GB2181669A

GB2181669A - Gas filter

Info

Publication number: GB2181669A
Application number: GB08622160A
Authority: GB
Inventors: Theo Schiffers
Original assignee: H Krantz GmbH and Co
Current assignee: H Krantz GmbH and Co
Priority date: 1985-10-22
Filing date: 1986-09-15
Publication date: 1987-04-29
Also published as: IT8621822A1; JPS6287721U; DE3537440A1; FR2588769A1; BR8604403A; IT1197283B; IT8621822A0; GB8622160D0

Abstract

Gas which is used for treating a textile web, e.g. in a tenter frame, is continuously circulated by one or more blowers 1 through a moving filter screen 4 to remove fibres. The fibres are blown from the screen where it passes a fixed nozzle 8, which is fed with gas from the downstream side of the blower(s). As shown the screen is a rotary filter drum. In Figures 3, 4 a screen in the form of a filter band is moved to and fro across a central plenum leading to the blower intake, flanked by two nozzles supplied with gas from the blower outlet. <IMAGE>

Description

SPECIFICATION Apparatus for the continuous filtering of a gas This invention relates to apparatus for the con tinuous filtering of a gas which is circulated byway of a blower and a flow duct and which serves for the heat treatment of goods in web form.

For example, conventional tenterframes for the heat treatment of a textile web are equipped with such device, in which the web crosses or intersects the flow path of the treatment gas, which is conducted in a circuit, and in so doing is acted upon bythe gas. During this treatment, particles from the textile web, more especially slubs, bits offluff orthreads, accumulate in the gas, and in orderto avoid continuously increasing the contact of the foreign matter in the gas, such matter is filtered out of the gas stream prior to it acting again upon the web.

Generally known forms ofapparatusforthe continuousfiltering of a circulated gas normally consist of a screen which crosses or intersects the flow path of the gas in the same way as the web undertreatment and which extends over the cross-section thereof. In this way, the entire volume ofgas, upon each flow circuit, is perforce conducted through the screen and thus continuously filtered.

A particle layer, for example of slubs, arises on the screen, and this layer builds up progressively. As a resu It, the flow resistance to the circulated treatment gas increases, so that the treatment efficiency decreased. It is therefore necessary, during operation, to clean the screen off at comparatively short intervals oftime. In the previously known filter apparatus the treatment process has to be interrupted, the screen hasto be exposed and to be cleaned offmanually.

The consequential operational interruptions are not only bound up with excessive expenditure of time and energy, but can also lead to non-uniform web treatment if,forexample, during the cleaning-offop eration, the web, itself running continuously through atenterframe, has to be halted and the portion ofthe web present in the te nter fra m e is thereby exposed, over an excessively long dwell duration, to the high treatment temperatures normally prevailing in the tenterframe.

The problem underlying the invention isto provide apparatus for the continuous filtering of a circulated gas which can be kept in the functional state without interruption of operation.

To solve this problem, the invention provides apparatus for the continuous filtering of a gas which is circulated byway of a blowerand a flow duct and which servesforthe heat treatment of goods in web form, in which the gas impinges on the web crossing the flow duct and thereby accumulates particles from the web, which particles are arrested by a screen which likewise crosses the flow duct and which extends over the cross-section thereof, characterised in that at least one stationary pipeline is connected to the flow duct in the vicinity ofthe pressure side ofthe blower, which stationary pipeline leads to the rear side of the screen and is provided with an outlet slot which extends over one dimension of the screen which is movable in the direction perpendicularto the longitudinal extent oftheoutlet slot.

By reason of the connection of the pipeline in the vicinity of the pressure side of the blower, in accordance with the arrangement of the invention, the pipeline is acted upon by a part of the circulated gas. In the arrangement of the invention the gas passes by way of the pipeline to the rear side of the screen and emerges by way of an outlet slot (in the place of which, naturally, a row of holes may be provided) as scavenging gas against the rear side of the screen.

The concentration of the emerging scavenging gas jet and the impulse resulting therefrom are sufficient to penetrate the screen from the rear side thereof againstthegascirculationflowandtokeepthe screen free from accumulating material. Since the outlet slot in the arrangement of the invention extends over one dimension of the screen and the screen is movable in the direction perpendicular to the longitudinal extent of the outlet slot provided in the stationary pipeline, as a result of this design and arrangement the entire screen surface can be continuously cleaned off in stripwide manner.

If a radial fan is provided as the blowerfor maintaining the circulation of the gas, in accordance with a preferred development of the invention the screen then preferably consists of a rotatable drum, the jacket or outer curved surface of which forms the screen surface acted upon radially from the outside inwardly.

In such embodiment, the pipe is preferably so arranged stationarilywith its outlet slot in the interior of the rotatable drum that the outlet slot is directed towards the jacket inside and extends over the drum of the width of the curved surface thereof. If the blower consists of two coaxially-arranged radial fans the suction sides of which are turned to one another, the rotatable drum is preferably arranged between the radial fans and bridges the gaptherebetween.

Upon the rotation of the drum, the complete screen surface is continuously cleaned off in stripwise manner.

If atransverse-flowfan is provided as the blower for maintaining the circulation of the gas, in accordance with another development of the invention pre ferablyconnectedtoeachsidethereofisa respective pipeline, which pipelines lead to the rear side of the screen, consisting of a web, which can be moved to and fro.

