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Abstracts of British patents
New Inventions.in Filtration and Separation ". ABSTRACTS OF BRITISH PATENTS British Patent Specifications can be ordered from Patents Office, Orpington, Kent BR5 3RD, England
Separating CO 2 and methane
Centrifugal filter for fine materials
In BP 2184665, The BOC Group Ltd describes a method of separating gaseous mixtures, especially carbon dioxideandmethane, to form a product gaswith a reduced concentration of carbon dioxide. A gas mixture with up to 12% volume of carbon dioxide is subject to rectification in a first column to form a carbon dioxidedepleted fraction. A carbon dioxideenriched fraction is withdrawn from the bottomof the column, warmed in a heat exchanger, and introduced with a second rectification column operating at a higher pressure than the first column. A carbon dioxide depleted fraction as product is withdrawn from the top of the first column. A stream in which carbon dioxide predominates is withdrawn from the bottom of thesecond column while a stream containing a lower portion of carbon dioxide than the other enriched fraction is withdrawn from the top of the column'and is throttled through a valve and united with the stream upstream of that from the top of the column. A high yield of methaneis achieved. (5 figs., 6,000 words.)
In BP 2184667, Birtley Engineering Ltd describes a centrifugal filter especially for the dewatering of fine materials which require a relatively high centrifugal acceleration for the removal of thefree liquid phase. It consists of a centrifugal filter basket which is rotated and also subjected to axial vibrations which are produced by contra-rotary weights which cause relative axial vibration of a pusher plate mounted in the basket by rubber blocks to urge solids towards the open end of thebasket. Advantages claimed are ease of manufacture and maintenance, with lowwearcharacteristics. (1 fig., 2,000 words.)
Plasma thermofiltration In BP2184670, The Cleveland Clinic Foundation describes a method of filtration of macro molecules from fluids and more particularly the removal of undesirable macro molecules from plasma solutions moreselectively.
Plasma containing the macromolecules to beremoved is heated to a temperature nearor close to body temperature but below the boiling point of the plasma solution. The heated plasma solution is filtered at this temperature with a membrane filter to remove selectively macromolecules from the plasma solution. An apparatus to provide this process isdescribed. (6 figs., 12,000 words}
Two-phase liquidliquid extraction In BP 2184956, Kernforschungszentrum Karlsruhe GmbH describes a two-phase system for liquid-liquid extraction. It comprises anaqueous phase and an organic phase, one being the starting liquid where one or. more valuable materials are separated fromimpurities andfromoneanother in a multi-stage extraction apparatus. Valuable materials aretransferred by extraction from the starting liquid to the otherphase whichis washed with a washing liquid corresponding to thestarting liquid. Before being fed into the'extraction apparatus, the extractant phase is divided into at least two streams which are separately introduced at different points of the extraction apparatus ahead in their directionof flow.Theobjective of the invention is to improve the effectiveness of a liquid-liquid extraction process in a two-phase system where several valuable materials arepresent. Theinvention seeks to combine the advantages of the so-called concentrationflow scheme with thoseof the so-called flow dilute flow scheme. (6 figs., 6,000 words.)
Treating filter media
Automatic sampler TheSP3 autosampler hasbeen introduced by Paar Scientific to complement the DMA 48, microprocessor controlled, digital density meter. When linked, thetwo unitsaresaidto provide an automatic system for the accurate, fast measurement of density and specific gravity of liquids. gases andconcentrations of solids. The SP3 is suitable for use in qualitycontrolandotherlaboratories handling large quantities of samples each day, andcanbe left unattended for overnight sampling and linked to adataprocessor. Automatic measurement is carried out by a microprocessor controlled, menu-quided operation to minimise
60
cycle time.Asthesample is filled into the measuring cell by vacuum or pressure, viscous samples can also bemeasured automatically. A strong needle drive allows perforation of rubber sealed vials for measurement of toxic samples. and hasa speciafly designed sear to cover open vials. The samples are then transferred to the measuring cell by air/gas pressure. The SP3 has an automatic cycle for cleaning the sample feeding needle. Vials areoffered in a range of sizes from 10 to SOml and magazines are available whichholdfrom20up to 60 vials. Paar Scientific Ltd, 594 Kingston Road. Raynes Park. London SW20.
