Fermentation technology to improve productivity in dry grind corn process for bioethanol production Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-20 Deepak Kumar, Ankita Juneja, Vijay Singh
High solid fermentation during bioethanol production is a promising process engineering strategy to reduce total energy use and water requirements, and to improve productivity. However, ethanol toxicity at higher concentrations restricts the corn solids to 30–32% (w/w) during dry grind corn ethanol process. This work, using in situ ethanol removal, results in two big improvements in the fermentation process: 1) achieve complete fermentation of high solids slurries (up to 42%) at typical commercial enzyme dosages, and 2) fasten the fermentation process for currently used process with 32% solids. Application of vacuum at optimal times during fermentation (1 h at 12, 24, 36, and 48 h) of 40% corn solids resulted in complete fermentation, compared to about 12% residual glucose in the conventional process. The ethanol yield of 0.42 L/kg of dry corn with about 80% ethanol conversion efficiency was 88% higher than that of the conventional process at 42% solids (0.22 L/kg dry corn). Application of 1.5 h of vacuum at 18 and 24 h of fermentation with 32% solids resulted in high fermentation rates and decreased the fermentation time by more than 50%. Shorter fermentation times can allow processing of more material with the same equipment and allow smaller fermentation tanks in new plants, which would lead to both, lower capital and operating cost.
Effect of electrochemical conversion of biofuels using ionization system on CO2 emission mitigation in CI engine along with post-combustion system Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-13 Thiyagarajan Subramanian, Edwin Geo Varuvel, Jesu Martin Leenus, Nagalingam Beddhannan
Global warming caused by greenhouse gas emission is a major threat in recent times. Carbon dioxide (CO2) is a major source of greenhouse gas emission from CI engine. The present study aims to investigate the effect of pre-combustion, oxygenate and post-combustion system with biofuel blends in single cylinder CI engine on CO2 emission. All the experiments were conducted in a single cylinder CI engine with 5.2 kW rated power at 1500 rpm at 50% and 100% load. Diesel is replaced with Karanja oil methyl ester (KOME) and both are taken as baseline data. Low carbon biofuel namely orange oil (ORG) was blended on an equal volume basis with KOME and tested. Zeolite based post-combustion capture system (ZPCS) and fuel ionization filter (FIF) as pre-combustion capture system was tested along with 20% methanol (M) blend with KOME-ORG. FIF electrochemically ionizes the fuel molecules and aids in quick dispersion of the ions for improved combustion. Hydrocarbon based biofuels are converted to carbon, hydrogen and oxygen ions, where hydrogen takes part in combustion and oxygen enhances the combustion process. At 100% load, CO2 emission for KOME-ORG + M20 + FIF + ZPCS is 68% less compared to KOME. The combination also reduces NO and smoke by 48% and 51% compared to KOME at 100% load. The combined effect of FIF, ZPCS and methanol aided in the simultaneous reduction of NO, smoke and CO2 emission.
Evolution of the metal and metalloid content along the bioethanol production process Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-12 Carlos Sánchez, Jean-Paul Vidal, Charles-Philippe Lienemann, Jose-Luis Todolí
Effect of iron ore type on the thermal behaviour and kinetics of coal-iron ore briquettes during coking Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-12 Runsheng Xu, Bowen Dai, Wei Wang, Johannes Schenk, Zhengliang Xue
Effect of three iron ore types (limonite, hematite and oolitic hematite) on the thermal behaviour and reaction kinetics of coal-iron ore briquettes during coking was investigated using the thermal analysis method. The carbonized briquettes were characterized using the XRD and SEM. The results showed that all three iron ores were completely reduced to Fe at the final coking stage. The addition of iron ore to the coal briquette had little influence on the gas yield, but could significantly affect the reaction rate. A synergistic effect of iron ore and coal occurred in the later reaction stage, and the initial temperature of the synergistic effect varied with the type of iron ore in coal-iron ore briquettes. The type of iron ore hardly affected the devolatilization rate of coal-iron ore briquettes, but could greatly influence the reduction rate of iron ore, subsequently the gasification rate of coal char. In addition, the better reduction ability of iron ore could more easily lead to the cracking of coke. When the iron ore was blended into the coal briquette, the reaction kinetics at the first and third reaction stage changed. The three coal-iron ore briquettes had similar weighted average apparent activation energies of 30.67–35.52 kJ/mol.
CO2 absorption and diffusion in ionic liquid [P66614][Triz] modified molecular sieves SBA-15 with various pore lengths Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-09 Jun Cheng, Yannan Li, Leiqing Hu, Jianzhong Liu, Junhu Zhou, Kefa Cen
Mesoporous molecular sieves SBA-15 with four pore structures were loaded with an ionic liquid [P66614][Triz] to adsorb CO2 from raw biohythane. The hybrid sorbents of SBA-15 loaded with [P66614][Triz] were characterized by using N2 adsorption analyzer, thermogravimetric analyzer, scanning electron microscopy, and high-resolution transmission electron microscopy. The molecular sieve SBA-15 (with the most probable pore size of 4.3 nm) loaded with 50% ionic liquid (IL), which was called SBA-15 (4.3) − 50% IL, exhibited the fastest CO2 absorption rate and the shortest equilibrium time, which was approximately one-third of the equilibrium times of the other three hybrid sorbents. An intraparticle diffusion model was used to clarify that SBA-15 (4.3) − 50% IL (with the shortest pore length of 120 nm) executed a two-stage CO2 absorption process, which reduced the CO2 absorption time. The rate constant kI in the first stage of the CO2 absorption of SBA-15 (4.3) − 50% IL was approximately four times as much as those of the other three hybrid sorbents because the cross-section area of its total pores was approximately three times higher than those of the other three hybrid sorbents. Results showed that pore length had significant effect on CO2 absorption performance.
An X-ray photoelectron spectroscopic perspective for the evolution of O-containing structures in char during gasification Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-06 Shuai Wang, Liping Wu, Xun Hu, Lei Zhang, Kane M. O'Donnell, Craig E. Buckley, Chun-Zhu Li
The purpose of this study is to investigate the evolution of O-containing structures of char during gasification. Mallee wood (4.75–5.60 mm) from Western Australia was gasified in a fluidised-bed reactor at 600–900 °C in O-containing (pure CO2, 15% H2O-Ar) and non-O-containing atmospheres (15% H2-Ar). X-ray photoelectron spectroscopy (XPS) was applied to obtain detailed information about the nature of oxygen bonding with carbon as well as the content of oxygen species in char. The similar O/C ratio of char from XPS and elemental analysis indicated the relative chemical uniformity between char surface and char matrix. The deconvolution results of the O 1s spectra showed that the reactivity of the inherent aromatic C O structure was much higher than that of the aromatic C O structure during gasification. The amount of aromatic C O structure left in char during gasification in non-O-containing atmosphere was lower than that in O-containing atmosphere while the consumption of aromatic C O structure was proportional to the progress of gasification, regardless of the atmosphere. The newly formed C O structure in char during the gasification in the O-containing atmosphere was likely to be responsible for the high gasification reactivity. The well-dispersed alkali earth metallic species could be carbonated to form CaCO3 and MgCO3 on char surface once the char was exposed to CO2 at 900 °C.
Investigation of colony disruption for hydrocarbon extraction from Botryococcus braunii Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-04 Shun Tsutsumi, Yasuhiro Saito, Yohsuke Matsushita, Hideyuki Aoki
Botryococcus braunii is a colonial microalga that produces hydrocarbons. While the microalga stores almost all the amount of hydrocarbons in its colony matrix, the amount of the extracted hydrocarbon without any pretreatment is typically very small. We performed mechanical cell disruption using a JET PASTER® and a bead mill as the pretreatment ways to facilitate hydrocarbon extraction from B. braunii. After the disruption, the size and shape of colonies changed. In the JET PASTER treatment at 4800 rpm, the concentration of removed polysaccharides increased 146 to 173 μg/mL and the hydrocarbon yield increased 2.7 to 82.8%. In the bead mill treatment, the concentration of removed polysaccharides increased 146 to 210 μg/mL and hydrocarbon yield increased 2.7 to 42.3%. Therefore, the disruption of colonies and polysaccharides around algal colonies would affect the hydrocarbon extraction. In addition, the apparent photosynthetic activity of the sample treated by the JET PASTER was 0.71 that is almost the same value as that of the untreated sample, whereas that of the sample treated by the bead mill was 0.64. Therefore, the JET PASTER treatment did not affect the photosynthetic function of B. braunii.
