The extremely large casing sizes and extremely high steam temperatures of turbines used in electric power generation service can easily result in up to two inches 50 mm of axial growth. Each time it starts, the turbine after rolling about 2 or 3 hours differential expansion reach to its limit 1mm, and turbine trips, we have scyncronizing and reaching to 20mw during this 3 houres. Parsons main thrust for the steam turbine was for generating electrical power, but he also had his eyes on applying the steam turbine to drive ships of all kinds. This turbine is called rmaple impulse turbine since the expansion of the steam takes place in one set of the nozzles. High pressure steam is admitted slowly into a turbine to warm it up and remove condensate moisture produced by condensation. Thermal power plant based on a rankine cycle in a simple rankine cycle, steam is used as the working fluid, generated from saturated liquid water feedwater. Taking into consideration thermal expansion and dilatation measured from photogrammetry it is observed that the turbine generator gets misaligned when the steam turbine gets hot figure 6. 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. The first steam turbine used for power generation was invented in 1884. This article focuses on marine steam turbines and their applications. The current w501d model represents a power enhancement over the earlier westinghouse 70 mw units which have been in service for many years. Steam turbines are used to drive the electric generators in modern power plants. Nov 30, 2017 steam is expanded from 90 bar, 412c to 4.
A water seal is shown in figure 1, page 8, and consists of a. What is differential casing expansion in steam turbine. To maximize turbine efficiency the steam is expanded, doing work, in a number. What links here related changes upload file special pages permanent link. W501d gas turbinegenerator system currently used in a number of utilities. Steam does not condense at the saturation temperature corresponding to the pressure. Both the ends are supported on independent pedestals. Hp part consists of two horizontally split casingsinner is placed inside, outer casing with scope for expansion in all direction. The results of the numerical simulations the computation has been done by using the method of characteristics and method of finite differences. Notes references module 2348 the turbine supervisory system. In some stations, lp turbine exhaust hood temperatures. The pressurized steam is expanded to lower pressure in a turbine, then exhausted either to a condenser at vacuum conditions, or into an intermediate temperature.
Extraction steam turbines are frequently used in cogeneration as well as industrial power plants. During the design of a steam turbine, limiting dif ferential expansion is calculated relative to the thrust bearing position and clearance is then pro vided to assure. Dynamic analysis and field balancing of 100 mw utility gas. Steam turbine technology kth royal institute of technology web.
Turbine is a rotary engine that converts the energy of a moving stream of water, steam, or gas into mechanical energy. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency through the use of multiple stages in the expansion of the steam, which results in a closer approach to the ideal reversible process. Nonlinear mathematical model of the condensing steam turbine 875 where. Isentropic expansion within a steam turbine system physics. As the steam flows through the nozzle its prenzsure fall. Steam conditions the turbine expansion line or condition curve represents steam conditions prevailing in sequential stages of the steam turbine. A typical large steam turbine power generation unit will have a thick case, on the order of 12 to 18. Jun 24, 2015 in the second part of this series, the author talked about the story of the first little toy turbine. Research paper on study of steam turbine amanraj dronacharya college of engineering, gurgaon123506, india abstract. Velocity diagram of simple impulse turbine, various performance parameters. To fix the extraction pressure level, it is necessary to control the low pressure turbine downstream of the steam extraction point. Process of complete expansion of steam takes place in stationary nozzle and the velocity energy is. Reaction turbine blading and conditions figure 3 shows, at the top.
Rotor expansion on a turbine is the absolute measurement of the rotors axial thermal growth with respect to the turbine s foundation. A steam turbine is a mechanical device that extracts thermal energy from pressurized steam and transforms it into mechanical work. Unesco eolss sample chapters thermal power plants vol. The remaining steam is then expanded through a low pressure turbine to 1. Despite efforts to develop alternative energy converters, electricity from steam will continue, for many years, to provide the power that energizes the united states and world economies. Generally in a steam turbine the rear support of the steam turbine or the rear side of the casing is fixed. In the second part of this series, the author talked about the story of the first little toy turbine. As seen in figure 5, the turbine generator was aligned in cold condition. Although the application of differential expansion and rotor expansion have much in common, it is important to understand the difference between the two measurements.
As aminimum, these are the hp and lp turbine inlet steam and metal temperatures. The primary purpose of a differential expansion monitor is to guard against axial rub between rotating and stationary parts. Rotor expansion on a turbine is the absolute measurement of the rotors axial thermal growth with respect to the turbines foundation. About the presentation this presentation teaches the reader about the operation and importance of steam turbines in electricity generation. Differential expansion monitoring measures the change in axial clearances between the machine rotor and casing caused by thermal changes inherent in most machines.
Differential expansion of the steam turbine cr4 discussion. Steam turbines classification, governing equations and. A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to. 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. Two casing, doubleflow steam turbine with shellmounted valves. Turbines in ohio, kentucky and indiana lathrop trotter. In its simplest form, a steam turbine consist of a boiler steam generator, turbine, condenser, feed pump and a variety of auxiliary devices. Likewise, it undergoes contraction as its case cools during steam reduction. Steam leaves the fixed blades of one stage of a reaction turbine at 122 ms with an exit angle of 23. Lathrop trotter is the source for gas and steam turbines, turbine generator sets, and combined heat and power solutions. Steam from the boiler is expanded in the nozzle blade passages to produce high. Following figures show steam process in steam turbine. The computeraided design cad files and all associated content posted to this website are created, uploaded, managed and owned by third party users. The moving blades travel with a linear speed of 88 ms and the steam consumption of the turbine is 1.
