Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling ...Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST tokamak.Pellet ablation and deposition profiles were evaluated for various pellet injection locations,with the aim at optimizing the pellet injection to obtain a deep fueling depth.In this study,we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and sizes.The ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles:0°,45°,and 60°.The pellet injection on the high field side(HFS)can achieve a more ideal deposition depth than on the low field side(LFS).Among these angles,horizontal injection on the middle plane is relatively better on either the HFS or the LFS.When the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS,it can achieve a similar deposition depth to the one of its corresponding side.When the pre-cooling effect is taken into account,the deposition depth is predicted to increase only slightly when the pellet is launched from the HFS.The findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.展开更多
Plastic waste is an underutilized resource that has the potential to be transformed into value-added materials.However,its chemical diversity leads to cost-intensive sorting techniques,limiting recycling and upcycling...Plastic waste is an underutilized resource that has the potential to be transformed into value-added materials.However,its chemical diversity leads to cost-intensive sorting techniques,limiting recycling and upcycling opportunities.Herein,we report an open-loop recycling method to produce graded feedstock from mixed polyolefins waste,which makes up 60%of total plastic waste.The method uses heat flow scanning to quantify the composition of plastic waste and resolves its compatibility through controlled dissolution.The resulting feedstock is then used to synthesize blended pellets,porous sorbents,and superhydrophobic coatings via thermally induced phase separation and spin-casting.The hybrid approach broadens the opportunities for reusing plastic waste,which is a step towards creating a more circular economy and better waste management practices.展开更多
A novel method of pellet calcification roasting-H_(2)SO_(4) leaching was proposed to efficiently separate and extract vanadium(V)from vanadium-titanium(V-Ti)magnetite concentrates.The leaching rate of V is as high as ...A novel method of pellet calcification roasting-H_(2)SO_(4) leaching was proposed to efficiently separate and extract vanadium(V)from vanadium-titanium(V-Ti)magnetite concentrates.The leaching rate of V is as high as 88.98%,while the leaching rate of impurity iron is only 1.79%.Moreover,the leached pellets can be used as raw materials for blast furnace ironmaking after secondary roasting.X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive X-ray spectrometry(SEMEDS)analyses showed that V^(3+)was oxidized to V^(5+)after roasting at 1200℃,and V^(5+)was then leached by H_(2)SO_(4).X-ray diffraction(XRD)analyses and single factor experiment revealed a minimal amount of dissolved Fe_(2)O_(3) during H_(2)SO_(4) leaching.Therefore,a high separation degree of V and iron(Fe)from V-Ti magnetite concentrate was achieved through H_(2)SO_(4) leaching.Compared with the traditional roastingleaching process,this process can achieve a high selectivity of V and Fe,and has excellent prospects for industrial production.展开更多
In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydra...In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical kinetics.The estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.展开更多
Air pollution is a major health problem in developing countries and has adverse effects on human health and the environment. Non-thermal plasma is an effective air pollution treatment technology. In this research, the...Air pollution is a major health problem in developing countries and has adverse effects on human health and the environment. Non-thermal plasma is an effective air pollution treatment technology. In this research, the performance of a dielectric barrier discharge(DBD) plasma reactor packed with glass and ceramic pellets was evaluated in the removal of SO_2 as a major air pollutant from air in ambient temperature. The response surface methodology was used to evaluate the effect of three key parameters(concentration of gas, gas flow rate, and voltage) as well as their simultaneous effects and interactions on the SO2 removal process. Reduced cubic models were derived to predict the SO_2 removal efficiency(RE) and energy yield(EY). Analysis of variance results showed that the packed-bed reactors(PBRs) studied were more energy efficient and had a high SO2 RE which was at least four times more than that of the non-packed reactor. Moreover, the results showed that the performance of ceramic pellets was better than that of glass pellets in PBRs. This may be due to the porous surface of ceramic pellets which allows the formation of microdischarges in the fine cavities of a porous surface when placed in a plasma discharge zone. The maximum SO_2 RE and EY were obtained at 94% and 0.81 g kWh^(-1),respectively under the optimal conditions of a concentration of gas of 750 ppm, a gas flow rate of 2lmin^(-1), and a voltage of 18 kV, which were achieved by the DBD plasma packed with ceramic pellets. Finally, the results of the model's predictions and the experiments showed good agreement.展开更多
