Effect of bed depth on characterisation of slow pyrolysis products

The trend towards separation of waste for material recovery could assist with the implementation of waste pyrolysis and gasification processes. Following the previous work on slow pyrolysis of segregated waste materials, this study investigated the effect of bed depth on the yields and properties of pyrolysis products in a fixed bed pyrolyser. The results showed that the bed depth had a strong influence on the properties of pyrolysis products but a small effect on the yield of products. Differences in the liquid yield between the two cases of bed depth (17–57 vol% of the reactor) were observed at temperatures above 500 °C while the difference in the char yield was negligible. The aqueous fraction was 5–15% higher for the bed depth of 57 vol% than for the bed depth of 17 vol%. Increase in the bed depth increased the H/C ratio by a factor of 2–6 in the char product and the CO/CO2 ratio by a factor of 1.74 in the gas product but slightly decreased in the H/C ratio in the liquid product.