Abstract: The invention is concerned with a process of the type in which the air to be treated, from which water and CO.sub.2 have been removed and which has been cooled at about its dew point, is injected at the base of the mean pressure column of the double column. A first fraction of rich liquid, withdrawn from the bottom of the mean pressure column is expanded and sent into a head condenser of a column for the production of impure argon connected to the low pressure column of the double column. A second fraction of rich liquid, withdrawn from the lower portion of the mean pressure column, is expanded and sent as reflux into the low pressure column. According to the invention, a second fraction of rich liquid is withdrawn from an intermediate point of the mean pressure column and a residual gas from the apparatus is formed from at least a portion of the rich liquid withdrawn from the bottom of the mean pressure column.

Abstract: The column for the production of impure argon (2) is surmounted by an auxiliary column section (9) which is cooled to produce reflux by vaporizing poor liquid withdrawn from the head portion of the mean pressure column (3) and expanded. Application to the addition of an argon side column to an air distillation double column.

Abstract: Gaseous oxygen is produced under a medium pressure which is higher than atmospheric pressure, and lower than a so-called high pressure. The medium pressure may also vary with time after which gaseous oxygen is brought to the high pressure. Each of the adsorbers of a high pressure PSA (Pressure swing Adsorption) adsorption device, undergoes a cycle including the following stage: (a) a stage of first pressure surge from a low pressure of the low pressure cycle to the medium pressure, during which oxygen under a medium pressure is introduced at a first end or outlet end, of the adsorber; (b) a stage of second pressure surge up to the high pressure; (c) a stage of production under high pressure, during which a gas substantially below the high pressure containing at least one component which is more easily adsorbed than oxygen, is introduced through a second end, or inlet end of the adsorber the gas being for example air, the first end being open; and (d) a stage of decompression to the low pressure of the cycle.

Abstract: These gases, specially adapted to the need of CO.sub.2 lasers, have a total purity less than 99.995%, a water content lower than 5 vpm and a total hydrocarbon content lower than 5 vpm.

Abstract: The air distillation double column (1,2) includes an apparatus for vaporizing oxygen and condensing nitrogen which comprises on one hand a running type main heat exchanger (7) which is partially immersed during stoppage of the equipment and on the other hand an auxiliary heat exchanger (20) which alone is responsible for liquid vaporization when the equipment is restarted.

Abstract: Heat treating metals by continuous longitudinal passage of metallic pieces in an elongated treating zone under controlled atmosphere having a high temperature upstream end where the controlled atmosphere comprises nitrogen and reducing chemical substances, such as hydrogen, possibly carbon monoxide, and a downstream cooling end under an atmosphere essentially formed by introducing nitrogen. In the high temperature upstream end, the nitrogen which constitutes the atmosphere is supplied by introducing nitrogen with a residual oxygen content not exceeding 5%, the reducing chemical substances being present at any moment in amounts at least sufficient to eliminate oxygen introduced with nitrogen. The nitrogen introduced in the downstream cooling end is substantially free of oxygen. Application of the process to the annealing of metallic pieces.

Abstract: An annealing treatment in a continuous furnace in which a flow of dense inert gas is injected in a rising duct and a descending duct, these flows being regulated by the analysis of hydrogen detected by a pressure controller acting on valves to achieve a minimum escape of hydrogen.

Abstract: Gaseous oxygen to be cooled passes through an exchanger which is cooled with compressed liquid nitrogen, at least a portion of the vaporized nitrogen which is warmed up in the exchanger being treated in a turbine and thereafter reintroduced into the exchanger. Application for example to the storage in liquid form of excess oxygen under pressure conveyed by a distribution network with variable load.

Abstract: Process for thermal treatment of metals by passage of metallic pieces into an elongated zone under a controlled atmosphere, having an upstream section at an elevated temperature, where the controlled atmosphere comprises nitrogen and reductive chemicals, particularly hydrogen, possibly carbon monoxide; and a downstream section at a lower temperature under a controlled atmosphere. The invention is characterized by the fact that in the upstream section at an elevated temperature, the atmosphere comprises nitrogen having a residual content of oxygen between 0.5% and 5% produced by separation of air using permeation or adsorption techniques. The reductive chemicals are present at all times in a content at least sufficient to eliminate the oxygen admitted with the nitrogen.

Abstract: Tundish for continous casting of steel, of the type comprising a permanent refractory, cast on a frame of sheet metal defining the outer wall of the tundish and on which a refractory wear has been laid. In the body of the permanent refractory, there is provided a gas duct which penetrates into the permanent refractory at the level of the upper edge of the tundish and extends to the bottom of the tundish into a gas distribution chamber, which is covered with a surface distributed gas permeable plate. Application to the continuous casting of steels for tundish between casting ladle and ingot molds.

