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GB2109700A - Bed packing material - Google Patents

Bed packing material Download PDF

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Publication number
GB2109700A
GB2109700A GB08228241A GB8228241A GB2109700A GB 2109700 A GB2109700 A GB 2109700A GB 08228241 A GB08228241 A GB 08228241A GB 8228241 A GB8228241 A GB 8228241A GB 2109700 A GB2109700 A GB 2109700A
Authority
GB
United Kingdom
Prior art keywords
packing material
bed packing
inches
piece
polyolefin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08228241A
Inventor
Lowell E Huffman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of GB2109700A publication Critical patent/GB2109700A/en
Withdrawn legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D39/00Filtering material for liquid or gaseous fluids
    • B01D39/02Loose filtering material, e.g. loose fibres
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D39/00Filtering material for liquid or gaseous fluids
    • B01D39/02Loose filtering material, e.g. loose fibres
    • B01D39/04Organic material, e.g. cellulose, cotton
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D46/00Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/30Particle separators, e.g. dust precipitators, using loose filtering material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/30Loose or shaped packing elements, e.g. Raschig rings or Berl saddles, for pouring into the apparatus for mass or heat transfer
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/30Details relating to random packing elements
    • B01J2219/302Basic shape of the elements
    • B01J2219/30223Cylinder
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/30Details relating to random packing elements
    • B01J2219/302Basic shape of the elements
    • B01J2219/30276Sheet
    • B01J2219/30292Sheet rolled up
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/30Details relating to random packing elements
    • B01J2219/304Composition or microstructure of the elements
    • B01J2219/30466Plastics

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Organic Chemistry (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Filtering Materials (AREA)

Abstract

A bed packing material piece 3 for use in filtering a gas, such as compressed air, is a coiled cylindrically-shaped member, spiralled about a central longitudinal axis. The bed packing material piece 3 is made of a polyolefin whose molecular weight may be as low as 2.5 million. Where the gas to be filtered is compressed air, the polyolefin is preferably polyethylene. The bed packing material piece 3 does not compress in normal use, thus keeping the void volume open. Thus, both entrained solids and liquids, are entrapped, even if the liquids are dissimilar, such as oil and water. Individual pieces of bed packing material are made by cutting from a solid core. <IMAGE>

