STEAM TURBINE BOOKS PDF
PDF Drive is your search engine for PDF files. As of today we have 78,, eBooks for you to download for free. No annoying ads, no download limits, enjoy . and for making it possible to finish the book at this time. For placing at my disposal a great deal of information regarding the latest results in steam turbine. PEMP. RMD Session Objectives. This session is intended to discuss the following: ❑ Classification of steam turbines. ❑ Compounding of steam turbines.
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Classification of steam turbines. • Working principles. • Pressure and velocity compounding. • Losses in steam turbines. Losses in steam turbines. • Design. PDF | Chapter-4 (Steam Turbines): CLASSIFICATION OF STEAM In book: Power Plant Lecture Notes, Edition: 1, Chapter: CHAPTER Steam turbine. A rotor of a modern steam turbine, used in a power plant. A steam turbine book Dampf und Gas-Turbinen (English Steam and Gas Turbines). .. [ 18] myavr.info  Streeter.
Here the shrouding is machined integral with the blade, the blades being fixed together by a strip of metal passed through the top of the shrouding and riveted to each blade. In other cases the shrouding is again machined integral with the blade and the sections are secured together by fitting a wire through an open groove in the top of the shrouding and then rolling the top edges of this groove over the top of the wire, as in c.
Lacing wires may be fitted through holes drilled in the blades and brazed in position, or the wires may be in the form of a tube and crimped either side of the hole.
In some cases, to assist steam flow the wires may be of aero section. Expansion gaps are usually allowed in both shrouding and lacing-.
Damping wires are used to assist in reducing vibrations. Blade fixing arrangements The high rotational speeds of modern turbine rotors produce severe centrifugal stresses which require very often complex root fixing arrangements for the blades to provide adequate resistance.
At one or more points around the disc the T-section is cut away to allow the blades to be fitted. When the wheel has been completely bladed, the last blade is fitted over this plain section and riveted into position.
The blade as shown in b is fitted axially and crimped at either side into t lit root to prevent displacement.?
The week at Siemens
The root form shown in c is used on blades subject to high stresses, and is designed so that additional contact surface can be gained without weakening to any great extent either the blade root or wheel rim sides. This could occur if the blade root or wheel rim sides-are cut deep enough to provide adequate surface area to withstand the load.
In the latter case a gate has to be cut into the periphery of the wheel to allow the blade to be entered. Once entered into the groove the blade is tapped round until it comes against a stopper adjacent to the other side of the gate. Once the groove is full the stopper is removed, the last blade fitted and a stop piece fitted into the gate. This is usually secured with a countersunk screw and the edge peened over.
The gates are usually staggered around successive grooves along the length of the rotor to assist balancing. A material suitable for turbine blades operating over the steam temperature range 0 to would have the following constituents: 0. Nickel Casing blades. Blade stresses and defects Being stationary the casing blades of a Curtis turbine are not subject to centrifugal stresses and therefore they do not require a complicated root form. They should, however, be a tight fit in the groove as they can vibrate, which in turn may cause fretting.
Frequently the design of the turbine calls for the nozzles and guide blades to cover only a comparatively small inlet rc and a carrier ring may then be fitted round part of the casing to carry the bladesEnd stop blades are required at the horizontal joint or at the ends of the blade ring"fo keep the blades in position-a typical arrangement is shown in Fig. Tie force exerted by the steam driving the turbine is tangential er 28 and acts at near mid-height of the blade producing a bending stress which is largest nearest the blade root.
This stress can be very large whe n taming or reversing.
Sudden changes i n load o an alternator can also cause speed vana lot s which can add to stresses already present. On HP plants silica may ciuie such a particularly-at turbine temperproblem atures of about C where it forms a hard coffee-coloured deposit on the blades.
Deficiencies in the treatment of the boiler water eventually cause deposits in the turbines which change the steam flow areas resulting in pressure changes. If the deposits occur in the nozzle area the steam flow will be reduced, with pressures dropping throughout the turbine and the output falling.
If the flow area of other stages is reduced the steam flow will remain fairly constant, but stage pressures in the turbine will adjust to allow for a higher pressure drop over each of the affected stages. For example, if the trouble occurs after the first stage, the pressure before that stage will increase, the first, second and third bleed pressures will fall, while the cross-over pressure will initially fall, then steady.
In order to obtain a reasonably accurate test of the plant performance the bleeds should be shut off so that the turbine is isolated and there is no interference from the rest of the steam cycle.
Excessive end thrust on the rotor may also arise. In this situation steam leaks up through the 0. Having no escape path, this steam builds up pressure to that of the superheater outlet, on the main valve, pressing the valve lid onto its seat with a load of approximately 70kN.
When the valve is opened, the initial movement of the hand-wheel lifts the valve spindle until the collars come against guide 5.
