Energy Systems Engineering / Enerji Sistemleri Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4752

Browse

Filters

2020 - 20224

Settings

Institution Author: search.filters.institutionAuthor.Yıldız, GürayWoS Q: search.filters.wosQuartile.Q1

Search Results

Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 13
    Citation - Scopus: 14
    Perspectives of Biomass Catalytic Fast Pyrolysis for Co-Refining: Review and Correlation of Literature Data From Continuously Operated Setups
    (American Chemical Society, 2022) Prins, Wolter; Yıldız, Güray
    For the co-processing of pyrolysis-based biocrudes within petroleum refineries, a degree of conditioning/upgrading involving the cracking of the oligomers and (partial) removal of oxygen could be operationally beneficial. By inducing a complex set of reactions in biomass-derived fast pyrolysis vapors, catalytic fast pyrolysis (CFP) ensures significant changes in oxygen functionalities and alleviates oxygen concentration in the resulting liquid intermediate (CFP-oil). Due to its reduced oxygen content and acidity, CFP-oil could be considered suitable for co-feeding in FCC units and/or for co-hydrotreatment (co-HT) with gas oils within the existing crude oil processing infrastructure. On the operational side, however, research concerning CFP of biomass has shown poor results: deoxygenation of pyrolysis vapors goes along with a progressive reduction in CFP-oil yield. Apart from any control over catalyst activity, selectivity, and lifetime, the other critical issue is in the process design, which is complicated by rapid catalyst deactivation through coke formation and catalyst poisoning by biomass-originated minerals. This review analyzes the outcome of research efforts concerning in- and ex situ CFP of biomass based on carefully selected literature studies reporting the results obtained from meso- and macrolevel laboratory-scale setups, pilot, process development units (PDU), and (semi-) commercial process units, wherein the biomass feedstock and catalyst is fed continuously. Key operational aspects such as the reactor technology, reactive medium, processing mode, and optimization of process parameters are addressed. The performances of continuously operated CFP units were benchmarked through a comparison of yields and elemental compositions of (by-)products. Despite the considerable research efforts related to CFP technology development, the co-processing of CFP-oil is still in its infancy. However, in close collaboration with refinery professionals, it could be made a serious candidate for biobased co-feeding. For refinery integration, quality parameters of CFP-oil, e.g., acidity, stability, and miscibility, should be considered as crucial as its oxygen content.
  • Article
    Citation - WoS: 39
    Citation - Scopus: 42
    Prediction of Char Production From Slow Pyrolysis of Lignocellulosic Biomass Using Multiple Nonlinear Regression and Artificial Neural Network
    (Elsevier, 2021) Li, Ting Yan; Xiang, Huan; Yang, Yang; Wang, Jiawei; Yıldız, Güray
    Char produced from lignocellulosic biomass via slow pyrolysis have become one of the most feasible alternatives that can partially replace the utilisation of fossil fuels for energy production. In this study, the relationship between compositions of lignocellulosic biomass, operating conditions of slow pyrolysis, and characteristics of produced char have been analysed by using multiple nonlinear regression (MnLR) and artificial neural networks (ANN). Six input variables (temperature, solid residence time, production capacity, particle size, and fixed carbon and ash content) and five responses (char yield, and fixed carbon, volatile matter, ash content, HHV of produced char) were selected. A total of 57 literature references with 393-422 datasets were used to determine the correlation and coefficient of determination (R-2) between the input variables and responses. High correlation results (>0.5) existed between pyrolysis temperature and char yield (-0.502) and volatile matter of produced char (-0.619), ash content of feedstock and fixed carbon (-0.685), ash content (0.871) and HHV (-0.571) of produced char. Whilst the quadratic model was selected for the regression model, then the model was further optimised by eliminating any terms with p-values greater than 0.05. The optimised MnLR