Abstract: An air separation process wherein a nitrogen enriched fraction is withdrawn from the distillation column, a portion of which is compressed and recycled through the lowest positioned reboiler in the column and directed to an upper portion of the column as reflux.

Abstract: In this process of the liquid nitrogen/rich liquid HPN swing type, the connection between the head of the column (4) and the liquid nitrogen holding tank (7) is effected, for the two flow directions of the liquid nitrogen, by a single conduit (12) equipped with a pressure reducing device (13). The direction and the flow rate of the liquid nitrogen flow are controlled by the variations of the pressure of the column, and the holding tanks of liquid nitrogen and rich liquid are maintained at constant pressures.

Abstract: Indirect heat exchanger, of the type comprising a series of parallel plates (7) delimiting between themselves passages (8A, 8B; 28, 42, 60) of generally plate form containing undulant spacers (9; 32, 34, 36, 37, 44, 47, 48, 53 to 56). A first assembly (8A; 28, 60) of these passages constitutes thermal exchange passages having structure (3 to 5; 39 to 41, 51) for inlet and outlet of fluids adapted to exchange heat with each other. Over at least a portion of its length and of its width, the exchanger has added passages (8B; 42), in reduced or no heat exchange relation with the thermal exchange passages (8A; 28, 60) and provided to fulfill at least one function in addition to the exchange of heat, namely a function of storing liquid and/or recirculation of liquid and/or liquid-vapor separation.

Abstract: A column for production of nitrogen by the distillation of air, adapted to produce high purity nitrogen at its head, is associated with an external source of medium purity liquid nitrogen that is fitted with a device for the liquid phase adsorption of carbon monoxide, and with a reservoir for the storage of high purity liquid nitrogen. The column produces medium purity gaseous nitrogen and high purity gaseous nitrogen by direct withdrawals, optionally supplemented by vaporization of liquid nitrogen.

Abstract: A process for producing gaseous nitrogen from a mixture to be treated in a distillation column, said mixture comprising nitrogen and oxygen, said process comprising the steps of:a) compressing the mixture to be treated to a pressure at least equal to the column pressure;b) cooling the compressed gas mixture and subjecting at least a first portion of said cooled mixture to expansion through a turbine to produce the required refrigeration and thereafter fractionated distillation in the column to obtain at the bottom of the column, an oxygen-enriched fraction and, at the top of the column, a nitrogen-enriched fraction,c) drawing off at least a portion of the nitrogen-enriched fraction as nitrogen product;d) compressing the remaining portion of the nitrogen-enriched fraction;e) recycling at least a portion of the compressed remaining portion of the nitrogen-enriched fraction to the bottom reboiler of the column where it condenses to provide reboil for the column;f) introducing at least a portion of the condensed

Abstract: The conduits (1-4) of length L have a linear section S.sub.1 and contain a volumetric flow rate of nitrogen Q such that, to obtain a molar concentration of impurities upon out-gassing less than C.sub.max, Q/S.sub.1 is not less than 9.5.times.10.sup.-9 L/C.sub.max. The conduits are of stainless steel with a low carbon content, not electropolished and/or chemically treated. The joints (6, 7, 9, 11) between the conduits and/or the active members (5) are maintained externally in a neutral protective atmosphere confined in a sealed casing (8, 9 . . . ) Application particularly to electronic industries.

Abstract: The invention aims at preventing the risks of deformation and breaking down of the heat exchanger which is part of a plant for the batch treatment of fluids, of the type in which, during active periods which are separated from one another by rest periods, at least one refrigerating fluid is allowed to circulate in first ducts of the exchanger, from the cold end to the hot end of the latter, and at least one calorigenic fluid is circulated in second ducts of the exchanger, from the hot end to the cold end of the latter, characterized in that, during rest periods, heat is introduced at the hot end and cold is introduced at the cold end of the exchanger so as to maintain these two ends at temperatures which are relatively close to those corresponding to the active periods, at least one of these two inputs being supplied by means of a reserve fluid of the plant.

Abstract: The article of which the verticality is critical, for example a distillation column disposed in a closed envelope, is associated with an indicator of verticality comprising a suspended mass and a locating ring. The envelope, which contains the various inner articles, is placed on a base by means of supports and its inclination with respect to the base is adjusted by controlling the relative position of the mass with respect to the ring. Application for example to cold boxes for the in situ production of gas from air.

Abstract: As soon as the apparatus is started, a flow of liquid nitrogen which is at least equal to the nominal flow of gaseous nitrogen is introduced in the head portion of the column, then the flow of liquid nitrogen is adjusted to a small fraction of this nominal flow. Application to the production of a flow of gaseous nitrogen which is variable and moderate.

Abstract: According to this process, compressed air is cooled and purified by adsorption by passing same in a first direction through a mass of adsorbent material (8), then a residual gas from the distillation apparatus passes in opposite direction through this mass to regenerate same. During the entire regeneration, the residual gas is at a constant regeneration temperature which is between the temperature of the air entering into the mass of adsorbent material and at a temperature which is about 50.degree. C. above this temperature.