A comprehensive experimental investigation of combustion and heat release characteristics of a biodiesel (hazelnut kernel oil methyl ester) fueled direct injection compression ignition engine

In the present study, hazelnut (Corylus avellana L.) kernel oil was transesterified with methanol using potassium hydroxide as catalyst to obtain biodiesel and a comprehensive experimental investigation of combustion (cylinder gas pressure, rate of pressure rise, ignition delay) and heat release (rate of heat release, cumulative heat release, combustion duration and center of heat release) parameters of a direct injection compression ignition engine running with biodiesel and its blends with diesel fuel was carried out. Experiment parameters included the percentage of biodiesel in the blend, engine load, injection timing, injection pressure, and compression ratio. Results showed that hazelnut kernel oil methyl ester and its blends with diesel fuel can be used in the engine without any modification and undesirable combustion and heat release characteristics were not observed. The modifications such as increasing of injection timing, compression ratio, and injection pressure provided significant improvement in combustion and heat release characteristics.     

Sedimentation in biodiesel and Ultra Low Sulfur Diesel Fuel blends

A biodiesel storage stability study was conducted on Ultra Low Sulfur Diesel Fuel (ULSDF) and three biodiesel fuels (B100), including a Tallow-based Methyl Ester (TME), a Canola-based Methyl Ester (CME), and, a Yellow Grease Methyl Ester (YGME), and fuel blends (B5 and B20). The stability study was conducted over ten months (Aug 07-Jun 08) and consisted of storing fuel samples in quarter filled plastic and steel 20 L cans, in an unheated shed. Fuel cans were vented twice a week to ensure exposure of the fuel to air. Changes in Acid Number, kinematic viscosity and free water and sediments levels were monitored over the storage period. Temperature and relative humidity ranged from −25 °C to 35 °C and 25% to 100%, respectively. Acid Number and the viscosity did not increase beyond the uncertainty of the method used. Reference samples kept at 40 °C were used for comparison. Free water and sediment levels were barely above the detection limit of 0.003 mL/100 mL of fuel for CME and YGME and their blends. TME and its B20 blend displayed free water and sediment levels up to 0.05 mL/100 mL of fuel in February, after six months of storage. These values decreased considerably after the warm Summer months back to below 0.01 mL/100 mL. All free water and sediment levels were measured after fuel samples came to equilibrium with room temperature. The TME B5 free water and sediment levels remained low throughout the storage period. Proton Nuclear Magnetic Resonance (NMR) spectroscopy performed on particulates from the sediments revealed a similar composition but a slightly lower concentration for protons in alkenyl groups. The presence of these sediments was attributed to more saturated molecules coming out of solution in colder weather and very slowly going back to solution at room temperature.     

Fundamental combustion characteristics of palm methyl ester (PME) as alternative fuel for gas turbines

To investigate the combustion characteristics of palm methyl ester (PME) as an alternative fuel for gas turbines, combustion experiments at atmospheric pressure using high-temperature air (673 K) were performed. Chemical equilibrium calculations and investigations of fuel atomizing characteristics using a laser diffraction spray analyzer (LDSA) were also conducted. The results show that combustion characteristics of PME are similar to those of diesel fuel. Furthermore, it is indicated that NO_x emissions can be reduced by using PME instead of diesel fuel for gas turbines.     

Polycyclic Aromatic Sulfur Heterocycles in Desulfurized Diesel Fuels and Their Separation on a Novel Palladium(II)-Complex Stationary Phase

The lowering of the legal concentration of sulfur in fuels (in the European Union from 150 ppm at present to 50 ppm in 2004) not only affects the concentration but also the pattern of the polycyclic aromatic sulfur heterocycles (PASH) in the fuels. This pattern was studied for 12 diesel samples, most of which have been desulfurized. A separation of the PASHs and the polycyclic aromatic hydrocarbons becomes necessary at such sulfur levels. An efficient liquid chromatographic method for this is presented and involves a Pd(II)-containing complex based on 2-amino-1-cyclopentene-1-dithiocarboxylate covalently bonded to silica. The resultant PASH fraction can be analyzed by gas chromatography/flameionization detection.     

Experimental investigation of mineral diesel fuel, GTL fuel, RME and neat soybean and rapeseed oil combustion in a heavy duty on-road engine with exhaust gas aftertreatment

The effects of mineral diesel fuel, gas-to-liquid fuel, rapeseed methyl ester, neat soybean and neat rapeseed oil on injection, combustion, efficiency and pollutant emissions have been studied on a compression ignition heavy duty engine operated near full load and equipped with a combined exhaust gas aftertreatment system (oxidation catalyst, particle filter, selective catalytic NO_x reduction). In a first step, the engine calibration was kept constant for all fuels which led to differences in engine torque for the different fuels. In a second step, the injection duration was modified so that all fuels led to the same engine torque. In a third step, the engine was recalibrated in order to keep the NO_x emissions at an equal level for all fuels (injection pressure, injection timing, EGR rate). The experiments show that the critical NO_x emissions were higher (even behind the exhaust gas aftertreatment systems) for oxygenated fuels in case of the engine not being recalibrated for the fuel. GTL and the oxygenated fuels show lower emissions for some pollutants and higher efficiency after recalibration to equal NO_x levels.     

