Online CO Monitoring During Low Temperature Oxidation of Zonguldak Coals

Abstract

ABSTRACT During low temperature oxidation of coals, due to half reaction of carbon with oxygen, concentration of CO is readily being increased and it is monitored by the field operators via gas detectors. In this study, low temperature oxidation tests were carried out for 26 samples, which were collected from Zonguldak hardcoal basin. In order to have observation CO concentrations levels during low temperature oxidation, a complete experimental set up was established. The experimental set up abovementioned includes two gas chromatographs (GC HP 5890 and GC HP 6890), one of which (HP 5890) is employed for oven purposes. As in the case of low temperature oxidation testing procedure, a starting temperature and the ramp is defined as 30°C and 0.5 °C/min, respectively. Every 15 minutes, (7.5°C increase) gas sample produced from coal via the process of low temperature oxidation was taken and analyzed by the gas chromatograph. Based on the results obtained, the amount of CO generated at low temperature (at 37.5 °C) was found to be a significant measure for the coal spontaneous combustion liability. As for the indicator gas for the spontaneous combustion of coal, results implied the fact that increase in the amount of CO generated during spontaneous combustion was observed. Due to the abovementioned fact in terms of indicator gas for spontaneous coal combustion, it was found out the fact that the increase in the amount is significant. CO (ppm) result at early temperature was found out to be in very strong relationship with corresponding spontaneous combustion liability test results. The correlation between CPT and CO (ppm) at 37.5°C for 26 coal samples was found out to have a correlation coefficient of 0.82, i.e. R2 = 0.8224. Increase in CO (ppm) was observed with the increase in the environment temperature for each of 26 coal samples studied. Based on the FCC index values (coal spontaneous combustion liability index) calculated for each of 26 coal samples, the correlation between CO (ppm) and the corresponding FCC index values yielded a correlation coefficient of 0.86, (R2 = 0.8585).