• Energy Research

Abstract Not only can the incineration provide an effective waste stream reduction, but also it enhances the energy recovery. However, the combustion performance of textile dyeing sludge is poor due to its low combustible content and low calorific value. This study proposes to compensate for the defects by its co-combustion with cattle manure. The co-combustion exerted an inhibitive effect between 350 and 500 °C and a positive effect between 600 and 1100 °C on the thermal degradation. The strongest enhancement occurred with the blend ratio of 1:1. The co-combustion reduced the maximum SO2 emission and produced fewer gas species including CO2, CO, H2O, ketones, aldehydes, and low molecular weight chain-alkanes. The experimental and simulation results about mineral transformations showed that the blend ash consisted of SiO2, Fe2O3, CaMgSi2O6, NaAlSiO4, NaAlSi3O8, and Na2SO4. The blend ash had the lowest fusion temperature due to the formation of a low temperature eutectic. The findings provide insights into controls over gas emissions, energy recovery, and ash reutilization, essential to the development of cleaner and sustainable co-combustion systems.

Abstract The study bases on the pyrolysis characteristic, kinetic, and thermodynamic parameters and evolved gas analysis to quantity Chinese medicine residues (CMR) and uses artificial neural network (ANN) to reconstruct and jointly optimize pyrolysis. The main weightlessness interval of CMR is between 150 and 600 °C including organic matter decomposition. Four model-free methods and one model-fitting method were provided to find function mechanisms and kinetic parameters show it existing kinetic compensation through pyrolysis. TG-FTIR finds the gases and functional groups included CO2, C O, H2O, CH4, CO, C C, and C–O. And the main pyrolytic products were detected included esters, phenols and acids et al. 9-octadecenoic acid (z)-, methyl ester as one of the high quality products was in the highest proportion about 53.75%. The temperature-, heating rate-, and their non-linear dynamics of the multiple pyrolysis response surfaces were reconstructed and jointly optimized using an artificial neural network algorithm. Finally, the study is helpful for Chinese medicine residues high-value utilization.

Abstract The pyrolytic behaviors, kinetics, decomposition mechanisms and product distributions and joint optimization of Lentinus edodes stipe (LES) were quantified. Its main pyrolysis stages (the decomposition of hemicellulose) occurred between 200 and 400 °C. Random nucleation and nuclei growth (A0.91), and orders of reaction (F1.6 and F2.1) best explained the three sub-stages of the LES pyrolysis mechanism, respectively. The gas emissions were in good agreement with pyrolysis behavior. The main distributions of the pyrolytic products were classified into the 12 types of acids, alcohols, aldehydes, ketones, esters, phenols, glucopyranoside, aliphatic hydrocarbons, furans, aromatic hydrocarbons, N-heterocyclic substances, and N-containing substances. Cellobiose was found as pyrolytic product during 400 and 600 °C. For economic and practical reasons, the target functions of the four responses for the LES pyrolysis were jointly best optimized combining the temperature of 550 °C and the heating rate of 12.5 °C/min. This study offers theoretical and practical insights into the pyrolysis performance and products of LES or similar second-generation feedstocks in a thermal reactor.

Not only does pyrolysis recover energy and value-added by-products but also reduces waste stream volume. The low volatiles and high ash contents of textile dyeing sludge (TDS) limit its mono-pyrolysis performance. This study aimed to conduct an in-depth analysis of its co-pyrolytic performance with cattle manure (CM). The co-pyrolysis enhanced the volatiles emission from the early devolatilization stage whose reaction mechanism shifted from a diffusion model to a reaction-order model. The further cracking of macromolecular materials was mainly elucidated by the reaction-order model. The temperature dependency of the co-pyrolytic gases was of the following order: aliphatic hydrocarbons > CO2 > alcohols, phenols, ethers, aldehydes, ketones, and carboxylic acids. The main co-pyrolytic volatile products were coumaran and 4-vinylguaiacol. The relative content of guaiacol-type components could be enhanced by co-pyrolysis and lowering the operational temperature to 450 °C. The interaction of co-pyrolysis enriched the char aromaticity. Our findings provide practical insights into the control and application opportunities and limitations on the high value-added energy and products from the co-pyrolysis of TDS and CM.

