coal combustion). In such pulverized coal combustion equipment, the device that turns coal into pulverized coal is called a pulverizer (hereinafter referred to as pulverizer).
It plays an important role in pulverized coal-fired boilers.

Figure 3 shows such a mill. Coal is fed into the mill from a coal feeder and is pulverized between rollers 3 and bowls 4 inside the mill, and is mixed with pulverized coal and coarse pulverized coal. Becomes a body. Here, pulverized coal refers to pulverized coal that satisfies the required particle size, and coarse pulverized coal refers to pulverized coal that does not satisfy the required particle size. This mixture is
The hot air supplied from the bottom of the bowl 4 is carried to the separator at the top of the mill. As shown in Fig. 4, the deflector vanes 5 of the separator change the angle of the pulverized coal flowing into the separator depending on the opening degree 2, giving a swirling force to the mixture of pulverized coal and coarse pulverized coal, and the centrifugal force accompanying the swirling causes the pulverized coal to become fine. Separate charcoal and coarse coal. The separated pulverized coal is further carried by air to the burner section of the boiler. The coarse pulverized coal passes through the lower part of the inner cylinder of the separator and falls onto the bowl 4 again, where it is re-pulverized by the bowl 4 and the rolls 3.

In this way, coarse powder with a particle size that does not satisfy the specified value (indicated by the 200 mesh passing rate of pulverized coal, which value is determined by the opening degree of the deflector vane 5) is processed by rollers and bowls until it satisfies the specified value. It circulates between the separator and the separator.

In the conventional mill operating method, the opening degree of the deflector vane 5 is set to a specified value of 200 when the mill load (coal feeding amount) is 100%.
The mesh passage rate was set to be 70 to 80%, and the set value was kept constant regardless of the mill load, that is, the amount of coal fed, as shown in FIG.

[Problem that the invention seeks to solve]

The conventional mill operating method described above has the following problems. In other words, with a deflector vane set at 100% load of the mill, when the mill load decreases, the amount of crushing per unit area of the roller decreases, so the crushing capacity of the mill increases, and even with the same vane opening, the fine particle size becomes finer and the coal becomes smaller. Excessive crushing (more than necessary for pulverized coal combustion). As a result, power was wasted. Inevitably, the rollers were also severely worn.

[Means for solving problems]

The present invention, as a solution to the above-mentioned problems, uses a roller and a bowl to pulverize a material to be pulverized, and a separator that separates the powder into fine powder and coarse powder depending on the opening degree of a deflector vane. A method for operating a pulverizer, characterized in that the opening degree of the deflector vanes is increased as the supply amount of the material to be pulverized is reduced, in the operation of a pulverizer that obtains fine powder by repeatedly returning it to a bowl and pulverizing it. This is what we are trying to provide.

[Effect]

Since the present invention is configured as described above, it has the following effects. In other words, as the supply amount (mill load) of the material to be crushed decreases, the opening degree of the deflector vanes of the separator is increased, so that the powder, which was previously more pulverized than necessary, now has an appropriate particle size and is passed as fine powder. As a result, the amount that returns to the roller and bowl as coarse powder rapidly decreases. Accordingly, the grinding time is also shortened.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a diagram conceptually showing the relationship between the amount of coal fed and the opening degree of the deflector vanes when operating the pulverizer according to the method of this embodiment. The degree of opening of the deflector vanes is increased proportionally as the amount decreases.

FIG. 2 is a diagram showing the power reduction effect achieved by the method of this embodiment using the deflector vane opening degree as a parameter in four cases ① to ②, where the mill load on the horizontal axis corresponds to the amount of coal fed.

In other words, the lower stage requires a mesh passing rate of 200. In order to maintain A, which is slightly higher than the minimum value of 70% for the fine particle size, when the mill load is 100%, the opening degree of the deflector vane needs to be ■. , indicates that ■ is sufficient near the mill load blade %. Similarly, it is shown below that ■ is sufficient in the vicinity of % between mill loads. That is, their intersection is A
, B, C, and D, moving to the left while maintaining the same 200 mesh passing rate. Note that here, the deflector vane opening degree is in the following relationship. The upper part of FIG. 2 shows the same 200 mesh passing rate as above, that is,
This shows the mill power required to maintain C and D at the deflector vane openings in four cases from ■ to ■.
It clearly shows that as the distance increases, the power needs to be smaller.

In other words, if the deflector vane opening is increased appropriately as the mill load is lowered, the required particle size of the fine powder will be maintained.
, which shows that the required power is gradually reduced, indicating that the method of this example saves power compared to the conventional method. By the way, in the case of the conventional method, the mill load is 10
Since the deflector vane opening degree ■ is set to maintain the fine powder particle size at point A at 0%, even if the mill load decreases, the power decreases along the line A-E in the upper row of Figure 2. Therefore, clearly more power is consumed than in the method of this embodiment.

As mentioned above, it has been explained that power can be saved by the example, but in addition, by increasing the opening degree of the deflector vane, the amount of coarse powder that returns to the rolls and/or (Ultra) is reduced. This also has the advantage that the circulating amount of powder is reduced, the grinding time is also shortened, and the amount of wear on the rollers is correspondingly reduced.

〔Effect of the invention〕

Since the present invention is configured as described above, it has the following effects.

(1) The power of the coal pulverizer is saved.

(2) Roll wear is reduced by avoiding excessive crushing.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the amount of coal fed to the pulverizer and the opening degree of the deflector vane according to the method of one embodiment of the present invention, and Fig. 2 is a diagram showing the power reduction effect according to the method of the above embodiment. , Fig. 3 is a vertical cross-sectional view of the pulverized coal mill (mill), Fig. 4 is a view taken along the IV-ff arrow in Fig. 3, and Fig. 5 is the relationship between the amount of coal fed and the opening degree of the deflector vane according to the conventional method. FIG. 3...Low, F, 4...Bawl, 5...Deflector vane. Agent Patent Attorney Akatsuki Sakama 2 people Im Funako - 2 years old It refers to the 11th and 11th press of Kudahan and the Nikan no Okaro method.

Claims (1)

[Claims] The material to be crushed is crushed by the rollers and bowl, and the powder is separated into fine powder and coarse powder by the opening degree of the deflector vane.The separator separates the powder, and the coarse powder is returned to the rollers and bowl, and the process is repeated to produce fine powder. A method for operating a pulverized coal machine, comprising increasing the opening degree of the deflector vanes as the amount of material to be pulverized is reduced.