Turbine trip tests vary in more than speed and frequency. Nov 16, 2016 turbine overspeed events lead to costly and dangerous catastrophic failures. Incident 5 on 010198, a condensing steam turbine driving a water pump in the united kingdom failed during an overspeed trip test. Trip valves separate from the governor valves should shutoff the steam. Ahead of the control valves in series is a stop valve actuated by a simple, very reliable emergency governor, preferably called an overspeed trip. Asme 54887 steam turbine overspeed protection failures, causes, and strategies to avoid them. The turbine steam valves close and cut off the flow of steam to the turbine blades, causing the turbine to slow. Steam turbine control valve, governing and lube oil system subodh kumar tikadar general industrial steam turbine prefers a steam source of 42 kgcm2 600 psi at 482 oc 900 o f. The turbine was rated for 600 hp at 4643 rpm, with a steam inlet pressure of 40 psig. Overspeed detection and tripping are decentralized. This integrated trip block assembly is intended for use on mechanicaldrive or generatordrive steam turbines that use lowpressure 525 bar 73363 psi hydraulic trip oil headers. Controlling the turbine steam flow with a minimum pressure drop through the control valves is very important.
Heinzmann also offers a triple modular redundant overspeed trip unit to provide high integrity backup overspeed protection for turbine controls systems. Double and single extraction steam turbine generator digital fault tolerant control with direct steam rack electrohydraulic cylinder actuatorshydraulic power unit, instrumentation, turbine overspeed protection, power management controller, digital voltage regulator, vibration system and human machine interface touchscreen. The turbine inservice inspection and test program is used for the governor and overspeed. A multivalve, multistage turbine protection system incorporates a mechanical overspeed device trip pin to shut down the turbine on overspeed 10 percent above maximum continuous speed. In these situations speed increases rapidly above the design operating speed in such a manner that a unit is driven to. In systems with a low oilair pressure trip device, a solenoid. Two independent governors are needed for safe turbine operation. May 22, 2015 in 9183 december 20, 1991 page 2 of 3 when the autostop oil repressurized, the interface valve closed, and all turbine stop valves reopened allowing steam flow into the turbine. The electronic turbine overspeed protection system prevents excessive turbine speed that could lead to equipment damage. Steam turbine trip signal when gcb opens automation. Gcswoodward steam turbine controls,505,micronet,protech. Data and experiences of one insurance company in several areas failure for steam turbines were presented by clark 1. For gas and steam turbines, this means reliable detection of overspeed and immediate closing of the trip valve in response.
Modernization of overspeed detection man primeserv. Turbine overspeed events lead to the most dangerous and costly. Throttle trip valves provide effective flow control and emergency shutoff operation in a single, highly reliable valve assembly. If the mots trip system fails, the electrical overspeed trip system is automatically activated to trip the turbine at approximately 111. The full method of testing is described in section 3. The trip mechanism acts independently of the governor controlled system and closes the trip valve to stop the flow of steam to the turbine in the event of over speed condition.
Upgrading the turbine control and protection system at. Toshiba manufactures and supplies all forms of valve components, including valve stems, seats, and bushings. Steam turbine control applications electronic turbine overspeed protection the electronic turbine overspeed protection system prevents excessive turbine speed that could lead to equipment damage. Engineering design and application of the steam turbine and its.
Over the years customers have designated skinner as the driver of choice for their rotating equipment. As throttle valves, they are used to regulate flow of steam and gas in large, highpressure pipe lines, such as the main steam line serving a large, highpressure. Steam turbine overspeed trip mechanical engineering general. The modern steam turbine was invented in 1884 by charles parsons, whose first model was connected to a dynamo that generated 7. System components heinzmann australia is your single source partner, providing all system components for. Trip valves operate in the shut tripped or fully open position only. These versatile product families allow entire plantscompanies to use and standardize on one actuator family or ods family across their plants, lowering associated spare. The invention of parsons steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare. The turbine was experiencing downtime which required operations to valve out steam so a manual reset of the trip valve could be performed. Features of this option are firstout trip logic, median signal selection logic for critical inputs, and diverse overspeed trip that is testable on line.
