5.15.1 Summary

Union Fenosa undertook the construction of a substantial pilot plant in 1989 for the production of pyrolysis liquids for fuels. After a thorough review of available technologies at that time, a license was agreed for the Waterloo Flash Pyrolysis Process (WFPP) developed by the University of Waterloo in Canada (q. v.).

Construction started in 1990 and commissioning started around October 1992. By mid 1993 the unit was operating reasonably satisfactorily at 160 kg/h dry wood throughput, although some problems with liquid collection had to be resolved. Work is continuing on developing the process and considering scale-up.

5.15.2 Description

The flowsheet is shown in Figure 5.13 (6, 69). After storage the eucalyptus feed is ground then dried with propane. A cyclone removes fines prior to venting the combustion products to atmosphere. The dried feed is stored in a closed hopper prior to metering to the fluid bed pyrolyser. The fluidising gas is recycle gas supplemented with nitrogen as required. The gas is heated with a propane fired heat exchanger.

The product char is separated in a cyclone and stored in a closed container. The vapours are cooled in two water cooled heat exchangers in series, then passed through a demister and a final cooler to remove as much oil as possible. All liquid product streams are combined.

5.15.3 Products

Detailed mass and energy balances and product analyses are not available at this time, but reported char yields of around 20% wt on dry feed (60) are closer to 15% (71). Oil yields in excess of 55% wt. have been indicated (60) although it seems likely that the oil yield is nearer 65-70% wt. . At the end of the first phase of the work in summer 1993, Fenosa admitted that it had not been possible to produce pyrolysis oil of the right quality. The early operational difficulties in producing a consistent quality oil have now been mostly solved and the plant is producing a consistent relatively viscous liquid with a water content of 15 wt%.