WO1982001665A1

WO1982001665A1 - Apparatus for the separation of solid particles mainly for applications requiring increased operational safety

Info

Publication number: WO1982001665A1
Application number: PCT/HU1981/000044
Authority: WO
Inventors: Gyogyszervegyeszeti Gyar Egypt; Tamas Zagon; Miklos Karpati; Istvan A Pattantyus; Jeno Szemmelroth
Original assignee: Egyt Gyogyszervegyeszeti Gyar
Current assignee: Egyt Gyogyszervegyeszeti Gyar
Priority date: 1980-11-11
Filing date: 1981-11-11
Publication date: 1982-05-27
Anticipated expiration: 1983-05-11
Also published as: ES8801989A1; BE891104A; DK283082A; SE8204159L; FR2493722A1; HU183245B; DD201855A5; JPS57501912A; PL233775A1; GB2099719A; SE8204159D0; AU8626382A; ES506971A0; NL8120441A

Abstract

Apparatus for the separation of solid particles, which by its structural design can be operated with high reliability its filtering capacity during operation can be followed with attention in a simple way and it can be used equally for the separation from liquids and gaseous medium, mainly in the fields requiring increased operational safety, thus for instance in the field of the pharmaceutical industry, organic chemical industry and even in the field of the nuclear industry, etc. The apparatus for the separation of solid particles according to the invention is suitable mainly for meeting the demands requiring increased operational safety, and it is formed with a primary space for receiving solid particles and medium, in given case for carrier medium and with a secondary space for the collection of filtered medium separated from each other by a filter member. In essence the filter member has a first filter element and a second filter element, the first filter element is arranged to confine the primary space, the second filter element is arranged to confine the secondary space, the first filter element is arranged to confine the primary space, the second filter element is arranged to confine the secondary space, the first and second filter elements together with the primary space only through the adjoining first filter element and with the secondary space only through the adjoining second filter element form an intercommunicating intermediate space, and an internal pressure sensor is arranged in the intermediate space.

Description

APPARATUS FOR THE SEPARATION OF SOLID PARTICLES MAINLY FOR APPLICATIONS REQUIRING INCREASED UPERATIONAL SAFETY

The invention belates to an apparatus for the separation of solid particles, which by its structural design can be operated with high reliability its filtering capacity during operation can be followed with attention in a simple way and it can be used equally for the separation from liquids and gaseous medium, mainly in the fields requiring increased operational safety, thus for instance in the field of the pharmaceutical industry, organic chemical industry and even in the field of the neuclrar industry, etc.

Filter apparatuses are generally used for the separation of solid particles, seberal varieties of which are known. Irrespective of the fact, that the product to be separated or purified is in solid, gaseous or liquid state, the general construction of the apparatuses is characterized by beingprovided with a primary space for the joint reception of medium and solid particles, with a secondary space for the collection of filtered or purified medium, and for the transfer therefrom and these two spaces are in intercommunication through a filter.

During operation of the apparatuses the solid particles while flowing through the filter fed in together with the medium, or those entrained by the flowing medium are separated from the medium fed into the primary space under pressure, they are deposited on the filter surface at the primary space side, and depending on their material they are accumulating in the lower half of the primary space, the medium flowing through the filter is collected in the secondary space, then passes out of the apparatus.

The solid particles retained on. the fiilter clog the apertures of the filter surface. Thus resistance of the filter unit against the flow increases with the progress of of the filtering process, the filtering capacity will decrease, and at the same time the pressure will fixe in the primary space. This pressure rise will increase the wear of the filter and the risk of breakdown, such as apertures larger than required in the material of the filter, and/or the danger of the filter material getting torn out of its setting.

Breakdown of the filter will entail stopping the operation of the apparatus, its cutout from the technological process, its disassembly to the necessary extent, detection and repair of the faulty filter, or replacement of the filter material, at the same time it entails shortfall in the production and/or loss of product during the time between the occurrence and detection of the fault and stopping the operation of the apparatus, thereby causing damage and/or pollution of the environment. In case of filter breakdown at intermittent production the filter may become polluted, which necessitates the repeated filtering of the charge.

