A Study of Co-Pyrolysis of Sewage Sludge and Rice Husk for Syngas Production Based on a Cyclic Catalytic Integrated Process System

Abstract

To promote higher-quality syngas production from biomass co-pyrolysis, this study prepared syngas through the secondary cracking of tar in cyclic catalytic pyrolysis steam based on a cyclic catalytic integrated pyrolysis (CCIP) system, the CCIP system process parameters were synergistically optimized based on the syngas yield and lower heating value (LHV) as indicators. The results showed that the mixing ratio and cycle rate was crucial to driving syngas generation, while the cycle rate was a key factor for tar reduction. The catalyst dosage mainly changed the syngas composition and promoted the generation of hydrogen-rich syngas. Optimization of the CCIP system reduced the liquid phase product yield by 6 wt.% and increased the gas product yield by 27 wt.% compared to the normal pyrolysis system based on sewage sludge (SS) pyrolysis, where the yields of H2, CH4, CO, and CO2 were increased by 131.51, 87.80, 223.57, and 210.45 vol%, respectively. The syngas LHV increased from 7.99 MJ/Nm3 to 11.31 MJ/Nm3 by 41.55 % through synergistic optimization. The co-pyrolysis of SS and rice husk and the development of pyrolysis tar reforming through pyrolysis steam circulation effectively improved the yield and LHV of syngas and achieved high-quality syngas recovery based on the CCIP system.

Keywords: Sewage sludge, Rice husk, Co-pyrolysis, Steam circulation, Tar catalytic reforming, High-quality syngas.