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This study aimed to investigate the effect of extraction and spray drying temperatures on the yield of bioactive materials during the production of dragon fruit skin extract powder as a natural food colorant. Extraction temperature was varied between 25 and 48 °C, and spray drying was conducted at 140, 170, and 190 °C. Moreover, the effects of spray drying aids were also evaluated. At extraction temperatures below 50 °C, higher temperatures resulted in a higher yield of bioactive materials and a significant increase in antioxidant activity. Regarding spray drying, the use of higher air inlet temperatures resulted in a peaking trend of yield from spray drying. However, employing high air inlet temperatures (above 170 °C) for spray drying may result in a decrease in the recoveries of bioactive materials due to the higher degradation rates. Finally, the addition of maltodextrin as a carrier agent in spray drying could enhance the powder yield.

Biogas is a cost-effective, efficient, environmentally friendly, and renewable alternative energy source. While biogas contains CH4, it also contains impurities in the form of 27–45% CO2 gas. Therefore, it is necessary to purify biogas by removing CO2 gas as it can reduce the calorific value of CH4, the main component of biogas. The process of methane purification can be achieved through adsorption. Bottom ash, derived from palm oil mill waste, shows great potential for methane purification by effectively adsorbing CO2. This research simulated the methane purification process using the computational fluid dynamics (CFD) method with the student version of the ANSYS R20 software. The study utilized an adsorbent made from bottom ash obtained from palm oil mill waste. The main objective was to investigate the performance of bottom ash as an adsorbent for removing CO2 gas in a continuous gas flow within an adsorption column. The study involved varying the column bed height (4 cm, 8 cm, 12 cm) and gas flow rate (10 L/min, 15 L/min, 20 L/min). The results showed that the highest efficiency in removing CO2 gas was 84.53% with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest efficiency was 47.87% with a bed height of 4 cm and a flow rate of 20 L/min. Furthermore, the highest adsorption capacity for CO2 gas was 1.64 mg/g with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest capacity was 0.93 mg/g with a bed height of 4 cm and a flow rate of 20 L/min. The linearization of adsorption isotherm data indicated that the CO2 gas adsorption process using bottom ash adsorbent followed the Langmuir model.

Long-term exposure to pollution from particulate matter in palm oil mills can result in chronic respiratory diseases, cardiovascular diseases and mortality. Particulate matter with a size of less than 2.5 μm (PM2.5) has a greater impact than one with a size of 10 μm. The current PM cleaning equipment in palm oil mills consists of cyclones that are incapable of optimally filtering PM2.5. For this reason, it is necessary to design cyclone applications for fine particle separation in palm oil mills. Normal cyclones are incapable of segregating particles smaller than 2.5 μm. This study's objective was to design a cyclone with a filter on the vortex detector. These cyclones are utilized in PM2.5 fine particle filtration systems. Using computational fluid dynamics, cyclone performance is analyzed in terms of removal efficiency and pressure decrease. The research was conducted utilizing the Reynolds tress model with varying inlet velocities of 10, 15, 20, 25 and 30 meters per second. The filter is composed of boiler bottom ash refuse from palm oil mills; 0.310 meters is the height of the filter bed inserted in the vortex finder. The obtained results demonstrated that the PM2.5 removal efficiency reached 98%, while the pressure decrease was only 93 Pa greater than that of conventional cyclones. Thereby, cyclone designs with bottom ash filters can be used to filter fine particulate matter, particularly particles smaller than 2.5 μm.

This research aimed to analyze the change in chemical composition of the betung bamboo (Dendrocalamus asper) strands after alkali immersion treatment under various immersion times. The bamboo culms were converted into strands with the target length, width, and thickness of 70, 25, and 0.5 mm, respectively. Strands were alkali immersion-treated with 1% NaOH solution for 1, 2, and 3 h. Preparation of powder for chemical component analysis refers to the Technical Association of the Pulp and Paper Industry (TAPPI) standard T 264 cm-07 regarding the preparation of wood test samples for chemical analysis. Structural and non-structural bamboo strand chemical components such as holocellulose, alpha-cellulose, hemicellulose, klason lignin, and extractives were analyzed. The results showed that alkali immersion treatment decreased the hemicellulose content from 21.55% before treatment to 20.30% after 3 h immersion. Thus, it changed the holocellulose and alpha-cellulose composition. Alkali immersion treatment also changed the extractive substances dissolved in cold water, hot water, 1% NaOH, and ethanol-benzene solution. The decrease in hemicellulose, molecular weight lignin, and extractive substances would be beneficial for bamboo-oriented strand board manufacture to improve strand adhesion, dimensional stability, mechanical properties, and durability against biological agents attack. Keywords: alkali immersion times, alkali immersion treatment, bamboo, chemical components, pre-treatment

