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Upgrading water treatment plants
N e w I n v e n t i o n s in Filtration and S e p a r a t i o n ABSTRACTS British Patent Specifications
Modular air filter In BP 2206294. Heinz Holter describes a modular filter for extracting dust from air in a mine or tunnel. It consists of several housing parts and ends. which enable a filter of varying air flows to be constructed. The housing parts provide two channels, one for dirty air and the other for filtered air and these are located alongside one another at the top of the filter. One of these channels opens downwards into chambers housing removable filter bags, the mouths of which open into spaces leading to the 'clean air channels. A scraper fitted to the floor of the filter removes dust to an outlet from which it is drawn by a stream of water and air through an injector, after which it is fed to a cyclone to produce wet dust. (3 figs., 2,500words.)
Paper/carbon filter In BP 2206295, D A G Marshall describes a combined high efficiency pleated paper filter and an activated carbon filter. The two filters are arranged in a tubular casing provided with spigots which are formed by two rings attached to the end faces of the casing and arranged to be received in a passage of circular section such as the inlet or outlet of a fan casing. Flat annular flexible seals are fitted in the rings and make a sealing
Upgrading water treatment plants With UK water authorities planning to invest heavily over the next few years in replacing and uprating their water and effluent filtration facilities, Munters has high expectations that its biological filter medium utilising BIodek "~ will find wide a p p l i c a t i o n in trickling filters. Biodek", which was de-
444
OF BRITISH
PATENTS
can be ordered from Patents Office, Orpington,
contact with the passage walls. Another filter element of two-ply polyurethane foam may also be incorporated in one or both of these rings. (3 figs, 2,000words.)
Removing metal particles In BP 2207612. Max Stricker describes a labyrinth filter for removing very small metal particles produced in the dielectric liquid of a spark erosion apparatus. Liquid is passed downwards through a tall narrow bed of loosely packed sand in a closed housing. An upstream pump and the dimensions of the bed ensure that the downward flow exceeds 2m/min through the interstices of the bed, and this speed of opertion ensures that particles are trapped within the bed. Two beds may operate in series and are backwashed in turn. (10 figs.,
6,000words.)
ICE coolant filter In BP 2208068, Coopers AP Filters Ltd describes a filter assembly especially suited for use in automotive engine coolant fluids. It is designed to prevent fluid toss when being attached to the vehicle and detached for inspection. A mounting incorporates a valve which becomes operable when the filter is removed and prevents fluid loss. This mounting consists of a part
veloped in Sweden in the early '70s, is a s e l f - s u p p o r t i n g crossflow device fabricated from rigid pvc sheets with specially designed corruga t i o n s a n g l e d at 6 0 d o g . Standard m o d u l e s are 1.2m long and 0.6m high and wide. They are p r o d u c e d in Germany and fabricated locally. The m e d i u m is said to offer a greater surface area per v o l u m e of fluid than r a n d o m type media, p r o v i d e a longer retention time, with no fluid
Kent BR5 3RD, England
which partially unscrews from the main body as the filter is unscrewed from the boss and thereby allows a poppet valve to close the feed passage. The outlet passage incorporates a spring-loaded ball valve which closes automatically when the flow of fluid ceases. (2 figs., 2000 words.)
Self-cleaning filter In BP 2208206, Combustion Engineering Europe describes a selfcleaning filter for continuously removing solids from a liquid flowing through a channel. It consists of an endless filter belt entrained about shafts. Stripping paddles fitted above a discharge chute clean the filter belt. A jet spraying pipe extends parallel with the shafts, with the nozzles being directed towards the upper end of the chute. Effective cleaning of the discharge chute is further facilitated by the periodic washing from the nozzles.
(3 figs., 2,000words.)
Microfilter with variable pore size In BP2208611, Pennwalt Piezo Film Ltd describes a microfilter in which the effective pore size is selectively controllable. It consists of two films of polyvinylidene fluoride in face-to-face relationship and formed in a central being short-circuited, and avoid c l o g g i n g due to a void ratio of up to95%. It is suitable for both high and low rate filtration, and for new plants as well as upgrading existing ones. Overall costs per unit area are reckoned to be 70% or so of rock or lava filling or other plastic media. Munters forecast a d o u b l i n g of d e m a n d in the UK over the next two or three years for sewage plant equipment, and the c o m p a n y plans to install pilot plants at the various water boards, utilising the k n o w l e d g e gained from the 500 plants it has been involved with world-wide. Some £5m a year is currently being spent on media conversions in the UK, w h i c h it is felt will increase to a r o u n d £12m in two or three years' time. North West Water are said to be s p e n d i n g £1m on nitrification trials so that the new a m m o n i a consent levels can be achieved.