Thermalengineeringbyrkrajput chapter19 steam turbine. Isentropic expansion expansion in a steam turbine steam from the boiler expands adiabatically from state 3 to state 4 in a steam turbine to produce work and then is discharged to the condenser partially condensed. 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. Excellent text on steam turbine design but now dated as it covers only smaller units. Differential expansion sensitivity studies during steam. Dec 19, 2014 velocity diagram of simple impulse turbine, various performance parameters. The gas turbine is a steady flow device in which air is compressed to a high pressure in the compressor, fuel is added in the combustion chamber, resulting in a high temperature at the turbine inlet. Pdf power plant lecture notes chapter4 steam turbine. Steam turbine fundamentals an introductory guide to the operation of modern steam turbines v. Ger3646d steam turbines for large power applications. In case of turbines with cooling water preheating and lowpressure lp bypass, prior to supplying steam the regeneration and dumping systems have to be.
Approach to high efficiency diesel and gas engines pdf. Plotted on a mollier diagram it provides a useful visual image of these conditions. Each cad and any associated text, image or data is in no way sponsored by or affiliated with any company, organization or realworld item, product, or good it may purport to portray. Steamturbine principles and practice by croft, terrell, 1880publication date 1923 topics steamturbines. The turbine consists of three casings, high, medium and low pressure. When turbine is in service, superheated steam temperature above 540 degree celsius is admitted into the turbine.
Steam turbine generator shaft grounding principles historically, the problems and solutions to electrostatic and magnetically induced voltages on the steam turbine generator shafts of the test utilitys steam electric stations have been a continuous one. Isentropic expansion within a steam turbine system. Turbine supervisory instrumentation system tsi on large steam turbine generator applications. Arabelle uses more efficient single flow steam expansion. The utility gas turbines present a number of challenges as compared to conventional steam turbines. Steam process in steam turbine steam entrance to turbine through governor valv e to control steam capacity and therefore to control turbine speed. Chaplin encyclopedia of life support systems eolss figure 4. An analysis of a thermal power plant working on a rankine. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The steam does work on the surroundings blades of the turbine and loses an amount of enthalpy equal to the work that.
Steam turbines are one of the most versatile and oldest prime mover technologies still in general production used to drive a generator or mechanical machinery. Differential expansion on a turbine is the relative. Steam turbines startups 1 principles of steam turbines startups. Figure 3 supersaturated expansion of steam into wet region 3. We are commissioning this turbine for the first time. A multistage steam turbine is considered to be one of the worlds most powerful engines. In a steam turbine, highpressure steam from the boiler expands in a set of stationary blades or vanes or nozzles. Consider steam turbine drives for rotating equipment steam turbines are well suited as prime movers for driving boiler feedwater pumps, forced or induceddraft fans, blowers, air compressors, and other rotating equipment. Modern ge steam turbines for electrical power generation are the result of.
Sensonics technical note ds1220 differential expansion measurements on large steam turbines one of the challenges facing instrumentation engineers in the power generation sector is the accurate measurement of shaft growth relative to casing on large steam turbines. Turbine stages, comprising nozzlestator and rotor blade rows. This saturated steam flows through the turbine, where its internal energy is converted into mechanical work to run an electricity. Unlike with reciprocating engines, for instance, compression, heating and expansion are continuous and. The highpressure turbines are modelled for a design situation and for partload situations with 80% and 40% of the power at design situation. Impulse steam turbineimpulse steam turbine on impulse turbine a thermal expansion take place only in theon impulse turbine a thermal expansion take place only in the nozzles and static energy is converted to the kinetic energynozzles and static energy is converted to the kinetic energy there is no pressure different at inlet and outlet of.
This provides a follow up of basic engineering cycles with applications to conventional power plants. There are two classical types of turbine stage designs. We work to assess and address specific application needs so we can specify and develop a turbine system package that meets and exceeds goals. Differential expansion sensitivity studies during steam turbine startup article in journal of engineering for gas turbines and power 86 september 2015 with 385 reads how we measure reads. See more ideas about steam turbine, abandoned factory and industrial photography. W501d gas turbine generator system currently used in a number of utilities. Figure 4 shows steam process in enthalpy against entropy diagram of curtis and single row rateau turbine. All steam entering the feed pumps shall be a saturated fluid. High velocity steam hits the moving blades converting the kinetic energy into mechanical work. Page 522 end of chapter answer guide 2nd class b1 10. In this kind of turbines, large amounts of steam are extracted at an intermediate pressure level. Prior to supplying steam to the turbine, the steam supply pipelines have to be drained and heated up.
A steam turbine undergoes thermal expansion as its case heats during steam admission. Fluid dynamic investigation of an alternative extraction. Elec0047 power system dynamics, control and stability. This service generally calls for a backpressure noncondensing steam turbine. Mathematical model for digital simulation of steam turbine set dynamics and online turbine load distribution institute of heat engineering, warsaw university of technology, nowowiejska 25, 00665 warsaw, poland abstract the general structure and purposes of. Dec 10, 2015 this turbine is called rmaple impulse turbine since the expansion of the steam takes place in one set of the nozzles. The basic element in a turbine is a wheel or rotor with addles, propellers, blades, or buckets arranged on its circumference in. In noncondensing turbines or backpressure turbines, steam exhausts at a pressure greater than. Consider steam turbine drives for rotating equipment. It includes heat exchange and energy conversion equipment. Earlier steam turbine generating units had an inherent grounding.
To fix the extraction pressure level, it is necessary to control the low pressure turbine downstream of. The expansion process provides significantly more power than is. This measurement is typically performed on larger steam. Free kindle book and epub digitized and proofread by project gutenberg. Steam turbine casing front side is generally free and slide on the front side bearing pedestal. Mathematical model for digital simulation of steam turbine.
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