Subject: FGD is a Big Market for Valves
The sudden spurt in construction of new coal-fired plants
and the initiatives to reduce sulfur emissions at existing coal-fired plants in
the U.S. and China are creating a big market for valves. In the McIlvaine report
Industrial Valves: World Markets the revenue forecasts reflect
this opportunity. Hundreds of flue gas desulfurization (FGD) scrubbing systems
will be built. The largest systems will recirculate as much as 400,000 gpm.
A variety of valve types and materials of construction are
in use, and the chief factors that dictate valve selection are corrosion and
erosion resistance, minimum resistance to flow, and positive shutoff in
long-term use.
- Hand-operated valves are of the overhead chain wheel
type or of the gear assistance type. The following valves are typical
hand-operated ones in use in limestone scrubbing systems:
Eccentric plug valves
Lined butterfly valves
Flex check valves
Water knife-gate valves
Water gate valves
- Air-operated or electric-operated control valves are
very important for the control of the various liquor streams in accordance
with the process control scheme. They are also used for the isolation of
equipment, such as pumps. Typical control valves used in a limestone scrubbing
system are pinch valves and plug valves.
- Globe valves are used to control the service water, mist
eliminator wash, and miscellaneous water flows. A few globe-type valves with
favorably formed body passages simulating plug valves have seen service in
slurry control.
- Butterfly valves are used as on-off control valves for
slurry service lines and in recirculation slurry pump discharge piping.
- Knife-gate valves are used for shutoff and also for
modulating service for clear liquor-like streams. The knife-gate valve uses a
shearing action in which its thin disk knifes through any deposit on the valve
seats. The seat rings can be elastomeric, but the disk is usually stainless
steel. A butterfly valve handles less flow than the same size knife-gate valve
because the disk remains in the flowstream with a butterfly valve, while the
gate is entirely outside the flowstream with a knife-gate valve.
- Plug valves are used for isolation service in water
and/or slurry lines. Eccentric plug valves, in which the plug wipes past the
seat and is clear of flow in the open position, have given excellent results
in limestone scrubbing slurry service.
- Quarter-turn valves, in which the stem rotates without
the sliding that permits slurry into the stem packing, are preferred for
slurry service.
Each FGD project is tracked weekly in the McIlvaine service
Utility Environmental Upgrade Tracking System
http://www.mcilvainecompany.com/utilitytracking.htm
The market for valves in all applications in all countries
is forecast in Industrial Valves: World Markets
http://www.mcilvainecompany.com/water.html#n028
Bob McIlvaine
847-784-0012
www.mcilvainecompany.com