Synergies in co-pyrolysis of lignite and coal liquefaction residues

摘要

The results from TGA experiments at the temperature range of 200～900℃ evidentlydistinguished the different pyrolysis behaviors of lignite and coal liquefaction residues (DCLR);Meanwhile clear synergistic effects could be observed for the mixture. The investigation ofco-pyrolysis in a fixed-bed reactor found significant synergies in both pyrolysis product yields andgas product compositions. The tar yields for 80coals: 20DCLR blend determined experimentallyhigher than the calculated values were 0.826 wt. %, 0.594wt. %, 0.026 wt. % , when thetemperature increased by 100℃ from 400 to 600℃, meanwhile the gas yields determinedexperimentally higher than the calculated values were 0.118wt .%, 0.274 wt. %, and 1.058wt. %when the temperature increased by 100℃ from 600 to 800℃.The yields of CO and CO_2determined experimentally were obviously higher than the calculated values; the yields of H2determined experimentally were obviously lower than the calculated values under the range oftemperatures studied. The different synergies occurring at the temperatures 400-600 ℃ and600-800℃, and the possible mechanisms were described including the interaction between lignitevolatiles and DCLR particles. The enhanced devolatilisation of the blend was explained by thetransfer of hydrogen from DCLR to coal as well as the promotion of low-temperature thermaldecomposition of lignite by exothermic heat released from DCLR pyrolysis during itspolycondensation reaction stage, which made gas yields is relatively higher than the calculatedvalues.