Post-treatment of bamboo-oriented strand board (BOSB) through thermal modification can be an alternative to improve BOSB quality. This study aimed to analyze the effect of post-thermal treatment duration on the physical and mechanical properties of BOSB. Three-layers BOSB with a target density of 0.7 g/cm3 was made with the core layer perpendicular to the surface and bonded with 8% phenol-formaldehyde resin. The BOSB produced was then thermally-modified at 160°C for 1, 2, and 3 h. The physical and mechanical properties of BOSB were determined based on JIS A 5908-2003 standard. The results showed that the physical properties of the thermally-modified BOSB increased while the mechanical properties decreased compared to the untreated BOSB. The moisture content (MC), water absorption (WA), and thickness swelling (TS) of BOSB decreased with the increase in post-thermal treatment duration. The decrease in MC, WA, and TS of the thermally-modified BOSB reached 38.60%, 11.92%, and 33.26%, respectively. In addition, the decrease in modulus of elasticity (MOE), modulus of rupture (MOR), and internal bonding of the thermally-modified BOSB reached 19.18%, 23.15%, and 53.51%, respectively. The results showed that TS, MOE, and MOR of the thermally-modified BOSB still could meet the 0437.0 standards for commercial OSB (Grade O-1). Keywords: bamboo-oriented strand board, Dendrocalamus asper, physical and mechanical properties, post-thermal treatment, treatment duration

A study of energy optimization derived from simulation software has been done for the high-intensity energy of an Electric Arc Furnace (EAF), hot metal charging within the cooler duct dedusting system. The present work aims to develop a dynamic model of the EAF operation based on mass and energy balances integrated with simulation of the dedusting system with hot metal charging system using MATLAB® and Computational Fluid Dynamics (CFD). The effect of various percentages of hot metal charging on EAF performance and the dedusting system was simulated and validated from the real EAF data plant from one of the steel manufacturer companies in Indonesia. Three cases for the EAF with various hot metal (HM), sponge iron, and scrap iron charging compositions and four cases for the EAF with post-combustion CO have been developed. Careful observation shows that the electric arc power consumption can be reduced down to 72.9 MWh from 87.4 MWh (ca. 16% more efficient) while at the same time increasing the HM charging temperature at the endpoint of the duct dedusting system up to 900°C from 540°C (app. 65% higher). Additionally, advanced simulation of an EAF with post-combustion CO shows that power consumption can be decreased to 59.9 MWh (ca. 30% more efficient).

Agricultural activity relies on soil as their growth media. Besides agricultural activity, other living species also needs soil as their ecosystem. However, the biodiversity and environmental factor are often neglected in agricultural activity. Therefore, the investigation of environmental and biodiversity changes is important. In this study, the environmental parameter and biodiversity changes was investigated in area after land clearing activity. The pH was increased from in 3 times measurement. Besides, the soil temperature and air temperature was also increased in 3 times measurement between pre- and post-treatment. The soil temperature ranges from 26.2 oC to 33.2 oC in pre-treatment and 27.6 oC to 31.8 oC in post-treatment. The air temperature was observed ranges from 27.96 oC to 34.3 oC in pre-treatment and 28.36 oC to 34.56 oC in post-treatment. Measurement of RH was resulted ranges from 61.2% to 75.4% in pre-treatment and 61.4% to 74.8% in pre-treatment. The land is proposed become paddy field for next step land processing. As result, the diversity index was decreased in pre- and post-treatment. The Shannon diversity index was decreased from 0.81 to 0.72. Similarly, the Simpson diversity index was also decreased from 1.94 to 1.77. Meanwhile, the evenness index was increased from 0.58 to 0.65. These results suggested for farmer to process the land as soon as possible after land clearing process, if they want to form paddy field from pasture land. Abstrak Kegiatan pertanian bergantung pada tanah sebagai media tumbuh suatu tanaman. Selain kegiatan pertanian, organisme hidup lain juga bergantung terhadap tanah sebagai ekosistem. Namun, seringkali biodiversitas dan faktor lingkungan diabaikan dalam kegiatan pertanian. Oleh karenanya, indentifikasi perubahan lingkungan dan biodiversitas sanget perlu dilakukan. Dalam penelitian ini, perubahan parameter lingkungan dan biodiversitas diamati sebelum dan sesudah aktivitas land clearing. Hasil pengamatan menunjukkan, pH tanah, suhu tanah dan suhu lingkungan meningkat dalam 3 kali pengukuran dari sebelum ke sesudah aktivitas land clearing. Suhu tanah berkisar 26.2 oC-33.2 oC pada sebelum kegiatan land clearing dan 27.6 oC-31.8 oC setelah aktivitas land clearing. Suhu lingkungan ditemukan berkisar 27.96 oC-34.3 oC pada kegiatan sebelum land clearing dan 28.36 oC-34.56 oC setelah kegiatan land clearing. Hasil pengukuran RH lingkungan ditemukan berkisar 61.2%-75.4% pada kegiatan sebelum land clearing dan 61.4%-74.8% setelah kegiatan land clearing. Sementara itu, index diversitas ditemukan menurun setelah aktivitas land clearing. Nilai Shannon diversity index ditemukan menurun setelah aktivitas land clearing dari 0.81-0.72. Pola serupa ditemukan pada nilai Simpson diversity index, dimana terjadi penurunan dari 1.94 menjadi 1.77. Nilai evenness index meningkat dari 0.58 menjadi 0.65. Berdasarkan hasil tersebut dapat disarankan ke petani untuk segera mengolah lahan tersebut setelah kegiatan land clearing untuk menghindari terjadinya pertumbuhan kembali vegetasi, serta perubahan parameter lingkungan dan biodiversitas.

