Records with Subject: Reaction Engineering
Showing records 1 to 25 of 40. [First] Page: 1 2 Last
Investigation into the Catalytic Activity of Microporous and Mesoporous Catalysts in the Pyrolysis of Waste Polyethylene and Polypropylene Mixture
Kaixin Li, Shao Wee Lee, Guoan Yuan, Junxi Lei, Shengxuan Lin, Piyarat Weerachanchai, Yanhui Yang, Jing-Yuan Wang
November 28, 2018 (v1)
Keywords: catalytic pyrolysis, mesoporous catalyst, microporous catalyst, plastic recycling, polyethylene (PE), polypropylene (PP)
Catalytic pyrolysis behavior of synthesized microporous catalysts (conventional Zeolite Socony Mobil⁻5 (C-ZSM-5), highly uniform nanocrystalline ZSM-5 (HUN-ZSM-5) and β-zeolite), Mesoporous catalysts (highly hydrothermally stable Al-MCM-41 with accessible void defects (Al-MCM-41(hhs)), Kanemite-derived folded silica (KFS-16B) and well-ordered Al-SBA-15 (Al-SBA-15(wo)) were studied with waste polyethylene (PE) and polypropylene (PP) mixture which are the main constituents in municipal solid waste. All the catalysts were characterized by Brunauer-Emmett-Teller (BET), X-ray powder diffraction (XRD), and NH3-temperature programmed desorption (TPD). The results demonstrated that microporous catalysts exhibited high yields of gas products and high selectivity for aromatics and alkene, whereas the mesoporous catalysts showed high yields of liquid products with considerable amounts of aliphatic compounds. The differences between the microporous and mesoporous catalysts could be attributed to t... [more]
Hydrothermal Conversion of Neutral Sulfite Semi-Chemical Red Liquor into Hydrochar
Ramy Gamgoum, Animesh Dutta, Rafael M. Santos, Yi Wai Chiang
November 28, 2018 (v1)
Keywords: ash content, higher heating value, hydrochar, hydrothermal conversion, red liquor, thermogravimetric analysis
Hydrochar was produced from neutral sulfite semi-chemical (NSSC) red liquor as a possible bio-based solid fuel for use in power generation facilities. Hydrothermal conversion (HTC) experiments were conducted using a fixed liquor-to-water volume ratio of 1:8 and reaction time of 3 h. Solutions were processed using different chemical additives, pH and temperature conditions to determine the optimum conditions required for producing a high energy content solid fuel. The hydrochar samples produced were analyzed by ultimate, thermogravimetric (TGA) and Fourier transform infrared spectroscopy (FTIR) analyses to determine physicochemical properties that are important for utilization as a fuel. The residual process liquids were also analyzed to better understand the effect of HTC process conditions on their properties. It was determined that the optimum conditions for producing a solid fuel was at a reaction temperature of 250 °C, in the presence of acetic acid at pH 3. The maximum energy cont... [more]
Distribution of Clay Minerals in Light Coal Fractions and the Thermal Reaction Products of These Clay Minerals during Combustion in a Drop Tube Furnace
Sida Tian, Yuqun Zhuo, Zhonghua Zhan, Xinqian Shu, Zhizhong Kang
November 28, 2018 (v1)
Keywords: aluminosilicate components, ash formation, coal slagging characteristics, density separation, mineral matter distribution
To estimate the contribution of clay minerals in light coal fractions to ash deposition in furnaces, we investigated their distribution and thermal reaction products. The light fractions of two Chinese coals were prepared using a 1.5 g·cm−3 ZnCl₂ solution as a density separation medium and were burned in a drop-tube furnace (DTF). The mineral matter in each of the light coal fractions was compared to that of the relevant raw coal. The DTF ash from light coal fractions was analysed using hydrochloric acid separation. The acid-soluble aluminium fractions of DTF ash samples were used to determine changes in the amorphous aluminosilicate products with increasing combustion temperature. The results show that the clay mineral contents in the mineral matter of both light coal fractions were higher than those in the respective raw coals. For the coal with a high ash melting point, clay minerals in the light coal fraction thermally transformed more dehydroxylation products compared with those i... [more]
Experimental Attempts to Investigate the Influence of Petrographic Properties on Drying Characteristics of Lignite in Superheated Steam Atmosphere
Anna Sciazko, Yosuke Komatsu, Marcin Zakrzewski, Taro Akiyama, Akira Hashimoto, Naoki Shikazono, Shozo Kaneko, Shinji Kimijima, Janusz S. Szmyd, Yoshinori Kobayashi
November 27, 2018 (v1)