A new pellet injection system was installed on the EAST tokamak and preliminary experiments were performed during the 2012 run campaign. Typical phenomena associated with deuterium pellet injection into a plasma disch...A new pellet injection system was installed on the EAST tokamak and preliminary experiments were performed during the 2012 run campaign. Typical phenomena associated with deuterium pellet injection into a plasma discharge have been observed including sudden increases of the electron density and Hα/Da emission intensity as well as a significant decrease in plasma electron temperature. Profiles have been studied in order to understand the influence of pellet fuelling on EAST discharges. Even though the injector was specifically designed for plasma fu- elling, ELM triggering using the pellet injection has also been tested. In order to find appropriate parameters for triggering ELMs in H-mode plasmas, scanning of the pellet injection speed was employed for pellets injected from both the high field side and low field side of the plasma column. It has been observed that low-speed pellets injected into H-mode plasma from the low-field side could trigger an ELM followed by a number of smaller induced ELMs at about 300 Hz.展开更多
Nutrient composition of the manure of four pill millipedes （Arthrosphaera dalyi, ,4. davisoni, ,4. fumosa and,4, magna） inhabiting in semi-evergreen forests and plantations of the Western Ghats of Southwest India wa...Nutrient composition of the manure of four pill millipedes （Arthrosphaera dalyi, ,4. davisoni, ,4. fumosa and,4, magna） inhabiting in semi-evergreen forests and plantations of the Western Ghats of Southwest India was evaluated. The quantity and quality of fecal pellets differed between millipedes and their habitats （forest and plantation）. Organic carbon content in manure was lower in plantations than in forests, while nitrogen content was elevated in plantations. The carbon to nitrogen （C/N） ratio of manure was lower in plantations compared to forests. The phosphorus content in manure was elevated in plantations in all except for A. dalyi. Calcium content of manure was increased in plantations than in forests. The contents of magnesium, potassium and phenolics in manure showed varied results. The mass of fecal pellets was correlated only with volume in forests （r=0.882; p 〈0.01） and pH in plantations （r=0.616; p 〈0.05）, while the volume of fecal pellets was correlated with nitrogen content in forests （r=0.751; p 〈0.01） and cal- cium in plantations （=0.619; p 〈0.05）. The conductivity was positively correlated with phosphorus and potassium, while magnesium was negatively correlated in forests as well as plantations. Potassium and magnesium were negatively correlated in forests （r=0.920; p〈0.001） and plantations （t=0.692; p 〈0.05）. Overall, the physicochemical characteristics and nutrient composition of fecal pelets differed between millipedes as well as habitats. The low carbon to nitrogen ratio and the increased nitrogen, phosphorus and calcium content in the manure of millipedes inhabiting in plantations indicates possibilities for successfully employing them for in situ composting of forest or plantation residues.展开更多
Background： Replacement of fossil fuel based energy with biochar-based bioenergy production can help reduce greenhouse gas emissions while mitigating the adverse impacts of climate change and global warming. However,...Background： Replacement of fossil fuel based energy with biochar-based bioenergy production can help reduce greenhouse gas emissions while mitigating the adverse impacts of climate change and global warming. However, the production of biochar-based bioenergy depends on a sustainable supply of biomass. Although, Northwestern Ontario has a rich and sustainable supply of woody biomass, a comprehensive life cycle cost and economic assessment of biochar-based bioenergy production technology has not been done so far in the region. Methods： In this paper, we conducted a thorough life cycle cost assessment （LCCA） of biochar-based bioenergy production and its land application under four different scenarios： 1） biochar production with low feedstock availability; 2） biochar production with high feedstock availability; 3） biochar production with low feedstock availability and its land application; and 4） biochar production with high feedstock availability and its land applicationusing SimaPro, EIOLCA software and spreadsheet modeling. Based on the LCCA results, we further conducted an economic assessment for the break-even and viability of this technology over the project period. Results： It was found that the economic viability of biochar-based bioenergy production system within the life cycle analysis system boundary based on study assumptions is directly dependent on costs of pyrolysis, feedstock processing （drying, grinding and pelletization） and collection on site and the value of total carbon offset provided by the system. Sensitivity analysis of transportation distance and different values of C offset showed that the system is profitable in case of high biomass availability within 200 km and when the cost of carbon sequestration exceeds CAD S60 per tonne of equivalent carbon （CO2e）. Conclusions： Biochar-based bioenergy system is economically viable when life cycle costs and environmental assumptions are accounted for. This study provides a medium scale slow-pyrolysis plant scenario and we recommend similar experiments with large-scale plants in order to implement the technology at industrial scale.展开更多
Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for L...Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for Li, Be, and B impurity pellets in reactor-relevant plasma has been derived. Results show compatibilities of lithium pellet injection used in α-particle diagnostics are positive in comparison with other solid impurity pellets (e.g. Be, B and C). Using the 2-D Kuteev lentil model, including kinetic effects, we find that currently existing pellet injection techniques will not meet core-fueling requirements for ITER-FEAT. A pressure as high as 254 MPa must be applied to a pellet accelerator with a 200 cm-long single-stage pneumatic gun, in order to accelerate a pellet with a radius rpo = 0.5 cm to a velocity of vpo, 24 × 105 cm/s penetrating 100 cm into the ITER plasma core. Comparisons of pellet velocity- and radius-dependent penetration depth between the Neutral Gas Shielding and the Kuteev's models are made. However, we find that the isotopic effects can lead to a 33% lower pellet speed for solid DT, compared to an identical H2 pellet penetrating the same length in ITER-FEAT plasma, and our calculations show that HFS injection will much improve core fueling efficiency.展开更多