The alkyd resin industry currently needs environmentally friendly raw materials, which emphasized the aspect of sustainability. Alkyd resin is a polymer product with oil as raw material which is widely used in the paint, coating, and other industries. The abundant demand for alkyd resin has led to a diversification of the raw material for alkyd resin from vegetable oils. The advantages of vegetable oil include being a renewable energy source for industry, sustainability, biodegradability, and being environmentally friendly as important considerations for the industry in recent times. This paper examines alkyd resins derived from several vegetable oils that are environmentally friendly. Alkyd resin is prepared by alcoholysis and esterification. Based on several studies of alkyd resins, there have been many modifications to the raw materials, technology, and catalysts used which can refer to an environmentally friendly and affordable industry. Keywords: alkyd resin; biodegradability; environmentally friendly; sustainability; vegetable oil A B S T R A K Industri polimer pada masa ini membutuhkan bahan baku yang ramah lingkungan, yang menekankan pada keberlanjutan. Alkid resin adalah salah satu produk berbasis minyak yang banyak digunakan dalam industri cat, coating, dan industri lainnya. Keberlanjutan, biodegradabilitas, dan keramahan terhadap lingkungan menjadi pertimbangan signifikan bagi industri berbasis minyak nabati dalam beberapa waktu terakhir. Di dalam naskah ini, diulas beberapa minyak nabati yang digunakan untuk memproduksi alkid resin dengan cara alkoholisis dan esterifikasi. Berdasarkan berbagai studi yang telah dilakukan, masih terdapat modifikasi dari sisi material, teknologi dan katalis agar tercipta industri yang ramah lingkungan. Kata kunci: alkid resin; biodegradabilitas; keberlanjutan; minyak nabati; ramah lingkungan

Mercury is a liquid metal that has properties such as toxic, persistent, bioaccumulating, and its vapor can spread around sources so that it is harmful to humans. Despite having dangerous properties, mercury is found in some goods, products, and also waste. Mercury is indicated to be used in several industries, such as artisanal and small-scale gold mining and coal-fired steam power plants. Based on health and environmental considerations, mercury must ultimately be removed from the eco cycle. Mercury storage systems in the long term must be solved so that sustainable development for future generations can be achieved. Currently, there is still no mercury storage system in Indonesia with a good standard design, so the conceptual design study of the mercury elemental storage system is important. In this paper, the storage tanks with a mercury capacity of 35 kilograms, one tonne, and two tonnes were designed to meet mercury storage standards. Several design criteria were used as model development, such as storage capacity, height level, safety factor material, storage temperature, tank life span, and symbols and label. The design results presented in this paper are dimension and engineering drawing of the storage tanks and attributes like spill tray, pallet, and rack. Keywords: environment; hazardous and toxic material; Indonesia; mercury; storage tanks

