Patents Assigned to The BOC Group plc
  • Patent number: 5372127
    Abstract: A sump for an anaesthetic vaporiser comprises a vaporising chamber for liquid anaesthetic agent, a heater for liquid anaesthetic agent contained within the chamber, and a partition member of which at least a portion extends into the chamber to entrap a portion of liquid anaesthetic agent at a location in close proximity to the heater, the member having a partition outlet for anaesthetic agent vapor through the partition member at a position above the maximum level of anaesthetic agent within the partition member. The partition member allows a portion only of liquid anaesthetic agent within the vaporizing chamber to be heated, so that the temperature required of the liquid agent for operation of the vaporiser can be reached rapidly. The sump finds particular application in connection with the use of low boiling point anaesthetic agents such as 2 -(difluoromethoxy) 1,1,1,2 -tetrafluoroethane.
    Type: Grant
    Filed: March 25, 1993
    Date of Patent: December 13, 1994
    Assignee: The BOC Group plc
    Inventors: David J. Thwaites, David C. Sampson
  • Patent number: 5361590
    Abstract: A medium purity gaseous oxygen cycle in which reboil for the LP column is provided partly by nitrogen from the HP column and partly by a stream of air.
    Type: Grant
    Filed: May 21, 1993
    Date of Patent: November 8, 1994
    Assignee: The BOC Group plc
    Inventor: Thomas Rathbone
  • Patent number: 5354172
    Abstract: A vacuum pump of the molecular drag type comprising a pump body, a cylindrical element adapted for rotation within the pump body about its longitudinal axis and having a plurality of circumferential slots defined in its surface which are substantially perpendicular to the longitudinal axis, a stator element held stationary with regard to the pump body and having projections extending into the slots substantially to fill the slots in the vicinity of the stator, wherein at least some of the surfaces of the stator projections adjacent the walls of the slots are coated with an abradable material.
    Type: Grant
    Filed: December 3, 1992
    Date of Patent: October 11, 1994
    Assignee: The BOC Group plc
    Inventor: Nigel P. Schofield
  • Patent number: 5352433
    Abstract: A hydrogen sulphide containing feed gas stream (typically including at least 70% by volume of hydrogen sulphide) is divided into a minor stream and a major stream. The minor stream is burnt in a first combustion region to form sulphur dioxide and water vapor. The resulting gas mixture is cooled in a heat exchanger and is employed in a second combustion region in which a portion of the hydrogen sulphide content of the major stream is burnt to form sulphur dioxide and water vapor. Reaction between the sulphur dioxide and remaining hydrogen sulphide takes place in a thermal reaction region to form sulphur vapor and water vapor. The proportions of sulphur burnt in the respective combustion regions and are chosen such that about one-third of the total hydrogen sulphide content of the feed gas stream is burnt to sulphur dioxide in these regions.
    Type: Grant
    Filed: March 2, 1987
    Date of Patent: October 4, 1994
    Assignee: The BOC Group plc
    Inventor: Richard W. Watson
  • Patent number: 5346183
    Abstract: A hot coke bed is established at the bottom of a vertical shaft furnace, e.g. an iron melting cupola. The cupola is then charged with alternate layers of ferrous metal and coke material, respectively. Burners burn hydrocarbon fuel in the presence of a stoichiometric excess of oxygen-enriched air and thus form a hot gas mixture including oxygen. The hot gas mixture passes upwards through the shaft of the cupola thereby providing sufficient heat to melt the ferrous metal. Molten ferrous metal flows downwards under gravity into and through the coke bed and may be removed through a tap hole. At least one jet of oxygen is injected into the hot coke bed so as to maintain it at a temperature sufficient to superheat the molten metal. Preferably a fan is operated to dilute with air the combustion gases above the level of the charge in the shaft and thereby create secondary flames. No air blast is supplied to the cupola.
