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Engineering and Applied Science Research, 50, 1, 82-91

Syngas from biomass gasification is being developed for alternative feedstock in the chemical industry. Palm kernel shell which is generated from palm oil industry can be potentially used as raw material for gasification process. The purpose of this study was to investigate the use of modified natural zeolite catalysts in steam gasification of palm kernel shells. Mordenite type zeolite was modified by acid leaching to be used as a tar cracking catalyst. Steam gasification was conducted at the temperature range of 750–850 °C and the steam to biomass ratio was in the range of 0–2.25. The result showed that steam gasification of palm kernel shell with the addition of zeolite catalyst at 750 °C and steam to biomass ratio 2.25 could reduce tar content up to 98% or became 0.7 g/Nm3. In this study, gasification of palm kernel shells produced syngas with the hydrogen concentration in the range of 52–64% and H2/CO ratio of 2.7–5.7. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

This research focuses on the properties and capabilities of carbon nanotubes (CNTs) as reinforcing agents in ceramic composite bearing components. The addition of CNT to pure ceramics can form composites with much better performance than conventional ceramics for various applications. The study was started from the pure ceramics in their use as a component of bearing total hip arthroplasty and the damage that occurred after implantation. The study covers factors that cause degradation of conventional ceramics introduction of properties and use of CNTs as new reinforcing agents for ceramic composite materials widely used sintering method and the heat and pressure parameters used during the sintering process to meet the standards for the manufacture of Total Hip Arthroplasty (THA) bearing component. The contact and buckling behaviors of the CNTs influence the composites friction properties. The presence of CNT until 20 wt% of CNT exhibited improve wear resistance with lower friction with the increase of weight percent. CNT reinforced ceramic coating might be capable to withstand high load-bearing conditions. Plastic deformation can be one of the critical processes in wear in the ceramics wear mechanism. Other processes are cracking and chemical reaction. The microstructures and porosity take an important role in indicating the ceramics wear properties and wear mechanisms.

Research on the application of chitosan as an edible film and coating has been developed. However, its hydrophilic nature causes edible films and coatings to be sensitive to air humidity so that they have a low moisture barrier. In addition, chitosan also has low thermal stability. This research combines natural rubber which is hydrophobic with relatively high thermal stability with chitosan which is antibacterial. The composite film between latex and chitosan was made by using the pour solution method. The occurrence of composites between latex and chitosan was proven from the results of FTIR and SEM characterization. The results of TGA characterization showed that the latex film (sample L1) had the highest thermal stability and the latex-chitosan composite (sample L1C3) had the lowest thermal stability. In the antibacterial test, it was concluded that the latex-chitosan film composite did not have bacteriocidal properties which was thought to be caused by the amine group in chitosan which could not diffuse on the media because it had formed a composite with latex. Based on the results of characterization and tests that have been carried out, it is concluded that the latex-chitosan composite film has thermal stability, optimal morphology in oxygen exchange with carbon dioxide, and has unmissable bacteriostatic properties. bacteria, liquid droplets, and moisturizers are samples of the L1C1 formula which is a sample with a 1% chitosan content. Keywords: Latex; Chitosan; Chitosan Latex Composite Film; Solution Casting; Thermal Stability; Antibacterial

Unit gasifikasi batubara jenis down draught kapasitas 100 kg/jam untuk mensubtitusi minyak bakar 70 liter/jam melalui proses gasifikasi, menggunakan udara-air sebagai medium penggasifikasi telah terinstalasi pada unit pengering di pabrik teh. Unit gasifiakasi terdiri dari reaktor gasifier, siklon, pendingin, kock out drum, blower dan burner. Gas produser stabil terbakar di burner, tetapi hanya mampu membuat udara panasdi unit pengering teh hingga 92oC (suhu target 100oC 120oC). Diperkirakan tidak tercapainya suhu target disebabkan kapasitas gasifier kurang besar, sehingga gas produser yang disuplai kurang dan pembakaran di burner selalu dalam ekses udara yang tinggi. Beberapa faktor gasifikasi yang diperkirakan mempengaruhi proses, antara lain: a. batubara pecah menjadi partikel lembut, menyebabkan penurunan tekanan yangmenghambataliran, hambatan aliran di ruang reduksi terjadi akibat pelelehan abu, menyebabkan penyumbatan aliran maupun penutupan arang, sehingga sulit bereaksi, c.kandungan tar masih banyak, karena tidak adanya scrubber yang dipasang di depan pendingin. Untuk menurunkan temperatur proses gasifikasi yang masih tinggi dan pelelehan abu diatasi dengan air yang disemburkan dalam bentuk kabut (spray) dalam daerah oksidasi melalui pemasangan pocker, penguapan air menyebabkan produksi hidrogen tinggi. Modifikasi lanjut difokuskan pada reaktor gasifikasi berupa perombakan throat (zona reduksi) untuk menurunkan temperatur proses dan meningkatkan pasokan gas hasil.

