JPH01199658A - Structure for regulating throat area - Google Patents

Abstract

PURPOSE:To easily regulate the throat area of a grinding machine and to enable operation even when powder of coal, etc., is bitten by performing regulation of the throat area of the grinding machine with rotation of a nearly columnar valve body having an air passage. CONSTITUTION:A nearly columnar valve body 35 is turnably provided in the air passage 38 of the throat parts 33, 34 passing air therethrough. A through-hole 37 coaxial to the air passage 38 is bored to the valve body 35 and also both end edge parts of the valve body 35 are formed into the curved convex faces and the inner face of the air passage 38 abutted on the valve body 35 is formed into a curved concave face coincident with the above-mentioned curved convex face respectively. Further, an operation body 36 for turning the valve body 35 is fixed to this valve body 35. As a result, powder of coal, etc., is prevented from being bitten into the throat part and thereby malactuation of the throat part is not caused.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a throat area adjustment structure, and in particular, to a throat area adjustment structure that prevents crushed material from being caught in the throat portion of a crusher, thereby preventing malfunction of the throat portion. Regarding throat area adjustment structure.

[Conventional technology]

In the electric power and cement industries, crushers play an extremely useful role in stably supplying pulverized coal, which serves as fuel, to boilers.

FIG. 5 shows a typical flow of a coal-fired boiler using such a crusher. As shown in the figure, in a coal-fired boiler, the combustion air A is.

After passing through the forced draft fan 1, it is divided into water air B and secondary air C. Furthermore, after passing through the water-air forced draft fan 4, the water-air B is divided into cold air, which is sent directly to the crusher 5, and hot air, which is superheated through the air preheater 3. The cold air and the hot air are mixed before the pulverizer, and the temperature at the inlet of the pulverizer 5 is controlled to a predetermined temperature. Further, the secondary air C is sent to the boiler 8 after passing through the steam air preheater 2 and the air preheater 3 and being superheated.

On the other hand, coal coal is supplied into the crusher 5 from the coal bunker 6 via the coal feeder 7, and is crushed by the crusher ja5. The pulverized coal is transferred to the burner 26 of the boiler 8 by the primary air B.
and is combusted by secondary air C in the boiler 8.

In the figure, 9 is a dust collector, 10 is a denitrification device, 11 is an induced draft fan, 12 is a desulfurization device, and 13 is a chimney.

Further, the crusher 5 is constructed as shown in FIG. As shown in the figure, coal coal having an average diameter of about 2 to 70 mm is supplied to the crusher 5 through a coal feed pipe 14, and
6. Fall upwards. The crushing table 16 is connected to an electric motor 17 via a speed reducer 32, and rotates at 20 to 40 rpm. Further, a crushing load is applied to the roller tire 18 on the crushing shaft 19 attached to the crushing table 16 from an external pressure device 20, and the roller tire 18 rotates as the crushing shaft 19 rotates. . Then, the coal that has fallen onto the crushing table 16 is conveyed by centrifugal force between the crushing shaft 19 and the rotating roller tire 18, and as it passes between them, it is crushed and sent to the upper part of the throat 21.

On the other hand, air B is heated to around 150-300℃,
The coal is uniformly supplied to the throat 21 through the chamber 22, and the pulverized coal is conveyed in the upper part thereof while being dried. Relatively fine particles of the pulverized coal are carried by the secondary air B and sent to the classifier 24 via the vane 23. Coarse particles are separated from the air flow as the air flow rate decreases and are returned to the grinding table 16 (this is referred to as -order classification). Inside the classifier 24, a centrifugal force acts on the coal particles due to the swirling flow, and relatively coarse particles fall through the classifier 24 and are returned to the crushing table 6 by the flapper 25.
This is called secondary classification). And only fine particles coal feed pipe 15
is supplied to the burner 26 through.

Conventionally, about 70% of the coal supplied to the burner 2-6 has a particle size of 200 mesh (74 μm or less). In addition, the pulverizability of the coal used (evaluated by HGI) and the fuel ratio (ratio of fixed carbon to volatile content in coal) that affect combustibility are approximately 1, both of which are particularly problematic for boiler combustion. There were few.

On the other hand, in recent years, it has been found that increasing coal particle size is extremely effective in order to diversify coal types, strengthen environmental regulations, and ensure high efficiency combustion.

However, if an attempt is made to improve the particle size, the amount of coal circulating in the crusher 5 (-1 secondary classification increases the amount of returned coal E) increases. For this reason, the coal seam above the throw 1-21 becomes J', and the amount of coal that passes through the throat 21 and falls to the air B increases. This fallen coal is stored in a pie-rai box 28 by a blow 27 attached to the crushing table 16, and is taken out to the outside at regular intervals. However, when the amount of falling coal increases, not only does the utilization rate (combustion efficiency) of 1 coal decrease, but also the pyrite box 2
8 may become full, sometimes causing the crusher 5 to trip, making it impossible to stably supply coal to the burner 26, which may seriously affect the power plant.

Conventionally, the increase in falling coal particles was dealt with by increasing the amount of secondary air B and increasing the flow velocity in the throat 21 section, but increasing the flow velocity decreased the primary classification performance and caused the coal to deteriorate. The fine particle size deteriorates, and - Air forced draft fan 4
There were problems such as an increase in power.

Therefore, as shown in FIG.
9 and rotate the adjustment bolt 29, the throat area can be adjusted while moving the throw 1-play 1 to 30 in the width direction of the throat. I was trying to lower the power.

