GB2119675A

GB2119675A - Filters

Info

Publication number: GB2119675A
Application number: GB08309289A
Authority: GB
Inventors: Adolf Margraf
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-05-06
Filing date: 1983-04-06
Publication date: 1983-11-23
Also published as: DE3246183A1; AU1387283A; GB2119675B

Abstract

In a gas filter with loose filtering material (1) forming slopes (8) on supporting surfaces (7), the supporting surfaces (7) are connected via a linkage (9) to an oscillatory device (10) so that they can be oscillated or tilted periodically to discharge used filter material and form new slopes. The gas passes from inflow (5) to outflow chamber (11). Discharged filter material is removed by worm (19), and recycled if dust is being removed, or disposed of if the filter particles absorb noxious gases. In the embodiment of Fig. 4, the whole filter unit is shaken to remove used filter material. <IMAGE>

Description

SPECIFICATION Filters The present invention relates to filters of the kind comprising a layer of loose fitting material in which a crude gas containing dust and/or noxious substances flows into said layer at one delimiting side of an upright layer of loose material containing loose or bulk material replenishable from a stock, via uncovered loose material facings or slopes formed within a housing on mutually parallel horizontal or almost horizontal supporting surfaces, and emerges at the opposed outflow side retaining the loose material, as purified gas.

Filters comprising a layer of loose material of the kind referred to above are frequently applied nowadays for purification of fumes, which are advantageous because of their high thermal loading capacity and advantageous operating costs. In these filters, the top layer of the loose material facings or slopes is affected in particularly high degree by the dust from the crude gas and for prevention of finally resulting high throughflow resistances, the procedure adopted in consequence consists in periodically renewing these facings or slopes by topping up or replenishment of the loose material by trickling.To accomplish this purpose, the procedure applied for example in the case of circular positioning of the loose material layers according to the German Offenlegungschrift No. 26 16 250 consisted in that the slopes of th#e loose material charged with dust particles are cut away by revolving clearing tools, so that new facings or slopes are formed by trickling replenishment of the loose material whereby the throughflow resistance is reduced again. The loose material facings or slopes were also removed by clearing tools even in the case of loose material in stepped form (see German Patent Specification No. 41 80 08). To remove the facings or slopes of loose material charged with dust, it has already been proposed moreover that the angle of slope be varied periodically by reciprocating horizontal displacements of the surfaces supporting said facings or slopes.All these proposals require considerable amounts of plant and equipment at high investment costs.

It is an object of the invention to effect the renewal of the loose material facings or slopes charged with dust and/or noxious substances after a particular period of crude gas throughflow in a particularly simple manner with comparatively small complexity of machinery and equipment.

In accordance with the invention, this and other objects is achieved by the provision of a filter housing having a crude gas infeed, advantageously situated at the bottom, the delimiting surface of the loose material layer being formed by unconfined loose material facings or slopes which rest on supporting surfaces mounted in the housing and which supports may periodically be set in oscillation or settable into intermittently oscillatory or tipping motion in direct or indirect manner.

Due to the supporting surfaces which may be set in oscillation periodically in direct or indirect manner an outflow or removal is secured in simple manner of the loose material facings which are renewed by trickling replenishment of loose material from the loose material layer remaining to be replenished, so that these may again filter dust out of the crude gas or are thereby enabled under appropriate selection of the nature of the loose material to fix noxious substances such as fluorine, hydrofluoric acid, sulphur, sulphur oxides or the like, so that the relatively pure gas issuing therefrom may be allowed to flow out into the environment without hindrance.

Advantageously two layers of loose material comprising the inflow and outflow surfaces delimiting the layers are positioned symmetrically with the outflow sides facing towards each other with mutual spacing, the said spacing forming a purified gas chamber closed off at one end side, connected to a purified gas duct at the other end side, covered at the top against trickling loose material and closed at the bottom, thereby substantially increasing the separation of particles and/or the fixing of noxious substances in the crude gas, and securing a higher volumetric efficiency within a filter housing and at the same time also allowing of application of conventional filter housings comprising a bottom collector space and a purified gas duct connected thereto.

It is particularly advantageous for the supporting surfaces of the loose material facings or slopes to be set in oscillation indirectly and intermittently, proceeding in such manner to this end that within a filter housing, one pair or several successive pairs, of separate symmetrically arranged layers of loose material are enflanked on all sides by a cage or housing, the walls of which comprise an interrupted floor having inwardly directed supporting surfaces with a top covering of the interruption, the two loose material facings of the inflow sides, a rear wall rearwardly delimiting the purified gas chamber and a front delimiting wall, which is in actual or approximate contact with the front wall of the housing, and its perforation and a perforation of the front housing wall connecting the purified gas chamber to the purified gas dust, whereas compartments supplied with the crude gas and connected to a bottom settling compartment are provided in Front of the inflow sides of the layers of loose material for the inflow of crude gas, and that the cage or housing of the layer of loose material is resiliently suspended and may be placed in oscillatory motion periodically by means of a vibrator or of another oscillation generator.

