JPH03217249A - Vertical type grinder - Google Patents

Abstract

PURPOSE:To perform operation wherein the minimum load of a grinder is more lowered by adopting a rotary throat and controlling at least one side of the cross-sectional area for passing air provided to a grinding table side and the same provided to a housing side in a range over the whole circumference and also in the partial part. CONSTITUTION:This grinder is provided with a grinding part and a throat 1 described below respectively. In the grinding part, solid to be ground is introduced from the upper part of a housing 5 and ground by a rotary grinding table 11 and a plurality of rollers positioned thereon. The throat 1 consists of the throat group upward opened in, the outer circumference of the grinding table 11 or the throat blade group. At least one side of a cross-sectional area controlling body 2 of an air feed port and a cross-sectional area controlling body 10 thereof is provided as a split system capable of being controlled in a range over the whole circumference and also in the partial part. The controlling body 2 is provided to the housing 5 side of the throat 1 and fixed to the housing. The controlling body 10 is provided to the grinding table 11 side of the throat 1 and fixed to the grinding table 11. As a result, operation is performed wherein the minimum load of the grinder is more lowered. Further operation is performed wherein the concn. of a product is made higher than heretofore and the pressure difference of the grinder is made lower.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulverizer, and particularly to a vertical pulverizer suitable for reducing particles falling down the throat.

[Conventional technology]

FIG. 6 shows a longitudinal sectional view of a conventional vertical crusher.

The pulverizer is composed of a driving section 16, a pulverizing section 17, and a classifying section 18.

The solids to be crushed, which are supplied from the central part of the crusher, fall from the solid supply pipe 19 and are sent out to the outer periphery under centrifugal force on the crushing table 11, which is rotated by a drive section 16 consisting of a motor 20 and a speed reducer 21.

The solid is crushed by compression and abrasion between a plurality of crushing roller tires 22 whose shafts are movable in the axial direction of the crushing table 11 and the crushing table 1l, and further advances toward the outer periphery.

The finely divided solid is heated by hot air a supplied from the throat 1 provided between the outer periphery of the crushing table 11 and the housing 5.
It is blown up inside and above the housing 5 while being dried.

Among the particles blown up, coarse particles fall because the gravity acting on them overcomes the buoyant force. This is the primary classification (gravity classification)
It is called. Particles that were not separated in the primary classification reach the rotary classifier 18 at the top of the crusher, and due to the balance between centrifugal force and drag, and the balance between the inertia and drag applied by being struck by the classification blades 23, only coarse particles are left. Fall. This is called secondary classification. In addition to the rotary classifier 18, a cyclone classifier is usually employed in the secondary classification section.

The fine particles that have passed through the primary classification section and the secondary classification section are
The product is sent out from the pipe 24 at the top of the pulverizer as a fine powder, and the other particles are returned to the pulverizer 17 after falling and are re-pulverized.

The amount of particles that pass through the crushing section 17 and are blown up to the top of the throat 1 per unit time, that is, the sum of the amounts of supplied solids and re-pulverized particles per unit time (pulverizing section circulation amount) is several times the solid supply flow rate. The upper part of the throat 1 becomes a fluidized bed.

If the fluidized bed formed at the upper part of the throat 1 contains foreign particles with a high specific gravity, the buoyancy force due to the hot air a from the throat 1 acting on the foreign particles and the gravity become unbalanced, and the particles fall to the lower part of the throat 1. . Furthermore, if the buoyancy is extremely small, the solid to be crushed will also fall. These fallen particles are collected by a plow 25 attached to the lower part of the crushing table 11 and discharged out of the system through a falling particle passage 26.

In normal operation of a crusher, the ratio of solids feed rate to air feed rate is approximately 1:2 to 1:3, and when reducing the crusher load, that is, when reducing the solid feed rate, the air feed rate may be reduced. It is set to decrease in proportion to approximately 1/2 power of the amount of solids supplied. When the load of the crusher drops to about 40% of the rated value, the supplied air amount becomes about 63% of the rated value, and the throat 1
The flow rate of the air passing through the throat 1 decreases, and as described above, the buoyant force decreases, causing a phenomenon in which even particles other than foreign objects fall down the throat 1. Furthermore, when the load is high, even if the load is 40% or more, the amount of circulation in the crushing section increases depending on the operating conditions, and the balance between gravity and buoyancy is disrupted, causing a similar phenomenon.