[Problem to be solved by the invention]

However, in the above conventional technology, when adjusting the throat area, the throat plate 1- is moved in the width direction of the throat plate 1-, so powder such as coal gets caught between the throat plate and the throat plate, resulting in malfunction. This situation often occurred. In addition, a large force is required to move Slow 1 to Play 1 in the width direction of the throat, and when the crusher is automated, there is a problem in that a large actuator must be installed.

An object of the present invention is to provide a throw area adjustment structure that prevents powder such as coal from being caught in the throat area and prevents malfunction of the throat section.

[Means to solve the problem]

In order to achieve the above object, the throat area adjustment structure of the present invention includes a substantially cylindrical valve body rotatably provided in an air passage of a throat portion through which air passes, and a substantially cylindrical valve body that is coaxial with the air passage. A through hole is formed, both end edges of the valve body are formed into convex curved surfaces, and the inward direction of the air passage that contacts the valve body is formed into a concave curved surface that matches the convex curved surface, and the valve body is An operating body for movement is fixed to the valve body.

[Effect]

According to the above configuration, the valve body rotates within the air passage as the rotating body rotates, and the direction of the through hole formed in the valve body changes with respect to the direction of the air passage. Therefore, the area of the air passage can be freely changed at the open end of the through hole, and the flow rate of air passing through this position can be adjusted. In this case, even if pulverized material gets caught in the gap between the throat part and the valve body, it is possible to easily crush the pulverized material by moving the valve body at the same time. And since the inner surface of the air flow path facing the valve body is formed into a convex curved surface and a concave curved surface, respectively, air flows into the gap, and the crushed crushed material is discharged from the gap to the outside by the air flow. Can be done.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. Note that the same parts as in the prior art are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

In the throat area adjustment structure according to the present invention, as shown in FIG.
A substantially cylindrical valve body 35 is disposed between the two throats 33 and 34. Both end edges of the valve body 35 are formed into convex curved surfaces, and upper and lower throats 33;
The inner surface of the valve body 4 is also formed into a concave curved surface so as to match both end edges of the valve body 35. A shaft 36 is fixed to one surface of the valve body 35 as an operating body, and one end of this shaft 36 protrudes outside the housing 31 of the crusher. If the shaft 36 is rotated from the outside, the valve body 35 can be easily rotated.

Further, a through hole 37 is formed in the valve body 35 coaxially with the air flow path 38 of the upper and lower throats 33 and 34.
Primary air B is designed to flow within the chamber 7. and,
When the valve body 35 rotates, as shown in FIG. 2, the area of the through hole 37 of the valve body 35 relative to the air passage 38, that is, the throat area can be changed.

As mentioned above, the valve body 35 operates like a ball valve between the upper and lower throws 1-33, 34, and its sliding direction is only in the circumferential direction of the valve body 35. In fact, in an atmosphere where there is powder, such as in a crusher, it is better to have the sliding direction in the circumferential direction to prevent the powder from getting caught, and even if it does get caught, the powder can be removed by rotation. It can be easily crushed and expelled. Therefore, the throat area can be easily adjusted and the reliability of the crusher is improved.

Generally, by reducing the throat area, the amount of falling coal can be reduced. An example of this is shown in FIG. 4. As is clear from the figure, it is possible to reduce the amount of falling coal by increasing the primary air flow velocity at the throat. On the other hand, if there are few fallen coal objects, the operation may be performed by lowering the secondary air flow velocity.

Another embodiment of the invention is shown in FIG. In this embodiment, an electric motor 39 is added to the above-described embodiment, and the electric motor 39 is connected to the shaft 36 via a worm gear 40 and a gear 41. Note that 42 is a bearing that rotatably supports the shaft 36.

According to this embodiment, the electric motor 39 can be driven by an external signal, and the valve body 35 can be rotated automatically. For example, if the amount of falling coal particles is measured, and an abnormality occurs, an external signal will be used to reduce the throat area and increase the air flow velocity to reduce the amount of falling coal particles.If the situation returns to normal, the throat area will be increased. By lowering the primary air flow velocity, this operation is automatically performed to stabilize the operation of the crusher. By automating the adjustment of the throat area in this way, it is possible to significantly eliminate the time loss that would otherwise have been spent on the adjustment.

〔Effect of the invention〕

As described above, according to the present invention, the throat area is adjusted by rotation, which facilitates the adjustment and allows operation even when powder is caught. Furthermore, since the falling objects from the throat are adjusted without increasing or decreasing the primary air, a constant mixture of coal and air can be provided to the burner and combustion can be stabilized. Furthermore, it is possible to reduce falling coal particles, contributing to stable operation of the crusher.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a throat area adjustment structure according to the present invention, FIG. 2 is a plan view of the main part of FIG. 1, and FIG. 3 is a sectional view corresponding to FIG. 1 showing another embodiment. Figure 4 is a diagram showing the relationship between the throat-firebox air velocity ratio and the ratio of coal falling from the throat. Figure 5 is a system diagram of a coal-fired boiler. Figure 6 is a structural diagram of a crusher. FIG. 7 is a sectional view showing a conventional throat area adjustment structure. 33...Upward throw 1~. 34...lower throat. 35... Valve body, :36... Shirt 1~. 37...
Through hole. 38...Air passage.

Claims (1)

[Claims] 1. A substantially cylindrical valve body is rotatably provided in the air passage of the throat portion through which air passes, a through hole coaxial with the air passage is bored in the valve body, and both end edges of the valve body are provided. is formed into a convex curved surface, the inner surface of the air passage that contacts the valve body is formed into a concave curved surface that matches the convex curved surface, and an operating body for moving the valve body is fixed to the valve body. Adjustment structure.