The huge amount of food waste (FW), containing high organic matter content and moisture, is difficult to be well treated. Supercritical water gasification (SCWG) can efficiently convert FW to H-rich syngas. However, it requires high energy input due to the high temperature and high pressure. This study provided an innovative "two-steps heating process" for the SCWG of FW, which firstly utilized hydrothermal (HT) pretreatment to shorter time of SCWG. The effects of different HT temperature (200 °C, 250 °C, 300 °C, 30 min) to SCWG temperature (480 °C, 30 min) and the different residence time (20 min HT - 40 min SCWG, 30 min HT - 30 min SCWG, and 40 min HT - 20 min SCWG) on total syngas yield, carbon conversion efficiency (CE), cold gas efficiency (CGE), and hydrogen conversion efficiency (HE) were studied. Moreover, the energy input by means of electricity consumption in each experiment was measured to determine the energy saving rate. The optimal condition (200 °C, 20 min HT - 40 min SCWG), obtaining the gas yield (17.22 mol/kg), CE (20.10%), CGE (22.13%), and HE (41.54%), was higher than the gas yield (16.53 mol/kg), CE (19.98%), CGE (20%), and HE (38.08%) of directly SCWG (60 min, 0 °C-480 °C). Moreover, the TOC of derived liquid and the pyrolysis characteristics of solid residues were analyzed. Additionally, it was also observed the HT pretreatment helped to reduce the electricity consumption. The highest energy saving rate was 15.58%.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142331 | DOI Listing |
FEBS Lett
October 2024
Institute for Molecular Medicine Finland (FIMM), HiLIFE, University of Helsinki, Finland.
Bioresour Technol
October 2024
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, No.28, Xianning West Road, Xi'an 710049, China.
This article reveals the basic laws of straw supercritical water gasification (SCWG) and provides basic experimental data for the effective utilization of straw. The paper studied the impact of three operational conditions on the production of high-calorific value hydrogen-rich combustible gases through SCWG of straw within a quartz tube reactor. The findings reveal that elevated reaction temperatures, extended residence times, and reduced feedstock concentrations favor the SCWG of straw.
View Article and Find Full Text PDFMaterials (Basel)
June 2024
State Key Laboratory of Multiphase Flow in Power Engineering (SKLMF), Xi'an Jiaotong University, No. 28 Xianning West Road, Xi'an 710049, China.
Supercritical water gasification (SCWG) technology is highly promising for its ability to cleanly and efficiently convert biomass to hydrogen. This paper developed a model for the gasification of rice straw in supercritical water (SCW) to predict the direction and limit of the reaction based on the Gibbs free energy minimization principle. The equilibrium distribution of rice straw gasification products was analyzed under a wide range of parameters including temperatures of 400-1200 °C, pressures of 20-50 MPa, and rice straw concentrations of 5-40 wt%.
View Article and Find Full Text PDFMolecules
May 2024
Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada.
Supercritical water gasification (SCWG) of lignocellulosic biomass is a promising pathway for the production of hydrogen. However, SCWG is a complex thermochemical process, the modeling of which is challenging via conventional methodologies. Therefore, eight machine learning models (linear regression (LR), Gaussian process regression (GPR), artificial neural network (ANN), support vector machine (SVM), decision tree (DT), random forest (RF), extreme gradient boosting (XGB), and categorical boosting regressor (CatBoost)) with particle swarm optimization (PSO) and a genetic algorithm (GA) optimizer were developed and evaluated for prediction of H, CO, CO, and CH gas yields from SCWG of lignocellulosic biomass.
View Article and Find Full Text PDFEnviron Pollut
February 2024
Chemical Engineering Department, University of Málaga, Campus de Teatinos s/n, 29010, Málaga, Spain.
In this study, the production of activated carbon (AC) through the chemical activation of waste tire (WT) using HPO and KOH for H production by SCWG of oily sludge (OS) donated by Persian Gulf Star Oil Company was investigated. HPO was the best activating agent based on some pretests results, and then the synthesis of AC was optimized using Response Surface Methodology. Based on BET surface area of synthesized ACs, thirty combinations of the four variables namely; activation temperature (350-550 °C); activation time (1-4 h); HPO to WT ratio (1-3 w.
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