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Screen separator
INVENTIONSINFILTRATIONANDSEP Abstracts of recent British Patents Centrifugal separator
Gas filter
In GB 2260915 Centrifugal & Mechanical Industries Inc describes a vertical, centrifugal separator, which includes a drive mechanism for rotating a flight assembly and a screen at different speeds. Material to be separated falls between the flight and screen assemblies during separation. A pocket integral with the upper end of the screen creates a ‘basket’ for catching material from the inlet, and replaces the upper part of the screen, extending the screen life. The screen includes a rotor with spokes defining an outlet for separated solids. The spokes have wear pads attached. The outlet for solids has a side wall lined with ceramic plates, to resist solids impacts. An annular liquid outlet is also provided.
In GB 2261830 Process Scientific Innovations Ltd describes a tubular filter for removing oil mist from a stream of air or other gas. A coalescing layer and a drainage layer are provided. The lower end of the coalescing layer is sealed into and closed by an end cap. The lower end of the drainage layer is generally uncompressed and unobstructed, extending axially below the end of the coalescing layer, and is located within an outer annular zone of the end cap, which provides channels through which coalesced oil drops can drain. The lower saturated part of the drainage layer is enclosed by a sleeve, and is shielded from the air flow to minimise re-entrainment. The sleeve carries gripping formations.
High-efficiency air filter
Filtering hot gases
In GB 2260916 Pall Corporation describes a high-efficiency air filter. It comprises a depth filter sheet that has been formed with micropleats stabilised by application of one or more strips of a thermoplastic adhesive across the peaks of the micropleats, and then formed into a macropleated structure with the axes of the micropleats and the macropleats being parallel. The strips may be melted at intervals to allow some of the micropleats to be opened out, to form flat pleats of the macropleats. Such peaks are narrower on the inlet side.
In GB 2261831 Ahlstrom Corporation describes hot gas filtration. Before a hot gas (above 400°C) is filtered by tubular ceramic elements, it is passed through a temperature-stabilising chamber containing bricks or metal bars, which have enough thermal capacity to even out sudden temperature variations, protecting the elements. Chamber and elements are in the same pressure vessel as the fluidised bed in which the gas is produced, but can be fitted in a separate vessel. The bricks can be arranged in a cage, or rectangular metal bars stacked on edge to form a grid structure.
Solid/liquid separation In GB 2261612 Jones & Attwood Ltd describes a method for separating solids from liquids. Grit is separated from sewage in two stages: the first comprises a settling tank, from the sump of which a liquid mixture of settled grit and organic contaminants is pumped to the inlet of the second stage. This latter stage comprises an elongated, inclined trough in which the grit settles, while organics are carried along with the liquid flow. The trough may be inclined, with uphill, downhill or horizontal flow. The liquid flows out of the trough to the left of a baffle, but after some grit has accumulated the flow is stopped and the trough is tilted, pulling its outlet end to the right of the baffle. The grit is then flushed or scraped out. Grit can also be removed by blades on an endless conveyor, or by a screw device lowered into the trough when required. Grit may also be flushed from a tilted trough into a hopper with an inclined screw conveyor. The trough may be vibrated in use. Flltratlon & Separation
January/February
1994
Magnetic separation In GB 2261833 CSIR describes a magnetic separator. It has an endless belt, which has an upper run moving upward in use. A mixture of magnetically susceptible and non-susceptible material is poured in a flow stream onto the upper run in a separation area, where a magnetic pack is provided close underneath the run. Magnetically non-susceptible material flows under gravity against the movement of the run, and is dumped. Magnetically susceptible material is checked by means of the magnetic pack, and then moves with the run, upwards and against gravity, to be recovered.
Filtering apparatus In GB 2262244 Profit Improvement & Engineering Ltd describes a filtering apparatus comprising an endless woven, synthetic filament filter belt, of which the lower run is driven through a tank containing contaminated liquid. Liquid is drawn up through the belt
into the mouth of a syphon, and delivered through a valve to a second tank While the filter is operating, the liquid level in the first tank is maintained above the mouth of the siphon, by pumping contaminated liquid from a third tank and allowing excess to flow back to the tank over an adjustable weir in the first tank. The belt is washed by fixed and oscillating sprays, fed from the second tank. The pump also fills the siphon to start the filtering process.
Screen separator In GB 2262456 Anglo American Corporation of South Africa Ltd describes a screen separator. Metal valves are progressively adsorbed from a metalrich liquid (pulp) which is circulated through a series of tanks containing adsorbent (carbon or resin) particles. Each tank encloses a cylindrical screen, which in turn encloses a rotary impeller which pumps the liquid in through the screen and out of the tank, while the screen retains the absorbent within the tank. The screen is closed at the bottom by a tubular baffle. A shaft extends through this car&g an impeller inside the screen, and a second impeller and blades outside the screen. The top of the screen is open, and screened liquid is lifted by the rotary impeller and falls into the annular channel to be fed to the next tank. The second impeller improves contact between liquid and adsorbent, and blades clean the screen, Flow is periodically stopped, and saturated adsorbent is removed for further treatment to recover the metal.
Fluid filter In GB 2262706 Filterwerk Mann & Hummel GmbH describes a generally flat fuel or transmission fluid filter, comprising a filter element sandwiched between connected (but releasable) upper and lower housing shells, which are provided with inlet and outlet fittings, respectively. Lugs on a shell are engaged under flanges on the shell along one edge of the housing, and snap fastenings connect the shells along the opposite edge. The snap fastenings can be replaced by pins with cross-members, inserted through aligned slots and then rotated a quarter-turn to cam the shell together. U-shaped springs on one shell carry latches designed to snap into recesses around the other shell. The filter element may be flat, pleated or bagshaped, and may be separate from or integral with the sealing ring.