Feb 28, 2015 the overspeed trip valve closed, but not fast enough to prevent a very severe overspeed. It is available in both tripleredundant mark v tmr and singlechannel mark v simplex control systems, the only difference being the two additional controllers in the tmr design. Ger3658d speedtronic mark v gas turbine control system. The new speedtronic mark v steam turbine control system is developed from this long evolution of electronic steam turbine con. The variation in load during the operation of a steam turbine can have a significant impact on its performance. The tg is designed to permit periodic testing of steam valves important to overspeed protection, electrical overspeed trip circuits and several other trip.
Standard features horizontally split casing builtup rotor construction center line support multiple shaft end configurations carbon ring steam end sparkproof, overspeed trip with independent trip valve. Overspeed trip testing of steam turbines gas compression. The flow of steam into the steam turbine is regulated by inlet control valves. Steam turbine over speed trip systems prem baboo sr. The normal governor raise button is used to increase speed to the trip setpoints. Jun, 20 a multi valve, multistage turbine protection system incorporates a mechanical overspeed device trip pin to shut down the turbine on overspeed 10 percent above maximum continuous speed. Properly functioning steam turbine valves and governors are critical to the successful operation of your power plant. The second, or main governor, usually controls speed at a constant rate. Combined cycle electric power plant and a gas turbine having an improved overspeed protection system. The speeddetector modules offer a unique and independent trip subsystem that allows hardwired overspeed protection to safety trip the turbine within 5 milliseconds from either the control system or.
Skinner s28 up to 2000hp steam turbine steam turbine. In a practical situation the load frequently varies from the designed or economic load and thus there always exists a considerable. 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. Combined cycle electric power plant and a gas turbine. A variety of valve actuator options are available from pneumatic, electronic, hydraulic, and electrohydraulic to suite your needs. A sil 3 electronic overspeed trip system is fi tted as standard. Less than adequate speed control often results in manual control or frequent operator intervention in order to overcome speed fluctuations. 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. Tmr over speed protection system gulf refinery governor. The protechtps is a safety plc with integrated overspeed protection designed to safely shut down any plant process equipment, engine, steam, gas, or hydro turbine upon sensing a safety event.
Consists of a springloaded pin or weight mounted in the turbine shaft on a collar, a quickclosing valve which is separate from the governor valve and interconnecting. The electrical overspeed trip system is described in dcd tier 2, section 10. Destructive overspeeding of steam turbines due to poor component design. Further we provide fully integrated panels for generator, compressor or pump applications with open software access and title to all software licenses transferred to the customer for plc systems. A multi valve, multistage turbine protection system incorporates a mechanical overspeed device trip pin to shut down the turbine on overspeed 10 percent above maximum continuous speed. Also discussed are redundant fail safe designs that will give maximum protection and reliability. The new speedtronic mark v steam turbine control system is developed from this long evolution of electronic steam turbine controls.
Protection of steam turbines using reliable solenoid trip. Features include redundant speed sensing, remote set point control as well as dual speed control dynamics and overspeed trip test capabilities. The modern overspeed detection system provides reliable protection of the steam turbine train against possible damages due to overspeed. Turbines are equipped with shutoff systems that are designed to.
Parts and functions of steam turbine power plant tutorials. In a reheat steam turbine, the same speed governor and emergency governor may also actuate respectively a set of intercept valves and reheat stop valves these having much the same control. Security trip systems an emergency trip is fi tted on each turbine to trip it in the event of any fault condition arising. Real time operating system rtos provides the software architecture to meet the. The tetrasentry is connected to the hydraulic trip header in parallel with the turbine trip valve. One solenoid valve installed in the control oil system exposes the turbine to a spurious trip if the solenoid should open. The protech 203 over speed protection system monitors three individual. However this is not allowed under electrical protection function operations. Actuators and control systems for turbomachinery voith.
