Research PaperDevelopment of a model to evaluate the water level impact on drain cooling in horizontal high pressure feedwater heaters

- A model for a three-zone feedwater heater is suggested then tested.
- Model is not limited to any specified sets of operating conditions and geometry.
- Characteristics of a typical heater is analyzed.
- Performance of heater is most sensitive to level changes under full load condition.

Feedwater heaters play an important role in improving power plant thermal efficiency. High pressure feedwater heaters are generally of shell and tube type of heat exchangers which have three shrouded zones in the shell. In present study, a mathematical model is suggested for performance evaluation of a three-zone feedwater heater. Proposed model is capable of predicting the effects of variation in liquid level and load condition. The model is verified by experimental results existing in literature. Then impact of increase or decrease of liquid level on performance characteristics are evaluated for a typical horizontal high pressure feedwater heater. The influence of water level and load on drain cooler approach is analyzed quantitatively. Results show sharp variation in drain cooler approach in low water level condition. It is also shown that at full load condition, heater is more sensitive to liquid level changes.