Xylitol is a low-calorie, natural sweetener which has similar sweetness properties to sucrose. Xylitol can be produced from the hemicellulose hydrolysate of Oil Palm Empty Fruit Bunches (OPEFB). Several steps required for this process, including pretreatment, the hydrolysis of xylan to xylose and the reduction of xylose to xylitol. In a commercial market, xylitol is commonly found in the form of powder in order to maintain its distribution stability and practicality. The spray drying method is a drying method that is mostly used in dry or powder products manufacturing industry. This research aims to investigate the effect of spray drying and to determine proper inlet temperature and maltodextrin concentration on xylitol powder characteristics that are similar to the quality of commercially produced xylitol. Randomized Group Design Method is a data processing method used in this research which consisted of two factors: inlet temperature (160 oC and 180 oC) and maltodextrin concentrations (20%, 25%, and 30%). Based on the result of the research, the inlet temperature significantly affected the water content, solubility, hygroscopic levels and calorie content. Results also showed that maltodextrin concentration had a significant effect on the hygroscopic levels, water content and calorie content. Xylitol powder similar to the commercially produced xylitol was obtained from the inlet temperature of 160 oC and 20% of maltodextrin, with the water content of 5.17%, hygroscopic levels of 8.55%, solubility of 99.346%, calorie content of 2.71 cal/g and xylitol content of 0.034 g/L.

Human and industrial activities produce air pollutants that can cause a decline in air quality. In urban areas, transportation activities are the main source of air pollution. One of the emitted air pollutants produced by transportation is carbon monoxide (CO). The understanding of CO concentration is crucial since its overabundance beyond a certain limit will have a negative impact on human health and the environment. In this study, the support vector regression (SVR) method was used to predict CO concentration. The purpose of this study was to predict the hourly CO concentration in the Ujung Berung district, Bandung City, West Java, Indonesia with optimal prediction accuracy. An experiment was carried out by modeling the CO concentration with varying kernel parameter values to obtain accurate prediction results. The suitability of the values between error (ɛ), a trade-off constant (C), and variation mismatch (γ) is vital to obtain optimal prediction results. The results showed that the best prediction accuracy value was 97.68% with kernel parameter values ɛ = 0.02, γ = 30, and C = 0.006. These results may lead to proper decision making on environmental issues and can improve air pollution control strategies.

Indonesia has an abundance of biomass from agricultural, plantation, and domestic waste products. Biomass can be converted into fuels and chemicals that are environmentally friendly. Empty fruit bunches (EFB) are biomass from abundant palm oil processing. Pyrolysis was a thermal process with free oxygen at temperatures between 400-600°C. Generally, pyrolysis was carried out under fast pyrolysis to produce a product that leads to bio-crude oil. One of the main components of bio-crude oil was phenol, which had been produced from further processing of crude oil. With the limitations of crude oil, the production of phenol from biomass pyrolysis was an option for the future, especially for fuels and fuel additives. Thus, it is necessary to investigate the effect of heating rate, temperature pyrolysis, and holding time on pyrolysis products including phenols in bio-crude oil. Slow pyrolysis of EFB was performed at various parameters, including temperatures (400, 450, and 500°C) and holding time (5, 10, and 15 min). Slow pyrolysis of oil palm EFB with variations in temperature and holding time has been carried out by producing liquid between (40 - 42 %weight), gas (19 – 21 % weight), and solid products (38 – 39 % weight). Biocrude oil liquid product showed the highest yield compared to biochar and bio pyrolysis gas. Temperature plays an important role in controlling the production of bio-crude oil as a liquid product, including a component in bio-crude oil. Phenol recovery was more affected by temperature instead of holding time.

Dragon fruit is one of the tropical fruits can be grown in Indonesia. The skin of dragon fruit, which is accounted for 30-35% of the whole fruit usually thrown away as waste. This study aims to produce a bioactive extract from extraction of dragon fruit skin that is rich in phenolic and pigment compounds then it used as food additives. The variation that was used in this study includes the application of drying as pre-treatment of dragon fruit skin and the extraction methods (maceration and Soxhlet extraction). The obtained extracts were evaluated for the amount of total phenolic compounds and pigments (anthocyanin and betacyanin). Drying of dragon fruit skin was found to yield lower amounts of bioactive materials, which may occur due to the thermal degradation even though a low drying temperature was used. In addition, the maceration method was found to give a higher amount of bioactive materials compared with the Soxhlet method. The extraction with the highest yield of bioactive materials was obtained by the use of fresh dragon fruit skin and maceration for 240 minutes, which gave amounts of anthocyanin, betacyanin, and total phenolic compounds of 0.08, 0.04, dan 0.35 mg/g fresh dragon fruit skin, respectively.

