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Microwave-assisted fast pyrolysis of hazardous waste engine oil into green fuels 135

Fig. 5.6 Specific energy consumption for different pyrolysis mechanisms.

of susceptors has been beneficial in reducing the specific energy consumption by
nearly four times compared to microwave pyrolysis without susceptors.

5.11 Comparison of electrical and microwave pyrolysis
process yield at different conditions

5.11.1 Pyrolysis liquid yield

In electrical heating pyrolysis, pyrolysis oil yields increased with an increase in tem-
perature. Due to the increase in temperature, the kinetic energy of gas increased and
decreased the retention time, resulting in a significant amount of liquid fraction
obtained at a temperature of 350°C. An increase in nitrogen flow rate also enhanced
the increase in the amount of liquid fraction from 2 to 3L/min. A further increase in
nitrogen flow rate along with temperature did not make any difference in improving
the liquid fraction obtained. An increase in stirrer speed, a further increase in kinetic
energy needed for pyrolysis, and hence more yield of the liquid fraction was obtained.
Complete evaporation happened beyond the temperature of 350°C, and a broad opti-
mum region of oil yield was obtained at 20rpm of stirrer speed, as shown in Fig. 5.7.
In MAP, due to high localized heat generation over conventional heating, the pyrol-
ysis oil yield increased with an increase in temperature but the optimum temperature
at which the maximum fraction obtained was 350°C. Moreover, an increase in
the nitrogen flow also improved the yield of pyrolysis oil, but beyond the N 2 flow rate