In order to avoid such breakdown hazards and to keep the filtering capacity on the same level, clogging of the filter is prevented by eliminating the deposition of solids on the filter surface, or by loosening the layer of the deposited material and removing it from the filter surface, for which several solutions have been worked out. Mechanical devices are used in a major group of the solutions.

Such mechanical devices maybe fork-, or stripper ring-type loosening devices, or those with knife as recommended for gas filters in the Hungarian patent specification No. 171 278, which remove the separated material from the filter surface by movement of the applied strippers on the filter surface at the simultaneous deformation of of the filter in case of certain solutions.

Another group of the mechanical devices used mainly in case of bag, hose or pouch-type filters is represented by vibrators, such as used in the solution described in the GFR patent specification No. 1 607 722. The vibrators move the filter mainly in the direction of the longitudinal centreline and thereby the separated material is thrown off the filter surface.

Use of the mechanical devices has many disadvantages, Main disadvantage is the wear of the filter material, which reduces its life, and breakdown is more frequent. In addition when vibrators are used, the vibration is effective only on a certain part of the filter, the separated material is deposited in the vicinity of the filter setting, and they can be removed only after disassembly of the apparatus.

The mechanical devices are generally arranged in the primary space receiving the medium to be filtered, which entails increased wear and frequent breakdown and their repair can be generally carried out by disassembly of the apparatus. Further disadvantage is, that as mechanical devices they require constant maintenance and are relatively costly.

In a further group of the solutions, mainly in the group of the bag-type dust separators, as for instance in case of the solution described in the English patent specific ation No. 1 151 845, as well as in the GFR patent specification No. 1 757 515 the filter is cleaned with counterflow flushing, mostly during the filtering process with back-blow. The counterflowing pressurized medium, mostly gas loosens the deposited layer and it is thrown off by stretching the filter material.

At this kind of filter apparatuses the efficiency of counter-flushing is partly increased by controlling the frequency of counter-flushing, which is dependent on the clogged condition of the filter as for instance in the apparatuses described in the English patent specifications No. 1 290 786 and 1 350 145, and partly by the individual construction of one or more inlet throats reaching into the interior of the bag-type filter reserved for the counter-flushing medium, as described in the English patent specification No. 1 302 447 and GFR patent specification No. 1 751 926. At the same time the described solutions using counter-flow flushing have several disadvantages. The structural units bringing about the counterflow and the connected parts render the buildup of the apparatus very complicated and the maintenance and repair are considerably difficult. Further disadvantage is that variation of the stretching direction of the filter materials reduce the life of the mostly woven material, Increases the danger of breakdown and tear-out. In addition the price of such filter apparatuses and the additional costs of operation - with regard to the advantages as well - can be regarded as being disproportionate in relation to the simpler filter apparatuses.

Although the combined application of the various purifying solutions - such as flushing combined with vibration carried out with the device described In the GFR specification No. 1 752 515, or counterflow-flushing with simultaneous stretching carried out with the bag-type filters described in the Hungarian patent specification No. 169 389 - hinder the occurrence of clogging, but wear of the filter material is increased and thus its life is reduced. In certain, mainly in the nuclear industrial fields requring increased operational safety, the undesirable phenomena arising from filter breakdown are avoided by the use of refiltering devices, or cascade filters when filtering liquids containing radioactive material derived from uranium-enriching apparatuses, or liquids containing radioactive material derived from atomic power station. Although such solutions increase the operational safety, they are very costly, since two or more apparatuses essentially with identical parameters are required. Generally one of them is inactive in the production and at the same time in case of filter breakdown it is necessary to stop the operation of each apparatus for disassembly and cleaning.