Geopolymer as a Portland cement substitute had been synthesized from alkaline activation of co-combustion residuals of bamboo and kaolin. Types of used alkaline activators were NaOH solution, KOH solution, a mixture of NaOH solution-water glass, and a mixture of KOH solution-water glass. Geopolymer with NaOH solution as activator had a compressive strength which was higher compared to geopolymer with KOH solution as an activator. However, geopolymer with NaOH solution-water glass as activator had a compressive strength which was lower compared to geopolymer with KOH solution-water glass as activator either at room temperature curing or at a curing temperature of 60 °C. The use of water glass with NaOH or KOH solution as activator could increase the compressive strength of geopolymer and yielded geopolymer having more dense and more homogeneous microstructure seen from SEM images. XRD patterns revealed the presence of sodium aluminosilicate hydrate in geopolymer with NaOH solution and NaOH solution-water glass as activators, and potassium aluminosilicate hydrate in geopolymer with KOH solution and KOH solution-water glass as activators. Furthermore, FTIR spectra indicated asymmetrical vibration of Si(Al)-O at around 1008 cm-1 related to geopolymer product.

Tujuan umum dari penelitian ini adalah untuk pencapaian ketahanan pangan Indonesia melalui pembangunan industri hilir berbahan baku tepung nangka. Tujuan khususnya adalah untuk melakukan kajian mengenai produksi tepung nangka menggunakan alat pengering dengan sistem pengering gabungan antara perpindahan panas tidak langsung dan kondisi vakum. Penelitian ini terbagi kedalam 3 tahap. Tahap pertama adalah merancang alat pengering, uji performa alat pengering, dan penentuan kondisi optimum untuk produksi tepung nangka. Tahap kedua adalah pengujian umur simpan tepung nangka. Tahap ketiga adalah uji kegunaan tepung nangka yang dihasilkan. Hasil penelitian tahap pertama menunjukan bahwa alat pengering hasil perancangan memiliki performa yang baik. Hal ini ditunjukan dengan nilai humiditi dari ruang pengering sebesar 0,0186 kg H2O / kg udara kering dan tekanan yang stabil selama proses pengeringan yaitu sebesar -61,5 cmHg.

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.

Bamboo has been widely used in Indonesia for construction, handicrafts, furniture and other uses. However, the use of bamboo as a biomass for renewable energy source has not been extensively explored. This paper describes the thermal and ash characterization of three bamboo species found in Indonesia, i.e. Gigantochloa apus, Gigantochloa levis and Gigantochloa atroviolacea. Characterization of bamboo properties as a solid fuel includes proximate and ultimate analyses, calorific value measurement and thermogravimetric analysis. Ash characterization includes oxide composition analysis and phase analysis by X-Ray diffraction. The selected bamboo species have calorific value comparable with wood with low nitrogen and sulphur contents, indicating that they can be used as renewable energy sources. Bamboo ash contains high silicon so that bamboo ash has potential to be used further as building materials or engineering purposes. Ash composition analysis also indicates high alkali that can cause ash sintering and slag formation in combustion process. This implies that the combustion of bamboo requires the use of additives to reduce the risk of ash sintering and slag formation. Article History: Received May 15, 2016; Received in revised form July 2nd, 2016; Accepted July 14th, 2016; Available online How to Cite This Article: Purbasari, A., Samadhi, T.W. & Bindar, Y. (2016) Thermal and Ash Characterization of Indonesian Bamboo and its Potential for Solid Fuel and Waste Valorization. Int. Journal of Renewable Energy Development, 5(2), 95-100. http://dx.doi.org/10.14710/ijred.5.2.96-100

