Fisher™ TBX combines pressure and temperature control in a single valve; helps avoid costly damage, and prevents start-up delays, excessive noise and vibration
Emerson Process Management has introduced to Europe the Fisher™ TBX steam conditioning valve, which combines precise pressure and temperature control in a single turbine bypass valve. The Fisher TBX is designed to optimise operating performance and reliability in the most severe steam applications, avoid potential damage to steam turbines or boilers, prevent start-up delays, and increase plant efficiency.
Turbine bypass applications in cycling power plants demand the highest levels of valve reliability and performance. The Fisher TBX meets those expectations with technology to solve noise, vibration, sticking, leakages and pressure/temperature control challenges. Its self-diagnostic capability helps to maintain peak performance and prevent unexpected problems.
“Increased energy costs and the desire for more efficient cycling power plant operation requires better control of steam conditions,” said Benoit Wagner, Europe Engineering Director of Emerson’s Fisher Valves and Instruments business. “The Fisher TBX has been designed to enable efficient control of steam pressure and temperature, providing optimised performance supporting the daily cycling of a power plant.”
The rugged cage-guide design of the Fisher TBX enables it to handle full main steam pressure drops, while Whisper Trim™ technology eliminates the risk of excessive noise and vibration, which could cause structural damage and performance degradation. The valve’s proven and well-established Whisper Trim III cages and WhisperFlo trims help to attenuate noise by up to 40 dBA.
The Fisher TBX uses a thermally compensated hung trim design which accommodates rapid changes in temperature – as experienced during a turbine trip – to enable smooth, continuous operation. The cage is hardened for maximum life and can expand freely during thermal excursions. This prevents the valve plug from sticking and therefore avoids delays in turbine start-up. To prevent leakages affecting steam production when the turbine is operating, the Fisher TBX uses Fisher Bore Seal Trim technology, which achieves tighter shut-off.
Atomisation and vaporisation are key elements in any steam conditioning application. For efficient and effective temperature control, the Fisher TBX incorporates a manifold of variable geometry type AF nozzles which inject a fine mist into the downstream flow pattern. These nozzles are placed strategically, based upon extensive computational fluid dynamic (CFD) analysis, and their efficiency has been validated by field performance feedback. By reducing both temperature and steam pressure, the valve protects the reheater tubes, condenser and piping.
The typical Fisher TBX valve assembly includes a Fisher FIELDVUE™ DVC6200 digital valve controller. The FIELDVUE instrument’s diagnostic capabilities enable the valve to be monitored remotely and help maintain peak performance, without surprise failures. By comparing the present valve/actuator signature against previously stored signatures, operators can spot emerging performance problems, pinpoint a probable cause and take corrective action before the process is affected, potentially without leaving the control room.
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