The selection of an injection coal depends largely on its cost, its physical and chemical properties, and on the intended application. For low injection levels, virtually any type of coal can be used, and its performance can be predicted with relative ease from a small subset of simple coal quality parameters. However, as injection rates increase, more complex characteristics such as combustibility, char reactivity and flow characteristics influence the selection and use of a coal or coal blend. In general, low-volatile, higher rank bituminous coals offer higher coke replacement ratios, but can be more difficult to convey and burn. Conversely, high-volatile, lower rank coals are generally more reactive and easier to convey, but carry lower coke replacement ratios and may in some instances contribute to furnace instability. Experience with various types of injection coal and existing and emerging standards for selecting injection coals are reviewed and discussed.
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