Electron beam flue gas treatment (EBFGT) technology for simultaneous removal of SO2 and NOx from combustion of liquid fuels

Electron beam flue gas treatment technology was applied for removal of SO₂ and NO_x from flue gas, emitted from combustion of high-sulfur fuel oils. The detailed study of this process was performed in a laboratory by irradiating the exhaust gas from the combustion of three grades of Arabian fuels with an electron beam from accelerator (800 keV, max. beam power 20 kW). SO₂ removal is mainly dependent on ammonia stoichiometry, flue gas temperature and humidity and irradiation doses up to 8 kGy. NO_x removal depends primarily on irradiation dose. High removal efficiencies up to 98% for SO₂ and up to 82% for NO_x were obtained under optimal conditions. The flue gas emitted from combustion of high-sulfur fuel oils, after electron beam irradiation, meets the stringent emission standards for both pollutants. The by-product, which is a mixture of ammonium sulphate and nitrate, can be used as a fertilizer as such or blended with other components to produce commercial agricultural fertilizer.     

<Superscript>1</Superscript>H NMR and Multivariate Calibration for the Prediction of Biodiesel Concentration in Diesel Blends

In this work, the use of ¹H-NMR spectroscopy and a statistical approach to the analysis of biodiesel concentrations in blends with conventional diesel is described. For this, we performed ¹H-NMR analyses using distinct mixtures of biodiesel from soybean and castor oil in mineral diesel, in concentrations ranging from 0.5 to 30%, and then we applied partial least squares regression (PLS) and principal components regression (PCR) to such data. So, six models were designed and they were evaluated through statistical parameters and through the analysis of four samples prepared in the laboratory. Briefly, a PLS model, obtained through the selection of aromatic, aliphatic and methoxy spectral regions, was quite suitable for the prediction of biodiesel concentrations greater than 2.0%. Deviations of real and predicted values were found to B2 commercial blends, indicating that this model can only be applied to blends exceeding a 2.0% level of biodiesel in petroleum diesel. In conclusion, the ¹H-NMR-PLS method is fairly useful for the quality control of biodiesel–diesel blends, whose commercialisation has increased in the last few years.     

Emission characteristics of diesel, gas to liquid, and biodiesel-blended fuels in a diesel engine for passenger cars

The need for diversification of energy sources and reducing various emissions including CO₂ emission in diesel engine can be met with alternative diesel fuels such as gas to liquid (GTL) and GTL–biodiesel blends. But there should be a clear understanding of the combustion and engine-out emission characteristics for alternative fuels. In this respect, an experimental study was conducted on a 2.0 L 4 cylinders turbocharged diesel engine fuelled with those alternative diesel fuels to investigate the engine-out emission characteristics under various steady-state engine operating conditions. The results revealed that noticeable decreases in THC (22–56%) and CO (16–52%) emissions for GTL–biodiesel blends were observed, whereas NOx emissions for GTL–biodiesel blends increased by a maximum of 12% compared to diesel. With regard to particle size distributions (PSDs) for GTL–biodiesel blends, the particulate matter (PM) number concentration in accumulation mode decreased, as a result of the excess oxygen content in biodiesel. Contrary to the tendency in the accumulation mode, there was a slight increase in the PM number concentration in the nucleation mode under the operating conditions wherein the exhaust gas recirculation (EGR) strategy was applied. The total PM number concentration for G + BD40 decreased by a maximum of 46% compared to that for diesel. From these results of enhanced emission characteristics compared to diesel and GTL fuel, the potential for the use of GTL–biodiesel blends could be confirmed.     

Minimizing fuel and environmental costs for a variable-load power plant (co-)firing fuel oil and natural gas Part 2. Optimization of load dispatch

A linear programming-based approach was applied to optimize the power (or load) distribution among 200-MW and 310-MW units of a 1330-MW power plant (co-)firing fuel oil and natural gas. The objective function for the optimization was the total costs, including “internal” (or fuel) and “external” (or environmental) costs, for the power plant meeting the current load demand. Both fuel and environmental costs (the latter being associated with NO_x, SO₃, SO₂ and CO₂ emissions) of the units were predicted for different fuel options. The total costs for an individual boiler unit were shown to be quasi-linear with the unit load. Optimal load dispatch over the units was determined using a typical daily load curve of the power plant, for distinct climatic seasons in Thailand. The time-domain savings of the total costs resulted from switching the units from actual to the optimized loads were quantified for this power plant.     

