The steam turbine control valve system with its actuators has to operate at high temperatures at the live steam inlet. Steam enters the turbine with a high energy content and leaves after giving up most of it. The new components are coordinated perfectly to the new electrohydraulic speed control systems with fully integrated electronic overspeed protection for steam turbine types dgdkdegdek. On a steam turbine, a droop proportional only governor produces a change in valve position proportional to the signal between the speed set. 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. The sst600 is a singlecasing steam turbine designed for operation within a speed range of 3,000 to 18,000 rpm for generators or mechanical drives up to 150 mw. An extraction control valve then splits the steam path into an extraction s tream and a low pressure stream. The unit was operated with ramp rates of 30 and 15 seconds in both open valve and closed valve configurations. Speed trip steam turbine control troubleshooting process plant control wiley online library. In the turbine governor the target rotational speed 3000 rpm is set as well as runup rate for instance 75 revmin2. Aeroacoustic analysis of a steam turbine double seat. Control steam with greater efficiency and accuracy. When the steam turbine is under sequence valve control, the valves are opened one by one, so it need to give each valve the proportion and bias factor, to ensure that the valve is.
Dn1400 2 nominal pressure up to pn100 up to pn400 3 max. The steam valve nominal diameters, the steam pressures, and temperatures on these components are many times higher than on the gas turbine. In the turbine bypass station, steam temperature must be reduced to protect downstream components from high temperatures and pressures. The inlet of industrial steam turbines will be controlled by a single valve, or a series of valves multi valve assembly working in concert. Ger3705 ge steam turbine design philosophy and technology.
In case the target speed is set on the value between the turning gear speed and 3000 rpm, one should avoid settings in the range of critical speeds. In a preferred form of the invention, a bypass overload valve is provided in parallel with the steam admission control valves but is connected to discharge steam to a lower pressure stage of the turbine. Valve actual position deviation alarming if position. Steam turbine control valves are generally a high source of noise, as described by araki, et al. The highpressure steam from the boiler is expanded in nozzles to create a highvelocity jet of steam.
The units are designed to replace the previous control valves and actuators. Failure analysis of high pressure turbine control valve. However, few of them produce models with an output of less than 200 kw. When the steam turbine is under single valve control, all the valves are directly controlled by the flow instruction, so proportion and bias factor are not needed. Mechanical drive steam turbines mechanicaldrive steam turbines figure 6 range from 3 to 60 mw 80,000 bhp, with speeds of up to 16,000 rpm, and are either condensing or noncondensing types. Steam turbine control valve and actuation system modeling for dynamics analysis. On all steam turbines there are fast acting steam isolation valves capable of immediately terminating steam supply to the turbine. Aeroacoustic analysis of a steam turbine double seat control. This is achieved by multiple pressure reduction stages and. It is another interesting method by which turbines speed can be controlled. Actuators experience high wear, especially when the steam turbine is situated outdoors. For turbines with chestmounted control valves, it may be a.
In throttlecontrolled turbines, steam to flow is controlled by pressure of steam by the control valves either 2 or 4 to the extent required by load. Additionally, the guide blade carriers enable easy maintainability or further modifications of the steam path. A steam turbine control 16a provides valve position demand setpoints to each of the. Your partner in power industry micro steam turbines, small. Steam turbines are utilized in numerous industries to drive boiler fans, boiler feed and water pumps, process and chiller compressors, blast furnace blowers, paper mill line shafts, sugar mill. 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. Steam turbine inlet valve figure 1 simple steam turbine single extractionadmission turbines in single extraction steam turbines, the steam is admitted through the steam control valve s and flows through the high pressure stages. Steam turbine control troubleshooting process plant control. In a practical situation the load frequently varies from the designed or economic load and thus there always exists a considerable. The turbine is used for both condensing and backpressure applications, either geared or directly coupled. Analysis to determine optimum steam pressure before control. The steam turbine control valve system with its ac tuators has to operate at high temperatures at the livesteam inlet.
