Abstract: Nitrogen is separated from a first stream of compressed air in a higher pressure rectification column and from a second stream of compressed air in an intermediate pressure rectification column. Oxygen-enriched liquid is taken from the columns and separated in a lower pressure rectification column. An impure oxygen product is withdrawn in liquid state from the lower pressure column through an outlet. A part of the first air stream is condensed in a first condenser-reboiler, and a part of the second air stream is condensed in a third condenser-reboiler. Nitrogen separated in the higher pressure rectification column is condensed in a second condenser-reboiler, and nitrogen separated in the intermediate pressure rectification column is condensed in a fourth condenser-reboiler. The resulting nitrogen condensate is used as reflux in the columns. The condenser-reboilers provide reboil for the lower pressure rectification column.

Abstract: A pulse width modulated system for driving an inductive load. In the system, a switched current is supplied to the load. A duty cycle of the switched current is derived from a pulse width modulation controller and the amplitude of the switched current is determined. A multiplier device is provided to process the amplitude of the current supplied to a driver stage and to derive, in conjunction with the duty cycle, the load current.

Abstract: Air is separated in a vessel housing gas separation membranes. A flow control valve controls the passage of air to an inlet header of the vessel. The setting of the valve is adjusted in accordance with the level of oxygen impurity in product nitrogen leaving the vessel for an outlet header. A second flow control valve is provided and is of a kind whereby product nitrogen is able to be delivered at a constant flow rate over a range of different pressures upstream thereof. Accordingly, the apparatus is able to deliver nitrogen at a desired purity and flow rate.

Abstract: A part of the hydrogen sulphide content of a feed gas stream comprising hydrogen sulphide is burned by a burner that fires into a furnace. The combustion is supported by a stream of oxygen or oxygen-enriched air. Resulting sulphur dioxide reacts with residual hydrogen sulphide in the furnace to form sulphur vapor. Sulphur is condensed out of the resulting gas mixture in a sulphur condenser. At least part of the sulphur-free gas mixture flows through a reactor in which its sulphur dioxide content is reduced to hydrogen sulphide. Water vapor is removed from the resulting gas stream in a water condenser. At least part of the gas stream now essentially free of water vapor is recycled to the furnace. A purge stream is taken either from immediately downstream of the sulphur condenser or from intermediate the water condenser and the furnace, or from the furnace and, if desired, subjected to further treatment to remove sulphur-containing gases therefrom.

Abstract: An apparatus for dispensing a cryogenic liquid includes means for focusing a beam of energy, eg. laser energy from a source onto the liquid cryogen as it passes through an outlet from a cryogenic liquid container.

Abstract: A cooling apparatus comprises a cooling chamber (2), means (4) for introducing liquefied gas or its cold vapor thereinto, an exhaust passage (16) having flow inducing means associated therewith and a heat transfer means (46) associated with said exhaust passage (16) in which the heat transfer means operates to transfer heat from a heat source to the exhaust gas.

Abstract: A system for controlling the atmosphere of a container for use in the storage and/or transportation of perishable goods which includes adsorption apparatus for the selective adsorption in whole or in part and in a predeterminded order of any water vapor, carbon dioxide, oxygen or ethylene contained within the atmosphere, a blower for urging the atmosphere to the adsorption apparatus, and a conduiting for returning the controlled atmosphere to the container.

Abstract: A method and apparatus for treating a freshly metallized substrate in which a metal substrate is passed through a bath of molten metal for the purpose of applying a coating thereto while a treating gas containing a reducing gas, a non-oxidizing gas or combination thereof is provided at the region where the metallized substrate exits the molten metal bath to thereby at least reduce oxidation of the metallized substrate and the surface of the molten metal bath.

Abstract: A fault current limiter for use in alternating current transmission utilizes a (high temperature) superconductor body. If the current density through the body exceeds a critical value, the superconductor becomes a resistor; the fault current limiter makes use of this principle. In order to enable the critical current density to be selected from within a range of different values, the superconductor is immersed in a volume of cryogenic liquid, e.g. liquid nitrogen, in a vessel provided with a closure having an outlet communicating with a duct in which is disposed a manually adjustable back pressure regulator. The back pressure regulator enables the pressure in the ullage space of the vessel to be set at a chosen value, usually below atmospheric pressure. The liquid nitrogen is stored in the vessel at its boiling point which depends on the pressure in the ullage space. Accordingly, the temperature of the liquid nitrogen can be set by the regulator.

Abstract: Air is purified by being passed in sequence through a first, lower, bed of activated alumina particles which adsorb water vapor preferentially therefrom, and a second, upper, bed of zeolite 13X molecular sieve particles which adsorb carbon dioxide preferentially therefrom. The air passes upwardly through the first bed and downwardly through the second bed. Once fully loaded with the adsorbent components, the beds and are regenerated by the passage therethrough of hot regeneration gas. one part of the regeneration gas flows downwardly through the first bed; another part flows upwardly through the second bed. The hot regeneration gas causes the previously adsorbed components to be desorbed. Once regeneration has ended, and the beds have returned their adsorbing temperature, they may be used again to purify air.

