Application of the Mahalanobis distance on evaluating the overall performance of moving-grate incineration of municipal solid waste.

In this study, there were 54 municipal solid waste (MSW) moving-grate incineration power plants investigated in China. The flue gas emission data of CO, NOx, SO2, HCl, and particles were collected as monthly means directly from the plants for 12 consecutive months from 2011 to 2012, as well as the annual cumulative consumption data of activated carbon, CaO/Ca(OH)2, and #0 diesel. Eventually, 37 out of the 54 plants were evaluated on the overall performance using the Mahalanobis distance. As a result, there were 31 total outliers (potential errors or risks in the operation) detected from the flue gas emission data in 9 out of 37 plants. The results revealed that the Mahalanobis distance was an effective method to evaluate the overall performance of MSW moving-gate incineration from the massive normal-looking flue gas emission data. It was also illustrated that reducing the frequency of the load changes was more important than reducing the magnitude of the load changes, especially in the range between - 10 and 10% of the load changes. Furthermore, the average consumption of activated carbon, CaO/Ca(OH)2, and #0 diesel in the MSW moving-grate incineration power plants was 0.32 ± 0.13 kg, 7.75 ± 3.06 kg, and 0.15 ± 0.12 kg per ton of MSW, respectively.