Experimental study on co-pyrolysis characteristics of oily sludge and waste textiles targeted at the fuel substitution for cement kilns

Abstract

Combining utilization of pyrolysis products with fuel substitution in cement production is an innovative approach. While single pyrolysis of oily sludge or waste textiles has been studied, their co-pyrolysis behavior remains unclear. To explore the potential of cement kiln tail gas as the co-pyrolysis medium and assess pyrolysis products as cement alternative fuels, laboratory-scale co-pyrolysis experiments of cold-rolled oily sludge (CROS) and waste textiles (WT) were conducted. Effects of CROS/WT mass ratio, temperature, and atmosphere on product yields and characteristics were investigated. More CROS in the mixture increased oil yield and saturates content in the oil. More WT increased gas and residue yields, aromatics and resins in the oil, and CO content in the gas. A positive synergistic effect occurred only at low levels of WT addition. Under simulated cement kiln-tail gas, a small amount of O₂ raised resin content in the oil and reduced CH₄ and H₂ in the gas. The optimal co-pyrolysis performance was achieved at CROS/WT mass ratio of 8:2, 550 °C, and N₂/CO₂ atmosphere. The oil and gas yields reached 49.62% and 19.01%; saturates and aromatics contents in the oil were 42.67% and 31.17%; the sum of H₂ and CH₄ contents was 47.74%.