Fuel Processing Technology (v.96, #C)
Editorial Board (IFC).
Thermal behavior of phosphorus derivatives of hydrogenated cardanol by Maria Alexsandra de Sousa Rios; Selma Elaine Mazzetto (1-8).
Hydrogenated cardanol and its derivative, butylated cardanol, can be phosphorated using diethyl chlorophosphate or diphenyl chlorophosphate in chloroform to give ethyl or phenyl phosphates. The resulting products were characterized by GC–MS, FT-IR spectroscopy and their thermal behavior was evaluated by thermogravimetric analyses such as TG and DSC. Thermal parameters such as number of degradation steps, initial (Ti) and maximum (Tmax) degradation temperatures, loss of mass (∆m (%)) and the integral procedure decomposition temperature (IPDT) were determined. TG curves of ethyl and phenyl phosphates showed that phenyl phosphates are more stable than ethyl phosphates probably due to the high stability P―O―Caromatic bond. In ethyl phosphates, the effect of ethoxy group (O―C2H5) reduces thermal stability. For the phenyl phosphates, DSC measurements presented peak temperatures about 465.8 °C suggesting the possibility of application of these compounds as antioxidants for petrochemical products, for example lubricant oils.
Keywords: Thermogravimetry; Cashew Nut Shell Liquid; Integral procedure decomposition temperature;
Study of Cu–Ni/SiO2 catalyst prepared from a novel precursor, [Cu(H2O)6][Ni(dipic)2].2H2O/SiO2, for water gas shift reaction by Ali Reza Salehi Rad; Maryam Behzad Khoshgouei; Soheil Rezvani; Ali Reza Rezvani (9-15).
Silica-supported copper–nickel bimetallic catalyst was prepared from [Cu(H2O)6][Ni(dipic)2].2H2O/SiO2 precursor. The cationic–anionic complex, [Cu(H2O)6][Ni(dipic)2].2H2O, was prepared from the reaction of (NH4)2[Ni(dipic)2] with Cu(NO3)2.3H2O in water and characterized by elemental analysis, conductometric and various spectroscopy techniques such as FT-IR, UV–vis and atomic absorption. The physicochemical characteristics of both precursor and calcined catalyst were carried out using X-ray diffraction, thermal analysis methods (TGA and DSC), FT-infrared, scanning electron microscopy and BET specific surface area. The catalyst was evaluated for water gas shift reaction. When the Cu–Ni/SiO2 catalyst was used for water gas shift reaction at 300 °C and atmospheric pressure, the CO conversion and CO2 selectivity were about 97.83% and 98.67%, respectively, showing higher activity and selectivity than the reference catalyst prepared by impregnation conventional method.Silica-supported copper–nickel catalyst was prepared by thermal decomposition of [Cu(H2O)6][Ni(dipic)2].2H2O/SiO2 precursor . This catalyst showed high catalytic activity for water gas shift reaction at 300–380 °C.Display Omitted► The method of Cu–Ni/SiO2 catalyst preparation is a simple and suitable way. ► The Cu–Ni catalyst has the high catalytic activity for WGS reaction at 300–380 °C. ► This catalyst presents higher activity than those prepared from other methods.
Keywords: Novel precursor; [Cu(H2O)6][Ni(dipic)2].2H2O/SiO2; Bimetallic catalyst; Complex; Water gas shift reaction;
Determination of crude oil incompatibility regions by ellipsometry by P. Álvarez; J.L. Menendez; C. Berrueco; K. Rostani; M. Millan (16-21).
Crude oil incompatibility is a common problem in the oil industry and may lead to severe fouling of process units, such as the pre-distillation heat exchanger train. This work investigates the use of ellipsometry to evaluate the compatibility of crude oil blends. Two crude oils with predicted regions of compatibility and incompatibility were blended in several ratios and the formation of a denser phase was examined by ellipsometry. The procedure implies the evaluation of the real part of the refractive index of the crude oils and their mixtures, which can be linked to the density of the mixture. The ellipsometric measurements fit well theoretical predictions obtained using a Cauchy dielectric function for the pure crudes and the Maxwell-Garnett effective medium model for the mixtures. The regions of compatibility and incompatibility between the two crudes were checked against independent measurements of deposit formation by weight and predictions based on the insolubility and solubility blending numbers, showing good agreement.► Evaluation of compatibility of two crude oils with different paraffinic content. ► Determination of crude oil incompatible blends by weight and ellipsometry. ► Both methods determined similar fouling formation threshold. ► Ellipsometric measurements of crudes fitted theoretical models. ► Divergences from models in mixtures suggest formation of fouling precursors.
Keywords: Crude oil; Fouling; Ellipsometry;
Influence of jig frequency on the separation of coal from the Bonito seam — Santa Catarina, Brazil by N. Ferreira Feil; C. Hoffmann Sampaio; H. Wotruba (22-26).
The coal from the Barro Branco seam, which is widely used, is situated in the southern region of Brazil, State of Santa Catarina, and it is nearing depletion. The remaining coal from the Bonito seam in the same region is less known and it is characterized by the high percentage of near gravity material and ash content. This peculiarity makes it difficult to treat in the current processing plants, which use jigs for this purpose. This product should have ≤ 43% ash content for supplying Jorge Lacerda's thermal electric power plant. This study was carried out to investigate other routes and improvements for coal cleaning. Dry processing and jigging tests were conducted in Germany for this purpose. Dry processing was done using an X-ray sorter. Tests were also performed using a batch jig to study the influence of jig frequency on the separation of two coal fractions. It was found that the processing at a specific frequency of pulsation for this coal allows the concentration of a suitable product for the market with yield about 30%.► The effect of frequency of pulsation on jigging process. ► The coal as an alternative to keep the economy activities in the southern of Brazil. ► Beneficiation of coal from the Bonito seam, Brazil.
Keywords: Jig frequency; X-ray sorting; Coal preparation; Gravimetric beneficiation;
H2 production with CO2 capture by sorption enhanced chemical-looping reforming using NiO as oxygen carrier and CaO as CO2 sorbent by Magnus Rydén; Pedro Ramos (27-36).
