Economic Benefits Analysis Of Technical Innovation Of Double-rotor And High Back Pressure Application In 145MW Power Plant

In recent years, according to the requirements of energy conservation and emissions reduction and the "developing large units and suppressing small ones" policy, a large number of small-scale power plants and heating units have been limited output or shut down, because of their high energy consumption, poor economic performance, and failure to meeting environmental protection requirements. However, as the urban population and residential area continuously increase, heating load demand for urban residents during the winter has also increased year by year, an increasing number of thermal power units enter the heating market to meet the heating requirements of the people’s livelihood. Under this situation, Huadian Zhangqiu Power Plant (hereinafter referred to as the Zhangqiu company) actively coordinates with local government, and develops the heating market of thermal power unit. At the same time, the company, in view of the actual situation, actively increases capital and staff input, and energetically explore more energy-efficient heating experience.Zhangqiu company’s #2 unit boiler is SG-435/13.7-M760 ultrahigh pressure, intermediate reheat, natural circulation drum boiler, made in Shanghai Boiler Works. The boiler is designed to be balanced draft, (?) type, outdoor layout, and corner tangential firing. Its rated evaporation rate is 435 t/h, and boiler efficiency under BMCR design condition is 91%. The steam turbine is N145-13.24/535/535 ultrahigh pressure unit, made in Shanghai Turbine Works. Its rated electric load is 145 MW, adopting once intermediate reheat, double casing and double flow, steam extraction and condensing thermal circulation system. The most heat loss in the unit thermal cycle is cold source loss from circulating water in the cold water tower. In order to use these heat effectively, Zhangqiu company actively explored the heating technology reform using steam turbine’s high back pressure circulating water, and firstly tried double rotor swapping circulating water heating reform of low pressure cylinder at high back pressure. To recycle the heat of cycling water in the winter, the company transformed the turbine blade and baffle, condenser, shaft seal heater, the heating and heat exchanger station. As a heating source, the recycled heat was supplied to the urban residents to meet the residents’ heating requirements, and finally that would achieve the purpose of waste heat utilization, energy conservation and emissions reduction. During the winter heating period, the running unit’s coal consumption rate fell to 145 g/kWh from 321 g/kWh under simple condensing steam situation, and the falling range was 176 g/kWh. Reversely, since the cold source loss from turbine exhaust steam was completely used, the thermal efficiency of steam turbine was increased to 97% from 43%. Both operational economy and safety design of the unit meet the desired effect, and its energy saving effect is remarkable, which contributes to the task of energy conservation and emissions reduction and residents’heating.This selected topic made a heating power market analysis based on heating demand situation and the heating ability of heating units around the east of Jinan, and did a feasibility study about Zhangqiu company’s #2 unit of high back pressure, dual-rotor interchangeable transformation. Tracking records of the whole process was made including the design scheme, equipment reformation construction, and commissioning. Also, the topic enumerated the problems and difficulties existing in the reform process, and gave the corresponding solutions. At the same time, to make thermal performance test scheme and collect the thermal test data under typical operating conditions, comprehensive observation and analysis about the unit operated at the high back pressure were made, during heating period. Based on the local standard for energy consumption calculation regulations of cogeneration units, the topic calculated and analyzed the thermal performance, evaluated the unit’s heat economy running under different working conditions, then listed the main economic indicators, finally got the recovery period of transformation investment to ensure the most economical way of operation adjustment heating of the unit. This could provide an example of reform scheme and operation adjustment experience for the transformation of large-scale unit, adopting the technology of dual-rotor swapping circulating water at high back pressure, in the future.