RU2226492C1 - Device for settling multifractional loose materials - Google Patents

Abstract

FIELD: pneumatic transportation of loose materials. SUBSTANCE: proposed device has settler with housing, inlet branch pipe, cover, sectional aeroslide bottom and shell limiting separating zone, cyclone connected with settler through suction and provided with sluice lock whose discharge branch pipe communicates with space of settler and line to deliver compressed air into each section of aeroslide bottom. Discharge branch pipe of sluice lock is introduced into settler cover over inlet branch pipe, and shell limiting separating zone is connected with suction volute by gradually narrowing conical attachment. Each section of aeroslide bottom in place of connection with compressed air delivery line is furnished with shutoff-bleeder valve. Said valve consists of split housing provided with exhaust holes connecting sections of aeroslide bottom with atmosphere, freely fitting diaphragm over lapping exhaust holes in process of transportation of powder, and membrane overlapping exhaust holes in process of air delivery into aeroslide bottom, said membrane being clamped over and provided with central hole. EFFECT: reduced carry-over of transported powder mixture, preservation of fraction al composition. 2 cl, 4 dwg

Description

The invention relates to pneumatic transport of bulk materials, in particular to unloaders used in pneumatic transport of working powder mixtures in technological complexes of mixed solid fuel production, and can be used in other industries.

Known devices for the deposition of bulk materials, including a precipitator with an airlift and a cyclone connected in series with it, from which the captured material is returned to the precipitator. In the pneumatic conveying systems used at a number of enterprises developed by the FSUE "NIIPM" company in Perm, a device is used to separate the transported powder from the carrier air (see Figure 1), consisting of a precipitator and a cyclone. The known precipitant includes a cover 1, body 2 and an aerodrome 3. Inside the body 2 there is a shell 5 welded to the cover 1. The air mixture enters the annular gap between the body 2 and the shell 5 along the tangential pipe 11. The flow moves first downward, and then, reaching the lower edge of the shell, makes a rotation of 180 °. In this case, the powder is separated from the air. Air through the cylindrical pipe 10 and the cochlea 9 is sent for secondary cleaning to the cyclone 8, in which the remaining particles of the powder are captured in the air stream. The powder captured in the cyclone from the cyclone by the lock gate 7 is returned to the precipitator through the discharge pipe 6.

This device, adopted by the authors as a prototype, has been successfully used for a long time at the enterprise of FSUE Perm Kirov Plant. However, products have recently appeared for the manufacture of which working mixtures of powders with a high content of finely dispersed fraction (with a particle size of less than 5 microns) are used. When working with these powders, a number of significant disadvantages of this device were identified.

Firstly, in this device there is a violation of the fractional composition of the transported mixture of powders. This is due to the fact that more than 1% of the transported mixture is carried away into the cyclone, and the powder captured in the cyclone consists of the smallest particles. When this powder is returned to the precipitator by a lock, the discharge takes place only in one place, while the averaging ability of the precipitator is small.

Secondly, when using this device to precipitate a mixture of powders with a high content of fine fractions, significant ablation of the latter is observed. This is because, for the deposition of fine particles, the height of the separation zone must be sufficient to equalize air velocities. In this design, air from the separation zone is sucked out through a cylindrical pipe 10, the diameter of which is several times smaller than the diameter of the shell 5. For this reason, when the air passes from the separation zone to the pipe 10, its speed gradually increases. In this case, a zone of increased air velocities is formed, having the shape of a cone, the opening angle of which is about 60 °. The smallest particles of the transported mixture, falling into this zone, are carried out by a stream of air from the precipitator. Therefore, the presence of the specified zone of increased speeds significantly reduces the actual height of the separation zone, and therefore increases the entrainment of the transported powder.

A simple increase in the actual height of the separation zone leads to an increase in the total height of the deposition device, which, in turn, leads to significant capital costs for the construction of higher buildings and embankments.