Munters Ltd, Blackstone Road, Huntingdon, CambsPE186EF.
portion with aligned apertures of between 10and 13p. Each of the two films has electrodes on each face of either side of the central portion. The application of varying voltages to the electrodes produces a relative lateral movement of the central portion of the films which varies the effective pore size by moving the pores out of register. The relative movement is assisted by a silicone oil lubricant between the films. (4 figs., 2,000words.)
Suction dewatering In BP 2209128. Delkor Ltd describes filtering equipment especially suitable for the filtering of liquid based slurries. The equipment has an endless filter cloth which passes under a slurry feed and over a suction box where suction is applied to the cloth to remove liquid from the slurry. The cloth is entrained round a roller and the suction on the cloth is relieved intermittently by a motor. A central controller adjusts the length of advance of the cloth at each movement. (4 figs., 5,000words.)
Forming a filter medium In BP 2209354, Tsuchlya Mfg Co Ltd describes a system and process for forming a filter medium. Pleats of the filter extend radially outward, the sides of the pleats being alternatively bonded at the inner and outer peripheral sides to allow a fluid to be filtered to flow generally along the lines of the pleats. Two scoring drums form linear depressions on the opposite side surfaces of an elongate sheet type filter medium. Adhesive is then applied on the opposite side surfaces at the edge sections. Pleats are formed on the medium along the depression each having two sides contiguous through each linear depression. The system is suitable for mass production at high speeds with great accuracy. (34 figs., 12000 words.)
Deep fry oil filter In BP2209684. VA Whitney& Co Ltd describes a filter for use in high frying and similar ranges. A deep fry oil filter consists of a handle and a pair of shallow mesh baskets which hinge or clip together to enclose a filter cloth or paper between them. The device can be used without the filter cloth or paper when lifting food from the oil. Baskets can be rectangular in cross section, wedge shaped or truncated wedge shaped, or circular.
(2 figs., t.O00words.)
November/December 1990
Filtration & Separation
Modular air filter In BP 2206294. Heinz Holter describes a modular filter for extracting dust from air in a mine or tunnel. It consists of several housing parts and ends. which enable a filter of varying air flows to be constructed. The housing parts provide two channels, one for dirty air and the other for filtered air and these are located alongside one another at the top of the filter. One of these channels opens downwards into chambers housing removable filter bags, the mouths of which open into spaces leading to the 'clean air channels. A scraper fitted to the floor of the filter removes dust to an outlet from which it is drawn by a stream of water and air through an injector, after which it is fed to a cyclone to produce wet dust. (3 figs., 2,500words.)
Paper/carbon filter In BP 2206295, D A G Marshall describes a combined high efficiency pleated paper filter and an activated carbon filter. The two filters are arranged in a tubular casing provided with spigots which are formed by two rings attached to the end faces of the casing and arranged to be received in a passage of circular section such as the inlet or outlet of a fan casing. Flat annular flexible seals are fitted in the rings and make a sealing
Upgrading water treatment plants With UK water authorities planning to invest heavily over the next few years in replacing and uprating their water and effluent filtration facilities, Munters has high expectations that its biological filter medium utilising BIodek "~ will find wide a p p l i c a t i o n in trickling filters. Biodek", which was de-
444
OF BRITISH
PATENTS
can be ordered from Patents Office, Orpington,
contact with the passage walls. Another filter element of two-ply polyurethane foam may also be incorporated in one or both of these rings. (3 figs, 2,000words.)
Removing metal particles In BP 2207612. Max Stricker describes a labyrinth filter for removing very small metal particles produced in the dielectric liquid of a spark erosion apparatus. Liquid is passed downwards through a tall narrow bed of loosely packed sand in a closed housing. An upstream pump and the dimensions of the bed ensure that the downward flow exceeds 2m/min through the interstices of the bed, and this speed of opertion ensures that particles are trapped within the bed. Two beds may operate in series and are backwashed in turn. (10 figs.,
6,000words.)
