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Abstrak :
Sampah padat kota (MSW) saat ini masih menjadi permasalahan dalam pengelolaannya. Sesuai dengan program pemerintah yang tertuang pada peraturan presiden nomor 35 tahun 2018 bahwa percepatan pembangunan pengolahan sampah menjadi energi listrik berbasis teknologi ramah lingkungan perlu dikembangkan. Salah satu teknologi untuk mengubah sampah menjadi energi terbarukan adalah menggunakan proses termokimia atau gasifikasi. Tujuan penelitian ini adalah menganalisis simulasi sampah padat kota (MSW) menggunakan fixed bed downdraft gasifier yaitu dengan cara menghitung neraca massa sampah padat kota (MSW) untuk dikonversi menjadi syngas sehingga diperoleh komposisi syngas, nilai kalor Low Heating Value (LHV), Cold Gasification Efficiency (CGE) dan daya gas engine. Analisis simulasi gasifikasi sampah padat kota (MSW) dengan fixed bed downdraft gasifier dilakukan dengan cara memberikan variasi air fuel ratio (AFR) sebesar 0,1 sampai 1,0 dan suhu pada 500-1000oC. Hasil analisis simulasi gasifikasi sampah padat kota (MSW) dengan fixed bed downdraft gasifier menghasilkan syngas dengan komposisi CO, CO2, H2, dan CH4 sebesar 24,78%, 18,65%, 15,6%, dan 4,06% serta nilai LHV dan CGE sebesar 6327,95 kJ/kg dan 39,73% pada AFR 0,3 suhu gasifikasi 600 oC dapat membangkitkan daya sebesar 400 kWe. ......Municipal solid waste (MSW) is still a problem in its management. In accordance with the government program contained in presidential regulation number 35 of 2018 that the acceleration of waste processing development into electric energy based on environmentally friendly technology needs to be developed. One of the technologies to convert waste into renewable energy is to use thermochemical processes or gasification. This study aims to simulation analysis of municipal solid waste (MSW) using fixed bed downdraft gasifier by calculating the mass balance of municipal solid waste (MSW) to be converted into syngas so that syngas composition, low heating value (LHV), Cold Gasification Efficiency (CGE) and power generator are obtained. Simulation analysis of municipal solid waste gasification (MSW) is done by providing a variation of air fuel ratio (AFR) of 0.1 to 1.0 and gasifier temperature at 500-1000oC. The result of simulatin analysis of municipal solid waste (MSW) with fixed bed downdraft gasifier produces syngas with composition are CO, CO2, H2, and CH4 of 24.78%, 18.65%, 15.6%, and 4.06%. Value of LHV and CGE of 6327.95 kJ/kg and 39.73% on AFR of 0.3 gasification temperature of 600 oC can power generator of 400 kWe.

Abstrak :
Sekam padi dan serbuk gergaji adalah biomassa yang melimpah di Indonesia sebagai negara agraris sehingga dapat dimanfaatkan dengan baik sebagai bahan bakar energi terbarukan pada proses gasifikasi. Tipe reaktor gasifikasi Fixed Bed Downdraft menjadi pilihan karena jenis reaktor yang sederhana, memungkinkan berbagai bahan bakar, dan menghasilkan syngas relatif bersih dengan kandungan tar dan partikel yang kecil sehingga memiliki efisiensi tinggi. Tujuan dari tesis ini adalah mengetahui nilai optimum kalor dan efisiensi termal pada variasi nilai rasio ekivalensi, suhu gasifikasi dan campuran sekam dan sebuk gergaji melalui proses simulasi berbasis semi kesetimbangan. Hasil simulasi data gas sintesis yang disajikan berupa CH4, H2, CO dan CO2 yang divalidasi dengan literatur eksperimen dan simulasi. Variabel terikat dalam tesis ini adalah laju alir massa feedstock senilai 1,7 kg/jam dengan variasi rasio ekivalensi 0,18, 0,23, 0,27, dan 0,31, variasi suhu gasifikasi 400oC hingga 1000oC dan variasi campuran umpan senilai 100% sekam, 75:25, 50:50, 25:75 dan 100% serbuk gergaji. Adapun olah data yang diperlukan yaitu menghitung rasio ekivalensi, berat molekul gas dan biomassa, densitas syngas, massa syngas per massa biomassa dan nilai Lower Heating Value (LHV). Pada akhirnya, hasil riset ini menunjukkan bahwa rasio ekivalensi optimum ditemukan senilai 0,27 dengan kalor syngas paling maksimum sebesar 3,05 MJ/kg untuk sekam dengan effsiensi 29,26% dan 4,99 MJ/kg untuk serbuk gergaji dengan effsiensi 34,51%. Sedangkan suhu optimum ditemukan senilai 700oC pada sekam dengan kalor syngas 3,38 MJ/kg effsiensi 32,36% dan 750oC pada serbuk gergaji sebesar 5,84 MJ/kg effisiensi 40,42%. Ditambah lagi seiring tambahan campuran 25% serbuk gergaji pada sekam dapat meningkatkan rata-rata kalor syngas dan termal effisiensi masing-masingnya sebesar 3% dan 1,93%. ......Rice husks and sawdust are abundant biomass in Indonesia as an agricultural country so that they can be utilized properly as renewable energy fuels in the gasification process. The Fixed Bed Downdraft gasification reactor type was chosen because the reactor type is simple, allows for a variety of feedstocks, and produces relatively clean producer gas with small tar and particle content so that it has high efficiency. The purpose of this research is to determine the optimum value of energy and thermal efficiency for variations of the equivalence ratio, gasification temperature and mixture of rice husks and sawdust through simulation process based a semi-equilibrium method. The results of the simulation of the syngas data presented the content of CH4, H2, CO and CO2 were validated by the experimental and simulation literature. The dependent variable in this research is the feedstock mass flow rate of 1.7 kg/hour with variations of the equivalence ratio of 0.18, 0.23, 0.27, and 0.31, the variation of the gasification temperature from 400oC to 1000oC and the variation of the feedstock mixture as 100% rice husk, 75:25, 50:50, 25:75 and 100% sawdust. Then data processing required is to calculate the equivalence ratio, gas and biomass molecular weight, syngas density, syngas mass per biomass mass and Lower Heaing Value (LHV) value. Finally, the results of this research showed that the optimum equivalence ratio was found to be 0.27 with the maximum syngas energy as 3.05 MJ/kg for husk with an efficiency of 29.26% and 4.99 MJ/kg for sawdust with an efficiency of 34, 51%. Meanwhile, the optimum temperature was found to be 700oC in husk with syngas energy of 3.38 MJ/kg efficiency of 32.36% and 750oC on sawdust of 5.84 MJ/kg efficiency of 40.42%. In addition, adding 25% sawdust to the rice husks can increase the average syngas energy and thermal efficiency by 13% and 1.93%, respectively.

