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"Measurement of vapor flow in geothermal pipe faces great challenges due to fast fluids flow in high-temperature and high-pressure environment. In present study the flow rate measurement has been performed to characterization the geothermal vapor flow in a pipe. The experiment was carried out in a pipe which is connected to a geothermal production well, KMJ-14. The pipe has a 10” outside diameter and contains dry vapor at a pressure of 8 kg/cm2 and a temperature of 170 oC. Krypton-85 gas isotope (85Kr) has been injected into the pipe. Three collimated radiation detectors positioned respectively at 127, 177 and 227m from injection point were used to obtain experimental data which represent radiotracer residence time distribution (RTD) in the pipe. The last detector at the position of 227 m did not respond, which might be due to problems in cable connections. Flow properties calculated using mean residence time (MRT) shows that the flow rate of the vapor in pipe is 10.98 m/s, much faster than fluid flow commonly found in various industrial process plants. Best fitting evaluated using dedicated software developed by IAEA expert obtained the Péclet number Pe as 223. This means that the flow of vapor of geothermal fluids in pipe is plug flow in character. The molecular diffusion coefficient is 0.45 m2/s, calculated from the axial dispersion model"

"Kurangnya stabilitas oksidasi biodiesel menyebabkan banyak kendala dalam pemanfaatannya. Untuk mengatasi hal ini, stabilitas oksidasi biodiesel perlu ditingkatkan melalui proses hidrogenasi parsial yang dapat dilakukan dalam reaktor multifasa. Reaktor Slurry Bubble Column, salah satu jenis reaktor multifasa, yang telah banyak digunakan dalam proses hydrotreating, berpotensi untuk menyelenggarakan proses ini dalam sistem kontinyu. Akan tetapi, belum ada penelitian yang mempelajari penggunaan reaktor Slurry Bubble Column untuk mengubah biodiesel menjadi H-FAME melalui proses hidrogenasi parsial. Oleh karena itu, tujuan penelitian adalah untuk mengembangkan model matematis reaktor Slurry Bubble Column 2 dimensi axis-symmetric untuk proses hidrogenasi parsial. Model yang akan dibangun didasarkan pada persamaan kontinuitas untuk transport massa dan transport energi dengan modifikasi koefisien dispersi, juga penurunan tekanan dan distribusi katalis di sepanjang sumbu reaktor dan disimulasikan pada COMSOL MultiPhysic 5.4. Dalam penelitian ini, digunakan model kasus dasar reaktor kolom berbentuk silinder vertikal dua dimensi. Reaktor ini beroperasi pada 500 kPa, suhu saluran masuk 150 ° C. Umpan terdiri dari metil linoleat murni yang mewakili biodiesel dan hidrogen murni. Kecepatan gas masuk adalah 0,02 m/s, dan kecepatan cairan masuk adalah 0,00025 m/s. Hasil simulasi menunjukkan bahwa konversi metil-linoleat adalah 76,98%, hasil H-FAME adalah 54,8% berat, dengan kemurnian 54,45% berat.

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Biodiesel`s lacks of oxidation stability presents many constraints in its utilization. To enhance this property, biodiesel needs to be upgraded through partial hydrogenation process which can be carried out in a multiphase reactor. Slurry bubble column, a type of multiphase reactor, which has been widely used in hydro-treating process, has potential to perform this process in a continuous system. However, no previous studies had shown the usage of slurry bubble column for upgrading biodiesel to H-FAME via partial hydrogenation process. Therefore, this study purpose was to develop a two-dimensional axis-symmetric reactor model for this process. The model was based on equation of continuity on mass transport and energy transport with dispersion coefficient, also pressure drop and catalyst distribution along the reactor axis and simulated on COMSOL MultiPhysic 5.4. In this study, a base case model, two-dimensional, axis-symmetry, vertical cylinder-shape slurry bubble column reactor was used. This reactor operated in 500 kPa, inlet temperature of 150 °C. The feed consisted of pure methyl-linoleate as biodiesel representation and pure hydrogen. The inlet gas velocity was 0.02 m/s, and the inlet liquid velocity was 0.00025 m/s. Simulation results show that the conversion of methyl-linoleate was 76,98%, H-FAME yield was 54.8% wt, with 54.45% wt purity. Keywords: Biodiesel, Partial Hydrogenation, H-FAME, Slurry Bubble Column Reactor, dispersion model, COMSOL, multiphase, Methyl Linoleate."