Abstract: A first stream of cooled and purified air is introduced into a higher pressure rectification column 12 through an inlet 14 and is separated into oxygen-enriched liquid and nitrogen vapour. A stream of the oxygen-enriched liquid is flashed through a pressure reducing valve 40 into an intermediate rectification column 22 in which it is separated into further-enriched liquid and an intermediate nitrogen vapour. A stream of the further-enriched liquid is reboiled in condenser-reboiler 46 and is introduced into a lower pressure rectifier 34 comprising an upper stage 58 and a lower stage 60. The lower pressure rectifier 34 has a bottom condenser-reboiler 16 which is heated by a second stream of cooled and purified air. The second stream is itself condensed in the reboiler 16 and is introduced into the higher pressure column 12.

Abstract: Iron ore, coal and oxygen are fed to a reactor to produce iron and a fuel gas. The fuel gas leaves the reactor at a temperature of at least 200.degree. C. and is passed through a hot filtration apparatus. The resulting hot, filtered gas then passes through a heat exchanger. A heat exchange fluid, preferably a stream of nitrogen at above ambient pressure passes through the heat exchanger countercurrently to the hot filtered as stream. The heat exchange fluid is thereby heated. The hot heat exchange fluid stream is then expanded with the performance of external work in an expansion turbine, for example it may be used in the generation of electrical power. The hot, filtered, fuel gas may be sent for power recovery downstream of the heat exchanger or may be separated into its constituent components. If the heat exchange fluid is nitrogen it may be separated from air in the same plant that is used to feed the reactor with oxygen.

Abstract: Cooling apparatus comprises a cooling chamber such as a freezing tunnel having a pipeline for introducing liquid nitrogen into it and an exhaust passage for cold nitrogen vapor. The exhaust passage extends through a rotary regenerative heat exchanger. Downstream of the heat exchanger is a fan operable to draw the exhaust gas through the heat exchanger. A second passage extends through the heat exchanger and is arranged for the flow therethrough of relatively warm air, whereby, in operation, the air is able to transfer heat to the exhaust gas in the heat exchanger.

Abstract: A vacuum pump which includes an oil pump for raising the pressure of oil in the vacuum pump during operation of the vacuum pump and an inlet valve for isolating the vacuum pump inlet during non-operation of the vacuum pump. The vacuum pump has an operating valve acting in an oil line between the oil pump and the inlet valve and in an oil line between the inlet valve and an oil reservoir. The operating valve is movable by means of oil pressure between a second position associated with vacuum pump operation in which the oil line between the inlet valve and the oil reservoir is closed and a first position associated with vacuum pump non-operation in which the oil line between the inlet valve and the oil reservoir is open. A means is provided to allow high pressure oil from the oil pump to communicate with the inlet valve in at least the second position.

Abstract: A gas separation apparatus employing a membrane gas separation unit and containing a regenerative desiccant for preventing any free water contacting the membranes within the membrane separation unit.

Abstract: A rotary pump comprising a stator body having a bore and a rotor assembly mounted eccentrically in the bore to form a cavity between the stator body and the rotor assembly. The rotor assembly has two blades slidably positioned in diametrically opposed slots in the rotor assembly. In use of the pump the two blades are substantially in contact with an inner wall of the stator body. The stator body has an inlet and an outlet to allow, in use of the pump, fluid being pumped to enter into and be expelled from the cavity by means of the rotating vanes. The rotor assembly is of integral construction with each slot defined therein having an arcuate base and each blade has an end portion substantially conforming to the arcuate slot base.

Abstract: A first stream of compressed, cooled air is introduced into a higher pressure rectification column through an inlet and is separated into nitrogen vapour and oxygen-enriched liquid. At least some of the nitrogen vapor is condensed in a condenser and one stream of the resulting liquid nitrogen is used as reflux in the column and another stream as reflux in a lower pressure rectification column. Oxygen enriched liquid withdrawn from the column through an outlet is separated in the column. Impure liquid oxygen product is withdrawn from the column through an outlet. A less pure stream of liquid oxygen is withdrawn from the column through an outlet, is reboiled in a condenser-reboiler by indirect heat exchange with a second stream of air and is reintroduced into the column at its bottom through an inlet.

Abstract: A mechanical vacuum pump is provided with a pair of cooperating rotors mounted on rotatable shafts within a pumping chamber. Each of the pair of cooperating rotors has a claw profile that terminates in a leading edge shaped to present an angle of no greater than 90 degrees relative to the wall of the pumping chamber. The leading edge shaped in such manner helps to prevent contaminant buildup on the wall of the pumping chamber.

Abstract: An anaesthetic vaporizer includes a passageway 10, 30 for directing carrier gas through a fixed laminar restrictor 32 to a vaporizing chamber 26. Liquid anaesthetic agent is injected into the vaporizing chamber 26 from a constant level tank 12 the output of which is controlled by a laminar control valve 28. Liquid anaesthetic agent flow is determined by the pressure of carrier gas in the passageway 10, 30 and the setting of the liquid laminar control valve 28.

Abstract: Apparatus for sputtering coatings of material onto a substrate from a chamber subject to substantial evacuation during use, which includes: a substantially cylindrical target tube having on a surface thereof the material to be sputtered, means for rotating the target tube about its longitudinal axis, magnetic means for assisting the sputtering process by the provision of a magnetic field in a sputtering zone associated with the target tube, means for moving the substrate through the chamber and into the sputtering zone, means for introducing an ionisable gas and a reactive gas into the chamber in the vicinity of the sputtering zone, wherein supplementary magnetic means are provided to form a supplementary magnetic field remote from the sputtering zone and means are provided to introduce ionisable gas in the vicinity of the supplementary magnetic field.