The Optimal Control Of Heat Efficiency On Combustion System Of CFBB

Energy and environment problem is one of the most pressing issues in China, which is related to sustainable development of country. Nowadays, Circulation Fluidized Bed Boiler (CFB Boiler or CFBB) is becoming the main coal combustion technique all over the world for its attractive advantages of high combustion efficiency and low gas emission. However, industrial CFB Boilers, especially medium and small types have low heat efficiency and they need more coal for burning. Compared to the big types, the medium and small boilers have more space for optimizing. In order to increase heat efficiency and low down coal consumption for these CFB Boilers, it is necessary to do some research on optimal control on boiler combustion system.Since research on optimal control system on heat efficiency of CFB Boiler has not been well-developed, the optimal control method on how to improve heat efficiency and low down coal consumption on combustion system of CFB Boiler were investigated in this paper, aiming at one industrial 135t/h CFB Boiler in Fujian. This research was based on the investigation in my laboratory before, including closed loop control on combustion system and the coal quality observation on CFB Boiler.Firstly, a new method for on-line calculation of heat efficiency on CFB Boiler was put forward in this paper, according to the GB10184-88. Based on some measurable operation parameters, including the pressure, temperature and the flow of mainstream, the water and the 1st and 2nd wind, which are collected online, input energy and utilization energy can be deduced respectively, and then the heat efficiency can be computed. Using spot data from a 135ton/h CFB Boiler unit in Fujian, the on-line calculation of heat efficiency was simulated and the result of industrial simulation indicates that this method was accurate and effective.Furthermore, the orthogonal experiment was preceded to analyze seven factors which contribute heat efficiency to CFB Boiler. Because it is hard to get the data of heat efficiency which are set on the orthogonal layout, the predictive model based on artificial neutral network was proposed. After comparing the generalization capability and the results of the real time simulation between the standard BP arithmetic and LM-BP arithmetic, the predictive model based on the LM-BP networks is established first. Then the orthogonal experiment was preceded and the result indicated that the ratio of wind and coal, the pressure of gas and the temperature of boiler were key factors. This result was validated by the industrial optimal experiment.After that, the optimal control of heat efficiency on combustion system of CFB Boiler was studied. Choosing heat efficiency, coal consumption, gas pressure, gas temperature, oxygen concentration and load of the boiler as input parameters and bed temperature, ratio of wind and coal as output parameters, the heat efficiency anti-model based on LM-BP arithmetic has been designed. Real-time industrial data for twenty-four hours were collected in this paper. Together with the industrial data, output data from the anti-model, other industrial parameters and the heat efficiency predictive model, the optimal data of heat efficiency and coal consumption could be obtained.Finally, the differences between industrial data and optimal data were compared and analyzed in this paper.The work in this paper provides a new way to help on-line optimal operation of the CFB Boiler through adjusting bed temperature of boiler and ratio of wind and coal. It is the fundamental research for establishing on-line optimal control system on CFB Boiler in future.