Such silutions are also known, as for instance the one recommended in the English patent specification N o . 1 133 590, where the condition of the filter material is watched with particle sensor placed into the flow of the filtered medium, or the solution recommended in the English patent specification No. 1 281 588, where the leakageproof condition of the air filter insert is inferred from the differential pressures measured before and after, and the necessity of changing the filter insert arises upon reaching a given differential pressure. Common disadvantage of the described solutions is, that although they reduce the danger of clogging to a lesser or higher degree, they can not prevent breakdown of the filter material, on the contrary its danger is even increased by the use of certain solutions. Elimination of the filter clogging or breakdown requires cutout of the operation of the apparatus entailing loss in production, while during the interval between occurrence and detection of the fault and stopping the apparatus, loss of product may occur representing considerable financial value and/or environmental pollution, or the more costly refiltering of the filtrate may also become necessary. At the same time elimination of the fault necessitates finding the defective filter which generally requires long work, followed with repair of the apparatus.

Common deficiency of the known filter apparatuses is represented by the fact, that only limited information or none is obtained on the clogged condition of the filter members during operation.

The described disadvantages and deficiencies made it necessary to develop such apparatus for separation of the solid particles, which even in case of breakdown of the filter material will ensure continuity of the efficient operation of the apparatus without shortfall in production and/or loss of product, or without the demand for repeated filtering.

Realization of the apparatus was aimed at such construction as to establish the fact and location of the breakdown simultaneously with its occurrence without disassembly of the apparatus and without outside intervention.

Furthermore such construction of the apparatus was aimed at, which is capable to furnish continuous information on the leakageproof condition of the filters during operation, in order to keep the filtering capacity at a constant, favourable value, if necessary by change of operation, cleaning or maintenance.

The invention is based on the recognition, that the mentioned disadvantages and deficiencies can be eliminated by such construction of the apparatus, where the filter is individually formed suitably by a filter member assembled as a single unit, provided with a primary filter surface and with a safety secondary filter surface activating the primary filter surface in case of breakdown, and it is provided with a device furnishing continuous information on the filtering capacity of any filter surface of the filter member during operation.

The apparatus for the separation of solid particles according to the invention is suitable mainly for meeting the demands requiring increased operational safety, and it is formed with a primary space for receiving solid particles and medium, in given case for carrier medium and with a secondary space for the collection of filtered medium separated from each other by a filter member. In essence the filter member has a first filter element and a second filter element, the first filter element is arranged to confine the primary space, the second filter element is arranged to confine the secondary space, the first and second filter elements together with the primary space only through the adjoining first filter element and with the secondary space only through the adjoining second filter element form an intercommunicating intermediate space, and an internal pressure sensor is arranged in the intermediate space.

A preferable construction of the apparatus according to the invention has a first differential pressure gauge indicating the differential pressure in the primary space and intermediate space.

A further preferable construction of the appa- ratus according to the invention has a second differential pressure gauge indicating the differential pressure in the secondary space and intermediate space.

During operation of the apparatus according to the invention the solid particles are separated from the medium flowing through the filter member on the surface of the first filter element adjoining the primary space, as on the primary filter surface of the filter member. The solid particles clog the apertures of the filter, material, thus the permeability of the first filter member is reduced and thereby the differential pressure increases in inverse proportion in the primary space and intermediate s pace . This differential pressure is indicated by the first differential pressure gauge and it is in proportion with the permeability of the first filter element within certain limits. Permeability of the second filter element is practically constant, the pressure, which is the difference between the pressures in the intermediate space and secondary space, is constant only according to the quantity of medium flowing through. It is the first filter element that becomes decfective in the first place, in this case separation of the solid particles continues on the surface of the second filter element adjoining the intermediate space, as on the second filter surface of the filter member, thus the normal operation of the apparatus can be continuously maintained without any undesirable consequences. At the same time as a result of the defective first filter element, the pressure increases in the intermediate space, and it approaches or equals the pressure in the primary space. This is indicated by the first differrntial pressure gauge, and thereby breakdown of the first filter element can also be sensed.

Operation of the second filter element can be similaryl followed with attention by the pressure values indicated on the second differential pressure gauge.

The apparatus according to the invention may also be constructed in such a way, that within the housing of the apparatus several parallel operating filter members are arranged.