Ultrasonic technique for online measurement of bulk density of stamp charge coal cakes in coke plants Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-04 Shivanandan Indimath, Rajendran Shunmugasundaram, Srinivasagan Balamurugan, Bidyut Das, Ranjan Singh, Monojit Dutta
Coke oven batteries utilize stamp charged coal cakes for production of high quality blast furnace coke. Crushed coal blends are mechanically stamped to produce coal cakes. It is crucial to have a good control over this stamping operation so as to achieve a uniform bulk density (≈ 1100–1200 kg·m− 3 wet basis) of coal cake post stamping. This can facilitate robust and energy efficient coking operation. The dynamic nature of the stamping operation necessitates an online bulk density measurement technique. An ultrasonic technique which enables online measurement of bulk density during the stamping operation is described. The ultrasonic response was found to have a straight line correlation with bulk density (wet basis) and moisture content of stamped coal with an R2 value of 0.98. The effect of moisture content in the coal on the ultrasonic measurements is also discussed. A lab scale prototype was developed with integrated sensors to emulate online measurement. The prototype was found to have a measurement error of less than ± 1.6%. This method can also be suitably adapted for online bulk density measurement of granular solids other than crushed coal.
Chemical looping combustion of biomass: CLOU experiments with a Cu-Mn mixed oxide Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-04 Iñaki Adánez-Rubio, Antón Pérez-Astray, Teresa Mendiara, María Teresa Izquierdo, Alberto Abad, Pilar Gayán, Luis F. de Diego, Francisco García-Labiano, Juan Adánez
Chemical looping combustion (CLC) is a low-cost CO2 capture technology with a low energy penalty. Bio-energy with CO2 capture and storage (BECCS) opens up the possibility for negative CO2 emissions involving the removal of CO2 already emitted into the atmosphere. The oxygen needed for combustion in CLC processes is supplied by a solid oxygen carrier circulating between the fuel reactor and the air reactor. In this work, the combustion of different types of biomass, such as pine sawdust, olive stones and almond shells, was studied in a continuous 1.5 kWth CLC unit. A mixed Cu-Mn oxide was used as the oxygen carrier. This material releases gaseous oxygen when reduced, resulting in Chemical looping combustion with oxygen uncoupling (CLOU). The released oxygen reacts with both the volatiles and char generated inside the fuel reactor when biomass is fed into it. The oxygen carrier is reoxidized in air inside the air reactor. High CO2 capture and 100% combustion efficiencies were achieved with this Cu-Mn oxygen carrier. The oxygen concentration inside the air reactor did not affect CO2 capture efficiency under the studied conditions.
NO reduction by different tar agents and model compounds in a drop-tube reactor Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-04 Yutthasin Bunman, Hai-Sam Do, Xi Zeng, Zhennan Han, Shiqiu Gao, Guangwen Xu
Our previous studies suggested that the biomass tar derived from pyrolysis of distilled spirit lees (DSL) is an attractive agent for lowering NOx emission in the circulating fluidized bed decoupling combustion (CFBDC) process. The present work is furthered to evaluate the capabilities of other tar agents including sawdust (SD) tar and Xianfeng (XF) coal tar for NO reduction in a lab-scale drop-tube reactor. Additionally, five representative model tar compounds including phenol, benzene, acetic acid, methyl acetate and heptane were also tested to clarify the contribution of the main components in tar agents to NO reduction. The realized NO reduction efficiency by tar obviously varied with the reburning stoichiometric ratio (SR) and reaction temperature. At a specified mass feeding rate of reductant, say 0.15 g/min, the NO reduction realized by the SD tar is higher than that by the XF coal tar, and was even better than that by the DSL tar obtained in our previous study. Testing the NO reduction by model tar compounds revealed that phenol plays an important role in enabling its good NO reduction for the SD tar. The major understanding from the work is that the compounds containing at least an aromatic ring (e.g. phenol, benzene, etc.) are the major contributor for reducing NO in either biomass tar or coal tar.
Numerical analysis of methane pyrolysis in thermal plasma for selective synthesis of acetylene Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-05 Hang An, Yan Cheng, Tianyang Li, Yue Li, Yi Cheng
Thermal plasma pyrolysis can realize direct synthesis of acetylene and carbon black from methane, while the yields of products vary according to the reaction conditions. In the present work, a pre-proposed detailed kinetic mechanism is applied to investigate the efficiency and product distribution of methane pyrolysis in thermal plasma. The kinetic mechanism is validated with experiments, which proves the reliability of the mechanism under the conditions of thermal plasma. From simulation results, higher temperature and residence time in millisecond are beneficial for higher acetylene yield, while long residence time is beneficial for the production of carbon black. To be specific, when the temperature is higher than 2100 K, conversion of methane is above 99 wt% and the yield of acetylene is above 80 wt%, which is referred to as the selective synthesis of acetylene from methane. When temperature increases, the proper residence time for the maximum acetylene yield would decrease to within one millisecond.
Effects of hydrothermal upgrading on the physicochemical structure and gasification characteristics of Zhundong coal Fuel Process. Technol. (IF 3.752) Pub Date : 2018-01-05 Xiao-Pei Zhang, Cheng Zhang, Peng Tan, Xin Li, Qing-Yan Fang, Gang Chen
It is difficult to directly use Zhundong (ZD) coal because of its high alkali metal content and the associated slagging and fouling problems. Therefore, in this study, hydrothermal (HT) treatment was introduced to remove the alkali metals and upgrade ZD coal at 150–350 °C. The physicochemical structure and gasification characteristics of ZD coal were investigated. The results showed that the properties of the upgraded coal were effectively improved and the coal rank increased after HT upgrading. Additionally, alkali metals Na and K were notably removed, reaching approximately 98% and 82% at 350 °C, respectively. BET analysis indicated that the pore structure was initially enriched at 150–300 °C and then deteriorated at 300–350 °C. The XRD and Raman results revealed that the microcrystalline structure tended to be more aromatic and graphitized, and the chemical structure became dense, orderly and stable. In addition, the CO2 gasification reaction curve shifted to the high-temperature region as the HT temperature increased. The gasification reactivity exhibited a decreasing trend, and the results were verified by dynamic analysis. Moreover, the comprehensive influence of different factors on the gasification reactivity was explored via a potential mechanism analysis, and a multiple linear regression model of gasification reactivity was established.
The influence of swirling flows on pulverized coal gasifiers using the comprehensive gasification model Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-28 Jianliang Xu, Qinfeng Liang, Zhenghua Dai, Haifeng Liu
The burner swirl intensity plays an important role in membrane wall safety and the gasification performance of pulverized coal, swirl gasifiers. The comprehensive gasification model (CGM), having two reaction regions and one radial heat transfer region, was used to simulate the influence of the swirl number (SN) on gasification performance, multiphase flow, reactions in the space, and reactions regarding the membrane wall. The results show that an SN of 0.66 is a critical point to divide low-swirl and high-swirl flows for the single-swirl-burner gasifiers of this study. Gasifier performance increases sharply with increased SN for low-swirl burners, whereas SN has little influence on gasifier performance (and multiphase flow) for high-swirl cases. In this paper, we examine the relationship between burner swirl and flow fields, temperature distributions in the space and on membrane wall, slag thickness, and the molten slag velocity distribution on the membrane wall. The influence of SN on these parameters is more remarkable at the top of the reattachment point than below it. The slag layer formed on the membrane wall isolates high-temperature gas effectively, except around the reattachment point. To guarantee gasifier performance and membrane wall safety, the burner SN should be between 0.66 and 0.9 for the single-swirl-burner gasifiers of this study.