The increasing concentration of CO2 and other greenhouse gasses (GHGs) in the atmosphere warms up the earth's surface and causes drastic changes to the climate. Therefore, reducing energy consumption in order to reduce GHGs emission from the manufactures become urgent, especially in developing new industries such as Slow Release Fertilizer (SRF) urea plant. In this work, mixing in an orbiting screw mixer designed for solid-solid mixing was investigated. Mixing was carried out using urea powder and natural zeolite powder by varying three particle sizes i.e. groups of >50 mesh, >60 mesh and >80 mesh. Mixing process was conducted to examine the influence of orbital and rotation speeds combined with air injection, as well as the particle size of urea-natural zeolite to the specific energy consumption. Achieving a good homogeneity of mixture with a shorter mixing time, thus, power and energy consumption, was one goal of this work. The power consumption was calculated from measured torque of orbital and screw obtained by computerized record. Specific energy consumption was calculated by total power with time tied the homogeneity of the mixture for each particle size group. Experimental results showed that the higher of the orbital and rotation speed, the higher energy consumption. It can be seen that power consumption was dominated by rotation motion of the screw. Smaller particle size required higher power for mixing process due to their cohesiveness. Mixing process used a modified orbiting screw mixer with air injection showed lower power consumption for each particle size group compared with that of no air injection. This paper also developed a derivation of the power equation model of mixing in the orbiting screw mixer. The influence of speed of mixer in an orbiting screw mixer on the power consumption can be expressed by the Power Number.

Makalah ini mengkaji tentang pemodelan dan simulasi oksidasi katalitik metana menggunakan reverse flow reactor (RFR). Pokok bahasan tertuju pada pengembangan prosedur pengambilan panas dalam periode start-up untuk umpan dengan konsentrasi tetap, yaitu 1%-v metana dan umpan dengan konsentrasi berfluktuasi, yaitu pada rentang 0,1-1%-v metana, yang mengikuti fungsi gelombang persegi. Hasil simulasi menunjukkan pengambilan panas dapat dilakukan selama start-up baik untuk konsentrasi tetap maupun konsentrasi berfluktuasi tanpa menyebabkan RFR padam. Pengambilan panas pada switching time (ST) yang cepat memberikan beberapa keuntungan dibandingkan pada ST yang lama, yaitu lebih banyak panas yang dapat diekstrak dan lebih besar penurunan temperaturnya, sehingga aman bagi katalis dan reaktor.

The present study is an attempt to introduce the method for optimizing the geometry of the unit process. The comprehensive unit process performances are generated by a CFD engine. The CFD engine can simulate the unit process performances at what ever conditions. Both design geometry and operating variables weree used on the CFD simulation. The burden on a simplified process was taken out from CFD simulation. A complex geometry of a unit process is represented by a secondary reformer. A secondary reformer has a conical volume as a space to undergo the combustion reaction before entering the catalyst bed. This complexity is added by the boundary of the porous solid surface as the top surface of catalyst bed. The spread angle affect the flow pattern in side the conical volume having a porous solid surface as a base. The spread angle above 65o results the disappearing of the recirculation flow. The inlet distance from the porous solid surface also can exhibit different characteristics of recirculation flow. The closer the distance to the porous solid surface, the stronger the recirculation is. The inlet velocity values have no significant effect on the flow pattern. The introduction of a solid volume inside the geometry creates the distortion of the flow pattern. In the application, the inserted solid volume is equivalent to a burner. It means that the use of the burner inherently produces some problems of the flow distribution

In a packed bed catalytic reactor, the fluid flow phenomena are very complicated because the fluid and solid particle interactions dissipate the energy. The governing equations were developed in the forms of specific models. The shear factor model was introduced in the momentum equation for covering the effect of flow and solid interactions in porous media. A two dimensional numerical solution for this kind of flow has been constructed using the finite volume method. The porous media porosity was treated as non-uniform distribution in the radial direction. Experimentally, the axial velocity profiles produce the trend of having global maximum and minimum peaks at distance very close to the wall. This trend is also accurately picked up by the numerical result. A more comprehensive shear factor formulation results a better velocity prediction than other correlations do. Our derivation on the presence of porous media leads to an additional viscosity term. The effect of this additional viscosity term was investigated numerically. It is found that the additional viscosity term improves the velocity prediction for the case of higher ratio between tube and particle diameters.

We presented the mathematical model in the iron reactor. The model was limited to Isobaric Zone and Cooling Zone termed as IZ and CZ, respectively. The simulation was done by adapting the heat and mass transfer equations. The main purpose of this paper is to estimate the temperature increasing effect of reduced-iron on sponge-iron quality. The calculations are solved using Finite Element Method (FEM). The results showed that the temperature and concentration values from the simulation have high similarity to the reference data with Root-Mean-Square Error (RMSE) about 0.7. The formation of total-carbon in the both zones decreased metallization degree until 1.72%. The increase in reduced-iron temperature higher than 1200 K produces total-carbon higher than 3%. Thus the increase in reduced-iron temperature more than 1200 K is not recommended because it can decrease metallization degree.