Installation of the XO inline particle sizer to monitor milling production can ensure that over-milling and under-milling are easily and quickly be detected with real-time measurements, and the process can be adjusted accordingly.
If the coal is excessively coarse due to under milling, then there will be higher levels of un-burnt carbon in the ash. This will adversely affect the efficiency of the process and create a less saleable by-product.
Conversely coal feed which is milled too fine produces areas of high temperature which lead to higher levels of NOx emissions and flame instability. This results in loss of efficiency incurred by unnecessarily over grinding of the fuel. An optimum particle size distribution between these two extremes is highly desirable to ensure that power generation costs and emissions are kept to a minimum.
Xoptix technical director Richard Graves explained the importance of accurate milling to control NOx emissions. “Our XO particle sizer helps coal mills to ensure optimization of milling, which helps save production costs, but also reduces NOx emissions too,” he said. “We place great importance on producing green technology that helps the environment and this ethos will always remain firmly rooted at the heart of the Xoptix culture.”
Generally coal should be pulverised until 92% is smaller than 74 microns and ideally there should be less than 2% greater than 300 microns.