JPS6154460B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for crushing and classifying materials to be crushed such as coal, and in particular, it is capable of consistently performing good crushing and classification regardless of the properties or quantity of the materials to be crushed. Our goal is to provide equipment that can.

Due to recent changes in the fuel situation, the value of coal as a fuel has been reconsidered, and coal is being co-fired with heavy oil in large boilers for business use, including large boilers for thermal power plants.
Alternatively, a considerable number of coal-fired boilers are used. In this case, from the viewpoint of improving the efficiency and controllability of coal combustion, a method is often adopted in which the coal is pulverized to a predetermined particle size and then airflow is transported to the burner section. Here, the volatile content of coal is first burned,
Thereafter, the fixed carbon in the coal undergoes a process of combustion, so the smaller the diameter of the coal particles, the shorter the combustion time per particle, making it easier to control the combustion of the coal as a whole. Furthermore, the reduction in particle size naturally increases the surface area of coal and increases its combustibility.
In other words, from the standpoint of combustion control and combustion efficiency, pulverized coal should have as high a content of pulverized coal as possible (e.g., 200 mesh passing rate of over 70%), and coarse coal with a larger particle size than pulverized coal should be used. It is necessary to reduce the content of granulated coal. However, the larger capacity of the coal crushing equipment cannot keep up with the increase in the capacity of the boiler, and the load on each crushing equipment tends to increase.
The reality is that the classification rate of pulverized coal is decreasing. In other words, the flow rate of air supplied to the classifier in the crushing device is increased to cope with the increase in load, so coarse coal that would otherwise fall into the crushing section due to its own weight before reaching the classifier also flows into the classifier. In many cases, the amount of pulverized coal flowing into the classifier increases significantly, resulting in a decrease in classification efficiency. Therefore, in order to maintain a high classification efficiency despite the increase in the amount of pulverization, it is necessary to increase the efficiency of primary classification, which is the classification of pulverized coal before it reaches the classifier.

FIG. 1 shows the structure and operation of a ball mill for crushing coal.

In the figure, the ball mill includes a coal feeding pipe 20,
Upper ring 14, lower ring 11, coal crushing section 30 including balls 12, power transmission section 90, classifier 5
0, a pulverized coal outlet pipe 60, a foreign matter discharge port 70, a primary air supply pipe 80, etc. Coal is supplied from the upper part of the coal feed pipe 20 located at the center of the mill housing 10 to the center of the coal crushing section 30 as shown by arrow c. The coal crushing section 30 has a stationary rotating lower ring 11 connected to a power transmission section 90.
A plurality of balls 12 that revolve and rotate on their own axis are placed on top of the fixed upper ring 1 that is pressurized with a spring or a nitrogen (N ₂ ) gas compression cylinder 13.
It is constructed by installing 4. The supplied coal is crushed by the lower ring 11 and balls 12 in the crusher 30, and is discharged to the outside of the crusher 30 by the rotation of the lower ring 11.

On the other hand, primary air A for combustion is supplied from the primary air supply pipe 80.
is supplied to the throat portion 40, the pulverized coal is blown up above the mill housing 10, and the guide vanes 52 apply swirling force to the air flow containing the pulverized coal.

In conventional equipment, this throat part is fixed, and the amount of air that passes through the slits formed in the slit plate and the direction of air injection cannot be changed, so it is necessary to perform appropriate primary classification according to the amount of crushed coal and its properties. This has been a cause of a decrease in the classification efficiency of the entire apparatus.

An object of the present invention is to provide a crushing and classifying apparatus which eliminates the above-mentioned problems and can always perform good crushing and classification regardless of the amount, properties, etc. of the materials to be crushed.

In short, this invention adjusts the flow rate or jet direction of air passing through the throat section by making the attachment angle of at least one of the throat plate constituting the throat section and the slit plate forming the slits variable. It is designed to increase efficiency.

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

In FIG. 2, reference numeral 100 denotes a slit plate, 1
01 is a throat plate, the slit plate 100 is attached to a wall surface forming a part of the mill housing 10 by a hinge 103, and the throat plate 101 is pivoted with respect to this slit plate 100 by another hinge 102 It is attached freely. 105 is a slit provided in the slit plate 100.

106 is a rod that adjusts the angle at which the slit plate 100 is attached to the mill housing 10;
One end of this rod 106 is attached to the back surface of the slit plate 100 with a hinge 107, and the other end is attached to a cylinder 106 operated by hydraulic pressure or the like.
It is connected to 9. 110 is a ball bearing that supports this rod 106, and 111 is a turnbuckle that adjusts the length of the rod 106.

