| Pulverized coal boiler is the most important equipment in China to produce the steamneeded for electricity production, but in recent years, because of the shortage of highquality coal, the operators have no choice but use non-design coal, which is usually lowquality and high moisture content coal, this lead to a decrease of the boiler efficiencycaused by low combustion efficiency.In this thesis, an analysis is performed on a power plant in China which chooses to usenone-design coal because of the short supply of high quality coal, some suggestions aregiven based on the problems it is confronted with, which are:1. A new type mill, MPS-HP-Ⅱ is recommend, because the coal powder fineness from the old mill can’t meet therequirement;2. Because of the frequent fluctuations of the supplied coal quality, theoperators can not set the operating oxygen content at a proper value in time, so a calculationmethod to determine the operating oxygen content is recommended.In order to implement the two suggestions, two researches are carried on. Firstly, amax output calculation model for the MPS-HP-Ⅱmill is put up and tested, which will act asa basis for the selection of the mill; Secondly, a new calculation model for optimizedoperating oxygen content is given based on researches existed, which is proven with somedefects in the experiments later, then a modification model which contains a convertedwater factor is given and tested to be accurate.At the same time, a detailed description of the experiment steps is given, as so as thedata processed method which also contains the error analysis methods and a description ofthe instruments used. To make it easier for the operators to use the new type of mill, in thethesis there is a research on the operation characteristics of the mill, mainly how theprimary air rate, grinding forces, coal feeding rate and the dynamistic classifier affect themill. Some suggestions are given for using the optimized oxygen content calculation model. |
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