In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane（OCM）over titanite pervoskite is developed.The method is based on a computational fluid dynamics（CFD）code whic...In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane（OCM）over titanite pervoskite is developed.The method is based on a computational fluid dynamics（CFD）code which known as Fluent may be adopted to model the reactions that take place inside the porous catalyst pellet.The steady state single pellet model is coupled with a kinetic model and the intra-pellet concentration profiles of species are provided.Subsequent to achieving this goal,a nonlinear reaction network consisting of nine catalytic reactions and one gas phase reaction as an external program is successfully implemented to CFD-code as a reaction term in solving the equations.This study is based on the experimental design which is conducted in a differential reactor with a Sn/BaTiO3 catalyst（7-8 mesh） at atmospheric pressure,GHSV of 12000 h-1,ratio of methane to oxygen of 2,and three different temperatures of 1023,1048 and 1073 K.The modeling results such as selectivity and conversion at the pellet exit are in good agreement with the experimental data.Therefore,it is suggested that to achieve high yield in OCM process the modeling of the single pellet should be considered as the heart of catalytic fixed bed reactor.展开更多
The deposition profile of the impurity pellet is measured by a two-dimensional fast- framing vacuum ultraviolet （VUV） camera system in the large helical device （LHD）. The fast framing camera selectively measures t...The deposition profile of the impurity pellet is measured by a two-dimensional fast- framing vacuum ultraviolet （VUV） camera system in the large helical device （LHD）. The fast framing camera selectively measures the emission from the hydrogen-like ions of carbon （C VI） with a frame rate of several kHz. From the emission profile of the hydrogen-like carbon ions, which are in the process of ionization, the initial deposition profile of the carbon is estimated using a simple one-dimensional transport model.展开更多
The diffusion and reaction phenomenon in a Fe-based catalyst pellet for Fischer-Tropsch synthesis was studied. It was considered that the pores of catalyst pellets were full of liquid wax under Fischer-Tropsch synthes...The diffusion and reaction phenomenon in a Fe-based catalyst pellet for Fischer-Tropsch synthesis was studied. It was considered that the pores of catalyst pellets were full of liquid wax under Fischer-Tropsch synthesis conditions. The re- actants diffused from the bulk gas phase to the external surface of the pellet, and then the reactants diffused through the wax inside the pellet and reacted on the internal surface formed along the pore passages of the pellet. On the basis of reaction kinetics and double a-ASF product distribution model, a diffusion and reaction model of catalyst pellet was established. The effects of diffusion and reaction interaction in a catalyst pellet, the bulk temperature, the reaction pressure and the pellet size on the reactivity were further investigated. The relationship between the internal diffusion effectiveness factor of spherical catalyst pellet and the Thiele modulus were also discussed. The bulk temperature and pellet size have significant effects on the reactivity, while the pressure shows only a slight influence on the reactivity. The internal diffusion effectiveness factor decreases with an increasing Thiele modulus.展开更多
A measuring system for high-speed hydrogen ice pellet was introduced in this paper and the photographing of flying pellet taken therein. With the system, a pellet (minimum size of φ 0.3 mm) velocity (ranging from 50 ...A measuring system for high-speed hydrogen ice pellet was introduced in this paper and the photographing of flying pellet taken therein. With the system, a pellet (minimum size of φ 0.3 mm) velocity (ranging from 50 m/s to 2500 m/s) can be measured in the HL-1M tokamak fueling experiments. By analyzing photographs and the conditions of frozen pellets (including gas supply, gas replenishment, temperature controlling etc), the pellet-freezing technology is summarized in the paper.展开更多
To understand the effect of injected deuterium(D)pellets on background plasma,the ablation of D pellets and the transport of D species in both atomic and ionic states in the EAST device are simulated using a modified ...To understand the effect of injected deuterium(D)pellets on background plasma,the ablation of D pellets and the transport of D species in both atomic and ionic states in the EAST device are simulated using a modified dynamic neutral gas shield model combined with the edge plasma code SOLPS-ITER.The simulation results show that there is a phenomenon of obvious atomic deposition in the scrape-off layer(SOL)after pellet injection,which depends strongly on the injection velocity.With increasing injection velocity,the atomic density in the SOL decreases evidently and the deposition time is relatively shortened.Possible effects for triggering of edge localized modes(ELMs)by D and Li pellets are also discussed.With the same pellet size and injection velocity,the maximum perturbation pressure caused by D pellets is obviously higher.It is found that the resulting maximum perturbed pressure is remarkably enhanced when the injection velocity is reduced from 300 m/s to 100 m/s for a pellet with a cross section of 1.6 mm,which indicates that the injection velocity is important for ELM pacing.This work can provide reasonable guidance for choosing pellet parameters for fueling and ELM triggering.展开更多
