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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.

Abstrak :
Minyak atsiri merupakan senyawa penting dalam bahan alam, yang memiliki banyak khasiat bagi kesehatan manusia. Minyak atsiri dapat diambil dari bahan alam dengan proses ekstraksi. Salah satu proses ekstraksi yang sedang menjadi tren penelitian adalah ekstraksi ultrasonik, yang dinilai memiliki banyak keunggulan, seperti kemudahan operasi, energi yang relatif rendah, dan operasi pada temperatur rendah yang dapat menjaga stabilitas senyawa biokimia dalam bunga telang. Salah satu kebaruan dalam penelitian ini adalah adanya penambahan mekanisme probe yang bergerak secara oksilasi, memungkinkan sumber gelombang ultrasonik menjadi dinamis. Selain itu, juga ditambahkan variasi intensitas ultrasonik sebagai parameter optimasi universal dalam ekstraksi ultrasonik. Adapun metode yang digunakan dalam analisis adalah metode kuantitatif dengan pengukuran data-data temperatur dan perhitungan fraksi massa minyak atsiri sebagai representasi kuantitas minyak atsiri, metode kualitatif dengan analisis visual perubahan warna emulsi dan distribusi temperatur terhadap waktu, serta metode analitik dengan perhitungan kinetik proses ekstraksi ultrasonik, untuk mengetahui nilai yield, yang direpresentasikan oleh kuantitas senyawa phenolic dengan perhitungan konstanta Peleg. Hasil penelitian menunjukkan bahwa, dengan penambahan probe oksilasi, dapat menyeragamkan distribusi temperatur dan ikatan antara pelarut dan senyawa biokimia dalam bahan alam, atau dengan kata lain, meningkatkan kualitas minyak atsiri yang dihasilkan. Di sisi lain, intensitas ultrasonik yang semakin tinggi dapat meningkatkan volume minyak atsiri yang dihasilkan, yang direpsentasikan fraksi massa minyak atsiri dan analisis kinetik yield terhadap waktu, serta meningkatkan laju ekstraksi yang terlihat dari analisis kinetik dan perubahan warna emulsi terhadap waktu. Hal ini disebabkan karena intensitas ultrasonik meningkatkan efek sonokemistri, kavitasi, turbulensi dan tegangan geser yang meningkatkan kuantitas dan laju ekstraksi. Hal penting yang harus diperhatikan dalam optimasi proses ekstraksi ultrasonik adalah turbulensi yang terlalu tinggi dapat menyebabkan agitasi dan temperatur yang terlalu tinggi dapat berpotensi merusak senyawa biokimia aktif dalam bunga telang. ......Essential oil is an important compound in natural substances, which has many benefits for human health. Essential oil can be produced from natural substances through the process of extraction. One of the trending extraction processes is ultrasonic extraction, which is considered to have many advantages, including, ease of operation, relatively low energi consumption, and capability to operate at low temperature which keep stabilitizing biochemical compounds inside natural substances, which in this research used butterfly pea flower (Clitoria Ternatea L). The novelty of this research was the application of a mechanism of osscilating moving probe, enabling ultrasonic wave source to be dynamic. Additionally, varieties of ultrasonic intensities was also applied as an universal parameter in optimizing the process of ultrasonic extraction. The methods used in the research were quantitative methods by measuring data of temperatures and calculating essential oil mass fraction, as representatives of essential oil quantity, qualitative methods by visual analysis of emulsion color evolution and temperature distribution through time, as well as analytical method by calculating the kinetics of ultrasonic extraction process, to determine yield, represented by phenolic compound quantity with Peleg’s constant calculation. The results of the research showed that oscilating probe addition could evenly distribute temperature and enhanced the bonds between solvent and biochemical compounds inside the natural substances, in other words, improving the quality of essential oil produced. On the other hand, a rise in ultrasonic intensities could increase essential oil volume produced, which was represented by essential oil mass fraction and kinetic analysis of yield through time, as well as increasing the extraction rate, as shown in kinetic analysis and emulsion color evolution. This was due to higher ultrasonic intensities enhanced sonochemistry effect, cavitation, turbulence and shear stress which increased essential oil quantity and the rate of extraction process. The important issues that needed to be considered in optimizing ultrasonic extraction process was over turbulence which could cause agitation and overhigh temperature which potentially could damage the active biochemical compounds inside butterlfy pea flower as a natural susbtance.

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