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Heat Transfer and Thermographic Analysis of Catalyst Surface during Multiphase Phenomena under Spray-Pulsed Conditions for Dehydrogenation of Cyclohexane over Pt Catalysts
Get PDFDehydrogenation of cyclohexane over Pt/alumite and Pt/activated carbon catalysts has been carried out for
hydrogen storage and supply to fuel cell applications. An unsteady state has been created using spray pulsed
injection of cyclohexane over the catalyst surface to facilitate the endothermic reaction to occur efficiently.
Higher temperature of the catalyst surface is more favorable for the reaction, thus the heat transfer phenomena
and temperature profile under alternate wet and dry conditions created using spray pulsed injection becomes
important. IR thermography has been used for monitoring of temperature profile of the catalyst surface simultaneously with product analysis. The heat flux from the plate-type heater to the catalyst has been estimated using a rapid temperature recording and thermocouple arrangement. The estimated heat flux under transient conditions was in the range of 10-15 kW/m2, which equates the requirement for endothermic reactions to the injection frequency of 0.5 Hz, as used in this study. The analysis of temperature profiles, reaction products over two different supports namely activated carbon cloth and alumite, reveals that the more conductive support such as alumite is more suitable for dehydrogenation of cyclohexane
Use of multiple regression analysis for predicting trihalomethane formation in water supply
No full textTrihalomethanes represent between 5 & 20% of the total chlorinated products formed during the chlorination process in water treatment. Trihalomethanes are carcinogenic in nature and consequently their presence in drinking water has raised much concern both at national and international levels. The water quality data was collecte for Mumbai water supply for the concentrations of individual species of Trihalomethanes, chloroform, bromodichloromethan and bromoform in finished water at the outlet of treatment process and master balancing reservoir. A multiple regrassion model for chloroform formation with respect to pH, turbidity and total organic carbon was generated for predicting trihalomethane in the finished water at the outlet before laving the treatment plant for the consumers using the data of Panjrapur, Bhandup, Tulsiand and Verar treatment plants. In general this model was found to give acceptable fits
Photocatalytic degradation of 3-nitrobenzenesulfonic acid in aqueous TiO2 suspensions
No full textThe photocatalytic degradation of 3-nitrobenzenesulfonic acid in the presence of solar radiation and artificial UV radiation with suspended TiO2 was studied in a batch and continuous annular reactor,respectively. The effects of catalyst loading, pH, presence of anions and cations and initial concentration on the rate of photocatalytic degradation were investigated. Concentration–time data were correlated with the rate equation d[Ct=0]/dt = krK[Ct=0]/(1 + K[Ct=0]). Studies were carried out to compare the photolytic,photochemical and photocatalytic methods of degradation
Kinetic analysis of treatment of textile wastewater in hybrid column upflow anaerobic fixed bed reactor
No full textTreatment of textilewastewater is considered to be difficult by traditional systems. The present study is related to treatment of textilewastewater in
an anaerobic reactor. The study showed the effectiveness of biological treatment of wastewater involving appropriate microorganism and suitable
support media in a hybrid column, upflow anaerobic fixed bed (UAFB) reactor. COD and color were reduced to 84.80%, and 90% for textile
wastewater. The reactor was operated at 1.038–8.21 g CODm−3 d−1 of loading and found that 81.58% COD and 86.22% color removal at the
highest loading rate. At steady state under anaerobic condition, colorwas effectively removed. Biokinetic models were applied to data obtained from
experimental studies in UAFB reactor. Treatment efficiencies of the reactor were investigated at different hydraulic retention times (9.6–23.76 h)
and organic loading rates (1.038–8.21 g CODm−3 d−1). Second-order and a Stover–Kincannon models were best fitted to the hybrid column reactor.
The second-order substrate removal rate constant (k2(S)) was found as 10.50 h−1 for UAFB. Applying the modified Stover–Kincannon model to the
UAFB reactor, the maximum removal rate constant (Umax) and saturation value constant (KB) were found to be 31.69 and 45.37 g d−1, respectivel
Heat Transfer and Thermographic Analysis of Catalyst Surface during Multiphase Phenomena under Spray-Pulsed Conditions for Dehydrogenation of Cyclohexane over Pt Catalysts
No full textDehydrogenation of cyclohexane over Pt/alumite and Pt/activated carbon catalysts has been carried out for
hydrogen storage and supply to fuel cell applications. An unsteady state has been created using spray pulsed
injection of cyclohexane over the catalyst surface to facilitate the endothermic reaction to occur efficiently.
Higher temperature of the catalyst surface is more favorable for the reaction, thus the heat transfer phenomena
and temperature profile under alternate wet and dry conditions created using spray pulsed injection becomes
important. IR thermography has been used for monitoring of temperature profile of the catalyst surface
simultaneously with product analysis. The heat flux from the plate-type heater to the catalyst has been estimated
using a rapid temperature recording and thermocouple arrangement. The estimated heat flux under transient
conditions was in the range of 10-15 kW/m2, which equates the requirement for endothermic reactions to
the injection frequency of 0.5 Hz, as used in this study. The analysis of temperature profiles, reaction products
over two different supports namely activated carbon cloth and alumite, reveals that the more conductive
support such as alumite is more suitable for dehydrogenation of cyclohexane
Fly ash based zeolite analogues: versatile materials for energy and environment conservation
No full textFly ash is combustion residue from burning of pulverised coal in electric utility generating stations. The annual production of fly
ash in India is around 100 MTPA and is responsible for several environmental hazards, which is quite well documented. There are
stringent norms for its land disposal and hence utilisation of fly ash is imperative. Fly ash has more than 85% of SiO2 and Al2O3
content and is therefore a tailor made raw material for production of zeolite. An innovative process has been developed for
synthesis of zeolites using fly ash as a substitute for conventional raw materials viz. sodium silicate and aluminate. The process
consists of three major steps viz. fusion of caustic soda and fly ash for optimal extraction of silicate and aluminate, aging step which
provides time for formation of nuclei and hydrothermal crystallization resulting in activation of nuclei into well defined crystals.
Low temperature operation, simplicity of process and optimal recycling of unused reactants and process water are special features
of these processes. Zeolites have high internal and external surface areas and also exhibit high exchange capacities, which makes
them versatile materials for targeting wide range of pollutants, ranging from cationic to anionic and hydrophilic to hydrophobic
molecules. The major uses of zeolites are in adsorption, ion exchange and as catalysts. The use of zeolites in environmental
remediation is restricted due to procurement problem and prohibitive cost, which can be overcome by using low cost fly ash based
zeolites (FAZs). The synthesis of FAZ-A and FAZ-Y and their modifications either by transition metal incorporation or by
surfactant treatment for various environmental applications in air, water and soil remediation are addressed in this review
Quantitative assessment of annual runoff in sub-cattchment using GIS : A case study of the Tapi river, India
No full textVolatile organic carbon monitoring in indoor environment using a versatile hydrophobic flyash-based zeolite as adsorbent
No full textVolatile organic carbon (VOC) in indoor air is a matter of concern. The conventional adsorbents used for monitoring of VOC's are beset with drawbacks. A new class materials,namely surface modified zeolites (SMZ) has been synthesized from flyash as the source material. SMZ have been used for indoor monitoring of VOCs vis-a-vis conventional adsorbents. The adsorbed VOCs were desorbed at higher temperature and analysed using GC-MS Technique. Thr VOC adsorbed on SMZ are much higher compaired to activated carbon, illustrating the successful usage oF SMZ as novel and versatile adsorbent for VOC monitoring
