RU2378037C1 - Bag filter for dust trapping - Google Patents

Abstract

FIELD: treatment facilities.

SUBSTANCE: invention is intended for trapping of dust from gases and may be used to clean air in various industry fields. Filter comprises body with cover, nozzles for inlet of gas for cleaning and outlet of cleaned gas, device for dust unloading, discharge cavity arranged under filter cover and pressurised with blowdown air, filtering bags installed in filter body, one or several distribution cavities with one control valve for each cavity, which provide for simultaneous blowdown of several filtering bags, at the same time distribution cavities and control valves are arranged in discharge cavity of filter. As control valves they use electromagnetic or pneumatic valves.

EFFECT: reduced costs for structure used to blowdown filtering bags, increased efficiency of filter and its reliability in operation.

2 cl, 3 dwg

Description

The invention is intended for the purification of air from dust and other fine particles and can be used in various industries, including at high temperatures of the cleaned air.

There are various designs of bag filters used to clean gases from dust.

Known bag filter of the Swiss company "Gebruder Buhler AG", consisting of a housing divided by a partition into a chamber for polluted and a chamber of purified air. In the chamber for contaminated air to be cleaned, porous fabric filter bags are placed with a filtering direction from the outside to the inside of the bags. Venturi tubes are placed in the purified air chamber for pulse purging of the hoses with compressed air, which is supplied from the container for compressed purge air. The filter is equipped with nozzles for supplying air with dust to the filter for cleaning and removing purified air from it, a device for pulsed purging of bags with compressed air in the opposite direction of filtration, valves for reverse purging and a device for controlling the duration and frequency of pulses. The bottom of the filter is made in the form of a cone-collector with a lock gate to collect dust delayed by the filter bags and to remove it from the filter (1).

According to RF patent No. 2191061 for invention (2), the patent holder of Dzerzhinskhimmash OJSC, a bag filter for dust removal of gases contains a cylindrical body with a lid, an inner lining on its side surface and a conical bottom-collector for transporting trapped dust to the gate lock. The filter housing is divided by a partition into chambers of clean and dusty gas. Filter bags are located in the dusty gas chamber, each of which is made in the form of a wire frame and a filter cloth worn on it. In the clean gas chamber there is a nozzle for the outlet of the purified gas, a box for compressed purge air and membrane valves of the pulsed reverse purge system of the filter bags, as well as mounted on the partition coaxially with the venturi valves (according to the number of bags), the lower ends of which enter the chamber through the partition dusty air and on which frames of sleeves with filter cloths are fixed. The housing has a tangential nozzle for introducing gas into the dusty gas chamber and is equipped with an explosive discharge device mounted on the housing fitting in the dusty gas chamber above the conical trapped dust collector equipped with an air hammer on the outside. Between the housing and the bottom-collector there is a grill, which serves to mount the sleeves and to prevent the falling of the sleeves in the lock gate. Each diaphragm valve of a pulsed backflush system consists of a membrane, a nozzle, a spring, a valve cover, and an air distributor. The nozzle is located inside the purge air box and its top serves as a valve seat. With the valve closed, the membrane is tightly pressed against the nozzle by the spring and the pressure of the air below the membrane, where it enters through three small holes on the periphery of the membrane. On the valve cover, a metal pressure housing-frame is installed, which ensures a tight fit of the membrane to the surface of the box. The upper opening of the valve cover is tightly closed by the air distributor. The operation of the membrane valves is controlled by an electronic device that delivers a control electric pulse in accordance with a predetermined program alternately for each valve with an adjustable pause between pulses. At the same time, either one sleeve (16-, 24-bag filters), or two sleeves (36-, 48-bag filters), or three sleeves (72-bag filter) are blown.

According to RF patent No. 2137530 for invention (3), patent holder Japan Newclear Cycle Development Institute (JP), the inner space of the dust collector is divided into upper and lower cavities by a baffle element equipped with several cylindrical filters. The suction channel communicates with the lower cavity for dusty gas, and the common outlet channel communicates with the upper cavity for purified gas. The exhaust duct of the dust collector is connected to an exhaust fan. A chamber for extracting collected dust is mounted on the lower conical end of the dust collector body. The dust collector is equipped with back-purge shut-off valves capable of opening and closing the upper end parts of the cylindrical filters and having back-purge nozzles, shut-off valve actuation mechanisms for opening and closing shut-off valves, compressed air hoses connected to shut-off valve back-purge nozzles, and reverse purge solenoid valves to control the supply and shut-off of compressed air used for reverse purge to compressed hoses wow air. Due to this design, the cylindrical filters can be backwashed independently, by supplying compressed air to the filters through the compressed air hoses, with the upper end parts of the cylindrical filters closed by shut-off valves. Filters can be purged sequentially one after another, and all filters can be purged at once backward.

