Another critical aspect of turbine operation is governing to maintain speed and load. The inner turbine is axially split, which is accommodate thermal expansion. Hence for the continuous and uninterrupted power generation the turbine inspection, particularly the blade inspection becomes very important in a power plant. Steam turbines classification, governing equations and. Introduction to turbine machinery university of ljubljana. In an impulse turbine the blades are symmetrical about the plane of the turbine wheel carrying the blades whereas in a reaction turbine they are not. One the threshold is exceeded, automatic trip of turbine takes place. In the turbine machinery the energy conversion is indirect and always takes place through the change of kinetic energy of the fluid. Key aspects related to plant control are addressed. Consider installing highpressure boilers with backpressure turbinegenerators when specifying a new boiler, consider a highpressure boiler with a backpressure steam turbinegenerator placed between the boiler and the steam distribution network. Generally in a steam turbine the rear support of the steam turbine or the rear side of the casing is fixed. The thrust bearing is placed at the inlet end of the turbine casing as this is the hottest end and hence the most effected by differential turbinecasing expansion. And finally the third part is practical one, in it the start point is a rankine cycle used in a plant working at nominal load.
Then the both, nozzle and throttle governing are calculated with two different mass flow than nominal flow. A turboexpander, also referred to as a turboexpander or an expansion turbine, is a centrifugal or axialflow turbine, through which a highpressure gas is expanded to produce work that is often used to drive a compressor or generator. The steam turbine thermal transient model st3m tool developed at kth. Consider installing highpressure boilers with backpressure.
The supplier decided to make good and to re design some parts of the turbine. Comparing combined gas tubrinesteam turbine and marine low speed piston enginesteam turbine systems in naval applications abstract the article compares combined systems in naval applications. For example, after a weight has been placed at the hot end of the gas turbine, it usually takes a day for the system to cool down before another balance weight may be applied at that location. Hp turbine the outer casing of turbine is of barrel type, which has neither axial nor a radial flange. The principles of correct conducting startups have been developed over the longterm operation of steam turbines and contain experience of turbine designers, constructors and operators. Three basic phases can be distinguished in the process of steam turbine unit start. Differentialrotor expansion sti vibration monitoring inc. 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. An ideal steam turbine is considered to be an isentropic process or constant entropy process, in which the.
Thermal expansion of the shaft would be in an axial direction away from the. It is particularly embarrassing if a balance weight should be dropped into the gas turbine. The object of the analysis is the combined gas turbinesteam turbine system which is compared to the combined marine lowspeed diesel enginesteam. Reaction turbine 2 iii steam turbine operating range 2 3. In the turbine the fluid flows from the pressure penstock into the turbine machine and first flows through a. Initially the pressure is high representing a high energy level. Larger turbines require controlled thermal transients as the massive casing heats up slowly and differential expansion of the parts must be minimized. Lower pressure ratios across each stage results in twice as many stages for given energy range. The difference between the two is easily seen when viewing the blades from the end. Aug 23, 2014 hp turbine the outer casing of turbine is of barrel type, which has neither axial nor a radial flange. Data sheets pdf, newsletter archive, certificationsdocuments.
This helps to prevent damage to the glands and also allows the use of reduced clearances, necessary as the specific volume of the steam is at its highest. Jan 02, 2009 free kindle book and epub digitized and proofread by project gutenberg. Since the energy in the steam is represented by the pressure heat energy and velocity kinetic energy, the conversion and transfer of energy in the blading can be visualized. Steam turbine differential expansion amp maintenance forums. The primary purpose of a differential expansion monitor is to guard against axial rub between rotating and stationary parts. Differential expansion on a turbine is the relative. 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. Comparing combined gas tubrinesteam turbine and marine low. Above 600 rpm rotor relative vibrations should be monitored. Anchor point is always located near high temperature end to minimize the differential expansion. 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.
Ip turbine the ip turbine is a dual flow turbine, with horizontally split casings. Although the application of differential expansion and rotor. 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. The first steam turbine used for power generation was invented in 1884. This measurement is typically performed on larger steam. The turbine is a vital component in a power station. Consider installing high pressure boilers with backpressure turbinegenerators when specifying a new boiler, consider a highpressure boiler with a backpressure steam turbine generator placed between the boiler and the steam distribution network. Chaplin encyclopedia of life support systems eolss figure 3 supersaturated expansion of steam into wet region 3. In order to assemble the turbine and to disassemble it for maintenance, the casing must be split in some way. Toshiba has delivered four sets of 1100 mwe steam turbines, generators, and main heat exchanger systems as planned for the aptm, westinghouse electric company llcs latest pressurized water reactor pwr under construction in the united states. 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.
Figure 5 and figure 6 clarify the concept of flow areas and blade symmetry. Steam turbines are used to drive the electric generators in modern power plants. Design and analysis of hp steam turbine casing for. Dynamic analysis and field balancing of 100 mw utility gas. Comparing combined gas tubrinesteam turbine and marine. Approval issue course 234 turbine md auxiliaries module 14 thermal expansion or settlingcracking of the concrete founda tion. The following addresses best practices for optimal steam system turbine maintenance and operation. The output power of the turbine at steady flow condition is.
