Abstract: Oxygen or oxygen-enriched air is employed to support combustion in furnaces (16) and (26) of part of the hydrogen sulphide content of a first feed gas stream. Sulphur vapour is extracted in condenser (32) from the resulting gas mixture so as to form a sulphur vapour depleted gas stream. The sulphur vapour depleted gas stream is passed into a catalytic reduction reactor (40) in which all the residual sulphur dioxide is reduced to hydrogen sulphide. This reduced gas mixture has water vapour extracted therefrom in a quench tower (52). The resulting water vapour depleted gas stream flows to a Claus plant for treatment typically together with a second feed gas steam comprising hydrogen sulphide. Employing both furnaces (16) and (26) makes it possible to obtain effective conversions to sulphur of the hydrogen sulphide in the feed gas without having the recycle any of the water vapour depleted gas.

Abstract: A scroll compressor which comprises a scroll assembly comprising two scroll walls, and a drive for causing a relative orbiting motion between the scroll walls for compressing fluid on two fluid flow paths between an inlet and an exhaust of the scroll assembly. A first fluid flow path is formed between a wall surfaces of the scroll walls and a second fluid flow path is formed between another facing wall surfaces of the scroll walls. A first ambient clearance A1 is selected between the first two facing surfaces, and a second ambient clearance A2 is selected between the second two facing surfaces, and where the first and the second ambient clearances are selected independently from each other. Independent selection permits each ambient clearance to be designed according to its own performance requirements, to take into account thermal expansion and manufacturing tolerances.

Abstract: A low-pressure processing vessel (3) used for the production of semiconductors is provided with a light-sensitive detector (1) at a distance from the reaction site, for example in the exhaust line (2). The detector (1) is used to detect light emitted by an intermediate which relaxes or recombines with the emission of light at a characteristic wavelength, the intermediate having a long lifetime such that the detector (1) can be positioned in a relatively remote location.

Abstract: Oxygen or oxygen-enriched air is employed to support combustion in furnace (16) of part of the hydrogen sulphide content of a first feed gas stream. Sulphur is extracted from the resulting gas stream in a sulphur condenser (26). Catalyst Claus reaction between hydrogen sulphide and sulphur dioxide in the resulting sulphur vapour depleted gas stream takes place in a catalytic reactor (32). Sulphur is extracted in a further sulphur condenser (34). The resulting sulphur vapour depleted gas stream is passed into a catalytic reduction reactor (40) in which all the residual sulphur dioxide and any sulphur vapour are reduced to hydrogen sulphide. The resulting reduced gas mixture has water vapour extracted there from in a quench tower (52). The resulting water vapour depleted gas stream flows to a Claus plant for further treatment typically together with a second feed gas stream.

Abstract: In a vacuum pump of the regenerative type or including a regenerative section in which a rotatable vertical shaft is supported by upper and lower bearings, a lubricating system for lubricating the upper bearing comprising an axial bore extending along the shaft and communicating at its upper end with at least one oil hole in alignment with the upper bearing, the lower open end of the axial bore extending in to a shaft reservoir located in a sump for containing lubricating fluid, the arrangement being such that centrifugal force generated by the rotation of the shaft will cause the lubricating fluid in the shaft reservoir to pass along the axial bore as a thin film towards the oil hole and hence to the upper bearing, in which at least one port is formed in a wall of the shaft reservoir to permit the passage of lubricating fluid therethrough from the sump in a controlled manner dependent upon the head of lubricating fluid in the sump above the port.

Abstract: A system for lubricating the upper bearing supporting a rotatable vertical shaft in a machine or pump comprising an axial bore extending along substantially the length of the shaft and communicating at its lower open end with a reservoir containing lubricating fluid, at least one radial oil hole extending between the axial bore and the upper bearing for the delivery of lubricating fluid thereto, the arrangement being such that centrifugal force generated during rotation of the shaft will draw lubricating fluid from the reservoir upwardly along the axial bore in the form of a thin film and towards the radial oil hole for delivery to the upper bearing, and an air delivery and demisting circuit including an air/lubricating fluid mist chamber communicating with the axial bore via at least one radial port located between the lower open end and the upper bearing, the port having a distal end extending in to the axial bore, at least one air hole extending between the axial bore and the outer cylindrical surface of t

Abstract: A reciprocating machine such as a vacuum pump includes a cylinder in which a reciprocating piston is disposed for reciprocating movement. A variable voltage driver is provided for driving the piston and a vibration sensor is provided for sensing contact between the piston and ends of the cylinder. A controller interconnects the sensor and driver to control movement of the driver and piston to maximize piston stroke and reduce if not eliminate contacting of the piston with the cylinder.

Abstract: In a method of cleaning metal surfaces to be welded together, at least one jet carrying particles of solid carbon dioxide is caused to come into contact with the surfaces, where the solid carbon dioxide is allowed to sublime at the surfaces. The jet is formed by passing a stream of pressurised liquid carbon dioxide through a nozzle under pressure.

Abstract: Nitrogen is rejected from a feed gas stream comprising methane and nitrogen so as to form a methane product. The feed gas is separated in a double rectification column comprising a higher pressure rectification column 14, a lower pressure rectification column 16, and a condenser-reboiler 18. Product methane is withdrawn from the column 16 by a pump 42 and is vaporised. A flow of gas is recycled from the column 16 to the column 14, being warmed in main heat exchanger 4. A first part of the warmed recycle gas being compressed in compressor 48 to a first pressure and introduced into the higher pressure rectification column 14. A second part of the warmed recycle gas is compressed in the compressor 48 and condensed in a second condenser-reboiler associated with an intermediate main exchange region of the lower pressure column 16 and is returned to the higher pressure rectification column 14.

