Fuel Processing Technology (v.122, #C)
Editorial Board (IFC).
Experimental characterization of a high sulfur Hungarian brown coal for its potential industrial applications by Alberto Pettinau; Zsolt Dobó; Zoltán Köntös; Andor Zsemberi (1-11).
Differently from the conventional combustion and entrained flow gasification technologies, fixed-bed up-draft gasification process tested in pilot scale appears very suitable for the “multipurpose transformation” of Hungarian low-rank and high sulfur brown coal (for the production of electrical energy, heat and eventually gaseous or liquid fuels). This paper presents the positive results of the wide-range analysis (led jointly by Sotacarbo in Italy and by Ormosszén in Hungary) on the possibility to use the Hungarian coal from the North-East basins for energy purposes.At this stage, there is no scientific literature on this subject (the energetic use of this fuel, which is very complex in conventional power generation plants), whereas there are several studies on the geological properties of the Hungarian brown coal and on the energetic exploitation of the Mecsek basin's high-rank coal.In addition to the conventional characterization (proximate, ultimate and thermal analyses), a series of bench-scale experimental tests were carried out to preliminary assess the combustion performance of Hungarian brown coal and to set a pilot-scale experimentation in the Sotacarbo gasification pilot plant. As results from the experimental tests, the air-blown up-draft gasification of about 11 kg/h of Hungarian brown coal allows to produce about 24–25 kg/h of raw syngas, characterized by a lower heating value of 3.55 MJ/kg.The high sulfur content in primary fuel is one of the main problems when that coal is used. As a matter of fact, conventional cold gas desulfurization processes are typically not sufficient for an efficient syngas desulfurization. But a very high H2S and COS removal efficiency has been experimentally obtained treating syngas with a zinc oxide-based hot gas desulfurization system. This process allowed to obtain a final H2S and COS global concentration lower than 20 ppm (by volume), operating at about 400 °C.
Keywords: Coal gasification; Brown coal; High sulfur; Pilot platform; Syngas treatment;
Catalytic cracking of heavy naphtha-range hydrocarbons over different zeolites structures by Abdallah A. Al-Shammari; Syed A. Ali; Nabil Al-Yassir; Abdullah M. Aitani; Kehinde E. Ogunronbi; Khalid A. Al-Majnouni; Sulaiman S. Al-Khattaf (12-22).
The effects of textural, structural, morpholgical, and acidic properties of HZSM-5, H-mordenite and (MFI/MOR) composite zeolite on the catalytic cracking of heavy naphtha-range hydrocarbons (dodecane, iso-octane, and ethylbenzene) as well as heavy naphtha were studied. XRD and SEM results revealed the presence of (MFI/MOR) overgrowth composite zeolite upon recrystallization of H-mordenite in the presence of tetrapropylammonium bromide. Significant cracking of dodecane occurred over different zeolites, however, very low cracking of iso-octane was observed over HZSM-5. The conversion of ethylbenzene, iso-octane and dodecane at 400 °C was 69.6, 74.5 and 86.4 wt.%, respectively, over H-mordenite, compared with 69.8, 11.2 and 83.8 wt.%, respectively, over HZSM-5. (MFI/MOR) overgrowth zeolite exhibited an intermediate level of cracking. Catalytic cracking of hydrocarbon mixtures followed similar trends as those for pure model compounds. Catalytic cracking of heavy naphtha was higher over HZSM-5, compared to H-mordenite (94.4 wt.% vs. 76.5 wt.%). The kinetic modeling studies indicated that the rate of hydrocarbon cracking varies with the nature of model compounds and zeolite structure. The apparent activation energies (Ea ) for the three model compounds increased in the following order; HZSM-5 > (MFI/MOR) > H-mordenite, whereas the difference in Ea over various zeolites was much larger for iso-octane and ethylbenzene.
Keywords: Catalytic cracking; Heavy naphtha; H-mordenite; HZSM-5; (MFI/MOR) composite zeolite;
Pd catalyst supported on activated carbon honeycomb monolith for CO oxidation and the application in air purification of vehicular tunnel by Li Wang; Yanhui Zhang; Yang Lou; Yanglong Guo; Guanzhong Lu; Yun Guo (23-29).
