Three-dimensional simulation of a novel microwave-assisted heating device for methyl ricinoleate pyrolysis

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.