Gas Turbine Efficiency - overcoming your power problems

VALVESValves for power systems -what’s new and what’s hot?[Above] 3-way valve schematic.Used extensively in extraction lines from steam turbines, feedwater heaters, heatingsystems, process equipment, lines from heat exchangers, valves form an essential part oftoday’s energy production systems, reports Schutte & Koerting.Ask any power systems engineer andhe or she will tell you that valvescan be the Achilles’ heel of anyequipment. That’s why you’ve got tochoose the best.Let’s consider four of the industry’sleading valve designs in relation to theirfunctions.Dual Plug Valves are primarily used todivert, restrict or completely shut offflow in oil cooler in power plantapplications. Pressure Relief Valves arequick-opening, quick-closing valves usedto protect equipment from gas pressurebuild-up or pressure surges.Check Valves have been developed toprevent backflow in steam, air, or waterlines. These are used extensively inextraction lines from steam turbines,feedwater heaters, heating systems,process equipment and lines from heatexchangers and auxiliaries.In the example pictured below, theThrottle Trip Valves made by Schutte &Koerting are dual-function valves designedto control the flow to steam turbinesThrottle Trip Valves provideeffective flow control and anemergency shut-off facility.during start-up and shut-down. Theseprovide emergency protection by closingautomatically and instantaneously when atrip condition is detected). Throttle TripValves provide effective flow control andemergency shut-off operation in a single,highly reliable valve assembly. As throttlevalves, they are used to regulate flow ofsteam and gas in large, high-pressure pipelines, such as the main steam line servinga large, high-pressure turbine or aturboexpander gas supply line.As trip valves, they add a measure ofsafety critical to these applications,without the expense of a separate tripvalve. When tripped either manually orautomatically, the valves rapidly shutdown flow to protect valuable equipment.S&K Throttle Trip Valves feature aninternal pilot valve arrangement torelieve pressure on the main disc as thevalve is opened.The seal-welded seat ring is shrink-fittedto the body and includes an expansiongroove, to prevent distortion of theseating face. Durable materials improveperformance and reduce wear.Flexitallic-type gaskets provide positivesealing at all cover joints, designed forsimple on-line adjustment of the yoke andlatching assembly.Optional ball bearing, threaded spindleand latching mechanisms are available toprovide mechanical assist for reliable lowfrictionoperation. Venturi seats can beprovided in high-pressure applications,reducing space requirements and allowinguse of smaller operators.Valves may be specified with weldedends or ANSI flange connections for directconnection to steam turbines.Three-Way Valves are primarily designedto handle high pressure applications suchas boiler feedwater service in steamDual function valvesare designed tocontrol the flowto steam turbinesduring start-up andshut-down. Made bySchutte & Koertingthis item adds ameasure of safetycritical to theseapplications,without theexpense of aseparate tripvalve.power plants. Three-Way Valves alsoprovide a convenient and economicalmeans of diverting flow from one pipelineto another. They are often used in bypassarrangements in steam generating plantsand process applications where they cansave users a great deal of money byeliminating conventional gate valves,bypass accessories and customfabrications.WIPInternet linkwww.s-k.comS&K 3-wayvalve.W ORLDWIDE I NDEPENDENT P OWER • MARCH 201031