Description

SPECIFICATION Bed packing material This invention relates to a bed packing material for use in gas filtration, and to a method of making such a packing material.
In the purification of a gas, especially a compressed gas such as compressed air, particulate matter and liquids become entrained in the gas (or natural impurities which are in the gas prior to its being compressed) require the gas to be freed of these impurities before use. The types of entrained materials include oil droplets, water droplets, and solid particulates such as dust and carbon, all of which have different physical properties. The bed packing material, which is utilised in a filter, should be designed to remove all types of entrained materials, without allowing the filtation of the materials seriously to impede the void volume for gas flow through the bed packing.
The aim of the invention is to provide a bed packing material which, because of its physical make-up and configuration, has a high void volume, thus allowing unimpeded and rapid flow of a gas through a filter containing the bed packing material.
The present invention provides a piece of bed packing material for use in processes for separating liquids and solids from gases, the piece of bed packing material comprising an elongate member which has a length of from about 0.2 inches to about 1.0 inches, a width of from about 0.02 inches to about 0.25 inches, and a thickness of from about 0.001 inches to about 0.020 inches, the member being coiled about a central axis to form a multi-layered spiraled cylinder having more than one complete coil.
This bed packing material piece has a high surface-area-to-volume ratio, so that entrained material is easily trapped. Moreover, this bed packing material piece will hold both water and oil on its surface, without the normal mutual exclusivity of these two materials when they are present on the same surface. Furthermore, this bed packing material piece is free filling, and random alignment is all that is necessary for proper filling of the filter bed.
Advantageously, the member is made of a polyolefin having a molecular weight of at least 2.5 million. Preferably, the polyolefin has a molecular weight of about 4 million, and the pololefin is selected from the group consisting of polyethylene, polypropylene and polybutylene.
Alternatively, the member is made of a halogenated polyolefin having a molecular weight of at least 2.5 million. In this case, the halogenated polyolefin may be fluorinated.
Preferably, the bed packing material piece is sufficiently strong to support a column of similar bed packing material pieces which is at least twenty inches in height without appreciable compression.
Another advantage of the invention is that the packing material is relatively stiff and does not compress upon itself, which would reduce the void volume and the flow of air or other gases through it.
The invention also provides a method of making pieces of bed packing material, the method comprising the steps of rotatably mounting a solid cylindrical member of polyolefin or halogenated polyolefin about its central longitudinal axis, cutting longitudinal grooves into the cylindrical surface member, using a sharp instrument, so that the distance between adjacent grooves is from about 0.2 inches to about 1.0 inches, and rotating the solid cylindrical member about its central axis whilst applying a cutting tool tangentially to the cylindrical surface of the member.
Advantageously, the cutting tool is placed at an angle and depth to shear off pieces of material whose width and thickness comply with the dimensional requirements defined above.
The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which:~ Fig. 1 is a perspective view of a single piece of the bed packing material of the invention, the piece of material being stretched out to its full length; Fig. 2 is a side elevation of a single piece of bed packing material constructed in accordance with the invention; Fig. 3 is a schematic plan view of the piece of bed packing material of Fig. 2; Fig. 4 is a perspective view of the piece of bed packing material of Figs. 2 and 3; and Fig. 5 is a perspective view showing the method of making pieces of bed packing material.
Referring to the drawings, Fig. 4 shows a single piece 3 of bed packing material, which is of a coiled, cylindrical configuration. As shown best in Fig. 3, there is a large void space within the piece 3 as it spirals round a central longitudinal axis 2.
Fig. 1 shows the piece of bed packing material in a flattened, stretched-out state 1. In this state 1, the piece has a length L of between about 0.2 inches and about 1.0 inches, a width W of between about 0.02 inches and about 0.25 inches, and a depth D of between about 0.001 inches and about 0.020 inches.
Although the drawings indicate that the piece 3 of bed packing material is a perfect cylinder with a flat top, a flat base and a perfect spiral, it will be apparent that, in the manufacture of the bed packing material piece, the spiral might not be so uniform, and one of the inner coils of the piece of bed packing material might protrude beyond the outer layer. Moreover, the piece of bed packing material could be made by spiraling a tetragon of different configuration than that shown in Fig. 1.
Obviously, in use, a large number of pieces 3 of bed packing material are stacked together to form a filter bed.
The substance used to make the bed packing material is an important consideration. The substance must be sufficiently stiff so that it will not compress, and so lose the all-important high void volume of the packing. Moreover, the material must be chemically resistant to all types of gases, as well as entrained materials which are present in the gases to be filtered.
Thus, polyolefins (which in themselves are inert and are chemically resistant to many materials) and halogenated polyolefins are considered to be the most desirable substances for the bed packing material. One of the substances which has been found to be extremely useful in the filtration of compressed air, after it has gone through a compressor, is polyethylene. The polyethylene and, in fact, all of the polyolefins described should have a molecular weight greater than 2.5 million.
Use of lower molecular weight materials results in either an inability to form the coils, or the formation of coils that do not retain their distinct identity and structural integrity. Polyolefins with a molecular weight of 4.5 million and greater will function properly. Only cost considerations would militate against the use of polyolefins having molecular weights of 4.5 million and above. The preferred range of molecular weight for polyethylene is 3.5 to 4 million. The preferred materials of construction are polyethylene and/or polypropylene.
The preferred form of bed packing material piece 3 shown in the drawings has the following dimensions: L = 0.5 inches, W = 0.05 inches and D = 0.0015 inches.
Moreover, as shown in Fig. 3, the number of parallel coiled surfaces is preferably at least two.
However, the coiled cylinder must always have more than one complete spiral about the central axis 2. The packing coils are tightly wound, leaving a a large cylindrical void, and facilitating retention of adsorbed impurities between the overlapping layers. The ratio of L to W should never be less than 3 to 1, and preferably is 10:1. This preferred form is especially good when the bed packing material is used to filter compressed air. Naturally, depending on the viscosity and flow factors of other gases (such as nitrogen, oxygen, helium and hydrogen chloride) for which this packing can be used, the preferred configuration will vary, as will the preferred material of construction. The preferred material of construction indicated above for compressed gas filtration is polyethylene with a molecular weight of about 4 million.The coiled shape of the packing material is critical, since this shape, and the provision of overlapping coiled layers, enables the packing material to spread entrapped fluids such as water and oil between the layers, and thus keep them separate from the flowing gases. The surface area, and the resulting high surface tension of the film which forms between the layers, prevents re-entrainment in the gas stream of the removed liquids. Naturally, the flexibility of the thin coils is also important, and the flexibility of the materials of construction listed above is a necessary ingredient for obtaining a good bed packing material for use in filtration of compressed gases.The bed packing material of this invention will not show any appreciable compression when supporting a column of 20 inches of bed packing, that is to say, the lowest bed packing piece 3 of a filter bed will retain its shape under 20 inches of bed packing.
A method of making the pieces 3 of bed packing material is shown schematically in Fig. 5.
There, a solid cylinder 4 of the polyolefin from which the pieces 3 are to be made is scored to within an inch or two of its central axis. The solid cylinder 4 scored in this manner is placed on a lathe or other rotating apparatus. A cutting tool 5, such as a chisel or a knife, is then pressed against the solid cylinder 4 with sufficient force so that it penetrates the solid scored cylinder. The cylinder 4 is then rotated, causing the cutting tool 5 to remove a thin strip of the polyolefin material. This strip is interrupted by the scorings on the solid cylinder 4. Thus, a large number of hollow coiled cylinders which are the pieces 3 of bed packing material, can be manufactured from each solid cylinder 4. Naturally, the smaller the diameter of the solid cylinder 4, the shorter are the resulting pieces 3 of bed packing material, that is to say the dimension L is reduced. In order to avoid having pieces of bed packing material which are too short, the core should not be scored any deeper than would result in pieces of bed packing material of less than 0.2 inches in length. A variety of lengths of the pieces of bed packing material which are used in a given filter bed is advantageous, as this will aid in maintaining a proper void space.