    Type: Grant
    Filed: October 12, 1993
    Date of Patent: September 13, 1994
    Assignee: The BOC Group plc
    Inventor: David R. Westley
  • Patent number: 5344282
    Abstract: A vacuum pump of the molecular drag type comprising a pump body, a cylindrical element adapted for rotation within the pump body about its longitudinal axis and having a plurality of circumferential slots defined in its surface which are substantially perpendicular to the longitudinal axis, a stator element held stationary with regard to the pump body and having projections extending into the slots substantially to fill the slots in the vicinity of the stator, wherein the cylindrical element comprises a co-axial assembly of a plurality of individual discs, each disc being spaced apart from its adjacent disc(s), thereby defining the circumferential slots between the discs.
    Type: Grant
    Filed: December 3, 1992
    Date of Patent: September 6, 1994
    Assignee: The BOC Group, plc
    Inventor: Nigel P. Schofield
  • Patent number: 5339639
    Abstract: A refrigerator includes a cylinder containing a bed of adsorbent material and a gas, e.g. carbon dioxide. A piston compresses the gas which is adsorbed by the adsorbent material and the heat of adsorption is dissipated by fins to atmosphere. The piston, when retracted, decompresses the gas which desorbs from the adsorbent material. Repeated compression and decompression of the gas causes a cold zone to be created within the material which is thermally linked to a location to be refrigerated.
    Type: Grant
    Filed: July 2, 1992
    Date of Patent: August 23, 1994
    Assignee: The BOC Group Plc.
    Inventor: Michael E. Garrett
  • Patent number: 5331818
    Abstract: Air is rectified in a rectification system comprising a higher pressure rectification column, an intermediate pressure rectification column, and a lower pressure rectification column. A first reboiler-condenser provides liquid nitrogen reflux for the higher pressure rectification column and for the lower pressure rectification column and also reboils the intermediate pressure rectification column. Another reboiler-condenser provides liquid nitrogen reflux for the intermediate pressure rectification column and reboils the lower pressure rectification column. Air is fed to the higher pressure rectification column through a pair of inlets. A first oxygen product is withdrawn from the intermediate pressure rectification column by a pump. Gaseous nitrogen products are withdrawn from the intermediate and lower pressure rectification columns through a pair of outlets thereof.
    Type: Grant
    Filed: June 23, 1993
    Date of Patent: July 26, 1994
    Assignee: The BOC Group plc
    Inventor: Thomas Rathbone
  • Patent number: 5320274
    Abstract: A soldering apparatus includes a conveyor adapted to carry assembled circuit boards through a soldering chamber. A wave of solder is created in the chamber. The chamber has a curtain at its entrance and a curtain at its exit. Gas distributors are located within the chamber and are able to introduce nitrogen into the chamber in order to create a non-oxidizing atmosphere in the vicinity of the wave. In operation, the wave of solder wets connecting points between the components and the board to form permanent joints on solidification of the solder. The bottom edge of the curtain is of a shape complementary to the front elevation of the assembled circuit boards to be soldered and is arranged such that the circuit boards just pass thereunder without making contact with it.
    Type: Grant
    Filed: September 30, 1992
    Date of Patent: June 14, 1994
    Assignee: The BOC Group plc
    Inventors: Colin J. Precious, Raymund Thomas
  • Patent number: 5317862
    Abstract: In a process integration, particularly with a blast furnace, nitrogen under pressure is moisturized by the addition to it of hot, pressurized water. The moisturized nitrogen is expanded and power thereby generated. The nitrogen is not mixed with combustion gases. Improved heat balance and work recovery are achieved.
    Type: Grant
    Filed: April 6, 1993
    Date of Patent: June 7, 1994
    Assignee: The BOC Group, plc
    Inventor: Thomas Rathbone
  • Patent number: 5317270
    Abstract: A vacuum guage of the ionisation type having a guage head comprising a substantially cylindrical cathode sleeve with an inlet at one end for communication with the vacuum with an anode positioned co-axially within the cathode sleeve; the head also has a guard ring interposed between the cathode sleeve and the anode and a vacuum feed through arrangement in which the anode and the guard ring are held substantially concentrically within the cathode sleeve.
