关键词: 火电厂, 低压省煤器, 余热, 排汽量, 有效利用, 冷源损失

Abstract: In order to evaluate the effectiveness of utilizing the heat absorbed by the low-pressure economizer, based on the fundamental principles of the equivalent enthalpy drop method, a general computation model is established for the influence of extraction and injection of the condensate in the low-pressure heating system on the exhaust volume of the steam turbine. Then, a general model is derived to compute the influence of the low-pressure economizer on the steam turbine exhaust volume when operated under various connection modes. Taking a domestic 330 MW unit as an example, using the computation model proposed in this paper, the increments of the steam exhaust volume and exhaust losses under two different operating conditions are obtained respectively, which shows that only about 10% of the thermal energy absorbed in the low-pressure economizer is reused by the steam turbine to produce power, while the rest of the heat eventually becomes part of cold source loss.

Key words: thermal power plant, low-pressure economizer, exhaust heat, exhaust volume, effective utilization, cold source loss