Research On Peak Shifting Performance Optimization Technology Of Large CFB Unit

Because of its low-pollution, coal adaptability, the relative low cost, and ability to transfer load, the Circulating Fluidized Bed Boiler (CFBB) has got more and more widely used. Compared with Pulverized Coal Boiler, the CFBB has some characteristics such as a small affact by coal coal, good load regulation characteristics, a strong low-load stable-combustion capability, be hard to stall, be suitable to participate in power grid peak shaving. The research of the variable load capacity, is helpful to further adapt to the load of power grid.Based on the 8th of 300 mw circulating fluidized bed boiler in yunnan as the research object, the paper takes research and optimization On the variable load capacity.First of all, set up the CFB boiler dynamic characteristics mathematical model. Dynamic characteristics of mathematical model of CFB boiler is mainly composed of fluid flow model, the heat transfer model in the chamber of a stove, and and the dynamic equilibrium equations. Fluid flow model is established By using the model of a gas-solid flow. The furnace is divided into upper dilute phase zone and lower dense-phase zone, considering the radiation and convection heat transfer in the hearth, furnace heat transfer model is established By using the model of a small room, the underpants type furnace is divided into four small rooms, then establish dynamic balance equation of furnace.Secondly, establish CFB boiler dynamic characteristics simulation model of by using APROS simulation support system. The boiler can be divided into five systems:specific system, soda system, combustion chamber of a stove, material circulation system and the control system, connectting each department which is similar to the form of a hyperlink by reusing cable modules of APROS in simulation support system. And then form the overall simulation model of the boiler.Thirdly, validate 300 mw circulating fluidized bed boiler dynamic characteristics simulation model. Compare working condition of boiler design data and the field test data to working condition of boiler design simulation test, primary air volume step response simulation test, and coal amount step response simulation experiment data.Finally, do quick lifting load simulation test in the different load range of CFB boiler dynamic characteristics simulation model, And analyze the test process and results. The conclusion is the fastest rate is 7.0 MW/min when elevating load, and 5.4 MW/min when reducing load. It is faster than the rate of increasing or decreasing the load of 3.0 MW/min provided by the boiler instructions significantly. And putting forward to optimization strategy of CFB boiler variable load capacity.