In BP 2185193, Labofina SA describes a method of treating spent filter media used in the clarification of liquid organic compounds, more particularly in recovering those organic compounds whichhave been sorbed in filter media. Filteraidsaremixed with aromatic solvents in two stages, the solvent from the first stage being distilledto separate out the additives; solvent is thenadded to thepartlycleaned filter aid in the second stage and wateris added before the two liquid and one solid phases areseparated by centrifuging. Thesolvent phase is then recycled to the first stage andthe waterto the second stage. (2 figs., 7.000 words.)
Lower cost duplex filter for mines In BP 2185418. DOlVty Mining Machinery Ltd describes a fluid filtering
system, in particular for use in the watersupply of mines. Two filtersare connected in parallel, the first being provided with a movable backflushing nozzle. Avalve normally directs flow through the first filter until rising flow necessitatesthe fluid being switched to the second filter while the first filter is backwashed. An element in the second filter is replaced periodically when dirty. The flow switching can be controlledautomatically byapressured drop monitor. Backwashing is effected by a nozzle which rotates as it is advanced axially inside anelement. Substantial savings in the cost of the system areclaimed because only one of the filter units needs be provided with means for backflushing. (4 figs. 5.000 wotds.)
Contaminants separated from gas In BP 2185422. David Victor Gent describes an apparatus for removing contaminants from a gas, suchasair found in industrial environments. It consists of a chamber with a gas inlet and outlet and a means for creating a curtain of washing liquid across the flow path of the gas between the two orifices. The curtain includes a rotatable imperforate disc and a nozzle located on one side of the disc and arranged coaxially thereto. The nozzle produces an emitted axial flow of liquid towards one side of the disc so as to contact the disc. The nozzle also causes the emitted flow of liquid to rotate aboutthe axis of the disc in thxsame direction as the rotation of the disc. (2 figs., 4,000 words.)
Coated filtering screens In BP2185698 Thule United Ltd describes improved filter screens, especially those for use in a vibrating screening apparatus used for screening drilling mud. The screen comprises a mesh with cores coated with a plastics material. Cores arepreferably of stainless steel or Kelvar. The plastics material, which should be abrasive resistant, may be applied to the mesh cores either before or after the cores are woven into themesh. Thickness of the coating is not criticaland may typically be between 2pm to 1mm. It may be applied by dip coating, solvent coating or spray coating. The properties of the screen, especially resistance to abrasion and adhesion, are improved by the coating process. (4 figs., 2,000 words.)
January/February 1989
Filtration & Separation
Separating CO 2 and methane
Centrifugal filter for fine materials
In BP 2184665, The BOC Group Ltd describes a method of separating gaseous mixtures, especially carbon dioxideandmethane, to form a product gaswith a reduced concentration of carbon dioxide. A gas mixture with up to 12% volume of carbon dioxide is subject to rectification in a first column to form a carbon dioxidedepleted fraction. A carbon dioxideenriched fraction is withdrawn from the bottomof the column, warmed in a heat exchanger, and introduced with a second rectification column operating at a higher pressure than the first column. A carbon dioxide depleted fraction as product is withdrawn from the top of the first column. A stream in which carbon dioxide predominates is withdrawn from the bottom of thesecond column while a stream containing a lower portion of carbon dioxide than the other enriched fraction is withdrawn from the top of the column'and is throttled through a valve and united with the stream upstream of that from the top of the column. A high yield of methaneis achieved. (5 figs., 6,000 words.)
In BP 2184667, Birtley Engineering Ltd describes a centrifugal filter especially for the dewatering of fine materials which require a relatively high centrifugal acceleration for the removal of thefree liquid phase. It consists of a centrifugal filter basket which is rotated and also subjected to axial vibrations which are produced by contra-rotary weights which cause relative axial vibration of a pusher plate mounted in the basket by rubber blocks to urge solids towards the open end of thebasket. Advantages claimed are ease of manufacture and maintenance, with lowwearcharacteristics. (1 fig., 2,000 words.)
Plasma thermofiltration In BP2184670, The Cleveland Clinic Foundation describes a method of filtration of macro molecules from fluids and more particularly the removal of undesirable macro molecules from plasma solutions moreselectively.