The filter members are arranged by fitting into openings formed on the wall between the primary and secondary spaces, by fastening on frame, or in any other conventional way. In accord with the invention it is suitable to arrange pressure sensors in the intermediate space within each filter member, the pressure data obtainable from the primary and secondary spaces will give separate information on the condition of the primary and secondary filter surfaces of each filter member.

The solution according to the invention is suitable for the construction of such apparatus, where within a filter member and in addition to the first filter element adjoining the primary space further filter element(s) is/are arranged dividing the intermediate space into two or more smaller closed s paces . This way the operational safety of the apparatus will be increased.

In respect of the invention the construction, shape and fastening method of the filter members are indifferent. Thus the solution of the filter elements is generally conventional, suitably formed as bag-, hose, or pouch, or stretched flat, mounted on frame, the filter fabric of natural, synthetic, possibly of metal, textile material, etc. pulled over an insert, with a build-up most suitable to the demands and purposes, with the use of spacer and fixing method.

The filter member may be mounted as a single unit, but its filter members are separately replaceable.

Such filter members may be used to advantage, where the first filter element and/or the second filter element is bag, hose or pouch. In a preferable construction of the invention the bag, hose or pouch-type first filter element and the same shaped second filter element are arranged opposite each other, opening into each other and are connected to each other along the edges of their openings by sealing off the intermediate space.

In another preferable construction of the apparatus a bag, hose or pouch-shaped filter element of the filter member is reaching into the interior, while - opening in the same direction - another smaller filter element of similar shape is arranged and they are connected to each other along the dge of their openings by sealing off the intermediate space.

In a further preferable construction of the apparatus opposite the opening of the bag, hose or pouch-shaped filter element of the filter member another flat filter is arranged covering the former one , and the two filter elements are connected to each other by sealing off the intermediate space. The type and system of the pressure sensor arranged in the intermediate space are determined by the application conditions and safety technical specifications. Mostly pneumatic sensors, U-tube pressure gauges, hydraulic pressure sensors, or their alternatives combined with electronic sign converters are applicable. The differential pressure sensors and gauges conform to the type and system of the sensors.

The apparatus according to the invention may be used as an independent filter apparatus for individual applications, or it may be associated with devices of other functions, such as built together with drier, for the separation from pneumatic medium it may serve as fluidization drier, or built together with cyclone as filter cyclone, etc., and in case of separation from liquid medium it may be complemented with devices suitable for carrying out chemical industrial operations requiring simultaneous filtering.

The main advantage of the apparatus according to the invention is, that it gives continuous information on the condition of its filter surface and thus on the momentary filtering capacity during operation of the apparatus. Should any of its falter elements break down, the fact of breakdown will be instantly indicated and at the same time on the basis of the received informations the defective filter element can be identified without disassembly of the apparatus, which makes it much easier, especially in case of several filter members and/or at multi-functional apparatus.

The possibility of breakdown exists mainly in the first filter element, which in the construction according to the invention has no direct effect on the operation of the apparatus. Function of the first filter element, i.e. the separation is taken over simultaneously with the breakdown by the second filter element, thus continuity of the operation of the apparatus can be maintained. This gives the possibility for carrying out the elimination of the fault in a technologically more opportune point of time.

Further advantage against the conventional apparatuses of such purpose is, that upon breakdown of the first filter element separation of the solid particles continues in the intermediate or primary space, and the solid particles do not enter the secondary space, thus loss of product involving financial consequence or environmental poluution and/or shortfall in the production, or repeated pollution of the already purified gas, or liquid do not arise. This makes the use of various control instruments unnecessary especially in case of process control with instrument. The apparatus can be favourably fitted into automatic process controlled systems.