Estimation of the impact in the air quality by the use of clean fuels (fuel oil versus natural gas)

The extended use of fuels with high sulfur content (fuel oil) in the electric power industry represents one of the biggest concerns on air quality currently in Mexico. The organic sulfur compounds in the fuel oil are oxidized as SO_x during combustion, causing high concentration at the surface level near the releasing point. Shifting towards cleaner energy is crucial, however natural gas (NG) production is currently scarce and substantial investment is required to assure the NG supply to replace the fuel oil. Large investments should be made by the public and private sectors to replace heavy fuel oil use by NG. In order to support decision takers, this work assess the air quality impact due to cleaner energy use and determine the optimal NG and fuel oil mixture required to reduce substantially the SO₂ concentration. The dispersion model was applied to compare, against a base case, a set of artificial emissions scenarios with different fuel oil and NG mixtures. The model was previously validated against SO₂ field measurements performed at an Industrial Corridor, Mexico. The results show that increasing 40% the NG consumption, the SO₂, concentration in the air is reduced in 90%, therefore not further NG increasing is needed.     

超重力氧化还原法用于天然气脱硫的探索性研究

报道了用氮气和硫化氢的混合气模拟含硫天然气,在超重机中应用配合铁氧化还原法进行脱硫实验,研究了原料气中硫化氢浓度、原料气中气体流量、脱硫液流量、超重机转子转速和脱硫液pH值对H2S脱除率和气相传质系数的影响,确定了配合铁体系在超重机中适宜的反应条件。结果表明,在本实验条件下H2S脱除率稳定在99.9%左右。实验设备体积小,硫化氢脱除率稳定且高效。     

N-(3-甲酰吡啶)-脯氨酸甲酯的合成及其卷烟加香应用研究

以3-吡啶甲酸为起始原料,经酰氯化反应制成3-吡啶甲酰氯。另以脯氨酸为原料,经酰氯化后再与甲醇反应生成相应的氨基酸甲酯盐酸盐。在室温下,以三乙胺为缚酸剂,3-吡啶甲酰氯与氨基酸甲酯经过酰化反应生成目标产物N-(3-甲酰吡啶)-脯氨酸甲酯化合物。并将其应用于卷烟加香中,以改善卷烟制品品质。化合物结构通过1HNMR、13CNMR、IR和HRMS技术进行了表征。并对产物进行热重分析以及热裂解行为研究,分析鉴定出了40多种裂解产物,其多数为致香物质。对目标物进行卷烟加香评吸,结果表明,该物质能改善卷烟吸味,减轻卷烟吸食刺激性,增强香气。     

On the high‐gasification rate of Brazilian manganese ore in chemical‐looping combustion (CLC) for solid fuels

The high rate of char gasification observed when using a Brazilian manganese ore as compared to ilmenite is investigated in a batch fluidized‐bed reactor. Experiments were carried out at 970°C using petroleum coke, coal and wood char as fuel with a 50% H₂O in N₂ as fluidizing gas. A manufactured manganese oxygen carrier was also used, however, which presented a slower char conversion rate than the manganese ore. It is concluded that decrease in H₂ inhibition and oxygen release are unlikely to be the main responsible mechanisms for the ore's unexpected gasification rate. The ore was also mixed in different ratios with ilmenite and it was observed that the presence of even small amounts of ore in the bed resulted in increased gasification rate. Thus, the high‐gasification rate for the manganese ore could be due to a contribution from the impurities in the ore by catalyzing the gasification reaction. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4346–4354, 2013     

Catalyst modification and process design considerations for the oxidation of low concentrations of hydrogen sulfide in natural gas

Low concentrations of hydrogen sulfide (H₂S) in natural gas can be selectively oxidized over an activated carbon catalyst to elemental sulfur, water and a small fraction of sulfur dioxide (SO₂). Efforts to improve catalyst performance and product sulfur quality have been made by a) modification of the catalyst composition b) removal of the heavy hydrocarbons from the feed and c) choice of reaction conditions. The use of a guard bed to absorb heavy hydrocarbons and operation at elevated pressures show positive results. A preliminary flow diagram incorporating these findings has been prepared for a small commercial unit capable of processing sour natural gas containing 1.0% H₂S.     