The cracking of real tar obtained from a pilot-scale gasifier of municipal solid waste was studied. The tar was both thermally and catalytically cracked under N2 atmosphere. Thermal cracking experi...

In this article, several reading theories need to be reviewed in their relationships to read understanding educators and English lecturers. Three other Reading Models, Bottom-Up, Top-Down, and Interactive, are discussed in the Schema Theory at the theoretical stage. The history of reading training, kinds and purposes of reading, and cognitive reading abilities will be discussed in checking the reading understanding. Finally, it reviews six variables that are engaged in understanding English texts. Keywords : comprehension, models of reading, schema theory Abstrak. Dalam artikel ini, beberapa teori bacaan perlu ditinjau dalam hubungannya untuk membaca pemahaman para pendidik dan dosen bahasa Inggris. Tiga Model Membaca diantaranyamodel Bottom-Up, Top-Down, dan Interactive dibahas dalam Schema Theory pada tahap teoretis. Rentetan uji coba, jenis dan tujuan membaca, serta kemampuan membaca kognitif dibahas dalam memastikan pemahaman membaca. Akhirnya, terdapat review terhadap enam variabel yang terlibat dalam memahami teks bahasa Inggris. Kata kunci: membaca, model membaca, teori schema

This study investigated the effect of pH and type of solvent on liquid-liquid phase equilibrium in the system of pure penicillin G and mixed penicillin G with 6-APA. Penicillin G extraction was carried out in a pH range of 2.0–5.0 at 4 oC using several types of solvents. The liquid-liquid phase equilibrium mathematical model is prepared assuming that a single stage of thermodynamic equilibrium occurs in a batch process of liquid-liquid extraction. The coefficient of activity was calculated by the UNIFAC method. From the experiment, it was found that the extraction process of penicillin G was strongly influenced by pH of the solution. The highest yield of extraction was achieved with different solvents in the two types of solution. For pure penicillin G system, the highest yields was obtained in n-butyl acetate solvent (95.51%) while for penicillin G mixture with 6-APA, it was obtained in methyl iso-butyl ketone solvent (92.6%). The UNIFAC model have been tested against five three-component liquid-liquid phase equilibrium systems at pH 2.0 and 2.5. It was able to estimate the concentration of penicillin G in the organic phase with a relatively average error between experiment and calculation of 8.32%

The palm oil industry is a promising biomass source, as the production generates wastes more than four times that of the main product. In 2020, for 45 MT of crude palm oil production in Indonesia, it was estimated that around 12 MT of palm kernel shell were generated or equivalent to 5.4 MTOE in net calorific value. This high calorific value of solid waste can be used by industries as a source of renewable energy, once it is proven to be technically, environmentally and economically feasible. In this comparative study, the life cycle assessment method was deployed to determine the environmental feasibility of palm kernel shell usage as an alternative renewable energy source to coal and natural gas in ceramic tile production through the application of combustion technology. The novelty of this study lies in a cradle-to-gate approach by comparing the carbon footprint of biomass from agriculture industrial waste with common fossil fuels as sources of energy for a highly energy-intensive industry. This research demonstrates that by evaluating the total life cycle of a fuel, the perspective on environmental impacts can be quite different when compared to looking solely at the end-use process. This study shows how the deployment of life cycle assessment would create managerial implications toward the decision making of fuel selection with carbon footprint considerations.

Rubber cone merupakan produk karet teknik yang digunakan sebagai mechanical seal part pada stuffing box pompa angguk sebagai peralatan utama untuk memompa crude oil dari dalam perut bumi sehingga keberadaannya begitu krusial dalam menentukan produksi yang akan dicapai. Dalam penggunaannya, rubber cone dikategorikan sebagai consummable part sehingga dibutuhkan dalam jumlah yang besar. Rubber Mechanical seal stuffing box pompa angguk saat ini sebagian besar berbahan baku karet sintetis NBR (rubber) yang mempunyai ketahanan yang baik terhadap gesekan dan minyak. Produk rubber cone berbahan baku karet alam yang dibuat diharapkan memenuhi spesifikasi teknis operasi pompa angguk yang bekerja pada kondisi beban tinggi, tahan terhadap gesekan serta tahan terhadap minyak dan temperature tinggi. Vulkanisat rubber cone bahan baku karet alam di uji untuk kemudian dibandingkan dengan spesifikasi teknis rubber cone komersiil. Uji kekuatan tarik dan kekerasan vulkanisat karet berdasar standar ASTM D412. Dari hasil uji ini diharapkan rubber cone karet alam dapat menggantikan rubber cone komersiil, sehingga mengurangi ketergantungan produk karet teknik impor.Â