Abstract: Small hot metal objects such as engineering components are quenched in gas by tumbling them in an upward flow of gas distributed uniformly from a multiplicity of openings 18 in the horizontal floor 4 of a quenching chamber 2. The tumbling is performed for a sufficient period of time for the objects to be quenched to a desired temperature. The quenching chamber 2 has a lower region 8 through which the flow of quenching gas is at an uniform velocity and an upper region 10 in which the velocity of the quenching gas is decreased.

Abstract: A nasal cannula for use in administering a gas under pressure through a nasal passage of a user comprises at least one tubular nasal prong assembly. The assembly includes an inner tubular prong 4 having a distal end to be placed in or adjacent the nasal passage and a proximal end for connection to a supply line 2 for the gas, and also includes an outer sleeve 8 extending over at least a portion of the inner tubular prong 4 to define therewith an annular passage 10 in communication with supply line 2. The arrangement is such that when gas flows through the supply line 2 most will flow out of the distal end of the prong 4 but some will pass through the annular passage 10 to form a shrouding stream.

Abstract: A vacuum pump system (10; 36; 46) for pumping gas from an enclosure (12) comprises: a vacuum pump unit (14) having a pump inlet (16) connectable with an outlet (18) of such an enclosure and a pump outlet (20) for exhausting gas; and a chamber (22; 50) selectively connectable with the pump inlet and the pump outlet, such that, in use, in a first state gas can be pumped from the chamber to the pump inlet by the vacuum pump unit and in a second state gas can be evacuated from the pump outlet to the chamber to reduce pressure at the pump outlet.

Abstract: A metallurgical lance for introducing gas from above into a volume of metal in a vessel includes a head having at least one ejector formed therein. The ejector includes a Laval nozzle surrounded by a shrouding gas passage. Both the Laval nozzle and the shrouding gas passage communicate at their proximal ends with a common gas supply chamber. The shrouding gas passage communicates with the chamber via a first annular orifice member which determines the percentage split of the gas flow through the chamber between the Laval nozzle and the shrouding gas passage.

Abstract: A seal assembly comprising a main O-ring seal element for engaging in a fluid tight manner opposed surfaces of two objects to be sealingly connected together and a barrier element positioned to protect all or a substantial portion of the surface of the main O-ring seal element against contact by the fluid when passing through the seal assembly from one object to the other object.

Abstract: A compound vacuum pump comprising at least one turbo-molecular stage and downstream therefrom a multi-channel molecular drag stage, a first inlet through which fluid can pass through the turbo-molecular stage and the molecular drag stage towards a pump outlet, a second inlet through which fluid can enter the pump at a location between the turbo-molecular and the molecular drag stages to pass only through the molecular drag stage towards the pump outlet, in which one or more channels of the molecular drag stage are adapted to communicate directly with the second inlet whilst the remaining channel or channels communicate with the turbo-molecular stage.

Abstract: A burner has a body portion and a main outlet. Fuel and primary oxidant outlets are arranged upstream of the main outlet and are disposed substantially concentrically about the axis of the burner. A chamber inside the body portion provides a place for the mixing of the fuel and oxidant. A laval nozzle provides acceleration of the mixed fuel and oxidant. Particulate matter are injected into a secondary oxidant flow immediately adjacent and downstream of the accelerating nozzle. The burner can be used in an electric arc furnace for decarburization of metals as well as post combustion. The burner can be mounted in a water-cooled box and can be fitted with an oxygen port for extra oxygen for post combustion while the burner injects hot oxygen and carbon for slag forming.

Abstract: A vacuum pump having a screw mechanism and comprising two externally threaded rotors mounted on respective shafts in a pump body and adapted for counter-rotation therein with intermeshing of the rotor threads with close tolerances between the threads and internal surfaces of the pump body in order that gas may be pumped from a pump inlet to a pump outlet by action of the rotor threads, the root diameter of each rotor increases and the thread diameter of each rotor decreases in a direction from the pump inlet to the pump outlet, and wherein the pitch of the rotor threads decreases in a direction from the pump inlet to the pump outlet.

Abstract: Objects formed of engineering and tool steels are quenched from above 850° C. by immersion in an aqueous suspension of inorganic particles. The greater the proportion of particles, the slower the quench. The suspension may be saturated with carbon dioxide.

Abstract: An air-oxygen hydrogen sulphide burner (108) fires into a furnace (102). The burner comprises a main passage for combustion-supporting gas containing air (112), a multiplicity of spaced apart outer elongate fluid-conducting open ended tubes extending in parallel with each other along the main passage, each of the outlet tubes surrounding at least at the distal end of the burner a respective inner elongate fluid-conducting open ended tube, the inner tubes extending in parallel with one another, a first inlet to the burner for oxygen or oxygen-enriched air, and a second inlet to the burner for feed gas containing hydrogen sulphide, the first inlet communicating with the inner tubs, and the second inlets communicating with the outer tubes.

Abstract: Nitrogen is rejected from a feed gas stream comprising methane and nitrogen so as to form a methane product. The feed gas stream is cooled in a main heat exchanger and is rectified in a double rectification column comprising a higher pressure rectification column, a lower pressure rectification column, and a condenser-reboiler placing the higher pressure rectification column in heat exchange relationship with the lower pressure rectification column. At least part of the feed gas stream is expanded into the higher pressure rectification column through an expansion valve, the feed gas stream being partially liquefied upstream of the double rectification column. Over a period of time the mole fraction of nitrogen in the feed gas mixture increases. At a suitable increased nitrogen mole fraction, operation of a second double rectification column in parallel with the first double rectification column is commenced.