What happens if we supply a high gland seal pressure for. The success of hightemperature mechanical seals as upgraded glands in small steam turbines required fitting loose parts from socalled component seals. Fire resisting fluid acknowledgements glossary bibliography biographical sketch summary steam turbines consist essentially of a casing to which stationary blades are fixed on the. For understanding the gland sealing system first we have to understand why it is required so there are two main reason. The many variations of steam turbine can be easily accommodated through. Up to nearly 40% load lowpressure auxiliary steam is supplied to the sealing header to seal hpt, ipt, and lpt glands. When a high pressure turbine is operating at sea speed, the pressure of the steam leaking through the shaft gland packing may be slightly higher than the pressure setting of the gland seal regulator. Lp turbine turbine system seal steam system the penultimate section of each gland is supplied with steam from gland steam header, which is maintained at a pressure of 1. As a result, steam turbine maintenance costs and steam losses were reduced along with a decline in reported bearing distress events. A steam powered eductor draws a vacuum and expels the noncondensables that are drawn down with the steam to the gland condenser. Gland steam must have appropriate temperature and pressure which must be controlled during startup. The labyrinth seal has found application in steam turbines. Speed control system turbine gland seal the turbine glands.
A gland sealing steam supply system according to claim 6, wherein said system further includes a gas turbine, and a waste heat recovey boiler used for recovering heat of a waste gas from said gas turbine and having a highpressure steam generating portion consisting of an economizer, a highpressure steam generator and a superheater, and a low. From our simulations it was obvious that the steam turbine tripped due to insufficient inlet oil pressure during the runup. Niskayuna, ny, as well as at cross manufacturings facility in devizes, england. As turbine exhaust is connected to a condenser which is operated below atm pressure so there are chances of air ingres or va. Heat is removed from the bearings by the circulating oil d. Labyrinth packing an overview sciencedirect topics. Us4793141a gland sealing steam supply system for steam. Turbine gland seals are provided to eliminate the possibility of leakage of steam from the turbine through the turbine glands under pressure and ingress of atmospheric air into the turbine under vacuum. If you will increase the gland steam pressure the the vacuum available at the exhaust will decrease or pressure will increase which will decrease th. Ep0268423a2 gland sealing steam supply system for steam. Pdf design and analysis of highpressure casing of a steam turbine. This publication is concerned only with the special carbon gland rings for steam turbine applications and similar glands sealing hot or dry gases. Gland condensers ab progetti vacuum systems steam jet.
Response from high district heating return temperature. Steam turbine basic parts mechanical engineering site. In this post, we will see the difference between api 611 and api 612. The technical data is taken from the bhel steam turbine unit, hyd. To sealing turbine before pulling condensate vacumn before start up, gland sealing steam is extracted from the live steam system or auxiliary steam systeam and decreased both pressure and temperature pressure. Seal steam to the low pressure turbine glands is always provided by the gland seal steam supply header. C61207 this standard specifies the minimum requirements for steam turbines for specialpurpose applications for use in the petroleum, petrochemical, and natural gas industries. Introduction during the past 50 years the gland ring has become a standard method for sealing medium and large diameter shafts. Pdf steam turbines are devices used to convert thermal energy of steam into mechanical energy and. The first question faced by the design engineer is which standard steam turbine as to be selected either api 611 or api 612.
In order to accommodate the range of temperatures experienced throughout the turbine, the system is usually divided into two parts. Simultaneously, gland steam system is started to prevent air inleakage. While selecting a steam turbine as a driver for compressors or pumps for refinerypetrochemical industries. Periodic manual removal of water, then is a technically inferior approach. The steam turbine gland steam seal system is designed to keep steam from leaking out of the turbine and to prevent air from leaking into the turbine. The large, turbine gland sealing systems are basically self sealing, in the sense at a load 40% hp steam coming out from the hpt side could be enough to seal the same on the lpt side. Gland sealing steam supply system for steam turbines. Overlooked gland seal can be big trouble power services. A gland sealing steam supply system according to claim 6, wherein said system further includes a gas turbine, and a waste heat recovery boiler used for recovering heat of a waste gas from said gas turbine and having a highpressure steam generating portion consisting of an economizer, a highpressure steam generator and a superheater, and a low. Carbon packing a watersealed glands and labyrinth seals as used on the highpressure end of condensing turbines. Maintenance and overhaul of steam turbines wgp42 05. The direction of steam flow through the gland seal supply piping is thus reversed from that at low powers. Power engineering 4th class ch 69 flashcards quizlet. Overlooked gland seal can be big trouble december 3, 2015 in steam turbine tips by psgweb.
