GB2164870A

GB2164870A - Fluid filter

Info

Publication number: GB2164870A
Application number: GB08424800A
Authority: GB
Inventors: Dennis Albert George Marshall
Original assignee: Marshall D A G
Current assignee: Marshall D A G
Priority date: 1984-10-02
Filing date: 1984-10-02
Publication date: 1986-04-03
Also published as: GB2164870B; GB8424800D0

Abstract

A two-stage fluid filter element comprises an annular compartment formed between two meshes (22 and 24) and enclosing an outer layer (30) of cellular aluminium and a mass of activated carbon granules which are tightly packed into the compartment and into all the cells of the layer (30). Radially outside or inside of the compartment (28) there is a pleated paper layer (34) serving as a high efficiency mechanical filter medium which acts in series with the carbon granules to purify air and other gases. The carbon may be impregnated with triethylene diamine, to remove iodine compounds such as methyl iodide from air. <IMAGE>

Description

SPECIFICATION Fluid filter This invention relates to fluid filters. More specifically it relates to fluid filters containing activated carbon granules or particles for the removal of noxious substances (especially iodine compounds) from air and other gaseous streams.

In broad terms, the invention is directed to a fluid filter of generally cylindrical shape comprising an annular compartment containing activated carbon granules or particles and, on the inside or outside of that compartment, a high-efficiency filter element preferably of pleated filtering material-so that air or other gas to be filtered is made to pass through the said two filtering media in succession, there being an annular cellular layer arranged along the outer perimeter of the compartment containing the activated carbon granules or particles with the cells of the cellular layer and the space between the cellular layer and the inner perimeter of the said compartment being packed tightly with the activated carbon granules or particles.

An example of a fluid filter in accordance with the invention is shown in the accompanying drawings, in which Figure 1 is a perspective view from above of the filter with an upper lid or cap removed; Figure 2 is a vertical section through the filter; Figure 3 is a section taken on the line Ill-Ill in Figure 2; and Figure 4 is an enlarged perspective view of part of a cellular layer provided in the filter.

The fluid filter shown in the drawings is designed for the removal of iodine compounds and other noxious substances from air or other gas containing them. The particular filter shown is designed for a flow rate of 1000 cubic feet per minute and has a height of about 26" and a diameter of about 20". Although the filter is shown in a vertical position in the drawings, it is to be understood that it can be used in any desired orientation and has been designed with that requirement in mind.

As shown in Figure 1, the filter has an outer perforated cylindrical casing 10 which is preferably made of stainless steel having regard to the stringent conditions under which the filter will be used. Within this outer casing is another perforated casing 12 of the same material with the upper and lower ends of the two casings being brought together as shown at 14 in Figure 2. The lower end 14 of the double casing thus formed is securely attached by welding and/or rivetting to a stainless steel forging 16 forming one end of the filter. As will be seen from Figure 2, the forging 16 is provided with a number of projecting hooks or studs 18~preferably three arranged at 1200 intervals-which can be gripped by mechanical hands or other handling equipment in order to position the filter in a duct or other holder when it is installed for use.

The other end of the filter is closed by a stainless steel lid or cap 20 which is likewise welded and/or rivetted to the upper end 14 of the double casing 10, 12. By way of example, the gap between the two casings 10 and 12 can be of the order of a few millimetres.

Within the casing 12 there is an annular mesh 22 of finely woven metal strands, the mesh 22 preferably being in face to face contact with the casing 12. Concentrally arranged within the mesh 22 and spaced away from it as shown in Figure 3 is a further annular mesh 24 which is supported by an intermediate perforated casing 26 of the same material as the casings 10 and 12. An annular space 28 is thus formed between the two meshes 22 and 24, which space extends from top to bottom of the filter. Along the outer perimeter of this space-and in contact with the outer mesh 22-is an annular layer 30 of cellular material which is shown in perspective view in Figure 4. This cellular material is made of aluminium and is produced by bending a flat sheet of aluminium honeycomb material into a cylindrical shape and then joining its abutting ends.It is to be noted that this annular layer 30 occupies only the outer peripheral portion of the space 28 so that there is an ample annular gap formed between the inner surface of the layer 30 and the mesh 24.

The whole of the space 28 is tightly packed with activated carbon granules or particles, the full packing of the space being ensured by vibrating the bed of carbon material as it is poured into the space 28. As a result, the granules or particles of activated carbon are packed into all the cells of the cellular layer 30 and occupy all the remainder of the space 28 between the cellular layer 30 and the inner mesh 24.

In order that the carbon particles or granules may remove iodine compounds from air or other gas passed through the filter, the carbon is impregnated with triethylene diamine which reacts with methyl iodide and other iodine compounds so as to remove them from the air or gas. For best results, the triethylene diamine is applied in a 5% w/w solution. It is to be understood however that other impregnating agents can be used instead or in addition to triethylene diamine so as to remove specific noxious substances from the air or gas to be filtered.