A novel process for conversion of hydrocarbons to H2 has been examined. The process, sorption enhanced chemical-looping reforming, involves three interconnected reactor vessels. In the reforming reactor, hydrocarbon fuel is partially oxidized with oxygen provided via a solid oxygen carrier such as NiO. Resulting CO is shifted instantly to CO2 via sorption enhanced water–gas shift, facilitated by the capturing of CO2 with a solid CO2 sorbent such as CaO. Ni and CaCO3, are regenerated downstream in separate reactors. The process produces H2, CO2 and N2 of reasonable purity in separate streams, without need for additional gas separation equipment. The characteristics of the process have been examined by thermodynamic calculations and by process modeling. At 1 bar it could produce > 2.8 mol H2 with a purity of > 98 vol.% for each mol CH4 added as fuel, while capturing > 95% of added carbon as CO2. Increasing the pressure reduces the performance due to lower conversion of CH4. Involved reactions have also been examined in a fluidized-bed reactor at 600–750 °C, with particles of NiO and CaO as bed material and CH4 mixed with steam as fuel. The CH4 conversion was incomplete but the results fitted with theory and gas with a H2/(H2 + CO + CO2) ratio of more than 98% was produced at 600 °C.► A novel method to convert hydrocarbon fuels to H2 with inherent CO2 capture has been examined. ► The process is a hybrid between chemical-looping reforming and sorption enhanced reforming. ► Hydrocarbons are oxidized with solid NiO and steam and CO2 is captured by carbonation of CaO. ► Both reactions take place in one single reactor vessel at 600–750 °C. ► The process has been examined by modeling as well as by experiments in a fluidized bed reactor.
Keywords: Chemical-looping reforming; Calcium looping; Carbonate looping; Sorption enhanced reforming; Hydrogen; Carbon capture;
Testing of a highly reactive impregnated Fe2O3/Al2O3 oxygen carrier for a SR–CLC system in a continuous CLC unit by Pilar Gayán; Miguel A. Pans; María Ortiz; Alberto Abad; Luis F. de Diego; Francisco García-Labiano; Juan Adánez (37-47).
A Fe‐based oxygen carrier (OC) was evaluated for H2 production with CO2 capture by coupling steam reforming of methane and chemical‐looping combustion (CLC) processes (SR–CLC). The CLC system supplies the heat necessary to carry out the endothermic reformed reactions, using the PSA off‐gas as fuel. The Fe‐based OC was made by incipient hot impregnation using Al2O3 as support and was first characterized by TGA and batch fluidized bed reactor in order to determine its reactivity and its fluidization behavior. The OC behavior in a continuous CLC unit was evaluated using a simulated PSA off‐gas and methane as fuels. During 46 h of continuous operation, the OC never showed agglomeration or carbon deposition, and the attrition was moderate. It was found that the fuel composition has low effect on the combustion efficiency and full conversion can be obtained at 1153 K with an oxygen carrier‐to‐fuel ratio > 1.5. The solids inventory needed to fully convert methane or PSA off‐gas was lower than those found with other Fe‐based materials. These results were due to the positive effect of the alumina on the OC reactivity. Therefore, the Fe2O3/Al2O3 OC prepared by impregnation is suitable for burning a PSA off‐gas in the SR–CLC process.► An impregnated Fe2O3/Al2O3 carrier was evaluated for the SR–CLC process. ► The carrier was used in a continuous CLC unit to burn a PSA tail gas and CH4. ► Full conversion of PSA-offgass and CH4 at 880 °C was obtained. ► The metal inventory needed is much lower (50 kg/MWth) than for other Fe-based OC.
Keywords: Hydrogen; Steam reforming; Chemical looping combustion; CO2 capture; Oxygen carrier; Iron oxide;
Chemical and ecotoxicological properties of ashes produced in the co-combustion of coal and meat and bone meal in a fluidized bed reactor by Rui Barbosa; Nuno Lapa; Helena Lopes; Benilde Mendes (48-55).
The co-combustion of coal and meat and bone meal (MBM) is a possible energetic valorization route for this residue. Nevertheless, the properties of ashes produced need to be studied. To evaluate these properties, three combustion tests were performed in a fluidized bed reactor: 1) coal combustion; 2) coal + MBM (85% + 15%) co-combustion; 3) MBM combustion. The characterization of ashes was focused on the following aspects: (1) Determination of bulk content of Cr, Zn, Ni, Cu, Pb, Cd, Hg, As, Ba, Mo, Sb, Se, Ca, Na, Mg, Fe, Al and K; (2) Leaching properties of ashes based on the European Standard EN12457-2. The eluates were characterized for some of the metals referred above and for Cr VI, CN−, pH, Cl−, F−, SO4 2−, dissolved organic carbon and total dissolved solids. The eluates were also characterized for ecotoxicological levels by using the following bio-indicators: bacterium V. fischeri, microalgae S. capricornutum and microcrustacean D. magna. The ashes produced in the combustion of coal and co-combustion of coal + MBM have not shown evidences of ecotoxicity, while the ashes produced in the combustion of MBM were classified as ecotoxic. An assessment of the relationship between the chemical and the ecotoxicological properties of the ashes was performed. pH seemed to be the chemical parameter that most influences the ecotoxicological level of ashes.► The substitution of coal by MBM produced ashes with higher content of heavy metals. ► Similar leaching rates of heavy metals from the same type of ashes. ► The biological responses were, probably, associated with the pH of the eluates. ► More studies are needed to identify the causes of the levels of ecotoxicity. ► A methodology to correlate chemical and ecotoxicological properties was developed.
Keywords: Combustion; Coal; Meat and bone meal; Ashes; Chemical properties; Ecotoxicological properties;
Characterization of coals and their laboratory-prepared black carbon using advanced solid-state 13C nuclear magnetic resonance spectroscopy by Yuan Li; Xiaoyan Cao; Dongqiang Zhu; Mark A. Chappell; Lesley F. Miller; Jingdong Mao (56-64).
Lignite, anthracite, humic acid fraction of lignite, and their laboratory-prepared black carbon (BC) were characterized in detail by advanced solid state 13C NMR spectroscopy to examine how the differences in chemical structures of fuels (lignite and anthracite) would affect the structures of their BC. Anthracite was almost completely dominated by aromatics (96.9%), with very minor CCH3. Although lignite contained mostly aromatics (76.1%), significant aliphatics (21.3%) as well as small amounts of COO/N―C＝O and O-alkyls were also present. In addition, anthracite had more aromatic C―C groups than lignite. Their BC samples both exhibited increased oxygenated functional groups such as COO, aromatic C―O and O-alkyl groups, and concomitant decrease of aromatic C―H and nonpolar alkyls. The 1H― 13C recoupled long-range dipolar dephasing experiments indicated the growth of aromatic cluster sizes in BC. Although the aromaticity of anthracite was much larger than those of lignite and lignite humic acid, their aromatic cluster sizes were quite similar. The BC samples had much larger aromatic cluster sizes than anthracite despite their smaller aromaticities. Therefore, higher rank or higher aromaticity may not imply larger aromatic cluster size in coal. The structures of two BC samples were similar despite the contrasting structural differences of their original coals.► Anthracite has larger aromaticity and more aromatic C-C groups than lignite. ► BC structures are similar although their original coals are structurally distinct. ► BC samples have larger aromatic cluster sizes than their source fuels. ► Oxygenated functional groups increase in BC samples. ► Higher rank or aromaticity may not imply larger aromatic cluster size in coal.