Steam Turbines by Hubert E. Collins
This initial movement of approximately 0. Care should be taken not to jam the manoeuvring valve thus and any differential expansion may then be easily absorbed by the belleville washers. Under these conditions the valve should be steam tight and attempts to reduce any leakage by jamming the valve shut are useless considering the load being exerted by the steam pressure on the valve lid.
In such conditions the valve should be overhauled. The valve lid, bush and spindle are made from stainless steel, with the main valve seat being stellited cast steel.
Instead of a gland using some form of asbestos packing to prevent leakage around the spindle, some valves use a labyrinth form of packing with a steam leakoff to the gland condenser or highpressure drains tank. In turbines of all types, arrangements must be made for the casing to expand and contract under the influence of fluctuations in steam temperature.
In a large number of designs the rotor thrust collar and the associated thrust block are placed at the for'd end of the turbine and this locates the rotor in the turbine casing. The flexible coupling between the rotor and the.
The' turbine casing is usually supported on a pedestal from the tank tops at the after end or attached to brackets fixed to the gear box. The supporting palms here hold the casing firmly in position relative to the gearbox so that there can be no fore and aft movement between these, male and female spigots with elongated bolt holes being used for this as in type 1, Fig. The spigots and elongated holes, however, do.
The spigots may be of dissimilar metals to prevent seizure.
At the for'd end 30 Turbine expansion arrangements down a hole drilled into the spindle, past the supplementary valve seat 1 to the turbines. This allows the main valve lid to become balanced and very little effort should now be required to open the main valve admitting steam to the turbines.
When the valve is closed the reverse happens, the initial movement of the spindle moves it down so that the supplementary valve is closed, and the main valve may then be closed easily, the pressure building up on the back of the main valve as this valve closes, the steam pressure eventually holding the valve shut as described previously.
The valve spindle and operating sleeve run in ball races at the hand-wheel end and it is possible to feel the supplementary valve shut as the valve is closed. The hand-wheel can be moved a further half-turn after the valve is fully closed, this movement tending to compress the belleville spring washers 6. If the hand-wheel is turned too far in the shut direction, all the free travel in the belleville springs can be similar palms are used to attach the casing to the for'd bearing and thrust housing.
These palms may use male and female keys or spigots as at the after end with the keys allowing thwartships expansion, whilst expansion in the longitudinal direction is catered for by asliding foot arrangemen t or p anting plates as shown. As an alternative to the male and female spigot at the for'd end, the palm may simply have an enlarged hole with a stud passing through fitted with a nut. This then allows expansion in both longitudinal direction and thwartships, but the sliding foot or panting plate arrangement will still be used to provide longitudinal expansion.
To hold the casing in transverse or axial alignment with the gear box, vertical keys as in Fig. These allow vertical expansion to take place, but they must be a good fit to ensure no misalignment takes place. When a turbine is being warmed through great care should be taken to see that the expansions allowed for are actually taking place.
On land, steam turbines are now almost universally preferred to reciprocating engines for electric generating stations; while low-pressure turbines are largely utilised—as auxiliaries to reciprocating engines—in iron works, factories, and engineering establishments. One of the most notable developments in modern mechanical engineering consists in the adoption of methods for utilising heat which had previously been wasted in carrying on manufacturing processes. In this endeavour to secure increased economy the steam turbine has played a great part, although its successful applications have unquestionably been greatly assisted by the work of electrical engineers.
Superheating, higher vacuums and greatly improved arrangements for condensing steam have necessarily had to be devised in order that the full efficiency of turbines might be realised; and it is worth noting that these advances have not only produced beneficial results in association with the use of steam turbines. Their range of usefulness has been much wider, and has affected the economical use of earlier types of reciprocating engines, both afloat and ashore.
Steam Turbine Design. By Dr. Google Scholar Salisbury, J. Reprinted Steam Turbines and Their Cycles. Robert E.
Google Scholar Special Section. Steam Turbines.
Google Scholar Spencer, R. Cotton, and C. Google Scholar Westinghouse Electric Corporation.The angle of the helix is selected so that one end of the tooth enters mesh before the opposite ends of preceding teeth have disengaged. The quantity of steam discharged will depend upon, the drop between inlet and exhaust pressure, but the maximum quantity the nozzle is capable of discharging occurs when the discharge or exhaust pressure is approximately 0. However, the design does produce a long rotor which tends to be very susceptible to sagging and distortion.
Excessive heating should be avoided and the rate of heating should be carefully controlled to prevent local breakdown of the oil in way of the heater. In the latter case a gate has to be cut into the periphery of the wheel to allow the blade to be entered. What are auxiliary systems? For ahead movements the control oil pressure N to the ahead servo motor increases when the spring plate in the impulse converter is kept close to 58 the oil nozzle.
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