Research And Operation Optimization Of Part-load Conditions Of 300MW CFB Unit During Heating Period

In recent years,according to the adjustment of national energy policy,combined heat and power(CHP)plants have gradually become one of the important development directions of thermal power generation units.The role of CHP plants is from a single transition to diversification.In addition to meet the increasing demand of urban and rural residents with the rapid development of the national economy,actively participating in electric power load and auxiliary power consumptiving new energy power have become the norm operation of CHP plants.Therefore,it is of great significance to study the heat supply mode and the energy consumption optimization for CHP plants.In this paper,a CHP plant in Xinjiang is selected as a case to research its low efficiency problems caused by(1)low live steam pressure determined by the current sliding pressure curve and(2)the heating steam parameters mismatching of supplied and demand during the heating period in winter.For this purpose,a simulation model based on design and operational data is established firstly,the accuracy of which in overall operating conditions is verified.On this basis,an optimized sliding pressure curve is proposed to improve the energy efficiency based on the analysis of overall heating conditions,proposal of conversion factor between electric and thermal output,the relationship between the mass flow of live steam and the opening ratio of main steam valve,and the statistics of practical operating data.A comparison is adopted to quantified evaluate the reduction of energy consumption before and after the proposed optimization.In addition,the retrofit from steam extraction heat supply to low-vacuum exhaust steam condensing heat supply is also analyzed based on thermodynamics,and the energy saving effect is quantified.After thermal performance analysis,some conclusions are drawn:a new unit sliding pressure curve of the heating period is established based on the analysis of power load conversion coefficient and unit operation data.In sliding pressure curve,after deducting water pump power consumption,the maximum increase of power generation power is 0.74MW and the maximum reduction of coal consumption of power generation is 0.6g/kWh through the simulation model calculating.The energy saving effect is obvious.By the condensing heating mode for the low-vacuum heating model,under the same heating load,the generating power of unit increase 22.32MW and the coal consumption of generating unit reduce 16.9g/kWh.In addition,with the reduce of the supply/return water temperature,the energy-saving effect is more obvious.The research results in this paper lay a scientific theory foundation for the determination and optimization of the sliding pressure curve and the heating mode transformation of the CHP during the heating period,which has practical guiding significance for the similar units to save energy and reduce consumption.