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. A great influence on blade life, however, has the designer with the choice of mechanical and steam loading per blade, selection of shroud and root configuration for specific location. Newtons third law for every action there is an equal and opposite reaction. Participants will build their understanding using two rotor, four bearing simple setup and finally address issues that come up with multiple rotor systems, 3. The steam turbine rotors must be designed with the most care as it is mostly the highly stressed component in the turbine. Governor systems are speedsensitive control systems that are integral with the steam turbine. In addition, the rotor diameter, height of the first and last blades, the number of stages and the thermodynamic cycle of system are also used to determine the design conditions. There the kinetic energy and thus the absolute velocity of the steam is again reduced in order to produce a rotational force. In the complex systems, many of the engineering problems, it is. One the threshold is exceeded, automatic trip of turbine takes place. Pdf design optimization and analysis of a steam turbine rotor. Research paper design modification for fillet stresses in.
C61207 this standard specifies the minimum requirements for steam turbines for specialpurpose applications for use in the petroleum, petrochemical, and natural gas industries. Ashutosh vengurlekar exxonmobil research and engineering, singapore. Doubleflow, lowpressure rotor with 42inch 1067 mm laststage buckets. The impulse turbine, in which the pressure drops across the stationary blades. The steam turbines are widely used in power generation, refineries and petrochemical industries. Steam turbines lie at the heart of these power plants. 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. 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. Unesco eolss sample chapters thermal power plants steam turbine components and systems r. Modern ge steam turbines for electrical power generation are the result.
The rotor is turned by steam impinging against attached vanes or blades on which it exerts a force in the tangential direction. Description the perfect modernization solution for your steam turbine given the relatively low fuel cost of coal and nuclearpowered steam turbine generators, and the increasing strategic value of existing sites, a modernization of existing equipment can be more costeffective and faster than installing new generation equipment. Elliott steam turbines are rated for inlet steam conditions up to 2000 psig1005 degrees f and speeds up to 20,000 rpm. Differential expansion of steam turbine generators by chris james skf reliability systems turbine supervisory instrumentation. Axis wind turbine rotor and comparison with simulations from two blade element momentum codes, elsevier journal of wind engineering and,20 6 ronit k. Steam turbines startups 1 principles of steam turbines startups. The interaction between mechanical and electrical system and the fact that the structural damping of the torsional modes is low are the main reasons for most of the root causes leading to torsional vibration problems. Low cycle fatigue lcf, transient, thermal strain, steam turbine rotor 1. The low pressure impulse steam turbine blade rows have a history of stress failure. 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 rotor shaft of a steam turbine is a very important. Lprimlife for rotors with bladeattachment cracking suitable for use with all rotor designs, lprimlife developed on behalf of epri, is a software code to assess the life of steam turbine rotors with bladeattachment cracking. To allow unrestricted growth of the turbine rotor assembly, the machine rotor is restricted from axial movement within the machine case at one fixed point and allowed to.
Rafiuddin ahmed, blade design and performance testing of a small wind turbine rotor for low wind speed applications, elsevier renewable energy,20. The rotor is the core component of a gas turbine, and more than 80% of the failures in gas turbines occur in the rotor system, especially during the startup period. The low pressure steam turbine rotor blades have usually a history of stress failure. Overspeed the turbine to check the overspeed trip visually inspect the turbine generator string for.
For low and moderate inlet steam pressure up to 120 bar, a single shell. Steam turbine basic parts mechanical engineering site. Steam turbine rotor is applied to determine stress concentration factors. 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. Journal and thrust bearing for compressor and turbine duration. The casing shape and construction details depend on whether it is a high pressure hp or low pressure lp casings. Prior to startups turbine rotors must be thermally stabilised, and their deflection line must coincide with the gravity deflection line. A 230 mw steam turbine exhibited gradual deterioration of dynamic behavior shortly after commissioning. The generator rotor is magnetized, and its rotation generates the electrical power in the generator stator. There is no piston rod,flywheel or slide valves attached to the turbine. A lowpressure steam turbine rotor for mw class power plants becomes a large rotor of more than 500 ton in its ingot weight.
The real values of critical speeds should be measured at. Turbine stages, comprising nozzlestator and rotor blade rows. Low cycle thermal fatigue damage in steam turbine rotor. Us6499946b1 steam turbine rotor and manufacturing method. What is steam turbine description and characteristics. A steam turbine rotor having a combination of at least one of a high pressure rotor, an intermediate pressure rotor and a low pressure rotor, which are each formed from a metal material of different chemical composition and welded together by means of welding. Turbine rotors are classified as a disktype rotor and a drum type rotor from the viewpoint of configuration. These requirements include basic design, materials. When building saturated steam turbines for nuclear power plants with an output of. Th e tsr is the amount of steam fl ow needed to drive the turbine at the specifi ed steam conditions, assuming that the turbine is 100% effi cient. One of the fi rst steps in selecting a steam turbine is calculating the eoretical steam rateth tsr.