Pellet injection is an attractive technology for core-fueling and magnetohydrodynamic study in magnetic-conflnement fusion devices like tokamaks and stellarators.It can inject solid hydrogen/deuterium pellets into the...Pellet injection is an attractive technology for core-fueling and magnetohydrodynamic study in magnetic-conflnement fusion devices like tokamaks and stellarators.It can inject solid hydrogen/deuterium pellets into the plasma with deeper density deposition compared with other fueling methods,such as gas pufflng.A three-barrel H_(2)pellet injection system was installed on the J-TEXT tokamak and experiments were carried out.The pellets are formed in three barrels cooled by a cryocooler and compressor system at around 9 K,and are 0.8 mm/1 mm diameter and 0.8 mm length.The pellet is launched by helium propellant gas and injected from the lowfleld side of the plasma.The normal range of pellet speed is 210–310 m s^(-1)for different propellant gas pressures.Due to the three-barrel structure,the number of injected pellets can be adjusted between one and three.Pellets can be launched sequentially with arbitrary time intervals,which enables flexible applications.The results of the experiments show that pellet fueling efflciency can reach 50%.The energy conflnement time increased by about 7.5–10 ms after pellet injection.展开更多
An Ha emission measurement array with 25 detection channels has been built on HL-1M tokamak. Reconstruction maps of Ha emission distribution in plasma cross-section have been obtained by using tomography, with a hydro...An Ha emission measurement array with 25 detection channels has been built on HL-1M tokamak. Reconstruction maps of Ha emission distribution in plasma cross-section have been obtained by using tomography, with a hydrogen pellet injected into the plasma. The dimension, the shape and the rotation characteristic of the cross-section of the pellet ablation material flow tube have been observed. These results have been analysed and explained tentatively by using the ‘tail＇ model and the linear expansion model.展开更多
Scalings of the density peak and pellet penetration length in ITER are developed based on simulations using 1.5D BALDUR integrated predictive modeling code. In these simulations, the pellet ablation is described by th...Scalings of the density peak and pellet penetration length in ITER are developed based on simulations using 1.5D BALDUR integrated predictive modeling code. In these simulations, the pellet ablation is described by the Neutral Gas Shielding （NGS） model with grad-B drift effect taken into account. The NGS pellet model is coupled with a plasma core transport model, which is a combination of an MMM95 anomalous transport model and an NCLASS neoclassical transport model. The BALDUR code with a combination of MMM95 and NCLASS models, together with the NGS model, is used to simulate the time evolution of plasma current, ion and electron temperatures, and density profiles for ITER standard type I ELMy H-mode discharges during the pellet injection. As a result, the scaling of the density peak and pellet penetration length at peak density can be established using this set of predictive simulations that covers a wide range of ITER plasma conditions and pellet parameters. The multiple regression technique is utilized in the development of the scalings. It is found that the scaling for density at center is sensitive to both the plasma and pellet parameters; whereas the scalings for density and location of the additional peak are sensitive to the pellet parameters only.展开更多
The preliminary design of a multi-barrels pellet injector with cycle refrigerator as an advanced plasma-fuelling tool for HL-2A tokamak has been proposed. The design aims at precise temperature control, easy operation...The preliminary design of a multi-barrels pellet injector with cycle refrigerator as an advanced plasma-fuelling tool for HL-2A tokamak has been proposed. The design aims at precise temperature control, easy operation with high reliability and high flexibility. GM-cycle refrigerator and pipe-gun structure have been employed to produce 25 pellets in 25 gun barrels simultaneously and the design aims. have been accomplished. Prime design principle, engineering parameters, structure and layout of the cryostat components as well as calculation of heat load for the cryostat are presented.展开更多
Pneumatic and centrifugal injectors for steady-state plasma refuelling bysolid hydrogen, deuterium and tritium pellets have been designed at the PELIN Laboratory to meetrequirements of LHD, TORE SUPRA, and ITER. Prese...Pneumatic and centrifugal injectors for steady-state plasma refuelling bysolid hydrogen, deuterium and tritium pellets have been designed at the PELIN Laboratory to meetrequirements of LHD, TORE SUPRA, and ITER. Presented here is a review of these injectors' designsand results.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12205196 and 12275040)the National Key Research and Development Program of China (Grant No.2022YFE03090003)。
文摘Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST tokamak.Pellet ablation and deposition profiles were evaluated for various pellet injection locations,with the aim at optimizing the pellet injection to obtain a deep fueling depth.In this study,we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and sizes.The ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles:0°,45°,and 60°.The pellet injection on the high field side(HFS)can achieve a more ideal deposition depth than on the low field side(LFS).Among these angles,horizontal injection on the middle plane is relatively better on either the HFS or the LFS.When the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS,it can achieve a similar deposition depth to the one of its corresponding side.When the pre-cooling effect is taken into account,the deposition depth is predicted to increase only slightly when the pellet is launched from the HFS.The findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.
