P06 – Parag R. Gogate

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Process intensification of chemical processing applications using cavitational reactors: design, scale up and applications

Chemical Engineering Department, Institute of Chemical Technology, Mumbai – 400 019, India

* email: pr.gogate@ictmumbai.edu.in

Abstract:

Cavitational reactors are a novel and promising form of multiphase reactors, based on the principle of release of large magnitude of energy due to the violent collapse of the cavities. Use of cavitational reactors for process intensification of several chemical and physical processing applications has been exploited worldwide in recent years. The present talk aims at presenting an overview of design and operation of cavitational reactors also focusing on the different areas of applications in the area of chemical processing illustrating some typical case studies.

The initial part of the talk will be devoted to basic concepts of cavitation phenomena and mechanism of observed intensification in different chemical systems. It will be demonstrated that depending on the application in question, it is most important to identify the controlling mechanism and then adjust the design and operating parameters[1] so as to maximize the intensification benefits. Bubble dynamics analysis for the prediction of the cavitational intensity in the reactor and its use for establishing the best conditions for the optimum design and operating parameters will also be presented. Different designs of cavitational reactors including sonochemical and hydrodynamic cavitation reactors will be discussed and comparison will be presented using two criteria of energy efficiency and cavitational yield estimations for different applications based on the work done by the research group. Some discussion on the commercial applications harnessed successfully will also be presented highlighting the obtained benefits and recommendations for large scale reactors. A successful commercial installation applied for treatment and recycle of frac water in oil and gas explorations will be discussed. The reactor is based on the combined usage of hydrodynamic cavitation, ultrasound and ozone giving synergistic results and has been successfully used for processing of the recycled fluids at commercial sites on over 1200 oil and natural gas wells during hydraulic operations[2].

The talk will also present some experimental case studies using industrially important operations such as chemical synthesis and wastewater treatment highlighting the degree of intensification achieved as compared to the conventional approaches. One specific study related to industrial wastewater treatment[3] based on real effluent from specialty chemical manufacturing unit will be discussed in details. In the work, the effluent treatment was based on the application of hydrodynamic cavitation alone and in combined operation with other oxidation processes focusing on the main objective of a COD reduction. The pretreatment of HC+Fenton process followed by conventional biological oxidation resulted in COD reduction of about 98% (final COD ≤ 250 mg/L), which meets the discharge water compliance. Overall it appears that considerable economic savings is possible by means of harnessing the spectacular effects of cavitation in chemical physical processing.

Keywords

Reactor Designs; Operating parameters; Chemical processing; Process intensification; Scale up

References

[1]           P.R. Gogate, V.S. Sutkar, A.B. Pandit, Chemical Engineering Journal, 166 (2011) 1066-1082

[2]           P. R. Gogate, D. McGuire, S. Mededovic Thagard, R. Cathey, J. Blackmon, G. Chapas, Ultrasonics Sonochemistry, 21 (2014) 590-98

[3]           P.D. Thanekar, P.R. Gogate, Separation & Purification Technology, 239 (2020) Article 116563

Acknowledgements

Authors would like to acknowledge the funding of Department of Science and Technology, India and University Grants Commission India for some of the research work demonstrated in this talk.

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