Within the intermediate casing 26 and spaced a few millimetres from it is another intermediate casing 32 of the same construction. This forms the outer casing of a filter element which uses pleated filtering paper 34 as a filtering medium. As will be seen from Figure 3, the pleated filtering paper 34 forms an annular filtering medium with the inner crests of the pleats being bounded by an inner cylindrical casing 36 of the same material as the casings 10, 12, 26 and 32. As shown in Figure 2, the pleated filtering paper 34 extends from top to bottom of the filter.

The lower end of the inner perforated casing 36 is joined to the forging 16 at 38, the forging being provided with an inlet or outlet 40 for the entry or exhaust of air or gas into or from the filter. Air or other gas accordingly flows radially through the two above-mentioned filtering media-one after the other from outside the casing 10 to the space within the inner casing 36 or vice versa. All air or other gas passing through the filter is therefore made to pass through the activated carbon in the compartment or space 28 and through the filtering paper 34.

In order to prevent any leakage of fluid round the filtering media at either end of the filter, the ends of the casings 10, 12, 26, 32 and 36, as well as the ends of the cellular layer 30, the meshes 22 and 24 and the pleated filtering paper 34 are all embedded in upper and lower layers 42 of a synthetic plastics material which is moulded on to those ends. This is preferably done by placing one end of the filter lowermost on a horizontal surface during manufacture of the filter and pouring in the molten or liquid synthetic plastics material so that it sets hard with one end of each of the above-mentioned components embedded in it. The whole filter is then turned upside down and the process is repeated by pouring in more synthetic plastics material in molten or liquid form so as to seal the other ends of the said components. There are several synthetic plastics which can be used, but it has been found that a urethane-based compound is particularly satisfactory for this purpose.

Claims

1. A fluid filter comprising an annular compartment containing activated carbon granules or particles and, on the inside or outside of that compartment, a high-efficiency filter element so that air or other gas to be filtered as made to pass through the said two filtering media in succession, there being an annular cellular layer arranged along the outer perimeter of the compartment containing the activated carbon granules or particles with the cells of the cellular layer and the space between the cellular layer and the inner perimeter of the said compartment being packed tightly with the activated carbon granules or particles.

2. A fluid filter according to claim 1 having an outer perforated casing of generally cylindrical shape.

3. A fluid filter according to claim 2, in which the outer casing is made of stainless steel.

4. A fluid filter according to claim 2 or claim 3, in which a further perforated casing of the same material as the outer casing is arranged within the latter with the upper and lower ends of the two casings being brought together.

5. A fluid filter according to claim 4, in which one end of the double casing formed by the inner and outer casings is securely attached by welding and/or rivetting to a forging forming one end of the filter.

6. A fluid filter according to claim 5, in which the forging is provided with a number of projecting hooks or studs which can be gripped by mechanical hands or other handling equipment in order to position the filter in a duct or other holder.

7. A fluid filter according to claim 5 or claim 6, in which the other end of the double casing formed by the inner and outer casings is closed by a lid or cap which is welded and/or rivetted to the double casing.

8. A fluid filter according to claim 4 or any claim appendant thereto, in which an annular mesh of finely woven metal strands is arranged within the inner casing.

9. A fluid filter according to claim 8, in which a further annular mesh is arranged concentrically within the first-mentioned annular mesh so as to be spaced away from it, the further annular mesh being supported by an intermediate perforated casing.

10. A fluid filter according to claim 8 or claim 9, in which the annular cellular layer lies in contact with the first-mentioned annular mesh.

11. A fluid filter according to any preceding claim, in which the annular cellular mesh is made of aluminium.

12. A fluid filter according to claim 11, in which the annular cellular layer is produced by bending a flat sheet of aluminium honeycomb material into a cylindrical shape and then joining its abutting ends.

13. A fluid filter according to any preceding claim, in which the carbon granules or paricles are impregnated with triethylene diamine so as to react with methyl iodide and other iodine compounds which may be contained in the air or gas to be filtered by the filter.

14. A fluid filter according to claim 9 or any claim appendant thereto, in which a further intermediate casing of the same construction as the first intermediate casing is arranged within the latter but spaced from it, the further intermediate casing forming the outer casing of a filter element having a pleated filtering medium.

15. A fluid filter according to any preceding claim, in which the ends of the filter comprise layers of a synthetic plastics material serving as a sealing medium for the components of the filter, the said layers being applied in a liquid state once the components of the filter have been placed in position.

16. A fluid filter substantially as described herein with reference to the accompanying drawings.