Essence of the invention is described in detail by way of example with the aid of the enclosed diagrams, in which: Figure 1.: Block diagram showing the cross section of a fluidization drier. Figure 2. a.: Cross section of a possible alternative of the filter member arranged in a fluidization drier. Figure 2.b.: Cross section of another possible contruction of the filter member arranged in a fluidization drier. The main parts of the fluidization drier 10 shown in Figure 1 are house 13,15, orifices 17, and filter member 12. The filter member 12 is fixed to flange or partition wall in the interior of house 11, and it divides the interior of house 11 primary - powdery substance - space 14 and secondary purified medium - space 16. Inlet opening. 13 and charging orifice 17 are leading into the secondary space 16.

Filter member 12 has bag, hose or pouchshaped first filter element 21 and the same shaped secind filter element 22, which together form the intermediate space 18. The intermediate space 18 is separated from the primary space by the second filter element 22 and communication with the intermediate space 18 is possible only through the corresponding adjoining filter element, and communication between the primary space 14 and secondary space 16 is possible only through the intermediate space 18. The first filter element 21 and second filter element 22 are arranged opposite each other, leading into each other, and are interconnected along the edge of their openings by sealing off the intermediate space 18.

Drier mixer 50 is built into the primary space of housing 11 of the fluidization drier 10.

First pressure sensor 31 is arranged in the primary space 14, second pressure sensor 32 in the secondary space 16, while the internal pressure sensor 30 is arranged In the intermediate space 18. The first pressure sensor 31 with the first outlet of the intermediate pressure sensor 30 is connected to the first differential pressure gauge 41, while the second pressure sensor 32 with the second outlet of the intermediate pressure sensor 30 is connected to the second differential pressure gauge 42.

During operation of the fluidization drier 10 the wet powdery substance to be dried is admitted through the charging orifice 17, while the pressurized drying pneumatic medium is admitted through the inlet opening 13 into the primary - powdery substance - space 14. The flowing pneumaticmedium dries the wet powdery substance by floating in the primary space 14. The solid particles entrained by the pneumatic medium flowing from the primary space 14 through filter member 12 are separated on the outer surface of the adjoining first filter element 21 as on the primary filter surface of the filter member 12 and are accumulating partly on this filter surface, and partly falling off into the lower space of the housing 11.

The medium flowing through the first filter element 21 passes into the intermediate space 18, therefrom through the second filter element 22 into the secondary - purified medium - space 16, leaving it through the outlet opening 15.

Drying of the solid particles filtered from the medium and accumulating in the lower space of housing 11 is facilitated by the mixer 50 arranged therein.

During normal operat i on of the fluidization drier 10 the pressure in the primary space 14 is greater than that in the intermediate space 18.

Thε differential pressure Δ p_a of these two pressures can be sensed and measured with the first differential pressure gauge 41.

The differential pressure Δ p_b i.e. the pressure between the intermediate space 18 and secondary space 16 depends mainly on the quantity of medium passing through the second filter element 22 during the unit of time, aid can be sensed and measured with the second differential pressure gauge 42.

During the progress of the drying process - as a result of the solid particles accumulating on the filter surface of the first filter element 21 as on the primary filter surface - the differential Δ p_a shows increasing, and the differential pressure Δ p_b decreasing tendency. In case of breakflown of the first filter element 21 the solid particles are separated also on the surface of tee second filter element 22 at the intermediate space 18 side, as on the secondary filter surface of filter member 12. Thus continuity. of the filtering is maintained and the normal operation of the apparatus remains constant.

In case of breakdown of the first filter element 21 the pressure condition will change, value of the differential pressure Δ p_a drops, in extreme position it becomes 0, while the value of the differential pressure Δ p_b will rise.

Watching the variation of the differential pressure value Δ p_a with the simultaneous watching of the differential pressure value Δ p_b as necessary makes it possible to sense the clogging and/or breakdown of the first filter element 21 during operation. Repair or replacement of the defective filter element at a technologically opportune time ensures the continuity of the operation of the apparatus.

In case of several parallel operating apparatuses, or filter members the filtering capacity of each first filter element 21 can be directly sensed by comparison of the differential pressure valus Δ p_a.

The indicator system for watching the differential pressure values Δ p_a simplifies and lowers the cost of automated instrument-controlled technological process.