Abstrak :
Penelitian ini memperlihatkan fenomena aliran fluida campuran antara udara dan gas sintetik di dalam cyclone gas burner. Pengamatan berfokus pada fenomena intensitas turbulen, energi kinetik turbulen, dan kecepatan aliran percampuran udara dan gas sintetik akibat variasi posisi inlet cyclone gas burner dengan pemodelan menggunakan ANSYS Fluent. Pengamatan pemodelan fenomena percampuran ini digunakan untuk melihat desain yang paling optimum untuk cyclone gas burner dengan debit konstan aliran udara dan gas sintetik masing-masing 11,38 x 10-4 m3/s dan 8,06 x 10-4 m3/s. Gas sintetik merupakan produk gasifikasi biomassa sekam padi tipe fixed bed downdraft gasifier dengan komposisinya 50% N2, 3% CH4, 18% H2, 19% CO, dan 10% CO2.

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This research showed the phenomena of fluid flow between the mixing flow between air and synthetic gas in cyclone gas burner. The observations focused on the phenomenon of turbulence intensity, turbulent kinetic energy, and the flow velocity of air and synthetic gas mixture as a result of variations in cyclone gas burner inlet position using ANSYS FLUENT modeling. Observating of mixing phenomena modeling is used to view the most optimum design for cyclone gas burner with constant air and synthetic gas each flow rates is 11,38 x 10-4 m3/s and 5,5 x 10-4 m3/s. Synthetic gas is rice husk biomass gasification product using fixed bed downdraft gasifier with 50% N2, 3% CH4, 18% H2, 19% CO, and 10% CO2 composition.

Abstrak :
Sekam padi merupakan salah satu biomassa yang memiliki potensi energi sebesar 3,84 GW. Dengan proses gasifikasi biomassa, sekam padi bisa menghasilkan energi. Tapi setelah proses gasifikasi, masih ada limbah berupa arang maupun abu sekam padi. Untuk menanggulanginya, unsur karbon dari limbah dimanfaatkan kembali. Penelitian ini menggunakan sistem batch fixed bed downdraft gasifier. Dengan memvariasikan posisi injeksi udara sekunder Z , didapatkan temperatur pirolisis yang berbeda. Karena perbedaan temperatur, didapatkan kandungan karbon dan jumlah massa limbah yang bervariasi. Hasilnya, saat Z = 34 cm kandungan karbonnya paling tinggi yaitu, 27,47 . Sedangkan saat Z = 46 cm kandungan karbonnya paling rendah yaitu, 22,11 . Ketika Z = 38 cm massa limbah yang dihasilkan paling rendah yaitu 27,4 dari massa awal.

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Rice husk is one of the biomass that has an energy potential of 3,84 GW. With the biomass gasification process, rice husk can produce energy. But after the gasification process, there is still waste either rice husk char or rice husk ash. To overcome it, the carbon element from waste is used. This research uses a fixed bed downdraft gasifier batch system. By varying the position of secondary air injections Z , obtain different pyrolysis temperatures. Due to the temperature difference, the carbon content and the amount of waste mass vary. The result, when Z 34 cm carbon content is the highest that is, 27,47 . When Z 46 cm carbon content is the lowest that is 22,11 . When Z 38 cm waste mass produced is the lowest 27,4 from the initial mass.

