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Abstrak :
The conventional method of generating energy is by means of combustion puts significant pressure on the environment. Therefore the study of gasification is needed. Low temperature gasification produces synthetic gas as a fuel or material to produce chemicals in industry. This study investigated the gasification characteristics of Victorian brown in terms of reaction competion and structural changes happen. It was found that as the concentration of oxygen reaches 5% and 6 second residence time, char yield goes to as low as 45 % to 25 %. , the char yield decreases, which indicates more synthetic gas was produced in the reaction. The structural changes of char during gasification were also observed, results shows the reaction mechanism of char as it goes through gasification. This is illustrated by the BET surface area, pore volume and also the pore size. In CO2 dominated reaction, the surface area goes as high as 240 m2/g to 180 m2/g due to char fragmentation and promptly decrease to around 170 m2/g, while in O2 reaction the surface area dropped to around 160 m2/g. SEM analysis shows considerable increase in the frequency of char particles which diameter smaller than 120 microns ( from 0.27 to 0.36 for particle smaller than 100 microns and from 0.28 to 0.35 for particle at 100 to 120 microns). While there is a noticeable decrease in the frequency of larger particle (0.26 to 0.19 for 120 to 140 microns, 0.09 to 0.06 for 140 to 160 microns and 0.1 to 0.03 for larger than 160 microns).

Abstrak :
Kebutuhan akan pemanfaatan EBT semakin meningkat dalam rangka mengurangi emisi fosil yang menyebabkan kenaikan suhu lingkungan secara signifikan. Salah satu potensi EBT yang dapat dikembangkan di Indonesia adalah EBT berbasis biomassa. Pemanfaatan biomassa hanya menyumbang 10% dari bauran EBT di Indonesia. Laboratorium Gasifikasi Universitas Indonesia memiliki alat Biomass Gasifier dengan kapasitas 10 kW listrik. Teknologi gasifikasi menggunakan jenis downdraft yang cocok digunakan untuk skala kecil. Alat tersebut dapat digunakan untuk langsung mengkonversi sekam mentah menjadi energi listrik maupun panas, namun belum diketahui kemampuan alat ini untuk bahan bakar lainnya. Sehingga penelitian ini berfokus untuk mengetahui mengetahui bahan bakar yang paling ekonomis sebagai bahan bakar. Parameter keekonomian yang digunakan pada penelitian ini yaitu menggunakan parameter LCOE, NPV, IRR, PBP, dan BCR. Hasil perhitungan menunjukkan bahwa biomassa ampas tebu memiliki keekonomian paling tinggi, dengan potensi energi listrik sebesar 18,50 kW memiliki nilai LCOE sebesar Rp 1.265,99/kWh dengan NPV positif, IRR 12,8%, PBP selama 5,48 tahun dan BCR 1,11. Berdasarkan analisa sensitivitas, parameter harga bahan bakar biomassa merupakan paling berpengaruh terhadap perubahan nilai LCOE sehingga pemilihan harga biomassa menjadi faktor utama yang mempengaruhi nilai keekonomian biomass gasifier. ...... The demand for the utilization of renewable energy sources is increasing to reduce fossil fuel emissions, which contribute significantly to environmental temperature rise. Biomass-based renewable energy technology holds great potential for development in Indonesia. However, biomass utilization currently accounts for only 10% of the overall renewable energy mix in the country. The Gasification Laboratory at the University of Indonesia has developed the Biomass Gasifier, a downdraft gasification technology suitable for small-scale applications, with an electrical capacity of 10 kW. This tool can directly convert raw rice husks into electrical energy and heat, but its performance with other fuel sources remains unknown. Therefore, this research aims to identify the most economically viable fuel source for the Biomass Gasifier. Economic parameters, such as Levelized Cost of Electricity (LCOE), Net Present Value (NPV), Internal Rate of Return (IRR), Payback Period (PBP), and Benefit-Cost Ratio (BCR), are employed to analyze the economic feasibility of different fuel options. The calculation results show that bagasse biomass has the highest economic potential, with a potential of 18.50 kW of electrical energy having an LCOE value of IDR 1,265.99/kWh with a positive NPV, IRR of 12.8%, PBP for 5.48 years and BCR 1,11. Based on the sensitivity analysis, the parameter of the price of biomass fuel has the most influence on changes in the value of LCOE so that the selection of the price of biomass is the main factor affecting the economic value of the biomass gasifier.

