RU2083459C1 - Pneumatic transport installation for vacuum reloading of powder material from container into package with small-size filling neck - Google Patents

Abstract

FIELD: materials transportation; pneumatic transport installations of suction-and-delivery type providing closed dustless reloading of powder materials from transportation container into package with small-size filling neck. SUBSTANCE: installation has vacuum pump, external and internal hoppers, filter, suction and delivery pipelines. Taper shutoff member arranged on discharge neck of outer hopper has projecting supply pipeline mounted inside shutoff member with circular clearance communicating with inner hopper space through branch pipe whose outlet is made in form of volute and is located on discharge neck of inner hopper equipped, in its turn, with cylindrical damper. Angle of tilting of wall of inner hopper funnel is smaller than that of outer hopper. EFFECT: enlarged operating capabilities. 2 cl, 3 dwg

Description

 The invention relates to pneumatic conveying installations of the suction-discharge type, the use of which provides a closed and dustless overload of powdered bulk materials from containers in containers with a small inlet.

 Known pneumatic feeder for automatic reloading of bulk materials, containing a vacuum pump, external with an outlet funnel and internal bins, a filter, suction and discharge pipelines and a shutter on the discharge neck of the outlet funnel of an external hopper.

 However, this design is very unproductive when overloading the material in a container with a small inlet.

 The capacity of the known feeder is controlled by a valve-gate, depending on the magnitude of the vacuum and the elasticity of the rubber. But this does not at all take into account the factor of the smallest permissible size of the through-hole, which ensures unhindered passage of material through it (see RL Zenkov, II Ivashkov, LN Kolobov. Continuous Transport Machines. M. Mechanical Engineering, 1987, p. 386, 4.114 formula of K.V. Alferov or in the same place, p. 377, formula 4.88). Failure to comply with this condition when backfilling material in a container with small inlet openings (for example, of the order of 12.14 mm) leads to pipe formation and arching of the material in front of them.

 The latter is explained by the fact that the normal stress at sites perpendicular to the arch line for bound loads can be zero without disturbing the balance of the loose body. Such a stress state occurs when the outlet of the hopper (or inlet of the feed tank) is less than the maximum arch-forming opening.

 When the height of the arch becomes comparable with the depth of the hopper, the phenomenon of tube formation occurs. A hollow pipe forms above the discharge opening, and further material movement stops.

 To eliminate these phenomena, one has to apply shurovye operations, striking the bunker and vibrating. The implementation of these operations is associated with significant design complications, the addition of drives and, as an inevitable consequence, a loss of productivity.

 The known design has drawbacks in the possibility of obstacles in the way of the transported material from the material itself when it is overloaded in a container with a small inlet, which practically eliminates the feeder from the duty cycle.

 The objective of the invention is to increase productivity.

 The technical result consists in the exclusion of pipe and arch formation in front of the inlet of the tank.

 This is achieved by the fact that in a pneumatic conveying system for vacuum loading powder material from containers into containers with a small loading neck containing a vacuum pump, an external one with an outlet funnel and internal bins, a filter, a suction and discharge pipelines and a shutter on the discharge neck of an outlet funnel of an external bunker , the inner hopper is equipped with an outlet funnel, and the shutter on the discharge neck of the outlet funnel of the outer hopper is made in the form of a capacitively interacting with the feed neck the cone and is provided with a supply pipe protruding from it, mounted inside the shutter with an annular gap communicating with the cavity of the inner hopper by means of a pipe, the outlet end of which is curved in the shape of a snail and is located in the discharge neck of the outlet funnel of the inner hopper, equipped with a damper in the area of this neck, made in the shape of a cylinder. Moreover, the angle of inclination of the funnel wall of the inner hopper may be less than the angle of inclination of the funnel wall of the outer hopper.

 In FIG. 1 shows a general view of the installation; in FIG. 2 type A shutter; in FIG. 3 section BB shutter.

 The installation consists of a vacuum pump 1, which is connected to the suction pipe 2 of the outer 3 and inner 4 bins with funnels 5 and 6, respectively.

 In the upper part of the external hopper 3 there is a discharge pipe 7, a self-shaking filter 8 mounted on a frame 9 suspended on a spring 10. On the outlet neck of the external hopper 3 there is a conical shutter 11 with a feed pipe 12 protruding from it, mounted inside the shutter 11 with an annular gap 13, communicating with the capacity of the inner hopper 4 through the pipe 14, the output of which is made in the form of a snail 15 and is located on the outlet neck of the inner hopper 4, equipped with a cylindrical damper 16.

 Installation works as follows.

 The loading container 17 is placed under the shutter 11, the cone of which, when interacting with the opening of the container, creates a sealed volume that is uniform with the internal cavity of the installation. At the same time, a command is issued to turn on the vacuum pump 1 and through the suction pipe 2 and the annular gap 13 of the nozzle 14, air is removed from the cavities of the bins 3, 4 and the tank 17. The created vacuum stimulates the flow of powder material from the container through the discharge pipe 7 into the hopper 3 and further into capacity 17 through the pipeline 12.

