RU2432982C1 - Bag filter filtration element - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to gas filtration. Proposed filtration element comprises main hollow block of porous ceramics with exposed pores. Additional hollow block, its length making 0.1-0.2 of that of the main block and inner diameter making 0.7-0.9 of its inner diameter, fits tightly in inlet end of the main block for 50%. Said additional hollow block features shape of the main block.

EFFECT: higher filter dust retentivity, reduced drag in high-temperature gas filtration.

1 dwg, 3 tbl

Description

The invention relates to the field of filtering devices, in particular, to the design of filtering elements of a bag filter, and can be used in filtration plants for filtering hot (500-1200 ° C) gases from high-temperature process units in ferrous and non-ferrous metallurgy.

Currently, bag filters equipped with constant section fabric sleeves are used for dust collection in many industries. The type of fabric determines the performance of the filter unit.

Hose regeneration (dust removal) is performed by a pulse of compressed air or low-pressure reverse blowing. A dust deposit formed on the sleeves is removed to the hopper.

The main condition for the effective operation of dry gas cleaners is the right choice of filter cloth. Filter bags for gas purification in the ferroalloy industry are made of organic synthetic fibers or fiberglass.

Regardless of the fiber used, filter materials are divided into woven and non-woven (such as felt). In the production of woven materials, the thread is interwoven on looms. Nonwovens are made from synthetic and glass fibers. The structure of nonwovens is similar to felt. The simplest non-woven material used to manufacture filters is needle-like felt. “Needle-punched” fabrics, in comparison with woven fabrics, are cheaper, have better dust collection characteristics. However, their durability is lower than that of woven materials.

Abroad, hoses made of fiberglass are used to clean gases emanating from ferroalloy furnaces. Sleeve working temperature no more than 200 ° С. The tensile strength of glass fabrics is high, but very low resistance to friction and bending. When using fiberglass, a special sleeve suspension design is required - on adjustable springs. Regeneration of fiberglass hoses is allowed only with reverse blowing.

A special position is occupied by filter bags made of fabric made using membrane technology. The greatest experience in the manufacture of membrane-coated fabrics is possessed by American companies producing fabrics under the name "GORE-TEX" and "VNA-TECH". Elkem company sews sleeves from the GORE-TECH fabric and equips them with its gas scrubbers.

The membrane is a microporous PTFE membrane with a thickness of about 50 microns, which is attached to the surface of conventional filter materials, including felt and woven materials.

The disadvantage of sleeves with a membrane coating is their high cost. The operation of the sleeves with a membrane coating should provide for thorough preparation of gas for cleaning, excluding hit on the membrane surface of hot particles of coke, wood chips, coal. This limits their use in metallurgical units.

An important characteristic of the filter is air permeability, which determines the throughput of the filter unit, its dimensions and the effectiveness of gas cleaning from dust. The breathability of the filters is determined by the formula:

S = ΔP / V,

where S is a conditional indicator of breathability;

ΔP is the pressure drop across the bag filter, mm water column;

V is the gas velocity through the filter, m / h.

The conditional air permeability index for filters made from mylar fabric is 6, from fiberglass with a membrane coating of the GORE-TEX type - 4, from fiberglass - 8. The lower the value of the conditional air permeability index, the better the filter.

On dry gas purifications of Kuznetsk Ferroalloys OJSC, the gas-air mixture is diluted with air to a temperature of 150 ° C and cleaned of dust in pressure head filters. Gas, cleaned from dust, is emitted into the atmosphere through an aeration lamp.

Thus, the filter element of the bag filter, which is made of fabric in the form of a sleeve of constant cross section, is known from the prior art.

The disadvantage of industrial filtering elements (sleeves) of constant cross section is the low operational stability and efficiency, since the fabric, due to frequent deformation of the sleeves from direct for cleaning and reverse gas movement for regeneration, wears out quickly and fails. The wear of the filter element (sleeve) contributes to the low resistance of the fabric when cleaning gas with a high (more than 500 ° C) temperature.

Analogs and Prototypes

Known filter elements - sleeves of constant cross section.

Use sleeves made of a multifilament yarn consisting of elementary yarns of the same size arranged in parallel [1].

Sleeves made of thin metal or artificial threads are used. The size of the cells between the threads is reduced by coating the outer surface of the threads with an electrolytic method or by spraying [2].

Sleeves are made of fibrous canvas. The resulting non-woven material is superimposed on the thermoplastic non-woven material and both layers are punctured again. Then the two-layer nonwoven material is subjected to heat treatment, and the thermoplastic layer is melted, forming a porous structure for filtering [3].

Use filters from a material in which a continuous density gradient exists between the input and output sides in the layer with a uniform distribution of fibers in the cross section [4].

Filter bags of constant cross section are made on the basis of composite materials [5].

A disadvantage of the known constructions of filter elements (analogues) of constant cross section is the reduced filter retention ability when filtering high-temperature gas with dispersed sublimates of volatile compounds and the reduced operational stability of the filter element of the bag filter due to clogging of pores by dispersed dust.

In technical essence, the closest to the proposed filter element of the bag filter is the filter element of the bag filter made of cotton cellulose and powder sorbent [6].

