SIX WEEKS INDUSTRIAL TRAINING

TULAS INSTITUTE

DEHRADUN

A REPORT

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ON

BHARAT HEAVY ELECTRICALS LIMITEDHARIDWAR

Submitted to: Submitted by:

Mr. B.C. Sharma Ashutosh Saklani

Addi. Engineer M.E. 4th YEAR

Co-coordinator V.T. (HRDC)

BHEL, Hardwar

INTRODUCTIONOF

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BHEL

AN ENGINEERING COMPANY MANUFACTURING AND SUPPLYING

HIGH QUALITY POWER GENERATING EQUIPMENTS IN 70

COUNTRIES.

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ACKNOWLEDGEMENTThe preparation of this project would not have been possible without the guidance and blessings of several people.

I owe my thanks to Mr. A.K. Kushwaha for this encouragement, expert guidance in bringing out this project.

ASHUTOSH SAKLANI

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BLOCK-III

TURBINE AND AUXILIARY BLOCK-III

BHEL, HaridwarBharat Heavy Electricals Ltd. (BHEL) Haridwar has two manufacturing units for manufacture of heavy equipment for industries.

Units:1) Heavy Electrical Equipment Plant (HEEP) and another 2) Central Foundry Forge Plant (CFFP).

Unit details:The Heavy Electricals Equipment Plant (HEEP) located in Haridwar, is one of the major manufacturing plants of BHEL. The core business of HEEP includes design and manufacture of large steam and gas turbines, turbo generators, hydro turbines and generators, large AC/DC motors and so on.

Central Foundry Forge Plant (CFFP) is engaged in manufacture of Steel Castings: Up to 50 Tons per Piece Wt & Steel Forgings: Up to 55 Tons per Piece Wt.

.

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Bharat Heavy Electricals Limited

Type PublicFounded 1956

Headquarters New DelhiKey people K. RAVIKUMAR (Chairperson)

Industry Electrical power industryRevenue Rs 214.97 billion (2008)

Employees 44,305Website www.bhel.com

Bharat Heavy Electricals Limited (BHEL) is the largest engineering and manufacturing enterprise in India in the energy-related and infrastructure sector which includes Power, Railways, Telecom, Transmission and Distribution, Oil and Gas sectors and many more. These sectors have been supplied with endless number of equipments manufactured by BHEL.BHEL was established more than 50 years ago, ushering in the indigenous Heavy Electrical Equipment industry in India. The company has been earning profits continuously since 1971-72 and paying dividends since 1976-77.

It is one of India's nine largest Public Sector Undertakings or PSUs, known as the Navratnas or 'the nine jewels'

The company BHEL manufactures over 180 products under 30 major product groups and caters to core sectors of the Indian Economy viz., Power Generation & Transmission, Industry, Transportation, Telecommunication, Renewable Energy, etc. The wide network of BHEL's 14 manufacturing divisions, four Power Sector regional centre, over 100 project sites, eight service centre and 18 regional offices, enables the Company to promptly serve its customers and provide them with suitable products, systems and services -- efficiently and at competitive prices. The high level of quality & reliability of its products is due to

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the emphasis on design, engineering and manufacturing to international standards by acquiring and adapting some of the best technologies from leading companies in the world, together with technologies developed in its own R&D centre.

As an engineering conglomerate, BHEL offers over a wide spectrum of products and services for core sectors including power generation, transmission and distribution; transportation; and oil and gas. As well as the supply of non-conventional energy systems.

Over 65 percent of power generated in India comes from BHEL-supplied equipment. Overall it has installed power equipment for over 90,000 MW. The present chairman (as of April 2008) of BHEL is Mr. K.Ravikumar.

Headquarters of BHEL is situated in New Delhi.

