Chemical Engineering Group

Pilāni, India

Chemical Engineering Group

Pilāni, India
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Purohit R.D.,Chemical Engineering Group | Nair S.R.,Chemical Engineering Group | Prakash D.,Chemical Engineering Group | Sinha P.K.,Chemical Engineering Group | And 5 more authors.
Journal of Physics: Conference Series | Year: 2010

In order to realize SOFC as power generating devices, multiple cells are connected in series through an interconnect material to accumulate the voltage output. The interconnect should have very low permeability for the gases used. A novel solution combustion process has been developed for producing the phase pure, well-sinterable powders of Ca-doped LaCrO3 interconnect material. A process has been developed to produce the coarse granules as a feed material using combustion-synthesized powder for plasma spray through (a) preparation of granules through cold iso-static pressing followed by breaking and sieving (b) sintering of the green granules followed by sieving. The flow ability and deposition efficiency studies on 75 and 75-125 μm powders suggested that 75 powder is more suitable for the plasma spray coating. The plasma process parameters; plasma power, flow rate of carrier gases and distance between substrate and plasma gun have been optimized to achieve required coating characteristics. The as-produced coating using 20 kW power plasma gun on the porous Sr-doped LaMnO3 cathode substrates has been examined by SEM. An adherent coating of about 100 μm has been observed in the micrographs. No large cracks were observed throughout the coating. However, the coating was not found to be impervious in nature. Also the micrographs showed incomplete melting of the plasma-coated material. The similar experiments were performed using a higher power ( 60 Kw) plasma gun. The coated coupons were tested for leakage by checking water penetration. It was found that water did not penetrate for quite a long time. Therefore, the coupon was further tested for leakage by keeping it over a port connected to vacuum pump. The vacuum attained was 7×10-3 mbar and it was maintained for four consecutive days. The SEM studies on the coated sample showed a quite dense coating along with a very few small local pores. © 2010 IOP Publishing Ltd.


Mohanta H.K.,Chemical Engineering Group | Gupta R.K.,ICFAI University, Tripura
International Journal of Automation and Control | Year: 2010

This paper presents an online implementation of wavelet-based least-square identification (WLSI) and wavelet-based dynamic matrix control (WDMC) in a plate-type heat exchanger unit. Wavelet domain 'blocking' and 'condensing' (B&C) techniques are used to reduce the computation time for optimisation of dynamic matrix control (DMC) performance index. Algorithms for WLSI and WDMC are developed and implemented in the online identification and control of temperature in a heat exchanger unit. The results are compared with conventional PID and DMC controllers. It is observed that the WDMC is better and robust than the other controllers. © 2010 Inderscience Enterprises Ltd.


Ummadisingu A.,Chemical Engineering Group | Sheth P.,Faculty Division 1 | Babu B.V.,Birla Institute of Technology and Science
10AIChE - 2010 AIChE Annual Meeting, Conference Proceedings | Year: 2010

Biomass is the oldest form of energy used by human beings, mainly in the form of wood. It is a renewable source of energy and has many advantages from an ecological point of view. The direct combustion of biomass generates concern among environmentalists, as it is incomplete and inconsistent and may produce organic particulate matter, carbon monoxide and other organic gases. Biomass gasification has attracted the greatest interest as it offers a higher efficiency as compared to combustion and pyrolysis. Gasification is the process of conversion of solid carbonaceous fuel into combustible gas by partial combustion. Various groups of researchers have carried out experimental studies on downdraft biomass gasifier with different biomass materials such as wood, wood chips, hazelnut shell, agricultural wastes, saw dust, etc. It is reported that bridging is a normal occurrence in the gasifier. It occurs mainly in the pyrolysis zone of the downdraft biomass gasifier. In the present study, wood shavings of pine wood are used as biomass in a downdraft biomass gasifier. To overcome bridging, the design of the biomass gasifier is modified by incorporating a shaking mechanism. With this modified design of the biomass gasifier, experiments are carried out with pine wood (Pinus roxburghii) shavings as biomass covering wide range of operating conditions. The performance of the biomass gasifier system is evaluated in terms of equivalence ratio, producer gas composition, calorific value of the producer gas, gas production rate, zone temperatures and cold gas efficiency.


Mollekopf N.,TU Dresden | Treppe K.,TU Dresden | Fiala P.,TU Dresden | Dixit O.,Chemical Engineering Group
Chemie-Ingenieur-Technik | Year: 2011

The study focuses on the vacuum microwave treatment of low-moisture potato starch. Typical temperature and drying profiles are presented and explained with the help of other process parameters such as sample weight, pressure, incident and absorbed microwave power. Subsequently water absorption capacity of vacuum microwave treated and conduction heated samples was investigated at 55°C. During vacuum microwave treatment, 50 g samples were treated with incident powers of 460, 500 and 750 W at 3800 Pa for durations between 30 and 300 s. Water absorption capacity increased exponentially with the net absorbed energy but could not be functionally correlated to end temperature and incident power. During conduction heating, starch samples were treated at temperature values of 120, 130, 140, 150 and 160°C, till constant weight. The water absorption capacity was observed to increase with increase in treatment temperature. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Sheth P.N.,Birla Institute of Technology and Science | Sheth P.N.,Chemical Engineering Group | Amita U.,Birla Institute of Technology and Science | Amita U.,Chemical Engineering Group | Babuc B.V.,Birla Institute of Technology and Science
10AIChE - 2010 AIChE Annual Meeting, Conference Proceedings | Year: 2010