Different pretreatments (wet, oxidation and complex pretreatments) were used to modify activated carbon honeycomb monolith, and the role of surface properties of support in CO oxidation over Pd/ACHM catalysts was also investigated. Pretreatment was an efficient way to introduce oxygen groups, especially by complex pretreatment. Oxygen-containing groups increased 1.7 times as much as that of original ACHM, and 86% conversion was obtained at 30 °C and 100% relative humidity on supported Pd catalyst prepared from modified ACHM. Oxygen-containing species on the support not only improved Pd dispersion but also affected Pd states. Compared with Pd dispersion, Pd states played a more important role in CO oxidation. The amount of low-valent Pd species (Pd0, Pd+ 1) on catalyst surface was consistent with CO oxidation activity. The presence of NO caused CO oxidation conversion to decrease by 15% which was attributed to the difference between NO and CO adsorption energy on Pd surfaces confirmed by density functional theory calculation. 90 days' 1000 m3/h pilot experiment results showed that the catalyst exhibited high activity and stability in the presence of moisture and NOx.
Keywords: CO oxidation; Ambient temperature; Monolithic activated carbon; Support pretreatment; Tunnel air purification;
Effect of process conditions on equilibrium, reaction kinetics and mass transfer for triglyceride transesterification to biodiesel: Experimental and modeling based on fatty acid composition by B. Likozar; J. Levec (30-41).
Detailed reaction kinetics of oil transesterification were studied based on mechanism and reaction scheme of individual triglyceride, diglyceride, monoglyceride, glycerol and fatty acid methyl ester containing different combinations of gadoleic, linoleic, linolenic, oleic, palmitic and stearic acids determined by high-performance liquid chromatography. Pre-exponential factors and activation energies were correlated with molecular structure in terms of chain lengths and double bonds by response surface models. The activation energies of forward reactions were 47–61 kJ mol− 1 with backward ones being 31–49 kJ mol− 1, depending on component structure. Mass transfer during initial emulsion phase was acknowledged by determining diffusivities, distribution coefficients, molar volumes, boiling points and viscosities of individual components. Model was validated for a wide range of temperatures, hydrodynamic conditions, dispersed and continuous phase ratios, and methanolysis catalyst concentrations. Rotational speed had the most profound influence on the duration of transport phenomena-limited region spanning the latter to 27 min upon use of 100 rpm. Economics of the process were finally evaluated in terms of alcoholysis cost and price breakdown. Proposed methodology may be usefully applied to transesterification syntheses employing heterogeneous catalysis and enzymes, as well as various renewable resources such as microalgae lipids, waste oils, bioethanol and biobutanol.Display Omitted
Keywords: Biodiesel production process optimization/intensification; Reaction mechanism/kinetics; Mass transfer/diffusion; Renewable energy/fuels;
Fuel properties and rheological behavior of biodiesel from egusi (Colocynthis citrullus L.) seed kernel oil by Solomon O. Giwa; Luqman A. Chuah; Nor M. Adam (42-48).
In this study, egusi (Colocynthis citrullus L.) seed kernel oil has been evaluated as a feedstock for biodiesel production. The transesterification of the crude egusi seed kernel oil (CESKO) via methanol in the presence of sodium methoxide was performed and the resulting egusi oil methyl ester (EOME) was tested for its fatty ester composition, fuel properties and rheological behavior (at 25 °C, 40 °C and 55 °C). The fuel properties of EOME measured met both the ASTM D6751 and EN 14214 biodiesel standards, with the exception of lower oxidative stability. The fatty ester composition and fuel properties of EOME were found comparable to those of conventional biodiesels from soybean, sunflower and safflower oils. The viscosity behavior of EOME and its blends with diesel fuel (at 25 °C, 40 °C and 55 °C) was found to be pseudoplastic and Newtonian in nature and this agrees with those of other biodiesels reported in literature. From this study, the kinematic viscosity of EOME (3.91 mm2/s) was found to be slightly lower than that of most biodiesels (≥ 4.0 mm2/s) reported in literature.