DETAILS OF THE VARIOUS MANUFACTURING UNIT:BHEL Hardwar is known as the HEEP Heavy Electric Equipment Plant the manufacturing facilities at Hardwar includes STEAM TURBINES GENERATORS MOTORS GAS TURBINES HYDRO TURBINES AND GENERATORS HEAT EXCHANGERS- INCLUDING BOTH OPEN AND CLOSED FEEDWATER HEATERS

THE TESTING FACILITIES OVER HERE ARE ONE OF THE BEST IN ASIA WHICH INCLUDE OSBT OVER SPEED BALANCING TUNNEL WHERE STEAM TURBINES ROTORS ARE TESTED AT SPEEDS ABOVE THE NORMAL AND DYNAMIC BALANCING IS ALSO DONE HERE.

THE HARDWAR UNIT HAS RECENTLY ESTABLISHED A NEW BLADE SHOP WITH FULLY AUTOMATED MACHINES AND SYSTEMS.

Products:

Steam turbine Gas turbine Hydro Turbines Steam Generators HRSG - Heat recovery steam generator Transformers Locomotives Circuit Breakers

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Pumps Motors - BOTH AC AND DC, LT AND HT Generators ESP - Electrostatic precipitator Pulverisers Oil field equipments Valves Boiler drum Headers Economizer Water wall panel Super heater Re-heaters Heat exchangers Pressure vessels Armed recovery vehicle Air preheater Wind mill Fan (mechanical) Super rapid gun mount Soot Blowers

Besides manufacturing these products, BHEL also takes up the onsite erection, commissioning and testing of these equipments. By the end of 2009, it will have a total capacity of 15,000 MW

GENERAL:1.1 Block-III manufactures Steam Turbines, Hydro Turbines, Gas Turbines and

Turbines Blades. Special Tooling for all products are also manufactured in the

Tool Room located in the same block. Equipment layout plan is as per Drawing

appended in Section III. Details of facilities are given in Section II.

1.2 The Block consists of four Bays, namely, Bay-I and II of size 36x378 meters and

36x400 meters respectively and Bay-III and IV of size 24x402 meters and 24x381

metres respectively. The Block is equipped with the facilities of EOT Cranes,

compressed air, Steam, Overspeed Balancing Tunnel, indicating stands for steam

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turbine, rotors, one Test stand for testing 210 MW steam turbines Russian Design,

one Test Stand for Hydro Turbine Guide Apparatus and two separate Test Stands

for the testing of Governing Assemblies of Steam and Hydro Turbines.

1.3 All the parts are conserved, painted and packed before dispatch.

MANUFACTURING FACILITIES:2.1 HYDRO TURBINES

For manufacturing of Hydro Turbines, Bay-I has the following sections:

(a) Circular Components Machining Section – This section is equipped with a

number of large/ heavy size Horizontal and Vertical Boring Machines, Drilling

Machines, Centre Lathes, Marking Table and Assembly Bed. The major

components machined in this section are Spiral Casing with Stay Ring, Spherical

and Disc Valve bodies and Rotors.

(b) Runner and Servo Motor Housing Machining Section – This section is

equipped with NC/CNC and conventional machines comprising Heavy and

Medium size vertical and Horizontal Boring Machines, Centre Lathes, Grinding

machines and Drilling Machines, Marking Table, Assembly Bed, Assembly

Stands for Steam Turbine and Gas Turbine assemblies and Wooden Platform for

overturning heavy components. Hydro Turbine Runners, Servomotors, cylinders,

Labyrinth Ring, Regulating Ring, Stay Ring, Turbine Cover, Lower Ring, Kaplan

Turbine Runner Body and Blades are machined here.

(c) Guide Vanes and Shaft Machining Section – This section is equipped with

Heavy duty Lathe machines upto 16 metres bed, CNC turning machines,

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Horizontal Boring Machine, Heavy planer, Deep Drilling Machine, Boring

Machines, marking Table, Marking Machines and Assembly Beds. Turbine

shafts, Guide Vanes, Journals and Rotors of Spherical and Disc Valves are

machined here. Rotors of Steam Turbines are also machined in this section.