Understanding and preventing steam turbine overspeeds by. Mechanical retrofit ccc compressor controls corporation. The quicktrips fault tolerant design makes it ideal for critical steam turbine applications, where turbine uptime and availability are essential. Sep 22, 2017 steam turbine mechanical overspeed trip devices outdated mechanical trip devices should be replaced. Overspeed protection for turbines cto a reliable overspeed protection system is indispensible for turbomachinery.
The ability to test the correct functioning of each turbine steam valve is necessary for both onload operation and also prior to runup. An overspeed failure on a big steam or gas turbine is one of the most. In 9183 december 20, 1991 page 2 of 3 when the autostop oil repressurized, the interface valve closed, and all turbine stop valves reopened allowing steam flow into the turbine. New generation of electrohydraulic steam valve actuation. In turbine applications where rugged and dependable performance with low capital investment is critical to your operation, the wise choice is a skinner s28 singlestage steam turbine. For simple single valve steam turbine applications where basic turbine control, protection, and monitoring are required, the 505 controllers integrated operator control panel, overspeed protection, and trip events recorder is it ideal. Designed for small steam turbine applications where overall system cost is a concern. Gcs was contracted to provide new control system and overspeed protection on all refinery api612 steam turbines. How steam turbine protection system works turbomachinery. This module also synchronizes the turbine generator to the power system. This results in closing all turbine stop and cvs, thus tripping the turbine. In balance, i would want to take a careful look and the whole steam cycle design, the directly connected auxiliary load, the control system design and logic, overspeed tolerance of the turbine, and the plants function and needs before deciding. The overspeed trip is the final protection against catastrophic failure of the turbine following a load rejection, causing the unit to become disconnected from the power system. However, it is believed that these improvement programs have not reduced steam.
Run the turbine up to about 75% speed and trip it manually. The protechgii is a configurable overspeed detection system designed to safely shut down steam, gas, and hydro turbines of all sizes upon sensing an overspeed or overacceleration event. 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. This turbine is equipped with an overspeed trip to protect. The electronics subsystem monitors the instrumentation subsystem, provides trip solenoid testing and turbine trip logic, and a communication link to the plant dcs for display in the control room. Steam turbine control having high quality control for the steam turbine ensures the process remains stable with the highest possible efficiencies as well as increased reliability. The testing is carried out on an unsynchronised turbine. If the turbine rotates in an overspeed condition, the increased centrifugal force extends the bolt outward until it hits a mechanical lever that results in releasing the hydraulic fluid pressure that operates the turbine steam valves. 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. As designed, the generator output breakers had opened upon receiving the reactor trip signal, so the steam flow through the unloaded turbine caused the turbine to. I recollect reading in a paper where the vendor was recommending using a bypass on the steam line for some reason to do a proper over speed test. Our steam turbines serve a vast range of industries ranging from food and sugar to biomass and textiles and beyond. Hello, i have seen various vendor oem recommendations on performing the plant overspeed trip testing on steam turbines. Additionally, an overspeed may be caused by a governor failure on an unsynchronised turbine causing an excessive steam demand.
Steam from the moisture separator reheaters enters the low pressure turbines after. This overspeed device safely shuts down steam, gas, and hydro turbines of all sizes upon sensing an overspeed or overacceleration event. A partial stroke test tripsim permits testing of the trip valve during turbine operation. The 5009 and 5009lst large steam turbines controls are designed to. The woodward peak 150 digital control is designed to control single valverack steam turbine driving a mechanical load. Sapphire ii dual redundant overspeed trip precise overspeed protection detection for optimum safety of steam turbine. As throttle valves, they are used to regulate flow of steam and gas in large, highpressure pipe lines, such as the main steam. Programmable control systems can be provided which initiate shutdown of the turbine in response to a variety of.