Empty fruit bunch (EFB) is abundantly available for renewable energy resource, especially in Southeast Asian countries. However, EFB has inherent problems such as high moisture content, low heating value, and high alkali metal content. In order to improve the quality of feedstock as a fuel, in this research, the effects of hydrothermal treatment (HT) on the hydrothermally treated EFB (HT-EFB) characteristics were investigated. Also, the pyrolysis characteristics of EFB and HT-EFB were examined. The experiments of hydrothermal treatment were carried out in a 500-mL hydrothermal reactor at the temperature range of 120 to 220 °C with 60 to 120 min holding time. Afterward, the pyrolysis experiments of EFB and hydrothermally treated EFB (HT-EFB) were conducted in a lab-scale isothermal tube furnace at 400 °C for 1 h. The gas product was periodically collected to create gas evolution profiles. The result showed that hydrothermal treatment improved the properties of EFB, such as higher fixed carbon, lower ash content, and higher energy density. Hydrothermal treatment caused an increase in the heating value of HT-EFB to 19.47 MJ/kg, while the ratio of volatile matter/(volatile matter + fixed carbon) decreased from 0.82 to 0.68. Employing hydrothermal treatment in EFB did not only reduce the ash content of the biomass but also reduced the contents of potassium and sodium. In addition, the gas product from HT-EFB pyrolysis resulted in higher content of CO, CH4, and H2. The identified liquid product of pyrolysis consisted of alkane groups, phenolic groups, aromatic groups, ketones, acids, alcohols, and ester, which may be used as liquid fuel or for chemical production after further treatment. The observation indicated that hydrothermal treatment is an appropriate method to improve the fuel characteristic of EFB.

Sludge cake is a type of solid waste in pulp and paper mills which may harm the environment if disposed without treatment. Its proximate analysis (adb) are: ash 26.74%; volatile matter 59.09%; fixed carbon 11.04%; moisture 3.13%, while its ultimate analysis (adb) are: C 33.46%; H 4.5%; N 1.14%; S 0.35%; O 33.81%. Having a calorific value of 3000 cal/g (adb), sludge cake may be used as renewable fuel. Unfortunately it has a high water content, so reduction of water content become a main concern in utilizing sludge cake. A combination of mechanical dewatering and thermal drying has been considered for water removal with a minimum energy consumption. Moreover, the application of pressurized mechanical dewatering may also play a role in formation of briquettes.Experiments on mechanical dewatering and thermal drying were carried out using 50 g sludge cake with initial water content 73%. With a pressure of 400 kg/cm2 for compression, water content at the end of mechanical dewatering was 57%. This dewatered slugde was subsequently treated using thermal drying to a moisture content of 15%. Calculated total energy for this combination of mechanical dewatering and thermal drying was about 1080 J/g. This value was lower than the energy consumption of 1520 J/g required for direct thermal drying from its moisture content of 73% down to 15%. Experiments on the use of coal powder as compression aid were also trial to improve sludge dewaterability and briquettes calorific value. Mechanical dewatering of slugde with addition of 20%-w/w coal powder resulting a briquette with moisture content of 38% at compression pressure of 400 kg/cm2. The drying curves of briquette did not affected with its size if its diameter was less than 0.5 cm. Briquette with 1 cm thickness took significantly more time to remove its water content.

Experiments were carried out in a 500 mL digester at a temperature of 120, 150, or 180oC for a holding time of 60 min. The ratio of water to empty fruit bunch was 8 mL/gram. At these HT process conditions, proximate analysis, ultimate analysis and heating value of HT-EFB (solid product from HT) did not change significantly. However, the ash content in HT-EFB decreased significantly even from HT with a temperature of 120oC, from 3.20% to 1.9% for raw EFB to HT-EFB, respectively. Furthermore, K2O content in the ash in HT-EFB decreased significantly also, i.e. from 24% to 17%. Concerning with potassium, a longer holding time (HT at 120oC) could further decrease the potassium content in HT-EFB, from 16% to 9% for the holding time of 60 to 120 min, respectively. Since SiO2 dissolved very little in water while alkaline dissolved much more, silica content in the ash increased from about 44% in raw EFB to 53% in HT-EFB. In line with the change in the ash content and the mineral composition in the ash, the melting properties of ash in HT-EFB significantly changed.