Thirdly, the precipitator airfield 3 of the prototype under consideration is equipped with a rubber gas distribution partition 4, which has openings that open only after the partition is inflated. To unload bulk material, compressed air is supplied under the gas distribution partition periodically according to a predetermined program. In this case, the partition is first inflated, eliminating the freezing of the material, and then the passage of air from the openings into the powder layer begins, thereby conducting aeration and unloading of the material from the precipitator.

After stopping the supply, compressed air must be vented from under the partition so that it returns to its original position and does not interfere with the discharge of the powder. Venting through the valve supplying compressed air is not permissible for safety reasons. Therefore, small holes were made in the bottom that allow the gas distribution partition to return to its original position. But this increased the consumption of compressed air and reduced the reliability of the partitions, since during transportation, when rarefaction is created in the precipitator, atmospheric air entered through the openings under the partition and the partition was inflated. In addition, as a result of inflation, the openings of the gas distribution partition are opened and air is sucked in from the atmosphere, which leads to an increase in air velocities in the precipitator and increased entrainment of the transported powder.

The technical task of this invention is to maintain the fractional composition and reduce the entrainment of the transported mixture of powders.

The technical result is achieved due to the fact that in the proposed device the discharge pipe of the cyclone is mounted on the cover of the precipitator above the inlet pipe in the area of the flow of the mixture entering the precipitator, which distributes the powder returned from the cyclone over the entire cross-section of the precipitator. The shell limiting the separation zone is connected to the cochlea of the air suction by a smoothly tapering nozzle, which ensures the design speed of the separation zone that is the same over the entire height.

In addition, each section of the aerodrome is connected to the compressed air supply line and to the atmosphere through a shut-off and bleed valve, consisting of a detachable body having exhaust openings. Exhaust openings during powder transport are blocked externally by a free-fitting diaphragm. The same holes during the supply of compressed air to the aerodrome are blocked from the inside by a membrane clamped around the periphery, which has a central hole. During the bleeding of air from under the aerodnick, the exhaust openings are not covered by anything and the air freely escapes into the atmosphere.

Figure 1 schematically shows a General view of the prototype; figure 2 is a General view of a device for the deposition of multifractional bulk materials; figure 3 is the same, a top view; figure 4 - node 12 of figure 2.

The device for the deposition of multifractional bulk materials (see figure 2) includes a precipitator consisting of a cover 1, a housing 2 and an aerodrome 3. A cyclone 8 is connected in series with the precipitator 8 with a lock gate 7. A cyclone with a shutter is mounted on the precipitator cover and connected to the precipitator cavity through the discharge pipe 6.

On the cover of the precipitator, a shell 5 is fixed, which limits the separation zone. The separation zone is connected to the outlet cochlea 9 with a smoothly tapering nozzle 10. The presence of such a nozzle makes it possible to maintain the calculated air flow velocity over the entire height of the shell 5, where the main part of the powder is deposited, including its fine fraction. Thus, while maintaining the overall dimensions of the device, the height of the separation zone increases, and therefore, the entrainment of the transported powder decreases.

In the upper part of the housing 2 there is (see FIG. 3) an inlet pipe 11 that provides tangential introduction of the air mixture into the precipitator. Moreover, the inlet pipe is located under the discharge pipe 6 (figure 2), which ensures the return of the powder from the cyclone 8 directly into the stream of the mixture entering the precipitator.

The airliner 3 is a truncated cone, equipped with a rubber gas partition 4, which has holes that open only after inflation. The gas distribution partition is designed for collapse and giving the powder fluidity during unloading. The space between the bottom housing and the gas distribution partition is divided into three horizontal sections, each of which provides for a periodic supply of compressed air in a predetermined sequence. The frequency and duration of the compressed air supply is determined empirically, depending on the properties of the powder.

To bleed air from under the gas distribution partition after stopping the supply of compressed air and to prevent suction of atmospheric air when rarefaction occurs inside the precipitator when the pneumatic conveying operation of the powder is carried out, a shut-off valve 12 is provided in each section of the aerodrome.

