Reducing cycling damage to combined cycle steam turbines. The actuator ofalarge turbine steam valve must generate large forces that are required10 overcome forces exerted by the steamflow and friction in the valve stem seal. Chapter 6 addresses the selection and use of special control valves. Major losses have occurred from the failure of these other critical valves to properly function as well. There are many considerations to be taken when choosing a controller. Properly functioning steam turbine valves and governors are critical to the successful operation of your power plant. Steam turbine inlet valves are used to control the power output of steam turbines for power generation. Experimental study of steam turbine control valves d zhang, a. To achieve this control of steam turbine speed, it has been the practice to provide steam valves for controlling steam flow from a highpressure steam turbine to a lowpressure steam turbine, these valves being individually actuated in response to power plant conditions. The portfolio includes pneumatic valve actuators, piston actuators, spring diaphragm actuator, and multispring actuators to improve actuation capability, simplicity and safety. This increase in turbine steam flow compensates for the reactor vessel pressure rise, and increases generator output. Any customer looking to upgrade will have a governor system tailored to their specific needs to guarantee satisfaction, ensure a reliable installation process and maximize turbine control reliability. Chapter 9 contains information on control valve standards and approval agencies across the world.
In 1999, analysis of a reported control valve failure was initiated, eventually requiring both analytical and specialized 99 elimination of flowinduced instability from steam turbine control valves by jim hardin senior. Turbines steam flow depends on steam pressure and size of input area through which steam enters turbine. An inventory of disc springs, seals and retainers is maintained to satisfy shortcycle turnaround requirements. It is clear that inspection and maintenance of all steam turbine critical valves protecting steam turbine generator sets from sudden massive destruction must be well reasoned and timely. Throughflow capability and flow stability of some steam turbine control valves were studied by experimental investigation and numerical simulation. The flow rate of steam is monitored and controlled by interposing valves between the boiler and the turbine. Steam turbine control valves are generally a high source of noise, as described by araki, et al. V ib f vl m u failures, as described by johns, et al. Steam turbine is heat engine, here steam energy is transferring into kinetic energy after passing through steam. Metso solutions for steam turbine manufacturers reliable valve partner for all steam turbine applications metso has a strong understanding and long experience in valves for steam turbine applications. Our experience is complemented by an extensive range of power oriented products including interstage attemporation desuperheaters, boiler feed control valves, boiler feed pump recirculation valves with soft seat class vi shutoff, blow. Parts and functions of steam turbine power plant tutorials. Maintenance and overhaul of steam turbines wgp42 05. Man primeserv has enhanced the steam control valves of type dgdkdegdek steam turbines to significantly increase availability and reliability.
Steam parameters refer to the pressure and the temperature of the steam. Therefore, there are two operational modes in general. The turbine speed is controlled by varying the steam flow through the turbine by positioning the governor valve. 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 turbine or a turboexpander gas. These valves may be subject to vibration under certain operating conditions, especially in. There is typically a main stop valve and a control valve in series. In the turbine bypass station, steam temperature must be reduced to protect downstream components from high temperatures and pressures. Steam turbine governing is the procedure of monitoring and controlling the flow rate of steam into the turbine with the objective of maintaining its speed of rotation as constant. Lubrication of the steam turbine is required to minimize the rotating friction in the bearings as well as to cool the bearing surfaces. Spx provides a wide range of valves for the control of pressure, temperature and flowinduced noise in all types of power plants. During startup andor turbine trips, the steam dump control valves control. Pdf on jan 1, 20, changjie yin and others published study on valve management of deh for steam turbine find, read and cite all the research you need on researchgate. Steam turbine valves are typically so reliable they are often overlooked.
The study and its findings are described in an epri report entitled operational and control strategies for reducing steam turbine damage from cycling combined. State of the art manufacturing, engineering and repair facility. As a market leader for industrial steam turbines, we offer a comprehensive range of reliable and versatile steam turbines for the power output range from 2 to 250 mw. Documented functional testing of your actuator assures a seamless transition to system operations. Pdf study on valve management of deh for steam turbine.
