The alternative design of bag house with offline cleaning can also be selected. In
this case poppet valves located in the clean air plenum are used to stop the flow
of dirty air into the compartment. Each compartment can be equipped either with
a single pulse valve that supplies compressed air to the group of bags, or have sep
arate pulsing valves that direct pulsing air into the blow pipes above the bag rows
in the compartment. During the cleaning cycle the poppet valve closes, stopping
the air flow through the compartment. The pulse valve opens, supplying a burst of
air into the bags for cleaning. The compartment remains off-line during the clean
ing cycle. The poppet valve then automatically reopens, bringing the compart
ment back on stream. Alternate compartments are cleaned successively until all
the bags in the bag house have been cleaned. This cleaning is called off-line
cleaning.
A typical sketch-2 showing a Pulse jet bag house is shown below.
5.3 Hybrid Filter
The hybrid filter has two compartments, first being an ESP and the second a bag
filter. The initial electrical field is kept to reduce the dust load and wear on for filter
bags (Pre-separation) and charging of dust particles for better agglomeration and
to enhance faster collection on the fabric.
As it requires less space as compared to new PJBH and RABH, for the old plant
with ESP and higher dust emission, the hybrid filter is the adequate solution to
reduce the outlet emission in available space.
5.4 ESP
Up to around 1980, practically all kiln and cooler exhaust dedusting systems
employed electrostatic precipitators. Nowadays, there is a strong downward trend in
most countries because of more stringent emission limit values. Strictly speaking,
these ESP essentially consist of parallel gas channels between metallic collecting