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A stable high-temperature reaction site and the rapid and uniform heating of the feedstocks are particularly important in pyrolysis. A novel device consisting of microwave-assisted heating (MAH) coupled with atomization feeding was used for continuous pyrolysis of methyl ricinoleate (MR) using silicon carbide (SiC) as the microwave absorbent bed. The heat transfer in microwave heating and MR pyrolysis in MAH device was studied by three-dimensional simulation. The effects of number of ports and heating power in microwave heating process, flow rate, feed mode and average droplet diameter of MR in pyrolysis process were investigated. Uniform temperature distribution of SiC bed surface was obtained with different numbers of ports. Higher energy efficiency was obtained at higher microwave power, with the highest value reaching 81% at 1000 W. The maximum flow rate of MR could reach 40 mL/min at a stable high-temperature bed surface. The atomization feed mode was beneficial to the temperature uniformity of SiC bed. The heating rate of atomized MR droplets was about 50000 °C/s, significantly higher than that of dropped MR droplets. The simulated results agreed well with the experimental results. It indicated the MAH coupled with atomization feeding could provide a stable high-temperature reaction site and increase the rapid and uniform heating of the feedstocks.

Undecylenic acid methyl ester (UAME) and heptanal (HEP) are important chemical intermediates, which can be produced from pyrolysis of methyl ricinoleate (MR). The temperature gradient existing in conventional tubular reactor for MR pyrolysis would cause the reduction of UAME and HEP yields. An inductively heated reactor coupled with atomization feeding was developed in this study and used for MR pyrolysis. Numerical simulation was first adopted to examine the effect of nozzle number on temperature distribution of the reactor. Results showed that uniform temperature distribution was achieved when three nozzles were used. The average temperature and the standard deviation of the reaction area were 496.54 °C and 6.34 °C respectively at the set temperature of 500 °C. Experimental tests of MR pyrolysis on the reactor were then performed using three nozzles. Results showed that MR conversion increased with the increasing temperature from 440 to 560 °C. The highest UAME and HEP yields of 56.1 wt% and 60.2 wt% respectively were achieved at 520 °C. The product yields were obviously higher than those obtained using conventional tubular reactor. It was mainly due to the uniform temperature distribution of reactor and rapid heating of feedstock by using the inductively heated reactor coupled with atomization feeding.