Hga excess air discharge flue gas temperature main steam condition reheat back pressure lhv. Instruction manual for single stage 350, 500, and 700 frame steam turbines manual 107a. The highpressure steam from the boiler is expanded in nozzles to create a highvelocity jet of steam. The voith cto overspeed protection system provides both functions in a single device.
C61207 this standard specifies the minimum requirements for. Turbine overspeed events lead to the most dangerous and costly of catastrophic turbine failures. Report turbinegenerator overspeed protection systems. Hello guys, i would like to know if there is any recommendationguide or norm that indicates which is the frequency to carry out the overspeed trip tests for sp steam turbine overspeed trip mechanical engineering general discussion engtips. In the simplest form the overspeed protection system must detect when operating speed is exceeded by a designated percentage often 10% to % and must initiate successful closure of all valves to isolate any and all potential steam energy sources. Also discussed are redundant fail safe designs that will. Aug 05, 2016 an overspeed failure on a big steam or gas turbine is one of the most frightening of industrial accidents. State thedifference between latchedand unlatchedronbacks. An overspeed failure on a big steam or gas turbine is one of the most frightening industrial accidents. Proceedings of the 2012 20th international conference on nuclear engineering and the asme 2012 power conference. The trip mechanisms on most turbines are required by law to be. The plant features a tandemcompound, doubleflow, reheat steam turbine generator. General electric systems technology manual chapter 3.
Ger3582e steam turbines for stag combinedcycle power. Steam turbine valve configurations can be all in one body or as individual valves for the large units, for the main stop throttle and control functions for each section of the steam turbine. Cary reliability superintendent tosco refining company, avon refinery martinez, california john b. The gas turbine vendor chooses an overspeed trip setting to avoid reaching this maximum speed. Speedtronic mark v steam turbine control system introduction the speedtronic mark v is the latest version of ges long series of highly reliable electrohydraulic control ehc systems for steam turbines. Overspeeding of turbine rotors as it pertains to time lag of the overspeed devices and the amount of energy stored between the trip valve and the exhaust of the turbine is addressed. An example is a stag 109e ms, indicating that the combinedcycle contains a single frame 9e gas turbine generator and a separate ge steam turbine generator on two different shafts.
Turbine overspeed events lead to costly and dangerous catastrophic failures. Understanding and preventing steam turbine overspeeds by. The axial split casing allows easy access for onsite inspection and repair. If a turbine is determined to be in a critical service, a fault tolerant overspeed trip system should be utilized. The performance of the steam turbine is governed by the losses occurred in it. Bypass valves bpvs to open wider, accommodating the increased steam production. Steam turbine overspeed trip mechanical engineering. Figure 1 is a schematic drawing of a steam turbine provided with an overspeed trip mechanism. The subsequent acceptance tests serve as an example for the application of generalized correction methods. Examples based on real turbines will be used to compare the differences between. For gas and steam turbines, this means reliable detection of overspeed and immediate closing of the trip valve in response.
Preventing overspeed has always been the primary focus for turbine safety design now, as the industry has become more aware of the need for a more comprehensive approach to turbine safety, a refinement is underway thats reflected in recent changes to industry standards such as api612 specialpurpose steam turbines for petroleum, chemical. We offer an inventory of specialty spare parts and short cycle delivery. Speedtronic mark v steam turbine control system introduction the speedtronic mark v is the latest ver. Examined more closely herein are the characteristics of a steam turbines components and evaluation as to possible involvement in loss of control of a machine. Steam turbine mechanical overspeed trip devices aig. Asme 54887 steam turbine overspeed protection failures, causes, and strategies to avoid them. The overspeed trip test consisted of allowing the turbine to accelerate to a maximum rpm speed to test a mechanical shutoff valve. A multivalve, multistage turbine protection system incorporates a mechanical.
Overspeed, which may occur following steam turbine unloading events, can be the result of a transient rotational speed spike caused by delay in system dynamic and control system lag as the turbine s control system assumes new control positions. Optionally, a system with a mechanical overspeed governor can be supplied. Summary of the key concepts the load limiter restricts the maximum allowable turbine generator load. At present, the majority of russian steam turbines are equipped with a hydromechanical system for pro tection from an inadmissible increase of rotation fre. The protection and control system of boiler, turbine and generator which is a very sophisticated system involving modern technologies, is of utmost importance in any thermal power plants. The myr design combines the reliability and parts interchangeability of our popular yr turbine with the power and efficiency of multistage turbines. Overspeed trip systems of steam turbinegenerator units asme. Control of thf steam flow to the nozzles depends on the turbine itself. Overspeed the turbine to check the overspeed trip visually inspect the turbine generator string for. Steam is reconverted to water when its work on the turbine is done, the steam is drawn into. Instruction manual for single stage 350, 500, and 700 frame. Sep 05, 2016 steam turbine repair time lapse video duration. Figure 2 does not show manual trips or trip overrides for testing. It is becoming common to find steam turbines that have been or are being.