Keywords: drying characteristic, lignite upgrading, low-rank coal (LRC), superheated steam drying, Turow lignite
A superheated steam fluidized bed dryer (SSFBD) in a self-heat recuperative configuration has a great potential of improving thermal efficiency of a lignite-fired power plant by recovering both of latent heat of vaporization of water kept in the fuel and part of sensible heat during the fuel processing. However, the optimal design of the dryer requires the fundamental knowledge of drying characteristics in respect to the individual properties of the utilized fuel. Experimental investigation to determine the correlation between a specific coal properties originated from geological background and its drying characteristics is thus the major concern in this paper. The investigated lignite is a representative of Turoszow deposit in Poland. Experimental attempts unveiling drying kinetics were carried out for 5 mm and 10 mm diameter spherical samples in the superheated steam atmosphere in the temperature range of 110 °C⁻170 °C. Simultaneous and continuous measurements of changes in weight, s... [more]
Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle
Rahul Bhosale, Anand Kumar, Fares AlMomani, Ujjal Ghosh, Mohammad Saad Anis, Konstantinos Kakosimos, Rajesh Shende, Marc A. Rosen
November 27, 2018 (v1)
Keywords: computational analysis, Hydrogen, samarium oxide, solar thermochemical, thermodynamics, water splitting
The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based) step drives the thermal reduction of Sm₂O₃ into Sm and O₂. The second (non-solar) step corresponds to the production of H₂ via a water splitting reaction and the oxidation of Sm to Sm₂O₃. The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (TH) is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (ηcycle) and solar-to-fuel energy conversion efficiency (ηsolar−to−fuel) attainable with and without heat recuperation. The results indicate that ηcycle and ηsolar−to−fuel both increase with decreasing TH, due to the reduction in oxygen partial pre... [more]
Performance of Natural Ester as a Transformer Oil in Moisture-Rich Environments
Kapila Bandara, Chandima Ekanayake, Tapan Saha, Hui Ma
November 27, 2018 (v1)
Keywords: acidity, ageing, colour, dielectric dissipation factor (DDF), hydrolysis, mineral oil, natural ester (NE), oxidation, viscosity
Interest has risen among utilities in using natural ester (NE) insulating oils in transformers as a substitute for conventional mineral oil. However, present understanding on aging behaviour of NE-paper composite insulation system and knowledge on application of existing condition monitoring tools for NE-based insulation are inadequate. This limits the cost effective and reliable field applications of NE insulating oil. To pave the way the application of NE-based insulation in transformers, a systematic study has been performed to compare the aging behaviour of transformer grade pressboard (PB) impregnated in NE and conventional mineral oil. Applicability of a number of chemical and physical parameters, including acidity value, dielectric dissipation factor (DDF), viscosity, and colour for assessing the quality of NE insulating oil is also discussed in this paper. Comparisons are made based on the limiting values provided in the related IEEE Standard and properties of mineral oil under... [more]
An Experimental Study on the Potential Usage of Acetone as an Oxygenate Additive in PFI SI Engines
Lei Meng, Chunnian Zeng, Yuqiang Li, Karthik Nithyanandan, Timothy H. Lee, Chia-fon Lee
November 27, 2018 (v1)
Keywords: acetone, Ethanol, Gasoline, PFI, SI engine
To face the challenges of fossil fuel shortage and stringent emission norms, there is growing interest in the potential usage of alternative fuels such as bio-ethanol and bio-butanol in internal combustion engines. More recently, Acetone⁻Butanol⁻Ethanol (ABE), the intermediate product of bio-butanol fermentation, has been gaining a lot of attention as an alternative fuel. The literature shows that the acetone in the ABE blends plays an important part in improving the combustion performance and emissions, owing to its higher volatility. Acetone and ethanol are the low-value byproducts during bio-butanol production, so using acetone and ethanol as fuel additives may have both economic and environmental benefits. This study focuses on the differences in combustion, performance and emission characteristics of a port-injection spark-ignition engine fueled with pure gasoline (G100), ethanol-containing gasoline (E10 and E30) and acetone-ethanol-gasoline blends (AE10 and AE30 at A:E volumetric... [more]
