Abstract: Process for causticizing a water solution containing alkali carbonate with calcium oxide and hydroxide by bringing the water solution containing alkali carbonate into contact with the calcium oxide or hydroxide and by separating the alkali hydroxide solution arisen in the causticizing from the calcium carbonate precipitate. The water solution containing alkali carbonate is conducted through a bed which has been formed by mixing calcium oxide and calcium carbonate in the causticized alkali solution and by removing the excess alkali solution.

Abstract: A process for continuous digestion of wood chips which are passed through a heating zone, a digesting zone and a cooling zone in contact with cooking liquor is disclosed. In this process the wood chips are fed into and the liquid phase removed from the input end of the heating zone in such relative quantities that their heat-capacity flows are of approximately the same order of magnitude.

Abstract: The invention relates to a method for evaporation of a solution in a recompression evaporation plant. The solution is evaporated first in known manner by indirect transfer of heat from the recompressed vapor through condensation of said vapor in one or more evaporation units. After pre-evaporation in this fashion the solution is finally evaporated by direct transfer of heat from the overheated vapor which is obtained by recompression of the vapor formed in evaporation. According to the invention this final evaporation is achieved by mixing the solution in finely-divided form with the overheated vapor and then after thermodynamic equilibrium between the vapor and liquid phases has been substantially attained separating the solution from the vapor. The solution thereby obtained can be further evaporated without the addition of heat but with a reduction of pressure by means of conducting it to an expansion vessel which is connected by a vapor line to the suction line of the compressor.