基金NPRP grant number NPRP12S-0325-190443 from the Qatar National Research Fund (a member of the Qatar Foundation)
文摘Plastic waste is an underutilized resource that has the potential to be transformed into value-added materials.However,its chemical diversity leads to cost-intensive sorting techniques,limiting recycling and upcycling opportunities.Herein,we report an open-loop recycling method to produce graded feedstock from mixed polyolefins waste,which makes up 60%of total plastic waste.The method uses heat flow scanning to quantify the composition of plastic waste and resolves its compatibility through controlled dissolution.The resulting feedstock is then used to synthesize blended pellets,porous sorbents,and superhydrophobic coatings via thermally induced phase separation and spin-casting.The hybrid approach broadens the opportunities for reusing plastic waste,which is a step towards creating a more circular economy and better waste management practices.
基金funded by the National Science Foundation of China(No.51704028)the Key R&D Program of Yunnan Province(No.2018IB027)。
文摘A novel method of pellet calcification roasting-H_(2)SO_(4) leaching was proposed to efficiently separate and extract vanadium(V)from vanadium-titanium(V-Ti)magnetite concentrates.The leaching rate of V is as high as 88.98%,while the leaching rate of impurity iron is only 1.79%.Moreover,the leached pellets can be used as raw materials for blast furnace ironmaking after secondary roasting.X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive X-ray spectrometry(SEMEDS)analyses showed that V^(3+)was oxidized to V^(5+)after roasting at 1200℃,and V^(5+)was then leached by H_(2)SO_(4).X-ray diffraction(XRD)analyses and single factor experiment revealed a minimal amount of dissolved Fe_(2)O_(3) during H_(2)SO_(4) leaching.Therefore,a high separation degree of V and iron(Fe)from V-Ti magnetite concentrate was achieved through H_(2)SO_(4) leaching.Compared with the traditional roastingleaching process,this process can achieve a high selectivity of V and Fe,and has excellent prospects for industrial production.
基金Ministry of Steel-India,New Delhi for sponsoring the program to carry out the research work
文摘In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical kinetics.The estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.
基金financially supported by the Tarbiat Modares University of Tehran。
文摘Air pollution is a major health problem in developing countries and has adverse effects on human health and the environment. Non-thermal plasma is an effective air pollution treatment technology. In this research, the performance of a dielectric barrier discharge(DBD) plasma reactor packed with glass and ceramic pellets was evaluated in the removal of SO_2 as a major air pollutant from air in ambient temperature. The response surface methodology was used to evaluate the effect of three key parameters(concentration of gas, gas flow rate, and voltage) as well as their simultaneous effects and interactions on the SO2 removal process. Reduced cubic models were derived to predict the SO_2 removal efficiency(RE) and energy yield(EY). Analysis of variance results showed that the packed-bed reactors(PBRs) studied were more energy efficient and had a high SO2 RE which was at least four times more than that of the non-packed reactor. Moreover, the results showed that the performance of ceramic pellets was better than that of glass pellets in PBRs. This may be due to the porous surface of ceramic pellets which allows the formation of microdischarges in the fine cavities of a porous surface when placed in a plasma discharge zone. The maximum SO_2 RE and EY were obtained at 94% and 0.81 g kWh^(-1),respectively under the optimal conditions of a concentration of gas of 750 ppm, a gas flow rate of 2lmin^(-1), and a voltage of 18 kV, which were achieved by the DBD plasma packed with ceramic pellets. Finally, the results of the model's predictions and the experiments showed good agreement.