Catalytic Intermediate Pyrolysis of Napier Grass in a Fixed Bed Reactor with ZSM-5, HZSM-5 and Zinc-Exchanged Zeolite-A as the Catalyst
Isah Yakub Mohammed, Feroz Kabir Kazi, Suzana Yusup, Peter Adeniyi Alaba, Yahaya Muhammad Sani, Yousif Abdalla Abakr
November 27, 2018 (v1)
Keywords: bio-oil characterization, catalytic deoxygenation, intermediate pyrolysis, Napier grass, zeolite
The environmental impact from the use of fossil fuel cum depletion of the known fossil oil reserves has led to increasing interest in liquid biofuels made from renewable biomass. This study presents the first experimental report on the catalytic pyrolysis of Napier grass, an underutilized biomass source, using ZSM-5, 0.3HZSM-5 and zinc exchanged zeolite-A catalyst. Pyrolysis was conducted in fixed bed reactor at 600 °C, 30 °C/min and 7 L/min nitrogen flow rate. The effect of catalyst-biomass ratio was evaluated with respect to pyrolysis oil yield and composition. Increasing the catalyst loading from 0.5 to 1.0 wt % showed no significant decrease in the bio-oil yield, particularly, the organic phase and thereafter decreased at catalyst loadings of 2.0 and 3.0 wt %. Standard analytical methods were used to establish the composition of the pyrolysis oil, which was made up of various aliphatic hydrocarbons, aromatics and other valuable chemicals and varied greatly with the surface acidity... [more]
Catalytic Pyrolysis of Wild Reed over a Zeolite-Based Waste Catalyst
Myung Lang Yoo, Yong Ho Park, Young-Kwon Park, Sung Hoon Park
November 27, 2018 (v1)
Keywords: bio-oil, fast pyrolysis, waste fluidized catalytic cracking (FCC) catalyst, wild reed
Fast catalytic pyrolysis of wild reed was carried out at 500 °C. Waste fluidized catalytic cracking (FCC) catalyst disposed from a petroleum refinery process was activated through acetone-washing and calcination and used as catalyst for pyrolysis. In order to evaluate the catalytic activity of waste FCC catalyst, commercial HY zeolite catalyst with a SiO₂/Al₂O₃ ratio of 5.1 was also used. The bio-oil produced from pyrolysis was analyzed using gas chromatography/mass spectrometry (GC/MS). When the biomass-to-catalyst ratio was 1:1, the production of phenolics and aromatics was promoted considerably by catalysis, whereas the content of oxygenates was affected little. Significant conversion of oxygenates to furans and aromatics was observed when the biomass-to-catalyst ratio of 1:10 was used. Activated waste FCC catalyst showed comparable catalytic activity for biomass pyrolysis to HY in terms of the promotion of valuable chemicals, such as furans, phenolics and aromatics. The results of... [more]
Comparing the Bio-Hydrogen Production Potential of Pretreated Rice Straw Co-Digested with Seeded Sludge Using an Anaerobic Bioreactor under Mesophilic Thermophilic Conditions
Asma Sattar, Chaudhry Arslan, Changying Ji, Sumiyya Sattar, Irshad Ali Mari, Haroon Rashid, Fariha Ilyas
November 27, 2018 (v1)
Keywords: bio-hydrogen production, kinetic parameters, pretreatments, response surface methodology, volatile fatty acids
Three common pretreatments (mechanical, steam explosion and chemical) used to enhance the biodegradability of rice straw were compared on the basis of bio-hydrogen production potential while co-digesting rice straw with sludge under mesophilic (37 °C) and thermophilic (55 °C) temperatures. The results showed that the solid state NaOH pretreatment returned the highest experimental reduction of LCH (lignin, cellulose and hemi-cellulose) content and bio-hydrogen production from rice straw. The increase in incubation temperature from 37 °C to 55 °C increased the bio-hydrogen yield, and the highest experimental yield of 60.6 mL/g VSremoved was obtained under chemical pretreatment at 55 °C. The time required for maximum bio-hydrogen production was found on the basis of kinetic parameters as 36 h⁻47 h of incubation, which can be used as a hydraulic retention time for continuous bio-hydrogen production from rice straw. The optimum pH range of bio-hydrogen production was observed to be 6.7 ± 0.... [more]
Catalytic Flash Pyrolysis of Biomass Using Different Types of Zeolite and Online Vapor Fractionation
Ali Imran, Eddy A. Bramer, Kulathuiyer Seshan, Gerrit Brem
November 27, 2018 (v1)
Keywords: Biomass, catalytic pyrolysis, fractionation, zeolites
Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrading before it can be used as a transportation fuel. In this work, a high quality bio-oil has been produced using a novel approach where flash pyrolysis, catalysis and fractionation of pyrolysis vapors using two stage condensation are combined in a single process unit. A bench scale unit of 1 kg/h feedstock capacity is used for catalytic pyrolysis in an entrained down-flow reactor system equipped with two-staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low catalyst/biomass ratios did not show any significant improvements in the bio-oil quality, while high catalyst/biomass ratios showed an effective deoxygenation of the bio-oil. The application of zeolites decreased the organic liq... [more]
Computational Fluid Dynamic Analysis of Co-Firing of Palm Kernel Shell and Coal
Muhammad Aziz, Dwika Budianto, Takuya Oda
November 27, 2018 (v1)
Keywords: co-firing, Coal, computational fluid dynamics (CFD), exhaust gases, mass fraction, palm kernel shell (PKS), temperature
The increasing global demand for palm oil and its products has led to a significant growth in palm plantations and palm oil production. Unfortunately, these bring serious environmental problems, largely because of the large amounts of waste material produced, including palm kernel shell (PKS). In this study, we used computational fluid dynamics (CFD) to investigate the PKS co-firing of a 300 MWe pulverized coal-fired power plant in terms of thermal behavior of the plant and the CO₂, CO, O₂, NOx, and SOx produced. Five different PKS mass fractions were evaluated: 0%, 10%, 15%, 25%, and 50%. The results suggest that PKS co-firing is favorable in terms of both thermal behavior and exhaust gas emissions. A PKS mass fraction of 25% showed the best combustion characteristics in terms of temperature and the production of CO₂, CO, and SOx. However, relatively large amounts of thermal NOx were produced by high temperature oxidation. Considering all these factors, PKS mass fractions of 10%⁻15% e... [more]
Performance Evaluation of Palm Oil-Based Biodiesel Combustion in an Oil Burner
Abdolsaeid Ganjehkaviri, Mohammad Nazri Mohd Jaafar, Seyed Ehsan Hosseini, Anas Basri Musthafa
November 16, 2018 (v1)
Keywords: combustion, equivalence ratio, NOx, oil burner, palm oil
This paper presents an experimental investigation of the combustion characteristics of palm methyl ester (PME), also known as palm oil-based biodiesel, in an oil burner system. The performance of conventional diesel fuel (CDF) and various percentages of diesel blended with palm oil-based biodiesel is also studied to evaluate their performance. The performance of the various fuels is evaluated based on the temperature profile of the combustor’s wall and emissions, such as nitrogen oxides (NOx) and carbon monoxide (CO). The combustion experiments were conducted using three different oil burner nozzles (1.25, 1.50 and 1.75 USgal/h) under lean (equivalence ratio (Φ) = 0.8), stoichiometric (Φ = 1) and rich fuel (Φ = 1.2) ratio conditions. The results show that the rate of emission formation decreases as the volume percent of palm biodiesel in a blend increases. PME combustion tests present a lower temperature inside the chamber compared to CDF combustion. High rates of NOx formation occur u... [more]
Overcoming the Fundamental Limit: Combustion of a Hydrogen-Oxygen Mixture in Micro- and Nano-Bubbles
Vitaly Svetovoy, Alexander Postnikov, Ilia Uvarov, Remco Sanders, Gijs Krijnen
November 16, 2018 (v1)
Keywords: combustion, microsystems, nanobubbles
Combustion reactions quench in small volumes due to fast heat escape via the volume boundary. Nevertheless, the reaction between hydrogen and oxygen was observed in nano- and micro-bubbles. The bubbles containing a mixture of gases were produced in microsystems using electrochemical decomposition of water with a fast switching of voltage polarity. In this paper, we review our experimental results on the reaction in micro- and nano-bubbles and provide their physical interpretation. Experiments were performed using microsystems of different designs. The process was observed with a stroboscope and with a vibrometer. The latter was used to measure the gas concentration in the electrolyte and to monitor pressure in a reaction chamber covered with a flexible membrane. Information on the temperature was extracted from the Faraday current in the electrolyte. Since the direct observation of the combustion is complicated by the small size and short time scale of the events, special attention is... [more]
Effects of Oxygen Content of Fuels on Combustion and Emissions of Diesel Engines