Preparation of synthetic graphite from bituminous coal as anode materials for high performance lithium-ion batteries Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-29 Baolin Xing, Chuantao Zhang, Yijun Cao, Guangxu Huang, Quanrun Liu, Chuanxiang Zhang, Zhengfei Chen, Guiyun Yi, Lunjian Chen, Jianglong Yu
An earth-abundant and low cost bituminous coal was used as precursor to prepare synthetic graphite materials through preliminary carbonization coupled with further high temperature graphitization treatment at 2000–2800 °C. The microstructure characteristics of the obtained synthetic graphite materials were characterized by means of X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectroscopy and nitrogen adsorption–desorption. The results show that the microstructures of synthetic graphite materials are strongly dependent on the graphitization temperature. The synthetic graphite graphitized at 2800 °C has perfect ordered layered structure with high graphitization degree and relatively large surface area with well-developed mesopores, which offers a favorable pathway for the electrochemical intercalation-deintercalation of lithium ions in carbon matrix. Such synthetic graphite applied as anode materials for lithium-ion batteries presents a maximum reversible capacity of 310.3 mAh·g− 1 at current rate of 0.1C and still remains as high as 143.9 mAh·g− 1 at current rate of 5C. Moreover, the synthetic graphite also exhibits superior rate capability and outstanding cycling performance with over 95.3% initial capacity retention after 100 cycles. This study demonstrates a promising feasibility for large-scale production of synthetic graphite materials from bituminous coal for high performance lithium-ion batteries.
Transformations of n-undecane–indole model mixtures over the cracking catalysts resistant to nitrogen compounds Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-29 T.V. Bobkova, O.V. Potapenko, V.P. Doronin, T.P. Sorokina
Additives to a zeolite-containing cracking catalyst were synthesized and studied in order to enhance the resistance to the poisoning effect of nitrogen compounds (in particular indole) upon cracking of n-undecane as the model FCC hydrocarbon. The additives were represented by acid-activated clays and mixed oxides. The activation of clays in the catalyst by 5% sulfuric acid solutions was shown to enhance the resistance to nitrogen. The introduction of Mg, Al – mixed oxides in the catalytic system in the amount of 10 wt% increased its activity and resistance to indole. The highest resistance was observed for the systems containing magnesium‑aluminum oxides with a Me2 + to Me3 + molar ratio equal to 0.5: 1. Cobalt modification of these mixed oxides enhanced the activity and nitrogen resistance of the cracking catalysts. Use of such nitrogen-resistant catalysts will allow cracking of heavy raw materials.
The influence of the char internal structure and composition on heterogeneous conversion of naphthalene Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-26 Diego Fuentes-Cano, Francesco Parrillo, Giovanna Ruoppolo, Alberto Gómez-Barea, Umberto Arena
This work studies the heterogeneous conversion of naphthalene over different chars at 800 °C and 900 °C with gas residence times ranging from 0.05 s to 0.15 s. The aim was to analyse the role of the pore size distribution and surface composition on the catalytic activity of the char during batch experiments with a steady gas flow doped with naphthalene. The char samples were produced by steam activation using the same parent material (a pyrolysed Colombian coal). The activation aimed at generating chars with increasing porosities but similar surface composition. An ash-leached char was also prepared to investigate the role of the ash-forming elements on the char activity. The evolution of the naphthalene conversion in the gas phase and the pore size distribution of the char were measured during the tests. The initial naphthalene conversion and the char deactivation rate were seen to be strongly influenced by the concentration of alkali and alkaline earth metallic (AAEM) elements in the char. In absence of AAEM elements, the char surface was rapidly deactivated due to the depletion of surface oxo-groups produced during the char activation. The steam activation of unleached chars does not influence their inherent surface reactivity but significantly enhances the amount of surface area available for tar conversion. A linear correlation between the reaction rate coefficient and the mesopore surface area was determined for the chars with similar surface composition but different pore size distribution.
Effect of composition of coke deposited in delayed coker furnace tubes on on-line spalling Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-26 Harender Bisht, Vijai Shankar Balachandran, Mitra Patel, Girish D. Sharma, Ashwani H. Yadav, Dwaipayan D. Biswas, Sreenivas Pacharu, Sukumar Mandal, Asit K. Das
Improvement and maintenance of biochar catalytic activity for in-situ biomass tar reforming during pyrolysis and H2O/CO2 gasification Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-23 Dongdong Feng, Yu Zhang, Yijun Zhao, Shaozeng Sun, Jianmin Gao
To study the role of gasifying agents (H2O/CO2) on the improvement and maintenance of biochar catalytic activity for in situ biomass tar reforming, experiments were carried out in a two-stage fluidized-bed/fixed-bed reactor. The physicochemical properties of biochar, which are responsible for its catalytic activity during tar reforming, were analyzed by ICP–AES, SEM–EDX, BET and XPS methods. The conversion of biomass tar was investigated by GC–MS. Adding H2O or CO2 was found to improve the homogeneous and heterogeneous reforming of biomass tar, the latter of which involved first forming an intermediary coke product that was subsequently gasified by H2O/CO2. Activation of biochar by H2O/CO2 impacted the biochar surface's morphology and distribution of metal species. During tar reforming, the presence of H2O/CO2 also affected the creation and regeneration of pore structures, influencing the biochar's structure and dynamically distributing AAEM species, which ensured enough surface active sites to maintain the biochar's catalytic activity. CO2 produced more micropores in the biochar, whereas H2O favored the formation of mesopores, which are more important for tar reforming. The addition of H2O/CO2 was found to notably enhance in situ reforming of both large and small aromatic ring systems in biomass tar over biochar.
Thermo-chemical conversion for production of levulinic and formic acids from glucosamine Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-24 Mi-Ra Park, Hyo Sun Kim, Sung-Koo Kim, Gwi-Taek Jeong
Glucosamine is a monomer of chitin/chitosan, which is a renewable aquatic resource and the second most abundant biopolymer on the Earth. Moreover, methanesulfonic acid (MSA) is known as an eco-friendly green catalyst. In this study, the MSA-catalyzed conversion of glucosamine to levulinic (LA) and formic (FA) acids was optimized using the Box-Behnken statistical approach. The optimal conditions for LA yield were 50 g/L glucosamine, 0.5 M MSA, 200 °C and 30 min, which yielded 49.9% LA and 50.8% FA. The LA yield increased linearly with increasing combined severity factor (CSF) until 3.5 and then, was maintained as the CSF value was further increased. The FA yield behaved similarly to LA. Both trends fitted well to a sigmoid regression model with a high regression value. These results highlight the potential of glucosamine for biofuel and chemicals production via an MSA-catalyzed conversion system.
Effect of temperature on product performance of a high ash biomass during fast pyrolysis and its bio-oil storage evaluation Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-21 N. Gómez, S.W. Banks, D.J. Nowakowski, J.G. Rosas, J. Cara, M.E. Sánchez, A.V. Bridgwater
Bio-oil from the fast pyrolysis of agro-residues still needs to contemplate different production scenarios to look for its feasibility. For this reason, in this work the effect of a range of fast pyrolysis temperature (450, 480, 510 and 550 °C) processing rape straw biomass (with high K content) has been studied in a continuous bubbling fluidised bed reactor. It was found that the catalytic effect of the inorganic content was different at each fast pyrolysis temperature, with the lower temperatures resulting in the highest yield of bio-oil due to minor catalytic effect (up to 41.39 wt%). It was also found that at 480 °C the bio-oil presented the best combination of physico-chemical features such as non-separation phase and the lowest water content; yield (39.65 wt%) and HHV (19.23 MJ/kg), containing a high concentration of phenolic compounds. At the fast pyrolysis temperature of 510 °C and 550 °C, the conjunction effect of temperature and the catalytic effect provoked bio-oil separation into two phases and a higher gas yield than was expected. Then, the higher temperatures are not suitable for bio-oil production. Char is also an interesting co-product for all pyrolysis temperatures.