Due to this construction, a particularly uncomplicated structure of the loose material filter is obtained and, above all, and as compared to the embodiment embodying direct oscillatory drive to the supporting surfaces, almost total hermeticity is secured against loose material sliding after, and almost uniform after-sliding of the loose material is assured throughout the height of the loose material layers upon performing intermittent oscillation. This renders it possible moreover to separate each pair of loose material layers from the other pairs during periodical oscillation and thereby to block each pair consecutively against inflow of crude gas.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings, which show two embodiments in diagrammatic form by way of example, and in which:~ Figure 1 shows a first embodiment of filter plant, partially in vertical longitudinal crosssection through the dust gas space, of a filter housing, and partially in lateral elevation, Figure 2 shows a cross-section along line Il-Il of Figure 1, Figure 3 shows a partial horizontal crosssection along the line Ill-Ill of Figure 1, Figure 4 shows a longitudinal cross-sectional view of a second embodiment with pairs of layers of loose material enflanked in cage-like manner, Figure 6 shows a cross-section along line V-V of Figure 4, Figure 6 shows a partial cross-section along the line VI-VI of Figure 4, and Figure 7 shows the boxed part of Figure 4 marked X, with a modified embodiment of the crude gas inflow side.

Referring to the drawings, pairs of layers of loose material are arranged one after another in a filter housing 12. It is also possible however to provide only one layer of loose material in a housing, said layer having the features described in the following, the one lateral surface formed by loose material facings being connected to the crude gas supply and the opposed side being connected to a purified gas duct.

-According to Figures 1 to 3, each upright or vertical layer of loose material is delimited by perforated side-walls 2 and 3 and front and rear walls 1 2a, 13 of a housing, as well as by a floor 4.

A horizontal or approximately horizontal outwardly directed supporting surface 7 which are formed facings or slopes 8 of the loose material from the layer of loose material is situated in each case at the bottom edge of perforations of the wall 2 at the dust gas inflow side 5. The perforated wall opposed to the facings 8 consists, for example, of covering strips 3 sloping downwards towards the layer 1 arranged with mutual spacing in the manner of roof tiles and mutually parallel one above another. The perforated wall 2 may also be omitted, the gaps between the supporting surfaces 7 then having to be reduced.

The supporting surfaces 7 are mounted in articulated or flexible manner at their inner edge on the wall 2, and their outer edges are connected to an upwardly and outwardly guided linkage 9 acted upon by a vibrator 10, a crank drive or the like, which is placed in operation at intervals for renewal of the layers of the facings 8 charged with dust or fixed noxious substances, and thereby sets the supporting surfaces 7 into an oscillatory or downwardly tipping motion causing the loose material of the facings to trickle downwards over the outer edge or to be removed, and to drop downward into a collector compartment 18, as will be described further. Fresh loose material facings 8 are thereby formed from the loose material layer 1.

For improved spatial utilisation of a filter housing known per se, and to increase the filter performance, it is advantageous to combine two layers of loose material of the kind described, in mutually symmetrical position, and to house an optional number of such layer pairs 1 one behind another within a filter housing 12 as shown in Figures 1 to 3. Between the confronting covering strips 3, each pair of layers 1 then forms a purified gas chamber 1 1 which is covered at the top at 16 against replenishing loose material of the layers 1 in roof-like manner and is in communication with a purified gas duct 1 5 via a perforation of the front wall 13 of the housing.Crude gas is ducted to the layers 1 of loose material via spaces 14 and the facings 8, supplied from a crude gas feed 21 which advantageously opens into the bottom funnel-shaped collector compartment 18 comprising a conveyor screw 19 or the like, into which also drops the loose material from the facings 8 as soon as the supporting surfaces 7 are intermittently placed in oscillatory or tipping motion.

The loose material is fed to the layers 1 during the intermittent renewal of the facings 8 via a conveyor duct 17 and perforations of the housing cover 1 2b, from a stock, surplus loose material being downwardly ducted at the end of the conveyor duct 17 into the collector compartment 18 which also receives the loose material from the facings 8, from which it is conveyed to an outlet by the worm 19, in which connection it is possible to regenerate the loose material and to return the same to the conveyor duct 17 in a loop as shown in dashed lines.

It is advantageous to separate the pairs of layers 1 of loose material by means of transverse housing partitions 20 shown in dashed lines, thereby rendering it possible to renew the loose material facings 8 of the pairs consecutively by turning on the oscillatory drive, the appropriate pair of layers of loose material then being shut off from crude gas inflow, e.g. by interrupting the connection between the purified gas chamber 11 and the purified gas duct 15 by means of a slide 22 (Figure 3) which blocks the perforation in the front wall 13 of the housing.