(d) Assembly Section – In this section, assembly and testing of Guide Apparatus,

Disc Valve, Spherical Valves, Servo motor shaft and combined Boring of

coupling holes are done.

(e) Preservation and Packing Section – Final preservation and packing of all the

Hydro Turbine components / assemblies is done here.

(f) Small components Machining Section – This is equipped with Planetary

Grinding Machine, Cylindrical Grinding Machines, small size Lathes, Planers,

Vertical and Horizontal Boring Machines. Small components like Bushes, Levers,

Flanges etc. and Governing assemblies and machines here.

(g) Governing Elements Assembly and Test Stand Section – This section is

equipped with facilities like oil Pumping Unit, Pressure Receiver, Servomotors

etc. for assembly and Testing of Governing Elements.

STEAM TURBINES:The facilities and parts manufactured in the various sections of Steam Turbine

manufacture are as follows:

(a) Turbine casing Machining Section – It is equipped with large size Planer,

Drilling, Horizontal Boring, Vertical Boring, CNC Horizontal and Vertical Boring

machines etc. Fabrication work like casings, Pedestals etc. are received from

Fabrication Block-II.

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(b) Rotor Machining Section – It is equipped with large size machining tools like

Turning Lathe, CNC Lathes, Horizontal Boring Machines, special purpose Fir

tree Groove Milling Machine etc. Some rotor forgings are imported from Russia

and Germany and some are indigenously manufactured at CFFP, BHEL,

Hardwar.

(c) Rotor Assembly Section – This is equipped with Indicating Stand; Small size

Grinding, Milling, Drilling, machines, Press and other devices for fitting Rotors

and Discs. Machined Rotor, Discs and Blades are assembled here. Balancing and

over speeding of Rotor is done on the dynamic balancing machine.

(d) Turbine casing Assembly Section – Machined casings are assembled and

hydraulically tested by Reciprocating Pumps at two times the operating pressure.

(e) Test Station - Test station for testing of 210 MW USSR Steam Turbine at no

load is equipped with condensers, Ejector, Oil Pumps, Oil containers Steam

Connections etc, required for testing. Overspeed testing is done for emergency

Governor. Assembly Test Stands for different modules of Siemens design are

equipped with accessory devices.

(f) Painting Preservation and Packing Section – All the parts are painted,

preserved and packed here for final dispatch.

(g) Bearings and Miscellaneous Parts Machining Section – This section is

equipped with small and medium size basic machine tools, e.g., lathes, Milling

M/c, Horizontal Borer, Vertical Borer, drilling M/c etc. for manufacture of

bearings and other miscellaneous parts of turbine.

(h) Sealing and Diaphragm Machining Section – It is equipped with medium size

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Vertical Boring, Horizontal Boring, Planning, Drilling Machines etc. wherein

castings of sealing Housings, Liner housings, Forgings of Rotor Discs, castings

and fabricated Diaphragms and components are machined. It is also equipped

with CNC machining center.

Precision Horizontal Boring, Plano-Milling machines etc, are for manufacture of

Governing Casting, Servo Casings and other medium parts of governing and Main

Turbine assemblies.

(i) Governing Machining Section – This section is equipped with medium size and

small size lathes, medium CNC lathe, Milling, Grinding, Drilling, Slotting and

Honing Machines. Governing assembly parts are machined here.

(j) Diaphragm and Governing Assembly Section – It is equipped with deflection

testing equipment for Diaphragms, Dynamic Balancing Machine for balancing

Impeller of Centrifugal Oil Pumps and small fittings and assembly equipment.

Governing test stand is equipped with the facilities like Oil Pumping Unit,

Pressure Receiver, Servomotor, overspeed testing of Emergency Governor etc.

(k) Light machine shop – In addition to normal conventional machine tools it is

equipped with CNC Lathes, CNC Milling, CNC Vertical Boring, Precision

Milling, planetary grinding machines etc. for manufacture of small and medium

precision components of governing and other turbine parts.

