COMBUSTION AND GASIFICATION PROPERTIES OF PLASTICS PARTICLES

The combustion and gasification behavior of the most common plastics i s studied and compared with conventional fuels such as coal, peat, and wood. The aim is to give background data for finding the optimum cond itions for co-combustion or co-gasification of a conventional fuel wit h a certain amount of plastic-derived fuel. Atmospheric or pressurized fluidized bed co-combustion of conventional fuels and plastics are co nsidered to be promising future options. The plastics investigated wer e poly(ethylene) (PE), poly(propylene) (PP), poly(styrene) (PS), and p oly(vinyl chloride) (PVC). Some of the samples had a print or color. T he reference fuels were Polish bituminous coal, Finnish peat, and Finn ish pine wood. PE, PP, and PS were found to burn like oil. The particl es shrank to a droplet and burned completely during the pyrolysis stag e, leaving no char. Printing and coloring left a small portion of ash. PVC was the only plastic that produced a carbonaceous residue, and it s timescales for heating, devolatilization, and char burning were of t he same order as those for peat and wood, and much shorter for the oth er plastics studied. An important result is that char from PVC contain s less than 1% chlorine, 99% hydrocarbon. The gasification rate of PVC char (at 1 bar and 25 bar) was of the same order as that of char from coal. Feat-char and wood-char were gasified an order of magnitude fas ter.