A simple apparatus was constructed for a Canadian University. The original intent was to lightly depolymerize plastic for use as an additive in the manufacture of a specialty product. Samples were prepared using the apparatus and sent to the University for testing. While waiting for the test results and confirmation that the apparatus was preparing a satisfactory feestock, a series of tests on wood, sewage sludge, and reed canary grass was conducted.
The results were very encouraging and provided insight into the control over the yield split between char, liquid and gas. The apparatus was not designed for accurate mass balance determinations and only the char yield could be determined with some certainty. The following graph shows some preliminary results. Assuming that the softwood contains 3% ash, 12% fixed carbon, and 85% volatile matter, then the theoretical minimum amount of char produced is 15% (ash plus fixed carbon). Stated in another way, the amount of char measured is a function of the percentage of volatile matter driven off during the heating process.