基金supported by National Magnetic Confinement Fusion Science Programs of China(Nos.2014GB106002,2013GB114004,2011GB107000)National Natural Science Foundation of China(No.11075185)
文摘A new pellet injection system was installed on the EAST tokamak and preliminary experiments were performed during the 2012 run campaign. Typical phenomena associated with deuterium pellet injection into a plasma discharge have been observed including sudden increases of the electron density and Hα/Da emission intensity as well as a significant decrease in plasma electron temperature. Profiles have been studied in order to understand the influence of pellet fuelling on EAST discharges. Even though the injector was specifically designed for plasma fu- elling, ELM triggering using the pellet injection has also been tested. In order to find appropriate parameters for triggering ELMs in H-mode plasmas, scanning of the pellet injection speed was employed for pellets injected from both the high field side and low field side of the plasma column. It has been observed that low-speed pellets injected into H-mode plasma from the low-field side could trigger an ELM followed by a number of smaller induced ELMs at about 300 Hz.
文摘Nutrient composition of the manure of four pill millipedes （Arthrosphaera dalyi, ,4. davisoni, ,4. fumosa and,4, magna） inhabiting in semi-evergreen forests and plantations of the Western Ghats of Southwest India was evaluated. The quantity and quality of fecal pellets differed between millipedes and their habitats （forest and plantation）. Organic carbon content in manure was lower in plantations than in forests, while nitrogen content was elevated in plantations. The carbon to nitrogen （C/N） ratio of manure was lower in plantations compared to forests. The phosphorus content in manure was elevated in plantations in all except for A. dalyi. Calcium content of manure was increased in plantations than in forests. The contents of magnesium, potassium and phenolics in manure showed varied results. The mass of fecal pellets was correlated only with volume in forests （r=0.882; p 〈0.01） and pH in plantations （r=0.616; p 〈0.05）, while the volume of fecal pellets was correlated with nitrogen content in forests （r=0.751; p 〈0.01） and cal- cium in plantations （=0.619; p 〈0.05）. The conductivity was positively correlated with phosphorus and potassium, while magnesium was negatively correlated in forests as well as plantations. Potassium and magnesium were negatively correlated in forests （r=0.920; p〈0.001） and plantations （t=0.692; p 〈0.05）. Overall, the physicochemical characteristics and nutrient composition of fecal pelets differed between millipedes as well as habitats. The low carbon to nitrogen ratio and the increased nitrogen, phosphorus and calcium content in the manure of millipedes inhabiting in plantations indicates possibilities for successfully employing them for in situ composting of forest or plantation residues.
基金Natural Sciences and Engineering Research Council of Canada through Industrial Postgraduate Scholarships(NSERC-IPS)Ontario Graduate Scholarship(OGS)Ontario Power Generation(OPG)
文摘Background： Replacement of fossil fuel based energy with biochar-based bioenergy production can help reduce greenhouse gas emissions while mitigating the adverse impacts of climate change and global warming. However, the production of biochar-based bioenergy depends on a sustainable supply of biomass. Although, Northwestern Ontario has a rich and sustainable supply of woody biomass, a comprehensive life cycle cost and economic assessment of biochar-based bioenergy production technology has not been done so far in the region. Methods： In this paper, we conducted a thorough life cycle cost assessment （LCCA） of biochar-based bioenergy production and its land application under four different scenarios： 1） biochar production with low feedstock availability; 2） biochar production with high feedstock availability; 3） biochar production with low feedstock availability and its land application; and 4） biochar production with high feedstock availability and its land applicationusing SimaPro, EIOLCA software and spreadsheet modeling. Based on the LCCA results, we further conducted an economic assessment for the break-even and viability of this technology over the project period. Results： It was found that the economic viability of biochar-based bioenergy production system within the life cycle analysis system boundary based on study assumptions is directly dependent on costs of pyrolysis, feedstock processing （drying, grinding and pelletization） and collection on site and the value of total carbon offset provided by the system. Sensitivity analysis of transportation distance and different values of C offset showed that the system is profitable in case of high biomass availability within 200 km and when the cost of carbon sequestration exceeds CAD S60 per tonne of equivalent carbon （CO2e）. Conclusions： Biochar-based bioenergy system is economically viable when life cycle costs and environmental assumptions are accounted for. This study provides a medium scale slow-pyrolysis plant scenario and we recommend similar experiments with large-scale plants in order to implement the technology at industrial scale.
