GB2303563A - Self-cleaning liquid screening apparatus with level sensor - Google Patents

Self-cleaning liquid screening apparatus with level sensor Download PDF

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Publication number
GB2303563A
GB2303563A GB9515431A GB9515431A GB2303563A GB 2303563 A GB2303563 A GB 2303563A GB 9515431 A GB9515431 A GB 9515431A GB 9515431 A GB9515431 A GB 9515431A GB 2303563 A GB2303563 A GB 2303563A
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GB
United Kingdom
Prior art keywords
drum
chamber
screening apparatus
screening
level
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.)
Granted
Application number
GB9515431A
Other versions
GB9515431D0 (en
GB2303563B (en
Inventor
Leonard Harris
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Individual
Original Assignee
Individual
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Filing date
Publication date
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Application filed by Individual filed Critical Individual
Priority to GB9515431A priority Critical patent/GB2303563B/en
Publication of GB9515431D0 publication Critical patent/GB9515431D0/en
Publication of GB2303563A publication Critical patent/GB2303563A/en
Application granted granted Critical
Publication of GB2303563B publication Critical patent/GB2303563B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
    • B01D29/114—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements arranged for inward flow filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/60—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor integrally combined with devices for controlling the filtration
    • B01D29/605—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor integrally combined with devices for controlling the filtration by level measuring
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/62—Regenerating the filter material in the filter
    • B01D29/66—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
    • B01D29/68—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles
    • B01D29/682—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles with a rotary movement with respect to the filtering element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/62—Regenerating the filter material in the filter
    • B01D29/66—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
    • B01D29/68—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles
    • B01D29/688—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles with backwash arms or shoes acting on the cake side
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/62—Regenerating the filter material in the filter
    • B01D29/70—Regenerating the filter material in the filter by forces created by movement of the filter element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2201/00—Details relating to filtering apparatus
    • B01D2201/28—Position of the filtering element
    • B01D2201/282—Filtering elements with a horizontal rotation or symmetry axis

Abstract

A drum chamber 10 has a liquid inlet 44 for water containing solid waste. A rotatable screening drum 12 is mounted in the chamber with a substantially horizontal axis, to allow inward filtration. The drum is stationary while filtration occurs. The side wall of the drum 12 is formed by screening mesh 20 supported on external axial bars 22. One end of the drum is sealed against a side wall 26 of the chamber containing an opening 28 to form a weir that determines the level of filtered liquid in the drum. The chamber contains a level sensor 42 that operates the motor 16, to cause rotation of the drum when the liquid in the chamber rises to a certain level indicating clogging of the screen, thus causing a backwash that removes, through outlet 40, collected solid waste from the outside of the drum. A low level sensor in the chamber signals rotation to cease after at least one complete turn.

