GB2130115A

GB2130115A - A filter for purifying gas or air streams

Info

Publication number: GB2130115A
Application number: GB08312271A
Authority: GB
Inventors: Hans-Georg Dillmann; Horst Pasler
Original assignee: Kernforschungszentrum Karlsruhe GmbH
Current assignee: Forschungszentrum Karlsruhe GmbH
Priority date: 1982-09-18
Filing date: 1983-05-05
Publication date: 1984-05-31
Also published as: FR2533142B1; DE3234674A1; IT8353467V0; FR2533142A1; GB2130115B; BE897729A; NL8301466A; IT8367662A0; GB8312271D0; DE3234674C2

Abstract

A filter for purifying gas or air streams, more especially for purifying spent air of nuclear plants containing radioactive substances in cases of malfunction, comprises steel fibre mats (15) wrapped round a hollow support grid (13). The filter is securely connected to a housing end wall (8) which is provided with a filtered air outlet pipe connection (4) and can be removed from the housing (1), to enable the filter to be replaced. The other end of the filter is closed by a plate (19) which carries a hook (25) releasably engaging a bar (26) fixed to the housing to support the filter therein. The whole unit is made of steel with high temperature resistance and stability to radiation. <IMAGE>

Description

SPECIFICATION A filter housing for purifying gas or air streams The present invention relates to a filter housing for purifying gas or air streams, more especially for purifying spent air of nuclear plants containing radioactive substances in case of malfunction.

Filter housings are known which have filter inserts comprised of glass fibre paper in wood or steel frames together with organic fillers and sealing compounds. However, these filters are not temperature-resilient, have little stability to radiation, have a poor mass storage capacity and have low mechanical stability.

The present invention seeks to provide a filter housing having a changeable filter insert for filtering the safety atmosphere in the event of any serious malfunctions in nuclear plants, such a filter housing having the suspended material filter, the preliminary or coarse filter and the separator combined in one component and also having as low a drop in pressure as possible with a high separating output and a high degree of resistance to disturbing influences.

According to the present invention there is provided a filter housing for purifying gas or air streams, more especially for purifying spent air of nuclear plants containing radioactive substances in cases of malfunction, such a filter housing having the following features: a) the end walls of the housing are provided with respective inflow and outflow pipe connections; b) an approximately annular filter packet comprising a bundle of filters, having smaller dimensions than the housing, is disposed in the housing between the inflow and outflow chambers associated with each inflow and outflow pipe connection on a support structure comprised of tubes or on a support grid or lattice support; c) the filter packet in the housing is traversed radially inwardly from the outside; the purified gas is discharged axially from the interior of the filter packet; and an end aperture, which communicates with the outflow pipe connection, extends through the filter packet; d) the filter layer of the filter packet is comprised of metal fibre mats which are radially retained externally and internally by means of transversable retaining sieves or screens, in which the filter housing has the following additional features; e) the end face of the support grid or lattice support facing the inflow chamber is sealed by a cover plate which is securely clamped at its edge to one fibre mat end of the filter material layer wound onto the support grid or lattice support; f) a hollow box facing the outflow end is mounted on the other end of the support grid or lattice support, and the interior of the hollow box joins the inside of the filter packet to the outlet pipe connection;; g) the cross-section of the box corresponds approximately to the shape of the filter packet and the other fibre mat end of the filter material layer wound onto the support grid or lattice support is tightly and securely clamped to the periphery of the box which is tightly inserted into the housing wall associated with the outlet pipe connection; h) the cover plate is detachably hooked to the housing; and i) the wall is tightly attached to the housing and, together with the box, the filter packet and the cover plate is detachable from the housing in order to permit the filter packet to be changed.

Also according to the present invention there is provided a filter housing for purifying gas or air streams, more especially for purifying spent air of nuclear plants containing radioactive substances, for example, in the event of any malfunction, such a filter housing having the following features: k) the end walls of the housing are provided with respective inflow and outflow pipe connections; I) a filter packet, having smaller dimensions than the housing, is inserted in the housing between the inflow and outflow chambers associated with each inflow and outflow pipe connection on a support structure; m) the filter layer of the filter packet is comprised of metal fibre mats which are externally and internally retained by means of traversable retaining sieves or screens; in which the filter housing has the following additional features; n) the filter packet includes a disc-shaped, hollow intermediate housing having open lateral faces, a box being connected to the periphery of the intermediate housing, and the interior of such box being open in the direction of the interior of the intermediate housing; o) the box is connected to the outlet pipe connection and extends, in a sealed manner, through the wall in which the box is mounted; p) retaining sieves or screens are inserted into the open lateral faces; q) filter mats are placed upon the retaining sieves or screens and are securely clamped to the periphery of the lateral faces of the intermediate housing; r) the intermediate housing is detachably hooked to the filter housing; and s) the wall is tightly attached to the filter housing and, together with the intermediate housing, the box and the filter packet, is detachable from the housing in order to permit the filter packet to be changed.

