Introduction

Thermal power plants use water for various purposes such as steam production, cooling, and ash handling. Water consumption in a thermal power plant is an important parameter to measure its efficiency as well as its impact on the environment. In this article, we will discuss how to calculate water consumption in a thermal power plant.

Water Consumption for Steam Production

The primary use of water in a thermal power plant is for steam production. The amount of water required for steam production depends on the design and efficiency of the plant. For example, a plant with a higher efficiency will require less water for steam production. The water consumption for steam production can be calculated using the following formula:

Water Consumption for Steam Production (m3/hr) = Steam Flow Rate (TPH) x Specific Enthalpy of Steam (kJ/kg) / (Specific Heat of Water (kJ/kg.K) x Boiler Efficiency)

Where TPH stands for tons per hour.

Water Consumption for Cooling

The second major use of water in a thermal power plant is for cooling purposes. The amount of water required for cooling depends on the type of cooling system used in the plant. There are two types of cooling methods used in thermal power plants – once-through and closed-loop cooling systems.

In a once-through cooling system, the water is pumped from a nearby source, used to cool the condenser, and then discharged back into the source. The water consumption in a once-through cooling system can be calculated using the following formula:

Water Consumption for Once-through Cooling (m3/hr) = Circulating Water Flow Rate (m3/hr) x Cooling Water Temperature Rise (°C)

In a closed-loop cooling system, the water is circulated through a cooling tower, which cools the water by evaporation. The water consumption in a closed-loop cooling system can be calculated using the following formula:

Water Consumption for Closed-loop Cooling (m3/hr) = Evaporation Loss (m3/hr) + Drift Loss (m3/hr) + Blowdown Loss (m3/hr)

Where evaporation loss is the water lost due to evaporation, drift loss is the water lost due to wind and splash, and blowdown loss is the water lost due to the removal of impurities.

Water Consumption for Ash Handling

The third major use of water in a thermal power plant is for ash handling. Ash is produced when coal is burned in the boiler. The ash is removed from the boiler and transported to ash ponds for storage. Water is used to transport the ash through the pipes and to maintain the ash pond. The water consumption for ash handling can be calculated using the following formula:

Water Consumption for Ash Handling (m3/hr) = Ash Disposal Rate (TPH) x Total Moisture in Ash (%) / (Water Content in Ash (%) + 100)

Where TPH stands for tons per hour.

Conclusion

Water consumption is an important parameter to measure the efficiency of a thermal power plant. The calculation of water consumption for steam production, cooling, and ash handling can help in optimizing the water usage in the plant. By reducing the water consumption, a plant can save cost and reduce its impact on the environment.