Oxy-fuel co-combustion of sewage sludge and wood pellets with flue gas recirculation in a circulating fluidized bed Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-21 Jin-Ho Sung, Seung-Ki Back, Bup-Mook Jeong, Jeong-Hun Kim, Hang Seok Choi, Ha-Na Jang, Yong-Chil Seo
Microwave torrefaction of Prosopis juliflora: Experimental and modeling study Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-21 Pradeep Natarajan, Dadi V. Suriapparao, R. Vinu
Experimental study on combustion characteristics of pulverized coal preheated in a circulating fluidized bed Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-15 Chengbo Man, Jianguo Zhu, Ziqu Ouyang, Jingzhang Liu, Qinggang Lyu
A new technique to preheat pulverized coal in a circulating fluidized bed was adopted. This technique consists of two stages: the pulverized coal is first self-preheated in a circulating fluidized bed, and then the preheated fuel gas and char particles are burned out in a down-fired combustor under air-staging conditions. Experiments were conducted with two types of coals, two air ratios in the circulating fluidized bed and different air distributions in the combustor. The preheating and combustion processes ran stably under all experimental conditions. For both types of coals, the preheating temperatures in the circulating fluidized bed could be adjusted broadly within 800–950 °C, and the ratios of primary air could be lowered to 0.15. The combustion efficiency and nitrogen conversion were remarkably influenced by the air distribution, and were controlled above 98% and below 10% respectively, although the two targets could not be simultaneously achieved.
Synthesis and characterization of Beta-FDU-12 and the hydrodesulfurization performance of FCC gasoline and diesel Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-14 Qing Wu, Yuyang Li, Zhanggui Hou, Jing Xin, Qian Meng, Longnian Han, Chengkun Xiao, Di Hu, Aijun Duan, Chunming Xu
Operation characteristics of external heat exchangers in the 600 MW supercritical CFB boiler Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-15 Runxia Cai, Man Zhang, Xin Mo, Junfu Lyu, Hairui Yang, Xiujian Lei, Wen Ling, Hu Su, Qi Zhou
Chemical-looping technologies using circulating fluidized bed systems: Status of development Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-08 Tobias Mattisson, Martin Keller, Carl Linderholm, Patrick Moldenhauer, Magnus Rydén, Henrik Leion, Anders Lyngfelt
In chemical-looping combustion (CLC), an oxygen carrier provides lattice oxygen for complete combustion of a fuel for heat and power production. The reduced metal oxide is then oxidized in a separate reactor. The combustion products CO2 and H2O are obtained in pure form, without any nitrogen in the gas. As no gas separation work is needed, this could be a breakthrough technology for carbon capture (CCS). Normally, the fuel- and air-reactor are designed utilizing inter-connected fluidized beds. The same underlying reversible redox reactions of CLC can be used for other fuel conversion technologies. These include fluidized bed processes for gas, solid and liquid fuels for heat, power, syngas or hydrogen production. Some of these concepts were suggested as far back as the 1950's, while others have just recently been proposed. This paper will provide a review of some recent developments with respect to CLC with gaseous, liquid and solid fuels, with focus on operational experience. Today, more than 35 continuous units have been used worldwide, with over 9000 h of operational time. Although most experience has been reported for methane and natural gas, significant testing has now also been performed with various solid fuels. Some recent developments include i) shift from Ni-based materials to more benign metal oxide oxygen carriers, ii) use of different types of biomass and iii) operation at semi-commercial scale. Furthermore, this paper will also provide an overview some related technologies which also utilize oxygen carriers in interconnected fluidized beds: i) Chemical-looping gasification (CLG), ii) Chemical-looping reforming (CLR) and iii) Chemical-looping tar reforming (CLTR). In these processes, a pure syngas/hydrogen can be produced effectively, which could be utilized for chemical or fuel production.
Selective removal of sodium and calcium from low-rank coal – Process integration, simulation and techno-economic evaluation Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-09 Song Zhou, Tahereh Hosseini, Xiwang Zhang, Nawshad Haque, Lian Zhang
This paper has addressed the techno-economic feasibility regarding the selective removal of sodium (Na) and calcium (Ca) from low-rank sub-bituminous coal, aiming to reduce the ash slagging and fouling propensity in the pulverized coal-fired boilers. Four novel process integrations were proposed and simulated in Aspen Plus. Both the novel counter-current three-stage water washing process and an acid-water two-stage washing process have proven to improve the ash fusion temperature satisfactorily, reducing the mass fraction of Na2O in ash from 4.32 wt% to 0.85 and 0.19 wt%, respectively. In addition, the use of acid-water washing removed 12.5% CaO and 19.5 wt% total ash. For the recycle and treatment of wastewater, the water gain is desirable for the use of an evaporator, owing to the dewatering of the initially high-moisture coal (25 wt%) in the centrifugal and the high water recovery rate from the evaporator. However, the good performance of evaporator was counteracted by the considerable capital cost caused by the huge heat transfer area requirement. Instead, the use of reverse osmosis (RO) resulted in a water loss up to 228.4 kg/t coal. Additionally, prior to the RO treatment unit, the recycle and reuse of the unsaturated water for maximum six times and four times for three-stage water washing and acid-water two-stage washing, respectively, was critical in reducing both the water and power consumption. The water consumption dropped to 38.1 kg/t coal and 48.1 kg/t coal for the three-stage water washing and acid-water two-stage washing process, respectively. Both are remarkably lower than 85.0 kg-water/t black coal. In terms of the power consumption, it decreased to ~ 9.4 kWh/t coal for the three-stage water washing process and further down to 5.8 kWh/t for the acid-water washing case, which was even slightly lower than 6.3 kWh/t for the black coal. Furthermore, the integration of acid-water washing and RO was also demonstrated to be economically viable by its high NPV, IRR and short payback period. Sensitivity analysis indicate that, the original Na content in raw coal is the most influential variable on the water and power consumption of the overall process, followed by the initial moisture content in the raw coal. For a low-rank coal containing > 2150–2520 ppm Na and/or < 19 wt% moisture, the washing process proposed would turn economically unviable compared to the existing black coal washing process. A minimum selling price of 136 RMB/t (− 32% deviation) was also necessary to keep both NPV and IRR positive as well as the payback period shorter than the project lifetime.
Hydrodeoxygenation and hydroisomerization of palmitic acid over bi-functional Co/H-ZSM-22 catalysts Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-11 Yaya Cao, Yanchun Shi, Yunfei Bi, Kejing Wu, Shaojian Hu, Yulong Wu, Shaobin Huang
Hydrodeoxygenation and hydroisomerization of palmitic acid were achieved over bi-functional Co/H-ZSM-22 catalysts (about 4 wt% Co loading), and the maximum of isoproducts reached up to 73.4% selectivity at 260 °C for 4 h in presence of 2 MPa H2. Compared to parent H-ZSM-22, the impregnation of Co species for bi-functional catalysts could catalyze completely palmitic acid conversion into 100% selectivity of alkanes in spite of low pressure (1 MPa H2). Furthermore, bi-functional Co/H-ZSM-22 catalysts tailored the deoxygenation route via hydrodeoxygenation leading to more C16 formation. With decreasing of reaction pressure, mole ratio of C16/C15 decreased during complete conversion of palmitic acid, indicating that low reaction pressure favored hydrodecarbonylation to produce more C15. Bi-functional Co/H-ZSM-22 catalysts also exhibited great stability after five runs without any deactivation.
Characterization of calcium looping sorbents with a novel twin bed reactor Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-13 Antonio Coppola, Fabrizio Scala, Piero Salatino
The experimental characterization of sorbents for Calcium Looping (Ca-L) processes is generally accomplished by thermogravimetric analysis or by using single fluidized bed bench scale reactors. These methods may present limitations, the most significant being the poor ability to reproduce the thermal history that sorbent particles experience in a real Ca-L plant. This limitation may severely affect the correct evaluation of the sorbent behavior in terms of CO2 capture capacity and attrition. In this study, a purposely developed experimental apparatus is applied for Ca-based sorbent testing under conditions that simulate a realistic thermal history of the sorbent. The apparatus consists of two identical lab-scale bubbling beds (Twin Beds - TB) operated batchwise as the calciner and the carbonator, respectively. The reactors are connected to each other via a rapid solids pneumatic transfer line, designed so as to enable rapid and selective transfer of the sorbent from one reactor to the other at the end of each calcination/carbonation stage. The two beds consist mostly of coarse-grained silica sand, acting as a thermal ballast, to which sorbent samples to be characterized are added. The TB apparatus has been used to investigate the effect of the thermal history on the performance of two limestones, in terms of CO2 capture capacity and attrition tendency, upon multiple calcination/carbonation cycles under the typical operating conditions of the Ca-L process. The results have been compared with those obtained for the same sorbents carried out in a single lab-scale fluidized bed reactor (SB) and under the same operating conditions. The comparison showed that the CO2 capture capacity in the TB system is larger than that found in SB tests for both sorbents. On the contrary, the absence of strong thermal shocks in the TB experiments leads in general to a decrease of the attrition tendency, with a reversal in terms of generated fines between calcination and carbonation stages. Indeed, the generation rate of fines measured in the TB tests during carbonation is smaller than that measured in the corresponding calcination stage, which is opposite to what was found during the tests in the SB device. These findings indicate that the sorbent thermal history plays a non-negligible role on its CO2 capture performance in Ca-L.
