Final answer:
Open feedwater heaters in steam power plants are used to heat boiler feedwater, which improves the thermal efficiency of the plant and reduces operational costs.
Step-by-step explanation:
In steam power plants, open feedwater heaters are primarily utilized to heat boiler feedwater. The purpose of these heaters is to precondition the feedwater before it enters the boiler where it is turned into steam. By increasing the temperature of the feedwater, thermal stress on the boiler is reduced, and the overall thermal efficiency of the power plant is improved. Once the feedwater absorbs heat, either from the turbine exhaust steam in a regenerative cycle or from another external source, the preheated water is then fed into the boiler for further heating and conversion into steam that will drive the turbines.
Heating the feedwater is a crucial step in maintaining the efficiency of the steam cycle. By preheating, the amount of fuel required to produce steam is reduced, leading to fuel savings and lower operational costs. Additionally, this process helps in avoiding the thermal shock that the boiler might experience if cold water were introduced directly. Open feedwater heaters play a significant role in optimizing the cycle by absorbing waste heat from different stages of the turbine, thus leveraging the heat that would otherwise be discarded into the environment. Ultimately, this boosts the efficiency and economic performance of the power generation process.