Minimize the environmental impacts of the thermal dischage at power stations

Power plants take fresh water from waterways for cooling purposes thendischarge it back to the waterways in almost the same quantity but withtemperature rise about 10 QC above ambient. Egypt needs annually about 7milliards rrr’ from Nile River and 3.7 milliards m3 from the seas for coolingpurposes of thirty five power plants.Thermal water has ecological and hydraulic impacts. The ecological impacts include a reduction in the ability of water to hold dissolved oxygen that is necessary for fish life also thermal water change the quality of water. The hydraulic impacts include recirculation/transport of thermal water from the outlet of the plant to the inlet of the same/different plant.The objective of this research is to find a scheme to minimize the impacts ofthe plants effluent by using multi port diffusers to discharge ambient water atthe plants outlet channel to be mixed with thermal discharge in order toachieve effective reduction of the outlet water temperature before discharge thermal water to the river to comply with law 48/1982 which specified that the maximum allowable temperature rise above ambient water is 5 QC and amaximum discharge temperature is 35 QC.The laboratory study using a physical model investigates the sensitivity of the temperature reduction and wave height due to the change in sevendimensionless parameters and a formula developed to predict the temperaturereduction and the formed wave height in accep accuracy.The new technique of using diffusers applied at Nubaria power plant physicalmodel which has narrow channel and thermal discharge reaches to other sidebank. The new technique reduced the water temperature by amount of 20 % to30 % than using the ordinary outlet which comply with law 48/1982. The newtechnique used at numerical model of Kureimat power plant and succeeded inreducing the thermal spreading in the Nile River.