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Prajitno, Hermawan,Park, Jongkeun,Ryu, Changkook,Park, Ho Young,Lim, Hyun Soo,Kim, Jaehoon Elsevier 2018 APPLIED ENERGY Vol.218 No.-
<P><B>Abstract</B></P> <P>In this study, the effects of product separation on the distribution of liquid products and the energy efficiency of sewage sludge liquefaction in supercritical alcohol and supercritical alcohol–water mixtures were investigated. While considering alcohol participation in the liquefaction reaction (6–47 wt%), the effects of process parameters such as temperature (300–400 °C), residence time (10–120 min), concentration (9.1–25.0 wt%), and type of supercritical fluid (water, methanol, ethanol, water–alcohol mixture) on the yield and properties of bio-oils were examined. Accounting for alcohol participation and product separation allowed the bio-oil yield, energy recovery, and energy efficiency to be newly defined. Application of the new separation protocol developed in this study realized a 10–25 wt% increase in bio-oil yield because light fractions were efficiently captured. When supercritical methanol was used, the light fractions consisted primarily of methylated short-chain esters, whereas ketones and alcohols were the major species when supercritical ethanol was used. Liquefaction at 400 °C and 20 wt% sewage sludge in a mixture of water–methanol (80:20, v/v) resulted in a bio-oil with a high calorific value (35.8 MJ kg<SUP>−1</SUP>), achieving 155% energy recovery and 106% energy efficiency. Computational fluid dynamics (CFD) analysis of bio-oil combustion conducted in a commercial boiler demonstrated that cofiring with a mixture of petroleum heavy oil and bio-oil resulted in a high firing temperature of 1570 °C and a heat transfer rate, which were comparable to that obtained from conventional heavy oil firing.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bio-oil was produced using liquefaction of sewage sludge in water-alcohol mixture. </LI> <LI> A sophisticated separation method was developed to capture light fractions. </LI> <LI> 10–25 wt% increase in bio-oil yield resulted because of captured light fractions. </LI> <LI> Amount of alcohol participated into reaction was 6–47 wt% depending on reactions. </LI> <LI> Considering light fractions/alcohol participation, energy efficiency was 106–114% </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
김수현,Hermawan Prajitno,유지호,김상도,전동혁,임정환,최호경,이시현,임혁 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-
Coal as catalytic support is advantageous in many respects. The pore structure and surface compositionare controllable, and the high thermal conductivity can increase the thermal efficiency of the reactor. It isstable in acidic or basic media and it is easy to recycle the catalyst after use. In this study, six differentcoals were evaluated as catalytic supports based on their ability to disperse of the metal and theircatalytic performance. Nickel particles with an average diameter of <11 nm are typically dispersed onlow-rank coals (LRCs). The nickel catalysts supported on LRCs show 60–70% hydrogen yield for methanolsteam reforming (MSR), and one of them maintained the activity during 1000 h continuous run,confirming the stability as catalyst support. Most of the well-known catalytic metals such as Pt, Pd, Rh,Ru, Mn, Co, Fe, Zn, Bi, Mo, K, Cu, Ce, Mg, Ga, and La, are dispersed on LRC (Eco coal) support uniformly withan average size of <10 nm. Much improved dispersion of the metals on LRC confirms the chance of havingimproved catalytic activity compared to the conventional carbon supports.
Jo, Heuntae,Prajitno, Hermawan,Zeb, Hassan,Kim, Jaehoon Elsevier 2017 Energy conversion and management Vol.148 No.-
<P><B>Abstract</B></P> <P>Herein, a supercritical methanol (scMeOH) route for efficient upgrading of the low-boiling fraction of fast pyrolysis bio-oil containing a large amount of low-molecular-weight acids and water was investigated. The effects of various reaction parameters, including the temperature, concentration, and time, were explored. The yield of bio-oil and the energy efficiency of the scMeOH upgrading process were determined based on the amount of methanol that participated in the reaction during upgrading and fractionation of the upgraded heavy-fraction bio-oils (UHBOs) and upgraded light-fraction bio-oils (ULBOs). Upgrading at 400°C with 9.1wt% bio-oil for 30min generated a high bio-oil yield of 78.4wt% with a low total acid number (TAN) of 4.0mg-KOH/g-oil and a higher heating value of 29.9MJkg<SUP>−1</SUP>. The energy recovery (ER) was 94–131% and the energy efficiency (EE) was in the range of 79–109% depending on the calorific values of the ULBOs. Compared with upgrading in supercritical ethanol and supercritical isopropanol, less alcohol participation, a lower TAN, and higher ER and EE were achieved with scMeOH upgrading. Plausible pathways for bio-oil upgrading in supercritical alcohols based on detailed compositional analysis of the UHBO, ULBO, and gaseous products were discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Non-catalytic and non-hydrogen based bio-oil upgrading was conducted using scMeOH. </LI> <LI> 16–40wt% alcohols were consumed during the upgrading. </LI> <LI> High bio-oil yield of 78.4wt% and low TAN of 4.0mg KOH/g were achieved. </LI> <LI> Effect of supercritical alcohols, reaction times, temperature and bio-oil concentration was conducted. </LI> <LI> scMeOH upgrading has good energy recovery (ER) and energy efficiency (EE) compared with scEtOH and scIPA. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Xuan Do, Truong,Prajitno, Hermawan,Lim, Young-Il,Kim, Jaehoon Elsevier 2019 The Journal of supercritical fluids Vol.150 No.-
<P><B>Abstract</B></P> <P>The solvothermal liquefaction of sewage sludge (SS) has received much attention as an ecofriendly method of liquid fuel production. In this study, we evaluated the economic feasibility of bio-heavy-oil (BHO) production from 100 t/d SS using supercritical ethanol (scEtOH) and methanol (scMeOH). The process included a dryer, supercritical reactor, BHO separator, steam boiler, wastewater treatment unit and storages. Two cases for the techno-economic analysis (TEA) were considered: BHO production with scEtOH (Case 1) and with scMeOH (Case 2). The four-level economic potential approach (4-level EP) was used for the TEA. The total capital investments of Cases 1 and 2 were 19.6 and 19.5 million dollars, respectively. Case 2 showed higher economic potential than Case 1 because of the low price of methanol. The BHO plant using scMeOH was economically feasible with a return on investment of 21%/a.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bio-heavy-oil (BHO) was produced by supercritical (SC) reaction of sewage sludge (SS). </LI> <LI> Process flow diagram for 100 t/d SS plants is proposed using SC ethanol and methanol. </LI> <LI> The BHO plant with SC methanol was more profitable than that with SC ethanol. </LI> <LI> The full-scale BHO plant with scMeOH showed economic feasibility with a 21% ROI. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>