Turbine:

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A Siemens steam turbine with the case opened.For other uses, see Turbine (disambiguation).

A turbine is a rotary engine that extracts energy from a fluid or air flow. Claude Burdin (1788-1873) coined the term from the Latin turbo, or vortex, during an 1828 engineering competition. Benoit Fourneyron (1802-1867), a student of Claude Burdin, built the first practical water turbine.

The simplest turbines have one moving part, a rotor assembly, which is a shaft with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they rotate and impart energy to the rotor. Early turbine examples are windmills and water wheels.

Gas, steam, and water turbines usually have a casing around the blades that contains and controls the working fluid. Credit for invention of the modern steam turbine is given to British Engineer Sir Charles Parsons (1854 - 1931).

A device similar to a turbine but operating in reverse is a compressor or pump. The axial compressor in many gas turbine engines is a common example.

Theory of operation:

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A working fluid contains potential energy (pressure head) and kinetic energy (velocity head). The fluid may be compressible or incompressible. Several physical principles are employed by turbines to collect this energy:Impulse turbines: 

These turbines change the direction of flow of a high velocity fluid jet. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy. There is no pressure change of the fluid in the turbine rotor blades. Before reaching the turbine the fluid's pressure head is changed to velocity head by accelerating the fluid with a nozzle. Pelton wheels and de Laval turbines use this process exclusively. Impulse turbines do not require a pressure casement around the runner since the fluid jet is prepared by a nozzle prior to reaching turbine. Newton's second law describes the transfer of energy for impulse turbines.

Reaction turbines:  These turbines develop torque by reacting to the fluid's pressure or weight. The pressure of the fluid changes as it passes through the turbine rotor blades. A pressure casement is needed to contain the working fluid as it acts on the turbine stage(s) or the turbine must be fully immersed in the fluid flow (wind turbines). The casing contains and directs the working fluid and, for water turbines, maintains the suction imparted by the draft tube. Francis turbines and most steam turbines use this concept. For compressible working fluids, multiple turbine stages may be used to harness the expanding gas efficiently. Newton's third law describes the transfer of energy for reaction turbines.

Turbine designs will use both these concepts to varying degrees whenever possible. Wind turbines use an airfoil to generate lift from the moving fluid and impart it to the rotor (this is a form of reaction). Wind turbines also gain some energy from the impulse of the wind, by deflecting it at an angle. Cross flow turbines are designed as an impulse machine, with a nozzle, but in low head applications maintain some efficiency through reaction, like a traditional water wheel. Turbines with multiple stages may utilize either reaction or impulse blading at high pressure. Steam Turbines were traditionally more impulse but continue to move towards reaction designs similar to those used in Gas Turbines. At low pressure the operating fluid medium expands in volume for small reductions in pressure. Under these conditions (termed Low Pressure Turbines) blading becomes strictly a reaction type design with the base of the blade solely impulse. The reason is due to the effect of the rotation speed for each blade. As the volume increases, the blade height

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increases, and the base of the blade spins at a slower speed relative to the tip. This change in speed forces a designer to change from impulse at the base, to a high reaction style tip.

Classical turbine design methods were developed in the mid 19th century. Vector analysis related the fluid flow with turbine shape and rotation. Graphical calculation methods were used at first. Formulae for the basic dimensions of turbine parts are well documented and a highly efficient machine can be reliably designed for any fluid flow condition. Some of the calculations are empirical or 'rule of thumb' formulae, and others are based on classical mechanics. As with most engineering calculations, simplifying assumptions were made.