Each hp stop valve contains a permanent steam strainer to prevent foreign matter from entering the control valves and turbine. Valves that were reliable in many applications for many years might turn out to be inadequate for the new, higher pressures. Pressure reduction is accomplished by a multistage lownoise trim within the valve. Fisher superheat spray valves accurately control the amount of water injected into the steam attemperator or cooler, providing optimal main steam temperature control and stability. Ger3706d steam turbines for industrial applications. The steam turbine is designed with three distinct operating regimes. Steam turbine valve risk exposure steam turbine valves must be considered safety critical background. Advanced steam turbine controls mechanical drives a petrotech, inc. All valve components are manufactured to oem specifications. Consists of springopposed rotating weights, a steam valve, and an interconnecting linkage or servo motor system. However, the inspection and maintenance of these valves is critical.
Approval issue module 2347 the turbine governing system. In both the noncondensing and condensing type units, a single or double controlled extraction may be considered, depending on the number of openings that steam exits the turbine prior to the exhaust figure 6. Products include severe service and general service control valves, variable orifice desuperheaters, raven trim and steamconditioning valves and nuclear control valves, as well as custom designed speciality valves. For well over a century masoneilan has been synonymous with innovation, leading technology and responsiveness to market needs. Because of the convergingdiverging conguration of the valve passage, venturi valves. Valve positioning must be accurate for adequate control. Our turbine valve service group specializes in steam and combined cycles turbine control, stop, throttle, and intercept valves. By deciding to make an upgrade now, elliott can plan. It routes high pressure and high temperature steam around the hp turbine, from the main steam line typically to the cold reheat line. Some aspects of numerical simulation of control valves for steam. Chaplin encyclopedia of life support systems eolss the flow of high pressure steam entering the turbine is controlled by governor valves and stop valves. Baker hughes offers a variety of valve actuators suitable for a wide range of applications. Turbine s steam flow depends on steam pressure and size of input area through which steam enters turbine. Steam turbine control valve and actuation system modeling.
Using these valves provides ges customers with process. Parts and repair services steam turbine solutions inc. Experimental study of steam turbine control valves d zhang 1, a engeda1,jrhardin2 and r h aungier2 1turbomachinery laboratory, michigan state university, east lansing, michigan, usa 2ebara group, elliott turbomachinery company inc. In solving todays challenges and looking forward to. In doing so, the hp turbine bypass valve must perform both, pressure reduction of the life steam as well as temperature control. The pressure control system signals the turbine control valves tcvs andor bypass valves bpvs to open wider, accommodating the increased steam production. Steam turbine control systems are being designed with todays technology to operate a turbine in a safe and reliable manner. White paper experience capability execution stc mechanical drivewp page 3 of 5 petrotech steam turbine control ler stc the petrotech stc manages the operation of the steam turbine from issuance of the start command all the way. Schofield ge company schenectady, ny introduction the need to provide stateoftheart products for a diverse and everchanging market is the chal lenge facing steam turbinegenerator manufactur ers in the 90s. Combined stop and intercept valve for steam turbines. In a control valve a great deal more energy is lost to friction than in a. Control valves are not as efficient as nozzles in changing heat into kinetic energy. Control steam with greater efficiency and accuracy.
Units power is generally controlled by manipulating of steam flow through turbine. Chapter 9 includes information on control valve standards and approval agencies throughout the world. The former control the flow to ensure that the appropriate amount of. Depending upon the particular method adopted for control. This prevents damage to the turbine and results in efficient turbine operation. Main steam control valve the main steam control valve modulates flow of admission steam to the hp turbine from the hrsg or boiler. Typically, the high noise occurs mostly at high pressure drop, with or without shock. Haraguchi, in advances in steam turbines for modern power plants, 2017.
With its breadth of products and services, unequaled global presence and advanced process control expertise, masoneilan is uniquely positioned to be the leading provider of control valve solutions. Our industrial steam turbines are designed for easy constructability, fast startup and economical operation. Dimensional analysis and lower half control valve seats. Failure to perform timely inspections and maintenance can lead to. The trs turbine valve service group can provide you with help and assistance with a variety of your plant needs. Fundamentals of inlet control va lves the flow of steam into the steam turbine is regulated by inlet control valve s. Steam turbine control valve and actuation system modeling for.