Abstrak :
Berkembang pesatnya aplikasi sumber energi baru-terbarukan di dunia khususnya Indonesia berpotensi memberikan dampak yang sangat besar bagi pemenuhan kebutuhan energi nasional. Energi biomassa yang tersimpan dalam senyawa kimia sekam padi memiliki ketersediaan yang berlimpah. Teknologi gasifikasi yang sudah dikembangkan oleh riset gasifikasi Universitas Indonesia memiliki salah satu permasalahan pada kualitas moisture sekam padi yang cenderung tinggi. Pembuatan alat pengering sekam diharapkan mampu menjadi penunjang ketersediaan energi, desain pengering konveksi dengan tipe pengering fluidisasi dan pemodelan pemanas LPG burner. Riset ini melakukan pengukuran pada proses drying rate sekam padi. Analisa dilakukan pada variasi suhu dan aliran udara terhadap waktu pengeringan. Perhitungan secara teoritis dilakukan dengan metode kesetimbangan energi dan kesetimbangan massa. Selanjutnya akan menghasilkan laju evaporasi. ...... Renewable energy research expansion in the world especially in Indonesia has given effects for national energy usage. Biomass energy which invested in the chemical compound of rice husk has a large availability. Gasification technology which has been developed has several problems, one of them is in the high moisture quality in rice husk. Fabrication of the dryer is expected can be a supporting systems in the biomass energy production. The dryer was designed for the convective dryer with the fluidized drying mechanism and LPG burner as a heater. This research measured on the drying rate of rice husk, analysis on the variation of temperature and air flow depends on drying period (time). Theoritically, energy balance and mass balance have been selected as a calculation methods. Finally, the drying rate will be converted into time period of drying on the bulk density variation.

Abstrak :
The increased need to reduce carbon dioxide emissions to prevent global warming have led to an interest in biomass and solid waste as fuel sources. As a potential renewable energy resource, biomass and solid waste materials are receiving more attention worldwide. A number of techniques and methods have been proposed for reducing gaseous emissions from a fossil fuel conversion thermal system. This paper presents a pilot-scale bubbling fluidized bed gasifier with a diameter of 0.68 m and a height of 1.50 m using an oil burner to heat the bed. This study used four types of biomass materials mixed with coal at different mass composition ratios in an air gasifying agent. The gasification tests were conducted under steady-state at an operating condition that is typical for gasification. The influence that the solid waste and coal ratio had on gasification efficiency was investigated. The gasification efficiency and the carbon conversion efficiency increased when the mass ratio of the solid waste fuels increased.

Abstrak :
Terdapat banyaknya limbah padat tandan kosong kelapa sawit yang belum dapat dimanfaatkan sebagai penghasil energi dikarenakan oleh tingginya kandungan moisture dan polusi yang dihasilkan apabila dibakar secara langsung. Penelitian ini bertujuan untuk memfabrikasi sebuah gasifier tipe unggun tetap aliran kebawah dan pemanfaatan limbah padat tandan kosong kelapa sawit untuk menghasilkan gas mampu bakar. Gasifkasi dilakukan mengunakan teknik percampuran dengan tempurung kelapa sawit. Percobaan dilakukan pada sebuah gasifier dengan kapasitas 6 kg/jam. Refraktori gasifier terbuat dari bahan castable dengan tinggi 70 cm, diameter 30 cm dan diameter tengorokan 12 cm. Kondisi operasi bertekanan dengan temperatur operasi 422°C-889°C. Tandan kosong dan tempurung yang digunakan mempunyai kandungan air 62,29% dan 8,5%. Perbandingan campuran tandan dan tempurung adalah 50%, 60%, dan 70% untuk tandan kosong dengan laju aliran udara pembakaran 157 lpm. Hasil percobaan menunjukkan campuran tandan kosong dan tempurung kelapa sawit dapat menghasilkan gas mampu bakar (CO, CH4, C2H4, H2, C3Hg ,C4H10). Variasi perbandingan tandan terhadap tempurung mempengaruhi temperatur gasifikasi dan kualitas gas yang dihasilkan. Kualitas gas paling baik didapat pada perbandingan 50% tandan kosong dengan nilai kalor 4,8 MJ/m3.