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Gas filter
In GB 2260915 Centrifugal & Mechanical Industries Inc describes a vertical, centrifugal separator, which includes a drive mechanism for rotating a flight assembly and a screen at different speeds. Material to be separated falls between the flight and screen assemblies during separation. A pocket integral with the upper end of the screen creates a ‘basket’ for catching material from the inlet, and replaces the upper part of the screen, extending the screen life. The screen includes a rotor with spokes defining an outlet for separated solids. The spokes have wear pads attached. The outlet for solids has a side wall lined with ceramic plates, to resist solids impacts. An annular liquid outlet is also provided.
In GB 2261830 Process Scientific Innovations Ltd describes a tubular filter for removing oil mist from a stream of air or other gas. A coalescing layer and a drainage layer are provided. The lower end of the coalescing layer is sealed into and closed by an end cap. The lower end of the drainage layer is generally uncompressed and unobstructed, extending axially below the end of the coalescing layer, and is located within an outer annular zone of the end cap, which provides channels through which coalesced oil drops can drain. The lower saturated part of the drainage layer is enclosed by a sleeve, and is shielded from the air flow to minimise re-entrainment. The sleeve carries gripping formations.
High-efficiency air filter
Filtering hot gases
In GB 2260916 Pall Corporation describes a high-efficiency air filter. It comprises a depth filter sheet that has been formed with micropleats stabilised by application of one or more strips of a thermoplastic adhesive across the peaks of the micropleats, and then formed into a macropleated structure with the axes of the micropleats and the macropleats being parallel. The strips may be melted at intervals to allow some of the micropleats to be opened out, to form flat pleats of the macropleats. Such peaks are narrower on the inlet side.
In GB 2261831 Ahlstrom Corporation describes hot gas filtration. Before a hot gas (above 400°C) is filtered by tubular ceramic elements, it is passed through a temperature-stabilising chamber containing bricks or metal bars, which have enough thermal capacity to even out sudden temperature variations, protecting the elements. Chamber and elements are in the same pressure vessel as the fluidised bed in which the gas is produced, but can be fitted in a separate vessel. The bricks can be arranged in a cage, or rectangular metal bars stacked on edge to form a grid structure.
Solid/liquid separation In GB 2261612 Jones & Attwood Ltd describes a method for separating solids from liquids. Grit is separated from sewage in two stages: the first comprises a settling tank, from the sump of which a liquid mixture of settled grit and organic contaminants is pumped to the inlet of the second stage. This latter stage comprises an elongated, inclined trough in which the grit settles, while organics are carried along with the liquid flow. The trough may be inclined, with uphill, downhill or horizontal flow. The liquid flows out of the trough to the left of a baffle, but after some grit has accumulated the flow is stopped and the trough is tilted, pulling its outlet end to the right of the baffle. The grit is then flushed or scraped out. Grit can also be removed by blades on an endless conveyor, or by a screw device lowered into the trough when required. Grit may also be flushed from a tilted trough into a hopper with an inclined screw conveyor. The trough may be vibrated in use. Flltratlon & Separation
January/February
1994
Magnetic separation In GB 2261833 CSIR describes a magnetic separator. It has an endless belt, which has an upper run moving upward in use. A mixture of magnetically susceptible and non-susceptible material is poured in a flow stream onto the upper run in a separation area, where a magnetic pack is provided close underneath the run. Magnetically non-susceptible material flows under gravity against the movement of the run, and is dumped. Magnetically susceptible material is checked by means of the magnetic pack, and then moves with the run, upwards and against gravity, to be recovered.
Filtering apparatus In GB 2262244 Profit Improvement & Engineering Ltd describes a filtering apparatus comprising an endless woven, synthetic filament filter belt, of which the lower run is driven through a tank containing contaminated liquid. Liquid is drawn up through the belt
into the mouth of a syphon, and delivered through a valve to a second tank While the filter is operating, the liquid level in the first tank is maintained above the mouth of the siphon, by pumping contaminated liquid from a third tank and allowing excess to flow back to the tank over an adjustable weir in the first tank. The belt is washed by fixed and oscillating sprays, fed from the second tank. The pump also fills the siphon to start the filtering process.
Screen separator In GB 2262456 Anglo American Corporation of South Africa Ltd describes a screen separator. Metal valves are progressively adsorbed from a metalrich liquid (pulp) which is circulated through a series of tanks containing adsorbent (carbon or resin) particles. Each tank encloses a cylindrical screen, which in turn encloses a rotary impeller which pumps the liquid in through the screen and out of the tank, while the screen retains the absorbent within the tank. The screen is closed at the bottom by a tubular baffle. A shaft extends through this car&g an impeller inside the screen, and a second impeller and blades outside the screen. The top of the screen is open, and screened liquid is lifted by the rotary impeller and falls into the annular channel to be fed to the next tank. The second impeller improves contact between liquid and adsorbent, and blades clean the screen, Flow is periodically stopped, and saturated adsorbent is removed for further treatment to recover the metal.
Fluid filter In GB 2262706 Filterwerk Mann & Hummel GmbH describes a generally flat fuel or transmission fluid filter, comprising a filter element sandwiched between connected (but releasable) upper and lower housing shells, which are provided with inlet and outlet fittings, respectively. Lugs on a shell are engaged under flanges on the shell along one edge of the housing, and snap fastenings connect the shells along the opposite edge. The snap fastenings can be replaced by pins with cross-members, inserted through aligned slots and then rotated a quarter-turn to cam the shell together. U-shaped springs on one shell carry latches designed to snap into recesses around the other shell. The filter element may be flat, pleated or bagshaped, and may be separate from or integral with the sealing ring.
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