Consists of springopposed rotating weights, a steam valve, and an interconnecting linkage or servo motor system. Chaplin encyclopedia of life support systems eolss both of these have double casings with the exhaust steam circulating in the annular space between the casings as in the case of the high pressure turbine. Optimized approach for determination of the solid temperature in a. In its simplest form, a steam turbine consist of a boiler steam generator, turbine, condenser, feed pump and a variety of auxiliary devices. Differential expansion rotor long when high temperature steam is applied to the machine as during a machine startup, the rotor thermally expands at a faster rate than. A typical large steam turbine power generation unit will have a thick case, on the order of 12 to 18. Turbine stop valve opened slowly until the rotor speed between 300 400 rpm. A steam turbine is a mechanical device that converts thermal energy in pressurized steam into. The aim of balancing is to reduce the amplitude of vibration to a tolerable level, which can be. Steam turbine is a heat engine that converts heat energy of the high temperature and pressure steam to.
Four different types of rotor construction have been used on large turbinegenerator units on the cegb system. From there, steam flows through second stage of stator blades or guide blades where steam is proceeded to the second row of moving or rotor blades. The blades in turn change the direction of flow of the steam however its. Steam turbine working principle and types of steam turbine. Residual life assessment of 60 mw steam turbine rotor. To allow unrestricted growth of the turbine rotor assembly, the machine rotor is restricted from axial movement within the machine case at one fixed point and allowed to move from that point.
The steam turbine is, ironically, the most ancient form of steam engine and many inventors, including trevithick, have experimented with the concept, but it was not until the 1880s that the british engineer charles parsons succeeded in designing a practical engine. Nevertheless modern steam turbines are very efficient and operate with internal efficiencies within the range of 80 percent to 90 percent depending upon the steam conditions. Due to the mass of this case, it will expand and contract at a slower rate than the relatively thin hollow rotor. In his design, high pressure steam expanded through a cylindrical housing so that it pressed against a series of. Rotor bending that results in premature failure of steam turbine blades and other internal components is one of the most serious problems experienced in power plant operations. Above 600 rpm rotor relative vibrations should be monitored. Constant circumferential section heat insulated disc rotor. In this article, we will discuss steam turbine basic parts. Unit iii unit iii steam nozzles and turbines flow of steam through nozzles, shapes of nozzles, effect of friction, critical pressure.
A steam turbine consists of a rotor resting on bearings and enclosed in a cylindrical casing. Especially the temperature of the rotor is a determining factor which is not measured in commercially operated. Failure analysis of a steam turbine rotor engineering failure analysis, 2011. A bearing portion rotor 1 and high temperature portion rotor 2 are jointed at weld portion a, the high temperature portion rotor 2 and low temperature portion. Thus a steam turbine could be viewed as a complex series of windmilllike arrangements, all assembled on the same shaft. Rotor is an very important part in the machines, especially in the rotating machines like gas and steam turbines. Shrink connection modelling of the steam turbine rotor.
A steam turbine different material welded rotor, constructed by rotors of different materials being jointed together by welding has the strength of a jointed portion increased and inspection of the jointed portion facilitated. Tensile strength and ductility at lower temperatures. With power requirements, steam conditions, and speeds constantly rising, elliott has continued to develop its steam turbine product lines to meet ever more challenging operating conditions. A steam turbine is a mechanical device that extracts thermal energy from pressurized steam and transforms it into mechanical work. Residual life assessment of 60 mw steam turbine rotor k. Toshiba 600 mw steam turbine rotor installation duration. It consists of a rotor and a set of rotating blades which are attached to a shaft. Through optimal application of technology and proven expertise, stork turbo blading is unmatched in. However, as 100% effi ciency is not possible it is referred to as the th eoretical steam rate. The monobloc or integral rotor, in which the wheels and shaft are formed from a singlepiece forging fig 1.
Efficiency will depend on turbine size or rotor diameter, blade geometries, speed, extreme condition of steam and other losses. They suffer from tensile and bending stresses partly due to the centrifugal force. Us6152697a steam turbine different material welded rotor. The highpressure rotor of a large turbine as shown in fig. Geometric discontinuities cause a large variation of stress locally, and often produce a significant increase in stress called as stress concentration. If the hand wheel is turned too quickly the oil valve will be lifted off its seat in the oil power piston, thereby destroying the oil pressure and allowing the valve to close under the action of steam pressure. Bievenue ge company schenectady, new york introduction ge turbine designs have evolved over a period of some 90 years, during which over 3,000 units were produced, with the objective of achieving the best.
Steam consumption of steam turbine is depending to required output power and efficiency of the turbine. This can also appear when loads are applied over a small area or at a point. Because the turbine generates rotary motion, it is particularly suited to driving electrical generators about 90% of all electricity generation in the united states 1996 is by use of steam turbines 1 wiser. Ger3646d steam turbines for large power applications. The work produced by a turbine can be used for generating electrical power when combined with a generator. The turbine speed is controlled by varying the steam flow through the turbine by positioning the governor valve. Teeslots are machined circumferentially in the periphery of the rotor front and rear halfcoupling flanges to permit the weights to be positioned and retained. Introduction nonavailability of various components of thermal power plants leads to loss of generation. The steam turbine is one kind of heat engine machine in which steam s heat energy is converted to mechanical work. Unlike with reciprocating engines, for instance, compression, heating and. The design of a turbine rotor depends on the operating principle of the turbine.
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