GB2256237A - Treatment plant with sealing to prevent escape of gases - Google Patents

Abstract

A treatment plant comprises side walls and a roof (14) provided with a longitudinal extending opening (16), in the form of a through-extending slot or channel, through which a support element in the form of cable (17) extends downwardly into the chamber from a hoist, by operation of which the article to be treated may be lifted into and out of a treatment bath, and conveyed longitudinally of the treatment plant, passing through the side doors thereof. To reduce the escape of noxious gases through the opening (16), sealing means is provided extending across the opening (16), said sealing means comprising elongate sealing-members (18a, 18b) in the form of strips of a resilient elastomeric material, such as rubber, being of inverted V-shape in cross section. As the cable (17) passes between the sealing members (18a and 18b), they are flexed separatively to facilitate movement of the cable (17) in the longitudinal direction. In an alternative construction the opening (116) Fig 7 (not shown) through which the cable (117) extends is provided in a supplementary chamber (130), sealing means (118) being provided to embrace the cable (117) in a similar manner to that previously described. In the modified construction, an outlet (140) extends from the supplementary chamber, to ducting (142) of the extraction plant, to provide for low pressure in the immediate vicinity of the opening (116), to remove air and noxious gases from the area of the plant where they are most prone to leakage into the external environment. <IMAGE>

Description

Title: "Fume extraction system" Description of the Invention This invention is concerned with systems for the extraction of fumes, and in particular to a system for more readily extracting fumes from a plant treatment system.

Problems are encountered in the extraction of fumes from an enclosed area afforded by a treatment chamber, where it is necessary to have a movable member extending into the treatment chamber, e.g. for movably supporting an object whilst being treated in said chamber.

For example, a hot dip galvanising process involves transferring a steel object to an enclosure, and lowering the object into a bath of molten zinc in the enclosure. When galvanising has been completed, the object is lifted from the bath, and moved from the treatment chamber, e.g. through doors.

To accomplish this, an element of a hoist must pass into the treatment chamber, and be movable relative thereto, e.g. in a horizontal direction, in addition to being capable of effecting the necessary vertical movement of the object as it is lowered into and removed from the treatment bath.

In general this requires the provision in a roof structure bounding the treatment chamber, of a longitudinal extending opening through which the hoist element extends.

Difficulty is encountered in minimising the escape of noxious fumes at the interface between the slot and hoist element. This difficulty is exacerbated by strong upward convection currents which are generated on the surface of the bath of molten zinc, particularly on immersion of the object into the bath, when a large volume of fume is generated, which is immediately carried up in the rising convection currents to the roof structure.

Conventionally escape of noxious fumes in this situation is minimised by the use of an extraction unit to ensure that the fumes do not pass through the slot. However this requires the use of an extraction unit of high power, and correspondingly high filtration capacity, with high installation and running costs.

According to this invention there is provided a treatment plant comprising a treatment chamber and a support member for supporting an object for movement in the chamber, the plant comprising walls bounding the enclosure and defining an elongate slot or opening through which the support member extends, wherein there is provided, operative across the opening, sealing means comprising two sealing members which are urged together to close the opening and of which at least one may be flexed separatively to permit passage of the support member longitudinally of the opening.

One of the sealing members may be afforded by part of the wall bounding the opening along one side thereof, the other sealing member being urged against said wall part to close the opening other than where the support member passes through the opening, where it is flexed away from said wall part.

Preferably said other sealing member is resiliently deformable, at rest adopting an operative position in which it engages said one sealing member to close the opening, being capable of being flexed against its own resilience to permit passage of said support member longitudinal of the opening.

It is however envisaged that the said other sealing member may be urged to its operative position by separate pressure applying means, e.g. in the form of an additional resiliently deformable member, or by pressure applying means in the form of a plurality of hydraulic or spring devices.

Preferably however both sealing members are resiliently deformable and are urged into mutual contact to seal the opening by their own resilience.