In this paper, a conceptual process design of the integrated supercritical water gasification (SCWG) and reforming process for enhancing H2 production has been developed. The influence of several operating parameters including SCWG temperature, SCWG pressure, reforming temperature, reforming pressure and feed concentration on the syngas composition and process efficiency was investigated. In addition, the thermodynamic equilibrium calculations have been carried out based on Gibbs free energy minimization by using Aspen Plus. The results showed that the higher H2 production could be obtained at higher SCWG temperature, the H2 concentration increased from 5.40% at 400 °C to 38.95% at 600 °C. The lower feed concentration was found to be favorable for achieving hydrogen-rich gas. However, pressure of SCWG had insignificant effect on the syngas composition. The addition of reformer to the SCWG system enhanced H2 yield by converting high methane content in the syngas into H2. The modified SCWG enhanced the productivity of syngas to 151.12 kg/100kgfeed compared to 120.61 kg/100kgfeed of the conventional SCWG system. Furthermore, H2 yield and system efficiency increased significantly from 1.81 kg/100kgfeed and 9.18% to 8.91 kg/100kgfeed, and 45.09%, respectively, after the modification.

Before syngas from gasification of biomass could be used as synthesis fuel or chemical feedstock, it requires the removal of hydrogen sulfide (H2S) to meet the purity standard level of those applications. In this study, Zn-Fe/Al2O3 were successfully synthesized by a microwave-assisted wet incipient impregnation technique for use as adsorbent for H2S removal. The characterization of synthesized adsorbents showed that the oxide form of Zn and Fe present on the surface of adsorbents were zinc oxide (ZnO), magnetite (Fe3O4), and zinc ferrite (ZnFe2O4). While the reduction of adsorbent was mostly due to that of iron oxide. The reduced adsorbents might consist of ZnO/Fe3O4/FeO/Fe on alumina as support. At relatively high space velocity (26,000 h−1) the adsorbents were able to reduce the H2S concentration from 250 ppm at the inlet to around 45 ppm, 35 ppm, and 25 ppm at the outlet by adsorbent 1ZnFe, 2ZnFe, and 3ZnFe; respectively. The removal efficiency for adsorbent 1ZnFe, 2ZnFe, and 3ZnFe were 82%, 86%, and 90%; respectively. Results also shown an increase in adsorbent lifetime with the increase of the Zn to Fe ratio.

Gasification has been increasingly seen as a method to convert solid fuel into combustible syngas. However, these applications require syngas with strict requirements and raw syngas often does not meet these requirements. Therefore, a form of syngas upgrading needs to be applied. One of the most common form of syngas upgrading is removal of CO2, which is often present in large concentrations in raw syngas. The currently existing CO2 removal technologies were either designed not with syngas in mind or for large scale industries, which makes them somewhat inefficient for application with gasification syngas. This calls for more research into efficient removal of CO2, from syngas. In this review, the application of deep eutectic solvent (DES) as one of the potential new absorbent for CO2 removal from gas streams and more specifically from syngas are discussed. DES has garnered attention due to its high CO2 absorption performance, process friendliness, and environmental friendliness. At present, most studies on DES are still limited to basic absorption behavior of the absorbent. This review aims to provide not just a clear picture of the current research situation for DES as CO2 removal absorbent, but also detail the possible research directions that might be taken for the development of DES as CO2 absorbent from syngas. To that end, this paper shall discuss the specific situation of gasification development, syngas utilization, and the current DES research situation including: its advantages compared to conventional absorbents, its current research situation, challenges, and possible future research directions.

This study presents the relation of the biomass properties with the gasification performance. The potential of microalgae (N. oculta) for gasification also has been investigated. Other biomasses such as palm frond, mangrove, and rice husk were considered as the benchmarks. The performance of a combined gasification process for different biomass was evaluated by developing a thermodynamic model using Aspen Plus. The performance of gasification process was evaluated based on the composition of the producer gas, the cold gas efficiency, and the gasification system efficiency. The effects of biomass composition on the gasification performance was studied by varying the gasification temperature, the oxygen equivalence ratio, and the steam to carbon ratio. It was found that the H/O ratio in the feed biomass has a considerable effect on the H2/CO ratio of producer gas on the gasification without gasifying agent. The gasification of algae with oxygen exhibited the highest H2/CO ratio. The highest cold gas efficiency was found during gasification of algae with oxygen, while the highest cold gas efficiency from gasification with steam was exhibited on gasification of palm frond. The highest gasification system efficiency was obtained for palm frond using the oxygen or steam as the gasifying agent.

