Papers by Keyword: Fluidized Bed Reactor

Abstract: In this study, dolomite was heated under CO₂ and N₂ gases using fluidized bed reactor from 85 °C to 835 °C. Dolomite under N₂ atmosphere did not show any significant changes on its crystallite size, suggesting there is no significant chemical reaction. On the other hand, dolomite under CO₂ atmosphere shows no significant changes on its crystallite size until it reaches high temperature (> 800 °C) where MgO started to be observed in X- ray diffraction. This shows that few chemical reactions started to happen in this reaction condition.

Abstract: The high organic material contained in wastewater released into the environment asresults of various sources of human activities, such as phosphorus, can cause eutrophication. Thestruvite crystallization in an aerated fluidized bed reactor is one of the methods which able toimprove the efficiency of phosphorus removal. In this study, a mixture of synthetic wastewaters andthe MgCl2 solution was treated in a fluidized bed reactor equipped with aeration to produce thestruvite which can be utilized as a slow release fertilizer. Subsequently, the effect of aeration atdifference influent flow rate was investigated to correlate with the changing of phosphorusconcentration in the reactor effluent. The experiments were conducted for 240 minutes with thevariation of aeration are 0.5 L/min to 1.5 L/min; variation of influent flow rate of syntheticwastewater is 150 ml/min to 350 ml/min, with a constant influent flow rate of MgCl2 solution is 50ml/min. These solutions were maintained at the condition of pH 9. The results showed that theoptimal efficiency of phosphor removal which accounted for 82.5% occurred when the aeration rateof 1.5 L/min in the influent flow rate of 150 ml/min. From these findings, it is revealed that theefficiency of P removal in wastewater is obtained by a crystallization process which utilizing anaerated fluidized bed reactor and by increasing the aeration rate and the reactants contact time.

Abstract: In Malaysia, approximately 7 million tonne/year of rubber wood waste and 5 million tonne/year of acacia wood waste were generated in 2011. These hardwood residues could be utilized to produce biofuel through pyrolysis process. The aims of the paper are to study the fluidized bed pyrolysis system, determine the properties of pyrolytic bio-oil, and highlight the effect of biomass type, size and pyrolysis temperature on pyrolytic products distribution.

Abstract: Bio-oil production from pyrolysis of 0.15-0.5 mm and 1-2 mm palm kernel shell (PKS) has been investigated in a fluidized bed reactor under the nitrogen gas flow rate of 25 L(NTP)/min, with reactor temperature of 450^°C. The pyrolysis unit has six successive condensers. Thus, six fractions of bio-oil samples were acquired from the six condensers. The calorific value, water content, ash content, and element content of each bio-oil samples were determined. The bio-oil yield from palm kernel shell with the size of 0.15-0.5 mm and 1-2 mm were 20 % and 26 %, respectively. The highest calorific value among the six bio-oil samples was 25.1 MJ/kg which was drawn from the forth condenser from pyrolysis of 0.15-0.5 mm of palm kernel shell. The incondensable gas was a mixture of hydrogen, methane, carbon dioxide and ethane.

Abstract: TiO₂/active carbon (AC) photo catalysts are prepared by sol-gel method. We have designed a fluidized bed reactor to decontaminate the formaldehyde. In our experiment, active carbon and TiO₂/AC are used as the air purification materials in the reactor. Flat aluminum sheets and electric field are introduced into the reactor. Our result shows that TiO₂/AC materials have high removal rate, and it can reach 80%. When we add flat sheets and stable electric field, the removal rate reach over 90%.

Abstract: One of the most effective methods for the protection of ferrous substrates from corrosion is zinc hot-dip galvanizing. Although this method has many advantages, it is characterized by a very negative effect on the environment. In the present work Zn coatings were formed with thermal spraying, pack cementation and fluidized bed reactor, which are friendlier to the environment. Their microstructure was characterized with X-ray diffraction and scanning electron microscopy, while their corrosion performance was estimated with exposure in a salt spray chamber. From this investigation it was deduced that CVD coatings are composed by two layers referring to Γ-Fe11Zn40 and δ-FeZn10 phase of the Fe-Zn phase diagram. By contrast the thermal coatings are very porous and composed by pure Zn. However, the corrosion performance of all coatings is similar. This conclusion is very important because it verifies that hot-dip galvanizing could be replaced by the other coating methods.

