Abstract:Taking rape straw and anthracite and bituminous coal as the research object, based on the simultaneous thermogravimetric technology, the dynamic characteristics of cocombustion were studied systematically with different mass fractions of wheat straw (100%, 60%, 40%, 20%, 10% and 0) and the ratio was optimized. The results showed that WS was rich in volatile matter with a content of 75.69%, while bituminous coal had the highest fixed carbon content (54.77%). Therefore, the fuel ratio (fixed carbon/volatile) of BTC (167) was much larger than that of WS (014), indicating that bituminous coal was more conducive to combustion. There was significant difference on cocombustion characteristics under different mass fractions from TG and DTG curves. From DTG curves of cocombustion, it can be seen that as the proportion of wheat straw was decreased, the volatile combustion peak was gradually decreased from 2079%/min to 208%/min (WS10%). The maximum rate of fixed carbon combustion of wheat straw (4033%/min) appeared at 419℃. The ignition temperature was not significantly improved when the ratio of straw was declined to 10%, which was within 260~268℃, indicating a desirable performance of ignition. While the burn out temperature was significantly improved along with the decrease of straw from 520℃ (WS) to 596℃ (BTC). The comprehensive index (SN) value was decreased from 8.78×10-7%2/(K3·min2) to 1.17×10-7%2/(K3·min2) as the straw ratio was decreased, indicating that the combustion performance was gradually weakened. However, the group WS40% with a SN value of 3.60×10-7%2/(K3·min2) can ensure better combustion behavior. From DSC analysis, mixture with 40% propotion of WS can release heat up to 84.14% of BTC’s.In summary, based on the evaluation of combustion performance and improving heating value of mixture, the mass fraction of 40% was recommended for wheat straw when blended with bituminous coal for cocombustion.
