Large Thermal Power Generating Set Low And Medium Load Operation And Energy Saving Optimization

Along with the variations of the relationship of China's electric power market supply and demand,of the load curves of power grid varied in real time,and the difference of the peak and valley load increased too,and the proportions of clean energy such as nuclear power,wind power and solar energy keep rising.This leads the low-load operation time of coal-fired power units grow continuously,and requires large thermal power unit to be equipped with wide range of load frequency control capability.In addition,with the adjustment of the national economic structure and the impact of environmental protection policies,the number of utilization hours of most of the coal-fired power generating units have been greatly reduced,and thus induced the widespread long period situation of medium-low-load conditions operation.For a safety,environmental protection and economic units operation in medium-low-load conditions,it is urgent to carry out the research and practice of medium-low-load operation and energy conservation optimization for large thermal power generating units.This work aimed at the control optimization of the equipping sliding pressure variable flow,and the varied flow control of the condensate for large steam turbine units,and analyzes the medium-low-load conditions operation and the energy saving engineering practice on a 600 MW supercritical 660 MW ultra-supercritical unit.Comparing with the high load operation condition,the energy consumption of the unit is increased greatly with the low-load mode and the economic indicators are decreased obviously.By the medium-low-load operation,there are large throttle losses in the original steam turbine distribution,which requires optimization of the steam distribution and the slip pressure.Besides,deep optimizations of frequency conversion are needed in auxiliary engines with high power consumption,such as condensate pumps.With the previous research and analysis,a medium-low-load operation and energy saving optimization for a No.1 unit in a 600 MW supercritical power plant has been implemented since 2015 with satisfying energy saving effect.In 2016 and 2017,this medium-low-load optimization results was applied to the No.3 and No.4 units of 660 MW supercritical coal-fired plants.In this paper,the necessity,feasibility,implementation and effects of the frequency conversion optimization of steam turbines with steam pressure and condensate system are described in this paper.The method of combining investigation and experiment is mainly used.Using the new functional logic module,it can switch and drop each other,and it is difficult to gradually promote the application of the technical route.Find out the potential energy saving point by the energy saving diagnosis analysis of the unit and then to apply it to another unit after the previous successful implementation.This project can achieve the goal of energy saving and the consumption reducing with the original equipment and facilities unchanged,only by through the test,the logical optimization and altering operation modes.It is expected to have a great yield with small investment with universal adaptability,and the research results are easy to be applied,which provides reference and basis for the energy saving and consumption reducing of similar units.