ICE coolant filter In BP 2208068, Coopers AP Filters Ltd describes a filter assembly especially suited for use in automotive engine coolant fluids. It is designed to prevent fluid toss when being attached to the vehicle and detached for inspection. A mounting incorporates a valve which becomes operable when the filter is removed and prevents fluid loss. This mounting consists of a part
veloped in Sweden in the early '70s, is a s e l f - s u p p o r t i n g crossflow device fabricated from rigid pvc sheets with specially designed corruga t i o n s a n g l e d at 6 0 d o g . Standard m o d u l e s are 1.2m long and 0.6m high and wide. They are p r o d u c e d in Germany and fabricated locally. The m e d i u m is said to offer a greater surface area per v o l u m e of fluid than r a n d o m type media, p r o v i d e a longer retention time, with no fluid
Kent BR5 3RD, England
which partially unscrews from the main body as the filter is unscrewed from the boss and thereby allows a poppet valve to close the feed passage. The outlet passage incorporates a spring-loaded ball valve which closes automatically when the flow of fluid ceases. (2 figs., 2000 words.)
Self-cleaning filter In BP 2208206, Combustion Engineering Europe describes a selfcleaning filter for continuously removing solids from a liquid flowing through a channel. It consists of an endless filter belt entrained about shafts. Stripping paddles fitted above a discharge chute clean the filter belt. A jet spraying pipe extends parallel with the shafts, with the nozzles being directed towards the upper end of the chute. Effective cleaning of the discharge chute is further facilitated by the periodic washing from the nozzles.
(3 figs., 2,000words.)
Microfilter with variable pore size In BP2208611, Pennwalt Piezo Film Ltd describes a microfilter in which the effective pore size is selectively controllable. It consists of two films of polyvinylidene fluoride in face-to-face relationship and formed in a central being short-circuited, and avoid c l o g g i n g due to a void ratio of up to95%. It is suitable for both high and low rate filtration, and for new plants as well as upgrading existing ones. Overall costs per unit area are reckoned to be 70% or so of rock or lava filling or other plastic media. Munters forecast a d o u b l i n g of d e m a n d in the UK over the next two or three years for sewage plant equipment, and the c o m p a n y plans to install pilot plants at the various water boards, utilising the k n o w l e d g e gained from the 500 plants it has been involved with world-wide. Some £5m a year is currently being spent on media conversions in the UK, w h i c h it is felt will increase to a r o u n d £12m in two or three years' time. North West Water are said to be s p e n d i n g £1m on nitrification trials so that the new a m m o n i a consent levels can be achieved.
Munters Ltd, Blackstone Road, Huntingdon, CambsPE186EF.
portion with aligned apertures of between 10and 13p. Each of the two films has electrodes on each face of either side of the central portion. The application of varying voltages to the electrodes produces a relative lateral movement of the central portion of the films which varies the effective pore size by moving the pores out of register. The relative movement is assisted by a silicone oil lubricant between the films. (4 figs., 2,000words.)
Suction dewatering In BP 2209128. Delkor Ltd describes filtering equipment especially suitable for the filtering of liquid based slurries. The equipment has an endless filter cloth which passes under a slurry feed and over a suction box where suction is applied to the cloth to remove liquid from the slurry. The cloth is entrained round a roller and the suction on the cloth is relieved intermittently by a motor. A central controller adjusts the length of advance of the cloth at each movement. (4 figs., 5,000words.)
Forming a filter medium In BP 2209354, Tsuchlya Mfg Co Ltd describes a system and process for forming a filter medium. Pleats of the filter extend radially outward, the sides of the pleats being alternatively bonded at the inner and outer peripheral sides to allow a fluid to be filtered to flow generally along the lines of the pleats. Two scoring drums form linear depressions on the opposite side surfaces of an elongate sheet type filter medium. Adhesive is then applied on the opposite side surfaces at the edge sections. Pleats are formed on the medium along the depression each having two sides contiguous through each linear depression. The system is suitable for mass production at high speeds with great accuracy. (34 figs., 12000 words.)
Deep fry oil filter In BP2209684. VA Whitney& Co Ltd describes a filter for use in high frying and similar ranges. A deep fry oil filter consists of a handle and a pair of shallow mesh baskets which hinge or clip together to enclose a filter cloth or paper between them. The device can be used without the filter cloth or paper when lifting food from the oil. Baskets can be rectangular in cross section, wedge shaped or truncated wedge shaped, or circular.
(2 figs., t.O00words.)
November/December 1990
Filtration & Separation