Keywords: Lignite; Humic acid; Anthracite; Black carbon; Solid-state NMR;
A new method to calculate efficiency of randomly-packed distillation columns and its comparison with the methods utilized in ASPEN Plus by Hamidreza Sadeghifar; Alireza Sadeghifar (65-73).
In this paper, a unique and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of randomly-packed distillation columns. This method has potential advantages; e.g., unlike all the available methods, it can calculate efficiency without using any empirical mass transfer and hydraulic correlations, and without the need to estimate the operational and hydraulic parameters of an operating column. It, therefore, will be free of errors and limitations of such empirical items and can be used for efficiency calculation of any random packing including new ones.Along with an analysis of the proposed method, the paper also presents a thorough analysis of the drawbacks and restrictions of the well-known mass transfer methods utilized in the commercially simulation packages such as ASPEN Plus. From these analyses, a number of main conclusions regarding the relationship of the mass transfer coefficients and of efficiency with the phase flow rates are drawn, and relevant recommendations are made for future research. It is also concluded that developing new methods based on rate quantities rather than flux quantities, like the one proposed in this study, can eliminate the necessity of estimating effective interfacial area for mass transfer calculations of an operating column.Display Omitted► A new method for calculation of mass and heat transfer coefficients and efficiency. ► Usable for efficiency estimation of any random packing in distillation columns. ► Free of errors and restrictions of empirical mass transfer and hydraulic correlations. ► Discussing restrictions of the well-known mass transfer method of Onda, available in ASPEN Plus package. ► Considering the relationship of mass transfer coefficients and of efficiency with phase flow rates.
Keywords: Efficiency; Distillation; Random packing; Mass transfer coefficient;
SO3H-functionalized ionic liquids as efficient catalysts for the synthesis of bioadditives by Xiaoyuan Liao; Sheng-Guang Wang; Xiaomin Xiang; Yulei Zhu; Xichun She; Yongwang Li (74-79).
Three kinds of SO3H-functionalized Brønsted-acidic ionic liquids with different acidities were applied to the etherification of glycerol with tert-butyl alcohol. High conversion and good selectivity were obtained under mild conditions. Among the ionic liquids investigated, those having a HSO4 − anion afforded the highest glycerol conversion and those having a F3CSO3 − anion afforded the largest head product selectivity for glycerol etherification. The minimum-energy geometries and experimental results show that acidities and catalytic activities of ionic liquids are not only related to their structures but also to their immiscibility.
Keywords: Glycerol; Ethers; DFT; Acidic functionalized ionic liquids; Bioadditives;
Application of electrochemical oxidation as alternative treatment of produced water generated by Brazilian petrochemical industry by Jéssica H. Bezerra Rocha; Maésia M. Soares Gomes; Nedja Suely Fernandes; Djalma Ribeiro da Silva; Carlos A. Martínez-Huitle (80-87).
This paper presents the anodic oxidation of real produced water, generated by petroleum exploration of the Petrobras plant-Brazil, using platinum supported on Ti (Ti/Pt) and boron-doped diamond (BDD) anodes in an electrolytic batch cell. The influence of several operating parameters such as current, supporting electrolyte, agitation rate and temperature on the performance has been studied and the energy consumption has been also evaluated. Galvanostatic electrolysis at BDD leads to complete COD removal (98%) due to the high amounts of effective hydroxyl radicals and peroxodisulfates generated from water oxidation and the COD removal rate increases with rising applied current (from 15 to 60 mA cm− 2). Conversely, at Pt electrode, about 50% of COD removals were achieved by applying 15 and 30 mA cm− 2 of current density, and 80% of COD removal at 60 mA cm− 2. Although, the energy consumption and process time make useless anodic oxidation for complete treatment of petrochemical wastewaters; maybe, it can be a feasible process as a pre-treatment process reducing significantly the cost and time of treatment.Display Omitted
Keywords: Produced water; Water treatment; Electrochemical oxidation; Petrochemical pollution;
Sintering characteristics of sewage sludge ashes at elevated temperatures by Liang Wang; Geir Skjevrak; Johan E. Hustad; Morten G. Grønli (88-97).
In this work the sintering characteristics and mineral transformation behaviors of sewage sludge ash (SSA) at elevated temperatures were investigated by using ash fusion analyzer, X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray spectrometry (SEM/EDX). High initial fusion temperatures above 1100 °C were detected from the sewage sludge ashes (SSA 1 and SSA 2) with high Al contents. Corundum, quartz and calcium aluminum silicates were dominating crystalline phases identified from SSA 1 and SSA 2 sintered at elevated temperatures. For the SSA 3 with a high Fe content, low initial melting temperature of 994 °C was detected with observation of severe fusion behavior from the ash sintering tests. SEM analysis revealed that SSA 3 melted completely into a more homogeneous and continuous phase at high sintering temperatures. A significant amount of Fe bearing mineral phases and quartz (SiO2) was identified from the sintered SSA 3. Diffraction intensities of hematite (Fe2O3), quartz (SiO2) and alkali feldspar decreased with increasing sintering temperatures, suggesting interaction and re-assemblage of these mineral phases. In combining the XRD and SEM/EDX analyses, it is believed that formation of low melting temperature iron silicates is the main reason for sintering of SSA 3.
Keywords: Sewage sludge ash; Sintering; Mineral phase; X-ray analysis; SEM-EDX;
A novel kinetic study of H3PW12O40 - catalyzed oleic acid esterification with methanol via 1H NMR spectroscopy by Sergio Antonio Fernandes; Abiney Lemos Cardoso; Márcio José da Silva (98-103).
In this work, the H3PW12O40 heteropolyacid - catalyzed oleic acid esterification reaction with methanol was investigated via 1H NMR spectroscopy in situ. H3PW12O40 heteropolyacid has recently attracted significant attention due to its potential for application in the production of biodiesel, in either homogeneous or heterogeneous catalytic conditions. Although fatty acids esterification reaction has been known for some time, data is still scarce regarding kinetic and thermodynamic parameters, especially when catalyzed by non-conventional compounds such as H3PW12O40. Herein, a kinetic study utilizing 1H NMR spectroscopy in situ allows for evaluating the effects of temperature on reaction rate, and determining the activation energy along with thermodynamic constants including ΔG, ΔS and ΔH. Although used in homogeneous phase, the HPW catalyst was recovered and reutilized via a simple recycle protocol without activity loss. Additionally, the order of reaction in relation to both substrate and catalyst concentrations was also determined. NMR spectroscopy showed to be an efficient method of investigation and allows accurate measurement of the reaction rate and of thermodynamic parameters of the H3PW12O40 - catalyzed oleic acid esterification reactions.Kinetic data obtained by 1H NMR monitoring of the oleic acid esterification with methanol catalyzed by H3PW12O40 at different temperatures. Reactions conditions: HPW catalyst (0.00059 mmols, 0.89 mol %); oleic acid (0.0663 mmols); deuterated methanol (16. 31 mmols).Display Omitted
Keywords: Heteropolyacid; NMR spectroscopy; Kinetic study; Esterification;
Chemical looping combustion of a Chinese anthracite with Fe2O3-based and CuO-based oxygen carriers by Baowen Wang; Haibo Zhao; Ying Zheng; Zhaohui Liu; Rong Yan; Chuguang Zheng (104-115).