The reliability of the installation is ensured as follows. The tangential entry of the powder flow through the pipeline 7 into the external hopper 3 when interacting with the upward flow of air causes the rotation of the powder-air mixture. Powder particles moving in a rotating curved air stream are under the influence of gravity, centrifugal force and drag force. The structural elements of the installation provide the most effective effect of these forces on the powder particles for its unhindered entry into the loadable tank. So, as a result of the action of centrifugal forces, powder particles suspended in the stream are thrown onto the walls of the external hopper 3 and fall out of the stream. To ensure continuous expiration of this mass of powder, the walls of the funnel 5 are made at an angle greater than the angle of collapse of the material, depending on the particle size of the material, its bulk density, flowability, and external friction coefficient. As a rule, this angle is 70-80 ^o . The action of the vacuum also helps to accelerate the flow of powder to the outlet neck of the external hopper 3. Part of the powder, which, under the discharge pressure through the discharge pipe 7, tends to the axis of the hopper 3, is also thrown down due to the interaction with the inclined wall of the funnel 6 of the internal hopper 4. Next, the powder is piped 12 enters the tank 17, from which air is sucked out simultaneously through the annular gap 13. To exclude the reverse flow of powder particles by the air flow, the pipe 12 is protruding from the shutter 11, and its output is in the form of a snail 15. The output of the pipe 14 in the form of a snail 15 allows for constant dynamic pressure at its inlet, eliminating the influence of pulsations of the dusty air flow and thereby increasing the vacuum in the tank 17.

 The location of the outlet of the pipe 14 on the outlet of the inner hopper 4 allows you to use the ejector effect of the outflow of air through it to increase the vacuum in the tank 17 by creating a deeper air discharge at the outlet of the pipe 14.

 At the bottom of the hopper 3, a peculiar tornado forms, its fifth resting on a layer of powder. Those. a phenomenon occurs that is similar to the effect of atmospheric vortices on objects located on the ground. At the same time, in the center of the tornado, the helical motion of the powder particles is directed upward, and centrifugal forces tend to increase the area of this flow. In order to exclude the effect of this flow on the downflow of the powder, a cylindrical damper 16 is mounted on the neck of the hopper 4, which concentrates the flow in its volume and directs it further to the inner hopper 4. Under the action of centrifugal forces, the powder particles are thrown onto the walls of the funnel 6, drop out of the flow and enter through the outlet of the inner hopper 4, the damper 16 to the outlet of the outer hopper 3.

To exclude the formation of arches, the rate of outflow of powder from the inner hopper should be less than the rate of outflow from the outer hopper. This is achieved by performing the ratio of the angles of inclination of the walls of the funnels of the inner and outer bins ∠β int _. <β _ext.
In order for the part of the powder entrained in the upflow not to enter the discharge system, a filter 8 is located in front of the suction pipe 2, having a shaking device consisting of a spring 10 and a frame 9, which returns the powder to the charge.

 The total effect of the described effects of structural elements on the powder, as well as the difference in vacuum pressure between the cavities of the bins 3, 4 and the loading tank 17 provides unhindered flow of the powder into the container during overloading.

 The geometric parameters of the installation design, namely, the size of the annular gap 13, the diameter of the pipe 12, the diameter and height of the cylindrical damper 16, the height of the funnel 6 of the inner hopper 4, the angles of inclination of the walls of the funnels 5, 6, are very complex calculations (see ibid., P. 343-360).

 The initial data for the calculations are the specific properties of each specific material, namely, the size of its particles, their bulk density, flowability, external friction coefficient, which in turn depend on such specific properties of the material as brittleness, hygroscopicity, caking, freezing, etc. .

Claims (2)

 1. Pneumatic conveying installation for vacuum transfer of powdered material from containers into containers with a small loading neck, comprising a vacuum pump, an external one with an outlet funnel and internal hoppers, a filter, a suction and discharge pipelines and a shutter for the discharge neck of an outlet funnel of an external hopper, characterized in that the inner hopper is equipped with an outlet funnel, and the shutter on the discharge neck of the outlet funnel of the outer hopper is made in the form of a container interacting with the feed neck the cone and is provided with a supply pipe protruding from it, mounted inside the shutter with an annular gap communicating with the cavity of the inner hopper by means of a pipe, the outlet end of which is curved in the shape of a cochlea and located in the discharge neck of the outlet funnel of the inner hopper, provided in the area of this neck with a damper made in cylinder shape.  2. Installation according to claim 1, characterized in that the angle of inclination of the funnel wall of the inner hopper is less than the angle of inclination of the funnel wall of the outer hopper.

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