Microwave Pyrolysis Characteristics and Solid Product Analysis of PTA Oxidation Residue Based on Combined Multi-mode Cavity

In order to study the characteristics of microwave pyrolysis in multi-mode resonant cavity and guide the industrial application of microwave pyrolysis technology, pyrolysis of purified terephthalic acid (PTA) oxidation residue at various temperatures were carried out by using the self-developed combined multi-mode cavity microwave pyrolysis device and ordinary tubular atmosphere furnace. The effects of the number and distribution of microwave feeders on the pyrolysis heating characteristics, solid product yield, solid product characteristics and device energy consumption were analyzed. The results show that compared with the conventional tubular furnace pyrolysis at the same pyrolysis temperature, the yield of microwave pyrolysis solid products under different feed forms is significantly reduced, the solid products of microwave pyrolysis O/C and H/C are lower, the high calorific value is higher, and the energy consumption is lower. When the four feed ports EH–HE type distribution is adopted, the heating rate of microwave pyrolysis is the fastest, the solid product yield, O/C and H/C under 600 ℃ pyrolysis are the lowest, and the high calorific value is 23.19 MJ/kg, but the energy consumption is only 54.48% of that of the tube furnace. The above results imply that microwave pyrolysis treatment of PTA oxidation residue has advantages in heating efficiency, solid product yield, calorific value and unit energy consumption, and the four feeder EH–HE distribution scheme is more suitable for high-temperature pyrolysis.