Abstract: In a method and apparatus for separating air a distillation zone is employed to separate air into an oxygen-enriched liquid fraction and a nitrogen-enriched vapor-fraction. A first stream is taken from the nitrogen-enriched vapor fraction and is mixed with a stream taken from the oxygen-enriched liquid fraction. At least part of the resultant mixture is employed to perform a refrigeration duty, for example the condensation of nitrogen-enriched vapor to provide reflux for the distillation column.

Abstract: In a process for the separation of argon from a gaseous mixture comprising argon, nitrogen and oxygen by fractional distillation in a plurality of distillation zones, first and second fluid streams comprising nitrogen and oxygen, respectively, drawn from the same or different distillation zones, are introduced into different regions of a liquid-vapor contact and mixing zone. There is established in the contact and mixing zone a liquid flow that becomes progressively richer in nitrogen and a vapor flow that becomes progressively richer in oxygen. A mixed waste stream containing both oxygen and nitrogen is withdrawn from an intermediate point in the contact and mixing zone thereby enhancing its efficiency. Vaporous oxygen from the warmer end of the contact and mixing zone is condensed and returned to the mixing zone to enhance its reflux and/or may be passed into a distillation zone.

Abstract: A humidifying module 4 is releasably attachable to a heater unit 2 to form an apparatus for delivering humidified gas to a patient and includes a substantially flat wick 6 which absorbs water without any substantial change in its surface area. The wick is contained within a chamber defined by a substantially flat back plate 10 and a front plate 12 including an inlet 20 for gas to be humidified and an outlet 22 for humidified gas.

Abstract: An apparatus 1 for mixing first and second gases includes first and second valves 2, 3 each having a stem 14 the axial movement of which controls the flow of the gases through their respective valves. Each valve stem has one end engaging a control surface 16 of a thrust plate 18 mounted for axial and pivotal movement on a shaft 20. Means including a plunger 26 is provided for pivoting the thrust 18 so that one valve stem is moved axially relative to the other thereby increasing the rate of flow of one gas through its respective valve while concomitantly decreasing the rate of flow of the other gas through its respective valve to vary the relative proportion of the gases without varying the total flow rate. Total flow adjuster 34 bears on the plunger 26 for moving the thrust plate 18 axially towards and away from the valve stems 14 thereby to vary the total rate of flow of the gases without varying the relative proportions of each gas flowing through its respective valve.

Abstract: A composite flexible delivery hose 1 for use with a medical humidifier comprises an inner tubular member 2 around which is spirally wound a heater cable 4. The heater cable 4 includes an outer body 6 of electrically insulating material in which is embedded an electrical resistance heater wire 8, a wire 10 interconnecting temperature sensors arranged one at each end of the hose and a thermoplastic support wire 12.

Abstract: A vaporizer includes means 11 which may be an electronically controlled solenoid valve to divert repeatedly a carrier gas into either a first path which goes directly from the inlet 3 to the outlet 5 of the vaporizer or a second path which enters a vaporizing chamber 13 to entrain volatile liquid vapor before re-joining the first path.

Abstract: A humidifier includes a chamber 14 having an inlet 30 and an outlet 6. The chamber 14 is releasably attached to a heater unit including a heater 22 and a heat sensor 24. When the chamber 14 and the heater unit are assembled together the heater 22 is in thermal contact with a heat transfer surface of the chamber 14 at or adjacent the inlet port 30 while the temperature sensor 24 is in thermal contact with the heat transfer surface at or adjacent the outlet port 6.

Abstract: In order to dissolve a gas such as oxygen in a liquid, typically aqueous, a stream of liquid is taken from tank 2 by a pump 10 and pressurized thereby. Oxygen is introduced into the stream via a conduit 18 upstream of a venturi 20. The resulting mixture of oxygen bubbles and liquid is accelerated from a sub-sonic to a super-sonic velocity as it flows through the venturi 20. The resultant shockwave is effective to reduce the size of the bubbles. The stream of liquid carrying oxygen bubbles dispersed therein is then transported at sub-sonic velocity along the conduit 12 to a sparge pipe 14 through which it is introduced into the main volume 4 of liquid into the tank 2. As the liquid passes through the orifices of the sparge pipe 14 so it is again accelerated to a super-sonic velocity and another shockwave is created thereby causing the bubbles to reduce in size such that they readily dissolve in or are consumed by the main volume of liquid.