Also known is a filter for dust collection of the Swiss company BULLER AG according to the patent of the Russian Federation No. 2189272 for the invention (4), which is taken as a prototype. According to the technical solution protected by this patent, a bag filter for dust removal of air consists of a housing with a lid, an inlet for raw gas and an outlet for purified gas. The cavity for the raw gas is separated from the cavity for the purified gas by an intermediate bottom on which filter bags are fixed. In the lower part of the cavity for raw gas under the filter sleeves there is a cone-collector for collecting settled dust and a sluice gate for unloading it from the filter. The sleeves are mounted in the vertical direction and loaded with dusty air from the outside, and the cleaned air flows out through the filter sleeve in the axial direction into the cavity for purified air, and from there into the outlet for purified gas. To clean the filter bags through a purge air nozzle, a set of intervals or after the pressure difference is established in the direction opposite to the normal direction of flow, compressed air is blown in the form of a short and powerful pulse. The purge air nozzle is driven by a magnetic valve, and each sleeve has its own nozzle and its own purge air control valve. The existing electronic control circuitry with which the solenoid valves are connected ensures that different purge cycles are observed. Obtaining compressed air is carried out through a common pressure cavity, which is located above the cavity for purified gas and is formed by the housing cover and the bottom, which restricts the cavity for purified gas from above. The pressure cavity is constantly under blast pressure equal to about 0.5 bar.

The technical task of the invention is to increase the filter performance and reduce the cost of the design, providing a purge of the filter bags.

According to the proposed technical solution, the filter contains a housing with a lid, inlet and outlet nozzles of the cleaned air, filtering sleeves, a system for backflushing the filtering sleeves and a device for unloading trapped dust. The filter housing is divided into a chamber for dusty and a chamber for purified air. Venturi tubes are installed in the chamber for purified air at the intermediate partition. A filter sleeve is attached to the lower end of each venturi. On the purified air chamber, a partition is installed on top to which a cover is attached. A closed pressure cavity for compressed purge air, which is constantly under pressure of purge air, forms between the tightly connected lid and the baffle.

The task of increasing the filter performance and reducing costs for the design that provides purging of the sleeves, is solved by placing valves that regulate the flow of air to the purge directly in the pressure cavity. This allows you to abandon special nozzles that allow a pulse of compressed air from the pressure cavity to the filter sleeve, from structures for attaching nozzles and valves in the cleaned air chamber, reduce the number of valves due to the possibility of simultaneously purging several filter bags with one valve, without compromising purge quality. Such a purge of the filter bags is achieved by applying a distribution cavity and creating a double pulse of purge air in it from one valve to simultaneously purge several filter bags. From the total volume of the pressure cavity, air is supplied to a normally closed solenoid or pneumatic valve. Located above the valve membrane, air together with the spring exerts pressure on the valve membrane from above. At the moment the signal arrives at the valve control, the air outlet channel opens through the drain pipe into the distribution cavity and then through the nozzles into the cleaned air chamber, creating the first weaker impulse of purge air. This first impulse, leaving the distribution cavity into the purified air chamber, creates a vacuum in the distribution cavity due to the pressure differential between the pressure cavity and the purified air chamber. This contributes to an even distribution of the main impulse along the nozzles and filter bags. In the next instant, the valve membrane opens, passing air from the pressure cavity through the main passage into the distribution cavity, from which it enters the filter bags through the venturi pipes or directly without them, thereby creating a second main powerful impulse of air for purging. Both air pulses pass within a second. In the prototype, the air entering the valve cavity above the membrane is simply blown off through the silencer, without creating any beneficial effect.

Each distribution cavity is connected to several nozzles, each of which supplies purge air to one specific venturi and then to one specific filter sleeve. The distribution cavity can have a different configuration and can simultaneously serve up to ten filter bags. Thus, the purge of several filter bags is carried out by a double pulse of compressed air with a pressure of 0.5-0.8 atm within one second from one distribution cavity with one valve. The magnitude of the pulsed air flow necessary for a good purge of the hoses is achieved by the throughput of the aforementioned compressed air supply system and, if necessary, can be enhanced by the use of Venturi pipes with their known aerodynamic properties. Installation of valves in the pressure cavity allows the use of this filter at high temperatures of the cleaned air, for example in metallurgy. In addition, the absence of additional parts, the simplicity and rigidity of the purge system design provided by the welding of parts, increases the reliability of the proposed filter in comparison with the prototype.

The invention is illustrated by drawings.

Figure 1 - General view of the filter with a partial section of the chamber of purified air and the pressure cavity of the purge air.