Keywords: Biodiesel; Fuel properties; Egusi kernel oil; Transesterification; Rheology;
Influence of acid treatment on N-doped multi-walled carbon nanotube supports for Fischer–Tropsch performance on cobalt catalyst by Tingjun Fu; Renjie Liu; Jing Lv; Zhenhua Li (49-57).
Nitrogen-doped carbon nanotubes (NCNTs) were acid treated and used as a support for Co catalysts. The effect of acid treatment time on the carbon structure, surface properties and the microstructure of Co catalysts was extensively characterized by BET, XRD, TPR, XPS, TEM and Raman spectroscopy. It was found that acid treatment affected the support structure, the Co reducibility, the Co dispersion and the Fischer–Tropsch (FT) synthesis performance significantly. The graphitization degree, cobalt particle size, cobalt particle location and the number of active sites determined the FT synthesis performance of the Co catalysts.
Keywords: Fischer–Tropsch synthesis; Cobalt catalyst; N-doped CNTs; Acid treatment;
Efficiency of small-scale firewood processing operations in Southern Europe by Marco Manzone; Raffaele Spinelli (58-63).
The study determined the performance of small-scale commercial firewood processing operations under the typical work conditions of Southern Europe. In particular, five units were tested, fed with the same 2.1-m long beech (Fagus sylvatica L.) logs. All machines were tested with sorted and unsorted logs. Productivity varied between 1.1 and 2.1 t h− 1, and cost between 20 and 39 € t− 1. There were significant differences between machines, which may partly be attributed to operator effect. Feeding the machines with sorted logs had a significant effect on the productivity of all machines on test, increasing productivity by 40% and reducing cost by 34%. Fuel use varied between 1.3 and 2.8 l t− 1. The energy balance was always very favorable. The ration between output and input was never smaller than 59 to 1 and peaked at 130 to 1. In other words, processing required about 1% of the energy contained in the firewood — or 1.7% in the worst case. The productivity figures reported in this experiment were much lower than reported for Northern Europe, which seems to confirm the significant effect of regional work conditions – especially different wood species – on firewood processing performance.
Keywords: Biomass; Energy; Productivity; Forestry; Beech;
Pollutant emissions from New European Driving Cycle with ethanol and butanol diesel blends by Octavio Armas; Reyes García-Contreras; Ángel Ramos (64-71).
In this study, regulated gaseous emissions, smoke opacity and particle concentration derived from diesel fuel and two blends with alcohols (10% of ethanol and 16% of butanol) have been studied. A turbocharged, direct injection (DI), diesel engine equipped with common rail, injection system and EGR strategy was tested in test bench with road load simulation (RLS) during the New European Driving Cycle (NEDC). The tests were carried out always measuring upstream of the diesel particle filter (DPF). Results show slight increases in NOx and THC emissions with alcohol blends whereas CO emissions were reduced with these fuels. Particle mass (PM) was estimated from both the smoke opacity and particle size distributions. In both cases, important benefits are observed with alcohol blends.
Keywords: Diesel engine; Ethanol–diesel blends; Butanol–diesel blends; Pollutant emissions; NEDC; Transient operation;
Transesterification of non edible feedstock with lithium incorporated egg shell derived CaO for biodiesel production by Jutika Boro; Lakhya Jyoti Konwar; Dhanapati Deka (72-78).
A series of Li doped egg shell derived CaO is prepared for biodiesel production from nonedible oil feedstock. The catalyst is characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunauer–Emmett–Teller (BET) surface area measurements and their basic strengths were measured by Hammett indicators. Maximum conversion of 94% is observed with 5% of catalyst amount and 2% of Li loading is observed to be optimum for better conversions. Though the catalyst is not reusable its catalytic activity can be improved by activating it at appropriate temperature and reloading it with Li. NMR studies showed that the final product separated after transesterification is biodiesel.Display Omitted
Keywords: Egg shell; Doped catalyst; Biodiesel; Transesterification; Characterization;
Production, characterization and fuel properties of alternative diesel fuel from pyrolysis of waste plastic grocery bags by Brajendra K. Sharma; Bryan R. Moser; Karl E. Vermillion; Kenneth M. Doll; Nandakishore Rajagopalan (79-90).