Figure 2 illustrates some of the possible preferable constructions of the filter members applicable In the apparatus.

The alternative shown in Figure 2. a. in one of the bag, hose or pouch-shaped filter elements 23 of filter member 12 another smaller filter element 24 of similar shape opening in the same direction is arranged. The intermediate space 18 is confined by the filter element surfaces looking towards each other, i.e. by the inner surface of the of the outer filter element 23 and the outer surface, of the other inner filter surface 24. The filter elements are interconnected along the e dge of their openings by sealing off the intermediate space 18. The primary and secondary filter surfaces of the filter member 12 are determined by the existing flow direction during operation.

The filter elements can be fixed separately on suitable supporting structures, or into filter member holding fixture 25 mounted as a single unit as shown in the diagram, or in given case they can be fixed to each other with the use of suitable fixtures and only one of them or the fixture to suitable holder. This fixing is solved in such a way, that any of the filter elements and even the filter member 12 are replaceable in a simple way.

Selection of the filter elements for bagshape is advantageous, since when arranged in a space of specific extent, they offer greater filter surface in comparison with a filter element having different shape.

In the alternative shown in Figure 2.b. opposite one of the bag, hose or pouch-shaped filter elements 23 another flat filter element 27 is arranged covering the former one. The intermediate space 18 is practically the interior of one of the filter elements 23, limited by the surface of the flat filter element 27 facing the former filter element. The two filter elements are connected to each other by sealing off the intermediate space 18. The primary and secondary filter surfaces of filter member 12 are determined by the existing flow direction during operation.

The filter elements can be fixed separately to suitable holders, or fixed to holding fixture 28 mounted as a single unit as shown in Figure 2.b., or the filter elements can be fixed to each other with the use of fixture or fastening device as necessary, and by fastening one of them to flange, or partition wall.

Claims

Wha t we cla im is

1. Apparatus for the separation of solid particles, mainly for useage requiring increased operational safety, formed with primary space for receiving solid particles and medium, in given case carrier medium, and with secondary space for receivirgfiltered medium, said spaces are separated from each other by filter member, characterized in that the filter member /12/ has a first filter element /21/ and a second filter element /22/, the first filter element /21/ is arranged to confine the primary space /14/, the second filter element /22/ is arranged to confine the secondary space /16/, the first filter element /21/ and second filter element

/22/ together form an intercommunicating intermediate space /18/ with the primary space /14/ only through the adjoining first filter element /21/ and with the secondary space /16/ only through the adjoining second filter element /22/, furthermore an internal, pressure sensor /30/ is arranged in the intermediate space /18/.

2. Apparatus as claimed in claim 1., characterized in that it has a first differential pressure gauge /41/ sensing the difference between the pressures in the primary space /14/ and intermediate space /18/.

3. Apparatus as claimed in claim 1 or 2., characterized in that it has a second differential pressure gauge /42/ sensing the difference between the pressures in the secondary space /16/ and intermediate space /18/. b. Apparatus as claimed in any of claims 1 - 3., characterized in that the first filter element /21/ and/or the second filter element /22/ of the filter member /12/ are formed as bag, hose, or pouch.

5. Apparatus as claimed in claim 4., characterized in that the filter member /12/ has a bag, hose or pouch-shaped first filter element /21/ and same-shaped second filter element /22/ arranged opposite each other and opening into each other, and are interconnected along the edge of their openings by sealing off the intermediate space /18/.

6. Apparatus as claimed in claim 4., characterized in that a bag, hose or pouch-shaped filter element /23/ of the filter member /12/ is reaching into the interior, while opening in the same direction another smaller filter element /24/ of similar shape is arranged, and they are connected to each other along the edge of their openings by sealing off the intermediate space /18/.

7. Apparatus as claimed in claim 4., characterized in that opposite the opening of one of the bag, hose or pouch-shaped filter elements /23/ of the filter member /12/ another flat filter element /27/ is arranged covering the former one, and the two filter elements /23, 27/ are connected to each other by sealing off the intermediate space /18/.