Aggravated fine particulate matter emissions from heating-upgraded biomass and biochar combustion: The effect of pretreatment temperature Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-11 Zhongfa Hu, Xuebin Wang, Adewale Adeosun, Renhui Ruan, Houzhang Tan
Heat pretreatment is a promising method for biomass upgrading. However, PM formation from the combustion of such pretreated biomass has not been fully evaluated. In this work, the effect of pretreatment temperature on PM emission of the upgraded biomass and biochar combustion was studied in an entrained flow reactor. The physical and chemical properties of upgraded biomass, biochar and PMs at varied pretreatment temperatures were obtained to illustrate the PM formation mechanism. Results show that pretreatment temperature significantly affects the concentration and particle size distribution of PM emissions, through changing the char yield and K/Cl contents in char. With increase in pretreatment temperature, the PM1.0 emission of upgraded biomass and biochar combustion first increases, reaches maximum at 500 °C, and then decreases. A linear relationship between the PM1.0 emission and Cl content in upgraded biomass and biochar was found. This result indicates that the combustion of upgraded biomass and biochar produced at moderate temperatures of 250–500 °C result in aggravated fouling and PM emissions.
Modelling of indirect steam gasification in circulating fluidized bed reactors Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-12 Kari Myöhänen, Juha Palonen, Timo Hyppänen
The indirect steam gasification in circulating fluidized bed reactors was studied by modelling. The object of study was a coupled 12 MWth gasifier-combustor system, which was fired by woody biomass. The heat for the steam-blown gasifier was produced in the air-blown combustor and transported by circulating solids between the interconnected reactors. The system was modelled by a semi-empirical three-dimensional model, which simulated the fluid dynamics, reactions, and heat transfer in the coupled process. The studied cases included different temperature levels, which were controlled by the amount of additional fuel feed to the combustor. The model concept can be later applied to study sorption enhanced gasification, which is a promising method for sustainable production of transport fuels to substitute fossil based fuels.
Green diesel production via continuous hydrotreatment of triglycerides over mesostructured γ-alumina supported NiMo/CoMo catalysts Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-12 Arsia Afshar Taromi, Serge Kaliaguine
Particle agglomeration during fluidized bed combustion: Mechanisms, early detection and possible countermeasures Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-13 Fabrizio Scala
Particle agglomeration in fluidized bed systems has been observed in several industrial processes. Bed particles tend to agglomerate when the cohesive force between the particles is strong enough to compare with the other acting forces (gravitational, drag). This cohesive force may arise because of different types of interactions: van der Waals, electrostatic, capillary, viscous, sintering, adhesive, chemical reaction, and so on. The most extensively reported case in the literature is concerned with the fluidized bed combustion of biomass, waste or low-rank coals, containing significant amounts of low-melting compounds (typically alkali metals) in the ash. The occurrence of bed agglomeration in such systems implies the unscheduled shut down of the reactor and costly maintenance operations. Therefore, a great deal of research has been devoted to understand and characterize agglomeration during fluidized bed combustion. This short review is focused on this specific system and tries to summarize the present status of understanding of the mechanisms leading to agglomeration, as well as the influence of the different operating variables on this phenomenon. In addition, because of their great practical importance, the possible early detection techniques and operational countermeasures are also briefly described.
Comparing the structural development of sand and rock ilmenite during long-term exposure in a biomass fired 12 MWth CFB-boiler Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-13 Angelica Corcoran, Pavleta Knutsson, Fredrik Lind, Henrik Thunman
Oxygen Carrier Aided Combustion (OCAC) is a novel combustion concept with the purpose to increase the overall efficiency in conventional circulating fluidized bed (CFB) boilers. By replacing the commonly used bed material with an oxygen carrier (OC), the conceptual idea is to utilize the fluid dynamics in a CFB and the inherent oxygen transport supported by the OC to increase the oxygen distribution within the furnace in time and space. The OCAC concept has been successfully validated and further reached long-term demonstration in full scale operation (75-MWth). This work presents a first evaluation of how ilmenite particles are affected in regard to mechanical resistance during long-term exposure to OCAC conditions in Chalmers 12-MWth CFB-boiler. A sand and a rock ilmenite are evaluated with regard to their mechanical stability. For evaluation, samples of the fresh materials and samples collected during operation in the Chalmers boiler are investigated. The study shows that the two materials differ in how the mechanical degradation occurs with exposure time. The sand ilmenite form cavities which are held together by an ash layer before they are shattered into numerous pieces, whereas the rock ilmenite develops distinct cracks that cause splitting of the particles.
Effect of water, fat, and protein in raw pork from swine carcasses on the pyrolytic gaseous and liquid product distribution Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-14 Yike Zhang, Zengyi Ma, Jianhua Yan
Pyrolysis is an effective way to dispose livestock carcasses. Pork is selected as meat from a representative carcass and the effect of its components (water, fat and protein) on the gaseous and liquid pyrolytic product distribution is investigated. Water has a significant influence on the amount of gaseous products formed, and its presence in raw pork (RP) leads to greater CO, H2, and CH4 yields through the steam gasification and steam reforming reactions. In addition, the presence of water results in higher conversion of N containing compounds into NH3, rather than HCN. Tar yields were mostly determined by the products obtained from the pyrolysis of fat, which include compounds derived from the cracking, decarboxylation, and decarbonylation of long chain fatty acids. The decomposition of protein led to the formation of small molecules like NH3, HCN, and phenols. In addition, protein and fat pyrolysis products react to form long chain amides and nitriles, increasing the tar yield. More toxic heterocyclic compounds are obtained in pyrolytic tar through the cyclisation of long chain hydrocarbons and nitriles under higher temperatures.
Techno-economic and environmental analysis of aviation biofuels Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-16 Ulf Neuling, Martin Kaltschmitt
The global awareness to reduce greenhouse gas (GHG) emissions from aviation and thereby make the overall aviation sector more environmentally friendly has increased in recent years. In this context one main driver is seen in the development of advanced biofuels for aviation, which have already been used for some regular flights by various air carrier. Within this context this paper compares four different production processes for biokerosene located in northern Germany using two different types of biomass feedstock each. These conversion processes are then assessed in terms of technical, economic and environmental criteria based on data retrieved from an extensive process simulation. Main outcome of this analysis are mass and energy balances, kerosene production costs and GHG emissions for the investigated conversion routes. The results of the investigated criteria are scattering significantly; i.e. no “silver bulled” can be seen based on these findings. Nevertheless, the significant influence of the provision of the biomass feedstock becomes obvious. Generally spoken the more environmentally sound and economic viable the feedstock provision can be realized, the more promising is the resulting biokerosene related to the economic and environmental criteria assessed here. This result is more or less independent from the respective conversion route.