Whereas according to Figures 1 to 3, the supporting surfaces 7 are placed in oscillatory motion in a direct manner to allow the loose material facings 8-charged with dust and/or noxious substances to trickle away, it is particularly advantageous for the intermittent oscillatory displacement of the supporting surfaces 7 to be performed in an indirect manner as will be described in the following with reference to Figures 4 to 7.

In this embodiment, in which the parts corresponding to those according to Figures 1 to 3 are given identical reference numerals, the pairs of layers 1 of loose material are combined in a cage or housing cage and installed as units within the filter housing 12, so that conventional filter housings may be utilised without substantial alteration and the structure of the filter is considerably simplified.

According to Figures 4 to 6, two loose material layers 1 combined into a pair and corresponding to those according to Figures 1 to 3, are delimited in each base towards the crude gas ingress side 5 by the loose material facings 8 on the supporting surfaces 7, and towards the side of the common purified gas chamber 11 by the covering strips 3 mounted in the manner of roof tiles. Towards the rear wall 1 2a of the filter housing 12, the pair of layers 1 is delimited by a wall 23 and with respect to the purified gas duct 15 by a wall 24 touching, or almost touching, the housing wall 13, the walls 23 and 24 being firmly joined to the ends of the supporting surfaces 7 and of the covering strips 3.

The base 4a of the cage is centrally interrupted in the longitudinal direction. This interruption 25 is situated between two horizontal supporting surfaces 4a and is covered by a cap 26, loose material facings 8a again being formed from the layers 1 on the supporting surfaces 4b between their two lateral bottom edges.

Each cage formed in this manner and comprising the two loose material layers 1, is suspended in supported manner from the roof 1 2b of the filter housing 12 by means of a linkage 9a via springs 27, and the linkage 9a has connected to it a vibrator 10 or an oscillation generator whereby the cage as a whole may be set in oscillation which is also transmitted to the supporting surfaces 7 and 4a and thereby causes the loose material of the facings 8, 8a to trickle downwards into the collector compartment 18.

The cage of each pair of layers 1 of loose material is joined in hermetic and elastic manner by upper reciprocally inclined walls 18, e.g. by bellows, to the roof 1 2b of the filter housing 1 2 where the filter layers 1 are in communication with the surrounding tube of the worm conveyor 17 whereby the layers 1 are replenished during or after the intermittent removal of the loose material facings 8. In doing so, the vibration and removal of the facings 8 and 8a ensure that the layers 1 are renewed in approximately uniform manner in all sections.

If the crude gas contains no dust particles or only a negligible amount of these, but contains noxious -substances or noxious gases, and if the loose material is appropriate by virtue of suitable selection to fix these noxious gases or noxious substances, the loose material trickling down from the supporting surfaces 7 and 4b is removed by a worm 19 in the bottom collector compartment 18, but is not recycled again.

In order that the loose material fixing noxious substances or noxious gases may be fully utilised, it is advantageous for the full height of the loose material layer at the inflow side to be acted upon by the crude gas, initially however allowing of intermittent removal from loose material facings on supporting surfaces in the lower section. To this end, according to Figure 7 is the formation of loose material facings 8 is arranged to take place only on supporting surfaces 7 situated in the lower section of the inflow side, whereas the superjacent section of the inflow side consists of covering strips 31, for example corresponding to the covering strips 3. Instead of these covering strips, other arrangements may also be provided, which allow of crude gas inflow into the loose material layer, but prevent egress of the loose material from the layer.

It is possible to alternate covering strips 31 with subjacently situated supporting surfaces 7 for loose material facings 8, as shown in Figure 7. In such case, the outer layer of the layer 1 is then acted upon by crude gas practically throughout the height of the layer 1, and loose material which had already fixed noxious substances or noxious gases above said facings may be removed only in the lower section of the inflow side by the supporting surfaces which may intermittently be set in oscillatory motion.

In the case of Figures 4 to 7 also, the pairs of layers 1 of loose material may be separated from each other by transverse partitions 20, the interruption of the cage wall 23 and of the housing wall 13 being arranged to be shut off from the crude gas supply by means of a slide 22 during intermittent renewal of the loose material facings 8 of a loose material pair.

It is also possible to subdivide only the purified gas duct 15 by partitions 29 (Figure 6) corresponding to the number of the loose material cages, and a closable throttle 30 is then installed in the off-take pipes of the individual duct chambers.