Chemical looping combustion (CLC) of coal has received great attention for its verified advantage in the inherent separation of CO2 without great cost penalty. It would be meaningful to adopt anthracite as fuel for CLC application in China due to its abundant reserve in China and also a great challenge for its low reactivity. A typical Chinese anthracite as Yang Quan (YQ) coal was selected in this research as a model fuel and its reaction with both synthesized CuO/Al2O3 and Fe2O3/Al2O3 oxygen carriers (OCs) was performed in a thermogravimetric analyzer (TGA) to investigate the reaction peculiarities involved. Fourier transform infrared spectroscopy (FTIR) was used to in-situ detect the emitted gasses from TGA. Field scanning electron microscopy/energy-dispersive X-ray spectrometry (FSEM-EDX) was used to study the morphology and elemental compositions present in the solid residues collected from the reaction of YQ with these two OCs, and the related phase was identified by X-ray diffraction (XRD). In order to further explore the reaction mechanisms involved, a more realistic reaction system with 426 species was designed for thermodynamic simulation. Through all these measures, two reaction stages were observed for the reaction of YQ with Fe2O3/Al2O3 or CuO/Al2O3 at 300–600 °C and 600–850 °C after dehydration, respectively. The maximum weight loss rate for YQ with CuO/Al2O3 at the second stage was pronounced enough to reach up to 2.8 wt.%/min, greatly higher than that of YQ with Fe2O3/Al2O3. The mixture conversion index for YQ with CuO/Al2O3 was far bigger than that of YQ with Fe2O3/Al2O3, which further indicated that CuO/Al2O3 was more suitable to YQ in CLC. At these two stages throughout 400 to 1100 °C, CuO and CuAl2O4 contained in CuO/Al2O3 OC were mainly reduced to Cu and Cu2O or CuAlO2 and Al2O3 by transfer of the lattice oxygen [O] involved to YQ in a sequential mode; however, above 800 °C, Cu2O and CuAlO2 were also produced through direct decomposition of CuO or CuAl2O4 by emission of gaseous oxygen O2, which was beneficial to the direct combustion of coal. During reaction of YQ with CuO/Al2O3 OC, active CuO was found to tend to react with various sulfur species produced from YQ pyrolysis and formed to Cu2S, but the Al2SiO5 was formed through the interaction of Al2O3 with SiO2 in the YQ, which resulted in the loss of the inert support involved in the CuO/Al2O3 OC and further degraded its reactivity to YQ due to the lower resistance to sintering.► OCs were prepared using the novel sol-gel combustion synthesis method. ► Reaction of the synthesized OCs with Chinese anthracite was performed. ► Effect of support Al2O3 on the reaction of the anthracite with OCs was studied. ► The reaction mechanisms involved were explored.
Keywords: Chemical looping combustion (CLC); Anthracite coal; CuO/Al2O3 and Fe2O3/Al2O3 oxygen carrier; TGA;
Competitive study on separation and characterization of microcrystalline waxes using two deoiling techniques by Nermen H. Mohamed (116-122).
One stage fractional crystallization and solvent extraction techniques have been used to separate different microcrystalline waxes grades with different characteristics from Suez crude petrolatum. One stage fractional crystallization has been done using butyl acetate as solvent at ambient temperature of 20 °C, at different dilution solvent ratios (S/F by weight) ranging from 2:1 to 8:1 and constant washing ratio of 2:1. While, solvent extraction technique has been done at different extraction temperatures and different solvent feed ratios (S/F by weight). The extraction solvents used are dimethyl-sulfoxide (DMS), N, N, dimethyl-acetamide (DMA), and N-methyl-2-pyrrolidone (NMP). The wax products are evaluated according to TAPPI-ASTM equation and petroleum wax specifications. The data revealed that solvent extraction technique is more suitable for deoiling Suez crude petrolatum than one stage fractional crystallization technique. Also, the resulting data revealed that DMA and NMP are suitable extracting solvents for isolating of microcrystalline waxes from Suez crude petrolatum. But, according to petroleum wax specifications, DMS is not a suitable solvent for separation of microcrystalline wax from Suez crude petrolatum.► Fractional crystallization &solvent extraction for deoiling petroleum waste by-product. ► Solvent extraction technique is more preferable. ► Obtained microcrystalline waxes according to TAAPI-ASTM equation and petroleum wax specifications.
Keywords: Microcrystalline waxes; Fractional crystallization; Solvent extraction; Petrolatum; Deoiling techniques;
Thermal behavior and kinetics of crude oils at low heating rates by differential scanning calorimeter by Mustafa Versan Kok (123-127).
The objective of this research was to investigate thermal behavior and kinetics of different origin crude oils in limestone matrix by differential scanning calorimeter (DSC) at low heating rates. In DSC experiments, three distinct reaction regions were identified in all of the crude oil + limestone mixtures known as low temperature oxidation (LTO), fuel deposition (FD) and high temperature oxidation (HTO) respectively. Kinetic analysis of the crude oil samples was determined by different models known as ASTM, Borchard-Daniels and Ozawa. Higher activation energy values were obtained in high temperature oxidation region.► In combustion with air, three transitional stages are detected at each heating rate. ► Higher heat of reactions and temperatures were seen as heating rate is increased. ► Activation energy of the crude oils were close to each other in all the models.
Keywords: Crude oil; Combustion; Kinetics; Differential scanning calorimeter; Thermal analysis;
Enhancement of stability and activity of Cu/ZnO/Al2O3 catalysts by colloidal silica and metal oxides additives for methanol synthesis from a CO2-rich feed by Elnaz Samei; Majid Taghizadeh; Mohsen Bahmani (128-133).
A series of Cu/ZnO-based catalysts were prepared through co-precipitation and alternative pH precipitation methods by adding small amount of colloidal silica (0.6 wt.%) and Mn, Ga and Zr oxides for methanol synthesis from a CO2-rich feed. The prepared catalysts were characterized by a variety of techniques, including X-ray diffraction, N2O chemisorption, temperature programmed reduction, BET and TEM. Catalytic tests were carried out in a fixed bed reactor at 4.5 MPa and 513 K with a mixture of CO/CO2/H2 = 1/1.38/16.5 and GHSV of 15,000 h–1. An accelerated thermally induced deactivation test was performed in the middle of the catalytic performances. During accelerated thermal test and after rising the temperature, an upward trend was observed for space time yield (STY) over the catalysts. The experimental results indicated that a small amount of SiO2 and the oxide additives could significantly improve the catalyst activity and stability.► Cu/ZnO-based catalysts modified with silica and few metal oxides were prepared. ► The interaction between Cu and metal oxides increased the reduction temperature. ► An accelerated thermally induced deactivation test was performed. ► After rising the temperature, an upward trend was observed for STY of methanol. ► Catalyst containing SiO2, Ga2O3 and ZrO2 showed high activity and good stability.
