Feedwater Heater

Definition

A feedwater heater is a device used in thermal power plants to preheat the water before it enters the boiler, improving the efficiency of the steam cycle. By recovering waste heat from the exhaust steam of the turbine, these heaters reduce the overall energy requirement for heating water, which enhances the performance of the Rankine cycle and ultimately leads to increased power generation and reduced fuel consumption.

5 Must Know Facts For Your Next Test

1. Feedwater heaters are classified into two main types: open and closed. Open heaters allow steam to mix with water, while closed heaters use a heat exchanger for indirect heating.
2. The use of feedwater heaters can increase the thermal efficiency of a power plant by as much as 10-15%, depending on the specific configuration and operating conditions.
3. In a typical setup, feedwater heaters are placed between the condenser and the boiler to maximize heat recovery from the exhaust steam.
4. By preheating the feedwater, these heaters reduce the amount of fuel needed to reach operating temperatures in the boiler, leading to cost savings and lower emissions.
5. The integration of feedwater heaters in a power plant can also lead to extended equipment life due to reduced thermal stress on boiler components.

Review Questions

• How does a feedwater heater improve the overall efficiency of a Rankine cycle?
  • A feedwater heater improves the efficiency of a Rankine cycle by preheating the water before it enters the boiler, which reduces the energy required to convert it into steam. By recovering waste heat from the exhaust steam of the turbine, it ensures that less fuel is needed to reach desired temperatures. This process minimizes thermal losses and maximizes energy utilization within the system.
• What are the key differences between open and closed feedwater heaters, and how do these differences impact their application in thermal power plants?
  • Open feedwater heaters allow steam to directly mix with water for heating, which can lead to some loss of condensate quality but allows for effective heat transfer. Closed feedwater heaters, on the other hand, utilize heat exchangers to transfer energy without mixing, maintaining better condensate quality. The choice between them impacts efficiency, maintenance requirements, and overall performance in specific applications within thermal power plants.
• Evaluate the significance of implementing feedwater heaters in modern thermal power plants regarding sustainability and operational costs.
  • Implementing feedwater heaters in modern thermal power plants plays a crucial role in enhancing sustainability by reducing fuel consumption and emissions through improved thermal efficiency. This technology not only contributes to operational cost savings due to lower fuel requirements but also supports compliance with environmental regulations. As energy efficiency becomes increasingly important in addressing climate change, feedwater heaters represent a practical solution for optimizing resource utilization while minimizing ecological impact.

Related terms

Thermal Efficiency: The ratio of the work output of a thermodynamic cycle to the heat input, indicating how effectively a system converts heat energy into work.

Condensate: The liquid formed when steam cools and condenses back into water, typically collected and returned to the feedwater system.

Regenerative Rankine Cycle:

A variation of the Rankine cycle that incorporates feedwater heaters to improve thermal efficiency by utilizing waste heat.