REVERSE-OSMOSIS DESALINATION BY WASTE HEAT ABSORPTION POWER CYCLE

A waste heat bottoming steam power cycle is proposed using conventional absorption machines. A lithium-water absorption machine is modified with a steam turbine replacing the condenser, the pressure reducing valve and the evaporator in the conventional LiBr/H//2O machine. The generator is fired by the waste heat and the steam generated is superheated before being admitted to the steam turbine. Exhaust steam from the turbine is sent to the absorber of the LiBr/H//2O machine. Thus the steam expansion is controlled by the absorber equilibrium conditions rather than by the cooling water temperature. The proposed cycle is analyzed using the waste heat of four gas turbines and the results are compared with the existing Rankine bottoming cycle as well as with other waste heat recovery systems. Between a generator pressure of 150 kPa and an absorber equilibrium pressure of 3. 2 kPa, steam expands in the turbine and the power output is used to drive a reverse osmosis plant.