Department of Chemical Engineering
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Item Advances in Downdraft Biomass Gasification( Nova Science Publishers, 2010) Sheth, P.N.Item Power Generation from Biomass Gasification: A Renewable Energy Source based Technology(Electrical India, 2009) Sheth, P.N.Item Differential Evolution Approach for Obtaining Kinetic Parameters in Nonisothermal Pyrolysis of Biomass(Taylor & Francis, 2009-05) Sheth, P.N.Pyrolysis, a first step in the biomass gasification, is the thermal decomposition of organic matter under inert atmospheric conditions, leading to the release of volatiles and formation of char. As pyrolysis is a kinetically controlled reaction, kinetic parameter estimation is very important in the design of pyrolysis reactors. In the proposed kinetic model of this study, the kinetic scheme of biomass decomposition by two competing reactions giving gaseous volatiles and solid charcoal is used. Four different models are proposed based on different possible relation of activity of biomass with normalized conversion. The corresponding kinetic parameters of the above models are estimated by minimizing the square of the error between the reported nonisothermal experimental data of thermogravimetry of hazelnut shell and simulated model predicted values of residual weight fraction using differential evolution (DE), a population-based search algorithm. Among the four different models proposed in this study, the model in which rate of change of activity of biomass with normalized conversion proposed as a function of activity itself gave the best agreement with the experimental data.Item Experimental studies on producer gas generation from wood waste in a downdraft biomass gasifier(Elsiever, 2009-06) Sheth, P.N.A process of conversion of solid carbonaceous fuel into combustible gas by partial combustion is known as gasification. The resulting gas, known as producer gas, is more versatile in its use than the original solid biomass. In the present study, a downdraft biomass gasifier is used to carry out the gasification experiments with the waste generated while making furniture in the carpentry section of the institute’s workshop. Dalbergia sisoo, generally known as sesame wood or rose wood is mainly used in the furniture and wastage of the same is used as a biomass material in the present gasification studies. The effects of air flow rate and moisture content on biomass consumption rate and quality of the producer gas generated are studied by performing experiments. 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. Material balance is carried out to examine the reliability of the results generated. The experimental results are compared with those reported in the literature.Item Thermo-Chemical Conversion of Jatropha Deoiled Cake: Pyrolysis vs. Gasification(IJCEA, 2015-10) Sheth, P.N.Pyrolysis and gasification of biomass is considered to be the promising alternative solutions for the increase of energy demand and environmental awareness. Pyroysis process produces a variety of chemicals by limited degradation and gasification process leads to complete breakdown of the biomass into permanent gases. By gasification, solid biomass is converted into a combustible gas mixture normally called “Producer Gas” consisting primarily of hydrogen and carbon monoxide, with lesser amounts of carbon dioxide, water, methane, higher hydrocarbons, nitrogen and particulates. Whereas the pyrolysis process produces a mainly three types of products: solid (charcoal), liquid (tar and other organics) and gaseous products. In the present study, Jatropha de-oiled cake is taken as a biomass. The pyrolysis and gasification experiments are carried out for comparing the results. The biomass is pyrolyzed in a fixed bed reactor in a Nitrogen environment as well used to produce the producer gas in a fixed bed downdraft biomass gasifier.Item Biomass gasification models for downdraft gasifier: A state-of-the-art review(Elsiever, 2015-10) Sheth, P.N.Among the different methods of energy production from biomass, gasification is considered as the most suitable option as it is a simple and economically viable process to produce thermal energy or decentralized electricity generation. Downdraft gasifiers are typically small-scale units having maximum power production capacity up to 5 MW. This feature makes it more suitable for decentralized power generation and distribution to the remote villages/islands deprived of grid electricity. Mathematical models can be helpful for the design of gasifiers, prediction of operational behavior, emissions during normal conditions, startup, shutdown, change of fuel, change of loading, and to alleviate the type of problems mentioned above. It has been observed that although many researchers have developed models of various types and degrees of complexity, reviews of these modeling and simulation studies are scarce. Largely, it is observed that the review articles reported in the literature fail to address the basic understanding of each model types and their applicability to design different gasifiers for a certain feedstock and variation of operating parameters. This review article discusses different models available for downdraft gasifiers such as thermodynamic equilibrium, kinetic, CFD, ANN and ASPEN Plus models. A comparative analysis of each model and its output is carried out. A critical analysis of the effect of different modeling parameters and finally the advantages and disadvantages of each modeling technique is outlined.Item Design of energy utilization test for a biomass cook stove: Formulation of an optimum air flow recipe(Elsiever, 2019-01-01) Sheth, P.N.Biomass is a major source of fuel in many developing countries and used in cook stoves. The water boiling test or its variants are used to evaluate the performance. The evaluation is on an average basis throughout the test and does not provide the dynamics of the energy transfer process. To provide a better insight on this transfer process, the present study demonstrates energy utilization test, which enables analysis of the performance parameters with respect to time. The WBT experimental set up is modified to measure the variation of biomass fuel consumption and water evaporation separately with time by incorporating the separate top mounted weighing balance. The new variable, weight of the water pot, variation with time is also observed along with other standard WBT variables. This new test is validated by performing several experiments. It provides insights on the time-dependent behavior of thermal efficiency and other parameters when performed at different air flow rates. Based on the test results, a new air flow recipe is developed which provides better performance and outlines the significance of energy utilization test. With the formulated recipe, the runtime has improved to nearly 85 min which is an increase of more than 30%.Item Recent progress in thermochemical techniques to produce hydrogen gas from biomass: A state of the art review(Elsiever, 2019-10-04) Sheth, P.N.The present work comprehensively covers the literature that describes the thermochemical techniques of hydrogen production from biomass. This survey highlights the current approaches, relevant methods, technologies and resources adopted for high yield hydrogen production. Prominent thermochemical methods i.e. pyrolysis, gasification, supercritical water gasification, hydrothermal upgrading followed by steam gasification, bio-oil reforming, and pyrolysis inline reforming have been discussed thoroughly in view of the current research trend and latest emerging technologies. Influences of important factors and parameters on hydrogen yield, such as biomass type, temperature, steam to biomass ratio, retention time, biomass particle size, heating rate, etc. have also been extensively studied. Catalyst is a vital integrant that has received enough attention due to its encouraging influence on hydrogen production. Literature confirms that hydrogen obtained from biomass has high-energy efficiency and potential to reduce greenhouse gases hence, it deserves versatile applications in the coming future. The study also reveals that hydrogen production through steam reforming, pyrolysis, and in-line reforming deliver a considerable amount of hydrogen from biomass with higher process efficiency. It has been identified that higher temperature, suitable steam to biomass ratio and catalyst type favor useful hydrogen yield. Nevertheless, hydrogen is not readily available in the sufficient amount and production cost is still high. Tar generation during thermochemical processing of biomass is also a concern and requires consistent efforts to minimize it.Item CFD analysis of biomass gasification using downdraft gasifier(Elsiever, 2021) Sheth, P.N.CFD model has been developed for the 2D axisymmetric model of an Imbert downdraft gasifier. The present Model has been validated with experimental data. The model predicts CO, hydrogen, and CO2 with precise accuracy. Producer gas composition and gasifier temperature have been studied at different equivalence ratios (ER) i.e. 0.25 to 0.60. It is noted from the observation that the rise of the equivalence ratio tends to decrease the amount of CO, hydrogen, and methane in the producer gas whereas nitrogen and CO2 excessively increased. It has also been observed that the increase of the equivalence ratio tends to increase the temperature inside the gasifier.