Energy efficient lye recovery system

Large quantities of highly alkaline liquid wastes (with pH exceeding 12) have been produced as a result of soda lye application in many industries all around the world. From the "cleaner production" and "sustainable development" points of view the effective recycling and recovery of lye is the best solution because the working life of lye can be prolonged and the volume of hazardous waste generated can be reduced. The recovery of lye from waste waters results with the advantages such as savings of firesh lye and neutralizers, increasing of energy efficiency including heat recovery and lower environmental pollution. The purpose of this paper is to investigate the influence of the number of stages in the multiple effect evaporation system on the costs and process energy efficiency. The mathematical model for the simulation of an evaporation system, based on material and energy balance equations, is derived. Using the simulation model programmed for computer the calculations are made for real process data from domestic industry. The calculation results are shown on figures in general and specific forms and are discussed.