VOC off-gassing from pelletized steam exploded softwood bark: Emissions at different industrial process steps Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-20 Eleonora Borén, Sylvia H. Larsson, Mikael Thyrel, Andreas Averheim, Markus Broström
Relevance of plant design on CLC process performance using a Cu-based oxygen carrier Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-20 Alberto Abad, Pilar Gayán, Francisco García-Labiano, Luis F. de Diego, Juan Adánez
Previously validated mathematical CLC models were used to simulate the process performance of CLC methane combustion using an impregnated Cu-based material and to analyse the effect of the fuel reactor design; being either a bubbling fluidized bed or a circulating fluidized bed. The CLC models considered both the fluid dynamic of the fluidized beds at the specific regime and the corresponding kinetics of oxygen carrier reduction. From the model outputs, the performance of the different systems was assessed by calculating the methane conversion in the fuel reactor. Main results highlights that the selection of a suitable particle size of the oxygen carrier and cross section area are key factors to achieve complete combustion with low solids inventory in the fuel reactor. In addition, the growing of bubbles should be limited in order to achieve high CH4 conversion with low solids inventory values, mainly in the bubbling regime with low cross section areas. Complete combustion was predicted with solids inventory in the fuel reactor of 250 kg/MWth (1 m2/MW and particle size of 0.25 mm) or 125 kg/MWth (0.2 m2/MW and a particle size of 0.15 mm) in the bubbling and turbulent regime, respectively. Considering the pressure drop related to these conditions, conclusions for the optimization design of a CLC unit using the Cu-based oxygen carrier are drawn based on the results of the modelling and simulation.
Co-production of syngas and potassium-based fertilizer by solar-driven thermochemical conversion of crop residues Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-21 F. Müller, H. Patel, D. Blumenthal, P. Poživil, P. Das, C. Wieckert, P. Maiti, S. Maiti, A. Steinfeld
Influence of the conditions for reforming HDPE pyrolysis volatiles on the catalyst deactivation by coke Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-06 Itsaso Barbarias, Maite Artetxe, Gartzen Lopez, Aitor Arregi, Javier Bilbao, Martin Olazar
Evaluation of fast pyrolysis feedstock conversion with a mixing paddle reactor Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-21 S. Zinchik, J.L. Klinger, T.L. Westover, Y. Donepudi, S. Hernandez, J.D. Naber, E. Bar-Ziv
We have developed a pyrolysis reactor based on a unique auger-paddle configuration with heat transfer material (HTM) and proved to achieve high heating rates and fast pyrolysis. We tested ten different biomass types and obtained bio-oil yields ranging from approximately 40% for thermally treated wood, to approximately 57% for crop residues (corn stover) and 67% yield for woody feedstocks (tulip poplar). These results, as well as the solid char yields, are similar to those obtained for the same feedstock using a circulating fluidized bed. Tests conducted without HTM resulted in lower bio-oil yields (ranging from 8 to 18% decrease in yield) and higher char yields with similar changes in magnitude, which is indicative of slow pyrolysis. In addition, a comprehensive study and analysis of the material residence time and mixing characteristics of the novel auger-paddle system is presented. These results demonstrate that an auger-paddle configuration is capable of achieving the high heating rates required for fast pyrolysis.
Formic acid and acetic acid production from corn cob by catalytic oxidation using O2 Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-22 Ting Lu, Yucui Hou, Weize Wu, Muge Niu, Yupeng Wang
Direct conversion of raw biomass to fine chemicals is of significant conceptual and practical interest. Up to now, the direct conversion of raw biomass to fine chemicals is still a big challenge. The oxidation of biomass to formic acid (FA) and acetic acid (AA) is a promising industrial process in the future. In this work, we reported that a binary catalyst system of Keggin-type heteropoly acid H5PV2Mo10O40 + H2SO4 was efficient to directly convert corn cob, a highly abundant renewable agricultural waste, to FA and AA using O2 as the oxidant in aqueous solutions. The effects of catalyst amount, H2SO4 concentration, reaction temperature, reaction time and initial O2 pressure on the conversions of corn cob were investigated. Under optimized reaction conditions, corn cob was transformed with a FA yield of 42.5% and an AA yield of 9.1% (based on carbon) after 30 min of reaction at 170 °C. In the oxidation, the pH of the aqueous solution plays a key role. The influences of pH on solid degradation, reaction pathway and oxidation of the components of corn cob were discussed. Hemicellulose is oxidized rapidly followed by partly oxidation of lignin, and cellulose is the most difficult converted part. Products FA and AA mainly come from polysaccharides (hemicellulose and cellulose) and pH has a major influence on cellulose. The recycling of the catalyst system is demonstrated and shows good reusability.
Micro- and mesoporous-enriched carbon materials prepared from a mixture of petroleum-derived oily sludge and biomass Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-22 Jun Wang, Chen Sun, Bing-Cheng Lin, Qun-Xing Huang, Zeng-Yi Ma, Yong Chi, Jian-Hua Yan
An innovative way of producing micro-mesoporous enriched active carbon (AC) materials from mixtures of petroleum industrial waste (oily sludge) and agricultural residue (rice husk) is presented. The quality of the products was evaluated by N2 adsorption–desorption isotherms and methylene blue (MB) adsorption tests. The asphaltene content of the oily sludge significantly affected the AC's specific surface area. The higher asphaltene content led to a higher specific surface area (2575 m2/g) than that observed for the mixture with a lower asphaltene content (1849 m2/g). Moreover, the ACs derived from mixtures of raw materials exhibited lower microporosity levels than those prepared with only oily sludge or rick husk. This may have been caused by the asphaltenes contained in oily sludge forming a carbon skeleton with the ash from the rice husk wrapped inside, generating more mesopores. The products prepared from the mixture also possessed far more oxygen-containing functional groups than AC produced from oily sludge alone. Meanwhile, the cellulose in the rice husk appeared to increase the amount of oxygen-functional groups in the AC products. The highest MB adsorption capabilities for the two AC samples were 588.24 and 757.58 mg/g for AC-S1-3 and AC-S2-3, respectively. The Langmuir model fitted the experimental data better than the Freundlich model, suggesting the process can be described as homogeneous monolayer adsorption. X-ray diffraction and X-ray photoelectron spectroscopy data revealed the amorphous nature of the carbon in the AC products. Overall, mixtures of oily sludge and rice husk offer a promising option for preparing porous AC.
Numerical simulation of catalytic upgrading of biomass pyrolysis vapours in a FCC riser Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-23 Panneerselvam Ranganathan, Sai Gu
Catalytic upgrading of biomass pyrolysis vapours is a potential method for the production of hydrocarbon fuel intermediates. This work attempts to study the catalytic upgrading of pyrolysis vapours in a pilot scale FCC riser in terms of hydrodynamics, residence time distribution (RTD) and chemical reactions by CFD simulation. NREL's Davison Circulating Riser (DCR) reactor was used for this investigation. CFD simulation was performed using 2-D Eulerian–Eulerian method which is computationally less demanding than the alternative Euler-Lagrangian method. First, the hydrodynamic model of the riser reactor was validated with the experimental results. A single study of time-averaged solid volume fraction and pressure drop data was used for the validation. The validated hydrodynamic model was extended to simulate hydrodynamic behaviours and catalyst RTD in the Davison Circulating Riser (DCR) reactor. Furthermore, the effects on catalyst RTD were investigated for optimising catalyst performance by varying gas and catalyst flow rates. Finally, the catalytic upgrading of pyrolysis vapours in the DCR riser was attempted for the first time by coupling CFD model with kinetics. A kinetic model for pyrolysis vapours upgrading using a lumping kinetic approach was implemented to quantify the yields of products. Five lumping components, including aromatic hydrocarbons, coke, non–condensable gas, aqueous fraction, and non–volatile heavy compounds (residue) were considered. It was found that the yield of lumping components obtained from the present kinetic model is very low. Thus, the further research needs to be carried out in the area of the kinetic model development to improve the yield prediction.