Haiwen Song, Kelly Sison Quinton, Zhijun Peng, Hua Zhao, Nicos Ladommatos
October 23, 2018 (v1)
Keywords: diesel fuel, NOx emissions, oxygen content, oxygenated fuel, smoke
Effects of oxygen content of fuels on combustion characteristics and emissions were investigated on both an optical single cylinder direct injection (DI) diesel engine and a multi-cylinder engine. Three fuels were derived from conventional diesel fuel (Finnish City diesel summer grade) by blending Rapeseed Methyl Ester (RME) or Diglyme and Butyl-Diglyme of different quantities to make their oxygen content 3%, 3% and 9%, respectively. The experimental results with three tested fuels show that the fuel spray development was not affected apparently by the oxygenating. Compared with the base fuel, the ignition delay to pilot injection was shortened by 0%, 11% and 19% for three oxygenated fuels, respectively. The ignition delay to main injection was shortened by 10%, 19% and 38%, respectively. With regard to emissions, the smoke level was reduced by 24% to 90%, depending on fuel properties and engine running conditions. The penalties of increased NOx emissions and fuel consumption were up t... [more]
Generation of Hydrogen, Lignin and Sodium Hydroxide from Pulping Black Liquor by Electrolysis
Guangzai Nong, Zongwen Zhou, Shuangfei Wang
October 22, 2018 (v1)
Keywords: black liquor, electrolysis, Energy, Hydrogen, lignin
Black liquor is generated in Kraft pulping of wood or non-wood raw material in pulp mills, and regarded as a renewable resource. The objective of this paper was to develop an effective means to remove the water pollutants by recovery of both lignin and sodium hydroxide from black liquor, based on electrolysis. The treatment of a 1000 mL of black liquor (122 g/L solid contents) consumed 345.6 kJ of electric energy, and led to the generation of 30.7 g of sodium hydroxide, 0.82 g of hydrogen gas and 52.1 g of biomass solids. Therefore, the recovery ratios of elemental sodium and biomass solids are 80.4% and 76%, respectively. Treating black liquor by electrolysis is an environmentally friendly technology that can, in particular, be an alternative process in addressing the environmental issues of pulping waste liquor to the small-scale mills without black liquor recovery.
Low-Cost Feedstock Conversion to Biodiesel via Ultrasound Technology
Omotola Babajide, Leslie Petrik, Bamikole Amigun, Farouk Ameer
October 22, 2018 (v1)
Keywords: biodiesel, conversion efficiency, glycerol, transesterification, ultrasound
Biodiesel has attracted increasing interest and has proved to be a good substitute for fossil-based fuels due to its environmental advantages and availability from renewable resources such as refined and waste vegetable oils. Several studies have shown that biodiesel is a better fuel than the fossil-derived diesel in terms of engine performance, emissions reduction, lubricity and environmental benefits. The increasing popularity of biodiesel has generated great demand for its commercial production methods, which in turn calls for the development of technically and economically sound process technologies. This paper explores the applicability of ultrasound in the optimization of low-cost feedstock ⁻ in this case waste cooking oil ⁻ in the transesterification conversion to biodiesel. It was found that the conversion efficiency of the waste oil using ultrasound was higher than with the mechanical stirring method. The optimized variables of 6:1 methanol/oil ratio at a reaction temperature... [more]
Recent Advances in Direct Coal Liquefaction
Hengfu Shui, Zhenyi Cai, Chunbao Xu
October 22, 2018 (v1)
Keywords: Biomass, catalysts, co-liquefaction, coal pre-treatment, direct coal liquefaction (DCL), influencing factors, processes
The growing demand for petroleum, accompanied by the declining petroleum reserves and the concerns over energy security, has intensified the interest in direct coal liquefaction (DCL), particularly in countries such as China which is rich in coal resources, but short of petroleum. In addition to a general introduction on the mechanisms and processes of DCL, this paper overviews some recent advances in DCL technology with respect to the influencing factors for DCL reactions (temperature, solvent, pressure, atmospheres, etc.), the effects of coal pre-treatments for DCL (swelling, thermal treatment, hydrothermal treatment, etc.), as well as recent development in multi-staged DCL processes, DCL catalysts and co-liquefaction of coal with biomass.
Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl₂: A Kinetic Investigation
Abiney L. Cardoso, Soraia Cristina Gonzaga Neves, Marcio J. Da Silva
October 15, 2018 (v1)
Keywords: Biodiesel, ethanolysis, free fatty acids, Tin chloride catalyst
The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs) is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel. Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a basecatalyzed transesterification of the triglycerides. Commonly, the acid H₂SO₄ is the catalyst on the first step of this process. It must be said, however, that major drawbacks such as substantial reactor corrosion and the great generation of wastes, including the salts formed due to neutralization of the mineral acid, are negative and virtually unsurmountable aspects of this protocol. In this paper, tin(II) chloride dihydrate (SnCl₂·2H₂O), an inexpensive Lewis acid, was evaluated as catalyst on the ethanolysis of oleic acid, which is the major component of several fat and veg... [more]
Waste Cooking Oil as an Alternate Feedstock for Biodiesel Production
Arjun B. Chhetri, K. Chris Watts, M. Rafiqul Islam
October 15, 2018 (v1)
Keywords: alternate energy, biodiesel, feedstock, fuel characterization, Waste cooking oil
As crude oil price reach a new high, the need for developing alternate fuels has become acute. Alternate fuels should be economically attractive in order to compete with currently used fossil fuels. In this work, biodiesel (ethyl ester) was prepared from waste cooking oil collected from a local restaurant in Halifax, Nova Scotia, Canada. Ethyl alcohol with sodium hydroxide as a catalyst was used for the transesterification process. The fatty acid composition of the final biodiesel esters was determined by gas chromatography. The biodiesel was characterized by its physical and fuel properties including density, viscosity, acid value, flash point, cloud point, pour point, cetane index, water and sediment content, total and free glycerin content, diglycerides and monoglycerides, phosphorus content and sulfur content according to ASTM standards. The viscosity of the biodiesel ethyl ester was found to be 5.03 mm²/sec at 40oC. The viscosity of waste cooking oil measured in room temperature (... [more]
Combustion Characteristics and NOx Emission through a Swirling Burner with Adjustable Flaring Angle
Yafei Zhang, Rui Luo, Yihua Dou, Qulan Zhou
September 21, 2018 (v1)
Keywords: combustion adjustment, flaring angle, fuel rich/lean combustion, low load, swirling burner
A swirling burner with a variable inner secondary air (ISA) flaring angle β is proposed and a laboratory scale opposed-firing furnace is built. Temperature distribution and NOx emission are designedly measured. The combustion characteristics affected by variable β are experimentally evaluated from ignition and burnout data. Meanwhile, NOx reduction by the variable β is analyzed through emissions measurements. Different inner/outer primary coal-air concentration ratios γ, thermal loads and coal types are considered in this study. Results indicate that β variation provides a new approach to promote ignition and burnout, as well as NOx emission reduction under conditions of fuel rich/lean combustion and load variation. The recommended β of a swirling burner under different conditions is not always constant. The optimal βopt of the swirling burner under all conditions for different burning performance are summarized in the form of curves, which could provide reference for exquisite combust... [more]
Autoignition Behavior of an Ethanol-Methylcellulose Gel Droplet in a Hot Environment
Donggi Lee, Jonghan Won, Seung Wook Baek, Hyemin Kim
September 21, 2018 (v1)
Keywords: autoignition, combustion, droplet, Ethanol, gel propellant
Autoignition of an ethanol-based gel droplet was experimentally investigated by adding 10 wt % of methylcellulose as gellant to liquid ethanol. Experimental studies of the ignition behavior of the gel droplet were found to be quite rare. The initial droplet diameter was 1.17 ± 0.23 mm. The gel droplet was suspended on a K-type thermocouple and its evaporation, ignition and combustion characteristics were evaluated and compared with pure ethanol at an ambient temperature of 600, 700, and 800 °C under atmospheric pressure conditions. The gel droplet exhibited swelling and vapor jetting phenomena. Before ignition, a linear decrease in droplet diameter followed by a sudden increase was repeatedly observed, which was caused by evaporation and swelling processes, respectively. Major droplet swelling was detected just before the onset of ignition at all temperatures. But no further swelling was detected after ignition. For the gel droplet, the ignition delay accounted for 93% of the droplet l... [more]