Abstract: A method of liquefying a permanent gas stream includes the step of reducing the temperature of the permanent gas stream at elevated pressure to below its critical temperature. The reduction in temperature is effected at least in part by countercurrent heat exchange with work expanded working fluid, at least some of which is at a temperature below the critical temperature of the permanent gas when it is brought into heat exchange relationship with the permanent gas stream. The permanent gas stream after being cooled to below its critical temperature is then subjected to at least three successive isenthalpic expansions. Resulting flash gas is separated from the resulting liquid. At least some of the flash gas is heat exchanged with the permanent gas stream at elevated pressure.

Abstract: A method of liquefying a permanent gas stream, includes the steps of reducing the temperature of the permanent gas stream at elevated pressure to below its critical pressure and performing at least two working fluid cycles to provide at least part of the refrigeration necessary to reduce the temperature of the permanent gas to below its critical temperature. Each working fluid cycle comprises work-expanding the cooled working fluid in countercurrent heat exchange with the permanent gas stream and with the working fluid being cooled, refrigeration thereby being provided for the permanent gas stream. In at least one working fluid cycle, work-expanded working fluid is brought into countercurrent heat exchange relationship with the permanent gas stream at a temperature below the critical temperature of the permanent gas and in the or each such cycle on completion of the work expansion the working fluid is at a pressure of at least 10 atmospheres.

Abstract: An anaesthetic vaporizer of the by-pass type in which the concentration of anaesthetic vapor in the gas leaving the vaporizer is controlled by a valve arrangement which is capable of varying the resistance to gas flow of a second or by-pass stream which effectively alters the proportion in which the carrier gas is divided between said second by-pass stream and a first stream which passes through a vaporizing chamber. The valve arrangement includes a valve body 32 rotatable within a valve housing 30 having three spaced inlet holes 33, 35, 37 and an outlet hole 40 for the second gas stream. Rotary movement of the valve body 32 variously covers or uncovers the inlet holes 33, 35 and 37 to vary the resistance to the flow of the second stream from the inlet holes to the outlet hole 40 of the housing 30.

Abstract: In cooling a permanent gas stream (e.g. of nitrogen) at elevated pressure to below its critical temperature (e.g. in a process for the liquefaction of the permanent gas), the stream is heat exchanged with a main stream of working fluid (typically also nitrogen) that has been work-expanded in expansion turbine. The refrigeration provided by this stream is supplemented by that provided by at least two supplementary streams of work expanded working fluid. The temperatures at which the supplementary streams are introduced into heat exchange relationship with the permanent gas stream are in a defined range extending from 5.degree. K. above the point at which the rate of change of the heat capacity (at constant pressure) of the gas per standard cubic meter increases by about 1% per Kelvin as the gas is cooled to 5.degree. K. below the point at which the rate of change with temperature of the heat capacity (at constant pressure) of the gas per standard cubic meter is at a maximum.

Abstract: A fuel burner 2 for burning a fuel such as pulverized coal carried by a fluid, particularly air, has an inner passage for the particulate fuel-carrier medium and an outer passage for a combustion-supporting gas (typically oxygen-enriched air or pure oxygen). The inner passage typically terminates in a nozzle having an orifice therethrough. The inner passage 12 is surrounded by a jacket containing a pressurized fluid. A pressure sensor senses the pressure in the jacket. In the event that abrasive wear of the inner passage causes holes to be formed therein, fluid will pass from the jacket into the inner passage causing a pressure drop in the jacket which is sensed by the pressure sensor. The burner may then be shut down without any hazard having been caused by contact between the pulverized coal and pure oxygen or oxygen-enriched air. The burner may also be used for the autogenous oxidation or thermal cracking of chemicals.

Abstract: A composition comprising a particulate fuel, typically pulverized coal, carried in water is formed such that it is readily able to be pumped without adding emulsifiers or lubricants to the composition. The composition typically includes at least 25% water and preferably 30 to 50% water. The composition is pumped to a burner 2 and is atomized therein, typically by means of a stream of oxygen supplied through a passage 6 in the nozzle 6 of the burner. This oxygen is taken from that supplied to a further passage for supporting combustion of the particulate fuel. A relatively short and intense flame can be produced at relatively low coal concentrations in the composition such that the need to use expensive emulsifiers etc. is avoided.