Claims (11)

1. A piece of bed packing material for use in processes for separating liquids and solids from gases, the piece of bed packing material comprising an elongate member which has a length of from about 0.2 inches to about 1.0 inches, a width of from about 0.02 inches to about 0.25 inches, and a thickness of from about 0.001 inches to about 0.020 inches, the member being coiled about a central axis to form a multi-layered spiraled cylinder having more than one complete coil.
2. A bed packing material piece as claimed in claim 1, wherein the member is made of a polyolefin having a molecular weight of at least 2.5 million.
3. A bed packing material piece as claimed in claim 2, wherein the polyolefin has a molecular weight of about 4 million.
4. A bed packing material piece as claimed in claim 2 or claim 3, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene and polybutylene.
5. A bed packing material piece as claimed in claim 1, wherein the member is made of a halogenated polyolefin having a molecular weight of at least 2.5 million.
6. A bed packing material piece as claimed in claim 5, wherein the halogenated polyolefin is fluorinated.
7. A bed packing material piece as claimed in any one of claims 1 to 6, wherein the bed packing material piece is sufficiently strong to support a column of similar bed packing material pieces which is at least twenty inches in height without appreciable compression.
8. A bed packing material piece substantially as hereinbefore described with reference to, and as illustrated by, Figs. 1 to 4, of the accompanying drawings.
9. A method of making pieces of bed packing material, the method comprising the steps of rotatably mounting a solid cylindrical member of polyolefin or halogenated polyolefin about its central longitudinal axis, cutting longitudinal grooves into the cylindrical surface member, using a sharp instrument, so that the distance between adjacent grooves is from about 0.2 inches to about 1.0 inches, and rotating the solid cylindrical member about its central axis whilst applying a cutting tool tangentially to the cylindrical surface of the member.
10. A method as claimed in claim 9, wherein the cutting tool is placed at an angle and depth to shear off pieces of material whose width and thickness comply with the dimensional requirements of claim 1.
11. A method of making pieces of bed packing material substantially as hereinbefore described with reference to Fig. 5 of the accompanying drawings.
GB08228241A 1981-10-08 1982-10-04 Bed packing material Withdrawn GB2109700A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US30960281A 1981-10-08 1981-10-08

Publications (1)

Publication Number Publication Date
GB2109700A true GB2109700A (en) 1983-06-08

Family

ID=23198889

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08228241A Withdrawn GB2109700A (en) 1981-10-08 1982-10-04 Bed packing material

Country Status (1)

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GB (1) GB2109700A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4032234A1 (en) * 1990-10-11 1992-04-16 Kottwitz Max Anton Dipl Ing Di Gas purifying filter device - with filter bed contg. support bodies to prevent settling
EP0774290A1 (en) * 1995-11-20 1997-05-21 North Star Technologies Ltd. Separation apparatus and process
US5935300A (en) * 1996-11-19 1999-08-10 North Star Technologies Ltd Separation Apparatus
EP0857508B1 (en) * 1997-02-10 2004-01-02 Veritech Filtration Limited Separation apparatus

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4032234A1 (en) * 1990-10-11 1992-04-16 Kottwitz Max Anton Dipl Ing Di Gas purifying filter device - with filter bed contg. support bodies to prevent settling
EP0774290A1 (en) * 1995-11-20 1997-05-21 North Star Technologies Ltd. Separation apparatus and process
US5904751A (en) * 1995-11-20 1999-05-18 North Star Technologies Ltd. Separation apparatus
US5935300A (en) * 1996-11-19 1999-08-10 North Star Technologies Ltd Separation Apparatus
EP0857508B1 (en) * 1997-02-10 2004-01-02 Veritech Filtration Limited Separation apparatus

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)