A new approach on thermodynamic simulation of the gasification process is conducted by considering the formation of tar using Aspen Plus. The present model shows higher accuracy as compared to the conventional model in term of the composition of producer gas. The tar from pyrolysis process is successfully reduced with high reaction temperature in the combustion zone. A parametric study is performed by varying the split ratio of gasifying agents (steam/oxygen) through three different zones: (i) combustion zone, (ii) counter-current reduction zone, and/or (iii) co-current reduction zone. Introduction of the gasifying agents through the counter-current reduction zone has positive effects on the gasification performances in term of hydrogen concentration, cold gas efficiency, and gasification system efficiency. The effects of O 2 equivalence ratio and steam to carbon ratio (S/C) on the performance of gasification are also investigated. The gasification with oxygen provided the highest cold gas efficiency. A remarkable hydrogen production is achieved from gasification with both oxygen and steam.

Investigasi proses gasifikasi dilakukan dengan pemodelan termodinamik. Kuantifikasi unjuk kerja proses gasifikasi dinyatakan dengan kadar H2 dan kadar CO dalam gas produser, temperatur dan efisiensi termal. Investigasi pengaruh kadar karbon terhadap unjuk kerja proses gasifikasi dilakukan dengan simulasi menggunakan batubara: lignit, bituminus dan antrasit. Ketiga jenis batubara diharapkan mewakili tingkatan kadar karbon. Kajian termodinamika digunakan sebagai piranti prediksi kinerja gasifikasi dan dapat melihat efek berbagai faktor secara cepat. Penyimpangan kinerja gasifier aktual terhadap hasil prediksi termodinamika sering ditemui dan biasanya dianggap sebagai akibat faktor-faktor teknis yang berhubungan dengan laju proses, misalnya pengontakan partikel dengan medium gasifikasi. Pada makalah ini, kajian termodinamika disempurnakan dengan melibatkan pemodelan dekomposisi batubara yang sangat tergantung pada jenis batubara dalam hal ini mewakili kadar karbon. Harapannya, pengabungan model dekomposisi batubara yang diusulkan dalam penelitian ini dan model kesetimbangan reaksi konvensional menghasilkan kajian termodinamika yang lebih rasional. Hasil dari kajian termodinamika digunakan sebagai piranti prediksi kinerja gasifikasi dengan mempertimbangkan kadar karbon batubara. Fraksi mol gas hidrogen maksimum yang dihasilkan lignit lebih tinggi daripada antrasit dan bituminus, berturut-turut 0,43 dan 0,25. Fraksi mol maksimum gas hidrogen dari lignit berada pada laju udara/batubara sekitar 1,2 kg/kg sedangkan antrasit dan bituminus berada pada sekitar 3 kg/kg. Temperatur proses gasifikasi, seperti diduga sangat dipengaruhi oleh jenis batubara. Sesuai dengan kadar H2, temperatur gasifikasi sebaiknya dijaga sekitar 1000 oC (Ru = 2,4 dan 4 berturut-turut untuk batubara lignit, antrasit dan bituminus). Keuntungan pada temperatur sekitar 1000 oC, tar secara praktis sudah terdekomposisi lebih lanjut, sehingga gas produser hanya sedikit mengandung tar.

National General Energy Plan of Indonesia 2017 (RUEN 2017) stated that dimethyl ether (DME) is appointed as a blending of LPG to reduce LPG imports. DME can be made with two reaction pathways, namely direct synthesis and indirect synthesis. The objective of this study was to determine the effect of pressure and syngas composition on the direct synthesis of DME using dual fixed bed catalyst. The research was carried out with two types of catalyst: M-xxx as a commercial catalyst for methanol synthesis and γ-Al2O3 as catalyst for dehydration of methanol to DME. The later was prepared in our Laboratory of Chemical Reaction Engineering and Catalysis, ITB. The dual catalyst experiment was carried out at 5 and 7 bars, and a fixed temperature of 240oC. The mass ratio of the M-xxx to γ-Al2O3, so-called M/D ratios, were varied from 1/9 to 9/1. Two type of syngas were used, i.e. SA containing only H2 and CO with a SN of 2,3 and SB containing 4% CO2 with SN of 1,8. The dual bed with a M/D ratio of 1/4 gave a CO conversion up to 62% at 5 bars and 240oC (SA). As pressure increased, the conversion of CO and H2 increases to 85% and 83% at 7 bar and 240oC (SA). The presence of CO2 (SB) decreases catalyst activity, as indicated by the decrease in conversion of CO and H2 to 56% and 54%, at 7 bar and 240oC.

