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Particuology 2013年第6期11卷 681-688页

作者： D.T.k.Dora S.R.Panda Y.k.Mohanty g.k.roy Department of Chemical Engineering Gandhi Institute of Engineering and Technology(GIET) Department of Chemical Engineering National Institute of Technology(NIT)

Hydrodynamic characteristics of fluidization in a conical or tapered bed differ from those in a columnar bed because the superficial velocity in the bed varies in the axial direction. Fixed and fluidized regions could coexist and sharp variations in pressure drop could occur, thereby giving rise to a noticeable pressure drop-flow rate hysteresis loop under incipient fluidization conditions. To explore these unique properties, several experiments were carried out using homogeneous, well-mixed, ternary mixtures with three dif- ferent particle sizes at varying composition in gas-solid conical fluidized beds with varying cone angles. The hydrodynamic characteristics determined include the minimum fluidization velocity, bed fluctuation, and bed expansion ratios. The dependence of these quantities on average particle diameter, mass fraction of the fines in the mixture, initial static bed height, and cone angle is discussed. Based on dimensional analysis and factorial design, correlations are developed using the system parameters, i.e. geometry of the bed （cone angle）, particle diameter, initial static bed height, density of the solid, and superficial velocity of the fluidizing medium. Experimental values of minimum fluidization velocity, bed fluctuation, and bed expansion ratios were found to agree well with the developed correlations.

关键词： gas-solid fluidization Conical bed Homogeneous ternary mixtures Bed fluctuation ratio Bed expansion ratio

Statistical modeling and optimization of a multistage gas-solid fluidized bed for removing pollutants from flue gases

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Particuology 2015年第5期13卷 72-81页

作者： k.Mahalik Y.k.Mohanty k.C.Biswal g.k.roy J.N.Sahu Department of Chemical Engineering Gandhi Institute of Engineering and Technology Department of Chemical Engineering National Institute of Technology Department of Chemical Engineering Faculty of EngineeringUniversity of Malaya Petroleum and Chemical Engineering Programme Area Faculty of EngineeringInstitut Teknologi Brunei(A Technology University)

The present paper describes the statistical modeling and optimization of a multistage gas-solid fluidized bed reactor for the control of hazardous pollutants in flue gas. In this work, we study the hydrodynamics of the pressure drop and minimum fluidization velocity. The hydrodynamics of a three-stage fluidized bed are then compared with those for a single-stage unit. It is observed that the total pressure drop over all stages of the three-stage fluidized bed is less than that of an identical single-stage system. However, the minimum fluidization velocity is higher in the single-stage unit. Under identical conditions, the minimum fluidization velocity is highest in the top bed, and lowest in the bottom bed. This signifies that the behavior of solids changes from a well-mixed flow to a plug-flow, with intermediate behavior in the middle bed.

关键词： Fluidized bed Multi-stage Pressure drop Minimum fluidization velocity Optimization

Hydrodynamics of three-phase fluidization of homogeneous ternary mixture in a conical conduit-Experimental and statistical analysis

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Chinese Journal of Chemical Engineering 2016年第10期24卷 1335-1343页

作者： R.k.Padhi D.T.k.Dora Y.k.Mohanty g.k.roy B.Sarangi Department of Chemical Engineering GIETGunupur-765 022RayagadaOdishaIndia Department of metallurgical Engineering ICITSarangaDhenkanalOdishaIndia

Hydrodynamics of conical fluidized bed differ from that of columnar beds by the fact that a velocity gradient exists along the axial direction of the *** gas–liquid–solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase *** a device is of considerable industrial importance as evident from its wide applications in chemical,refining,petrochemical,biochemical processing,pharmaceutical and food *** explore this,a series of experiments have been carried out for homogeneous well-mixed ternary mixtures of dolomite of varying compositions in a three-phase conical fluidized *** hydrodynamic characteristics determined included the bed pressure drop,bed fluctuation and bed expansion *** single and combined effects of operating parameters such as superficial gas velocity,superficial liquid velocity,initial static bed height,average particle size and cone angle on the responses have been analyzed using response surface methodology(RSM).A 25 full factorial central composite experimental design has been *** of variance(ANOVA) showed a high coefficient of determination value and satisfactory prediction second-order regression models have been *** values of bed pressure drop,bed fluctuation and bed expansion ratios have been found to agree well with the developed correlations.