Understanding and preventing steam turbine overspeeds by. Hydraulic control systems in gas and steam turbines. Next hp and ip stop valves can be opened, with control valves closed. Temperature c 450 610 4 valve body angle 5 connection weld end flange 6 standard csn, en connection acc. Pdf investigation on flow characteristics and stability of control. Experimental study of steam turbine control valves citeseerx. A method is disclosed for operating a steam turbine using turbine reserve capacity for attaining operation at elevated loads. V ib f vl m u failures, as described by johns, et al. Steam turbines in this size range are of the singlestage type, which implies that turbine efficiency is quite low compared to larger steam turbines or highperformance steam engines. To ansi, gost 7 characteristic linear equal percentage 8 body material cast.
Steam turbines are supplied by several manufacturers. Valve positioning must be accurate for adequate control ofturbine generatorload when syncbronized and speed during runup and syncbronization. Based on the analysis of thermodynamic process in control valve, they deduced a relationship of. Analysis to determine optimum steam pressure before. Elliott multi valve turbines are available for a wide range of applications with horsepower ratings to 5,000 hp 100,000 kw and speeds to 14,000 rpm. The customized steam path is arranged according to the customers needs. Multi valve turbines for higher power applications, elliott multi valve, multistage designs provide the highest levels of efficiency as well as accurate control of speed and steam flow. Advanced steam turbine controls mechanical drives petrotech. The hpc has been specially designed with extra attention to accuracy, response, resolution and is ideal for both inlet and extraction steam turbine control valves relating to turbine speed, load and process control. Steam turbines are utilized in numerous industries to drive boiler fans. What is steam turbine description and characteristics. So, basically steam turbine governing system is a process where turbine maintains a steady output speed irrespective of variation of load.
The boiler turbine unit control schemes have gone through several decades of evolution and, typically, a cascade of pipid controllers based on singleinput singleoutput control loops is designed in the plant to fulfill such tasks. This results in a considerably higher force requirement and thus greater diameters and spring forces of the hydraulic actuators used. Features such as a horizontal casing split or the independently accessible bearings ensure easy and rapid maintenance. Up to four control valves with one or two emergency stop valves poppet or bell valve design no material.
Request pdf flow analysis in a steam turbine control valve with throughflow valve chamber the nuclear power plant also includes a secondary cycle, one of the main components of which is a. Valves for steam and condensate in generating and industrial installations. Steam conditioning valve or turbine bypass systemhp, ip, lp main characteristics of our standard execution the tecpress steam conditioning valve is capable of controlling pressure and temperature simultaneously. The turbine bypass valves also control steam flow and temperature during turbine and steam generator startup or shut down. Products include severe service and general service control valves, variable orifice desuperheaters, raven trim and steam conditioning valves and nuclear control valves, as well as custom designed speciality valves. Steam turbine governor free download as powerpoint presentation. Request pdf experimental study of steam turbine control valves because of the convergingdiverging configuration of the valve passage. Your partner in power industry micro steam turbines. Steam flowing through the high pressure bypass control valve is throttled and cooled to a temperature slightly above the hp turbine exhaust temperature, by spraying feed water at the outlet of the bypass control valve. Overall design approach the design of reliable, efficient steam turbines requires the application of many diverse areas of technology. Directly at the inlet of the steam turbine, there are throttlestop valves and control valves.
Flow analysis in a steam turbine control valve with through. In the event of a turbine trip, the steam supply must be isolated very quickly, usually in the fraction of a second, so the stop valves. Sst800 steam turbine design is in accordance with din or api standards. This valve is the primary means of control steam turbines can also be classified according to the ling the unit. The entire mass flowrate of steam flows through all of the turbine stages. Flow analysis in a steam turbine control valve with. Steam turbine theory use of the hand valves turbine over. Steam turbine control troubleshooting process plant.
Controlling the turbine steam flow with a minimum pressure drop through the control valves is very important. Steam turbine generator overhaul and inspection guidelines. Control valve upgrade solutions for wesel steam turbines fact sheet control valve upgrade solutions for wesel steam turbines 3. Nozzle control governing of steam turbine is basically used for part load condition. Each control valve is operated by a singleacting, springclosed servomotor opened by a high pressure fireresistant fluid supplied through a servo valve.