Pyrolysis of HDPE waste grocery bags followed by distillation resulted in a liquid hydrocarbon mixture with average structure consisting of saturated aliphatic paraffinic hydrogens (96.8%), aliphatic olefinic hydrogens (2.6%) and aromatic hydrogens (0.6%) that corresponded to the boiling range of conventional petroleum diesel fuel (#1 diesel 190–290 °C and #2 diesel 290–340 °C). Characterization of the liquid hydrocarbon mixture was accomplished with gas chromatography–mass spectroscopy, infrared and nuclear magnetic resonance spectroscopies, size exclusion chromatography, and simulated distillation. No oxygenated species such as carboxylic acids, aldehydes, ethers, ketones, or alcohols were detected. Comparison of the fuel properties to the petrodiesel fuel standards ASTM D975 and EN 590 revealed that the synthetic product was within all specifications after addition of antioxidants with the exception of density (802 kg/m3). Notably, the derived cetane number (73.4) and lubricity (198 μm, 60 °C, ASTM D6890) represented significant enhancements over those of conventional petroleum diesel fuel. Other fuel properties included a kinematic viscosity (40 °C) of 2.96 mm2/s, cloud point of 4.7 °C, flash point of 81.5 °C, and energy content of 46.16 MJ/kg. In summary, liquid hydrocarbons with appropriate boiling range produced from pyrolysis of waste plastic appear suitable as blend components for conventional petroleum diesel fuel.Display Omitted
Keywords: Plastic; Pyrolysis; High-density polyethylene; Fuel; Diesel; Biodiesel;
Use of biodiesel in marine fuel formulation: A study of combustion quality by Elisia dos Santos Prucole; Ricardo Rodrigues da Cunha Pinto; Maria Letícia Murta Valle (91-97).
The quality of ignition and combustion of blends of soy biodiesel and marine fuels was evaluated. Faced with the increasing implementation of processes for converting heavier oil fractions, the availability of streams to formulate marine fuels has been reduced. In this context, the use of biodiesel is important to minimize problems caused by the retraction in production of these streams and improve marine fuel quality. Since composition and stability properties are of great importance and influence directly the combustion quality, the composition was determined using the SARA analysis by thin layer chromatography and a flame ionization detector and the mixtures' stability evaluation was made by optical scanning. Using the equipment Fuel Combustion Analyzer, mixtures of marine fuels and soy biodiesel were tested, varying the biodiesel content by volume in the mixture at levels up to 10% v/v. The results show that the addition of biofuel to marine fuels, in the evaluated conditions, does not compromise the combustion quality of the bunker oil and, in some cases, had even increased the estimated cetane number, indicating increased quality of ignition and combustion.
Keywords: Bunker; Combustion; Ignition quality; Biodiesel; Marine fuel;
Catalytic upgrading of coal pyrolysis tar over char-based catalysts by Jiangze Han; Xingdong Wang; Junrong Yue; Shiqiu Gao; Guangwen Xu (98-106).