Migration and Transformation of Vanadium and Nickel in High Sulfur Petroleum Coke during Gasification Processes
Wei Li, Ben Wang, Jun Nie, Wu Yang, Linlin Xu, Lushi Sun
September 21, 2018 (v1)
Keywords: gasification, high sulfur petcoke, migration, nickel, sequential extraction, vanadium
The volatilization characteristics and occurrence forms of V and Ni in petroleum coke (petcoke) were investigated during steam (H₂O) and carbon dioxide (CO₂) gasification on a fixed bed reactor at 800⁻1100 °C. The Tessier sequential chemical extraction procedure was employed to determine the different forms of V and Ni. The results showed their volatilities were not dependent on the gasification atmosphere, but rather relied mainly on the reaction temperature. The CO₂ atmosphere accelerated the conversion of organic-bound nickel to residual form at low temperature and promoted Fe-Mn oxides formation at high temperature. However, the H₂O atmosphere was conducive to form vanadium bound to Fe-Mn oxides and promoted the decomposition of residual forms. In addition, the thermodynamic equilibrium calculations showed the volatilization of Ni mainly released Ni₃S₂ between 800⁻1100 °C. The H₂O atmosphere was favorable to generate the more stable NixSy compound, thereby suppressing the volatiliz... [more]
Nitric Acid Pretreatment of Jerusalem Artichoke Stalks for Enzymatic Saccharification and Bioethanol Production
Urszula Dziekońska-Kubczak, Joanna Berłowska, Piotr Dziugan, Piotr Patelski, Katarzyna Pielech-Przybylska, Maria Balcerek
September 21, 2018 (v1)
Keywords: acid pretreatment, alkali pretreatment, enzymatic hydrolysis, ethanol fermentation, Jerusalem artichoke, lignocellulose, nitric acid
This paper evaluated the effectiveness of nitric acid pretreatment on the hydrolysis and subsequent fermentation of Jerusalem artichoke stalks (JAS). Jerusalem artichoke is considered a potential candidate for producing bioethanol due to its low soil and climate requirements, and high biomass yield. However, its stalks have a complexed lignocellulosic structure, so appropriate pretreatment is necessary prior to enzymatic hydrolysis, to enhance the amount of sugar that can be obtained. Nitric acid is a promising catalyst for the pretreatment of lignocellulosic biomass due to the high efficiency with which it removes hemicelluloses. Nitric acid was found to be the most effective catalyst of JAS biomass. A higher concentration of glucose and ethanol was achieved after hydrolysis and fermentation of 5% (w/v) HNO₃-pretreated JAS, leading to 38.5 g/L of glucose after saccharification, which corresponds to 89% of theoretical enzymatic hydrolysis yield, and 9.5 g/L of ethanol. However, after f... [more]
Combustion of Flax Shives, Beech Wood, Pure Woody Pseudo-Components and Their Chars: A Thermal and Kinetic Study
Nourelhouda Boukaous, Lokmane Abdelouahed, Mustapha Chikhi, Abdeslam-Hassen Meniai, Chetna Mohabeer, Taouk Bechara
September 21, 2018 (v1)
Keywords: Biomass, combustion, kinetic parameters, thermal characteristics, thermogravimetric analysis
Thermogravimetric analysis was employed to investigate the combustion characteristics of flax shives, beech wood, hemicellulose, cellulose, lignin, and their chars. The chars were prepared from raw materials in a fixed-bed reactor at 850 °C. In this study, the thermal behavior based on characteristic temperatures (ignition, maximum, and final temperatures), burnout time and maximum rate was investigated. The kinetic parameters for the combustion of different materials were determined based on the Coats-Redfern approach. The results of our study revealed that the combustion of pure pseudo-components behaved differently from that of biomass. Indeed, principal component analysis showed that the thermal behavior of both biomasses was generally similar to that of pure hemicellulose. However, pure cellulose and lignin showed different behaviors compared to flax shives, beech wood, and hemicellulose. Hemicellulose and cellulose chars had almost the same behaviors, while being different from b... [more]
Showing records 1 to 25 of 40. [First] Page: 1 2 Last
[Show All Subjects]