Browsing by Author "Sheth, P.N."

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Advances in Downdraft Biomass Gasification
(‎ Nova Science Publishers, 2010) Sheth, P.N.
Biomass gasification coupled with producer gas cleaning, bottling and HTS catalyst treatment for H2-rich gas production
(Elsiever, 2019-05-03) Sheth, P.N.
The aim of the present study is to demonstrate the production of hydrogen-rich fuel gas from J. curcas residue cake. A comprehensive experimental study for the production of hydrogen rich fuel gas from J. curcas residue cake via downdraft gasification followed by high temperature water gas shift catalytic treatment has been carried out. The gasification experiments are performed at different equivalence ratios and performance of the process is reported in terms of producer gas composition & its calorific value, gas production rate and cold gas efficiency. The producer gas is cleaned of tar and particulate matters by passing it through venturi scrubber followed by sand bed filter. The clean producer gas is then compressed at 0.6 MPa and bottled into a gas cylinder. The bottled producer gas and a simulated mixture of producer gas are then subjected to high temperature shift (HTS) catalytic treatment for hydrogen enriched gas production. The effect of three different operating parameters GHSV, steam to CO ratio and reactor temperature on the product gas composition and CO conversion is reported. From the experimental study it is found that, the presence of oxygen in the bottled producer gas has affected the catalyst activity. Moreover, higher concentration of oxygen concentration in the bottled producer gas leads to the instantaneous deactivation of the HTS catalyst.
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.
Biomass thermo-chemical treatment methods and techno-economic assessment
(Springer, 2018) Sheth, P.N.
The concerns relating to global warming, climate change, and increasing energy demands have led to significant research towards the development of alternative energy to substitute the fossil energy sources. Biomass-based energy or biofuels are highly promising due to many perceptible environmental and socio-economic advantages. Cutting-edge academic research and advanced industrial product development have created tremendous scope for the implementation of biofuels at a global scale to reduce the greenhouse gas emissions and supplement the escalating energy demands. The prime focus of this book is to provide an overview of the different technologies utilized to harness the chemical energy from plant-based non-edible biomass and other organic wastes in the form of solid, liquid, and gaseous biofuels. The opportunities and challenges of different biomass conversion technologies, especially biomass-to-liquid, biomass-to-gas and gas-to-liquid routes, as well as biomass pretreatments, densification, anaerobic digestion, reforming, transesterification, supercritical fluid extraction, microalgal carbon sequestration, life-cycle assessment and techno-economic analysis have been comprehensively discussed in this book. This book is an amalgamation of fifteen different chapters each with distinctive investigations and a collective focus relating to the transition from fossil fuels towards carbon-neutral biofuels. This book serves as a benchmark for academic and industrial researchers involved in exploring the true potentials of plant residues and waste organic matter to produce alternative renewable fuels. To realize the real promises of bioenergy, this book attempts to assess the biorefining approaches, biofuel production and application, and environmental sustainability.
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.
Content Contributions to the Indian Adaption of Transport Phenomena
(Wiley, 2021) Kuncharam, Bhanu Vardhan Reddy; Sheth, P.N.
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%.
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.
Energy Integration in Process Plants
(CRC, 2017-03) Gupta, Suresh; Sheth, P.N.
Increased research is going on to explore the new cleaner options for the utilization of natural resources. This book aims to provide the scientific knowhow and orientation in the area of the emerging technologies for utilization of natural resources for sustainable development to the readers. The book includes production of energy and lifesaving drugs using natural resources as well as reduction of wastage of resources like water and energy for sustainable development in both technological as well as modeling aspects.
Energy Integration in Process Plants
(CRC, 2017) Sheth, P.N.
Increased research is going on to explore the new cleaner options for the utilization of natural resources. This book aims to provide the scientific knowhow and orientation in the area of the emerging technologies for utilization of natural resources for sustainable development to the readers. The book includes production of energy and lifesaving drugs using natural resources as well as reduction of wastage of resources like water and energy for sustainable development in both technological as well as modeling aspects.
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.
Modeling and Simulation of Reduction Zone of Downdraft Biomass Gasifier: Effect of Air to Fuel Ratio
(JET, 2007) Sheth, P.N.