Keywords: Accelerated deactivation test; Cu/ZnO/Al2O3 catalyst; Methanol synthesis; Stability; Activity;
Clay concentration and heating rate effect on crude oil combustion by thermogravimetry by Mustafa Versan Kok (134-139).
In this research, the effect of heating rate and different clay concentrations on heavy oil combustion was investigated by thermogravimetry (TG–DTG). In TG–DTG experiments, two main distinct reaction regions were identified in all of the crude oil + limestone mixtures; known as low temperature oxidation (LTO) and high temperature oxidation (HTO) respectively. It was observed that addition of clay to porous matrix (limestone + heavy oil) significantly affected the thermal characteristics and kinetics of crude oil. It was also observed that heating rate affected the reaction region intervals, peak and burn-out temperatures. Kinetic analysis of the samples was determined and it was observed that activation energies generated for the high temperature oxidation region for crude oil and crude oil/clay mixtures are in the range of 48.5–151 kJmol− 1 at three different heating rates► Three reactions were observed in crude oil combustion in the presence of clay. ► Clay reduced the activation energy of the crude oil samples. ► Clay is one of the potential catalysts for crude oil combustion.
Keywords: Heavy crude oil; Clay; Thermal analysis; Kinetics;
Washability curves for the lower coal seams in Candiota Mine — Brazil by K. Ferreira de Souza; C. Hoffmann Sampaio; J.A. Torriani Kussler (140-149).
In Brazil, the largest coal reserve is located in Candiota Coalfield, in the State of Rio Grande do Sul, currently mined by CRM — Companhia Riograndense de Mineração. The lower coal seams in this coalfield correspond to 30% of the entire coal reserve, but they are not mined. For the purpose of this paper, only the seams I1, I2 and I4 will be discussed. These seams have as yet not been characterized for beneficiation purposes. Therefore, washability curves were generated based on sink-and-float tests to evaluate the main characteristics of such coals for a future gravimetric beneficiation study. From these curves, the average curves were plotted, representing more closely the characteristics of each seam. Based on this, a comparative study was carried out for both selective and simultaneous gravimetric beneficiation of these three seams, without taking into consideration the process efficiency. For an ash content of 42%, the mass theoretical yield obtained was of 33% (selective beneficiation) and 31% (simultaneous beneficiation) for the coarse size fraction, and 76% (selective beneficiation) and 74% (simultaneous beneficiation) for the fine size fraction.► The average washability curves supply the parameters necessary to a gravimetric beneficiation. ► The total sulfur content shows a homogeneous distribution for all seams. ► Both selective and simultaneous beneficiation reduces ash content. ► Seam I4 has potential for power consumption purposes.
Keywords: Coal; Washability curves; Gravimetric beneficiation;
An investigation of the kinetics and mechanism of Fischer–Tropsch synthesis on Fe–Co–Mn supported catalyst by M. Arsalanfar; A.A. Mirzaei; H. Atashi; H.R. Bozorgzadeh; S. Vahid; A. Zare (150-159).
The kinetic of the Fischer–Tropsch synthesis over a Fe–Co–Mn catalyst was investigated in a fixed bed micro reactor. Experimental conditions were varied as follow: reaction pressure 1–10 bar, H2/CO feed ratio of 1–3 and space velocity of 4500 h− 1 at the temperature range of 290–320 °C. 18 models according to the Langmuir–Hinshelwood–Hougen–Watson (LHHW) type rate equation were derived on the basis of detailed set of possible reaction mechanisms, and the reaction rate of this study is fitted fairly well by one kinetic expression based on LHHW mechanism. The kinetic parameters were estimated with non-linear regression method and the activation energy was 82.520 kJ/mol for optimal kinetic model. The catalyst characterization was carried out using different methods including powder X-Ray Diffraction (XRD) and Brunauer–Emmett–Teller (BET) surface area measurements.► We investigate the kinetic and mechanism of the CO hydrogenation on the MgO supported Fe-Co-Mn catalyst. ► This was prepared by co-precipitation procedure. ► 18 models according to the Langmuir-Hinshelwood-Hougen-Watson (LHHW) type rate equation were derived. ► The reaction rate of this study is fitted fairly well by one kinetic expression based on LHHW mechanism. ► The kinetic parameters were estimated with non-linear regression method.
Keywords: Fe–Co–Mn catalyst; Co-precipitation; Fischer–Tropsch synthesis; Kinetic model;
Optimization of methanol steam reforming over a Au/CuO–CeO2 catalyst by statistically designed experiments by Sutarawadee Monyanon; Apanee Luengnaruemitchai; Sangobtip Pongstabodee (160-168).
The catalytic performance for steam reforming of methanol over 5 wt.% Au/CuO–CeO2 catalysts prepared by deposition–precipitation was investigated using a statistical set of experiments in order to optimize the methanol conversion with minimal carbon monoxide (CO) selectivity. The operating temperature, steam to methanol (S/M) ratio, liquid feed rate and the catalyst weight to He flow rate (W/F) ratio, were evaluated with a full 24 factorial design experimental matrix with four central points. The liquid feed rate displayed a much greater influence on the response, masking the importance of the other factors. At a fixed low liquid feed rate, only the operating temperature had a significant influence on the methanol conversion, whilst this plus the S/M ratio and their interaction influenced the CO selectivity. A central composite rotatable design was then used to approximate the optimal conditions by simultaneously considering the methanol conversion and CO selectivity. The optimum theoretical conditions were found to lie within an operating temperature of ~ 295 °C to ~ 307 °C and an S/M ratio of ~ 1.82 to 2.00 (at a liquid feed rate of 1 cm3 h− 1 and a W/F ratio of 0.17 g s cm− 3), in close agreement with the experimental results.Region (in the shade portion) of the maximal methanol conversion (▪) with the minimal CO selectivity (▪) for SRM over 5 wt.% Au/CuO–CeO2 catalyst.Display Omitted► 5 wt.% Au/CuO–CeO2 catalyst for steam reforming of methanol (SRM). ► A full 24 factorial design experimental matrix with four central points. ► The liquid feed rate masked the importance of the other factors. ► A central composite rotatable design within the response surface method. ► Complete methanol conversion with a minimal CO selectivity.