Catalytic upgrading of coal pyrolysis tar was investigated in a dual-stage reactor over char and metal-impregnated char (Co-char, Ni-char, Cu-char, Zn-char). The catalytic upgrading caused the lower total tar yield and the higher non-condensable gas yield but the fraction of light tar (boiling point < 360 °C) obviously increased to allow slightly higher total yield of light tar. When the catalytic upgrading was at 600 °C over a layer of char having a mass of 20% of the tested coal, the resulting light tar fraction in the tar increased by 25% in comparison with the coal pyrolysis only at 600 °C. Over the metal-impregnated char, which was 5% of the tested coal in mass, good upgrading effect was obtained at 500 °C. The catalytic tar-upgrading activity decreased in an order of Co-char > Ni-char > Cu-char > Zn-char, and over Ni-char the realized light tar yield and its content in the tar increased by 17.2% and 32.7%, respectively. The upgrading effect also lowered the contents of element N and S in the resulting tar by 45.6% and 43.5%, respectively. NH3-TPD clarified that the order in acidity of the char-based catalysts was the same as for the upgrading activity shown above.This figure compares the fraction and yield of light tar (boiling point < 360 °C) obtained from coal pyrolysis under the conditions without (Blank) and with secondary catalytic upgrading over various char-based catalysts. In comparison with the pyrolysis without secondary upgrading, the adoption of the secondary upgrading all evidently increased the light tar fraction, while only the catalysts impregnated with metal species caused obvious increase in the light tar yield. The Ni-char catalyst showed the best upgrading effect, and next to this was the Co-char catalyst. These results demonstrated that the secondary catalytic upgrading greatly improved the tar quality, and this would greatly facilitate the downstream treatment for the tar.Display Omitted
Keywords: Coal pyrolysis; Catalytic upgrading; Tar quality; Char-based catalyst;
Lubricity assessment of gasoline fuels by P. Arkoudeas; D. Karonis; F. Zannikos; E. Lois (107-119).
This paper presents the lubricity measurements of the three commercial gasoline types, unleaded gasoline (95 RON), new super or LRP (96 RON) and super unleaded gasoline (98 RON) and the effects of various physico-chemical properties on lubricity. The results indicate that the nature of the fuel is an important factor for the lubrication properties of each type of gasoline fuel. The potassium content takes an active part in this and the amount that is added to the fuel doesn't seem to affect the final result of CWSD1.4 proportionally. A careful statistical approach to the data identified that, the composition, the sulfur and nitrogen contents, the oxygen content that is mainly contributed from the MTBE content and the viscosity, do affect the lubricity but in a different degree for each type of fuel. This differentiation of the properties' effect on lubricity, reinforces the idea of the complicated wear mechanism that takes place under the specific conditions of the experiments and the important role of the compositional characteristics of the fuel. Oxygen content and MTBE seem to maintain or even increase the wear mechanism. Chlorine was also detected on the metal surface of the specimens after scanning with electron microscopy (SEM).
Keywords: Lubricity; HFRR; Gasoline fuels; Wear mechanisms; Refinery streams; SEM;
Hydroisomerization of n-dodecane on a new kind of bifunctional catalyst: Nickel phosphide supported on SAPO-11 molecular sieve by Shasha Tian; Jixiang Chen (120-128).
A new type of nickel phosphide catalysts supported on SAPO-11 was used for the hydroisomerization of n-dodecane. Their properties were characterized by means of N2-sorption, H2-TPR, XRD, XPS, DRIFTS of adsorbed pyridine, CO chemisorption, and NH3-TPD and H2-TPD. The effects of the Ni/P ratio and the nickel content on catalyst performance were investigated. For comparison, the property and performance of Ni/SAPO-11 were also considered. Compared to Ni/SAPO-11, SAPO-11 supported nickel phosphides had higher isomerization selectivity due to their lower hydrogenolysis activity. As the Ni/P ratio deceased, the n-dodecane conversion decreased, while the isododecane selectivity reached its maximum at the Ni/P ratio of 1. As the nickel content increased, the n-dodecane conversion and isododecane selectivity reached their maximum. In short, a balance between medium strength acid sites and Ni sites was required for obtaining high n-dodecane conversion and isododecane selectivity. Moreover, there was a synergism between the Ni sites and the medium strength acid site. Under suitable conditions, the isododecane yield reached about 65% on Ni2P/SAPO-11 containing 3 wt% Ni.
Keywords: Hydroisomerization; Hydrocracking; n-Dodecane; Nickel phosphide; SAPO-11; Acidity;
An experimental and modeling study of NOx and CO emission behaviors of dimethyl ether (DME) in a boiler furnace by Yinhu Kang; Xiaofeng Lu; Quanhai Wang; Xuanyu Ji; Shanshan Miao; Chen Zong; Guangyu Luo; Hai Liu (129-140).