A turbine stage normally consists of a row of stationary blading and a. Prior to supplying steam to the turbine, the steam supply pipelines have to be drained and heated up. Main turbine generator the main turbine is an 1800 rpm, tandem compound six flow, reheat steam turbine. The main steam system also supplies the steam seal system and the auxiliary steam system when other sources are not available. Rotor extended outside the casing at both side and rear side. A carbon ring comprises three segments held together with a garter spring. Function and system layout the two functions of the turbine glands and seals are.
Focus on bearing housing protector seals steam intrusion often occurs, for example. In case of turbines with cooling water preheating and lowpressure lp. 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. Hp and lp turbines and onto the gland steam condenser. Typically, the steam end and exhaust end gland boxes each carry four to five carbon rings, though there may be more. It also holds glands for steam sealing at each end for. The gland sealing system is designed to supply steam to seal the turbine shaft glands at all operating conditions and to extract leakoff steam from the glands.
Gatbx, university of sheffield, england, 1994 modified by johan andersson. With a steam turbine, a large amount of lubricating oil is supplied to the bearings because. At 4050% turbine load the steam seal supply valve will be fully closed and the system pressure will be maintained at 35 psi by the steam seal. A gland seal system can be as simple as a spray chamber, loop seal and a steam ejector or as complex. Instruction manual for single stage 350, 500, and 700. Morgan special carbon gland rings for steam, air and other gases 1. The integration of the reverse engineering parts process into the steam turbine outage planning and execution ensures that parts can be supplied during ongoing overhauls. Gland sealing system complete heat exchanger steam. Typical benefits of steam turbine mechanical seal technology. For larger steam turbines as per api 612 labyrinth seal are used as shaft seals. There is a large amount of friction between the bearings and the shaft b. Turbine sealing system gland sealing labyrinth seal turbine self sealing duration.
Conventional gland sealing in general purpose steam turbines is accomplished with carbon rings. A gland seal system can be as simple as a spray chamber, loop seal and a steam ejector or as complex as. Specifically, if the turbine exhausts into a vacuum system, it is necessary to inject sealing steam into the seals in order to keep the low pressure end of the turbine from drawing in atmospheric air. Steam turbines turbomachinery magazineturbomachinery. Small heat exchanger used to condense the steam that leaks past the first section of seals on the shaft of a steam turbine. Thus for a gland with a given number of restrictions, there is an associated pressure ratio that produces the maximum leakage through the gland. A game changer for gland sealing in general purpose steam. Gland steam sealing system for steam turbine youtube.
A carbon ring has three segments held together with a garter spring. In the case of condensing steam turbine to prevent the air ingression at the shaft seal by gland condenser and ejector arrangementsas per api 612. Any literature on large condensing steam turbines should include information about the gland steam condenser system. This cause was investigated in using 5 different scenarios. Steam turbine rotors bend during operation, but the bearing and supports are designed to keep the static and dynamic forces under control. However, bending can cause impact between stationary and. The sealing steam first passes through the throttle steam valve and then the safety orifice in order to reduce its pressure to 0. Instruction manual for single stage 350, 500, and 700 frame steam turbines manual 107a. The gland condenser uses cooling water to condense this steam to water which is usually lost to sewer. Each turbine gland is a labyrinthtype seal consisting of seal strips mounted in the turbine. How does the steam turbine gland sealing system work.
A gland sealing steam supply system for steam turbines, adapted to supply steam to a gland portion of a steam turbine which is driven by highpressure steam and lowpressure steam introduced thereinto, comprising a highpressure steam pipe for use in supplying highpressure steam to said turbine, a highpressure steam extraction pipe branching from said highpressure steam pipe, a high. The leakage from the higher pressure sections of the turbine provides the seal steam flow to the lp packing glands. To prevent air from entering into the turbine casing, sealing steam is led to the turbine glands. Typically, the steam end and exhaust end gland boxes each carry four to five carbon rings, though some may have more. While the leakage of steam causes a reduction in cycle efficiency, entry of cold air may cause thermal shock to hot turbine internals. These requirements include basic design, materials. The reason for these specific scenarios was to determine the impact that each of these components sealing surface would have on the oil pressure. As you would be aware that gland sealing steam is provided in condensing turbines. Blade seals are used to prevent the steam leakage between the diaphragm and the shaft. Gland steam sealing system for steam turbine ap nam.
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