Biomass mainly in the form of wood is the oldest form of energy used by humans. Biomass generally means a relatively dry solid of natural matter that has been specifically grown or has originated as waste or residue from handling such materials. The thermochemical conversion of biomass (pyrolysis, gasification, combustion) is one of the most promising non-nuclear forms of future energy. In the present study, the model reported in literature is simulated to study the effects of pyrolysis fraction on the outlet gas concentration in a downdraft biomass gasifier. It is found that the air to fuel ratio is one of the key parameters in the reduction zone of downdraft biomass gasifier. It effects the value of pyrolysis fraction in the model, and indirectly proportional to the pyrolysis fraction. Steady state composition and temperature profiles for the reduction zone of the downdraft biomass gasifier are also predicted for various values of air to fuel ratio.
Multi reaction apparent kinetic scheme for the pyrolysis of large size biomass particles using macro-TGA
(Elsiever, 2018-05-15) Sheth, P.N.
In the present study, the pyrolysis of biomass is proposed by one step multi reaction apparent model. It is expressed as parallel production of bio-oil, gases and charcoal. Macro TGA of Jatropha de-oiled cake is performed at temperatures ranging from 350 °C to 700 °C. The volatiles released during pyrolysis exits from the top of the reactor and are cooled in a two-stage condenser followed by an ice trap. The weight reduction variation of the biomass with time, product yield and composition of non condensable gases are measured and used to develop the apparent kinetic model. The corresponding apparent kinetic parameters are estimated by minimizing the square of the error between simulated values of residual weight fraction and experimental values using non-traditional optimization technique logarithmic differential evolution (LDE). The weight reduction with time suggests that the pyrolysis of de-oiled cake is carried out in three stages. The maximum liquid yield obtained is 31.2% at 500 °C, which further decreases with an increase in temperature. The model predicted values of residual weight fractions and yield of products are matching very well with the experimental data for all reactor temperature.
Power Generation from Biomass Gasification: A Renewable Energy Source based Technology
(Electrical India, 2009) Sheth, P.N.
Process simulation of hydrogen rich gas production from producer gas using HTS catalysis
(Elsiever, 2019-04-15) Sheth, P.N.
In the present article, ASPEN Plus is used to develop a process model of the hydrogen-rich gas production through cleaning and catalytic conditioning of producer gas. The process includes producer gas cleaning using venturi scrubber and sand bed filter followed by compression of the gas to 0.6 MPa using compressor. The clean producer gas along with steam undergoes high temperature water gas shift reaction to produce hydrogen-rich gas. The power law kinetic model for commercial HTS catalysts reported in the literature is used in the model. Experimental results from our previous study and those reported in the literature are used to validate the developed model for the compositions of CO & H2 in the product gas. The validated model is further simulated to study the effects of parameters such as reactor temperature, catalyst bed length and steam to CO ratio on the product gas composition. The optimum operating conditions for maximizing CO conversion are found and reported. The maximum H2 composition and CO conversion predicted by the model are 27.029% 97.5479% respectively and the corresponding operating conditions are reactor; temperature of 350 °C, S/CO of 8 and GHSV 1000 h−1.
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.
Study of the Production Technologies of Heavy Crude Oil
(IUP, 2010-11-10) Sheth, P.N.
Roughly 10% of the world’s daily supply of petroleum is so thick that it cannot flow through pipelines on its own. The importance of heavy oil often defined as anything less than 20 American Petroleum Institute (API) gravity is escalating due to its sheer volume. While proven oil reserves worldwide stand at more than 1,200 billion barrels of conventional crude oil, the amount of heavy oil in place is five to ten times greater. In the decades ahead, heavy oil is likely to affect the global supply dynamics since 80% of the known heavy oil reserves are in the western hemisphere. It is mandatory that India utilizes the most of what it has. The problem is that heavy crude oil is notoriously difficult to recover, transport and refine. Only 6-8% of the available oil is considered recoverable with conventional technology. The main technical challenges are to lower the viscosity of the oil, understand its composition and handle heavier components. In the present study, various technologies related to the production of heavy crude oil are reviewed. The largest and the newest heavy oil field in India, i.e., Barmer region, Rajasthan, is considered as a case study.
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.
Waste-to-Energy: Issues, Challenges, and Opportunities for RDF Utilization in Indian Cement Industry
(Springer, 2021) Sheth, P.N.