On the other hand, the hinge 112 is also connected to the throat plate 101.
Another rod 113 is connected to the cylinder 114, and the other end of this rod 113 is connected to a cylinder 114. 115 is a ball bearing that supports this rod 113, and 116 is a turnbuckle that adjusts the length of the rod.

With the above configuration, the mounting angle of the slit plate 100 can be adjusted by using the rod 106 on the cylinder 10.
9, and the installation angle of the throat plate 101 can be adjusted via the rod 113 on the cylinder 1.
14 respectively.

That is, the device for rotationally displacing the slit plate 100 includes a rod 106, a turnbuckle 111, a ball bearing 110, and a cylinder 109. On the other hand, the device for adjusting the attachment angle of the throat plate 101 with respect to the slit plate 100 includes a rod 113, a turn buffle 116, a ball bearing 115, and a cylinder 1.
Consists of 14.

Slit plate 1 using the device according to this invention
00, the third diagram showing the flow rate and flow direction of the primary air velocity that changes the particle size distribution of pulverized coal when the installation angle of the throat plate 101 is changed.
This is schematically shown in figures A to 3C. For ease of explanation, FIGS. 3A and 3B show only the slit plate without the throat plate attached. Assume now that the mounting angle of the slit plate 100 with respect to the wall surface of the mill housing 10 is decreased from α to β while keeping the primary air amount constant. As a result, the flow path width of the throat section 120 becomes wider from _W1 to _W2 , and the primary air flow velocity at the throat increases from a to _a1 , and the primary air flow velocity passing through the slit 105 increases from b to _b1.
As shown in the figure, the combined flow direction c has an angle smaller than c with respect to c ₁ and the horizontal. Moreover, the flow velocity is also small. This means that particles with a large particle size are not carried to the guide vane 50, and in addition, due to a change in the flow direction angle from c to c, they fall by gravity and are supplied to the coal crushing section 30. In other words, in the state shown in Figure 3B,
When the amount of primary air is increased from the amount of air in the state shown in Figure A _{and a1} is set to a, the guide vane 52 is conveyed.
The particle size distribution of the pulverized coal flowing into the pulverized coal is approximately similar to that shown in FIG. 3A.

On the other hand, if the throat plate 101 is set at _a γ angle with respect to the slit plate as _shown in _FIG . The primary air flow becomes _c2 . (See Figure 3A) In this way, primary classification can be achieved by changing the mounting angle of the slit plate and the slot plate to change the velocity and flow direction of the primary air flow to correspond to the flow rate of primary air for combustion required for the boiler load. can maintain a high level of effectiveness.

By implementing this invention, the direction of air supply to the crushing section and the amount of air supplied from the throat can always be maintained appropriately, so a high classification rate can always be obtained regardless of the load on the crusher.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional ball mill, Fig. 2 is a sectional view of an apparatus according to the present invention, Fig. 3A shows the primary air flow at the throat and the flow c through the slit, Fig. 3B, and Fig. 3C. _Fig . _3B is a drawing schematically showing the primary air flow c1 when the mounting angle of the slit plate is β, and Fig. 3C is a drawing schematically showing the primary air flow _c1 when the mounting angle of the throat plate is changed. ₂ is a drawing schematically showing the flow c2 when 100... Slit plate, 101... Throat plate, 106, 113... Rod, 109, 114
...Cylinder, 110,115...Ball bearing.

Claims (1)

[Claims] 1. A throat section is defined between the end of the slit plate and the outer periphery of the lower ring of the coal crushing section, and the pulverized material such as coal is pulverized by primary combustion air supplied from the throat section and the slits of the slit plate. 1. A variable throat crushing and classifying device for primary classification, characterized in that it is equipped with a device for rotationally displacing a slit plate hinged to the device body. 2. A variable throat portion according to claim 1, characterized in that a throat plate is attached to the slit plate by a hinge, and a device is provided for adjusting and changing the attachment angle between the slit plate surface and the throat plate surface. Type crushing classifier. 3. Claims characterized in that the rod is engaged with the slit plate and/or the back surface of the slot plate, and the attachment angle of the slit plate and/or throat plate is adjusted by moving the rod in and out of the wall surface of the main body of the device. Paragraph 1 or 2
Variable throat type crushing and classifying device as described in 2. 4. The variable throat pulverizer according to any one of claims 1 to 3, wherein the rod is supported by a ball bearing and connected to a cylinder operated by a working medium such as hydraulic pressure. Classifying device.