Research On Stable Combustion Technology Of 300MW Subcritical Coal-Fired Boiler Under Super Low Load In Deep Cyclic Operation

In recent years,wind power,solar and other clean energy has developed rapidly with the installed capacity growing rapidly.The clean energy can provide clean power which reduce the environment pollution,but at the same time,there are many shortcomings,such as intermittence,undulatory property,randomness,weak supply capacity for short time and so on.So,it can't be completely consumed by China's power system,which poses a huge challenge to the security and stability of power system.Therefore,the NDRC and the National Energy Administration require flexibility reconstruction for the thermal power unit to release its potential in-depth peak adjustment capability in order to improve China's power system.However,many problems will occur when the unit is generating under deep cyclic operation.The main problem of boiler is the combustion instability due to the low coal quantity and temperature in the furnace.To solve this problem,this research will analyze how different parameter and reform method would affect the combustion in the furnace in super low load by numerical simulation and test.First,a 300 MW subcritical boiler in Dalian Ganjingzi Power Plant will be analyzed by numerical simulation.The result shows that reducing the primary air volume is important to flame ignition and stabilization which is most effective.But excessive reduction of primary air volume will have a very negative effect on the flow field inside the furnace.Raising the primary air temperature and reducing the fineness of pulverized coal particles can make the ignition point advance and have a certain effect of stabilizing combustion.The combustion adjustment test of the boiler will be carried out for stable combustion under the 30% low load which based on the above simulation results.However,the combustion adjustment technology cannot meet the requirements of lower load(20%).Therefore,a method for separating the primary air before the burner is proposed.The original burner will change to two small burner which have the same thermal load.The ignition heat of rich burner is lower than the original burner,so the combustion conditions will be improved.And then the hot smoke generated by rich burner would ignites the lean burner,which would promote the entire combustion process of the furnace to achieve the stable combustion.Through the numerical simulation and comparison,the feasibility of the rich/lean double nozzle burner was confirmed.The best separation ratio and the two-phase coal powder distribution method will be analyzed.Finally,the effect of reconstructing different burners will be analyzed.To summarize,this research puts forward the idea of low-load steady combustion technology under 30% and 20% load based on the 300 MW subcritical unit of Dalian Ganjingzi Power Plant,which provides reference for the same type units.