The subsequent acceptance tests serve as an example for. However, the inspection and maintenance of these valves is critical. Three overspeed trip tests were required before returning the steam turbine into operation. Below are excerpts from the paper, turbine overspeed systems and required response times by scott l taylor of woodward and sheldon s smith of. State a typical ilulge ofnmbackrates expressed as a per centageoffull powerper second. Evidence of steam, oil or water leakage evidence of steam deposits proper position of all valves proper oil level condition of all control and trip linkages condition of. Below are excerpts from the paper, turbine overspeed systems and required response times by scott l taylor of woodward and sheldon s smith of american. The mechanical shutoff valve was designed to cut off the flow of steam to the turbine at the maximum rpm and thereby. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple. Instruction manual for single stage 350, 500, and 700. Its heritage consists of a long list of successful control systems, including the first ehc mark i steam turbine control built in the. Benefits the modern overspeed detection system provides reliable protection of the steam turbine train against possible damages due to overspeed.
Known steam turbines can be equipped with trip systems that can prevent steam turbine speed from exceeding a defined overspeed value. In its simplest form, a steam turbine consist of a boiler steam generator, turbine, condenser, feed pump and a variety of auxiliary devices. This turbine is equipped with an overspeed trip to protect. Reducing reactor power decreases reactor vessel pressure and turbine throttle pressure figure 3. Operating experience indicates that the frequency of turbine overspeed events is higher than previously thought and that the. The turbine steam flow would increase, causing unloading to recur again. It is becoming common to find steam turbines that have been or are being upgraded with new controls andor related shutdown systems. As abeltio noted, an overspeed trip setting of 110% of rated speed is quite common for large indutrial gas turbines in power generation service.
Trip valve response monitor sil3 steam or gas turbine overspeed. Steam turbines are operated in different applications as mechanical drives for compressor trains or as generator drives for power generation. The myr produces more power without additional steam, and can be installed in many areas where singlestage steam turbines currently are operating. Api 616 overspeed trip setpoint specification machines. Approval issue module 2347 the turbine governing system. Overspeed, which may occur following steam turbine unloading events, can be the result of a transient rotational speed spike caused by delay in system dynamic and control system lag as the turbines control system assumes new control positions. This increase in turbine steam flow compensates for the reactor vessel pressure rise, and increases generator output. Us20120151922a1 steam turbine overspeed protection. Aeods study provides insight into the shortcomings in the design, operation, maintenance, testing, and human factors associated with turbine overspeed protection systems. How steam turbine protection system works turbomachinery. Steam turbine valves are the most important components before a steam turbine for the admission and control of steam flow. In general, a steam turbine is a rotary heat engine that converts thermal energy contained in the steam to mechanical energy or to electrical energy. The steam turbine is a device for obtaining mechanical work from the energy stored in steam.
Pdf protection and control of steam turbine generator. The modern overspeed protection system for steam turbines of the. To aid this system, steam is taken from the high pressure steam line ahead of the governor valves and routed to the inlet to the lp turbine. Turbine is turned by steam turbine shaft turns due to high pressure of steam pushing against series of giant turbine blades. Electronic overspeed protection systems provide safe, simple, and reliable testing. The plant features a tandemcompound, doubleflow, reheat steam turbinegenerator. Whether steam or combustion driven, your turbinegenerator needs to be ready and personnel need to be ready. Steam turbine overspeed protection failures, causes, and strategies to avoid them. A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Steam turbine valves are typically so reliable they are often overlooked. Steam turbine control basics overspeed prevention is best accomplished by not losing contra, of the turbine. Oneonone configurations are further qualified as being multishaft ms, or single shaft ss. Failure to perform timely inspections and maintenance can lead to.
An overspeed failure on a big steam or gas turbine is one of the most frightening of industrial accidents. Woodward also offers different sizes of steam turbine valve actuators and turbine overspeed detection systems ods for selection and application by both oems and endusers. Steam turbine overspeed protection failures, causes and. This paper discusses the design, history, current standards and designs, and the relation between turbine overspeed and the time constant of rotors. The trapped steam between the trip valve and throttle valves has sufficient energy to accelerate the turbine rotor beyond its design limits. Modernization of overspeed detection man primeserv. Steam turbine performance 3 4 2 1 46 45 44 43 42 41 43 42 41 40 39 % % 1. Overspeed protection for turbines cto a reliable overspeed protection system is indispensible for turbomachinery.