On the other hand, the reason for the increase in the amount of falling particles is that the crushing table 11
Examples include uneven flow of particles at the upper throat in the circumferential direction (non-uniform concentration) and an accompanying imbalance in the flow velocity passing through the throat. This imbalance locally increases the number of falling particles in areas where the flow velocity is low. While the required air flow velocity at each circumferential position of the throat l is theoretically several m/s,
In order to raise the local minimum flow velocity value to the required air flow velocity value, in the actual machine, the average air flow velocity value is increased by 1.
The speed is set to several tens of m/s, which is an order of magnitude higher.

Figure 7 shows a first example of a conventional throat structure (Figure 8 shows its C
C sectional view) is shown. This throat Ia includes a housing 5,
The cross section surrounded by the throat blade 7 and the throat inner ring 27 is formed by a group of cylinders having a rectangular shape. This throat is called a fixed throat.

FIG. 9 shows a second example of a conventional throat structure (FIG. 10 is a DD sectional view thereof). The present throat lb has a shape in which a plurality of throat blades 7 are attached to the circumferential portion of the crushing table 11, and there are some cases in which the outer side of the throat blades 7 is covered with a throat outer ring 8, and some cases in which the outer side of the throat blades 7 is not covered. Since the main throat lb rotates together with the grinding table 11, it is called a rotating throat in contrast to the fixed slot 1a. The inclined direction of the throat blade 7 in the circumferential direction is the same as that of the crushing table 11.
This is opposite to the 0 rotation direction.

In the case of rotational throw} 1b, the solid particle density at the upper part of the throat 1 is made uniform by rotation, and there is a pressure increasing effect based on the same principle as an axial flow fan, so compared to the case of fixed throw} 1a, the amount of falling particles is The load factor of the crusher can be lowered (approximately 30% load). Examples of this type of device include Japanese Patent Application Laid-Open No. 60-064645,
Examples include Japanese Utility Model Application Publication No. 144548/1983.

[Problem to be solved by the invention]

Among the conventional technologies mentioned above, in the case of a fixed throat, there are concerns about the increase in the amount of particles falling to the bottom of the throat under low-load operation of the crusher or operating conditions with a large amount of circulation in the crusher (for example, operation with high product concentration), and the possibility that particles at the upper part of the throat No consideration was given to the local increase in the amount of falling particles caused by the uneven flow of the air and the imbalance in the flow velocity passing through the throat, and there was a problem in that the increased amount of falling particles limited the operational conditions.

On the other hand, in the case of a rotating throat, although the amount of falling particles is improved compared to a fixed throat, there is a problem that the number of falling particles increases again when the crusher load factor is further lowered (from 30% to 15%).

An object of the present invention is to enable operation with a lower minimum load on the pulverizer, and operation with a higher product concentration and lower differential pressure of the pulverizer than in the past.

[Means to solve the problem]

The above purpose is to use a rotating throat, and to make the air passage cross-sectional area of the throat adjustable over the entire circumference and partially on at least one of the crushing table side and the housing side, and to use the area adjustment member to minimize the flow. This is achieved by creating a shape that does not

[Effect]

According to the air passage cross-sectional area adjustment mechanism of the throat, the air passage cross-sectional area is reduced over the entire circumference when the normal crusher is operated at a lower minimum load rate or when high concentration operation is required. You can set it as you like. The throat air velocity is thereby increased so that fewer particles fall down the throat.

In addition, with the air supply port cross-sectional area adjustment mechanism fixed to the housing, the particle concentration in the circumferential direction of the grinding table, which could not be divided uniformly by the conventional rotating throat, can be locally adjusted using the same mechanism. It is possible to suppress the amount of particles falling down the throat, and the overall amount of falling particles does not increase.

[Embodiments of the invention]

The throat structure of the embodiment is shown in FIGS. 1 to 4. 1st
The figure shows an example of an air supply port cross-sectional area adjuster fixed to the housing, FIG. 2 is an AA cross-sectional view, FIG. It is a BB sectional view.

The overall configuration of the crushing section is the same as that of the prior art except for the throat section. The throat portion of the present invention is fixed to the crushing table side. That is, the aforementioned "rotating throat".

In FIG. 1, the cross-sectional area of the air supply port of the throat 1 can be adjusted by moving a cross-sectional area adjuster 2 in and out of the housing radially using a shaft 3 as a fulcrum. This operation can be performed from outside the crusher via the adjustment rod 4. Moreover, since the cross-sectional area adjuster 2 is installed in plural pieces in the circumferential direction of the housing 5, it is possible to locally adjust the cross-sectional area S. If there are many falling particles from throat 1 over the entire circumference, set S to be small over the entire circumference, and if there are many falling particles locally, set S at that part.
Set to make it smaller.