A turboexpander, also referred to as a turboexpander or an expansion turbine, is a centrifugal or axialflow turbine, through which a highpressure gas is expanded to produce work that is often used to drive a compressor or generator because work is extracted from the expanding highpressure gas, the expansion is approximated by an isentropic process i. Steam quality steam must be of the highest quality. Pdf portable document format pdf 68 care and maintenance. Validating and modeling of steam turbine temperature distribution. This chapter deals with the operating concepts of a candu nuclear power plant. 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. Differential expansion on a turbine is the relative measurement of the rotors axial thermal growth with respect to. Steam turbines startups 1 principles of steam turbines startups. Because the turbine generates rotary motion, it is particularly suited to be used to drive an.
Simplified physical understanding of gas turbine matching in a gas turbine engine, the operating point is defined by the match between the compressor and the turbine. Best practices for steam turbine maintenance and operation. Differential expansion of the steam turbine cr4 discussion. Although the application of differential expansion and rotor expansion have much in common, it is important to understand the difference between the two measurements. Steam turbine casing front side is generally free and slide on the front side bearing pedestal. 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. Keywords steam turbines, transients, startup, finite element model, heat transfer. Gas turbine balancing runs can be extremely timeconsuming. Differential expansion on a turbine is the relative measurement of the rotors axial thermal growth with respect to the case. The above picture is an example of two simplified inlet data files but shows an. Aging ofthe equipment maycause settling and cracking ofthe foundation. Free kindle book and epub digitized and proofread by project gutenberg. So that problems such as stress corrosion, cracking and fatigue of steam turbine casing, in this work the thermo mechanical analysis of steam turbine casing will be established by finite element method. Full delivery of steam turbine systems for new nuclear.
Differential expansion monitoring measures the change in axial clearances between the machine rotor and casing caused by thermal changes inherent in most machines. Modern turbine technology includes 50 or more stages linked along a horizontal shaft. Turbine hall, looking down from the control room into turbine hall at units 3, 5, and 2 delaware county electric company, chester station, delaware river at south end of ward haer pa,23ches,268. The computeraided design cad files and all associated content posted to this website are created, uploaded, managed and owned by third party users. Pdf online prediction of temperature and stress in steam. The real values of critical speeds should be measured at. The steam may be wet, dry saturated or superheated. See more ideas about steam turbine, abandoned factory and industrial photography. A turbine generator can often produce enough electricity to justify the capital cost of. Full delivery of steam turbine systems for new nuclear power plants in u. Noles references module 23414 turbine operational problems. Both the ends are supported on independent pedestals.
What is differential casing expansion in steam turbine. Excessive thermal expansion ofthe foundation maybe caused, forexample, by beat radiatingfrom a hotsream pipe nearbyif. A consequence of excessive thermal expansion is rotor rubbing. Turbine is a rotary engine that converts the energy of a moving stream of water, steam, or gas into mechanical energy. This prevents mass concentration which would cause high thermal stresses. About 30 months ago acceptance testing was performed on a steam turbine unit that failed to meet the guarantee. In the turbine the fluid flows from the pressure penstock into the turbine machine and first flows through a cascade of guide vanes. When turbine is in service, superheated steam temperature above 540 degree celsius is admitted into the turbine. Each stage consists of a set of moving and stationary blades. 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. P m h 1h 2 where m is the mass flow of the steam through the turbine and h1 and h2 are specific enthalpy of the steam at inlet and outlet of the turbine respectively. This paper narrates the applications of non destructive testing methods in evaluation of steam turbines. Condensate entrapment in the steam supply increases turbine steam rates, reduces the steam turbine efficiency, and causes erosion of steam turbine components governor valves, blading, and nozzles.
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 steam, which results in a closer approach to the ideal reversible expansion process. Turbine supervisory instrumentation system tsi on large steam turbine generator applications. A steam turbine is a mechanical device that extracts thermal energy from pressurized steam and transforms it into mechanical work. Turbine loading leads to positive expansion, while unloading results in negative differential. The basic element in a turbine is a wheel or rotor with addles, propellers, blades, or buckets arranged on its circumference in such a fashion that the moving fluid exerts a tangential force that turns the wheel. Differential expansion sensitivity studies during steam turbine startup article in journal of engineering for gas turbines and power 86 september. These require monitoring to ensure that they do not exceed prescribed limits and endanger the integrity of the turbine. 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. Steam turbine 1 content chapter description page i purpose 2 ii steam turbine types 2 2. A multistage steam turbine is considered to be one of the worlds most powerful engines. A turbinegenerator can often produce enough electricity to justify the capital cost of.
Steam conditions the turbine expansion line or condition curve represents steam conditions prevailing in. Lower steam velocities, results in lower losses and higher theoretical performance drum rotor construction less physically robust design. It combines some theoretical aspects with basic operating procedures to explain how the plant operates. We are commissioning this turbine for the first time. The joint is normally horizontal so that the upper half can be removed leaving the lower half in position with the rotating parts as shown diagrammatically in figure 1.