Xinjiang lignite ash slagging and flowability under the weak reducing environment at 1300 °C – A new method to quantify slag flow velocity and its correlation with slag properties Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-23 Xiaojiang Wu, Hengsong Ji, Baiqian Dai, Lian Zhang
In this study, a novel measurement method for the direct visualisation and quantification of lignite slag flowability has been established. The ash slagging was tested under a weak reducing environment (1% CO2 in nitrogen) at temperature range from 1000 to 1300 °C to mimic a cyclone combustion furnace for the Chinese Xinjiang lignite. Five different ash samples with a broad variation on the basicity, i.e. base/acid ratio from 1.98 to 0.27, and their blends with up to 40 wt% clay were loaded on a 25°–inclined corundum substrate and exposed to the above-mentioned reducing gases in a pre-heated horizontal furnace. The thermodynamic equilibrium software, FactSage 6.4 and typical viscosity equations were also employed to quantify the liquid fraction in each slag and its viscosity, respectively. Efforts were further made to correlate the calculated liquid fraction and viscosity of a slag and its flow velocity. As has been found, the neutral ash with the lowest ash fusion temperature is the only original ash sample that can melt and flow at 1300 °C without the use of clay additive, although its flow velocity is quite marginal. The addition of clay into basic ashes, at 8–10 wt% is able to improve the slag flow velocity by 6–7 times at 1300 °C. Both ash basicity and liquid fraction within an ash are critical in determining the slag flow velocity. However, neither has proven to be a sole and sufficient factor affecting the slag flowability. The slag viscosity is believed to be a key factor counter balancing the liquid fraction within a slag. This hypothesis was proven by the addition of 5–10 wt% MgO into a basic ash that decreased both the liquidus fraction and slag viscosity. Since the decrease on the slag viscosity (based on the calculation) was more remarkable than the liquidus fraction, the slag flow velocity was improved consequently. Apart from providing a new method to quantify slag flowability, this study also paved a direction for the future study focusing on lignite ash slag viscosity and modelling approach to correlate lignite slag properties and its flow velocity. A universal method has yet to be established for either of them.
Highly efficient extraction of phenolic compounds from oil mixtures by trimethylamine-based dicationic ionic liquids via forming deep eutectic solvents Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-23 Youan Ji, Yucui Hou, Shuhang Ren, Congfei Yao, Weize Wu
Calcium sulfation characteristics at high oxygen concentration in a 1MWth pilot scale oxy-fuel circulating fluidized bed Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-24 Wei Li, Mingxin Xu, Shiyuan Li
In the present study, tests were conducted to investigate the behaviour of sulfur capture by calcium based sorbents during oxy-fuel circulating fluidized bed combustion at high oxygen concentrations via a 1MWth pilot-scale oxy-fuel circulating fluidized bed facility. The effects of operating temperature, overall oxygen concentration, and Ca:S molar ratio were taken into consideration. It was determined that the efficiency of sulfur capture during oxy-fuel combustion was higher than that during air combustion. Meanwhile, with the increase of oxygen concentration, the efficiency of sulfur capture increased. Comparing with the optimum temperature for sulfur capture during air combustion, the optimum temperature during oxy-fuel circulating fluidized bed combustion was about 930 °C when the overall oxygen concentration was 50%. In addition, the optimal Ca:S molar ratio was ~ 3.0 during oxy-fuel combustion when various factors were all taken into consideration.
Pressurised chemical-looping combustion of an iron-based oxygen carrier: Reduction kinetic measurements and modelling Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-27 Z. Zhang, J.G. Yao, M.E. Boot-Handford, P.S. Fennell
Chemical-looping combustion (CLC) is a novel combustion techology offering the potential to provide uninterrupted and reliable heat and power production from fossil or bio-derived fuels with integrated, intrinsic CO2 capture and minimal energy penalty. Operation of CLC at elevated pressures provides the potential for integration with a combined cycle, which makes the use of solid fuels significantly more feasible. To date, only a few experimental studies investigating CLC processes and oxygen carrier performance under pressurised conditions have been reported in the open literature. This article reports findings from investigations into the effect of pressure, temperature and CO concentration on the intrinsic reaction kinetics of an Al2O3-supported Fe-based oxygen carrier. Our study employed an innovative pressurised fluidised-bed reactor, designed for operation at temperatures up to 1273 K and pressures up to 20 bara, to simulate ex-situ gasification of solid fuels at elevated pressures. An intrinsic reaction model was developed and pseudo-intrinsic rate constants were derived. Differences in the activation energies and pre-exponential factors of the Al2O3-supported Fe2O3 and a pure Fe2O3 oxygen carriers were observed, indicating a change in reaction mechanism when Al2O3 was present. Subsequently, an adapted random pore model was developed to describe the variation of reaction rate with solid conversion. The good agreement between the adapted random pore model and empirical measurements indicated that the change in mechanism was due to a significantly higher product layer diffusivity for the Al2O3-supported Fe2O3 oxygen carrier compared with the pure Fe2O3 material. When pressurised, the observed reaction order with respect to CO was slightly lower than 1. The model developed using atmospheric pressure measurements was successfully applied to predict reaction kinetics at elevated pressures up to 5 bara providing further validation of the model.
The extent of sorbent attrition and degradation of ethanol-treated CaO sorbents for CO2 capture within a fluidised bed reactor Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-01 Peter T. Clough, Gianluca Greco, Maria Erans, Antonio Coppola, Fabio Montagnaro, Edward J. Anthony
The application of an ethanol pre-treatment step on biomass-templated calcium looping sorbents resulting in an improved pore structure for cyclic CO2 capture was investigated. Three ethanol solutions of varying concentrations were used with an improved pore and particle structure, and thermogravimetric analyser CO2 carrying capacity arising with the 70 vol% ethanol solution. The extent of attrition of these sorbents was tested within a fluidised bed reactor and compared against an untreated sorbent and a limestone base case. It found that despite the ethanol-treated sorbents displaying an admirable CO2 carrying capacity within the thermogravimetric analyser even under realistic post-combustion conditions, this was not translated equivalently in the fluidised bed. Attrition and elutriation of the biomass-templated sorbents was a significant issue and the ethanol pre-treatment step appeared to worsen the situation due to the roughened surface and mechanically weaker structure.
Destruction of tar during volatile-char interactions at low temperature Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-27 Yao Song, Yijun Zhao, Xun Hu, Lei Zhang, Shaozeng Sun, Chun-Zhu Li
This study aims to investigate the mechanisms of tar destruction during volatile-char interactions at low temperature (400–700 °C). A bio-char was subjected to interactions with biomass volatiles at different temperatures (400–700 °C). The results indicate that tar is converted into gaseous and solid products (coke) during volatile-char interactions and the proportion of coke formed on the bio-char from the total converted tar steadily increases with increasing temperature. The non-aromatic structures (e.g. aliphatic and/or O-containing structures) in tar are mainly converted into gases by catalytic cracking and/or reforming reactions on char, while the aromatic structures in tar primarily go through condensation/polymerisation reactions to form coke on char surface. The UV-fluorescence spectroscopic results imply that the non-aromatic structures in tar are easier converted on char than aromatic structures at low temperature (e.g. 400–500 °C) and the conversion of aromatic structures through coke formation on char will be enhanced at higher temperature (e.g. 600–700 °C). The Raman spectroscopic results show that some O-containing species in tar molecules are transferred to the char and form additional O-containing structures into the entire char matrix during the volatile-char interactions.
Deposition of fine particles of gas oil on hydrotreating catalyst: Impact of process parameters and filtration trends Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-27 Rachita Rana, Ajay K. Dalai, Yongfeng Hu, John Adjaye
Combustion measurements of type-1 pulverized coal flames operating under oxy-fired conditions Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-27 Rodrigo Corrêa da Silva, Hans Joachim Krautz
The present study addresses the impact of oxy-fired conditions on type-1 flames generated by an oxidant-staged burner operating with pre-dried lignite and applying wet flue-gas recirculation. Investigations were carried out in a laboratory facility where the combustion takes place in a furnace with a rated capacity of 0.40 MWth. In-flame measurements were performed for oxy-fired conditions operating at three levels of secondary swirl number (1.15, 1.65, and 2.05), while overall O2 fraction upstream of the burner in oxy-firing was kept at 31 vol%. One air-fired condition at 1.65 secondary swirl number was also investigated. Measurements of local gas temperature and gas species concentrations were performed using standard water-cooled probes with focus on the near burner region. Results showed evidence of radial flame stratification consistent with gradual O2 admixing to the central fuel jet. Lower temperatures on the flame axis were obtained under oxy-fired condition. In the same region, as a result of CO2 dissociation and/or gasification reactions by water vapor and CO2, higher CO concentrations were also monitored, which contributed to lower temperatures. Experimental data also suggested great potential for NO abatement through flame stratification due to type-1 flame pattern.