The shut-off and release valve (see Fig. 4) is a detachable housing 13, in which, in addition to the compressed air supply opening, there are exhaust openings for discharging compressed air from under the gas distribution partition after its supply is stopped. In the connector of the housing 13, a membrane 14 is clamped around the periphery, which bends and closes the exhaust openings when compressed air is supplied to the aerodynamic plate, and after the air supply ceases, it returns to its original position, closing the compressed air supply openings and opening the exhaust openings.

A diaphragm 15 lies freely on the exhaust openings, which does not interfere with the release of compressed air from under the gas distribution wall into the atmosphere, but overlaps the openings when rarefaction occurs in the precipitator. This prevents the suction of atmospheric air during transportation, and therefore, increased entrainment of the powder.

To prevent excessive diaphragm withdrawal during air bleeding, a disk stop 16 is installed on the housing.

A device for the deposition of multifractional bulk materials works as follows.

When transporting the aerosol mixture of bulk materials through the tangential inlet pipe 11 (Fig.3) enters the annular space between the housing 2 (Fig.2) and the shell 5. In this space, the aerosol mixture loses speed and falls down into the main dust settling space, where the air velocity reaches a minimum quantities and the main part of the transported material settles. The air together with the non-settled particles of the powder enters the separation zone and rises up. In this zone, the calculated air velocity is less than the velocity of the minimum particle. Therefore, the particle deposition process also continues here. However, due to turbulence and turbulent motion in this zone, not all particles fall out of the air stream. Part of them (about 1%) enters the smoothly tapering nozzle (i.e., in the zone of increased speeds) and is carried out together with air through the outlet scroll 9 from the precipitator to the cyclone, where additional air purification from suspended particles occurs. The air from the cyclone enters the final purification system, and the captured powder by the lock gate 7 continuously returns to the precipitator through the nozzle 6, is picked up by the air mixture, distributed throughout the precipitator, and precipitated together with the main stream. During transportation, compressed air is not supplied to the aerodrome, the exhaust openings of the shut-off and bleed valve are blocked by a diaphragm 15.

After the transportation operation is completed, the device for the deposition of multifractional bulk materials serves as a consumable capacity of these materials in the technological line for the preparation of STRT. At the same time, the lock of the cyclone is stopped, and compressed air is supplied to the powder section through the shutoff-bleed valves in order to facilitate the discharge of powder through the shut-off and bleed valves.

The placement of the discharge pipe with a cyclone and a lock gate installed on it above the inlet pipe allows you to distribute the powder returned from the cyclone throughout the precipitator, and therefore, reduce the fractionation of the powder.

The connection of the shell limiting the separation zone with the outlet cochlea of the precipitator smoothly tapering nozzle allows you to remove the zone of high air velocities from the separation zone, and therefore, to reduce the entrainment of the powder.

The presence in the shut-off and bleed valve of exhaust openings blocked by a free-lying diaphragm, and a membrane clamped along the contour, which overlaps the exhaust openings when compressed air is supplied and releases them when compressed air is drained, can reduce powder entrainment and prevent gas distribution partition ruptures during powder transportation to the precipitator.

A pilot industrial model of the proposed device for the deposition of multifractional bulk materials has been tested in industrial conditions with positive results. In the future, it is planned to use it in pneumatic transport installations at the STRT production.

Claims (2)

1. A device for the deposition of multifractional bulk materials containing a precipitant having a housing, an inlet pipe, a cover, a sectional airstrip and a shell defining a separation zone connected to the precipitator through a suction snail cyclone with a lock gate, the discharge pipe of which communicates with the precipitator cavity, and a compressed air supply line to each section of the aerodrome, characterized in that the discharge gate of the airlock is introduced into the precipitator cover above the inlet, a shell limiting sep Discount zone connected to suction scroll smoothly tapered conical nozzle, each aerodnischa section at the connection to the compressed air supply line provided with a shut-bleed valve. 2. The device according to claim 1, characterized in that the shut-off and release valve consists of a detachable housing having exhaust openings connecting the airfoil sections to the atmosphere, a free-fitting diaphragm that covers the exhaust openings during powder transportation, and a membrane that closes the exhaust openings during the supply of air to the aerodrome, and the membrane is pinched on the periphery and has a Central hole.

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