HRL was engaged by a client to perform a mill testing campaign at their power station. Limited milling performance test data was available, making it difficult to correlate mill performance with wear rates and combustion performance. A comprehensive testing program was prepared by HRL to investigate the correlation between mill performance and maintenance requirements on mills.
Providing Critical Insight on Milling Performance Case Study
Challenge
Solution
HRL undertook the following mill performance testing:
Clean air testing: The clean air testing involved measuring primary air flow rates and distributions in the mill outlet pipes using specialised probes and instrumentation.
Dirty Air Testing: The dirty air testing included isokinetic sampling of PF for different mill conditions and classifier settings. Pulverised fuel (PF) sampling was performed using a Rotaprobe device and the collected samples were analysed for particle size distribution.
Results
The primary air distributions were found to be generally even for each mill at both power stations. The PF distributions, however, showed significant variability between mills and PF pipes for both coal flowrates. The variability in PF distribution was greater than the variability in primary air flowrate/velocity distribution. The results also indicated differences in fineness and coarseness between mills and between different conditions. HRL also identified significant differences between the measured parameters and DCS values.
Overall, the testing program provided valuable insights into mill performance. The methodology used allowed for the evaluation of primary air and PF distributions, particle size distribution, and the comparison of measured values with DCS values. The results highlighted the need for more regular mill testing to better understand mill performance over the mill lifetime. The testing program demonstrated HRL's expertise and capabilities in power and combustion performance engineering.
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