Valves For Power Plant Air And Water Systems Is The “Hot Topic” For January 24
At 9:00 a.m. CST
It has been nearly a year since we had our “Hot Topic” discussion on Valves. The interest was high enough and the questions challenging enough that the session lasted over two hours. Some of the highlights are covered below:
On Thursday, January 17, the “Hot Topic” is NOx Reagents. To learn more or register for upcoming “Hot Topic” webinars, click on: http://www.mcilvainecompany.com/brochures/FGDnetoppbroch/Default1.htm .
Valve Design and Materials are questions addressed in “Hot Topic Hour” March 22, 2007
The valve “Hot Topic” discussion was definitely global with Patrick Heller participating from Australia and Werner Kremer commenting from Germany. The five presentations were crammed with good information and substantial differences in point of view.
Particulate Decision Tree
Tyco-Goyen – Patrick Heller
Patrick Heller talked about the special use diaphragm valves to clean fabric filter dust collectors. Pulse air is used for cleaning. The blowtube is an extension of the valve. Pipe design should have balanced pressure. More plants are running at lower header pressure and they are cleaning more cloth area per valve. Both trends point to use of larger valves to deliver necessary pressure. There are many design considerations which will result in lower power consumption for a given quality of cleaning. Bag life extension is another important parameter.
FGD Decision Tree
ITT Engineered Valves – Dan Ellis
Dan Ellis discussed the various possible valves that could be included in FGD units. He felt that the rule of thumb would be that any slurry greater than five percent should use a knife gate valve because of its positive shut off and long term use. Below five percent a ball, plug, butterfly or diaphragm could be used. A cost saving possibility would be to use pinch or diaphragm for smaller valves instead of using a knife gate. Control valves would be best using diaphragm or ceramic ball valves.
Larox – Todd Loudin
Todd Loudin stated that Larox has, in the last 12 years, been selling pinch valves to replace knife gate valves in FGD units. He gave an example of the St. Johns River Power Plant that has replaced over 100 knife gate valves successfully with rubber lined pinch valves. The valves can be constructed in polycarbonate making the valve lighter.
Crane Valves – Werner Kremer
Werner Kremer discussed the wet FGD process which can have 350 to 600 valves. Valves have to be built to prevent corrosion and abrasion. Valves should reduce the amount of valve in contact with the wet products. Those parts in contact with wetted solutions should be made of Hastelloy, Duplex, and Hostalen GUD, a process developed by Crane. The first power plant with Hostalen was in Turkey in 1994.
Tyco Valves – Darrel DesRochers
Darrel DesRochers said Tyco has found that flow rates in piping systems for FGD units should stay below eight feet per second for best results. Conventional valves in slurry service tend to clog and leak. Conventional knife gate valves can clog, then the gate is subject to media and solids collect in ports. He also discussed other types of valves and their disadvantages and advantages. Clarkson slurry valves have rubber sleeves, gates outside the flow, and positive cycle. Clarkson valves range from three inches to 60 inches.
Bob McIlvaine
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