The effect of cyclic catalytic pyrolysis system on the co-pyrolysis products of sewage sludge and chicken manure, focusing on the yield and quality of syngas

This study presents an innovative Circulating Catalytic Pyrolysis System (CCPS) designed for the co-pyrolysis of sewage sludge(SS) and chicken manure(CM), aimed at addressing the challenges of low syngas yield, low calorific value, and high tar production in traditional biomass pyrolysis. By integrating steam cycling and tar catalytic reforming, the CCPS significantly enhances both the yield and quality of syngas. Systematic optimization of process parameters such as feedstock mixing ratio, cycling speed, and catalyst dosage reveals that the optimal mix ratio of sludge to CM is 25:75 w/w, with an optimal cycling speed of 1050 r/min and a catalyst dosage of 2.5g. Under these conditions, the synergistic effects of co-pyrolysis are most pronounced, and due to increased residence time, the pyrolysis steam can more fully circulate and crack, significantly increasing the yield and low heating value (LHV) of syngas while reducing tar production. Compared to the solo pyrolysis of sludge, the syngas yield increased by 26.49 %, tar yield decreased by 4.13 %, and the heating value of syngas increased by 38.75 %, demonstrating CCPS's ability to recover energy and enhance syngas quality. This study investigates the pyrolysis characteristics and three-phase products under various parameters. By integrating economic efficiency and energy performance analyses, it validates the stability and advantages of cyclic catalytic pyrolysis, providing robust theoretical and technical support for its practical application and promotion.