Using Reclaimed Water for Cooling Power Plants
Water is a vital resource that has infinite applications and is arguably the most important resource on the planet. A lot of processes in the industrial and power sector use water and then discharge the contaminated water out into the natural environment. In thermal power plants specifically, water is used in the cooling process through heat exchangers and evaporative cooling processes and the hot water is then discharged outside.For this purpose fresh cooling is taken from nearby water sources and used. Today, there have been many developments in technologies that allow power plants to use reclaimed water for this purpose. Reclaimed is basically the water that is supplied by the municipal wastewater treatment plants.
Reclaimed Water for Cooling in Thermal Power Plants
Reclaimed water is an abundant source of usable water which can be effectively used for a wide range of applications. Since it non-potable water, it cannot be used for consumption or for relieving drought-affected areas. The reclaimed water cannot be used as it is for cooling and needs to be treated in order to remove nutrients and corrosive elements. The presence of contaminants can cause rusting, scaling and biofouling on the surfaces of heat exchangers. The growth of germs and other microorganisms on the cooling equipment can cause health hazards and malfunctioning. Diseases such as Legionnaires diseases can be caused by such organisms. Such contaminants can be easily removed using traditional filtering techniques.
Feasibility of using Reclaimed Water for Cooling
There are three main factors which decide the feasibility of using reclaimed water for cooling in thermal power plants.
- Geographical Concerns- There is a geographical limitation of 10 to 25 miles between the wastewater treatment plant and the power plant.
- Technological feasibility- Reclaimed water is generally used for closed-loop cooling tower systems which are used in a lot of thermal power plants. The technological demand here is the water requirement for the closed-loop system.
- Economic requirements- The idea here is to analyze if using the wastewater withdrawal is cost effective when compared with water use from other sources. Investments here in infrastructure include costs for pipelines, investments for on-site water treatment facilities, and cooling systems compatible with treated reclaimed water. These costs must be compared with the existing costs of water management and cooling.
These three factors must be considered before making a decision of using reclaimed water for cooling.
Reclaimed water use is one of the many ways in which thermal power plants can become environmentally friendly and reduce their carbon footprint. Some of the other key areas of water conservation in power plants are ash handling, coal handling and ETP.
The important thing here is to develop an attitude of conservation and constantly remain vigilant regarding the latest technologies that are available for improving process efficiencies and recycling resources. Recycling and reuse systems are being developed that can utilize all forms of effluents, emissions and slags that are generated in the operations of a thermal power plant.