The arrangements referred to above provide a particularly advantageous suspended material filter of Class S having the following advantageous properties: 1. the suspended material filter, the drip separator and the preliminary or coarse filter form one unit; 2. there is a temperature resistance to approximately 5500C: 3. the filter is stable to radiation up to high doses; 4. a very low drop in pressure results with a simultaneous high mass storage capacity; 5. there is high mechanical stability, even during any malfunction; 6. the filter can be cleaned, it is resistant to humidity, vapour and water, and is unaffected by corrosion and solvent vapours.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic, side elevational view of a fragmented housing in accordance with the invention; Fig. 2 is a sectional view taken along the line A-B of Fig. 1; Fig. 3 is a sectional view taken along the line C-D of Fig. 1; Fig. 4, like Fig. 1 is a side elevational view of another embodiment of a housing insert, or filter packet, respectively; and Fig. 5 is a sectional view taken along the line E-F of Fig. 4.

As illustrated, the gas stream 5 to be purified horizontally traverses the interior 2 of the housing 1 from the inlet pipe connection 3 to the outlet pipe connection 4. The inlet pipe connection 3 is inserted into the lateral wall 6 of the housing 1 and extends to the inflow chamber 7 which forms the portion of the interior 2 located in front of the filter.

The opposite wall 8 of the housing 1 is removably secured by means of screws 9 and is sealed by means of the seal 10. A hollow box 1 1 is tightly inserted into this wall 8, the interior 24 of such box 11 forming the outflow chamber and being connected to the output pipe connection 4 by means of connecting member 12, which is likewise hollow. A support grid or lattice support 13 is laterally mounted at the aperture in this hollow box 11 and has approximately the oval shape of a compressed ring. The periphery of the box 11 has approximately the same cross-section as the lattice support 13 which is mounted on such periphery and extends horizontally through the entire housing 1 up to the vicinity of the lateral wall 6.Filter material 15 is annularly wound on the periphery 1 6 of the lattice support 13, and in such case the filter material 15, comprised of metal fibre mats wound in web fashion onto the periphery 16, is provided with the required, radial support by external retaining sieves or screens 18 and internal retaining sieves or screens 14 which are in the form of perforated sheets or wire grids.

The mats are made from a non-woven high-grade steel fibre material having a fibre diameter of 4 and 2 ym. In such a case, a multi-layered 2 Mm non-woven fibre material has proved satisfactory for the separation of 0.1 ssm particles, such a material being provided with both a bottom layer and a top layer made from coarser fibres for easier operation. The actual hollow filter packet 17, which is disposed horizontally with its axis 27 and surrounds the interior 23, is therefore comprised of the components 13 to 18 and is radially traversed from its periphery inwardly. For this purpose, the end of the lattice support 13 facing the inlet pipe connection 3 is sealed by a front plate 19, one end 21 of the fibre mats 1 5 being securely clamped over this periphery on the encircling edge 20 of the front plate 19.The other end 22 of the fibre mats 1 5 is securely clamped to the periphery of the box 11, so that an oval filter packet is produced, one end of such packet being sealed by the plate 19, and the spent air being conducted through the other end of the filter packet to the outlet pipe connection 4 via the box 1 1 and through the connecting member 12.

A hook member 25 is secured to the plate 19 facing the inlet pipe connection 3 and is hooked into the frame 26 connected to the housing 1.

Other retaining means are also feasible instead of this arrangement. One side of the filter packet 1 7 is therefore retained in the centre of the housing.

As already described, the other side is retained by the housing wall 8. Thus, once the screws 9 have been loosened, the filter packet 17 can easily be unhooked from the frame 26, extracted horizontally from the housing 1 and replaced. A trough 28 is disposed on the base of the housing 1 and has a discharge pipe connection 29 through which liquid can be extracted, such liquid being eventually separated at the filter packet 17.

Figs. 4 and 5 illustrate a housing wherein the filter insert has a somewhat different shape.

Basically, the housing 101 is the same as the housing 1 illustrated in Figs. 1 to 3, but the filter material 11 5 is not applied to an annular grid or lattice arrangement, but is applied to the open lateral face 1 13 of an intermediate housing 1 14.

The gas stream 105 to be purified traverses the interior 102 of the housing 101 also from the inlet pipe connection 103 to the outlet pipe connection 104. The inlet pipe connection 103 is inserted into the lateral wall 107 and is open in the direction of the inflow chamber 106 forming a portion of the interior 102. The outlet pipe connection 104, together with its associated component 1 10 and 1 1 1, is secured in the opposite wall 108 which is detachably and sealingly screw-connected to the housing 101 by means of screws 109. In such case, the connection between the outflow pipe connection 104 and the housing interior 102 is formed by the conical transitional member 1 10, directly mounted on the pipe connection 104, and the box 111 which is connected to the transitional member 1 10 and has a wall which is tightly inserted into the removable lateral wall 108 of the housing 101. The components hitherto described are identical to those of Fig. 1.