    Type: Grant
    Filed: May 28, 1992
    Date of Patent: May 31, 1994
    Assignee: The BOC Group plc
    Inventor: Paul G. Lethbridge
  • Patent number: 5309721
    Abstract: An improvement to a gaseous oxygen cycle in which refrigeration is provided by two expansion turbines each fed with nitrogen. In addition, some nitrogen is recompressed, returned though the main heat exchanger, condensed and used to form a liquid nitrogen product.
    Type: Grant
    Filed: April 6, 1993
    Date of Patent: May 10, 1994
    Assignee: The BOC Group plc
    Inventor: Thomas Rathbone
  • Patent number: 5304232
    Abstract: A hot coke bed is established at the bottom of a vertical shaft furnace, e.g. an iron melting cupola. The cupola is then charged with alternate layers of ferrous metal and coke material, respectively. Burners burn hydrocarbon fuel in the presence of a stoichiometric excess of oxygen-enriched air and thus form a hot gas mixture including oxygen. The hot gas mixture passes upwards through the shaft of the cupola thereby providing sufficient heat to melt the ferrous metal. Molten ferrous metal flows downwards under gravity into and through the coke bed and may be removed through a tap hole. At least one jet of oxygen is injected into the hot coke bed so as to maintain it at a temperature sufficient to superheat the molten metal. Preferably a fan is operated to dilute with air the combustion gases above the level of the charge in the shaft and thereby create secondary flames. No air blast is supplied to the cupola.
    Type: Grant
    Filed: January 13, 1993
    Date of Patent: April 19, 1994
    Assignee: The BOC Group plc
    Inventor: David R. Westley
  • Patent number: 5295351
    Abstract: In a process integration, particularly with a blast furnace, low grade fuel gas produced by the furnace is compressed and moisturized. The moisturized fuel is burnt using a major part of a compressed air stream to support its combustion. The resulting combustion gases are then expanded with the generation of power. The minor part of the air is separated into oxygen and nitrogen. Oxygen is used in the blast furnace.
    Type: Grant
    Filed: April 6, 1993
    Date of Patent: March 22, 1994
    Assignee: The BOC Group, plc
    Inventor: Thomas Rathbone
  • Patent number: 5294428
    Abstract: A feed gas stream containing at least 60% by volume of hydrogen sulphide is burnt in a first combustion region to form water vapor and sulphur dioxide. Oxygen is employed to support combustion is the region. Thermal reaction then takes place in a thermal reaction region between hydrogen sulphide and sulphur dioxide to form sulphur vapor and water vapor. The resulting gas mixture is then cooled and sulphur vapor is extracted in a condenser. The gas mixture then passes into a second combustion region in which a further portion of the hydrogen sulphide is burnt in the presence of oxygen to form further sulphur dioxide and to adjust the mole ratio of hydrogen sulphide to sulphur dioxide to about 2:1. Further reaction between hydrogen sulphide and sulphur dioxide may be conducted in a further thermal reaction region and in catalytic reactors with further sulphur extraction in further condensers.
    Type: Grant
    Filed: March 2, 1987
    Date of Patent: March 15, 1994
    Assignee: The BOC Group, plc
    Inventor: Richard W. Watson
  • Patent number: 5287704
    Abstract: A method of separating air in which a compressed air stream is divided into first and second subsidiary streams. The first subsidiary air stream is cooled by heat exchange to a temperature suitable for its separation by rectification and introduced into the higher pressure stage of a double rectification column. The second subsidiary air stream is further compressed and then at least part of it is cooled by heat exchange to a first intermediate temperature below ambient temperature but above those temperatures at which the double rectification column operates. The thus cooled second subsidiary air stream is expanded in a first expansion turbine and is withdrawn therefrom at a second intermediate temperature below the first intermediate temperature but above those temperatures at which the double rectification column operates. After withdrawal, the second subsidiary air stream is introduced into a second expansion turbine where it is further expanded.