NOx and CO emission behaviors of dimethyl ether/air premixed flame in a boiler furnace were studied by experimental and modeling approaches in this paper. Five excess air ratios (1.05, 1.15, 1.30, 1.45 and 1.60) and two thermal loads (high load (about 270 kW) and low load (about 130 kW)) were involved to investigate their effects on the emission behaviors. Besides, a chemical reactor network was constructed on the basis of CFD solutions to calculate NO and CO emissions. A detailed chemical mechanism of dimethyl ether combined with the San Diego NOx chemistry which includes thermal, prompt, N 2 O and NO 2 pathways was used. The research indicated that NO in the flame base was formed via a combination of thermal, prompt and N 2 O pathways. The thermal pathway dominated in the high-temperature (above 1800 K) flame zone. NO in intermediate-temperature (1000–1600 K) regions was generated via the NO 2 pathway. Besides, a considerable amount of NO was converted to NO 2 in the low-temperature (below 1000 K) zones. Emission indices of NO and CO both decreased with the increment of excess air ratio. They became rather small if the excess air ratio was maintained above 1.30 and 1.15 respectively. The effect of thermal load on the NO emission index was insignificant. The CO emission index increased considerably under the high load.The measured, CRN-predicted and CFD post-processor predicted emission indices of NO (a) and CO (b) under different operational parameters respectively.Display Omitted
Keywords: Dimethyl ether; Boiler furnace; NO; CO; Emission behaviors;
Activities of Ni-based nano catalysts for CO2–CH4 reforming prepared by polyol process by Muhammad Awais Naeem; Ahmed Sadeq Al-Fatesh; Ahmed Elhag Abasaeed; Anis Hamza Fakeeha (141-152).
Nano nickel catalysts supported over nano sized oxide powders (CeO2, ZrO2 and Al2O3) were prepared by the polyol method in ethylene glycol (EG) medium with polyvinylpyrrolidone (PVP) as a nucleation-protective agent. The activities of the prepared catalysts were evaluated for CO2 reforming of methane in the temperature range 500–800°C. For comparison purpose, another series of Ni based catalysts was prepared by conventional impregnation method. Numerous techniques, such as N2 adsorption–desorption isotherm, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (CO2-TPD), X-ray diffraction (XRD), thermogravimetric analysis (TGA), high resolution transmission electron microscopy (HRTEM), and pulse chemisorption were applied for characterization of fresh and spent catalysts. The results of catalyst testing and characterization revealed that the catalysts synthesized by polyol method have superior catalytic performance (activity and stability) than those prepared by impregnation method. The better performance of polyol catalysts could be attributed to stronger metal to support interaction and presence of evenly distributed nano nickel particles in these catalysts; since strong metal to support interaction resists sintering and small nickel crystallite size hinders coking.Display Omitted
Keywords: CO2/CH4 Reforming; Nano-Ni; Nano support; Polyol; Coke; Stability;
Hydrogen production from CO2-free thermal decomposition of methane: Design and on-sun testing of a tube-type solar thermochemical reactor by Stéphane Abanades; Hiroyuki Kimura; Hiroyuki Otsuka (153-162).
This study addresses the development of a solar thermochemical reactor for CO2-free production of hydrogen from solar-aided methane decomposition. The developed lab-scale solar reactor basically pertaining to the indirect heating concept is chiefly based on a tube-type configuration in tandem with a cavity receiver. The reactor design and performance prediction were first appraised via 3-dimensional CFD thermal simulation as a function of internal geometry. The model including coupled heat/mass transfer and chemical reaction aimed to simulate the reactor in order to determine the temperature distribution and the conditions for maximum reactor efficiency. The designed 1 kW solar reactor was then constructed and installed for reaction testing at the focus of a 2 m-diameter parabolic solar concentrator. Solar CH4 decomposition experiments were performed between 1300 and 1400 °C to demonstrate the feasibility of hydrogen production and the reliability of the solar process using the developed reactor concept, and the results were used to validate simulations. Regarding the estimated kinetic parameters, the best fitting was obtained for an activation energy of 320 kJ/mol and a pre-exponential factor of 1011 s− 1. The chemical conversion was improved when increasing the temperature or decreasing the inlet gas flow rate or the CH4 mole fraction. A maximum CH4 conversion (resp. H2 yield) of 90% (resp. 85%) was achieved at 1400 °C and the thermochemical reactor efficiency reached 5% for the highest CH4 content in the feed.