Description

SCREENING APPARATUS TECHNICAL FIELD OF THE INVENTION This invention relates to screening apparatus for removing solid matter from liquids.
BACKGROUND In the food processing, paper, chemical and sewage treatment industries for example, it is often necessary to screen (filter) extraneous solid matter from water, e.g. before the water can be discharged into a stream or river.
GB 991 875 discloses a high-pressure strainer in which a screening drum is mounted on a vertical shaft. Water is filtered through the screen, under pressure, to deposit solids on the outside of the drum. The solids are periodically removed through a vertical shoe having an outlet which is opened to permit a back-flow through the screen as the drum is rotated.
Such pressure strainers have a number of inherent disadvantages. Firstly, they are required to comply with strict codes of practice relating to pressure vessels, making their construction and maintenance very costly. In addition, the arrangement of the drum means that the only effective way of sensing when the drum requires cleaning is by monitoring the pressure differential across the drum. However, such an arrangement would not operate effectively at low pressures. Furthermore, a high pressure differential is essential to ensure efficient cleaning of the upper part of the vessel, where hydrostatic head alone would be insufficient for effective cleaning. Lastly, solids inevitably tend to settle at the bottom of the drum chamber, leading to inefficient screening and risk of blockages if drum chamber is not cleaned out regularly.
An aim of the present invention may be viewed as being to provide a form of screening drum which is inexpensive to build and operate, requires only infrequent maintenance, and has low energy consumption.
SUMMARY OF THE INVENTION The present invention proposes a low pressure liquid screening apparatus comprising: - a drum chamber having a liquid inlet; - a screening drum mounted in the chamber for rotation about a substantially horizontal axis, one end of the drum being sealed against a wall of the chamber which contains an opening forming a weir which determines the liquid level in the drum; - drive means for rotating the drum; - a port shoe disposed adjacent to the outer surface of the drum and having a back wash outlet; and - level sensing means arranged to operate the drive means to rotate the drum when the liquid level in the drum chamber rises to a predetermined level.
BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is a general view of screening apparatus in accordance with the invention, shown partly cut-away to reveal the internal construction.
DETAILED DESCRIPTION OF THE DRAWINGS The illustrated screening drum comprises a main drum chamber 10, which may be open to atmosphere at the top as shown, containing a screening drum 12. The drum is mounted horizontally on a shaft 14, which is driven for rotation by an electric or similar motor 16 via suitable reduction drive gear 18.
The drum 1 2 is preferably formed of stainless steel, as is the drum chamber 10. The cylindrical side wall of the drum is formed of circumferentially disposed wedge wire or micro mesh 20 supported and reinforced by external axial bars 22. One end of the drum has an end wall 24 which is fixed with the shaft 14, whilst the opposite end of the drum is open, being applied against a side wall 26 of the drum chamber via a low pressure V-seal (not shown). The shaft 14 passes through the open end of the drum, extending through the wall 26 to connect with the drive gear 18. The wall 26 contains an opening 28 which leads from the inside of the drum to an outlet 32 via an exit chamber 34, also open to atmosphere. The opening 28 has a horizontal bottom edge 36, just below the level of the shaft 14, creating a weir which determines the water level in the drum.
A port shoe 38 is coupled to a backwash outlet 40 which passas out of the main drum chamber 10 via a normally closed backwash valve (not shown).
The shoe contains a lateral slot-shaped opening which is closely applied to the outside of the drum, towards the bottom of the drum, extending across substantially the entire axial width of the drum.
The chamber 10 contains a float-operated or other level sensing switch 42.
Dirty water containing solid waste material enters the main drum chamber 10 via an inlet 44. As the water level rises in the chamber the water passes through the mesh 20 into the drum depositing solid matter on the outside of the drum. The bars 22 tend to assist in trapping the solids on the surface of the mesh. Inside the drum the filtered water passes over the weir 36 and is conducted away via outlet 32. When the mesh is relatively unobstructed water continuously passes into the drum so that the water level in the chamber 10 will be substantially level with that in the drum 12, but when solids begin to blind the mesh the water level rises in the main drum chamber. When the level rises sufficiently, the switch 42 is actuated to switch on the motor 16 causing the drum to rotate and, at the same time, opening the backwash valve. The hydrostatic head of water in the drum 12 causes a reverse flow of water through the mesh, carrying the solids off the outside out of the drum, assisted by a flow of water into the shoe from the drum chamber 10. Such flow from the drum chamber also carries any settled solids into the shoe from the main drum chamber.
A conductivity probe or low level sensor (not shown) is included in the drum chamber to ensure that the drum undergoes at least one complete rotation before the drum stops and the backwash valve closes.
The apparatus is thus inexpensive to manufacture, requires little supervision, infrequent maintenance due to lack of wearing parts, and has a low energy consumption.

Claims (9)