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The utilization of empty fruit bunches (EFB), as energy is very low since its moisture content high enough and also producing high pollution effect to environment when it burned through a direct combustion. The current research purpose is to design, fabricate and test a downdraft gasifier to gases or burn EFB under sub-stoichiometric condition. It is expected that this gasification process could produce a combustible gas as an alternative energy sources. During conducting the test, EFB is mixed by palm oil shell. Gasification reactor has capacity of 6 kg/h. Reactor refractory lining is a tastable material with of 70 cm height, 30 cm of diameter and 12 cm of throat diameter. During conducting the test, operational under pressure condition, working temperature 422°C- 889°C . EFB and shell has moisture contain of 62.29% and 8,5%, respectively. There 3 mixing ratio of EFB and shell, namely, 50%, 60% and 70% of EFB content and air flow rate 157 lpm. The result show that this mixing fuel could produce combustible gas (CO, CH4, C2H4, H2, C3H8 ,C4H10). Different EFB content influence gasification temperature and gas quality. The best quality is reached at 50% of EFB content with calorific gas value of 4.8 MJ/m3.

Abstrak :
Salah satu kendala yang menghambat program pengembangan gasifikasi biomassa sampai saat ini adalah gas produk gasifikasi siap pakai mengandung kadar tar diatas standar yang diijinkan yaitu <2 g/Nm3 (Energi Engineering- What is Gasification.htm). Sedang syarat yang ideal untuk berat kadar tar yang keluar gasifier tidak lebih dari 1% dari berat gas produk yang digunakan. Penelitian ini sebenarnya merupakan pengembangan penelitian dari tesis Saudara Fajri Vidian, 640202014Y, yang baru sampai tahap penelitian komposisi gas produk gasifikasi. Pengembangan penelitian yang dimaksud disini adalah memberikan penambahan udara pada udara pembakaran. Berdasarkan penelitian JH Howson, kandungan tar dalam gas secara proporsional dapat diturunkan dengan adanya penambahan udara. Oleh karenanya pengujian ini difokuskan untuk mengetahui seberapa besar pengaruh variasi kapasitas udara terhadap nilai kadar tar dan nilai kalor (CV) gas produk khususnya yang keluar dari gasifier dan perbandingannya terhadap standar yang ditetapkan. Dari hasil pengujian yang dilakukan ternyata didapatkan bahwa penggunaan lowrate udara bakar 413,73 lpm atau bukaan katup udara bakar 40° untuk proses gasifikasi biomassa 50% tandan kosong dan 50% tempurung kelapa sawit adalah yang mampu menghasilkan kualitas gas produk paling optimum. Penilaian ini didasarkan atas gas produk yang dihasilkan mempunyai nilai kalor tertinggi yaitu 13,307 MJ/m3 dan prosentase kadar tar di dalam gas produk yang bernilai 0,65%. Nilai ini dibawah dari standar ideal yang ditetapkan sebesar 1% berdasar berat.

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One of problem which to pursue the biomassa gasification development program until now is gasification that ready to use are containing tar more than 2 g/Nm3 (Energi Enginering - What is Gasification. htm) from standard allowed. The ideal criteria for tar contain of gasifier is not more than 1% from producer gas weight used. This examination is development from last tesis of Mr. Fajri Vidian, 640202014Y, just from composition exam of the producer gas. The development point of this examination is air addition of acombustion air. Based on JH Howson exam, tar contains on gas in proportional can reduced with air addition. Cause of that this exam focus on knowing the size can influence air flowrate variation with tar and calory (CV) specialy on producer gas. From experimental results that known if the addition of air significantly reduced the level of incondensable hydrocarbons (tar) of the gas. Using 413,73 lpm of the combustion air flowrate with ER = 0,62 resulted the optimum quality of producer gas. The producer gas have a caloricic value (CV) 13,307 MJ/m3 and a level of tar in the gas 0,65% by weight. Its under of 1% that is a standard level and a reasonable design basis for a downstream gas-treatment plant.