Feb 24, 2015 steam turbine over speed trip systems 6 1. One is an overspeed or emergency trip that shuts off the steam at 10 percent above running speed maximum speed. Most cv designs use a balancing arrangement to reduce this steam force. Available with two dualredundant trip relay outputs using 2outof3 voted architecture, or with three independent nonvoted trip relay outputs. To ensure optimum reliability of the trip system, use multiple solenoid control oil dump valves in parallel and in series, with online solenoid test facilities for each valve. Adjust the governor up until the overspeed trip mechanism trips the stop valve. The overspeed trip valve closed, but not fast enough to prevent a very severe overspeed. Jun 15, 2008 the only way to avoid the steam turbine overspeed is to close the steam turbine valves a couple of seconds before the gcb opens, to discharge the steam present in the steam valve chambers in usable power rather than in overspeeding the steam turbine.
Failure of two of the three primary speed control signals results in a turbine trip. Ger3687c speedtronic mark v steam turbine control system. Any pressure drop caused by the steam flow through the co trol valves is a loss of thermodynamic energy. Steam turbine governing is the procedure of controlling the flow rate of steam to a steam turbine so as to maintain its speed of rotation as constant. Case rmc trip block system the case rmc tbs offers manual, semiauto and automated testing options. Oct 19, 1971 ahead of the control valves in series is a stop valve actuated by a simple, very reliable emergency governor, preferably called an overspeed trip. Available in two dual redundant trip relay outputs using a 2outof3 voted architecture, or with three. The electronic overspeed trip system increases turbine safety by reliably shutting down the turbine should an overspeed event occur.
Whatever the requirements are, we provide either bare steam turbine drivers to oems, or we supply complete packages including gears, lube oil systems and controls. Instruction manual for single stage 350, 500, and 700 frame steam. Msr control the msr regulates the main steam flow, thereby controlling. These include control of liquid, gas or both fuels in. The protection system monitors steam turbine total train parameters and ensures safety and reliability by the following action. As the shaft rotates, the tip of the trip pin will hit a mechanism that actuates the spring of the trip valve and then trip valve closes the inlet steam line. The trisen tetrasentry is a dual parallelredundant hydraulic trip block thats online testable and online repairable. A separate independent trip valve or combined trip and throttle valve, as specified by the purchaser, shall be provided for each steam inlet. 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. Synchronization is backed up by a check function in the three control processors. This is a costeffective solution for both new equipment and when retrofit to existing equipment. Low pressure turbines each of the three low pressure turbines is a dualflow, reaction, condensing turbine. The trip mechanisms on most turbines are required by law to be.
Elliott yr steam turbines are rugged and reliable pieces of precision turbomachinery. 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. The ability to test the correct functioning of each turbine steam valve is necessary for both onload operation and also prior to run. Woodward control system upgrade and control system. 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. Uncontrolled acceleration of the turbine rotor can lead to an overspeed trip, which causes the steam control valves that control the flow of steam to the turbine to close. Steam turbine mechanical overspeed trip devices aig. Millstone power station, unit 2, revision 36 to final. It accurately monitors turbine rotor speed and acceleration via active or passive magnetic pickups mpus and issues a shutdown command to the turbines trip valves or corresponding trip system. Singlevalve, singlestage elliott yr turbines have a worldwide reputation for. The voith cto overspeed protection system provides both functions in a single device. The mark v control system is designed to fulfill all gas turbine control requirements. Overspeed testing to prove the actual value of trip setpoint of overspeed protection systems is an essential subsidiary function of governing systems.
Dresserrand steam turbines steam turbines currently are operating. For improved steam consumption, elliott designed the multiyr. Steam turbine control valve, governing and lube oil system. An overspeed failure on a big steam or gas turbine is one of the most frightening industrial accidents. Steam turbine modernization system integration peaker. Elliott myr turbines are available up to 12,000 hp 8,950 kw. Dresserrand steam turbines a siemens business steam.
Steam turbine control ccc compressor controls corporation. If this fails then the turbine may continue accelerating until it breaks apart. 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. The following requirements must be considered in the system design. Introduction if the overspeed trip protection of a steam turbine fails to function at the design set speed, turbine buckets or a section of a. Case rmc trip block system wunderlichmalec engineering.