Governor systems are speedsensitive control systems that are integral with the steam turbine. Live steam control valves are key components for the operation of steam turbines. Understanding and preventing steam turbine overspeeds by. Nozzle control governing of steam turbine is basically used for part load condition. General electric systems technology manual chapter 3. Rapid closure of the control valves when the turbine trips provides redundant isolation of the steam flow to the high pressure turbine. Steam turbines startups 171 prior to switching on the turning gear, oil system is started up. Steam turbines startups the szewalski institute of fluid flow machinery, polish academy of sciences. Toshiba manufactures and supplies all forms of valve components, including valve stems, seats, and bushings. They are usually designed and manufactured by the steam turbine oem. Chapter 7 covers desuperheaters, steam conditioning valves, and turbine bypass systems. Some set of nozzles are grouped together may be two, three or more groups and each group of the nozzle is supplied steam controlled by valves. Introduction in steam turbine st control and actuation, the steam control valve plays a key role in two main areas.
In the turbine governor the target rotational speed 3000 rpm is set as well as runup rate. Control valve sizing for steam systems spirax sarco. The aim of this study was to generate concepts for steam turbine inlet control valves designed for higher pressure and temperature in comparison with the present design. Controlling the turbine steam flow with a minimum pressure drop through the control valves is very important. Fundamentals of inlet control va lves the flow of steam into the steam turbine is regulated by inlet control valves. Woodward offers steam turbine controllers for all size turbines and applications. Turbine bypass systems 2 copesvulcan hp and lp bypass valves prior to shipment to india. Pdf investigation on flow characteristics and stability of. Unesco eolss sample chapters thermal power plants vol. Chapter 6 covers the selection and use of special control valves. The paper describes a study conducted on steam turbine control valve and actuation systems, which rule the machine final power production and rotational. Abstractbecause of the convergingdiverging configuration of the valve passage, venturi valves have been widely used in large turbines to regulate inlet flow as. Ger3705 ge steam turbine design philosophy and technology.
Steam turbine governing systems and electronic governor retrofit 159 process is required at a specific pressure below the inlet pressure. It is always necessary to check whether lube oil pumps has started and whether all bearings are supplied with oil. The control valve in a steam turbine is a main component included in the turbine set. Pdf investigation on flow characteristics and stability. Full reverse engineering services are also available, including engineered design modifications. The control valves admit steam to the high pressure turbine via four internal nozzle block segments at the center of the turbine rotor. The path taken by steam through the valve inlet, the throat and into the valve outlet is relatively tortuous. This area is manipulated control by position of turbine s control valves. Documented functional testing of your actuator assures a seamless transition to. When firing fuels such as coal, oil, or other waste products. Chapter 7 explains desuperheaters, steam conditioning valves, and turbine bypass systems. In a control valve a great deal more energy is lost to friction than in a nozzle, and, because. It is another interesting method by which turbine s speed can be controlled. The turbine bypass system also enables a combined cycle plant to operate at turndown conditions, below that which can be achieved solely with gtgs.
Adjustment of process steam flow is implemented by the extraction control valve. Industrial steam turbines steam turbines siemens global. The top half has an integrated steam chest, with vertical control valves within the casing. This area is manipulated control by position of turbines control valves. The turbine bypass valves also control steam flow and temperature during turbine and steam generator startup or shut down. Chapter 8 details typical control valve installation and maintenance procedures.
Pdf simulation of speed steam turbine control system. A valve reliability upgrade solution involving the replacement of the valve internal parts only, has been developed for the kanis and abb nuremberg series. Standard offtheshelf field configurable controllers allow users with simple steam turbine applications to easily configure and operate the control themselvesresulting in lowering commissioning and support costs. Chapter 8 offers typical control valve installation and maintenance procedures. The sst800 is a single casing steam turbine with center steam. Control of lube oil pressure and temperature, as well as rotor axial displacement and eccentricity is necessary. The extraction condensing turbine is able to change the electric power and the process steam flow independently by adjusting inlet steam flow and process steam flow. These valves may be part of the turbine casing itself.
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