Abstrak :
Currently the world’s second largest palm oil producer Malaysia produces a large amount of oil palm biomass each year. Although some oil palm parts and derivatives like empty fruit bunch and fibre have been commercialized as fuel, less attention has been given to oil palm fronds (OPF). Initial feasibility and characterization studies of OPF showed that it is highly feasible as fuel for gasification to produce high value gaseous fuel or syngas. This paper discusses the experimental gasification attempt carried out on OPF using a 50 kW lab scale downdraft gasifier and its results. The conducted study focused on the temperature distributions within the reactor and the characteristics of the dynamic temperature profile for each temperature zones during operation. An average pyrolysis zone temperature of 324oC and an average oxidation zone temperature of 796oC were obtained over a total gasification period of 74 minutes. A maximum oxidation zone temperature of 952oC was obtained at 486 lpm inlet air flow rate and 10 kg/hr feedstock consumption rate. Stable bluish flare was produced for more than 70% of the total gasification time. Similar temperature profile was obtained comparing the results from OPF gasification with that of woody biomass. Furthermore, the successful ignition of the syngas produced from OPF gasification ascertained that OPF indeed has a higher potential as gasification feedstock. Hence, more detailed studies need to be done for better understanding in exploiting the biomass as a high prospect alternative energy solution. In addition, a study of the effect of initial moisture content of OPF feedstock on the temperature distribution profile along the gasifier bed showed that initial moisture content of feedstock in the range of 15% gives a satisfactory result, while experiments with feedstock having higher moisture content resulted in lower zone temperature values.

Abstrak :
ABSTRAK
Saat ini, konsumsi bahan bakar minyak Indonesia sangat tinggi. Di sisi lain, Indonesia menghasilkan limbah pertanian berupa jerami padi dalam jumlah yang besar. Limbah biomassa ini dapat dikonversi menjadi biometanol untuk dicampurkan dengan bahan bakar minyak fosil berangka oktan rendah Premium sehingga meningkatkan kualitas bahan bakar sekaligus mengurangi emisi gas rumah kaca. Jawa Barat merupakan provinsi dengan konsumsi bahan bakar Premium yang tinggi 5,24 juta kL/tahun sekaligus penghasil padi kedua terbesar di Indonesia. Dengan kondisi tersebut, penelitian ini dimaksudkan untuk merancang pabrik biometanol dari jerami padi pada skala komersil di Jawa Barat dengan gasifikasi teknologi Absorption Enhanced Reforming AER yang cocok untuk konversi biomassa dengan kandungan mineral tinggi. Penelitian ini melingkupi perancangan unit gasifikasi dengan menganalisis aspek mekanika fluida yang terjadi di dalam gasifier dan regenerator secara makroskopik, studi life cycle analysis LCA , serta perhitungan biaya produksi. Hasil penelitian menunjukkan bahwa secara teoritis, skala produksi biometanol dari jerami padi dapat mencapai 208.000 ton biometanol/tahun. Sedangkan, berdasarkan simulasi proses, biometanol hanya dapat dihasilkan sebesar 117.250 ton/tahun. Untuk proses produksi tersebut, dibutuhkan dimensi gasifier 3,2 m diameter 14,4 m tinggi dan combustor/regenerator 3,3 m/4,4 m diameter 12 m/42,9 m tinggi. Fossil energy ratio FER proses produksi tersebut adalah 0,6-1,06 dan masih ada CO2 yang diemisikan sebesar 2,7-3,7 kg CO2/kg biometanol. Biaya produksi biometanol dari jerami padi pada skala tersebut berkisar Rp 11.343-20.123/kg biometanol sehingga harga bahan bakar campuran adalah Rp 6.662-7.010/liter. Kata kunci: Biometanol; Jerami Padi; Gasifikasi; Absorption Enhanced Recovery.

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ABSTRACT
Currently, Indonesia consumes oil fuel in large amount. On the other side, Indonesia produces rice straw as agricultural waste in large amount. This biomass waste can be converted into biomethanol for fuel blending with low octane rating fossil fuel Premium , hence enhancing fossil fuel quality and reducing green house gas emission. West Java is a province with high fossil fuel consumption 5,24 million kL year and second largest rice producer in Indonesia. With this condition, this research is intended to design biomethanol plant from rice straw at commercial scale in West Java with gasification technology of Absorption Enhanced Reforming AER which is suitable to convert biomass with high mineral content. This research covers design of gasification unit by analyzing fluid mechanics inside gasifier and regenerator macroscopically, studying of life cycle analysis LCA , and production cost calculation. The research results in theoretically, biomethanol production scale from rice straw can reach 208.000 ton year. Meanwhile, based on process simulation, biomethanol can only be produced as much as 117.250 ton year. For the process production, required dimension of gasifier is 3,2 m diameter 14,4 m height and combustor regenerator is 3,3 m 4,4 m diameter 12 m 42,9 m height. Fossil energy ratio FER of the production is 0,6 1,06 and emitted CO2 of 2,7 3,7 kg CO2 kg biomethanol. Production cost of biomethanol from rice straw at the production scale is approximately Rp 11.343 20.123 kg biomethanol, hence blended fuel price is Rp 6.662 7.010 liter.

