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*Corresponding author: [email protected]
2
Advancements of Cavitation Technology in Biodiesel Production – from Fundamental Concept to Commercial Scale-Up
Ritesh S. Malani1, Vijayanand S. Moholkar2, Nimir O. Elbashir3 and Hanif A. Choudhury3*
1Department of Petrochemical and Energy Engineering, Institute of Chemical Technology, Mumbai – IndianOil Odisha Campus, Bhubaneswar, Odisha, India
2Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
3Chemical Engineering Program, Texas A&M University at Qatar, Education City, Doha Qatar
Abstract
Renewable energy and fuels have gained significant attention over the last two decades, with a remarkable increase in their production. Among the renewable fuels, biodiesel has emerged as a promising alternative to mineral diesel due to its performance characteristics in the diesel engine. To meet future demands, the production of biodiesel must be efficient in terms of energy, cost, and processing time. As the process involves the two immiscible phases, adequate mixing is necessary to produce appropriate intermixing between the reactants. The application of the heterogeneous catalyst further augments the mass transfer barrier in the reaction system. The conventional methods are insufficient to increase biodiesel production at the demanded rate. The application of ultrasound for the transesterification process opens new opportunities for researchers and engineers to fulfil the future renewable energy demand. The cavitation process in the reaction mixture will help reduce the surface tension between the reactants, improves their intermixing to form a fine emulsion. The present book chapter will emphasize the fundamental aspects of the cavitation phenomenon and its role in process intensification. The advancement in designing and developing the cavitational process for large scale biodiesel production has been explored and analyzed in terms of fundamental concepts.
Keyword: Biodiesel, transesterification, ultrasound, hydrodynamic cavitation, reactor design, process scale-up
2.1 Introduction
Demand for energy, mostly in terms of transportation fuel and electricity, has increased remarkably over the last few decades and will continue to grow in the future with the rising population [1, 2]. The major energy demand is fulfilled by fossil fuels such as coal, crude oil, and natural gas. Because of the limited reservoirs of conventional fossil fuels, their dwindling prices and environmental concerns, the research community has been compelled to look for alternative energy sources for sustainable development of human society. Researchers have explored several alternatives to fossil-based energy sources to fulfil the demand for electricity and transportation fuel. Among these, biodiesel has become a promising alternative to conventional diesel; it can be used in the existing diesel engine with minor alterations [3]. Using biodiesel in a diesel engine either in blended or in the pure form will reduce the detrimental effect of toxic gases on the environment [4]. Use of biodiesel can also support the sustainable development in rural areas by creating agricultural employments and a sustainable energy security for countries that are highly dependent on crude oil imports [5]. Biodiesel, being a renewable fuel, has several advantages over conventional diesel, such as higher lubricity, superior cetane number with improved combustion efficiency, reduced emission of aromatics, higher flash point, etc. [6, 7]. Technically, biodiesel is a mixture of mono-alkyl methyl esters obtained from the reaction of short-chain alcohols and triglycerides or free fatty acids [8]. Conventionally, biodiesel is prepared from vegetable oils (mostly edible only); however, the increase in demand for energy due to population growth and debate on food security over fuel supply has led to a search