Plasma containing the macromolecules to beremoved is heated to a temperature nearor close to body temperature but below the boiling point of the plasma solution. The heated plasma solution is filtered at this temperature with a membrane filter to remove selectively macromolecules from the plasma solution. An apparatus to provide this process isdescribed. (6 figs., 12,000 words}
Two-phase liquidliquid extraction In BP 2184956, Kernforschungszentrum Karlsruhe GmbH describes a two-phase system for liquid-liquid extraction. It comprises anaqueous phase and an organic phase, one being the starting liquid where one or. more valuable materials are separated fromimpurities andfromoneanother in a multi-stage extraction apparatus. Valuable materials aretransferred by extraction from the starting liquid to the otherphase whichis washed with a washing liquid corresponding to thestarting liquid. Before being fed into the'extraction apparatus, the extractant phase is divided into at least two streams which are separately introduced at different points of the extraction apparatus ahead in their directionof flow.Theobjective of the invention is to improve the effectiveness of a liquid-liquid extraction process in a two-phase system where several valuable materials arepresent. Theinvention seeks to combine the advantages of the so-called concentrationflow scheme with thoseof the so-called flow dilute flow scheme. (6 figs., 6,000 words.)
Treating filter media
Automatic sampler TheSP3 autosampler hasbeen introduced by Paar Scientific to complement the DMA 48, microprocessor controlled, digital density meter. When linked, thetwo unitsaresaidto provide an automatic system for the accurate, fast measurement of density and specific gravity of liquids. gases andconcentrations of solids. The SP3 is suitable for use in qualitycontrolandotherlaboratories handling large quantities of samples each day, andcanbe left unattended for overnight sampling and linked to adataprocessor. Automatic measurement is carried out by a microprocessor controlled, menu-quided operation to minimise
60
cycle time.Asthesample is filled into the measuring cell by vacuum or pressure, viscous samples can also bemeasured automatically. A strong needle drive allows perforation of rubber sealed vials for measurement of toxic samples. and hasa speciafly designed sear to cover open vials. The samples are then transferred to the measuring cell by air/gas pressure. The SP3 has an automatic cycle for cleaning the sample feeding needle. Vials areoffered in a range of sizes from 10 to SOml and magazines are available whichholdfrom20up to 60 vials. Paar Scientific Ltd, 594 Kingston Road. Raynes Park. London SW20.
In BP 2185193, Labofina SA describes a method of treating spent filter media used in the clarification of liquid organic compounds, more particularly in recovering those organic compounds whichhave been sorbed in filter media. Filteraidsaremixed with aromatic solvents in two stages, the solvent from the first stage being distilledto separate out the additives; solvent is thenadded to thepartlycleaned filter aid in the second stage and wateris added before the two liquid and one solid phases areseparated by centrifuging. Thesolvent phase is then recycled to the first stage andthe waterto the second stage. (2 figs., 7.000 words.)
Lower cost duplex filter for mines In BP 2185418. DOlVty Mining Machinery Ltd describes a fluid filtering
system, in particular for use in the watersupply of mines. Two filtersare connected in parallel, the first being provided with a movable backflushing nozzle. Avalve normally directs flow through the first filter until rising flow necessitatesthe fluid being switched to the second filter while the first filter is backwashed. An element in the second filter is replaced periodically when dirty. The flow switching can be controlledautomatically byapressured drop monitor. Backwashing is effected by a nozzle which rotates as it is advanced axially inside anelement. Substantial savings in the cost of the system areclaimed because only one of the filter units needs be provided with means for backflushing. (4 figs. 5.000 wotds.)
Contaminants separated from gas In BP 2185422. David Victor Gent describes an apparatus for removing contaminants from a gas, suchasair found in industrial environments. It consists of a chamber with a gas inlet and outlet and a means for creating a curtain of washing liquid across the flow path of the gas between the two orifices. The curtain includes a rotatable imperforate disc and a nozzle located on one side of the disc and arranged coaxially thereto. The nozzle produces an emitted axial flow of liquid towards one side of the disc so as to contact the disc. The nozzle also causes the emitted flow of liquid to rotate aboutthe axis of the disc in thxsame direction as the rotation of the disc. (2 figs., 4,000 words.)
Coated filtering screens In BP2185698 Thule United Ltd describes improved filter screens, especially those for use in a vibrating screening apparatus used for screening drilling mud. The screen comprises a mesh with cores coated with a plastics material. Cores arepreferably of stainless steel or Kelvar. The plastics material, which should be abrasive resistant, may be applied to the mesh cores either before or after the cores are woven into themesh. Thickness of the coating is not criticaland may typically be between 2pm to 1mm. It may be applied by dip coating, solvent coating or spray coating. The properties of the screen, especially resistance to abrasion and adhesion, are improved by the coating process. (4 figs., 2,000 words.)
January/February 1989
Filtration & Separation