Research on varying condition characteristic of feedwater heater considering liquid level

In this paper, a mathematical model of varying condition is established for the three-section heater based on dimensional analysis, then with the combination of the derivation of heat transfer coefficient in the drain cooler section, the model of operating characteristic for the heater at low liquid level is proposed. Taking #1 high pressure feedwater heater of a 330 MW turbine as example, the terminal temperature difference at both normal liquid level and low liquid level and the change of the heat transfer condition in the drain cooler section at low liquid level can be calculated respectively by the proposed model. By comparison with the test data the accuracy of the model is verified. In addition, the influence of liquid level and load on terminal temperature difference is analyzed quantitatively, and the secure liquid level and economic liquid level are reset. The results show that the study can provide a reference for the timely adjustment of the liquid level in actual operation.