Steam turbinegenerator overhaul and inspection guidelines. In throttle governing the pressure of steam is reduced at the turbine entry thereby decreasing the availability of energy. The different types of steam turbine governor of are. Development of steam turbine inlet control valve for. Steam turbines can be found in almost any processing plant or power. Asme tdp1 1998 prevention of water damage to steam turbines, part 1 valvtechnologies metalseated valves are designed to meet virtually any process condition.
Fundamentals of inlet control va lves the flow of steam into the steam turbine is regulated by inlet control valve s. The overall internal condition of a steam turbine can be evaluated using the valves wideopen test asme 1985. The primary function of the control valves is to control steam flow to the turbine in response to the turbine control system. Failure analysis of high pressure turbine control valve and. In controlling steam turbine speed, is to accurately and. The turbines or turbine sections are driven by steam, the flow of which is basically controlled by four valve stations, including a main control valve mcv, high pressure bypass valve hpbp, admission control valve acv, and a low pressure bypass valve lpbp. Their accuracy and reliability are important for maintaining the highest turbine output, and maximum megawatt hours to the grid. Control valves control valves 1 nominal size dn100.
Pdf throughflow capability and flow stability of some steam turbine control valves were studied by experimental investigation and numerical. Steam power plant configuration, design, and control. Chapter 6 addresses the selection and use of special control valves. Smallmidsized steam turbines are designed based on a modular design md concept in which standardized modules for turbine components, such as governing valve chests and low pressure exhaust casings are employed. The steam turbine is a device for obtaining mechanical work from the energy stored in steam. An extraction control valve then splits the steam path into an extraction stream and a low pressure stream. Chapter 7 explains desuperheaters, steam conditioning valves, and turbine bypass systems.
Maintenance and overhaul of steam turbines wgp42 05. Ger3706d steam turbines for industrial applications. Describe the generation of turbine valve positioning signals in the following components of the electrical control system. Venturi valves are widely used in modern large turbines as turbine governor valves to regulate the ow entering the turbine. The drive for improved reliability and availability resulted in the industry backing away from both the 1050f steam temper atures which were common in the late 50s and early 60s and the 3500 psig supercritical throttle. These main steam valves permit steam entry into the high pressure hp turbine. Pdf study on valve management of deh for steam turbine. Us4403476a method for operating a steam turbine with an. In the event of a turbine trip, the steam supply must be isolated very quickly, usually in the fraction of a second, so the stop valves must operate quickly and reliably. Our standard class valves are available from 38 36 inches, up to asmeansi class 4500.
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. Depending on the users ability to handle the maintenance for complex systems. Typical design heat balance diagrams values of main steam pressure before control valves at 100% load, 80% load, 65% load, and 50% load in constant pressure mode and sliding pressure mode is shown in table i. The control valve is designed to close in approximately 0.
Experimental study of steam turbine control valves request pdf. Due to an intricate pressure reducing arrangement the steam pressure is reduced subcritical at all load levels. Typically, the high noise occurs mostly at high pressure drop, with or without shock. The stop and control valves close in approximately 0. 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. Turbine control is achieved by varying these turbine valves openings. A simple example of control is manual control of a steam valve to regulate the temperature of water flowing through a pipeline fig. Replacement of the nut, distance sleeve and, if existing, disc spring with an integrated collar with proper axial clearances between the lifting bar and the collar. These tests do not require a test measurement of steam flow, which reduces the complexity and hence cost. Each control valve is operated by a single acting, springclosed servomotor opened by a high pressure fireresistant fluid supplied through a servo valve.
Feedback valve actuator control relay governor steam valve steam valve actuation figure 3. Highpressure turbine the hp turbine receives steam through four steam leads, one from each control valve outlet. The variation in load during the operation of a steam turbine can have a significant impact on its performance. Jul 14, 2008 summary this chapter contains sections titled. This flow is then combined with high pressure exhaust steam and passes through the reheater. Using an integrated approach in production process includes customer support in engineering projects and wide range of services, in particular. Approval issue module 2347 the turbine governing system. The turbine control valve steam flow shutoff rate, upon a step reduction to zero in pressure regulation flow demand no resulting bypass steam flow demand, will.
312 640 1117 1178 1717 411 1313 766 1551 660 84 178 1622 1023 171 182 1369 772 810 1266 209 1207 1418 743 1358 1342 1377 1684 1032 1798 33 366 1270 663 1003 790