Product Yields and Compositions in the Continuous Pyrolysis of High-Density Polyethylene in a Conical Spouted Bed Reactor

The pyrolysis of high-density polyethylene (HDPE) has been carried out in the range between 500 and 700 degrees C in continuous mode in a pilot-plant unit equipped with a conical spouted bed reactor. The products have been grouped into the lumps of gas (C4-), gasoline (C-5-C-11), diesel (C-12-C-20), and waxes (C21+). The product yields and compositions of these fractions were compared both to those previously obtained in the pyrolysis performed in discontinuous mode and to those obtained by other authors in fluidized bed reactors. The results confirm the optimal performance of the conical spouted bed reactor (CSBR) in obtaining high yields of waxes and fuels with low aromatic content, which is explained by the appropriate conditions of the CSBR needed to enhance heat and mass transfer between phases (capacity for coating the sand with plastic) and minimize secondary reactions (short residence time of the volatiles).