Research On Optimal Operation For Energy-saving Of Large-scale Circulating Fluidized Bed Unit

Circulating fluidized bed (CFB) combustion technology is a new technology of power plant conforming to the national environmental protection policy,industrial policy and market demand. Because energy crisis, energy conservation and problem of environment protection is more and more prominent, CFB unit got rapid development in our country, especially large-scale CFB unit. At present, our country has successively constructed a batch of300MW CFB units.Large-scale CFB unit has many advantages, but because of its complexity and particularity, at present it has the prevalent problems of higher energy consumption level. Through many times investigation, the reason why CFB unit has high energy consumption is that some control systems of CFB boiler cannot run automaticly. It not only strengthens the labor intensity of operating-worker, but also can’t guarantee the optimization operation of the unit. Therefore, it is one of the important problems to be solved immediately to study the control characteristics of large-scale CFB and improve the control effect. The paper studys the optimal operation of large-scale CFB unit from the control point, in order to achieve the purpose of saving energy by optimizing the operation. The following is the main work in the paper:(1) Energy-loss analysis was done according to large scale circulating fluidized bed unit.Firstly analyze the method of boiler performance computing and geive an example with field data.And then study the way to determine target value of operation. At last, based on loss-analysis theory establish a model of loss-analysis of large-scale circulating fluidized bed unit.(2) Analysis control problems of circulating fluidized bed unit and study the optimal control strategy of main steam temperature,bed temperature and coordinated control. Study twice optimal control(TOC) theory and find its problems. A control scheme of bed temperature is designed based on improved TOC which can get good control effect. Based on adaptive control and fuzzy control, Smith predictive control is improved, and then the optimization control scheme of main steam temperature was presented based on the improved Smith predictor. The simulation shows good control effect can be got.Analyse the reason why coordinated control of CFB cannot run automaticly.According to problems of big delay and instable coal qulity.optimal control strategy of coordinated control was presented and was tested in filed.(3) In order to realize online energy-loss analysis and optimal control strategy,design and develop a optimal operation system of large scale circulating fluidized bed unit.Real-time database is the key technology of development of optimal operation system.Develop a real-time database fistly using I/O completion port and red-black tree algorithm which has been applied in many projects. Object of energy-saving could be got after it was applied to a power plant.