Experimental study on the auto-ignition and combustion characteristics in the homogeneous charge compression ignition (HCCI) combustion operation with ethanol/n-heptane blend fuels by port injection

This article investigates the auto-ignition, combustion, and emission characteristics of homogeneous charge compression ignition (HCCI) combustion engines fuelled with n-heptane and ethanol/n-heptane blend fuels. The experiments were conducted on a single-cylinder HCCI engine using neat n-heptane, and 10%, 20%, 30%, 40%, and 50% ethanol/n-heptane blend fuels (by volume) at a fixed engine speed of 1800 r/min. The results show that, with the introduction of ethanol in n-heptane, the maximum indicated mean effective pressure (IMEP) can be expanded from 3.38 bar of neat n-heptane to 5.1 bar, the indicated thermal efficiency can also be increased up to 50% at large engine loads, but the thermal efficiency deteriorated at light engine load. Due to the much higher octane number of ethanol, the cool-flame reaction delays, the initial temperature corresponding the cool-flame reaction increases, and the peak value of the low-temperature heat release decreases with the increase of ethanol addition in the blend fuels. Furthermore, the low-temperature heat release is indiscernible when the ethanol volume increases up to 50%. In the case of the neat n-heptane and 10% ethanol/n-heptane blends, the combustion duration is very short due to the early ignition timing. For 20–50% ethanol/n-heptane blend fuels, the ignition timing is gradually delayed to the top dead center (TDC) by the ethanol addition. As a result, the combustion duration prolongs obviously at the same engine load when compared to the neat n-heptane fuel. At overall stable operation ranges, the HC emissions for n-heptane and 10–30% ethanol/n-heptane blends are very low, while HC emissions increase substantially for 40% and 50% ethanol/n-heptane blends. CO emissions show another tendency compared to HC emissions. At the engine load of 1.5–2.5 bar, CO emissions are very high for all fuels. Beside this range, CO emissions decrease both for large load and light load. In terms of operation stability of HCCI combustion, for a constant energy input, n-heptane shows an excellent repeatability and light cycle-to-cycle variation, while the cycle-to-cycle variation of the maximum combustion pressure and its corresponding crank angle, and ignition timing deteriorated with the increase of ethanol addition.     

On the evaluation of synthetic and natural ilmenite using syngas as fuel in chemical-looping combustion (CLC)

Chemical-looping combustion (CLC) is a combustion technique where the CO₂ produced is inherently separated from the rest of the flue gases with a considerably low energy penalty. For this reason, CLC has emerged as one of the more attractive options to capture CO₂ from fossil fuel combustion. When applying CLC with solid fuels, the use of a low cost oxygen carrier is highly important, and one such low cost oxygen carrier is the mineral ilmenite. The current work investigates the reactivity of several ilmenites, some which are synthetically produced by freeze granulation and two natural minerals, one Norwegian ilmenite and one South African ilmenite.     

Supported base metal catalysts for the preferential oxidation of carbon monoxide in the presence of excess hydrogen (PROX)

Supported base metal catalysts were tested for the preferential oxidation of CO (CO PROX). The catalysts we investigated covered a wide range of transition metals (Co, Cr, Cu, Ni, Zn) supported on oxides with very different acidic, basic and redox properties (MgO, La₂O₃, SiO₂–Al₂O₃, CeO₂, Ce_0.63Zr_0.37O₂). The influence of the metal loading (Cu), the support properties (acidity, basicity, redox, surface area) and the reaction conditions (reaction temperature, feed composition) on the catalyst activity and selectivity was evaluated. The activity of ceria and ceria–zirconia supported copper catalysts was comparable to the performances of noble metal samples classically used for the PROX reaction. In addition, Cu–CeO₂ catalysts showed a practically constant and high selectivity towards CO oxidation in the temperature range of 50–150 °C. Due to the strong synergetic effect between copper and ceria, only a small amount of copper (0.3 wt.%) was necessary to get an active catalyst. The best catalytic performances were obtained for the samples containing 1–3 wt.% copper. The presence of small copper particles in close interaction with the ceria support was shown to be responsible for the enhanced activity. Except for the hydrogen oxidation, no parallel reactions (CO or CO₂ methanation reactions, coking, RWGS) could be detected over these catalysts. Classically, an increase of the oxygen excess led to an increased CO conversion with a simultaneous loss of selectivity towards CO₂. Finally, the presence of CO₂ in the feed negatively affected the catalytic activity. This effect was attributed to the adsorption of CO₂ on the copper sites, probably as CO.     

Excimer fluorescence technique for study of polymer-segment mobility: applications to pyrene-labelled poly(methyl methacrylate) and poly(methyl acrylate) in solution

An excimer fluorescence technique for the study of polymer-segment mobility has been developed and applied to pyrene-labelled poly(methyl methacrylate) and poly(methyl acrylate) polymers in solution. The results of the study have been interpreted in terms of Kramers' theory for the crossing of a potential barrier by a particle embedded in a viscous medium. The results show that the internal viscosity has a solvent-independent part and lead to an estimate of the dimensionless internal viscosity parameter introduced by Cerf.