In securing future energy supply and reducing the environmental impact due to the use of fossil fuels, the research on waste to energy conversion has been encouraged. The development of biomass or waste utilization processes has been supported by numerous experimental work and process modeling. Owing to the increasing interest in waste-to-energy research, several process models have been developed to evaluate process performance. This chapter presents the discussion on several works that used Aspen Plus simulator software to establish a process modeling approach. The results has revealed the great potential of Aspen Plus for evaluating the processes of waste-to-energy plants.

A research on the production of dimethyl ether (DME) at lower pressure has been conducted in related to the national program on the partial substitution of LPG with DME in the near future (RUEN 2017). DME may be liquefied at a pressure of about 6 atm (25°C), or a temperature of -25°C (1 bar). Burning of DME may produce a cleaner flue gas than LPG. Experiments on dehydration of methanol to produce DME were carried out at a atmospheric pressure (1 bar) and a temperature of 240°C. The experiment was conducted in a tubular reactor with a diameter of 20 mm. and three types of catalyst, i.e. g-Al2O3 (from our laboratory), and two commercial catalysts namely catalyst A and catalyst B. The γ-Al2O3 catalyst had a surface area of 194.4 m2/gram, an average pore diameter of 11.2 nm, and a total pore volume of 0.546 mL/gram. Methanol concentration in the influent of the reactor was 0.02 mol/L, 0.05 or 0.07 mol/L. It was found that g-Al2O3 catalyst had a better activity than the two commercial catalysts. A stable conversion of methanol of 72% was obtained on g-Al2O3 catalyst for the on-stream time of 6 to 10 hour. Kinetics of dehydration of methanol to DME on γ- Al2O3 catalyst could be represented as a first order reaction with an activation energy Ea of 256.6 kJ/mol and a frequency factor ko of 8·10+28.

Empty fruit bunch (EFB) is a potentially new and renewable feedstock for gasification process to produce synthesis gas. Unfortunately, it has a low bulk density, high moisture content, and high ash content. So a pretreatment is needed for its utilization as a solid fuel. By using hydrothermal treatment (HT), the characteristic of EFB can be improved such as decreased ash content, easily dried, size reduction and subsequent pelletization. The hydrothermal treatment was conducted at 200°C and 60 min. The solid product of HT was then pressed with a pressure up to 500 bar to get pellets with a diameter of about 1.0 cm and a thickness of about 0.5 cm. Experiments on steam gasification of HT-EFB pellet were carried out in a tubular reactor at a temperature of around 700°C. Before gasification, the pellets were heated up to 400°C to let the EFB undergo pyrolysis. Steam with a flow rate of 30 g/h was introduced when bed temperature achieved 700°C. Nitrogen was used as an internal standard and was introduced at a rate of 100 mL/min. After normalization excluding N2, the composition of synthesis gas obtained from gasification was more or less as follows: 65%-mol H2, 25%-mol CO and 10%-mol CO2. The composition of synthesis gas was naturally depended on the gasification temperature and the ratio of steam to pellets. Surprisingly, the form and size of the residue after the gasification process was still similar to pellets, but very porous.

Dimethyl ether (DME) is already used as a propellant and intermediate chemicals. Now, Indonesia will use DME as alternative energy for Liquid Petroleum Gas (LPG), as a result of the continued increase in LPG imports. In this study, DME was synthesized by dehydration of methanol process. The y-Al2O3 and modified CuO/y-Al2O3 ITB use as catalysts for the process. The objective of this research was to compare of catalytic activity of two catalysts at methanol dehydration to DME. The catalyst activity test was carried out in a tubular fixed-bed reactor (ID 1 cm and length 21 cm). Methanol dehydration was carried out at 1 bar, GHSV 1,100-2,200/h, methanol 1.9-4 mL/h, N2 10-30 mL/min (27.5°C and 0.93 bar). The downstream gas of the reactor was analyzed using gas chromatography and the condensate was analyzed using a refractometer. The y-Al2O3-ITB catalyst gives the highest performance with 89.6% of methanol conversion, 6.6% of DME yield, and 16.6% of DME selectivity. Whereas CuO/y-Al2O3 catalyst has a lower performance by 85.5% of methanol conversion, 1.4% of DME yield, and 3.7% of DME selectivity.