Keywords: Methane cracking; Splitting; Pyrolysis; Hydrogen; Solar reactor; Thermochemistry;
Optimizing the gasification operating conditions of forest residues by coupling a two-stage equilibrium model with a response surface methodology by Valter Silva; Abel Rouboa (163-169).
A response surface methodology (RSM) was combined with a thermodynamical dual stage model to optimize the hydrogen syngas yield and the cold gas efficiency from the gasification of forest residues. The studied factors were the temperature, the steam to biomass ratio (SBR) and the oxygen content. The selected factors and their corresponding ranges were based on pre-screening results obtained from the dual stage model. The hydrogen yield was the first studied response. The computed results were also compared with semi-industrial experimental data gathered from a bubbling fluidized bed gasifier. Equilibrium results differ from semi-industrial data but in both cases the hydrogen molar fraction shows similar responses regarding the effect of different operating conditions. It was concluded that the hydrogen molar composition increases with the temperature and SBR but decreases with the oxygen content. On the other hand, it was found that very near from the optimal conditions there are several sets of temperature/SBR/O2 content that could produce similar hydrogen outputs but at less energy demanding conditions and a new optimization making use of desirability functions was carried out considering also the cold gas efficiency. The optimization procedure indicated that changing the operating conditions considerable economical savings are possible without reducing the hydrogen yield and cold gas efficiency outputs.
Keywords: Gasification; Forest residues; Carbon boundary point; Hydrogen syngas yield; Response surface methodology; Thermodynamic dual stage model;
Novel fluidized bed dryer for biomass drying by Yuping Liu; Jianghong Peng; Yasuki Kansha; Masanori Ishizuka; Atsushi Tsutsumi; Dening Jia; Xiaotao T. Bi; C.J. Lim; Shahab Sokhansanj (170-175).
Biomass drying is performed mainly in rotary dryers, which occupy a large footprint. To explore the efficient drying of biomass, a fluidized bed dryer was proposed. Good circulation of biomass particles could be established in the fluidized bed without the use of inert particle or mechanical aids. The initial moisture content of the input sawdust affected its fluidization performance. For the drying of sawdust of high-moisture content, the fluidization behavior could be divided into three stages: partial fluidization, full fluidization with increasing drying rate, and full fluidization with decreasing drying rate. A high drying rate could be achieved because of the fast mass and heat transfer rate in the fluidized bed. The fluidized bed dryer has a drying performance similar to the binary mixture fluidized bed dryer but more compact, and requires no separation of dried biomass particles from the inert bed particles.
Keywords: Biomass; Fluidization; Drying; Solid circulation; Moisture content;
Aspects of Mg–Al mixed oxide activity in transesterification of rapeseed oil in a fixed-bed reactor by Petr Kutálek; Libor Čapek; Lucie Smoláková; David Kubička (176-181).
The performance of Mg–Al mixed oxides prepared from different types of precursors in transesterification of rapeseed oil was studied in a fixed-bed reactor. The structure and basicity of Mg–Al–K and Mg–Al–Na mixed oxides with 3.6 Mg/Al molar ratio were compared before and after the catalytic tests carried out at various reaction temperatures (115 and 140 °C) and residence times (0.7, 1.54 and 1.79 h). The maximum ester yield of 77% was obtained at 140 °C and residence time of 1.54 h. The ester yield was stable during 50 h of the experiment. It was associated with the negligible magnesium leaching from the solid catalyst into the liquid phases and the minimum change in the composition, structure and basicity of Mg–Al mixed oxides after the catalytic test.
Keywords: Transesterification; Mg–Al mixed oxide; Fixed-bed reactor;