How steam turbine protection system works turbomachinery. In water turbines, governors have been used since the mid19th century to control. A turbine governor is provided for this arrangement. To limit the speed rise to an acceptable limit upon a load rejection when the unit is suddenly disconnected from the load to control the power that is generated by controlling the position of the steam governing valve or fuel valve in gas turbines to control the speed of the turbogenerator during initial runup and. Two or more steam turbine choices are available for each stag system. Approval issue course 234 turbine and auxiliaries module 10 stressed that these consequences. 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. A control valve is used to control the direction of oil flow. This plant encompasses more than a century of experience in steam turbine technology. The schematic representation of hydraulic governor control is shown in. There have been numerous causes of steam turbine failures worldwide.
However in later steam turbine control hydraulic governor is provided in parley with the electrohydraulic governing as a back up control which readily assumes the turbine control in the event of ehc failure. Along with providing lubrication to the shaft bearings, the lubricant also lubricates the oil pump, and in some systems is used as a turbine control fluid in the hydraulic governing system. The modern digital turbine control system tcs is designed to control the main steam flow to the steam turbine in all operational conditions by means of the turbine throttle, governor, admission. These requirements include basic design, materials, fabrication, inspection testing, and preparation for shipment.
Chapter6 hydroturbine governing system iit roorkee. Steam turbine governing system is a method, used to maintain a constant steady speed of turbine. The steam turbine training course has been developed to assist in turbine maintenance and turbine operation. Steam turbine training and governing system training. Approval issue module 2347 the turbine governing system.
H02p 904 7 claims abstract of the disclosure a speed governing system for a steam turbine comprises a governor valve for. The electronic governor may also improve plant production from driven equipment through enhanced steam management while providing realtime data on. In the few candu units wh turbine lubricating oil, instead of frf, is used in. The importance of fluid health is never more apparent than on an electrohydraulic control ehc system that is responsible for the critical task of governing steam delivery to turbines that drive electric generators in a power plant. Steam turbines startups 171 prior to switching on the turning gear, oil system is started up. The turbine will not start unless the control oil pressure has been substantiated, and as most interlocks or shutdowns use it to dump the oil pressure and thence shut the throttle valve, its a v.
Steam turbine control valve and actuation system modeling. The major concern caused by too high pressure oflubricating orjack ing oil is that it,increases the risk of system overpressure failure if the reliefvalves failed to operate. Steam turbine governing systems and electronic governor retrofit 159 process is required at a specific pressure below the inlet pressure. When the turbine is running at a normal speed of 3000rpm, then the desired quantity of oil to the governing systems and the lubrication systems is supplied by this pump. Unesco eolss sample chapters thermal power plants vol. While selecting a steam turbine as a driver for compressors or pumps for refinerypetrochemical industries. The steam turbine is controlled by the governor, which can be. Maintenance and overhaul of steam turbines wgp42 05. Simulation of speed steam turbine control system sciencedirect. Turbine governing steam turbines free download as pdf file. Throttle governing throttle governing big turbines in larger steam turbines an oil operated servo. It covers the governing system and includes working of the woodward governor type. Turbine governing steam turbines machines vacuum scribd.
The function of the steam turbine protection system is often confused with the control system, but in fact the two systems are entirely separate. Depending on the type of installation, this also may include the hydraulic control system, oil. Speed governing systems for steam turbines filed aug. What is the purpose of a control oil system in a turbine. Main steam also provides turbine throttle pressure indication which is the major control parameter for the ehc system. Figure 9 incorporates an electric governor for a multivalve unit also utilizing a full oil relay system. The above picture is just a screen shot, click to see demo. Governing system or governor is the main controller of the hydraulic turbine. Pdf simulation of speed steam turbine control system. Units with different steam turbines for stag combinedcycle power systems m. The steam turbine working principle and theory has been explained in. An electronic governor can provide precise speed control with fewer wearing parts than an equivalent mechanical governor. Steam turbine training governing system training course.
General electric systems technology manual chapter 3. It is coupled to the turbine rotor through a gear coupling. Power plant steam turbine auxiliaries play the same role, and are best described by systems such as steam system superheated expanding through the turbine, exiting as low pressure steam to the condenser. Historically, these systems employed mineral oil based fluids. In an extracting type turbine, steam is released from variousin an extracting type turbine, steam is released from various stages of the turbine, and used for industrial process needs or sentstages of the turbine, and used for industrial process needs or sent to boiler feed water heater to. Steam turbine governing is the procedure of controlling the flow rate of steam to a steam turbine. Claire soares, in gas turbines second edition, 2015. Industrial steam turbines baker hughes, a ge company. Turbine systems are subject to contamination from several sources and deposits will accumulate even though the oil is clean. 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. In this system, a centrifugal governor is driven from the main shaft of turbine by belt or gear arrangement. Modern steam turbines are of two types, reaction and impulse having numerous mechanical arrangements to drive the generators meeting the ever increasing electrical power consumption. The type of hydraulic actuator that is most commonly used today. The first question faced by the design engineer is which standard steam turbine as to be selected either api 611 or api 612.
Figure 1 is a simple illustration of the general components and travel route of turbine oil in a steam turbine lubrication system. 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. To act as the shutdown and speed control mechanism. Pdf steam turbine control systems are being designed with todays technology to operate a. Us3427464a speed governing systems for steam turbines. 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. There are many considerations to be taken when choosing a controller. In steam turbines, the 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.
The various turbine types have been explained in detail. Pressure oil system with oil servomotor is most commonly used actuator. Steam turbine control valve, governing and lube oil system. Introduction in steam turbine st control and actuation, the steam control valve plays a key role in two main areas. Chaplin encyclopedia of life support systems eolss the flow of high pressure steam entering the turbine is controlled by governor valves and stop valves.
The former control the flow to ensure that the appropriate amount of. General industrial steam turbine prefers a steam source of 42 kgcm2 600 psi at 482 oc 900 o f. A typical turbine governing system has two unloaders one activated by low condenservacuum. In larger steam turbines an oil operated servo mechanism is used in order to. Operation of the typical hydraulic actuator of a turbine steam valve and purity of the. Identification of model parameters of steam turbine and governor. Ger3582e steam turbines for stag combinedcycle power. The purpose of the governor is to supply steam into the turbine in such a. It also covers the related lube oil systems, instrumentation, control systems, and auxiliary equipment. Turbine governing the steam flow through the control valve is.
Managing the health of fire resistant steam turbine. To control the power generation through precise control of steam governing valve. Overview the four main functions of the governing system1 are as follows. Simulation of speed steam turbine control system cyberleninka. A steam turbine oil s most important functions are to. The importance of this method is, the turbine can maintain a constant steady speed irrespective of variation of its load. Steam turbine control systems are being designed with todays technology to operate a turbine in a safe and reliable manner. Theacti vatedunloader acts similarly to the loadlimiter, ie. It is always necessary to check whether lube oil pumps has started and whether all bearings are supplied with oil. Turbine lube oil system flushing and initial filtration should be addressed when selecting turbine oil. To limit the overspeeding speed rise upto acceptable limit upon load rejection. Steam turbine control valve and actuation system modeling for.
580 716 249 1360 1213 1014 275 1136 740 958 1178 1392 1103 1160 1455 914 1066 1315 399 986 109 1272 117 1090 349 46 559 428 1191 242 225 29 135 1325