Preferably the construction and arrangement of the sealing members is such that, in cross-section transverse to the length of the opening, they are of V-shape, preferably inverted V-shape.

The invention above defined is particularly suitable for a structure wherein the support member is in the form of a rope or cable, extending through a roof of the plant to move the object being treated in a height-wise direction, and translationally with the support member in a horizontal direction. It is however to be understood that the invention may be utilised where the support member is rigid, and where such rigid support member extends into the chamber other the vertically. For example the support member may be in the form of a rigid bar extending through a side wall of the treatment chamber, e.g.

horizontally, for translational movement of an object within the chamber.

According to this invention there is also provided a treatment plant comprising a treatment chamber and a support member for supporting an object for movement in the treatment chamber, the plant comprising walls bounding the chamber and defining an elongate slot or opening through which the support member extends and along which the support member may travel, wherein the opening extends into a supplementary enclosure or chimney exteriorly of the treatment chamber with the support member extending through said supplementary enclosure, extraction means being provided to withdraw air and gases from said supplementary enclosure, sealing means being provided to reduce the escape of gases from the supplementary enclosure.

Particularly where the sealing means is as set out in the last preceding paragraph but six. By withdrawing air and gases from the supplementary enclosure, highly effective prevention of discharge of noxious fumes may be obtained with relatively low air extraction volumes.

There will now be given detailed descriptions, to be read with reference to the accompanying drawings, of embodiments which have been selected for the purposes of illustrating the invention by way of example.

In the accompanying drawings: FIGURE 1 is a schematic plan view illustrating one aspect of the invention in principle, FIGURE 2 is a sectionally view on the line 2-2 of Figure 1; FIGURE 3 is a half section/side elevation of a treatment plant which is a preferred embodiment of the invention; FIGURE 4 is a plan view of the preferred embodiment; FIGURE 5 is a half section/end elevation of the preferred embodiment; FIGURE 6 is an end elevation of the preferred embodiment, various items having been removed for the purposes of clarity; and FIGURE 7 is an enlarged view of part of Figure 6.

Figure 1 shows in plan view a schematic treatment plant 10 wherein an article may be treated, such as a steel object treated in a galvanising process.

The treatment plant 10 comprises side walls 12, enclosing in conventional manner a treatment bath, said side walls 12 including a door (not shown in Figure 1) for entrance of the object to be treated into the treatment chamber.

A roof 14 of the plant is provided with a longitudinal-extending opening 16, in the form of through-extending slot or channel, through which a support element, in the form of a cable 17 extends downwardly into the chamber from a hoist (not shown). By conventional operation of the hoist, the article to be treated maybe lifted into and out of the treatment bath, and may be conveyed longitudinally from the treatment plant,passing through the side doors thereof, the cable 17 travelling longitudinally of the opening 16, as is shown by the directional arrows of Figure 2.

To reduce the escape of noxious gases through the opening 16, sealing means is provided extending across the opening 16, said sealing means comprising sealing members 18a, 18b in the form of strips of a resilient elastomeric material, such as rubber. In the schematic illustration of Figure 2, the sealing members 18a and 18b are secured to the underside of the roof 14 adjacent to the opening 16, and have sealing portions which are inclined upwardly into contact with one another, so that the sealing means is in the form of an inverted V-shape in crosssection. The cable 17 passes as is shown between the sealing members 18a and 18b. which are flexed separatively to permit passage of the support member 18 longitudinally of the opening.

In this manner the only opening from the plant necessary to accommodate for the support member is in the form of a short slit 22 through which the cable 17 extends.

Referring now to the detailed drawings of the preferred embodiment, referring particularly to Figures 6 and 7, in which similar numerals with the prefix 1 has been utilised, mounted on the roof 114 over the opening 116 is a supplementary chamber 130, through which the cable 117 extends into the treatment chamber, the sealing means 118 being provided by rubber sealing strips 118ss, 118b operative in a similar manner to embrace the cable 117, and to engage one another to prevent the escape of noxious fumes from the opening 116 to the external environment. As is shown in Figure 7, the sealing members 118g, 118b are supported with backing plates 120, to support the rubber sealing members, and to assist them in their mutual engagement and in the engagement around the cable 17.