Conversion of fallen leaves and twigs from urban waste into pellets may be one of several options to reduce the amount of waste transported to the landfill. However, the production of pellet needs very high mechanical energy or electricity. A case study has been conducted to evaluate the advantages and disadvantages of integrating a gasification technique into the production unit. In this integrated unit, the source of electricity for the pellet production was based on the conversion of a portion of pellet product to gaseous fuel which was then used as substitute of diesel fuel for running an electricity generator set. Three scenarios for supplying the electricity were compared: (i) scenario-A: from PLN (national grid, coal fired power plant), (ii) scenario-B: diesel-generator set; and (iii) scenario-C: diesel-genset and gasification unit. Total CO2 emissions in the production of pellet were as follows (kg CO2 eq /ton pellet): 81.8, 47.2 and 16.3 for scenario-A, B and C respectively. Due to the addition cost of investment, the integrated pellet production and gasification unit needed a Payback Period of about 5.6 years, while those of diesel based electricity and PLN were 5.1 and 4.8 years respectively. Data for this study was obtained from experiments on a pellet production unit with a design capacity of about 9 ton/week. The diesel engine was run in dual fuel mode using producer gas from the gasification of pellet. The producer gas heating values were in the range of 3300-4600 kJ/Nm3. Oil saving in dual fuel operation was up to 70%.

Potassium content in biomass ashes, especially empty fruit bunches was quite high and had not been utilized maximally. This research dealt with the development of a technique for recovering potassium salt from a solution of ash extraction. Experiments were carried out usung a solution model containing KCl, NaCl, MgCl2, and CaCl2 with concentrations of 164.19, 8.39, 7.44, dan 39.60 mg/L respectively. Results of a preliminary experiment indicated that the solubilities of KCl and NaCl were reversed: 280.4 and 280.4 (g/L in water) to 6.9 and 14.2 (g/L in absolute ethanol), while the solubilities of MgCl2 and CaCl2 were still high (68.7 and 383.5 g/L in ethanol). Using these values of solubility, a combined evaporation and adding ethanol was trialed firstly to increase the precipitation of KCl. Evaporation of KCl solution 164.19 g/L until an evaporation leves of 15% did not give any precipitation yet, while adding ethanol to the remaining solution (at solution ratios of 4/1 and 3/2 ethanol) yielded precipitations with the potassium recoveries of 60% and 48% respectively. At an evaporation level of 30%, the evaporation yielded a 5% potassium recovery, while the combined technique gave 60% and 50% recoveries for adding ethanol with ratios of 4/1 and 3/2 respectively. The application of the combined technique on the mixed salts solution was modified slightly. The precipitate from the evaporation (containing KCl and NaCl) was redissolved into water and followed by adding ethanol to precipitate only KCl. Thus, two precipitates were finally obtained: (i) precipitate from adding ethanol to filtrate of evaporation, and (ii) precipitate from dissolving precipitate from evaporation. At an evaporation level of 30%, the evaporation only gave a precipitate recovery of about 10%, while the application of combined technique gave bout 80% and 60% recoveries by adding ethanol with ratios of 4/1 and 3/2 respectively. Hopefully this technique could separate KCl from its mixture with NaCl, MgCl2, and CaCl2.

Cu/ZnO catalyst was succesfully prepared using a coprecipitation method. The mixing procedure of the Cu(NO 3 ) 2 , Zn(NO 3 ) 2 and Na 2 CO 3 solutions had an important influence on the characteristics of the catalyst. The best catalyst obtained was the one prepared with slow mixing of the salt solutions and a CuO/ZnO molar ratio of 50:50. This raw catalyst had a maximum surface area of about 61.6 m 2 /g. Increasing the CuO/ZnO molar ratio caused an agglomeration of precipitated particles, reducing the surface area. A much better catalyst was obtained using an impregnation method, in which g-Al 2 O 3 was used as support. The impregnated catalyst had a surface area of about 151 m 2 /g. Activity tests were carried out in a fixed-bed reactor containing 1 g of catalyst and a flow of syngas at a rate of 60 mL/min. The reaction temperature was 170°C and the pressure was 20 barg. The best coprecipitated catalyst gave a CO conversion of about 10%, while the impregnated catalyst gave a CO conversion of up to 69%.

This study explored the feasibility of biomass CO 2 gasification as an effective method for implementing the concept of a carbon-negative power system through bioenergy with carbon capturing and storage. A CO 2 -recycling biomass gasification system was developed and examined using the thermal equilibrium model. Sensitivity analysis was performed by varying the gasifier temperature from 750 to 950 °C, and the turbine inlet temperature (TIT) and turbine exit temperature (TET) of the gas turbine from 1000 to 1200 °C and from 900 to 1000 °C, respectively. The gasifier efficiency was increased by an increase in the CO 2 recycling ratio with the more significant trend shown at the lower gasifier temperature. The turbine efficiency decreased as the CO 2 recycling ratio to the gasifier increased over a certain limit, a ratio of 0.55 in most cases. A pressure ratio of 2.3 was optimum in terms of turbine efficiency. Under the examined conditions, the optimum conditions for gaining the highest system efficiency, 39.03%, were a recycling ratio of 0.55 and a TET and TIT of 1000 and 1200 °C respectively. The proposed system had 7.57% higher efficiency and exhausted 299.15 g CO 2 /kW h less CO 2 emissions than conventional air gasification. Combined with carbon capturing and storage, the system potentially generates carbon-negative power generation with intensity of around 1.55-kg CO 2 /kg wet-biomass and a maximum efficiency penalty of 6.89%.

