| Coal is the primary energy source in China, but coal combustion brings to serious environment pollution. To maintain the sustainable development of energy industry, circulating fluidized bed (CFB) combustion has already begun to be a popular technology of clean coal combustion in power plant boilers in China. With the development of supervision mechanism and implementation of stricter environment protection rules and laws, it can be imagined that the large-scale CFB boilers will be more widely used in coal fired power plants. At present, there are few large-scale CFB boiler units, which have already been put into use in China, so it is scare of experiences in design and operation. At the same time, people understanding of working process mechanisms in CFB is far from satisfied because of its complex nature. With the support of computer simulation technology, the real-time simulation models of full working scope which contain the main systems and auxiliary systems can be set up, it has an important significance to analyze the overall performances of CFB boiler and solve the problems existing in its design and operation. Based on the STAR-90 simulation system, the method of decomposing and integrating models of CFB boiler unit is studied, and the difficulties in modeling of the large and complex system can be well settled, by properly decomposing and integrating the systems. The engineering modular modeling method is firstly used in developing the real time dynamic simulation model of large scale CFB boiler unit, and the real-time engineering modular simulation model of the 450t/h CFB boiler unit which is the first of its kind made in China is successfully set up, including all its auxiliary systems. According to the mass and energy balance principles, the math models of the equipment and process in CFB boiler unit are founded, and its modular simulation algorithms are set up, mainly include combustor, cyclone separator, the firing gas duct, ash cooler, J-type loop seal valve, one-phase medium heat exchanger and so on. The modular modeling method is also introduced to fluid network model development of CFB boiler unit. The system model integration methods of all kinds of fluid networks, such as one-phase, steam-water and gas-solid two-phase fluid networks etc., are discussed. By combining matrix solving the math models of fluid network with modular modeling method, the model precision and the efficiency of modeling are greatly improved. On the basis of actual operation data of the 450 t/h CFB boiler unit, the dynamic characteristics of the process parameters of the unit such as gas-solid pressure, bed temperature etc., is systematically studied. It provides a basis for verifying and improving the fidelity of the simulation model. With the test results of the real-time simulation model of CFB boiler, the dynamic and static characteristics of the CFB power unit is studied, simulation results show that the models can correctly simulate the operation performance of CFB boiler unit, and it is good for understanding and mastering the skills in operation and regulation of the large-scale CFB power unit. With the support of STAR-90 simulation system, the author develops the first real-time simulation model of the 450t/h CFB boiler unit, which is successfully put into use in the first 125MW CFB power unit simulator and 200MW header style CFB power unit simulator in China. It concludes that the engineering modular modeling method is suitable for complex system modeling and model debugging, and it is convenient for accumulating and reusing the model knowledge as well.
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