    Type: Grant
    Filed: November 12, 1992
    Date of Patent: February 22, 1994
    Assignee: The BOC Group, plc
    Inventor: Thomas Rathbone
  • Patent number: 5275742
    Abstract: Oxygen is separated from air by pressure swing adsorption in plant 2. The oxygen is passed through an ozone generator 4. The resulting ozonated oxygen is passed upwardly through a contactor 6 countercurrently to the flow of a side stream of water to be treated with ozone. The side stream containing dissolved ozone flows from the contactor 6 to a mixer 8 in which it is mixed with a main stream of water. The effluent gas from the contactor 6 contains air displaced from the water and undissolved oxygen. It is divided into two parts. One part flows to the pressure swing adsorption plant 2 and is separated therein with the air. The other part is dried by temperature swing adsorption in drier 20 and the resulting dried gas is ozonated in the ozone generator 4 with the oxygen from the plant 2.
    Type: Grant
    Filed: December 11, 1992
    Date of Patent: January 4, 1994
    Assignee: The BOC Group plc
    Inventors: Donald P. Satchell, Jr., Alberto LaCava, Craig C. Ibbetson
  • Patent number: 5269976
    Abstract: A liquid-vapour contact column includes an array of vertically spaced horizontal liquid-vapour contact trays having generally circumferential sides and arrangement of downcomers to conduct liquid from each tray in the array to the tray below. Each tray has gas passages to enable gas to pass into contact with the liquid. A weir is disposed on the floor of at least one downcomer. Each side of the weir is spaced from the corresponding side of the downcomer. This arrangement counteracts a tendency for liquid flowing along the floor of the downcomer to become detached from the sides of the downcomer, such detachment leading to maldistribution of liquid on the tray and hence to less efficient operation of the column.
    Type: Grant
    Filed: November 4, 1992
    Date of Patent: December 14, 1993
    Assignee: The BOC Group, plc
    Inventors: Michael W. Biddulph, Alan C. Burton
  • Patent number: 5268019
    Abstract: Air is taken from the air compressor of a gas turbine including in addition to the compressor a combustion chamber and an expansion turbine. The gas turbine drives an alternator. The air taken from the compressor is cooled in heat exchanger to remove heat of compression therefrom. The air is separated in an air separation plant into oxygen and nitrogen. A stream of oxygen is withdrawn from the plant and used in a blast furnace in which iron is made. The off-gas from the blast furnace is a low grade gaseous fuel. It is compressed in compressor which has interstage cooling to remove at least some of the heat of compression. The compressed fuel gas is passed through the heat exchanger countercurrently to the air stream. The resulting pre-heated fuel gas flows into the combustion chamber of the gas turbine and is burned therein to generate gaseous combustion products that are expanded in the turbine. A nitrogen stream is withdrawn in the air separation plant.
    Type: Grant
    Filed: March 10, 1992
    Date of Patent: December 7, 1993
    Assignee: The BOC Group plc
    Inventor: Thomas Rathbone
  • Patent number: 5268022
    Abstract: A pressure swing adsorption plant for the separation of gas mixtures includes at least one pressure vessel containing an adsorbent bed that is able preferentially to adsorb at least one component of the gas mixture. The pressure vessel has an inlet at its top for the feed gas mixture, an outlet at its bottom for non-adsorbed gas and at least one heat conductive member containing a liquid medium arranged within the bed such that, in operation, heat is able to be conducted by convection through the liquid from a region of maximum temperature at or near the bottom of the bed to a region of minimum temperature at or near the top of the bed.
    Type: Grant
    Filed: March 6, 1992
    Date of Patent: December 7, 1993
    Assignee: The BOC Group plc
    Inventors: Michael E. Garrett, John B. Gardner