Abstract The co-pyrolysis technology of the second-generation feedstocks has both engineering and environmental advantages towards resource recovery, waste stream reduction, and energy generation. However, there exists a large knowledge gap about the co-pyrolytic mechanisms, kinetics, emissions and products of biomass wastes. This study aimed to quantify the co-pyrolytic interactions between the five (N2, CO2, and three mixed) atmospheres and the two feedstocks of sewage sludge (SS) and coffee grounds (CG) as well as their emissions and products. Thermogravimetric-Fourier transform infrared spectrometry, two-dimensional correlation spectroscopy and pyrolysis-gas chromatography/mass spectrometry analyses were combined. An eight-parallel distributed activation energy model was adopted to elucidate the dynamic reaction mechanisms in the co-pyrolytic atmospheres. The co-pyrolytic interaction changed the maximum weight loss rate of the first peak by −2.5 to 38.6% and −1.9 to 36.9% in the N2 and CO2 atmospheres, respectively. The mass loss rate peak in the first stage was higher in the N2 than CO2 and mixed atmospheres, while the peak temperature of the maximum mass loss rate in the second stage declined with the elevated CO2 concentration. The replacement of N2 with the different CO2 concentrations significantly increased the activation energies of the 5th and 7th pseudo-components. The temperature dependency of evolved gases was of the following order: ethers/esters → acids/ketones/aldehydes/CO2 → hydrocarbons in the N2 atmosphere, and acids/ketones/aldehydes → esters/ethers → hydrocarbons in the CO2 atmosphere. The co-pyrolysis improved the yields of the hydrocarbon and phenol-type compounds and reduced the formations of the acid and nitrogenous compounds. Our results yielded valuable insights into a cleaner co-pyrolysis process.

Abstract This study aims at characterizing pyrolysis/gasification behaviors and products of spent mushroom substrate (SMS) in the CO2 and N2 atmospheres. The major decomposition stages occurred between 200 and 600 °C with the mass losses of 60.4 and 61.5% at 20 °C/min in the CO2 and N2 atmospheres, respectively. The maximum mass loss rate grew with the increased heating rate, while DTG curves shifted toward a higher temperature. Volatiles were released easier in the N2 than CO2 atmosphere with a higher comprehensive devolatilization index and decomposition rate. At above 750 °C, the char gasification in the CO2 atmosphere resulted in a significant mass loss as well as a less char yield. Average activation energies by the Flynn-Wall-Ozawa method were estimated at 212 and 214 kJ/mol in the CO2 and N2 atmospheres, respectively. The higher thermodynamic parameters in the N2 than CO2 atmosphere indicated the higher reactivity of the pyrolysis in the N2 atmosphere. The reaction mechanisms of the volatiles decomposition were best described by g(α) = (1-α)−1-1 (R2 model) in the range of 200–370 °C in both atmospheres. The major pyrolysis products at 800 °C were identified using Py-GC/MS and composed mostly of aromatic compounds such as toluene and x-methyl-naphthalenes.

Abstract The increased amounts of manure have become an issue of environmental management due to the rapid growth of livestock industry. This study quantified the pyrolytic performance and gaseous products of cattle manure using (derivative) thermogravimetric ((D)TG), Fourier transform infrared spectrometry (FTIR) and pyrolysis–gas chromatography and mass spectrometry (Py-GC/MS) analyses. The pyrolysis process of cattle manure was determined to occur in three stages, with the main reaction in the range of 161–600 °C. The N2 atmosphere was found to be more favorable for the release of volatiles according to a higher comprehensive pyrolysis index in the range of 30−600 °C. The lower activation energies were shown to be required in the CO2 than N2 atmosphere. Random forests algorithm outperformed multiple linear regression, gradient boosting machine, and artificial neural networks for the prediction of mass loss due to the cattle manure pyrolysis. The main gaseous products were CO2, phenol (23.23%), and furans (12.98%). The theoretical and practical guidance for the energy and resource utilization of cattle manure was provided by this study.