A clear understanding of the basic characteristics of municipal solid waste is the basis for the investigation of appropriate disposal technique. Municipal solid wastes subdivided into 7 categories were sampled in 7 typical cities of Indonesia in this study. The physical composition, chemical properties of the municipal solid waste, as well as the impact of seasonal and geographical changes on the physical composition have been investigated. The physical and chemical characteristics of municipal solid waste in Indonesia is understood in detail.The average percent content of each Indonesian waste category in sequence is 27.50% food waste, 20.42% mixture waste, 19.41% plastic waste, 14.54% paper waste, 9.25% wood waste, 4.90% textile waste, and 3.98% non-combustible waste. It is found that the seasonal changes have weak impact on the composition of MSW in Indonesia. The moisture content of each type of waste is above 30%, and the lower heating value on a wet basis of the overall municipal solid waste reaches 8.6MJ/Kg, which is well above the World Bank-recommended value (6MJ/Kg) for utilization in thermochemical conversion processes. The results prove that Indonesian municipal solid waste is potential for converting waste to renewable power or other energy products.

Palm oil empty fruit bunch (EFB) is a by-product produced during palm oil processing. In South East Asian countries, EFB is abundant and can be utilized as a renewable energy source. Cofiring of EFB with coal can be beneficial for preserving coal and reducing CO2 emission. However, EFB has some weaknesses in its properties such as; low bulk density, high moisture content, high alkaline contents, etc. Moreover, high amount of silicon and potassium in EFB tend to increase ash agglomeration which causes slagging and fouling in the equipment. In this study, hydrothermal treatment (HT) was employed to improve the physicochemical properties of the EFB by turning into biochar. Biochars are obtained after EFB is treated hydrothermally at a temperature range of 200-300 oC for 60 minutes were characterized for their proximate and ultimate compositions, mineral composition, calorific values, and ash fusion temperature. The analyses showed that fixed carbon increased while volatile matter decreased after HT. These changes were more prominent with increasing reaction temperature. The calorific values of EFB increased from 19.05 MJ/kg to 29.31 MJ/kg after HT at 300 oC. The biochar was then mixed with coal at different ratios (1:1, 1:2, and 2:1) for cofiring. The results showed that the energy densification increased with increasing reaction temperature. XRF results showed that the contents of Na, K and Si in EFB decreased after HT, resulting in the increased ash melting temperature. Consequently, the fouling and agglomeration potential could be reduced. The optimum ratio for cofiring between biochar and coal was found to be 2:1, as the fouling and slagging indices were lowest. It can be concluded that HT is a promising method for upgrading EFB as a feedstock for cofiring with coal.

National Plan on Energy of Indonesia 2017 states that dimethyl ether (DME, CH3OCH3) will be used as partial substitution of LPG for household fuel. Methanol dehydration using a solid catalyst is a common technology to produce DME. In this research, a catalyst γAl2O3 prepared in our laboratory has been characterized. This catalyst had a surface area of 194.4 m2/g, a total pore volume of 0.55 mL/g, and an average pore diameter of 112, 3 A˙. This catalyst had medium and high acidity sites. Activity tests of this catalyst were carried out in a fixed bed reactor at temperatures of 240, 260 and 280°C. The gas flow rates were related to the gas hourly space velocity of 1500, 2142 and 3000 h−1. Experimentally, the conversions of methanol were closed to that of thermodynamic conversions, i.e about 90% depending on the reaction temperature. The outlet gas was found to contain H2 up to 2% indicating that there were side reactions besides the dehydration of methanol to DME.

One of the problems faced by PLN is the high non-technical shrinkage of potential AMR customers due to installation and maintenance errors. This problem certainly has a solution that can be used so that non-technical losses can be suppressed. Based on the theory of electric energy calculation, from the voltage, current and power factor, it can be seen that the energy consumption is calculated or paid every month. Then done using the AMR application to monitor and analyze the use of electrical energy to potential customers with known data sources. Monitoring with this AMR application can make it easier to determine electrical energy deviations that have not been measured by the kWh meter, so as to accelerate normalization in case of errors or anomalies in the kWh meter. The results of the study explained that an abnormality was found due to the reverse polarity of the CT causing losses to the PLN which resulted in a subsequent bill of PT. Tjokro Bersaudara Bontang Kaltim Rp. 134,902,352.00.