A disadvantage of the known filter element of constant cross section is that when filtering gas with condensed dispersed sublimates of volatile compounds, the filter's filter retention capacity (filter efficiency by dust) is reduced due to deep clogging of pores. This increases the hydraulic resistance of the filter. The fabric of the bag filter due to frequent deformation from direct and reverse gas movement during regeneration and low temperature resistance wears out quickly and loses its filtering ability.

Description of the invention

The objective of the invention. Increasing the retention ability with respect to dust and reducing the hydraulic resistance of the filter when filtering high-temperature (500-1200 ° C) gas with dispersed sublimates of volatile compounds.

The problem is solved in that in the main block of the filtering element of the bag-type ceramic filter, an additional hollow block 0.1-0.2 times the length of the main block with an inner diameter equal to 0.7-0.9 of the inner diameter of the main block .

The essence of the invention lies in the fact that the proposed device increases the delay ability with respect to dispersed sublimates of volatile compounds, increases the filter resistance and reduces the hydraulic resistance of the filter when filtering high-temperature (500-1200 ° C) gas.

The drawing shows the proposed filter element of the bag filter.

The device contains a hollow block 1, which is made of porous ceramic with an inner diameter D. In addition, the device contains a block 2, which is made of porous ceramic with an inner diameter d and an outer diameter equal to the inner diameter (D) of block 1.

The connection of the hollow block 1 with the hollow block 2 is made by a hermetic connection and a circular sealing gasket 3, including a bolt tie. The ratio of the length of the block 2 to the length of the block 1 is 0.1-0.2. Block 2 from the inlet end along the gas movement enters 50% into the cavity of the hollow block 1. The protruding part of block 2 serves as a pipe for gas supply and attaching the subsequent filtering element of the bag-shaped ceramic filter. Moreover, from 2-10 tubular filtering elements form a sleeve of the estimated length.

A design feature is that the ratio of the inner diameter d of the hollow block 2 to the inner diameter D of the hollow block 1 is 0.8-0.9.

If the ratio of the inner diameter d of the hollow block 2 to the inner diameter D of the hollow block 1 is less than 0.8, then the filter capacity is reduced due to clogging of the filter material with dispersed dust particles.

If the ratio of the inner diameter d of the hollow block 2 to the inner diameter D of the hollow block 1 is more than 0.9, then the dust collecting capacity of the filter is reduced.

If the ratio of the length of the block 2 to the length of the block 1 is less than 0.1, then the effect of coagulation of dispersed sublimates and the trapping ability of the filter by dust are reduced.

If the ratio of the length of the block 2 to the length of the block 1 is more than 0.2, the filtering surface and the dust collecting capacity of the filter are reduced.

The principle of action is as follows. In the process of gas flowing from block 2 to block 1, gas oscillations are excited. Dust particles having a supply of kinetic energy, falling into the field of action of the field, which is a combination of zones of compression and rarefaction of the gas stream, lose it as a result of braking and coagulate. Under the action of a gas stream passing through the filter, particles fall on the filtering surface of block 1. This is facilitated by a decrease in the gas velocity in the volume of this block.

The location of the internal element (block 2) changes the speed and shape of the gas movement, intensifies the gas filtration process due to enlargement (coagulation) of particles of dispersed sublimates of volatile compounds. When this occurs, a uniform distribution of aggregated dust on the filtering surface of the unit 1.

As a result, the delaying ability with respect to dust is increased and the deep penetration of dust particles into the open pores of the filter is prevented, the filter resistance increases and the hydraulic resistance of the filter decreases when filtering high-temperature gas with dispersed particles of sublimates of volatile compounds.

The tight connection of the ceramic block 2 with a controlled sealing circular screed 3 increases the connection with the ceramic block 1. The controlled sealing screed (3) prevents gas leakage and pressure reduction during the blowing off of dusty sediment during regeneration of the filter surface.

The sleeve of the ceramic filter is drawn from 2-10 filtering elements using the output part of the unit 2. The assembled sleeve of variable cross section is mounted on the filter unit. A plug is installed at the end of the last filter element to prevent the release of untreated gas into the atmosphere.

In the process, a solid dust deposit is formed on the filtering surface of the hollow block 1 and block 2, which is removed into the hopper of the filter unit by backflushing. The filter element cleaned from dust sediment is operable in subsequent cycles.

As a result of repeated cyclic use of the filter element as part of the bag filter, no residual dust deposit forms on the filter surface of the hollow ceramic blocks.

During regeneration by reverse blowing, the inner element 2 serves as a stiffener, increasing the strength of the structure as a whole.

After regeneration, the filtering ceramic filter element is used in subsequent multiple cyclic operating conditions as part of a bag filter without mechanical wear.

The implementation of the filter element of the bag filter

The implementation of the filter element of the bag filter was performed on the industrial site of CJSC Synthesis-Plus.