Extending from the supplementary chamber, generally the full length of the plant 110, is an outlet 140, connected by ducting 142 to an extraction plant.

In this manner low pressure is provided by the extraction plant in the immediate vicinity of the opening 116, and ensure that air and noxious gases are removed from the area of the plant where they are most prone to leakage into the external environment.

In addition, by creating a slightly lower pressure within the supplementary chamber 130, the rubber sealing members 118 , 118b are drawn more closely together, thereby ensuring a tighter air seal, particularly in the vicinity of the cable 117.

In this manner an extraction plant of lower capacity may be utilised with greater effectiveness, reducing the capital outlay in providing the plant, and the filtration area required to deal with the volume of air being withdrawn, thus reducing running costs.

Additionally if desired a supplementary opening 144 may be provided in the ducting 142, enabling the direct extraction of air from the chamber, allowing the noxious fumes containing therein to be treated.

It is to be appreciated that whilst the invention has been described be primarily in relation to a hot dip galvanising process, the invention may be utilised in other plant and apparatus, where similar or analogous problems arise, and in particular where it is desired to prevent the escape of noxious fumes from an enclosed environment, into which a supporting member is required to extend and be movable relative thereto, for the support and positional transfer of an article in the treatment chamber.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in the terms or means for performing the desired function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (14)

1. A treatment plant comprising a treatment chamber and a support member for supporting an object for movement in the chamber, the plant comprising walls bounding the chamber and defining an elongate slot or opening through which the support member extends, wherein there is provided, operative across the opening, sealing means comprising two sealing members which are urged together to close the opening and of which at least one may be flexed separatively to permit passage of the support member longitudinally of the opening.

2. A treatment plant according to Claim 1 wherein one of the sealing members is afforded by part of the wall bounding the opening along the side thereof, the other sealing member being urged against said wall part to close the opening other than where the support members passes through the opening, where it is flexed away from said wall part.

3. A plant according to Claim 2 wherein said other sealing member is resiliently deformable, at rest adopting an operative position in which it engages said one sealing member to close the opening, being capable of being flexed against its own resilience to permit passage of said support member longitudinal of the opening.

4. A treatment plant according to Claim 2 wherein said other sealing member is urged to its operative position by separate pressure applying means.

5. A treatment plant according to Claim 4 wherein said separate pressure applying means is in the form of an addition resiliently deformable member.

6. A treatment plant according to Claim 4 wherein said separate applying means is in the form of a plurality of hydraulic or spring devices.

7. A treatment plant according to any one of the preceding claims wherein both sealing members are resilient deformable and are urged into mutual contact to seal the open by their own resilience.

8. A treatment plant according to any one of the preceding claims wherein the sealing members are such that, in cross-section transverse to the length of the opening, they are of V-shape, preferably inverted V-shape.

9. A treatment plant according to any one of the preceding claims wherein the support member is in the form of a rope or cable extending through the roof of the plant to move objects being treated in a height-wise direction, and translationally with the support member in a horizontal direction.

10. A treatment plant according to any one of Claims 1 to 8 wherein the support member is rigid.

11. A treatment plant comprising a treatment chamber and a support member for supporting an object for movement in the treatment chamber, the plant comprising walls bounding the chamber and defining an elongate slot or opening through which the support member extends and along which the support member may travel, wherein the opening extends into a supplementary enclosure or chimney exteriorly of the treatment chamber with the support member extending through said supplementary enclosure, extraction means being provided to withdraw air and gases from said supplementary enclosure, sealing means being provided to reduce the escape of gases from the supplementary enclosure.

12. A treatment plant according to Claim 11, being in accordance also with any one of Claims 1 to 10.

13. A treatment plant constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

14. Any novel feature or novel combination of features as hereinbefore described and/or as shown in the accompanying drawings.