ASME TDP-1-2006 pdf download
ASME TDP-1-2006 pdf download.Recommended Practices for the Prevention of Water Damage to Steam Turbines Used for Electric Power Generation.
The valve may be automatic or remote manual, with actuation initiated by the control system automatically (automatic valve) or by the operator manually from the control room.
steam generator: the equipment that provides heat to turn feedwater into motive steam and also reheats the steam in a reheat cycle. In a conventional steam generator, the heat is produced by the burning of fuel (usually coal, oil, or gas). In an HRSG, the heat comes from the exhaust of an external heat source such as a gas turbine, sometimes supplemented by the burning of additional fuel in the gas turbine exhaust. Drum-type steam generators employ a large drum to separate steam from the water as it boils in the tubes. The drum accommodates the increase in volume resulting from the water’s conversion to steam, which is then taken from the drum through a section of superheating tubes to obtain the temperature needed at the main turbine. In the once-through type of steam generator, which does not use a drum, the feedwater is converted to motive steam conditions as it passes directly through the tubes.
2.2.4 Control System
integrated control system (ICS): a control system featuring multiple processors, input/output (I/O) modules, and memory storage interconnected through a communication network and equipped with redundant power supplies. Normally, a distributed control system (DCS) or redundant programmable logic controllers (PLCs) will meet this requirement.
The minimum ICS features to meet the reliability and redundancy needs addressed in this Standard are as follows:
(a) dual processors
(b) uninterrupted power supply
(c) 1/0 associated with redundant plant equipment and instruments should not be connected to the same I/O cards
(d) outputs that fail to known position during processor or internal communication failure
local control system: a control system that allows control of the final control element from a location in the vicinity of the primary element or the final control element.
transmitter select: the ICS programming should be designed to handle instrument failures safely. The transmitter selection programming should follow a safe progression of selection steps in the event of failure of each transmitter as shown below. A failed transmitter or switch should produce a trip signal for the two-out-of- three trip logic.
The following examples illustrate this principle using high level conditions:
(a) Three-Transmitter Select (Example)
(1) zero transm itters failed (normal operation): median select of good signals.
(1) zero transmitters failed (normal operation): high select of two good signals.
(2) one transmitter failed: remaining good transmitter selected (one of three trip signals).
(3) one transmitter failed and high—level switch alarm:
remaining good transmitter selected and two out of three protective trips.
(4) two transmitters failed: level controllers revert to manual, hold last good controller output, and two out of three protective trips.
2.3 Symbol Legend
See Table 1 for symbol legend to be used for reference to figures.
2.4 Device Identification Letters
See Table 2 for a list of device identification letters.
2.5 References
The following is a list of publications referenced in this Standard.
ANSI/ISA 5.1-1984 (R1992), Instrument Symbols and Identification
Publisher: Instrument Society of America (ISA), 67 Alexander Drive, Research Triangle Park, NC 27709
CS-2251, Recommended Guidelines for the Admission of High-Energy Fluids to Steam Surface Condensers
Publisher: Electric Power Research Institute (EPRI), 3420 Hiliview Avenue, Palo Alto, CA 94304
Standards for Closed Feedwater Heaters, Fifth Edition
(1992)
Standards for Steam Surface Condensers, Ninth Edition (1995 or latest edition)
Publisher: Heat Exchange Institute (HEI), 1300 Summer Avenue, Cleveland, OH 44115-2815
3 DESIGN RECOMMENDATIONS
This section outlines specific recommendations for the design of the systems listed. These recommendations are intended to represent a conservative design for protection from water induction. There is no intention to supersede any existing codes or governmental regulations.
