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Monitoring of Biodiesel Transesterification Process Using Impedance Measurement

Rachmanto, T (2014) Monitoring of Biodiesel Transesterification Process Using Impedance Measurement. Doctoral thesis, Liverpool John Moores University.

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Abstract

Alternative diesel fuels have been the subject of extensive investigation. Fatty acid methyl ester (FAME) based Biodiesel manufactured from vegetable oils or animal fats is an excellent candidate to replace common diesel fuel being renewable, non-toxic and often giving rise to reduced exhaust gas emissions. The transesterification process has been commonly and widely used to produce biodiesel from vegetable oil or animal fat. Vegetable oils or animal fats generally have viscosities higher than standard diesel oil. This means that it is necessary to reduce the viscosity by means of reacting vegetable oil with alcohol in the presence of a suitable catalyst. The target product for this reaction is methyl ester, with glycerol and potentially soap produced as by products with the process of transesterification. Methylester (Biodiesel) is produced by converting triglycerides to alkylesters. A batch transesterification process has two significant mechanisms, and exhibits a mass transfer controlled region that precedes a second order kinetically controlled region. In order to control the conversion process it is useful to employ process monitoring. In particular monitoring of the mass transfer processes that limits the initial reaction rates could prove to be beneficial in allowing for process optimization and control.

This thesis proposes the use of a new method of biodiesel process monitoring using low frequency (15kHz) impedance sensing which is able to provide information regarding the progress of mass transfer and chemical reaction during biodiesel production. An interdigitated (ID) sensor has been used to monitoring the biodiesel process The ID sensor is of simple construction and consists of two sets of interleaved electrodes (fingers). The two sets of electrodes are separated by a gap and when an AC excitation voltage is applied across the interleaved electrodes an oscillating electric field is developed. The response of the fluid surrounding the sensor to the applied excitation was then used to determine progress of the chemical reaction by evaluating the real and complex impedance. A significant and unambiguous change in the components of impedance has been shown to occur during mixing (mass transfer) and transesterification.

The impedance measurements gained during transesterification were then used for the development of a system model. A systematic approach was used to select mathematical models and system identification techniques were evaluated. The system identification investigation used real process measurement data in conjunction with the Matlab system identification toolbox.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Biodiesel monitoring process, Impedance Measurement, Interdigital Sensor, Capacitance sensor, System Identification
Subjects: T Technology > TC Hydraulic engineering. Ocean engineering
T Technology > TD Environmental technology. Sanitary engineering
Divisions: Maritime and Mechanical Engineering
Date Deposited: 04 Nov 2016 12:52
Last Modified: 04 Nov 2016 12:52
Supervisors: Allanson, David and Matthews, Christian
URI: http://researchonline.ljmu.ac.uk/id/eprint/4337

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