Abstract: This invention relates to a process for producing gas mixtures by a plurality of dilution steps of a high concentration standard gas with a high purity diluent gas. According to the invention, as soon as the high purity diluent gas is generated, no further contaminants such as gaseous impurities are added during the further mixing of diluting steps of the process. Only orifices or needle valves are used in the mixing or diluting lines while mass flow controllers and pressure regulators are placed upstream, at the output of the gas sources and/or downstream, i.e. in the gas-venting lines. The invention particularly applies to trace analysis of gas with Atmospheric Pressure Ionization Mass Spectrometry.

Abstract: The invention relates to a process of making a high purity silicide target comprising the steps of providing a substrate in a CVD enclosure, evacuating said enclosure up to a pressure P1 which is at least equal to or smaller than 5.times.10.sup.-5 Torr, heating the substrate at a temperature T1, which is at least equal to or greater than 20.degree. C., injecting in said enclosure a refractory metal halide MXm having a purity, as far as metallic impurities are concerned, greater than 5N (99,999%) and a silicon hydride having a purity, as far as metallic impurities are concerned, greater than 6N (99,9999%) setting the pressure in the enclosure between about 0.01 Torr and the atmospheric pressure while maintaining the temperature in the CVD enclosure between about 20.degree. C.

Abstract: Part of the hydrogen from the gas treated, which is for example a residual gas from petroleum refinery, is first removed. The remaining mixture is introduced at an intermediate level of a distillation column which includes a head condenser operating at a temperature TF of the order of -40.degree. C. or more. The hydrogen content of said remaining mixture is selected so that the dew point of the residual gas which is removed at the top of the column is slightly higher than the temperature TF. The heavy hydrocarbons are collected at the base of the column.

Abstract: The invention is exclusively concerned with heat treatments before hardening, of metallic pieces, by cementation, carbonitridation and heating. The process concerns the feeding of a non muffle heat treatment furnace with various components including nitrogen which is produced by an adsorption or selective permeation generator and which has a residual oxygen content of the order of 2%. According to the invention, after the furnace has ceased to be in operation for a substantial period of time, it is reconditioned by injecting purer nitrogen which has a residual oxygen content lower than 0.3% and which is produced by said generator, adjusted at a lower extraction rate.

Abstract: According to the process, there is maintained in a conduit (3), on the downstream side of a valve (5), up to the vicinity of the point A of injection of the CO.sub.2, an intermediate pressure (PI) higher than the pressure (PT) of the triple point of the CO.sub.2. Application in the treatment of waste waters or the deep freezing of food.

Abstract: The gas which comes from a source passes through a regulating valve, then through a heat exchanger and is sent to the network through a production duct. The heat exchanger thus acts as a muffler. Application to the supplying of gas from air separation.

Abstract: A method for forming a helical waveguide uses a deposit screen such as tape to prevent the deposit of unwanted material between the turns of the helix. The waveguide is formed by electroplating of nickel on a mandrel. The mandrel has raised portions similar to a screw on which the waveguide is formed. The deposit screen is placed in the recessed areas between the raised areas on the mandrel to prevent the mandrel from being plated in these areas. This prevents the turns of the helix from touching each other. The resultant helix is easily removed without damage to the waveguide or mandrel.

Abstract: The invention relates to a process for condensing at least one epoxide on at least one cyclic anhydride of a dicarboxylic acid in the presence of a catalyst consisting of at least one titanium nitrogenous complex of the formula (I) Ti(OR.sup.1).sub.m (OR.sup.2 ).sub.n (OR.sup.2 ).sub.p Lg in which R.sup.1, R.sup.2 and R.sup.3 each independently represents one hydrocarbon group, L represents the remainder of a nitrogenous compound, the sum of m+n+p+q is 4, q is an integer from 1 to 4 and m, n and p are independently each 0 or 1. The process allows for obtaining a perfectly alternating polyester.

Abstract: Process of restructuring a group of finely divided particles, of granulometries lower than 100 microns, wherein the particles to be restructured are placed in a bath of cryogenic liquid which is inert with respect to the particles, the operation of restructuring is allowed to proceed after which the cryogenic liquid is withdrawn for example by evaporation. Applications to the production of metallic alloys, special polymers, paints, inks, carbon black, special ceramics and pharmaceutical or food products.

Abstract: A process for condensing at least one aliphatic epoxide having at least 8 atoms of carbon in its molecule on at least one cyclic anhydride of a dicarboxylic acid in the presence of a catalyst consisting of at least one titanium complex of general formula (I) Ti(OR).sub.2 (L).sub.2 in which each R group independently represents one hydrocarbon group with 1 to 10 atoms of carbon and each L group represents a ligand of the diketonic beta type or of the keto-ester beta.