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Since the Max-9 is essentially a high-efficiency pulse-jet baghouse, it’s
inherent collection efficiency is extremely good. However, it is useful to think of the Max-9 as
an electrostatic precipitator without collecting plates. When the dust particles are charged, they
are attracted to the grounded metal cage inside the filter element, just as they would be attracted
to the collecting plates in an ordinary precipitator. Since the particles are charged positively,
they repel each other on the surface of the filter, making the collected dustcake very porous. This
results in a reduction of the K2 factor, which is an indication of filter drag. In the SRI test
facility, K2 dropped from a value of 14.5 to about 4. This makes the conventional filter bags far
more effective. The reduced K2 means that the Max-9 filter operates at a pressure drop about 25%
of a normal fabric filter. Consequently, the Max-9 can operate at an air-to-cloth ratio higher than
a conventional fabric filter. Max-9 modules can treat a significant gas volume with a small footprint.
The Max-9 can be supplied as shop-assembled modules that can be erected on site, although the
units are usually custom-engineered for each plant site and application to make the best use of
available space.
Max-9 System – Design Overview
Process gas enters the Max-9 from a hopper inlet duct. The gas then flows upward through the
filters and out through the top of the filters. The area above the tube sheet is a clean gas plenum.
Compressed air pulses are used to clean the filters. A brief, intense blast of air is fired through
the purge air manifold; holes in the blowpipes located above the filters direct the cleaning air
pulse down through the filters. The cleaning sequence is controlled by timers which trigger solenoids.
The high voltage system (depicted in blue) operates at very low current densities and at a steady
state. There is no danger of fire caused by sparking, and the transformer/rectifier requires no
voltage control.
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