Browsing by Author "Setyawan, Hendrix Yulis"

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    Cenosphere formation and combustion characteristics of single droplets of vacuum residual oils
    (Taylor and Francis, 2023-01-17) Setyawan, Hendrix Yulis; Zhu, Mingming
    The ignition, combustion characteristics, and cenosphere formation of single droplets combustion of four vacuum residues (VRs) from different refineries with various asphaltene contents were studied experimentally. The single droplets of VRs were suspended at the tip of a silicon carbide fiber and heated in air at temperatures of 973 and 1023 K, respectively, in an electrically heated tube furnace. The ignition and combustion behavior of the VRs were recorded using a CCD camera, which enabled the determination of droplet size, ignition delay time, flame duration, and cenosphere size. The effect of initial droplet size, gas temperature, and asphaltene content on the ignition delay time, flame duration, cenosphere morphology, and particle size were investigated. The whole ignition and combustion process of single droplets of the VRs consisted of five stages in succession: (1) pre-ignition, mainly involving the evaporation of highly volatile components from the droplet surface; (2) steady combustion of fuel vapors evaporated from the droplet surface; (3) splashing combustion of fuel vapors evaporated from droplet interior; (4) disruptive combustion due to thermal decomposition of asphaltene; and (5) solid residue ignition and combustion. A visible and sooty flame was formed upon ignition and lasted during stages 2–4. The droplet size increased sharply in the stage 4 due to the thermal decomposition of asphaltene, which was more profound for VRs with higher asphaltene content and at higher gas temperatures. The ignition delay time increased with increasing initial droplet size and gas temperature but varied little as the asphaltene content in the VRs increased, suggesting that the ignition process of VRs was controlled by the vaporization of high volatile components on the droplet surface. The thermal decomposition of asphaltene produced solid residue, which was in the form of a cenosphere with the shell thickness being ca. 20 μm and a number of blowholes presented in the shell. The VRs with higher asphaltene content had more and bigger blowholes. The ratio of cenosphere particle size to initial droplet size is independent of the initial droplet size but almost increased linearly with the asphaltene content in the VRs.
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    Effect of biochar addition on biogas production using konjac waste through mesophilic two-phase anaerobic digestion
    (Springer, 2024-08-29) Sugiarto, Yusron; Ahmad, Ary Mustofa; Setyaningsih, Yeni Ika; Maharsih, Inggit Kresna; Sunyoto, Nimas Mayang Sabrina; Setyawan, Hendrix Yulis; Zhu, Mingming
    Purpose: This study aimed to investigate the influence of biochar supplementation in the mesophilic two-phase anaerobic digestion process for konjac waste. Methods: Reactors with a working volume of 60 mL were utilised to incubate cultures containing biochar. In the first phase, the cultures were maintained at 32 °C and a pH of 5 to facilitate the production of hydrogen. In the second phase, the cultures were adjusted to 37 °C and a pH of 7 to promote methane production. The concentration of konjac flour waste varied between 0 and 500 g/L, while the ratio of biochar addition ranged from 0 to 25 g/L. Biogas production was measured daily using the volume displacement method, and the pH of the cultures was monitored both before and after the experiment. Results: The findings show that using biochar has a beneficial effect on biogas production from konjac flour waste. During the initial phase of the experiment, incorporating biochar with a concentration of 15 g/L led to substantial improvements, elevating the maximum H2 production rates by 9.6%. Furthermore, the addition of biochar led to an 84% increase in H2 yield during the initial phase. Similarly, in the second phase, introducing biochar with a concentration of 15 g/L resulted in a 22.2% increase in the maximum CH4 production rates and a 2.5 times increase in CH4 yield. Conclusions: Overall, this work confirms the beneficial effects of biochar on the H2 and CH4 production from konjac flour waste using the mesophilic two-phase anaerobic digestion method for sustainable energy.
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    Properties and combustion characteristics of bioslurry fuels from agricultural waste pyrolysis
    (Taylor & Francis, 2024-07-30) Setyawan, Hendrix Yulis; Zhu, Mingming
    The current research investigates the combustion characteristics of bioslurry fuel derived from the products of agricultural waste pyrolysis. The bioslurry fuel was prepared by mixing biochar and pyrolysis oil. The combustion characteristics of a suspended single droplet of the bioslurry were analysed. The results indicate that an increase in pyrolysis temperature (400–600°C) lead to higher concentrations of fixed carbon (56–60%), increased ash content (16–18%), and higher calorific values (25–32 MJkg−1). As the pyrolysis temperature rises, the biochar surface becomes more porous, lower volatile matter content and particle size. As biochar content increases, the bioslurry’s density, viscosity, and caloric value increase but stability index decreases. Higher biochar content in the bioslurry increases the ignition delay and burnout time while reducing the burning rate. The bioslurry fuel contained 30% biochar achieved a calorific value of 28 MJkg−1 and a viscosity of 600 cP, comparative to conventional fossil fuels.