Keywords: Full factorial design; CCRD response surface; Optimization; Methanol steam reforming;
Combustion characteristics of sodium-free pyrolytic char from hazelnut shell by H. Haykiri-Acma; S. Yaman; S. Kucukbayrak (169-174).
Hazelnut shell is a woody biomass with high sodium content that leads severe fouling problems in combustion systems. Thus, hazelnut shells were pyrolysed under nitrogen to eliminate sodium, and then the burning characteristics of the obtained sodium-free pyrolytic char were investigated up to 900 °C by non-isothermal thermogravimetry. Inorganic and the morphological properties of original biomass and the char were investigated via Inductively Coupled Plasma (ICP) and Scanning Electron Microscopy (SEM) techniques. Also, inorganic phases in the pyrolytic char were determined by X-Ray Diffractometry (XRD). The pyrolytic chars were burned up to 900 °C by heating rates of 5, 10, 20, 30, 40, and 50 °C/min under dry air flow. It was found that the pyrolysis process almost eliminated sodium, and a sodium-free char that has higher calorific value compared to the parent biomass was obtained. The reactivity of the char during combustion did not show any decrease as conversion proceeds. It was also found that char burning reactivity was higher at low heating rate conditions. Also heating rate has an influence on burning of char in such a way that the increasing heating rate shifted the temperatures of maximum burning rates to higher temperatures.► Alternative study to mitigate problems of sodium in biomass. ► We produced sodium-free char from high sodium content hazelnut shell. ► We found that the reactivity of char during combustion did not decrease as conversion increased. ► It was also found that char burning reactivity was higher at low heating rate conditions.
Keywords: Biomass; Hazelnut shell; Thermogravimetry; Combustion; Heating rate;
A kinetic model for the oxidative coupling of methane over Na2WO4/Mn/SiO2 by Mi Ran Lee; Myung-June Park; Wonjin Jeon; Jae-Wook Choi; Young-Woong Suh; Dong Jin Suh (175-182).
A kinetic model of the oxidative coupling of methane was developed by considering ethane, ethylene, carbon monoxide, and carbon dioxide production in such a way that the reactor was designed for the reactions to take place in the catalyst-loading region as much as possible. The effectiveness of the reactor specification was validated by low conversion of methane in the blank test. A mechanism for catalytic reactions on the surface of Na2WO4/Mn/SiO2 gel and gas-phase radical reactions was suggested based on a literature survey. Reaction rates were developed by applying rapid equilibrium for adsorption and the quasi steady state approximation to the intermediate on the catalytic surface. Kinetic parameters were estimated by fitting experimental data with temperature, space velocity, and CH4/O2 ratio varied in full factorial manner. The validity of the model was corroborated by comparing its simulated results with experimental data. The effectiveness of the estimated parameters was discussed with respect to reported values. The effects of operating conditions were assessed using the developed model.► Oxidative coupling of methane (OCM). ► Kinetic model based on the detailed mechanism. ► Mathematical modeling and parameter estimation. ► Effects of operating conditions.
Keywords: Oxidative coupling; Methane; Na2WO4/Mn/SiO2 gel; Kinetic model; Parameter estimation;
Clay minerals in nonaqueous extraction of bitumen from Alberta oil sands by Ali Hooshiar; Peter Uhlik; Douglas G. Ivey; Qi Liu; Thomas H. Etsell (183-194).
Although not used commercially, a nonaqueous extraction process is of great interest to extract bitumen from the Alberta oil sands due to its potential advantages, such as high bitumen recovery even from low grade oil sands ores and the elimination of slow settling, sludge tailings ponds with stable suspensions. While clay minerals have been characterized in water-based bitumen extraction from the oil sands to some extent, the gap of knowledge in the characterization of clay minerals in a nonaqueous bitumen extraction process has led to the current research. Two Syncrude oil sands ores, a high grade, low fines, good processing ore and a mid grade, high fines, poor processing ore, were used in the nonaqueous bitumen extraction. The raw oil sands ores, products of the extraction (supernatant) and the tailings generated from the extraction were investigated by low-pressure scanning electron microscopy (SEM). These observations showed some important differences between the two ore samples in terms of the settling behavior of the solids after nonaqueous extraction. In addition, the clay size fractions (< 2 μm) of the oil sands ores and supernatants were analyzed by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) after removing the organic matter. Kaolinite and illite were found to be the dominant clay minerals based on XRD analysis. Quantitative XRD analysis revealed an enrichment of kaolinite in the supernatant when compared with the ore. HRTEM studies showed the presence of monolayer smectitic clay minerals in clay fraction of ore and supernatant while these Monolayers were not detectable by XRD.
Keywords: Clay minerals; Oil sands; SEM; HRTEM; Nonaqueous extraction; XRD;
A comparison study of mesoporous Mo/H-ZSM-5 and conventional Mo/H-ZSM-5 catalysts in methane non-oxidative aromatization by Heng Liu; Shuang Yang; Jing Hu; Fanpeng Shang; Zhifang Li; Chen Xu; Jingqi Guan; Qiubin Kan (195-202).
The mesoporous ZSM-5-S and ZSM-5-M samples were synthesized by using ordered mesoporous carbon (CMK-3) and disordered carbon rods (C-MCM-41) as the hard template, respectively, and for comparison, conventional ZSM-5-C was also synthesized with the same synthesis composition and procedure except for the presence of carbon template. The mesoporous ZSM-5 samples exhibited similar geometrical shape, but different pore properties than the conventional ZSM-5. Moreover, Mo-modified catalysts, Mo-ZSM-5-C, Mo-ZSM-5-S and Mo-ZSM-5-M, were prepared for the non-oxidative aromatization of methane. The physical properties and acidities of the samples were characterized by XRD, SEM, TEM, BET and IR spectroscopy. Compared with Mo-ZSM-5-C, the Mo-ZSM-5-S and Mo-ZSM-5-M catalysts showed similar conversions of methane, but higher yields of aromatics. In addition, Mo-ZSM-5-S and Mo-ZSM-5-M were more stable than Mo-ZSM-5-C. The exceptional catalytic behavior of Mo-modified mesoporous ZSM-5 catalysts may be attributed to the generation of secondary mesoporous systems within the zeolite crystal, which may lead to easier access to the active sites for reactants and be favorable for the diffusion of larger molecule product formed in the microporous channels during the methane aromatization reaction.
Keywords: Mesoporous ZSM-5; Mesoporous carbon; Methane dehydroaromatization; Molybdenum;
Co-pyrolysis of oil shale and High density polyethylene: Structural characterization of the oil by A. Aboulkas; T. Makayssi; L. Bilali; K. El harfi; M. Nadifiyine; M. Benchanaa (203-208).