Abstract: A gas mixing apparatus in the form of an anaesthesia apparatus includes a first path for oxygen, a second path for nitrous oxide and third path for carbon dioxide. The first path is divided for at least a part of its length into first and second by-pass passages 210, 212. A valve 214 in the first by-pass passage 210 is inter-connected with a valve 222 controlling the flow of a nitrous oxide through the second path and a valve 215 in the second by-pass passage 212 is interconnected with a valve 232 controlling the flow of carbon dioxide through the third path. The interconnecting means 250, 260 are so arranged that the opening of the valves 222, 232 associated with the second and third paths causes corresponding opening of the valves 214, 215 associated with the by-pass passages such that the total flow of oxygen through the apparatus will never fall below a predetermined minimum proportion by volume.

Abstract: A continuous heat treatment furnace has an entrance, a preheat zone, a thermal treatment zone, a cooling zone and an exit. Curtains are provided at the entrance and exit respectively. Nitrogen and hydrogen (or other reducing gas) are supplied to the furnace to create a non-oxidizing or reducing atmosphere in the thermal treatment and cooling zones. Elongate workpieces such as tubes are advanced through the furnace and thereby heat treated (e.g. annealed). As the workpieces pass through the curtains so the tendency for air to leak into the furnace is increased. To counteract this tendency, position sensing plates are adapted to actuate a signal generator controlling a valve which in turn controls flow of e.g. nitrogen to the furnace. The arrangement is such that the flow of nitrogen to the furnace is increased wherever a workpiece is sensed, thereby enabling the essentially reducing or non-oxidizing character of the atmosphere to be sustained.

Abstract: A mechanical pump includes a pumping chamber through which extends a pair of parallel shafts 3. Each shaft 3 carries in tandem rotors 4, 5 and 6 at least two of which are the intermeshing "claw" type. The rotors are arranged in complementary pairs and each pair occupies a separate location in the pumping chamber. Each "claw" type rotor 6 of a complementary pair in one location is mounted on its shaft 3 in reverse orientation to the "claw" type rotors 5 of the complementary pairs in the adjacent location.

Abstract: In a pressure swing adsorption process for the production of nitrogen enriched product gas from air, when the process is halted during a pressure equalization step, that is, with valves open to permit the flow of gas from one vessel to a second vessel, then the gas remaining in the vessels is exhausted to atmosphere by opening a further valve. This results in rapid return to the required purity of nitrogen enriched product gas on start-up of the process. Preferably, subsequent to opening the further valve, another valve is opened, thereby permitting nitrogen-rich product gas from a reservoir to flow through the vessels, thereby purging said vessels with nitrogen enriched product gas.

Abstract: In a method of freezing a liquid such as cream, a continuous, pulsating stream of liquid is dispensed from nozzles onto a stream of liquified gas flowing along downwardly inclined channels provided by a trough. The liquid forms itself into discrete spheroidal bodies, a substantial number of which have a larger cross-sectional area than that defined by the outlet of each nozzle from which they are dispensed. The bodies are carried by the liquified gas along the channels and at least their peripheries are frozen by the time the bodies reach the downstream end of the channels. Freezing may be completed by gas cooling. The bodies are then separated from the liquified gas.

Abstract: A method and an apparatus for dissolving gas in a body of sewage comprising providing a skirt member having a lower open end extending upwardly from said body of sewage to define a volume of said sewage separate from an adjacent body of clarified liquid in said tank, removing a flow of sewage from said body of sewage and pressuring said flow, introducing oxygen into said pressurized flow to form a mixture of oxygen and sewage, introducing said mixture as a jet downwardly into the inlet of a chamber disposed in said volume defined by said skirt member to induce sewage in said chamber and thereby oxygenate said sewage, discharging said oxygenated sewage downwardly through an outlet of said chamber at a reduced velocity, and reducing the momentum of said discharged oxygenated sewage by directing the same onto baffles spaced from the outlet of said chamber.