文摘Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for Li, Be, and B impurity pellets in reactor-relevant plasma has been derived. Results show compatibilities of lithium pellet injection used in α-particle diagnostics are positive in comparison with other solid impurity pellets (e.g. Be, B and C). Using the 2-D Kuteev lentil model, including kinetic effects, we find that currently existing pellet injection techniques will not meet core-fueling requirements for ITER-FEAT. A pressure as high as 254 MPa must be applied to a pellet accelerator with a 200 cm-long single-stage pneumatic gun, in order to accelerate a pellet with a radius rpo = 0.5 cm to a velocity of vpo, 24 × 105 cm/s penetrating 100 cm into the ITER plasma core. Comparisons of pellet velocity- and radius-dependent penetration depth between the Neutral Gas Shielding and the Kuteev's models are made. However, we find that the isotopic effects can lead to a 33% lower pellet speed for solid DT, compared to an identical H2 pellet penetrating the same length in ITER-FEAT plasma, and our calculations show that HFS injection will much improve core fueling efficiency.
文摘In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane（OCM）over titanite pervoskite is developed.The method is based on a computational fluid dynamics（CFD）code which known as Fluent may be adopted to model the reactions that take place inside the porous catalyst pellet.The steady state single pellet model is coupled with a kinetic model and the intra-pellet concentration profiles of species are provided.Subsequent to achieving this goal,a nonlinear reaction network consisting of nine catalytic reactions and one gas phase reaction as an external program is successfully implemented to CFD-code as a reaction term in solving the equations.This study is based on the experimental design which is conducted in a differential reactor with a Sn/BaTiO3 catalyst（7-8 mesh） at atmospheric pressure,GHSV of 12000 h-1,ratio of methane to oxygen of 2,and three different temperatures of 1023,1048 and 1073 K.The modeling results such as selectivity and conversion at the pellet exit are in good agreement with the experimental data.Therefore,it is suggested that to achieve high yield in OCM process the modeling of the single pellet should be considered as the heart of catalytic fixed bed reactor.
基金supported by the NIFS budget code ULPP021,the Ministry of Education Science,Sports and CultureGrant-in-Aid for Scientific Research(B)23340184partially supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics(No.11261140328)
文摘The deposition profile of the impurity pellet is measured by a two-dimensional fast- framing vacuum ultraviolet （VUV） camera system in the large helical device （LHD）. The fast framing camera selectively measures the emission from the hydrogen-like ions of carbon （C VI） with a frame rate of several kHz. From the emission profile of the hydrogen-like carbon ions, which are in the process of ionization, the initial deposition profile of the carbon is estimated using a simple one-dimensional transport model.
基金Financial support from the National Basic Research Program of China(973 Program,2010CB736203)
文摘The diffusion and reaction phenomenon in a Fe-based catalyst pellet for Fischer-Tropsch synthesis was studied. It was considered that the pores of catalyst pellets were full of liquid wax under Fischer-Tropsch synthesis conditions. The re- actants diffused from the bulk gas phase to the external surface of the pellet, and then the reactants diffused through the wax inside the pellet and reacted on the internal surface formed along the pore passages of the pellet. On the basis of reaction kinetics and double a-ASF product distribution model, a diffusion and reaction model of catalyst pellet was established. The effects of diffusion and reaction interaction in a catalyst pellet, the bulk temperature, the reaction pressure and the pellet size on the reactivity were further investigated. The relationship between the internal diffusion effectiveness factor of spherical catalyst pellet and the Thiele modulus were also discussed. The bulk temperature and pellet size have significant effects on the reactivity, while the pressure shows only a slight influence on the reactivity. The internal diffusion effectiveness factor decreases with an increasing Thiele modulus.
文摘A measuring system for high-speed hydrogen ice pellet was introduced in this paper and the photographing of flying pellet taken therein. With the system, a pellet (minimum size of φ 0.3 mm) velocity (ranging from 50 m/s to 2500 m/s) can be measured in the HL-1M tokamak fueling experiments. By analyzing photographs and the conditions of frozen pellets (including gas supply, gas replenishment, temperature controlling etc), the pellet-freezing technology is summarized in the paper.