An efficient coal pyrolysis model for detailed tar species vaporization Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-28 Jianqing Li, Simcha L. Singer
An accurate and computationally efficient model for the vaporization of many tar species during coal particle pyrolysis has been developed. Like previous models, the molecular fragments generated by thermal decomposition are partitioned into liquid metaplast, which remains in the particle, and vapor, which escapes as tar, using a vapor-liquid equilibrium (VLE) sub-model. Multicomponent VLE is formulated as a rate-based process, which results in an ordinary differential equation (ODE) for every species. To reduce the computational expense of solving many ODEs, the model treats tar and metaplast species as a continuous distribution of molecular weight. To improve upon the accuracy of previous continuous thermodynamic approaches for pyrolysis, the direct quadrature method of moments (DQMoM) is proposed to solve for the evolving distributions without assuming any functional form. An inexpensive delumping procedure is also utilized to recover the time-dependent mole fractions and fluxes for every discrete species. The model is well-suited for coal-to-chemicals processes, and any application which requires information on a range of tar species. Using a modified CPD model as the basis for implementation of the VLE submodel, agreement between the full discrete model and DQMoM with delumping is excellent, with substantial computational savings.
Density functional study of hydrogen sulfide adsorption mechanism on activated carbon Fuel Process. Technol. (IF 3.752) Pub Date : 2017-11-28 Fenghua Shen, Jing Liu, Zhen Zhang, Yuchen Dong, Chenkai Gu
A systematic theoretical study using the density functional theory was performed to provide molecular-level understanding on the adsorption of hydrogen sulfide (H2S) on activated carbon. Both zigzag and armchair edge sites of benzene ring models were considered as the possible active sites. The results indicate that the adsorption of H2S molecule on activated carbon is highly thermally favorable. The adsorption energies of H2S on zigzag and armchair edges are − 664.9 and − 349.6 kJ/mol, respectively. Activated carbon plays double role, not only facilitates the dissociation of H2S molecule but also offers active sites for H2S adsorption. The dissociative adsorption and evolution of H2S lead to the formations of C S, C S C and C SH, which is in agreement with experimental data. The shape of the local active site has a strong effect on H2S adsorption. The atomic charge of zigzag edge sites is more negative than that of armchair edge sites. Thus, the zigzag edge sites provide stronger force to attract H2S than the armchair edge sites. Direct adsorption of H2S leads to the formations of C S or C SH on activated carbon surface, followed by their evolution into C S C. These sulfur species including C S, C S C and C SH are stable on activated carbon.
Integrated thermo-catalytic reforming of residual sugarcane bagasse in a laboratory scale reactor Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-01 Ejaz Ahmad, Nils Jäger, Andreas Apfelbacher, Robert Daschner, Andreas Hornung, K.K. Pant
Mid- infrared uncooled sensor for the identification of pure fuel, additives and adulterants in gasoline Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-06 María Maldonado, Pilar Barreiro, Raul Gutiérrez, Germán Vergara
The aim of the present study is to test the ability of a low-cost and portable middle infrared spectrometer based on a linear array of 1 × 128 of PbSe, coupled with a linear variable optical filter in the wavelength range of 3–4.5 μm, for the differentiation of pure chemical substances and quality control of fuels. Potential additives and adulterants for gasoline were tested, considering the alcohols ethanol, n-butanol, n-propanol and n-hexanol as potential additives and methanol and diesel oils as adulterants. Multivariate analysis of variance (MANOVA) applied to the scores obtained in the Principal Component Analysis (PCA) was conducted to analyze the spectral data and distinguish between the individual components. For the purposes of classifying anonymous samples, the centroid of each pure substance in the canonical variables was calculated, followed by the distance calculated between new samples to such centroids, assigning the individual to the most proximate category. The results demonstrated that the technique was able to discriminate between gasoline, diesel oils and the alcohols methanol, ethanol, n-propanol, n-butanol and n-hexanol and that it had the potential to be applied in the fuel industry.
High-strength charcoal briquette preparation from hydrothermal pretreated biomass wastes Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-07 Shunyan Wu, Shouyu Zhang, Caiwei Wang, Chen Mu, Xiaohe Huang
The waste cotton stalk (CS) and wood sawdust (WS) biomass samples pretreated by two different thermal methods (dry torrefaction (DT) and hydrothermal treatment (HT) at 200, 230, 260 °C, respectively) were densified to prepare biomass briquette and then carbonized at 400 °C to prepare charcoal briquette without any binders. The physical properties and combustion characteristics of the derived charcoal briquettes were investigated to assess the feasibility of its application as barbecue charcoal. The results indicate that the physical properties including the mass densities and compressive strengths of HT charcoal briquettes are better than those of DT and unpretreated charcoal briquettes, even those of the commercial barbecue charcoal with binder addition. Moreover, the fixed carbon and ash yields of the resulted HT charcoal briquettes meet the European Standard on commercial barbecue charcoal. Especially HT charcoal briquettes has far lower ash yield than the commercial barbecue charcoal. HT charcoal briquettes have similar combustion character index (S) with the commercial barbecue charcoal. In the research, CS and WS hydrothermal pretreated at 230 °C are the best materials for the charcoal briquette preparation process.
Reductive carbonylation of methanol for ethanol production in Rh-Ru-dppp-methyl iodide catalytic system under mild conditions – The effect of lithium salts and catalyst composition Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-07 Yingzan Chen, Dianhua Liu
Bio-oil production from fast pyrolysis of rice husk in a commercial-scale plant with a downdraft circulating fluidized bed reactor Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-08 Wenfei Cai, Ronghou Liu, Yifeng He, Meiyun Chai, Junmeng Cai
Bio-oil, a promising candidate to replace fossil fuels, has received considerable attention for its sustainability, resource diversity and environmental benefits. Industrial production of bio-oil is urgently needed. In this study, a downdraft circulating fluidized bed reactor commercial-scale fast pyrolysis plant with biomass throughput of 1–3 t h− 1 is studied. Rice husk was processed at a fast pyrolysis temperature of 550 °C to evaluate the plant operation status. The system was continuously operated for 80.42 h. The thermal properties of the feedstock (rice husk), dust (separated from feedstock), char and heat carrier were analyzed and the bio-oil properties such as water content, pyrolytic water content, viscosity, density, pH, heating value, solid content and ash content were analyzed and presented. All the tested properties of the bio-oil meets the pyrolysis liquid biofuels standards in ASTM D7544-12 for Grade G biofuels, except for the water content of the bio-oil, which is slightly higher than that of Grade G biofuels. In energy balance analysis, the potential recovered energy of the three main products was 8.0 ± 1.1, 2.1 ± 0.1 and 5.3 ± 0.7 MJ kg− 1 for bio-oil, char and non-condensable gas, respectively, which shows that the largest portion of the energy in biomass was recovered in the bio-oil.
Efficient diagnosis of grate-fired biomass boilers by a simplified CFD-based approach Fuel Process. Technol. (IF 3.752) Pub Date : 2017-12-11 Adeline Rezeau, Luis I. Díez, Javier Royo, Maryori Díaz-Ramírez
This paper describes the development and validation of a numerical tool able to simulate biomass combustion in grate-fired systems and support operation and design improvements of these devices. The modeling method is conceived as a compromise between the demand of computing time and the degree of detail in the simulation. As such, it integrates both the bed zone and the freeboard zone on a same 3D grid and assumes the bed as a porous medium, where heterogeneous reactions are simulated by a modified laminar rate model. Liquid water, dry biomass and char are introduced as site species that react on the porous medium surfaces to produce and/or consume gas species (O2, CO, CO2, H2, H2O, light hydrocarbons and condensable gases). To validate the numerical tool, predictions have been compared to experimental data gathered in a 250 kWth combustion test facility operated with a high quality woody pellet. Once validated, the tool has been applied to characterize the flow patterns as well as the temperature and the main gaseous emissions profiles within the combustion chamber. According to the analysis of the simulation results, significant improvements have been identified concerning not only operation but also design issues.
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