The steam turbine overspeed event occurs when little or no energy is being consumed by the driven equipment, whether a generator, pump or compressor, and too much steam is provided to steam turbine. Operators guide to general purpose steam turbines wiley. This cooling steam keeps a positive direction of steam flow through the lp turbine stages which helps to remove the windage heat. Course 234 turbine and auxiliaries module seven approval issue pagel8 7. The protection system operates only when any of the control system set point parameters are exceeded, and the steam turbine will be damaged if it continues to operate. His expertise is in the field of rotating equip ment, hot tappingplugging, and special problems. Coupling breakage under load conditions can cause steam turbine overspeed and blades to exit through the exhaust case, even though the overspeed trip system is set correctly and functions properly. This code is applicable to steam turbine generator units of 500 kw and larger and provides. Charlie rutan is senior engineering advisor engineering fellow, a position that is a shared resource with lyondellequistar, in alvin, texas. Coppus rlha steam turbines the rlha turbine is an axial split horizontal turbine with split sleeve bearings, available in 4 frame sizes offering up to 4,000 hp 2,980 kw. He currently oversees the ac tivities of the metallurgical inspection department and the mechanical equip.
Traditionally, overspeed protection systems were designed and provided by the original equipment manufacturers oemsfew options were available either in terms of testing or modifying these systems. Therefore the overspeed system has to be periodically tested to ensure the system has the adequate response time to protect the turbines, plants and personnel. Steam turbine valve testing, inspection and maintenance to. Destructive overspeeding of steam turbines due to poor. The high cost of an extensive overhaul due to an undetected component failure. Evidence of steam, oil or water leakage evidence of steam deposits proper position of all valves proper oil level condition of all control and trip linkages condition of instrumentation, conduit, wiring, insulation, etc. Steam turbine overspeed protection failures, causes, and. Ger3687c speedtronic mark v steam turbine control system. Data and experiences of one insurance company in several areas failure for steam turbines were presented by clark 1.
Figure 2 is a sectional side elevation of a small part of the turbine shaft shown in figure 1, near the end of the shaft which is not coupled to the load, and which is indicated by the numeral ii in figure 1. Its modern manifestation was invented by charles parsons in 1884 the steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, which results. Steam turbine solutions 05 customised steam turbine generator sets solutions built to deliver a competitive advantage for power generation applications peter brotherhood provide a complete package comprising the turbine, gearbox, generator, instrumentation, control and monitoring systems and associated auxiliary equipment. Calculation of the maximum rotor speed during an overspeed. The steam turbine overspeed event occurs when little or no energy is being consumed by the driven equipment, whether a generator, pump or. In addition to the two major protection systems mentioned above, other typical protection systems for a rotating. What is steam turbine description and characteristics. As abeltio noted, an overspeed trip setting of 110% of rated speed is quite common for large.
The timetested reliability of the rlha turbine makes it an ideal. Unlike with reciprocating engines, for instance, compression, heating and expansion are. A major steam turbine repair can cost ten or more times that of a garden variety centrifugal pump repair. Steam turbine valve risk exposure steam turbine valves must be considered safety critical background. Sep 22, 2017 steam turbine mechanical overspeed trip devices outdated mechanical trip devices should be replaced. Background the steam turbine overspeed event occurs when little or no energy is being consumed by the driven equipment, whether a generator, pump or compressor, and too much steam is provided to steam turbine.
Us20120151922a1 steam turbine overspeed protection method. The turbine shaft is connected to the generator shaft, where electricity is produced when magnets spin within wire coils. Asme 54887 steam turbine overspeed protection failures, causes, and strategies to. Steam enters the turbine with a high energy content and leaves after giving up most of it. This system is adequate if the loss of the turbine and the equipment driven by the turbine does not result in a significant upset andor pose a safety hazard andor damage the environment. Electronic overspeed systems are very reliable, and come with modern features such as a testable set point and speed rate of change detection. General purpose steam turbine reliability by john b. Steam turbine overspeed trip mechanical engineering general. Jun, 20 the function of the steam turbine protection system is often confused with the control system, but in fact the two systems are entirely separate. Cary is the reliability su perintendent with the tosco refining company. Api standard 612 petroleum, petrochemical, and natural gas industries. The surge system has been previously discussed, the turbine overspeed system will be discussed later in this chapter.
These versatile product families allow entire plantscompanies to use and standardize on one actuator family or ods family across their plants, lowering associated spare. Nov 16, 2016 turbine overspeed events lead to costly and dangerous catastrophic failures. Instruction manual for single stage 350, 500, and 700 frame steam. Additionally, an overspeed may be caused by a governor failure on an unsynchronised turbine causing an excessive steam demand. Field adjustment of a mechanical overspeed governor can be a risky and costly exercise. A turbine overspeed accident can be caused by a lightninginduced power surge, a fouled pilot valve, an electrical fault, operator failure, or any of a few dozen other problems. This steam turbine controller includes specifically designed algorithms and logic to start, stop, control, and protect industrial steam turbines or turboexpanders, driving generators, compressors, pumps, or industrial fans. This tutorial will focus on what turbine response times are required to adequately protect turbines of all sizes.
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