In this embodiment, one half each of the active screen web surface is cleaned off by one outlet slot each of the two pipes. The outlet slots are in turn again directed towards the rear side of the screen, so that in this embodiment, too, upon the reciprocating movement of the screen by an amount which corresponds to half the screen web length, the screen web surface is continuously cleaned off in stripwise manner.

Finally, in accordance with a further development of the invention, arranged on the front side of the screen is, in each case, an inlet aperture, lying oppositethe outlet slot, of a collecting container for par- ticles detached from the screen.

With this development, the particles filtered out of the gas bythe screen cannot pass back into the circulation, but are trapped in the collecting container which can be emptied from time to time withoutthe need for interruption of the operation of the apparatus.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which Figure 7 is a vertical section through a first embodimentofthe apparatus of the invention, being a drumshaped screening installation associated with a radial fan; Figure 2 is a horizontal cross-section taken along the line Il-Il of Figure 1; Figure 3 is a vertical cross-section through a second embodiment of the apparatus of the invention, being a web-shaped screening installation associated with atransverse-flowfan; Figure 4 is a horizontal cross-section taken along the line IV-IV of Figure 3.

In the exemplified embodiment of Figures 1 and 2, two radial fans (or centrifugal fans) 2 are arranged coaxially and at a spacing from one another, their suction sides 3 being turned towards one another.

Arranged between the radial fans 2 is a screen 4 which consists ofthe jacket or outer curved wall Sofa drum 6 which is mounted so asto be rotatable about an axis parallel to the axial of the radial fans 2 and is caused to revolve at a comparatively slow rotational speed by way of a gearing (not shown).

Connected to pressure sides 7 of the radial fans 2 are the respective ends of a pipeline 8 which extends closely adjacent to the inside surface ofthe jacket 5 of the drum 6 at a parallel spacing relative to the rear side of the screen 4,so that the inside ofthejacket S almosttouches the outer periphery of the pipeline 8.

In this region, the pipeline 8 is provided with an outlet slot 9 which is open to the rear side of the screen 4 and which extends over the width of the drum 6.

An inlet aperture 10 of a stationary collecting con tainer 11 extends likewise over the width of the drum 6 and is so arranged outside the outer periphery of the drum 6 that the outlet slot 9 lies centrally opposite the inlet aperture 10.

In the exemplified embodiment of Figures 3 and 4, a transverse-flow fan 2' is arranged as blower 1 in a circuit the rest of which is not shown. Arranged on a suction side 3' of the transverse-flow fan 2' is a screen 4' which consists of a web 5' which can be moved to and fro as indicated bythe double arrow and which extends over the cross-section of the circuitflow.

Connected oppositely on the pressure side 7' ofthe transverse-flowfan 2' and stationarily are two pipelines 8' which open out into respective triangular ducts 12. The two triangular ducts 12 are arranged parallel to one another and at a spacing from one another, and each extends with a respective outlet slot 9', extending over its length, over the width of the web 5', which can be moved to and fro, of the screen 4'.

At the side lying opposite to the web S' an inlet aperture 10' of a stationary collecting container 11' is so associated with each outlet slot 9' that each outlet slot 9' lies centrally opposite the relevant inlet aperture 10'.

Particles from gas circulated by means of the radial fans in the exemplified embodiment of Figures 1 and 2 orthetransverse-flowfan in the exemplified embodiment of Figures 3 and 4 are arrested bythe screen 4 or 4' respectively and are continuously removed, in stripwise manner, from the screen 4 or 4' re spectiveiy by a scavenging gas stream, branched off from the gas stream and acting upon the pipeline 8 or pipelines 8', which cleans offthe screen 4 or4' respectively and blows the particles, such as slubs or the like, by way of the inlet aperture 10 or 10' respectively into the collecting container 11.

Claims

1. Apparatus forthe continuous filtering of a gas which is circulated by way of a blower and a flow duct and which serves for the heat treatment of goods in web form, in which the gas impingesonthewebcos- sing the flow duct and thereby accumulates particles from the web, which particles are arrested by a screen which likewise crosses the flow duct and which extends over the cross-section thereof, chracterised in that at least one stationary pipeline is connected to the flow duct in the vicinity of the pressure side of the blower, which stationary pipeline leads to the rear side of the screen and is provided with an outletslotwhich extends over one dimension of the screen which is movable in the direction perpendicularto the longitudinal extent of the outlet slot.

2. Apparatus as claimed in claim 1, characterised in thatat leastone radial fan is provided asthe blower and the screen consists of a rotatable drum the exterior or jacket of which forms the screen surface which can be acted upon radially from the outside inwardly.

3. Apparatus as claimed in claim 1, characterised in that a transverse-flow fan is provided as the blower, and connected to the fan on both sides is a respective pipeline which leads to the rear side of the screen which consists of a web which can be moved to and fro.

4. Apparatus as claimed in claim 1,2 or 3, char- acterised in that a respective inlet aperture is arranged on the front side of the screen, each said inlet aperture lying opposite the respective outlet slot of a collecting container for particles detached from the screen surface.

5. Apparatus for the continuous filtering of a gas which is circulated by way of a blower and a flow duct, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.