16-11-2012, 04:57 PM
FLUIDIZED BED
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ENRICHMENT ACTIVITIES [Areas of Research]
Pressurized Fluidized Bed Combustors (PFBC) are only one of several
advanced approaches for substantially improving the efficiency of coal-fired power
systems, while significantly reducing environmental emissions. The PFBC system uses
sorbent such as limestone or dolomite to capture sulfur released by the combustion of
coal. Jets of air suspend the mixture of sorbent and burning coal during combustion,
converting the mixture into a suspension of red-hot particles that flow like a fluid.
Elevated pressures and temperatures produce a high-pressure gas stream that can drive
a gas turbine, and steam generated from the heat in the fluidized bed is sent to a steam
turbine, creating a highly efficient combined cycle system.
Biological Filter System - The most efficient and dependable biological filter is
the fluidized bed filter. The principles of this filter are very attractive to commercial
applications because of the dramatic increase in surface area and reduced real estate
requirement. Providing that the design of the fluidized bed is sound, this style of
biological filter is by far the most efficient. Competing styles such as the rotating
barrel contractors and packed-column towers (wet dry filters) are not as attractive as
the fluid bed filter. It tends to accumulate particle waste or contains too many moving
parts. The fluidized bed filter with its tremendous surface area is about as close to
automatic as is developed.
Project Instructions:
1. Cut off two 2-liter bottles eight cm. (three inches)
from the top and eight cm. from the bottom. You
will have a straight section of plastic bottle with a
uniform shape. Fit the two pieces together.
2. Cut a round hole into the top of the box so that one
of the straight sections made in STEP 1 will fit
snugly into the hole. (Keep the piece of cardboard
cut out.)
3. Cut three square pieces of window screen about
three cm on each side larger than the hole made in
STEP 2. Stack these three pieces on top of each
other and tape the sides together. Make sure the
tape does not cover more than 1 cm of the screen’s
edge. Cover on the inside the hole made in STEP 2
with the screens and tape them into place. Fit the center piece from the
2 liter bottle into the hole and tape it securely in place so that air can not
leak around the piece.
ACTIVITIES
Have students feel the texture of the rice as the air flows through, then turn the air off.
Notice the change in texture. You may wish to substitute a three liter bottle so
students will have more area to insert their hand to feel the rice.
Turn off the dryer and place a cotton ball and one of the lids from the 2-liter soda
bottles on the “puffed rice” bed. Turn on the dryer and notice what happens to the
cotton ball and the lid.