关键词： gas-liquid-solid fluidization Conical bed Bed pressure drop Bed fluctuation ratio and bed expansion ratio ANOVA

kinetics of thermal decomposition of hydrated minerals associated with hematite ore in a fluidized bed reactor

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International Journal of Minerals,Metallurgy and Materials 2017年第3期24卷 229-239页

作者： P.C. Beuria S.k. Biswal B.k. Mishra g.g. roy Institute of Minerals and Materials Technology Council of Scientific & Industrial Research Bhubaneswar-751013 India Indian Institute of Technology Kharagpur-721302 India

The kinetics of removal of loss on ignition(LOI) by thermal decomposition of hydrated minerals present in natural iron ores(i.e.,kaolinite,gibbsite,and goethite) was investigated in a laboratory-scale vertical fluidized bed reactor(FBR) using isothermal methods of kinetic *** in the FBR in batch processes were carried out at different temperatures(300 to 1200°C) and residence time(1 to 30 min) for four different iron ore samples with various LOIs(2.34wt% to 9.83wt%).The operating velocity was maintained in the range from 1.2 to 1.4 times the minimum fluidization velocity(Umf).We observed that,below a certain critical temperature,the FBR did not effectively reduce the LOI to a desired level even with increased residence *** results of this study indicate that the LOI level could be reduced by 90% within 1 min of residence time at 1100°*** kinetics for low-LOI samples(kinetics is characterized by a lower activation energy(diffusion-controlled physical moisture removal),followed by a higher activation energy(chemically controlled removal of LOI).In the case of high-LOI samples,three different kinetics mechanisms prevail at different temperature *** temperature up to 450°C,diffusion kinetics prevails(removal of physical moisture);at temperature from 450 to 650°C,chemical kinetics dominates during removal of matrix *** temperatures greater than 650°C,nucleation and growth begins to influence the rate of removal of LOI.

关键词： thermal decomposition fluidized beds kinetic analysis hydrated iron ore activation energy

Study on kinetics of thermal decomposition of low LOI goethetic hematite iron ore

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International Journal of Mining Science and Technology 2017年第6期27卷 1031-1036页

作者： Beuria P.C. Biswal S.k. Mishra B.k. roy g.g. Mineral Processing Department CSIR–Institute of Minerals and Materials TechnologyBhubaneswar 751013India Indian Institute of Technology Kharagpur 721302India

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 *** 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.

关键词： Loss on ignition goethite kaolinite gibbsite Roasting Pellet feed kinetic analysis

Effect of promoters on dynamics of gas-solid fluidized bed——Statistical and ANN approaches

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China Particuology 2007年第6期5卷 401-407页

作者： Y.k. Mohanty k.C. Biswal g.k. roy B.P. Mohanty Department of Chemical Engineering GIET Gunupur 765 022 Rayagada Orissa India Department of Chemical Engineering NIT Rourkela 769008 Orissa India

In this study, a bubbling fluidized bed column, 99 mm in inside diameter and 960 mm in height, was used to investigate the effect of rod and disc promoters on fluctuation and expansion ratios. Factorial design （statistical approach） and artificial neural network （ANN） models were developed to predict the fluctuation and expansion ratios in this gas-solid fluidized bed with varying gas flow rates, bed heights, particle sizes and densities. The fluctuation and expansion predicted using these statistical and ANN models, for beds with and without promoters, were found to agree well with corresponding experiments. The statistical model was found to be superior to the ANN model due to its ability to take into account both individual and interactive effects. The rod promoters were found to be more effective in reducing bed fluctuation, and in increasing bed expansion at high gas mass velocities.

关键词： gas-solid fluidized bed Fluctuation ratio Expansion ratio Promoter Factorial design Artificial neural network

Practice patterns among ophthalmic surgeons in treating concomitant oculoplastic conditions in preoperative period:A questionnaire-based study

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World Journal of Clinical Cases 2025年第1期13卷 29-37页

作者： Bijnya Birajita Panda Chitaranjan Mishra Bhagabat Nayak Avik kumar roy Logesh Balakrishnan Priyadarshini Mishra Department of Ophthalmology All India Institute of Medical SciencesBhubaneswar 751019OdishaIndia Department of Vitreo-Retina Trilochan NetralayaSambalpur 768004India Department of glaucoma Services LV Prasad Eye InstituteBhubaneswar 751013India Department of Statistics Apollo HospitalsChennai 823104India

BACkgROUND Addressing oculoplastic conditions in the preoperative period ensures both the safety and functional success of any ophthalmic *** oculoplastic conditions,like nasolacrimal duct obstruction,have been extensively studied,whereas others,like eyelid malposition and thyroid eye disease,have received minimal or no *** To investigate the current practice patterns among ophthalmologists while treating concomitant oculoplastic conditions before any subspecialty ophthalmic *** A cross-sectional survey was disseminated among ophthalmologists all over *** survey included questions related to pre-operative evaluation,anaesthetic and surgical techniques preferred,post-operative care,the use of adjunctive therapies,and patient follow-up *** A total of 180 ophthalmologists responded to the *** practitioners(89%)felt that the ROPLAS test was sufficient during pre-operative evaluation before any subspecialty surgery was *** most common surgical techniques employed were lacrimal drainage procedures(Dacryocystorhinostomy)(63.3%),eyelid malposition repair(36.9%),and ptosis repair(58.7%).Post-operatively,47.7%of respondents emphasized that at least a 4-week gap should be maintained after lacrimal drainage procedures and eyelid ***-seven percent of ophthalmologists felt that topical anaesthetic procedures should be preferred while performing ocular surgeries in thyroid eye disease *** Approximately 50%of ophthalmologists handle prevalent oculoplastic issues themselves,seeking the expertise of an oculoplastic surgeon under particular *** ophthalmologists still favor using ROPLAS as a preliminary screening method before proceeding with cataract *** conditions and thyroid eye disease are not as commonly addressed before subspecialty procedures compared to issues like nasolacrimal duct obstruction and periocular infections.