This study describes a detailed characterization of the oil obtained by co-pyrolysis of Tarfaya oil shale (Morocco) and high density polyethylene (HDPE) and by pyrolysis of oil shale and HDPE individually. The oil (obtained under the most suitable conditions, temperature of 500–525 °C and heating rate of 10 °C/min) was characterised by elemental analysis, nuclear magnetic resonance spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FTIR). In addition, column chromatography was used group composition of oil was determined. Gas chromatography was achieved on n-hexane fractions. Adding HDPE to the oil shale results in increased oil yields, which indicates synergetic effect between the oil shale and HDPE. The addition of HDPE to oil shale improved fuel properties of shale oil leading to a decrease in the oxygen content of shale oil. The results show that the oil obtained by co-pyrolysis has similar properties with commercial gasoline. HDPE acts as a hydrogenation medium for the oil shale product as revealed by FTIR results.► The oil obtained by co-pyrolysis of oil shale and high density polyethylene under the most suitable conditions (temperature of 500–525 °C and heating rate of 10 °C/min) shows similar properties with commercial gasoline. ► Adding the HDPE to the oil shale results in increased oil yields, which indicate synergetic effect between the oil shale and HDPE. The addition of HDPE to oil shale improved fuel properties of shale oil leading to a decrease in the oxygen content of shale oil. ► HDPE acts as a hydrogenation medium for the oil shale product as revealed by FTIR results.
Keywords: Oil shale; Polyethylene; Co-pyrolysis; Oil characterization;
Co-pyrolysis of oil shale and plastics: Influence of pyrolysis parameters on the product yields by A. Aboulkas; T. Makayssi; L. Bilali; K. El harfi; M. Nadifiyine; M. Benchanaa (209-213).
In this study, co-pyrolysis of oil shale with plastic wastes was investigated with the aim to study the product distribution and to identify optimum process conditions for maximizing the oil yield. Experiments were performed in stainless steel autoclave under nitrogen atmosphere. The effects of pyrolysis temperature, heating rate and plastic type on the yields of the products were investigated. Pyrolysis runs were performed using pyrolysis temperatures between 400 and 600 °C with heating rates of 2 to 20 °C/min. Three plastics: high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP) were individually co-pyrolyzed with Moroccan oil shale. The results showed that increase the pyrolysis bed temperature from 400 to 500–525 °C resulted in a significant increase in the oil yield, after which temperature the oil yield decreased. It was also observed for both oil shale and oil shale/plastic mixtures that the oil yield was increased as the heating rate was increased from 2 to 10 °C min− 1. Increasing the heating rate up to 20 °C min− 1 caused a slight reduction in the oil yield. The highest oil yield was obtained between 500 and 525 °C pyrolysis temperature with a heating rate of 10 °C min− 1. Existence of interactions between constituents is proved by comparing the result of experimental total conversion and products yields with rationally calculated yields of pure oil shale and polymers from pyrolysis process. The difference between the experimental and calculated values was positive, indicating that co-pyrolysis of the two materials enhanced the chemical reactivity during pyrolysis and produced a higher conversion than that from individual oil shale.► Co-pyrolysis of oil shale with plastic wastes was investigated with the aim to identify optimum process conditions. ► The effects of pyrolysis temperature, heating rate and plastic type were investigated. ► The highest oil yield was obtained between 500 and 525 °C with 10 °C min–1. ► The difference between the experimental and calculated values was positive.
Keywords: Oil shale; Polyethylene; Polypropylene; Co-pyrolysis; Pyrolysis parameters;
Continuous production of biodiesel from vegetable oil using supercritical ethanol/carbon dioxide mixtures by Aline Santana; José Maçaira; M. Angeles Larrayoz (214-219).
Biodiesel production is worthy of continued study and optimization of production procedures because of its environmentally beneficial attributes and its renewable nature. Transesterification of triglycerides using supercritical ethanol on ion-exchange resin catalyst was investigated to study the ethyl ester conversion process. The reaction parameters investigated were the reaction time, pressure, temperature and molar ratio (alcohol to triglycerides), and their effect on the biodiesel formation. Addition of a co-solvent, supercritical carbon dioxide (critical point at 31 °C and 7.3 MPa), decreased the operating conditions maintaining a high reaction rate. The mixture ethanol/carbon dioxide used in this work was 1:3 molar ratio. The experiments were conducted at temperatures of 150–200 °C, pressure from 150 to 250 bar and reaction times from 2 to 10 min, and molar ratios of ethanol to vegetable oil from 20 to 45. The evolution of the process was followed by gas chromatography, determining the concentration of the ethyl esters at different reaction times. Results showed that ethyl esters obtained in the continuous fixed bed reactor under supercritical conditions can achieve 80% yield of biodiesel at reaction time of 4 min.
Keywords: Biodiesel; Transesterification; Supercritical fluids; Ethyl ester; Solid acid catalyst;
Effect of zinc addition on catalytic properties of PtSnK/γ-Al2O3 catalyst for isobutane dehydrogenation by Yiwei Zhang; Yuming Zhou; Junjun Shi; Xiaoli Sheng; Yongzheng Duan; Shijian Zhou; Zewu Zhang (220-227).
The effect of zinc addition on the catalytic properties of PtSnK/γ-Al2O3 catalyst for isobutane dehydrogenation has been investigated by reaction tests and some physicochemical characterizations such as nitrogen adsorption, H2 chemisorption, H2–TPD, NH3–TPD, TPR, TEM and TPO. It was found that suitable addition of Zn (0.2 and 0.4 wt.%) to PtSnK/γ-Al2O3 catalyst could not only increase the platinum dispersion by geometric effect, but also decrease the carbon depositions. In these cases, the presence of zinc strengthened the interactions between Sn species and the support, thus inhibiting the reduction of Sn species. Among the catalysts studied, the PtSnKZn(0.4%)/Al catalyst exhibited the best performance in terms of isobutane conversion and stability. However, when the content of Zn was excessive, the interfacial character between metal and support, and the character of Pt metal had been changed. The formation of PtZn alloy resulted in the loss of catalytic activity and stability, while had a promoting effect for the reaction selectivity.► The presence of Zn improves the platinum dispersion by geometric effect. ► Zinc strengthens the interactions between Sn species and the support. ► Excessive content of Zn changes the character of Pt and the interfacial properties. ► The addition of 0.4 wt.% Zn results in the best catalytic performances.
Keywords: Zinc; Isobutane dehydrogenation; Isobutene; Catalyst;
Preparation of composite TiO2–Al2O3 supported nickel phosphide hydrotreating catalysts and catalytic activity for hydrodesulfurization of dibenzothiophene by Hua Song; Min Dai; Yun-Tao Guo; Yong-Jiang Zhang (228-236).
