Abstract: A method and an installation for the utilization of residual heat in pulp mills, where spent cooking liquor is evaporated with vapor in a multi-stage evaporator. The installation for carrying out the method comprises a number of evaporation steps connected in such a way, possibly by arranging several steps or groups of steps in parallel, that the outlet vapor from the last step or steps holds saturation pressure immediately below atmospheric pressure, a heat exchanger for condensation of the outlet vapor from the evaporation steps during evaporation of a fluid which, for the corresponding amount of heat, at the actual heat exchange temperature, has a markedly smaller volume than the outlet vapor, a turbine for expansion of the fluid vapor, a condenser for condensing the outlet vapor from the turbine, and a pump for increasing the pressure of the condensed fluid to a pressure suitable for return to the heat exchanger.