Abstract: An overview is presented of a multi-year research effort on developing high-rate fluidized-bed bioprocesses for ferric sulfate production to be used as a unit process in various hydrometallurgical applications including indirect tank leaching of ore concentrates, regeneration of heap leach liquors and control of iron containing acidic mine wastewater. Iron oxidation rates of over 26 kg m-3 h-1 were achieved at hydraulic retention times of less than 1 h at 37 °C. Oxygen supply became the rate-limiting factor even with 99.5% dioxygen aeration. Fe2+ oxidation proceeded at pH below 1 even in the presence of 60 g Fe3+ L-1 allowing the regeneration of concentrated ferric sulphate solutions required in indirect tank leaching of sulfidic ore concentrate applications. Of several tested FBR carrier materials activated carbon was the most suitable based on its availability, long-term durability and the achieved high iron oxidation rates. Jarosite precipitates accumulating to the top of the inert carrier materials played an important role in the FBR biomass retainment. For regeneration of synthetic and actual sulfidic ore heap leaching liquors, a gravity settler was installed in the recycle line of the FBR. The system produced iron precipitates with good settling characteristics and settling tank effluent with low turbidity and suspended solids concentrations. These results revealed the potential of FBR process in both heap leach liquor regeneration and controlling the iron containing waste streams. The PCR-DGGE-partial seguencing of the 16S rRNA gene protocol revealed that the FBR culture at 25-37 °C remained dominated by Leptospirillum ferriphilum over a range of operational conditions studied over the years. A modeling approach for managing Fe3+ production by FBR in combination with heap leaching was based on an artificial neural network-back propagation algorithm (ANN-HEAP) and resulted in excellent match between the measured and the predicted concentrations. High-rate fluidized-bed iron oxidation is amenable to regeneration of tank and heap leaching solutions as well as controlling iron containing waste streams.

Abstract: Pyrolysis kinetics of a pine nut shell in a thermo gravimetric analyzer (TGA) and the combustion and steam gasification kinetics of a pine nut shell’s chars in a thermobalance reactor were determined. Also, the steam gasification characteristics of the pine nut shell were determined in a fluidized bed reactor. The maximum pyrolysis reaction rate is obtained at 360oC from the TGA and DTG studies. The activation energy and the pre-exponential factor of the char were determined from the Arrhenius plot based on the shrinking core model. The effects of the reaction temperature (350oC - 950oC) and the O2 partial pressure on the combustion kinetics and that of the steam partial pressure (0.4 - 0.8atm) on the gasification kinetics were determined in a thermobalance reactor. In the combustion reaction, the activation energies and the pre-exponential factors are found to be 21.7 kcal mol-1 at 61.9 s-1atm-1 and 2.36 kcal/mol at 0.0029 s-1atm-1 in the reaction control and the pore-diffusion control regimes, respectively. The reaction order is found to be 1.0 with respect to the O2 partial pressure at 750oC. In the steam gasification reaction, the activation energy and the pre-exponential factor are found to be 16.9 kcal mol-1 at 0.0076s-1atm-1 and 2.67 kcal mol-1 at 0.00036s-1atm-1 in the reaction control and the pore-diffusion control regimes, respectively. The reaction order is found to be 0.77 with respect to the H2O partial pressure at 750oC. The effects of the gas velocity (2Umf - 4Umf), reaction temperature (700oC - 850oC), steam/carbon ratio (0.56 - 1.12) and O2/C ratio (0.16 - 0.32) on the gas composition, gas yield, cold gas efficiency and the calorific value of the product gas were determined in a fluidized bed reactor (10 cm-i.d. × 1.6m-high) with the feeding rate of the pine nut shell of 1 - 3 kg hr-1. The carbon conversion, calorific value, cold gas efficiency and the total product gas yield increased with an increasing temperature. The hydrogen concentration increases with an increasing reaction temperature and the gas velocity and steam/carbon ratio as well as the hydrogen concentration decreases with an increasing O2/C ratio in the fluidized bed reactor.