model results showed a reasonable prediction ability of char yield (R-2 = 0.5579), fixed carbon (R-2 = 0.7763), volatile matter (R-2 = 0.5709), ash (R-2 = 0.8613), and HHV (R-2 = 0.5728). ANN model optimisation was carried out as the results showed trainbr training algorithm, 10 neurons in the hidden layer, and tansig and purelin transfer function in hidden and output layers, respectively. The optimised ANN models had higher accuracy than MnLR models with the R-2 greater than 0.75, including 0.785 for char yield, 0.855 for fixed carbon, 0.752 for volatile matter, 0.951 for ash and 0.784 for HHV, respectively. The trained models can be used to predict and optimise the char production from slow pyrolysis of biomass without expensive experiments.
  • Article
    Citation - WoS: 33
    Citation - Scopus: 39
    Bibliometric Analysis of Research Trends on the Thermochemical Conversion of Plastics During 1990-2020
    (Elsevier, 2021) Khatun, Roomana; Xiang, Huan; Yang, Yang; Wang, Jiawei; Yıldız, Güray
    The aim of this bibliometric analysis was to evaluate the trends in literature and the impact of publications that have been published during the period 1990-2020, in the field of thermochemical conversion of plastics, namely gasification, liquefaction and pyrolysis. SCOPUS was used and data was vetted via MS Excel, with analysis being completed via MS Excel and VOSViewer. A total of 1705 publications were used in the study, and China was identified as the most productive country. Pyrolysis was the most researched technology with over 88% of publications, while liquefaction accounted for less than 3% of the total publications. Across all three technologies, polyethylene (PE) was the most commonly occurring type of plastic. Journal of Analytical and Applied Pyrolysis had the highest number of publications and total citations. However, Energy Conversion and Management had a higher impact factor and higher average citations per publication. University of Alicante was identified as the most productive university with a total of 45 publications, while University of Leeds was the most commonly cited with an average of 65 citations per publication. The keyword analysis showed that copyrolysis with biomass and catalytic pyrolysis are gaining increased interests.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 19
    Ex Situ Catalytic Fast Pyrolysis of Lignin-Rich Digested Stillage Over Na/Zsm-5, H/Zsm-5, and Fe/Zsm-5
    (American Chemical Society, 2020) Priharto, Neil; Ghysels, Stef; Opsomer, Wim; Ronsse, Frederik; Prins, Wolter; Pala, Mehmet; Yıldız, Güray
    The global increase in lignocellulosic ethanol production goes in tandem with an increase in lignin-rich stillage that remains underutilized to date. Anaerobic digestion could valorize residual (biodegradable) organic fractions into biogas, leaving a lignin-rich digested stillage (LRDS). This LRDS from the lignocellulosic ethanol production has been assessed as a feedstock for slow and fast pyrolysis in earlier studies, with the intention to increase the overall output of useful products or energy carriers from the starting material. While using this lignin-rich feedstock, ex situ catalytic vapor-phase upgrading (VPU) of fast pyrolysis vapors with fractional condensation was conducted over Na/ZSM-5, H/ZSM-5, and Fe/ZSM-5 catalysts. Semicontinuous fast pyrolysis experiments have been carried out at a reaction temperature of 480 degrees C in a mechanically stirred sand bed, which was connected directly to a fixed bed of catalyst particles for ex situ upgrading of the fast pyrolysis vapors. The carbon and mass yields in heavy phase liquids decreased after catalytic VPU (mass: ca. 8-11 wt %; carbon: ca. 11-15 wt %), compared to noncatalytic pyrolysis (mass: ca. 18 wt %; carbon: ca. 23 wt %). However, the yield in specific compounds, that is, alkylphenols and aromatics such as BTX, increased much upon catalytic VPU (especially for Fe/ZSM-5). For Fe/ZSM-5, the concentration in alkylphenols and aromatics was 20.8 wt % on liquid basis and the yield was 1.7 wt % on as-received (a.r.) feedstock basis. For noncatalytic pyrolysis, the concentration in alkylphenols and aromatics was 2.1 wt % (liquid basis) with a yield of 0.4 wt % (a.r. feedstock basis). This study thus demonstrates the potential of (modified) catalysts to upgrade lignin pyrolysis vapors.