The surface 6 of the cross-sectional area adjuster 2 on the center side of the crusher and the surface of the housing 5 on the center side of the crusher (or if the throat outer ring 8 is installed on the throat blade 7, the surface of the ring on the center side of the crusher) ) is 06 to 2 in consideration of fluid resistance.
As a method of operating the cross-sectional area adjuster, in addition to the rotary movement method around the shaft 3 as in this embodiment, a parallel movement method in the radial direction of the housing cylinder can be considered.
When partially adjusting the cross-sectional area of the upper side of the throat 1, the former is preferable from the viewpoint of reducing fluid resistance.

In FIG. 3, the cross-sectional area of the air supply port of the throat l can be adjusted by moving the cross-sectional area adjuster 10 in and out of the crushing table 11 in parallel with the radial direction. In the case of fixing with bolts 12 and 13 as in this example, this operation cannot be adjusted while the crusher is in operation, so it is used only for rough setting of the throat area during trial operation, and fine adjustments are made as described above. It is preferable to use the cross-sectional area adjuster 2 shown in FIG.

Another embodiment of the invention is shown in FIG.

In this embodiment, the air supply port cross-sectional area adjuster 2.10 is attached to both sides of the housing 5 and the crushing table 11, and the adjuster 2 on the housing 5 side is located approximately in the axial direction of the throat 1. The entire structure is adjustable. The cross-sectional area adjusting body 2 is divided in the circumferential direction by a throat blade 7a fixed to the housing.
The division is performed by a throat blade 7b fixed to the crushing table.

According to this embodiment, since the cross-sectional area S of the throat 1 can be set almost uniformly in the throat axial direction, an increase in the pressure loss coefficient of the fluid due to a reduction in the cross-sectional area can be suppressed to a minimum. Further, by setting the cross-sectional area S uniformly in the throat axis direction, the amount of falling particles can be reduced compared to a case where the cross-sectional area S is set only partially.

(゜．゜If the cross-sectional area is partially reduced, it is possible to increase the flow velocity in that part, but once the particles reach the bottom of the part where the flow velocity is high, they start falling all at once.
When the cross-sectional area is uniformly reduced in the throat axial direction, the part where the flow velocity is high is long, so even if the particles reach the middle part of the throat, for example, they can be prevented from proceeding further downward. ) Another advantage of this embodiment is that the throat area S can be divided into the fixed throat area Sa and the rotating throat area sb, and the ratio can be set arbitrarily, so the effect of the rotating throat ib can be adjusted using this ratio. be.

〔Effect of the invention〕

According to the present invention, since the cross-sectional area of the throat can be arbitrarily adjusted around the entire circumference or locally, the following effects can be obtained.

(1) Since it is possible to reduce the amount of particles falling down the throat when the crusher load is low, the conventional minimum load rate can be further lowered.

(2) In operation where the amount of circulation in the crushing section inside the crusher is large (for example, high concentration operation), the amount of falling particles has conventionally been large and operation has been difficult, but the reduction in the amount of falling particles makes it easier to operate.

(3) It is possible to reduce the capacity of the falling particle collection system.

(4) If the supplied solid is flammable (such as coal), there is a risk of ignition from the falling particle collection system, but the risk is reduced because the absolute amount of falling particles can be kept low.

(5) It is possible to locally adjust the throat cross-sectional area and keep the air flow velocity and particle concentration almost constant over the entire circumference, which is advantageous for throat wear.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the throat structure (air supply port cross-sectional area adjuster fixed to the housing) according to the present invention, FIG.
FIG. 4 is a BB#r side view thereof, FIG. 5 is a diagram showing still another embodiment of the throat structure according to the present invention, 6th
The figure is a vertical sectional view of a conventional vertical crusher, FIG. 7 is a diagram showing a conventional throat structure (fixed throat), and FIG. 8 is a diagram showing the conventional throat structure (fixed throat). 1... Throat, la... Fixed throat, 1b...
・Rotating throat, 2, 10...Cross-sectional area adjusting body, 5...
-Housing, 11...Crushing table, 17...Crushing section, 22...Roller tire. Figure 1 Figure 2 Figure 3 Figure 5 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] A crushing section that crushes solids to be crushed, which are introduced from the upper part of the housing, using a rotating crushing table and a plurality of rollers located on the rotating crushing table, and a throat consisting of a throat group or a throat blade group that opens upward on the outer periphery of the crushing table. In the vertical crusher, at least an air supply port cross-sectional area adjuster fixed to the housing provided on the housing side of the throat, and an air supply port cross-sectional area adjuster fixed to the crushing table provided on the grinding table side of the throat. A vertical crusher characterized in that one side is installed as a divided system that can be adjusted partially over the entire circumference.