Abstrak :

Indonesia sebagai negeri agraris mayoritasnya menggunakan padi sebagai makanan pokok. Selain menjadi bahan makanan, padi juga dapat dimanfaatkan sebagai energi terbarukan salah satunya dengan menggunakan teknologi gasifikasi. Salah satu keuntungan teknologi ini adalah fleksibilitas produk syngas yang dapat dimanfaatkan langsung atau digabungkan dengan pembangkit listrik. Namun masih ada kendala besar sebelum dapat memanfaatkan syngas ini yaitu adanya tar yang tidak diinginkan. Sebelum dapat dimanfaatkan seperti masuk kedalam motor pembakaran dalam (Internal Combustion Engine ) tar perlu dikurangi kadarnya dengan beberapa metode, salah satunya adalah metode sekunder yaitu kondensasi. Metode ini dapat memisahkan tar dengan syngas berdasarkan titik embun tar. Pada penelitian ini akan dilakukan analisis senyawa tar yang terkondensasi dengan menggunakan aplikasi Computational Fluid Dynamic (CFD) Ansys Fluent 19.2 dengan menggunakan laju aliran 0,002 m³/s yang didapatkan dari hasil penelitian sebelumnya dan variable waktu pengambilan data dari rentan waktu 10 sampai 25 menit, 30 sampai 45 menit, 40 sampai 65 menit, dan 70 sampai 85 menit. Efisiensi pengurangan tar juga diteliti pada tiap-tiap variable tersebut dan dilihat karakteristiknya pada kondenser. Pengurangan tar tertinggi terjadi pada rentan waktu 70-85 menit, yaitu efisiensi pengurangan tar 64,46%.

 

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Indonesia as an agrarian country whose majority use rice as the main food. Besides food, rice could become a renewable energy resource by using gasification technology. One of the advantages of gasification technology is the flexibility of the producer gas so-called syngas. It could use in direct combustion and or coupled using the Internal Combustion Engine (IC Engine) for electricity. The biggest problem before it can be used is the presence of tar. Before it enters the IC Engine, it has to be removed using some methods, one of them is condensation. This method can separate tar with syngas based on tar dew point. In this study, the compounds of tars that condensed will be analysed using Computational Fluid Dynamic (CFD) Ansys Fluent 19.2 application with 0,002 m3/s from previous study and variable time with range 10-25 minute, 30-45 minute, 40-65 minute, dan 70-85 minute. Tar reduction efficiency was also examined in each of these time variables and the characteristics of the water condenser observed. The highest tar reduction occurs in the range of 70-85 minutes, which is the efficiency of tar reduction of 64,45%.

 

Abstrak :
Rice husk is one of the most abundant agricultural wastes in Indonesia, with an annual potency of 13,662 MWe. Using biomass gasification, it can be converted into producer gas, whose energy can be used for thermal and electrical power generation. In gasification terms, gas quality can be interpreted by tar content and gas energy. An experiment using an open top fixed bed downdraft gasifier (batch system) with double stage air supply was conducted by varying the secondary air injection position (Z) and the air ratio (AR). Tar content can be represented by flaming pyrolysis duration and gas quality by the combustion energy of the gas. Flaming pyrolysis is a phenomenon which occurs inside the reactor, where tar produced is re-cracked and dissolved into smaller compounds. This can be achieved if the pyrolysis zone temperature ranges between 500 and 800oC. With an AR of 80%, at Z = 38 cm, flaming pyrolysis with the longest duration of 400 seconds was created, which indicated that this condition had the lowest tar content; meanwhile, at Z = 50 cm, gas with the highest energy (734.64 kJ) was obtained.