The box 111 which, in Figs. 1 to 3 practically forms the axial extension of the oval support grid or lattice support, is here, however, inserted into the periphery of a disc-shaped hollow intermediate housing 1 14, the interior 116 of which forms the outflow chamber behind the filter material. The lateral faces 11 3 of the intermediate housing 1 14 are open, and internal retaining sieves or screens 1 12 are inserted into the apertures.

The actual filter material 1 15, i.e. high-grade steel fibre mats of the already mentioned type, is now placed upon the internal retaining sieves or screens 1 12, such mats engaging over the edge 1 8 of the intermediate housing 1 14 and being securely clamped thereto. The external retaining sieves or screens 11 9 form the outer limit of the filter material 1 5, and hence the outer limit of the entire filter packet 1 17, and the external retaining sieves or screens 1 9 are clamped to one another or to the intermediate housing 1 14, respectively, by means of the clamps 120. Supporting pipes 121 are inserted into the interior 1 16 in a crosswise manner and provide the filter packet 1 17 with radial support.

As with the filter packet in Figs. 1 and 2, the entire filter packet 1 17 is now hooked in a frame portion 123 of the housing 101 by means of a hook member 122; in order to change the filter material or the entire unit, the entire filter packet 1 17 can easily be unhooked and removed once the screws 109 have been loosened.

Claims

1. A filter housing for purifying gas or air streams, more especially for purifying spent air of nuclear plants containing radioactive substances in cases of malfunction, such a filter housing having the following features: a) the end walls of the housing are provided with respective inflow and outflow pipe connections; b) an approximately annular filter packet comprising a bundle of filters, having smaller dimensions than the housing, is disposed in the housing between the inflow and outflow chambers associated with each inflow and outflow pipe connection on a support structure comprised of tubes or on a support grid or lattice support: c) the filter packet in the housing is traversed radially inwardly from the outside; the purified gas is discharged axially from the interior of the filter packet; and an end aperture, which communicates with the outflow pipe connection, extends through the filter packet; d) the filter layer of the filter packet is comprised of metal fibre mats which are radially retained externally and internally by means of traversable retaining sieves or screens in which the filter housing has the following additional features; e) the end face of the support grid or lattice support facing the inflow chamber is sealed by a cover plate which is securely clamped at its edge to one fibre mat end of the filter material layer wound onto the support grid or lattice support; f) a hollow box facing the outflow end is mounted on the other end of the support grid or lattice support, and the interior of the hollow box joins the inside of the filter packet to the outlet pipe connection;; g) the cross-section of the box corresponds approximately to the shape of the filter packet and the other fibre mat end of the filter material layer wound onto the support grid or lattice support is tightly and securely clamped to the periphery of the box which is tightly inserted into the housing wall associated with the outlet pipe connection; h) the cover plate is detachably hooked to the housing; and i) the wall is tightly attached to the housing and, together with the box, the filter packet and the cover plate, is detachable from the housing in order to permit the filter packet to be changed.

2. A filter housing for purifying gas or air streams, more especially for purifying spent air of nuclear plants containing radioactive substances, for example, in the event of any malfunction, such a filter housing having the following features; k) the end walls of the housing are provided with respective inflow and outflow pipe connections; I) a filter packet, having smaller dimensions than the housing, is inserted in the housing between the inflow and outflow chambers associated with each inflow and outflow pipe connection on a support structure; m) the filter layer of the filter packet is comprised of metal fibre mats which are externally and internally retained by means of traversable retaining sieves or screens; in which the filter housing has the following, additional features; n) the filter packet includes a disc-shaped, hollow intermediate housing having open lateral faces, a box being connected to the periphery of the intermediate housing, and the interior of such box being open in the direction of the interior of the intermediate housing; o) the box is connected to the outlet pipe connection and extends, in a sealed manner, through the wall in which the box is mounted; p) retaining sieves or screens are inserted into the open lateral faces; q) filter mats are placed upon the retaining sieves or screens and are securely clamped to the periphery of the lateral faces of the intermediate housing; r) the intermediate housing is detachably hooked to the filter housing; and s) the wall is tightly attached to the filter housing and, together with the intermediate housing, the box and the filter packet, is detachable from the housing in order to permit the filter packet to be changed.

3. A filter housing for purifying gas or air streams, substantially as hereinbefore described with reference to Figs. 1, 2 and 3 or Figs. 4 and 5 of the accompanying drawings.