关键词： Oculoplasty Ophthalmic plastic surgery Nasolacrimal duct obstruction Practice patterns Survey

Bed dynamics of gas-solid fluidized bed with rod promoter

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China Particuology 2007年第4期5卷 261-266页

作者： Awadhesh kumar gopendra k.roy Department of Civil Engineering National Institute of TechnologyRourkela 769008OrissaIndia Department of Chemical Engineering National Institute of TechnologyRourkela 769008OrissaIndia

The dynamic characteristics of a gas-solid fluidized bed with different rod promoters have been investigated in terms of bed expansion and fluctuation, minimum fluidization velocity and distributor-to-bed pressure drop ratio at minimum fluidization velocity. Experimentation based on statistical design has been carried out and model equations using factorial design of experiments have been developed for the above mentioned quantities for a promoted gas-solid fluidized bed. The model equations have been tested with additional experimental data. The system variables include four types of rod promoters of varying blockage volume, bed particles of four sizes and four initial static bed heights. A comparison between the predicted values of the output variables using the proposed model equation with their corresponding experimental ones shows fairly good agreement.

关键词： Dynamic characteristics Statistical design gas-solid fluidization Rod promoter

Recent Progress and Approaches on Carbon-Free Energy from Water Splitting

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Nano-Micro Letters 2019年第4期11卷 791-816页

作者： Aslam Hossain k.Sakthipandi A.k.M.Atique Ullah Sanjay roy Department of Physical and Inorganic Chemistry Institute of Natural Science and MathematicsUral Federal UniversityYekaterinburgRussia Department of Physics Sethu Institute of TechnologyKariapattiTamil Nadu 626115India Nanoscience and Technology Research Laboratory Atomic Energy CentreBangladesh Atomic Energy CommissionDhaka 1000Bangladesh Department of Chemistry Shibpur Dinobundhoo Institution(College)HowrahWest Bengal 711102India

Sunlight is the most abundant renewable energy resource,providing the earth with enough power that is capable of taking care of all of humanity’s desires-a hundred times ***,as it is at times diffuse and intermittent,it raises issues concerning how best to reap this energy and store it for times when the Sun is not *** increasing population in the world and modern economic development,there will be an additional increase in energy *** that use daylight to separate water into individual chemical elements may well be the answer to this issue,as water splitting produces an ideal *** such devices that generate fuel were to become widely adopted,they must be low in cost,both for supplying and ***,it is essential to research for cheap technologies for water *** review summarizes the progress made toward such development,the open challenges existing,and the approaches undertaken to generate carbon-free energy through water splitting.

关键词： Water splitting Renewable energy sources Hydrogen generation Photocatalysis Nanostructure

In silico designing of power conversion efficient organic lead dyes for solar cells using todays innovative approaches to assure renewable energy for future

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npj Computational Materials 2017年第1期3卷 263-274页

作者： Supratik kar Juganta k.roy Jerzy Leszczynski Interdisciplinary Center for Nanotoxicity Department of Chemistry and BiochemistryJackson State UniversityJacksonMS 39217USA

Advances in solar cell technology require designing of new organic dye sensitizers for dye-sensitized solar cells with high power conversion efficiency to circumvent the disadvantages of silicon-based solar *** silico studies including quantitative structureproperty relationship analysis combined with quantum chemical analysis were employed to understand the primary electron transfer mechanism and photo-physical properties of 273 arylamine organic dyes from 11 diverse chemical families explicit to iodine *** direct quantitative structure-property relationship models enable identification of the essential electronic and structural attributes necessary for quantifying the molecular prerequisites of 11 classes of arylamine organic dyes,responsible for high power conversion efficiency of dye-sensitized solar ***,N,N′-dialkylaniline and indoline have been least explored classes under arylamine organic dyes for dye-sensitized solar ***,the identified properties from the corresponding quantitative structure-property relationship models of the mentioned classes were employed in designing of“lead dyes”.Followed by,a series of electrochemical and photo-physical parameters were computed for designed dyes to check the required variables for electron flow of dye-sensitized solar *** combined computational techniques yielded seven promising lead dyes each for all three chemical classes ***(130,183,and 46%)increment in predicted %power conversion efficiency was observed comparing with the existing dye with highest experimental %power conversion efficiency value for tetrahydroquinoline,N,N′-dialkylaniline and indoline,respectively maintaining required electrochemical parameters.

关键词： designing dye aniline