1. Low pressure liquid screening apparatus comprising: - a drum chamber having a liquid inlet; - a screening drum mounted in the chamber for rotation about a substantially horizontal axis, one end of the drum being sealed against a wall of the chamber which contains an opening forming a weir which determines the liquid level in the drum; - drive means for rotating the drum; - a port shoe disposed adjacent to the outer surface of the drum and having a back wash outlet; and - level sensing means arranged to operate the drive means to rotate the drum when the liquid level in the drum chamber rises to a predetermined level.
2. Screening apparatus according to Claim 1, which comprises further sensing means arranged to ensure that drum undergoes at least one complete rotation whenever the drum is rotated in response to a rise in liquid level in the drum chamber.
3. Screening apparatus according to Claim 2, in which the further sensing means is located in the drum chamber.
4. Screening apparatus according to Claim 2 or 3, in which the further sensing means comprises a conductivity probe or low lXvvèl sensor.
5. Screening apparatus according to any precedirtg claim, in which the side wall of the drum comprises filter means supported by axial bars.
6. Screening apparatus according to Claim 6, in which said bars are disposed on the outside of the drum relative to the filter means.
7. Screening apparatus according to any preceding claim, in which the screening drum is formed of stainless steel.
8. Screening apparatus according to any preceding claim, in which the drum chamber is formed of stainless steel.
9. Low pressure liquid screening apparatus substantially as described with reference to the drawing.
9. Low pressure liquid screening apparatus substantially as described with reference to the drawing.
Amendments to the claims have been filed as follows CLAIMS 1. Low pressure liquid screening apparatus comprising: - a drum chamber having a liquid inlet; - a screening drum mounted in thuhamber for rotation about a substantially horizontal axis, one end of the drum being sealed against a wall of the chamber which contains an opening forming a weir which determines the liquid level in the drum; - drive means for rotating the drum; - a port shoe disposed adjacent to the outer surface of the drum and having an outlet for solids removed from the outside of the drum via the port shoe by means of a pressure differential between the drum chamber and said outlet; and - level sensing means arranged to operate the drive means to rotate the drum when the liquid level in the drum chamber rises to a predetermined level.
2. Screening apparatus according to Claim 1, which comprises further sensing means arranged to ensure that drum undergoes at least one complete rotation on each occasion when the drum is rotated in response to a rise in liquid level in the drum chamber.
3. Screening apparatus according to Claim 2, in which the further sensing means is located in the drum chamber.
4. Screening apparatus according to Claim 2 or 3, in which the further sensing means comprises a conductivit',' probe or low level sensor.
Screening apparatus according to any preceding claim, in which the side wall of the drum comprises filter means supported by axial bars.
6. Screening apparatus according to Claim 6, in which said bars are disposed on the outside of the drum relative to the filter means.
7. Screening apparatus according to any preceding claim, in which the screening drum is formed of stainless steel.
8. Screening apparatus according to any preceding claim, in which the drum chamber is formed of stainless steel.
GB9515431A 1995-07-27 1995-07-27 Screening apparatus Expired - Fee Related GB2303563B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9515431A GB2303563B (en) 1995-07-27 1995-07-27 Screening apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9515431A GB2303563B (en) 1995-07-27 1995-07-27 Screening apparatus

Publications (3)

Publication Number Publication Date
GB9515431D0 GB9515431D0 (en) 1995-09-27
GB2303563A true GB2303563A (en) 1997-02-26
GB2303563B GB2303563B (en) 1999-04-07

Family

ID=10778367

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9515431A Expired - Fee Related GB2303563B (en) 1995-07-27 1995-07-27 Screening apparatus

Country Status (1)

Country Link
GB (1) GB2303563B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2375972A (en) * 2001-06-02 2002-12-04 Brian Denis Waring Filter with automatic backwashing

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113931464A (en) * 2021-09-23 2022-01-14 中建八局第一建设有限公司 Structure outer wall continuously sprays maintenance and maintains water, rainwater recovery system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1357902A (en) * 1971-04-22 1974-06-26 Glenfield & Kennedy Ltd Liquid straining apparatus
WO1988001899A1 (en) * 1986-09-08 1988-03-24 Allsing Karl J A method in primarily so-called rotating filters, and a filter
WO1988007401A1 (en) * 1987-04-03 1988-10-06 Kemijoki Oy Self-operated drum filter and method for the filtration of water

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DK394888A (en) * 1988-07-14 1990-02-12 Tage Christoffer Hansen PROCEDURE TO CLEAN PARTICLES FROM A FILTER AND A FILTER FOR USE THEREOF

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1357902A (en) * 1971-04-22 1974-06-26 Glenfield & Kennedy Ltd Liquid straining apparatus
WO1988001899A1 (en) * 1986-09-08 1988-03-24 Allsing Karl J A method in primarily so-called rotating filters, and a filter
WO1988007401A1 (en) * 1987-04-03 1988-10-06 Kemijoki Oy Self-operated drum filter and method for the filtration of water

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2375972A (en) * 2001-06-02 2002-12-04 Brian Denis Waring Filter with automatic backwashing

Also Published As

Publication number Publication date
GB9515431D0 (en) 1995-09-27
GB2303563B (en) 1999-04-07

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19990727

728V Application for restoration filed (sect. 28/1977)
7282 Application for restoration refused (sect. 28/1977)