Composite TiO2–Al2O3 supports were prepared by the sol–gel methods, and a series of Ni–P hydrotreating catalysts supported on TiO2–Al2O3 supports were prepared by impregnation of nickel phosphate precursors followed by reduction in hydrogen at 973 K. The catalysts were characterized by X-ray diffraction (XRD), N2-adsorption specific surface area measurements (BET), transmission electron microscope (TEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetry differential thermal analysis (TG-DTA). The effect of Ti/Al molar ratio and initial Ni/P molar ratio on catalyst structure as well as HDS performance was studied. The results indicated that the TiO2 can inhibit the formation of AlPO4, and act as an electronic promoter for the Ni–P catalyst. When the initial Ni/P molar ratio is lower than 1/1, the main phase obtained is Ni2P. The Ni2P/TiO2–Al2O3 catalyst prepared with initial Ni/P ratios of 1/1 and Ti/Al molar ratio of 1/1.6 exhibited the highest activity. At a reaction temperature of 606 K, a pressure of 3.0 MPa, a H2/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 2.0 h− 1, the HDS conversion reached 96.00%.Display Omitted
Keywords: Nickel phosphide; Hydrodesulfurization; Composite TiO2-Al2O3; Dibenzothiophene;
Review of the effects of biodiesel on NOx emissions by S. Kent Hoekman; Curtis Robbins (237-249).
Compared to conventional diesel fuel, use of biodiesel is generally found to reduce emissions of hydrocarbons (HC), carbon monoxide (CO), and particulate matter (PM); but to increase oxides of nitrogen (NOx) emissions. This paper reviews and summarizes relevant literature regarding the so-called “biodiesel NOx effect, and presents theories” to explain this effect. In modern diesel engines, several factors related to fuel composition and engine control strategies are important, though no single theory provides an adequate explanation of the biodiesel NOx effect under all conditions. There is evidence to suggest that effects on injection timing, ignition delay, adiabatic flame temperature, radiative heat loss, and other combustion phenomena all play some role. The biodiesel NOx effect can be mitigated by modifying engine control settings — particularly by retarding injection timing and increasing exhaust gas recirculation (EGR). The absolute magnitude of the biodiesel NOx effect appears to be reduced with modern engines, although there are cases where the percentage change is still substantial. Sophisticated after-treatment systems required to achieve the 2010 diesel engine emissions standards do not appear to be significantly affected by use of biodiesel. However, longer term study is warranted, as such systems have only been in commercial use for a short time.► Use of biodiesel usually, but not always, increases NOx exhaust emissions. ► Fuel composition, engine technology and operating conditions all affect NOx. ► The biodiesel NOx effect can be mitigated by changes in engine operation parameters.
Keywords: Biodiesel; NOx; Emissions; FAME;
A pilot-scale investigation of ash and deposition formation during oil-palm empty-fruit-bunch (EFB) combustion by T. Madhiyanon; P. Sathitruangsak; S. Sungworagarn; S. Pipatmanomai; S. Tia (250-264).
In Thailand, oil-palm empty-fruit-bunch (EFB) a by-product of the crude-palm-oil milling process is currently one of the most promising potential energy resources. However, the ash-forming potassium, chlorine, silicon, and calcium constituents of EFB fuel can cause severe fouling, slagging, and ash meltdown, during combustion. This study is aimed to investigate EFB firing in a pilot-scale reciprocating grate-fired combustor with a 150 kWth capacity. The study included chemical analyses of fuel and fuel ash, and samples of bottom ash, fly ash, and deposits derived from laboratory combustion tests. Experiments were conducted at temperatures of ≈ 800 °C (low-temperature) and 900–950 °C (high-temperature).Deposits mainly formed on the upstream side of the probe, and comprised two distinct layers, i.e., a thin white inner layer, and a gray outer layer. A swift growth of deposits on the cooled deposit probe, simulating superheater conditions, was evident, with significant retardation of heat transfer. Heat uptake by the probe appeared to reduce to 70% of the initial value within a 19-h period. The deposit mass flux was 167 g/m2 h, which corresponded with a fouling thermal resistance of 0.023 m2·K/W. Following initial deposit formation of KCl condensate, particle impaction entailed deposit formation for incorporating Si- and Ca-rich fly ash particles into the deposits. XRF (X-ray fluorescence spectrometer) and SEM/EDX (scanning electron microscopy/energy dispersive X-ray) analyses revealed that not only did KCl mainly exist in the inner deposit layer, but also dominated the entire deposit mass (60–80 wt.%), suggesting a crucial role for alkali condensation in deposit formation. If the bulk flue gases were sufficiently cooled, the KCl deposited on the probe by the transport of small solidified KCl particles. Corrosion attack was apparent near the metal surface and involved the deposition of KCl. SEM–EDX mapping exhibited that silica in combination with potassium led to the formation of low-melting-point compounds, which readily melted at high-temperature combustion. ICP-AES (inductively coupled plasma-atomic emission spectroscopy) analysis indicated that the potassium in the deposits had high mobility; the results were consistent with the XRF and SEM–EDX analyses.► Heat uptake by the probe had declined to 70% of its initial value within 19 hours. ► Fouling resistance value was found to be 0.023 m2K/W, and deposit flux was 167 g/m2h. ► Deposits comprised a thin white inner layer, and a gray outer layer. ► Much of potassium in the deposits was found to be water-soluble.
Keywords: Biomass; Deposits; Grate-fired combustor; Potassium chloride; Slagging;
Thermal degradation of acrylonitrile–butadiene–styrene (ABS) containing flame retardants using a fluidized bed reactor: The effects of Ca-based additives on halogen removal by Su-Hwa Jung; Seon-Jin Kim; Joo-Sik Kim (265-270).
In this study, the thermal degradation of a waste fraction of acrylonitrile–butadiene–styrene containing brominated flame retardants was performed to reduce halogen content in the pyrolysis oil. Thermal degradation was completed using Ca-based additives (calcium oxide, calcium hydroxide and oyster shells) in a bench-scale pyrolysis plant equipped with a fluidized bed reactor and char separation system. Pyrolysis was carried out in a temperature range of 430–510 °C. In the absence of any additive, the oil yield amounted to about 77 wt.%. With the additives, the oil yield was markedly reduced to within a range of 45–64 wt.%. The principle compounds in the oils were toluene, ethylbenzene, styrene, cumene, α-methylstyrene, phenol and heteroatom-containing compounds. When Ca(OH)2 was applied, total bromine and chlorine contents in the oil decreased to 0.05 and 0.04 wt.%, respectively. In addition, Ca(OH)2 reduced the antimony content in the oil to below 0.001 ppm. Most of the halogens and antimony in the feed material were present in the char obtained after pyrolysis.► It gives results on the pyrolysis of ABS-Br in a fluidized bed reactor. ► Application of Ca-based additives including oyster shells for halogen removal. ► Ca-based additives have also an influence on the oil composition.
Keywords: Pyrolysis; Fluidized bed; Flame-retardant; Dehalogenation; Additives;