module is in the normal operating mode. The isolation
valves are open and the gas is being filtered by the
module has been isolated from flue gas flow by closing
the outlet valve, and the bags are being pulsed to remove
the filter cake. The cleaning is done off-line to allow
ash to fall to the hopper, instead of being re-intrained
and deposited back on the bags. On-line cleaning is
is a single point duct connection and the manifold evenly
distributes the gas and particulate to the individual
inlet valve is used to isolate the baghouse during off-line
periods and when the by-pass is open. It stays open
during off-line bag cleaning.
diffuser prevents direct particulate impingement on
the bags and evenly distributes the gas and particulate
to all bags.
bag is the collection device. Fabric selection is one
of the most important design decisions. Primary factors
influencing fabric choice are the flue gas temperature
and chemical composition, efficiency requirements, and
cost and reliability considerations.
bag is supported by a rigid wire single piece cage.
Construction is typically 20 vertical wires with rings
on 6" centers. The cage and integral venturi can
be made of carbon steel, galvanized carbon steel or
various stainless steels, depending on the flue gas
tubesheet supports the bags and cages and forms the
interface between the clean and dirty gas plenums of
the baghouse. The tolerance of the bag holes is critical,
along with the structural design and welding quality.
double diaphragm pulse valve delivers a split second
burst of compressed air to form a shock wave that travels
the length of the bag, "snapping" it and casting
the ash off.
blowpipe delivers the compressed air pulse to the throat
of a venturi located at the top of each bag. BET's exclusive
manufacturing QC assures correct blowpipe hole placement
and alignment to avoid premature bag failure.
supply pipe to the pulse valves is large enough so that
it does not throttle the pulse, and also serves as a
compressed air reservoir.
gas flow from the individual modules is manifolded to
a single point duct connection.
clean side of the baghouse can be isolated by a reliable
poppet type valve. This isolation is done for off-line
bag cleaning as well as shut-down and by-pass conditions.
cross over duct between the inlet and outlet manifold
contains a 100% sealing valve. When this valve is opened
and the module inlet and outlet valves are closed, the
baghouse is by-passed. This is important to protect
the equipment during process upsets, and also is frequently
used as part of the start-up and shut-down sequence.
BET baghouses use top bag access to provide a safe,
relatively clean work environment for bag maintenance.
We offer three basic alternative arrangements of this
top bag access: Individual Doors, Walk-in Clean Air
Plenum, and Lift-off Module Tops (Beta Style Doors).
The advantages and disadvantages of each are identified
in the tables below.