Flashpyrolysis of peat, wood, bark and lignin. Part 2. Pyrolysis tests with Finnish peat at the University of Waterloo

Flash pyrolysis is the rapid thermal decomposition of an organic material in an oxygen-free atmosphere. Research on Marsh pyrolysis is a rather new acid, whilst research on conventional pyrolysis, employing slow heating, has long traditions. By using flash pyrolysis, it is possible to convert a large part of the feed material into organic liquids. This liquid material can be used directly as a fuel oil. After further treatment it could possibly be used as a source of motor fuels or chemicals. The publication deals with flash pyrolysis tests carried out with Finnish Peat in fluidized bed reactors. The experimental work was performed at the University of Waterloo, Canada. A bench-scale unit (10 - 100 g/h) was the main tool in this test programme. In one experiment a larger (pilot) unit (1 - 3 kg/h) was employed. Earlier pyrolysis tests with wood, bagasse, peat, straw and coal provided interesting reference data. The main objective of the work was to investigate the effects of temperature (range 450 - 750 °C), reactive atmosphere (nitrogen, methane), and gas-phase residence time (0.30 - 1.00 s) on the organic liquid yields. The pilot run was done at near optimal conditions to produce a larger quantity of organic liquid. The highest yield of recovered organic liquids, about 50 wt-% of moisture and ash-free raw material, was found at about 450 - 475 °C using the shortest residence time, 0.30 s. At temperatures over 500 °C, the organic liquid yield decreased quickly in favour of gaseous component such as carbon monoxide and hydrocarbons. The maximum yield of light olefins was found to be about 10 wt-% at the highest temperature employed (750 °C). Methane was an inert reaction gas in the conditions of these tests. The toal recovery of pyrolysis produces was excellent, typically 98 - 100 %. The pyrolysis tests were carried out under virtually steady-state reaction conditions. Agreement between the bench-scale result and the pilot test results was very good