If the individual pairs of layers of loose material are acted upon by a crude gas which contains noxious substances or noxious gases only, but no dust particles, a subdivision of the cages is unnecessary either in the dust gas space or in the purified gas space, since the loose material simply drops downwards out of the loose material facings or slopes during the momentary intermittent oscillatory motion of the cages and is removed thereat without recirculation occurring.

Claims

1. A filter of the kind comprising a layer of loose filtering material, in which filter a crude gas containing dust and/or noxious substances flows into said layer whose content is replenish able from a stock, via uncovered loose material slopes formed within a housing on mutually parallel horizontal or approximately horizontal supporting surfaces, and emerges at the opposed outflow side retaining the loose material as purified gas, and which comprises a filter housing having a crude gas infeed, a delimiting wall of the layer of loose material at the inflow side being formed at least in the lower section of the housing by unconfined loose material facings which rest on supporting surfaces mounted on the housing and which surfaces are settable into intermittently oscillatory or tipping motion.

2. A filter as claimed in claim 1 , wherein the delimiting wall of the loose material layer in the upper section and at the inflow side consists in covering means allowing of inflow of the crude gas into the layer and retaining the loose material within the layer.

3. A filter as claimed in claim 1 or 2, wherein the delimiting wall at the inflow side consists of covering means and loose material facings alternating from top to bottom and allowing the crude gas to pass.

4. A filter as claimed in claim 2 or 3, wherein the covering means of the delimiting wall at the inflow side and the delimiting wall at the outflow side consist of covering strips arranged in the manner of roof tiles, which slope down towards the layer of loose material, are parallel, and are arranged one above another with mutual spacing.

5. A filter as claimed in any of the preceding claims, wherein two layers of loose material are arranged opposite to each other in the filter housing with the inflow sides and outflow sides delimiting the layers arranged symmetrically with the outflow sides facing towards each other, with mutual spacing, the spacing forming a purified gas chamber closed at one end side and connected at the other end side to a purified gas duct, shut off at the top from after-trickling loose material and closed at the bottom.

6. A filter as claimed in any of the preceding claims, wherein the supporting surfaces are mounted at one edge in articulated or flexible manner on the side of the layer of loose material and are connected at the outer edge to a linkage led out of the housing at the top thereof, the linkage being settable in vertical oscillation by means of a vibrator or a crank drive, with the supporting surfaces pivoting downwardly.

7. A filter as claimed in claim 4, 5 or 6, wherein the extremities of the covering strips are arranged in the manner of roof tiles at the outflow side, and the extremities of the supporting surfaces or their joints are connected to a rear wall and a front wall of the filter housing and wherein, in the area of the cross-section of the purified gas chamber, the front wall has perforations leading to the purified gas duct.

8. A filter as claimed in claim 5, wherein, within the filter housing, at least one pair of symmetrically arranged layers of the loose material are situated one behind another, and separated from each other by the purified gas chamber, are enflanked on all sides by a cage or housing having walls and which comprise an interrupted floor having inwardly directed supporting surfaces, with an upper covering of the interruption, the two loose material facings of the inflow sides, a rear wall rearwardly delimiting the purified gas chamber and a forwardly delimiting front wall which at least approximately touches the front wall of the housing and the perforation of which and a perforation of the front wall of the housing connect the purified gas chamber to the purified gas duct, whereas spaces are provided for the crude gas inflow, which are situated in front of the inflow sides of the loose material layers are supplied with crude gas and connected to a bottom settling compartment, and wherein the cage or the loose material layer housing is flexibly suspended and is intermittently settable in oscillatory motion by means of a vibrator means.

9. A filter as claimed in claim 5 or 8, wherein several pairs, each comprising two layers of loose material are installed one behind another within a filter housing having a bottom collector compartment provided with a discharge conveyor, said compartment receiving the loose material dropping out of the facings and coming from the layers of loose material during the intermittent oscillation of the supporting surfaces, and wherein a conveyor for feeding all the loose material layers is situated on an upper side of the filter housing.

10. A filter as claimed in claim 9, wherein the end of an upper conveyor feeding the loose material layers, leads, via a gravity duct, into one end of the collector compartment which is provided at the other end with an outlet and a regenerating device for the loose material, from which the regenerated loose material may be returned in a loop to the distributing conveyor.

1 1. A filter as claimed in claim 9, wherein the pairs of loose material are separated from each other by transverse walls of the filter housing, and the connection between the purified gas chambers and the purified gas duct is closable.

12. A filter as claimed in claim 9 or 10, wherein the purified gas duct is subdivided by transverse walls corresponding to the number of loose material cages, and a closable throttle valve is situated in the suction pipes.

1 3. A filter substantially as hereinbefore described with reference to Figures 1, 2 and 3 of the accompanying drawings.

14. A filter substantially as hereinbefore described with reference to Figures 4 to 7 of the accompanying drawings.