IT IS EXPECTED THAT THE COMBINATION OF THE ABSORPTION AND REGENERATION EVAPORATORS WILL RESULT IN A REDUCTION OF STEAM CONSUMPTION IN THE RANGE OF 30 - 40 % AS COMPARED TO THE CONSUMPTION IN CONVENTIONAL MULTIPLE EFFECT EVAPORATORS. THE AIM OF THE PROGRAMME IS TO DEMONSTRATE THE OPERATIONAL POSSIBILITIES OF THE SYSTEM AND TO EVALUATE ITS ENERGETIC AND ECONOMIC ASPECTS. THE VARIOUS PARAMETERS ENTERING THE DESIGN OF SIMILAR SYSTEM WILL ALSO BE STUDIED.
An absorption driven evaporator coupled to a conventional two effect evaporator, which was used for the regeneration of the absorptive solution, was constructed and studied. The feasibility of absorption driven multiple effect evaporators was demonstrated experimentally using, a four effect absorption driven falling film evaporator coupled with a two effect steam heated regenerator. The energy consumption of an experimental unit was measured and compared with the energy requirements of the same unit when operated as a conventional steam heated evaporator. It was shown that the energy savings were between 30% and 45%,depending mainly on; the efficiency of the heat exchanger used in the regenerator for the recovery of sensible heat from the solution, the heat losses in the regenerator, the flow rate of the solution and the overall heat transfer coefficient of the absorber. A preliminary economic assessment shows that the payback period of a commercial absorption driven evaporator could be from 0.99 to 3.86 years for a range of economic and technical scenarios, while the discounted cash flow rate of return could be from 2.5 to 49%.
THE PROGRAMME INVOLVES THE CONSTRUCTION, OPERATION AND STUDY OF A STEAM DRIVEN MULTIPLE EFFECT EVAPORATOR THE FIRST EFFECT OF WHICH OPERATES THROUGH THE PROCESS OF ABSORPTION. IN THE FIRST EFFECT A SOLUTION OF HYGROSCOPIC SALT IS EMPLOYED AS HEATING MEDIUM WHICH ABSORBS THE WATER VAPOURS PRODUCED IN THE LAST EFFECT. THE ABOVE EVAPORATOR IS COMBINED WITH A CONVENTIONAL EVAPORATOR FOR THE REGENERATION OF THE HYGROSCOPIC SOLUTION THROUGH THE USE OF STEAM.