2. Experimental Section
2.1. Experimental Apparatus. A process flowchart of the
VFBC combustion system used in this study is shown in Figure 1.
The fluidizing air as well as the primary combustion air is supplied
by a 15 hp Root’s blower. The second air is supplied by a 7.5 hp
turbo blower. Four equally spaced second air injection nozzles with
diameters of 12 mm are installed tangentially at a level of 1.3 m
above the distributor to cause the swirling flow in the freeboard. A
20 hp compressor is used for transporting the feed through a pipe
into the combustor.
Figure 2 shows the configuration of the VFBC used in this study.
The VFBC is made up of four parts, i.e., the windbox, the
distributor, the combustion chamber, and the freeboard. The
combustion chamber with cross section 0.64 × 0.32 m2 is
constructed of a 6 mmstainless steel covered with the ceramic fiber
to limit the heat loss. A windbox with cross section 0.64 × 0.32
m2, connected to the air supplied line, is fabricated of 6 mm stainless
steel. Above the combustion chamber, the inner diameter of the
freeboard is 0.45 m. The static bed height is 0.3 m. Thirty-one
horizontal nozzles with diameters of 6.8 mm mounted on a 6 mm
thickness stainless steel plate are used as the gas distributor (the