Kinetics-free equilibrium models can predict the exit gas composition of the biomass gasifier, given the solid composition and the equilibrium temperature, but they cannot be used for reactor design. Hence, there is a need to develop a combined transport and kinetic model which takes into account of the kinetics of homogeneous and heterogeneous chemical reactions, transport of volatiles produced, heat and mass transfer between solid and gaseous phase and pyrolysis reactions. Taking into account of the importance of downdraft biomass gasifier and its commercial applications, it is essential to have a complete model for such a configuration. In the present study, a transient onedimensional model is developed for the throated close-top downdraft biomass gasifier. The model takes into account of the drying, pyrolysis, secondary tar reactions, homogeneous gas reactions and heterogeneous combustion/gasification reactions. The experimental data obtained in our earlier study are used to validate the simulation results of the complete combined transport and kinetic model. The fraction of initial moisture content, air flow rate, temperature of the drying & pyrolysis zone, and chemical composition of the biomass are required as input data for the model to predict the composition of producer gas. The variation of molar fraction of producer gas components with time is predicted and compared with the experimental data. It is concluded from the present study that the developed model can predict the performance of the biomass gasifier, a priori. The results of this study are also useful in the design of a downdraft biomass gasifier.


Ummadisingu A.,Chemical Engineering Group | Ummadisingu A.,Birla Institute of Technology and Science | Sheth P.,Chemical Engineering Group | Sheth P.,Birla Institute of Technology and Science | And 2 more authors.
AIChE Annual Meeting, Conference Proceedings | Year: 2010

Biomass is the oldest form of energy used by human beings, mainly in the form of wood. It is a renewable source of energy and has many advantages from an ecological point of view. The direct combustion of biomass generates concern among environmentalists, as it is incomplete and inconsistent and may produce organic particulate matter, carbon monoxide and other organic gases. Biomass gasification has attracted the greatest interest as it offers a higher efficiency as compared to combustion and pyrolysis. Gasification is the process of conversion of solid carbonaceous fuel into combustible gas by partial combustion. Various groups of researchers have carried out experimental studies on downdraft biomass gasifier with different biomass materials such as wood, wood chips, hazelnut shell, agricultural wastes, saw dust, etc. It is reported that bridging is a normal occurrence in the gasifier. It occurs mainly in the pyrolysis zone of the downdraft biomass gasifier. In the present study, wood shavings of pine wood are used as biomass in a downdraft biomass gasifier. To overcome bridging, the design of the biomass gasifier is modified by incorporating a shaking mechanism. With this modified design of the biomass gasifier, experiments are carried out with pine wood (Pinus roxburghii) shavings as biomass covering wide range of operating conditions. The performance of the biomass gasifier system is evaluated in terms of equivalence ratio, producer gas composition, calorific value of the producer gas, gas production rate, zone temperatures and cold gas efficiency.


Atribak I.,University of Alicante | Bueno-Lopez A.,University of Alicante | Garcia-Garcia A.,University of Alicante | Navarro P.,Chemical Engineering Group | And 2 more authors.
Applied Catalysis B: Environmental | Year: 2010

Birnessite and cryptomelane samples have been prepared and characterised by N2 adsorption at -196 °C, XRD, XRF, XPS and H2-TPR. The activity of birnessite and cryptomelane for catalysed combustion of soot under NOx/O2 gas mixtures has been studied and compared with that of some other commercially available pure manganese oxides, namely MnO, MnO2, Mn2O3, Mn3O4, and natural MnO2. Birnessite and cryptomelane are more active for soot combustion than all the commercial oxides tested. Among the manganese oxides studied, birnessite shows the highest catalytic activity, lowering the soot combustion temperature by 150 °C regarding the uncatalysed reaction, and cryptomelane lowers this temperature by 120 °C. The NOx removal profiles suggest that birnessite chemisorbs NOx and forms potassium nitrate, which melts and reacts with soot. On the contrary, the main soot combustion pathway for cryptomelane and for the commercial manganese oxide tested is based on the catalytic oxidation of NO to NO2. Birnessite and cryptomelane only yield CO2 as carbon-containing soot combustion product. © 2009 Elsevier B.V. All rights reserved.


Patwardhan K.V.,Chemical Engineering Group | Rajyalakshmi S.,Chemical Engineering Group | Balaramakrishna P.,Chemical Engineering Group
Petroleum Technology Quarterly | Year: 2013

Stringent emission control legislations and a well-informed market have compelled refiners to build highly complex refineries for producing cleaner and more efficient fuels. With crude slates getting heavier and sour, the demand for hydrogen is rapidly increasing and refiners are looking into new reforming technologies and schemes for optimum hydrogen production. A discussion covers a mathematical model developed for a greater understanding of the functioning of gas heating reforming; a simulation model developed to optimize the performance of a steam methane reforming/autothermal reforming + gas heating reforming combination; increased hydrogen demand; process scheme; parametric analysis; and synthesis gas composition.

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