Abstrak :
Indonesia memiliki potensi limbah sekam padi yang cukup besar yaitu setara 150 GJ/tahun, sepertiga lebih dari potensi keseluruhan biomassa di Indonesia yaitu 470 GJ/tahun. Gasifikasi biomassa skala kecil tipe fixed bed downdraft menjadi salah satu solusi terbaik untuk memanfaatkan sekam padi menjadi energi untuk pembangkit listrik dan panas. Dari penelitian yang telah dilakukan di luar negeri dan dari penelitian sebelumnya, penggunaan secondary air intake pada reaktor terbukti efektif dalam mengurangi tar. Implementasi secondary air intake di posisi Z=38 cm tepat pada zona pirolisis, didapatkan hasil pada ER 0.25 mampu mengurangi tar sebanyak 80,82 dengan kandungan tar pada producer gas sebesar 11,62 gram/Nm3. Sementara pada ER 0,23 didapatkan nilai efisiensi gasifikasi tertinggi sebesar 33,41. ......Indonesia has a huge potential of rice husk waste that is equivalent to 150 GJ year, one third more than the overall potential of biomass in Indonesia of 470 GJ year. Small scale fixed bed downdraft biomass gasification is one of the best solutions to utilize rice husk to be energy for power and heat generation. From research that has been done abroad and from previous research, the use of secondary air intake at reactor proved effective in reducing tar. Implementation of secondary air intake in position Z 38 cm right on pyrolysis zone, obtained result at ER 0.25 able to reduce tar as much as 80,82 with tar content at gas producer equal to 11,62 gram Nm3. While at ER 0.23 obtained the highest gasification efficiency value of 33.41.

Abstrak :
Rice husk is one of the most abundant biomass wastes in Indonesia. One way to convert it into an alternative source of energy is biomass gasification. This is a thermochemical process which converts biomass feedstock into fuel gas or chemical feedstock gas (producer gas). The gasification type which is developed in this study is fixed bed downdraft type due to its low tar content and compatibility in microscale implementation. One major problem with the implemented biomass gasification reactor was ruggedness of the partial oxidation process due to the absence of air in the reactor?s middle section, which consequently affected the pyrolysis zone. Several experiments were conducted previously using coconut shells and rice husks as solid feedstock, where an equivalence ratio (ER) of 0.4 was obtained. Therefore, in order to optimize the pyrolysis zone, the modification conducted involves adding a circular air intake into the gasifier. Experiments were conducted in a pyrolysis temperature range of 300?700oC with ER variation of 0.19, 0.24, 0.27 and 0.31. The results show that a good quality producer gas is produced at an ER value of 0.24. This value shows a promising result because the ER value of biomass gasification standard is 0.25.

Abstrak :
Rice husk is one of the most abundant biomass wastes in Indonesia. One way to convert it into an alternative source of energy is biomass gasification. This is a thermochemical process which converts biomass feedstock into fuel gas or chemical feedstock gas (producer gas). The gasification type which is developed in this study is fixed bed downdraft type due to its low tar content and compatibility in microscale implementation. One major problem with the implemented biomass gasification reactor was ruggedness of the partial oxidation process due to the absence of air in the reactor’s middle section, which consequently affected the pyrolysis zone. Several experiments were conducted previously using coconut shells and rice husks as solid feedstock, where an equivalence ratio (ER) of 0.4 was obtained. Therefore, in order to optimize the pyrolysis zone, the modification conducted involves adding a circular air intake into the gasifier. Experiments were conducted in a pyrolysis temperature range of 300–700oC with ER variation of 0.19, 0.24, 0.27 and 0.31. The results show that a good quality producer gas is produced at an ER value of 0.24. This value shows a promising result because the ER value of biomass gasification standard is 0.25.

Abstrak :
ABSTRAK
Sekam padi merupakan limbah pertanian terbesar dengan potensi 13.662 MWe per tahun. Melalui proses gasifikasi biomassa, sekam padi dapat dikonversi menjadi producer gas yang dapat digunakan untuk kebutuhan energi panas maupun listrik. Untuk menghasilkan producer gas berkualitas baik, sistem gasifikasi dengan kandungan tar rendah menjadi fokus utama penelitian. Penelitian menggunakan open top fixed bed downdraft gasifier sistem batch dilakukan dengan memvariasikan posisi injeksi udara sekunder Z dan Air Ratio AR . Hasilnya, pada AR 80 , saat Z = 38 cm, tercipta flaming pyrolysis dengan durasi terpanjang selama 400 sekon yang mengindikasikan kandungan tar terendah, serta saat Z = 50 cm, dihasilkan producer gas dengan energi pembakaran tertinggi sebesar 734,64 kJ.

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ABSTRACT Rice husk is one of agricultural waste with the largest annual potency of 13,662 MWe. Using biomass gasification, rice husk can be converted into producer gas for thermal and electrical energy needs. In order to produce a good in quality producer gas, gasification with low tar content become the main focus in this research. Experiment using open top fixed bed downdraft gasifier batch system was conducted by variying the secondary air injection position Z and Air Ratio AR . As a result, when AR 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, producer gas with the highest combustion energy of 734.64 kJ was obtained