A filter element of a bag filter of variable cross section was manufactured at the site. For the formation of blocks 1 and 2, porous ceramics obtained by pressing mullite-siliceous felt of the MKRV-200 grade, corresponding to GOST 23619-79 “Materials and products of refractory heat-insulating mullite-siliceous fiberglass”, was used. The product was impregnated with a liquid mineral binder (liquid glass). To impart through porosity, the product was purged with air, and sintered to impart strength. For tight connection of the ceramic block, a bolt-tight sealing circular coupler made of metal was used. The aspect ratio of the filter element of the bag filter is given in table 1.

Table 1 Aspect Ratio of the Filter Element of the Bag Filter Indicator Designation Minimum Average Maximum Main unit mm mm mm Length L 1000 1500 2000 Outer diameter DH_ocн 150 150 150 Diameter inside D 140 134 130 Wall thickness N_osn 10 16 twenty Additional unit Length I 200 200 200 Outer diameter dH_add 140 134 130 Diameter inside d 126 107.5 91 Wall thickness h_dop fourteen 26.5 39 Block size ratio Length ratio I / L 0.2 0.13 0.1 Diameter ratio d / d 0.9 0.8 0.7

The main unit of the filter element of the bag filter adopted for manufacture is a hollow cylinder with an outer diameter of 150 mm, a length of 1500 mm and a wall thickness of 16 mm.

An additional hollow block made with a profile of the main block 0.1-0.2 of the length of the main block and with an inner diameter equal to 0.7-0.9 of the inner diameter of the main block.

To give increased mechanical strength and tightness at the junction of the blocks on the outer surface of the main unit, a bolt-tight sealant is installed.

The filter element of the bag filter adopted for manufacture complies with the standards given in table 2.

table 2 The performance of the filter element bag filter adopted for the manufacture Name of indicator Norm Breaking strength not less than, kg / cm ² 1,5 Breathability of the filter not less than m ³ / m ² per min 2 Crack resistance when heated to 500 ° C and cooled to 20 ° C at a rate of 30 ° C per minute, heat exchange, not less one hundred

Table 3 shows the test results of the filter element (prototype) and the proposed technical solution.

Table 3 The test results of the filter element (prototype) and the proposed technical solution Indicator unit of measurement Prototype The ratio of the diameters between the walls inside the blocks (d / D) 0.7 0.8 0.9 Holding Power (COP) % 80 95 98 96 Filter durability (service life) Month one 5 10 8 Filter hydraulic resistance mm water column one hundred 60 55 70

Thus, the proposed filter element of the bag filter has an increased retention capacity in relation to dust by 15-18%, increased filter resistance (service life) by 5-10 times, a decrease in the hydraulic resistance of the filter when filtering high-temperature gas in 30-45 mm of water. Art.

Comparative tests have shown that the use of the proposed filter element of the bag filter in comparison with the known filter element of the bag filter increases the productivity of the installation by 2-2.5 times.

The tests performed show the possibility of widespread use of the ceramic filter element of the bag filter in industrial plants.

Thus, in the proposed technical solution, the delivered technical result is achieved.

Information sources:

1. Bratukhin A.V., Kostylev A.E. A method of obtaining a filter element. A.S. 1018691 USSR, IPC B01D 39/16. VNII synthetic. fibers. N 3369063 / 22-26; declared 12/23/81; publ. in BI, N19, 1983.

2. A method of manufacturing filters. Verfahren zur Herstellung eines Filters mit Poren von vorbestimmter und etwa gleicher MikrogroSSe sowie nach diesem Verfahren hergestelltes Filter Application 3515025 Germany, IPC B01D 39/14, G01N 33/12. Altenburger Electronic GmbH. N P3515025.4; declared 04/25/85; publ. 10/30/86.

3. Bartek Pavol Zilincik Miroslav, Mulik Milan, Sestak Jozef. A method of obtaining filter non-woven materials. Filtracna textilia: 8.4.28.1.7. Pat. 275988 CSFR, IPC 5 D01D 39/16. Vysumny Ustav Textilnej Chemie, Zilina. N, 1770-89; declared 03/22/89; publ. 01/22/92.

4. Tani Yatsuhiro, Ohmori Susumu, Komagata Hidaki. Filter material. Filter and process for the production thereof: 8.4.26.1. Pat. 4983193 USA, IPC 5 B01D 46/00. Toyo Koseki K.K., Nippondenso Co., Ltd. N 4,53220; declared 12/21/89; publ. 01/08/91; prior. 12.11.80, N 55-159959 (Japan); NPK 55/487.

5. Vasyukov V.I. A method of manufacturing a filter material. Pat. 2176697 Russia, IPC 7 D21F 11/14, B01D 39/18. Volzhsk OJSC Research institute of cellulose-boom. industry ". N, 2000119646/12; declared 07/21/2000; publ. 12/10/2001. Rus

6. Kanarsky A.B., Platitsina N.V., Ter-Oganesyan G.Sh. A method of manufacturing a filter material based on cotton cellulose and a powdered sorbent. Pat. RU No. 2081231, IPC D21H 27/08.

Claims (1)

The filter element of the bag filter containing the main hollow block of porous ceramic with open pores, characterized in that from the input end of the main hollow block hermetically enters 50% additional hollow block made with the profile of the main block, 0.1-0.2 in length the length of the main unit and with an inner diameter equal to 0.7-0.9 of the inner diameter of the main unit.

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