基金the National Key R&D Program of China under Grant Nos.2017YFE0301100 and 2019YFE03030004the National Natural Science Foundation of China under Grant No.11575039Users with Excellence Program of Hefei Science Center CAS(2020HSCUE010)。
文摘To understand the effect of injected deuterium(D)pellets on background plasma,the ablation of D pellets and the transport of D species in both atomic and ionic states in the EAST device are simulated using a modified dynamic neutral gas shield model combined with the edge plasma code SOLPS-ITER.The simulation results show that there is a phenomenon of obvious atomic deposition in the scrape-off layer(SOL)after pellet injection,which depends strongly on the injection velocity.With increasing injection velocity,the atomic density in the SOL decreases evidently and the deposition time is relatively shortened.Possible effects for triggering of edge localized modes(ELMs)by D and Li pellets are also discussed.With the same pellet size and injection velocity,the maximum perturbation pressure caused by D pellets is obviously higher.It is found that the resulting maximum perturbed pressure is remarkably enhanced when the injection velocity is reduced from 300 m/s to 100 m/s for a pellet with a cross section of 1.6 mm,which indicates that the injection velocity is important for ELM pacing.This work can provide reasonable guidance for choosing pellet parameters for fueling and ELM triggering.
基金supported by the National MCF Energy R&D Program of China(No.2019YFE03010004)the National Key R&D Program of China(Nos.2018YFE0309100 and 2017YFE0302000)+1 种基金the National Magnetic Conflnement Fusion Science Program(Nos.2015GB111002 and 2015GB104000)National Natural Science Foundation of China(Nos.11775089,11905077,51821005 and 11575068)。
文摘Pellet injection is an attractive technology for core-fueling and magnetohydrodynamic study in magnetic-conflnement fusion devices like tokamaks and stellarators.It can inject solid hydrogen/deuterium pellets into the plasma with deeper density deposition compared with other fueling methods,such as gas pufflng.A three-barrel H_(2)pellet injection system was installed on the J-TEXT tokamak and experiments were carried out.The pellets are formed in three barrels cooled by a cryocooler and compressor system at around 9 K,and are 0.8 mm/1 mm diameter and 0.8 mm length.The pellet is launched by helium propellant gas and injected from the lowfleld side of the plasma.The normal range of pellet speed is 210–310 m s^(-1)for different propellant gas pressures.Due to the three-barrel structure,the number of injected pellets can be adjusted between one and three.Pellets can be launched sequentially with arbitrary time intervals,which enables flexible applications.The results of the experiments show that pellet fueling efflciency can reach 50%.The energy conflnement time increased by about 7.5–10 ms after pellet injection.
文摘An Ha emission measurement array with 25 detection channels has been built on HL-1M tokamak. Reconstruction maps of Ha emission distribution in plasma cross-section have been obtained by using tomography, with a hydrogen pellet injected into the plasma. The dimension, the shape and the rotation characteristic of the cross-section of the pellet ablation material flow tube have been observed. These results have been analysed and explained tentatively by using the ‘tail＇ model and the linear expansion model.
基金supported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, and the Low Carbon Scholarship for SIIT Graduate Students
文摘Scalings of the density peak and pellet penetration length in ITER are developed based on simulations using 1.5D BALDUR integrated predictive modeling code. In these simulations, the pellet ablation is described by the Neutral Gas Shielding （NGS） model with grad-B drift effect taken into account. The NGS pellet model is coupled with a plasma core transport model, which is a combination of an MMM95 anomalous transport model and an NCLASS neoclassical transport model. The BALDUR code with a combination of MMM95 and NCLASS models, together with the NGS model, is used to simulate the time evolution of plasma current, ion and electron temperatures, and density profiles for ITER standard type I ELMy H-mode discharges during the pellet injection. As a result, the scaling of the density peak and pellet penetration length at peak density can be established using this set of predictive simulations that covers a wide range of ITER plasma conditions and pellet parameters. The multiple regression technique is utilized in the development of the scalings. It is found that the scaling for density at center is sensitive to both the plasma and pellet parameters; whereas the scalings for density and location of the additional peak are sensitive to the pellet parameters only.
文摘The preliminary design of a multi-barrels pellet injector with cycle refrigerator as an advanced plasma-fuelling tool for HL-2A tokamak has been proposed. The design aims at precise temperature control, easy operation with high reliability and high flexibility. GM-cycle refrigerator and pipe-gun structure have been employed to produce 25 pellets in 25 gun barrels simultaneously and the design aims. have been accomplished. Prime design principle, engineering parameters, structure and layout of the cryostat components as well as calculation of heat load for the cryostat are presented.
文摘Pneumatic and centrifugal injectors for steady-state plasma refuelling bysolid hydrogen, deuterium and tritium pellets have been designed at the PELIN Laboratory to meetrequirements of LHD, TORE SUPRA, and ITER. Presented here is a review of these injectors' designsand results.
