Abstract: A process for purifying a polluted fluid which comprises heating the polluted fluid and evaporating the components of said polluted fluid which are more volatile while simultaneously concentrating the pollutants into a residue, introducing said residue to a combustion chamber where it is at least partially burned and introducing the heat of combustion as the only source of heat to the evaporation stage of the process.

Abstract: A process and apparatus for purifying waste water which comprises introducing said waste water into a separation zone, removing a portion of the impurities recovered from said separation zone, and concentrating said impurities by their introduction into an evaporation system to form a still fluid residue and remaining impurities composed of impurities in gaseous and vapor form together with waste vapors, transferring said remaining impurities to an oxidation chamber, and supplying said oxidation chamber with heat and air, thereby oxidizing said remaining impurities through spontaneous combustion, wherein the proportion of the low boiling-point impurities in the waste water introduced into the separation zone is adjusted to a predetermined value.

Abstract: The heat transfer apparatus comprises a storage reservoir containing salt as a heat carrier with a heater connected into the reservoir to heat the heat carrier so as to maintain it above the freezing point. The heater may comprise an electric heater or a fluid which is circulated for example from a separate heat exchanger. An intermediate heat exchanger is connected so that the salt is circulated therethrough and in heat transfer relationship to an intermediate heat carrier such as a metal alloy which is circulated from a consumption heat exchanger. The intermediate heat exchanger is in heat exchange relationship with a consumption heat carrier.

Abstract: A corrosive liquid such as sulphuric acid is concentrated using two spaced concentric tubes. A film of the acid flows down the inside of the inner tube and hot flue gases contact the outside of the outer tube. Advantageously, the inner tube transmits radiant energy, e.g. is made of quartz, so the outer tube heats the inner tube by radiation. This absence of mechanical stress on the inner tube increases its life. The water vapor is taken off at the top of the inner tube and concentrated solution at the bottom. If desired, the tubes could be reversed with the flue gases going through the inner tube and the outer tube being of quartz with the liquid flowing on its outside.

Abstract: A multi-stage apparatus suited for concentrating sulphuric acid comprising at least one high temperature stage and one low temperature stage, the high temperature stage including a surrounding wall defining a flue gas channel, means for delivering hot flue gas to said channel, and means for withdrawing from said channel cooled flue gas, the flue gas heating said surrounding wall which in turn imparts heat to material to be heated thereby, the low temperature stage including a heat exchanger with a first flow path for a heating agent and a second flow path for a material to be heated thereby, means for supplying the said second flow path material to be heated, means for withdrawing from said second flow path material after having been heated therein, and means for withdrawing from said first flow path spent heating agent, the means for withdrawing cooled flue gas from said flue channel of said high temperature stage forwarding heat from said cooled flue gas to said first flow path of said low temperature stage

Abstract: In the processing of a corrosive liquid mixture, such as 50 to 80% aqueous sulfuric acid, by its passage over one surface of a wall of inert heat resistant material, and heating the other surface of said wall, thereby to evaporate from said corrosive liquid mixture the more volatile component thereof, the improvement which comprises heating said wall by contact with an inert liquid material, and heating said inert liquid material indirectly through heat exchange with a normally solid molten material. Desirably the wall of inert material is a pipe surrounded by a molten metal in a first annular jacket and a molten salt in a second annular jacket.

Abstract: In the processing of a corrosive liquid mixture, such as 50 to 80% aqueous sulfuric acid, by its passage over one surface of a wall of inert heat resistant material, and heating the other surface of said wall, thereby to evaporate from said corrosive liquid mixture the more volatile component thereof, the improvement which comprises heating said wall by contact with an inert liquid material, and heating said inert liquid material indirectly through heat exchange with a normally solid molten material. Desirably the wall of inert material is a pipe surrounded by a molten metal in a first annular jacket and a molten salt in a second annular jacket.