Figure 2 is a schematic illustration of one of the options for supplying a pulse of compressed air from the distribution cavities for purging simultaneously in several filter bags.

Figure 3 - the principle of operation of the valve.

The bag filter has a housing 13, which is separated by an intermediate wall 11 with the purified air chamber 10. Dusty air enters the filter housing 13 tangentially through the inlet port of the cleaned air 12, twisting in a spiral. Heavy particles of dust under the influence of gravity settle in the discharge bottom, and light particles settle on the filter bags 1. The purified air through the filter sleeve 1 and the Venturi pipe 2 rises into the chamber of purified air 10 and is removed from the filter through the outlet pipe of the purified air 9. Venturi pipes 2 are mounted on the intermediate partition 11. At the lower end of the venturi 2, a filter sleeve 1 is attached using a clamp. The service of the sleeves 1 is through the doorway 5 in the filter housing. The sleeves 1 are cleaned of dust settled on them by reverse blowing with compressed air from the pressure cavity 15 formed by the lid 8 and the baffle 14. Compressed air enters the pressure cavity 15 through the nozzle 6. The pressure cavity 15 is constantly under pressure from the purge air. In the pressure cavity 15, the distribution cavities 16 are mounted on the partition 14, with the valves 4 installed on them. One valve 4 is installed on one distribution cavity 16. To supply compressed air from the distribution cavity 16, nozzles 7 are mounted on the partition 14 to connect the distribution cavity 16 to cleaned air chamber 10. The nozzles 7 are aligned with the venturi tubes 2 and with filter sleeves fixed to them 1. When the power is turned off, the solenoid 21, the pilot chamber 20 of the valve 4 is filled compressed air of the pressure cavity 15 through the valve inlet and the holes in the diaphragm 17. The stem 18 is pressed against the valve seat by the air pressure in the pilot chamber 20 and the force of the compressed spring 19, excluding the pressure cavity 15 from the distribution cavity 16 through the outlet 1. The electromagnet armature 21 is in the lowest position, also excluding the communication of the pilot chamber 20 with the distribution cavity 16 through the outlet 2 through the drainage tube 3. When power is applied to the electromagnet 21, the armature is retracted and frees air from the pilot chamber 20 to exit 2 and further through the drainage tube 3 to the distribution cavity 16. From the distribution cavity 16, an air pulse through the nozzles 7 goes to the venturi 2 and then to the purge into the filter bags 1. This forms the first pulse of purge air. In this case, a pressure drop occurs in the pilot chamber 20, due to which the force of the rod 18 against the seat decreases, becoming smaller than the upward pressure force of the air located in the valve cavity under the diaphragm 17. Therefore, the rod rises and frees air from the pressure cavity 15 through the valve inlet to the outlet 1 and further to the distribution cavity 16. From the distribution cavity 16, an air pulse through the nozzles 7 goes to the venturi 2 and then to the purge into the filter bags 1. This forms a second more powerful purge pulse air.

Short notation:

1 - filter sleeve

2 - venturi pipe

3 - drainage tube

4 - valve

5 - doorway for service sleeves

6 - fitting of compressed air

7 - pipe

8 - filter cover

9 - outlet pipe for purified air

10 - purified air chamber

11 - intermediate partition

12 - pipe inlet of cleaned air

13 - filter housing

14 - partition

15 - pressure cavity

16 - distribution cavity

17 - aperture with holes

18 - stock

19 - spring

20 - pilot camera

21 - electromagnet

Information sources

1. Voloshin N.P. and others. Reducing the energy intensity of mill pneumatic conveying installations. M .: Kolos, 1978, p. 104-106.

2. RF patent No. 2191061 for the invention of "Bag Filter", cl. B01D 46/02, claimed 23.04.2001, published 20.10.2002.

3. RF patent No. 2137530 for the invention of "Cyclone dust collector", cl. B01D 46/02, B04C 9/00, claimed 11.11.1997, published 09.20.1999.

4. RF patent No. 2189272 for the invention of "Filter for dust collection", cl. B01D 46/02, claimed 04/14/1998, published 09/20/2002.

Claims (2)

1. A filter for collecting dust, comprising a housing with a cover, nozzles for the inlet of the cleaned and the outlet of the cleaned gas, a dust discharge device, a pressure cavity that is located under the filter cover and is constantly under pressure of purge air, as well as filter bags installed in the filter housing, characterized in that it is provided with one distribution cavity or several distribution cavities with one control valve for each cavity, providing simultaneous purging of several filtering sleeves, while the distribution cavity and control valves are located in the pressure cavity of the filter. 2. The dust filter according to claim 1, characterized in that solenoid or pneumatic valves are used as control valves.

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