Velocity triangles can be used to calculate the basic performance of a turbine stage. Gas exits the stationary turbine nozzle guide vanes at absolute velocity Va1. The rotor rotates at velocity U. Relative to the rotor; the velocity of the gas as it impinges on the rotor entrance is Vr1. The gas is turned by the rotor and exits, relative to the rotor, at velocity Vr2. However, in absolute terms the rotor exit velocity is Va2. The velocity triangles are constructed using these various velocity vectors. Velocity triangles can be constructed at any section through the blading (for example: hub , tip, midsection and so on) but are usually shown at the mean stage radius. Mean performance for the stage can be calculated from the velocity triangles, at this radius, using the Euler equation:

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Typical velocity triangles for a single turbine stageWhence:

Where:

Specific enthalpy drop across stage Turbine entry total (or stagnation) temperature Turbine rotor peripheral velocity Change in whirl velocity

.

Types of turbines: Steam turbines are used for the generation of electricity in

thermal power plants, such as plants using coal or fuel oil or nuclear power. They were once used to directly drive mechanical devices such as ship's propellers (e.g. the Turbinia), but most such applications now use reduction gears or an intermediate electrical step, where the turbine is used to generate electricity,

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which then powers an electric motor connected to the mechanical load.

Gas turbines are sometimes referred to as turbine engines. Such engines usually feature an inlet, fan, compressor, combustor and nozzle (possibly other assemblies) in addition to one or more turbines.

Transonic turbine. The gas flow in most turbines employed in gas turbine engines remains subsonic throughout the expansion process. In a transonic turbine the gas flow becomes supersonic as it exits the nozzle guide vanes, although the downstream velocities normally become subsonic. Transonic turbines operate at a higher pressure ratio than normal but are usually less efficient and uncommon. This turbine works well in creating power from water.

Contra-rotating turbines. Some efficiency advantage can be obtained if a downstream turbine rotates in the opposite direction to an upstream unit. However, the complication may be counter-productive.

Stator less turbine. Multi-stage turbines have a set of static (meaning stationary) inlet guide vanes that direct the gas flow onto the rotating rotor blades. In a stator less turbine the gas flow exiting an upstream rotor impinges onto a downstream rotor without an intermediate set of stator vanes (that rearrange the pressure/velocity energy levels of the flow) being encountered.

Ceramic turbine. Conventional high-pressure turbine blades (and vanes) are made from nickel-steel alloys and often utilize intricate internal air-cooling passages to prevent the metal from melting. In recent years, experimental ceramic blades have been manufactured and tested in gas turbines, with a view to increasing Rotor Inlet Temperatures and/or, possibly, eliminating air-cooling. Ceramic blades are more brittle than their metallic counterparts, and carry a greater risk of catastrophic blade failure.

Shrouded turbine. Many turbine rotor blades have a shroud at the top, which interlocks with that of adjacent blades, to increase damping and thereby reduce blade flutter.

Shroud less turbine . Modern practice is, where possible, to eliminate the rotor shroud, thus reducing the centrifugal load on the blade and the cooling requirements.

Bladeless turbine uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine.

Water turbines o Pelton turbine , a type of impulse water turbine. o Francis turbine , a type of widely used water turbine.

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o Kaplan turbine , a variation of the Francis Turbine. o Voith , water turbine.

Wind turbine . These normally operate as a single stage without nozzle and interstage guide vanes. An exception is the Éolienne Bollée, which has a stator and a rotor, thus being a true turbine.

Uses of turbines:Almost all electrical power on Earth is produced with a turbine of some type. Very high efficiency turbines harness about 40% of the thermal energy, with the rest exhausted as waste heat.

Most jet engines rely on turbines to supply mechanical work from their working fluid and fuel as do all nuclear ships and power plants.

Turbines are often part of a larger machine. A gas turbine, for example, may refer to an internal combustion machine that contains a turbine, ducts, compressor, combustor, heat-exchanger, fan and (in the case of one designed to produce electricity) an alternator. However, it must be noted that the collective machine referred to as the turbine in these cases is designed to transfer energy from a fuel to the fluid passing through such an internal combustion device as a means of propulsion, and not to transfer energy from the fluid passing through the turbine to the turbine as is the case in turbines used for electricity provision etc.

Reciprocating piston engines such as aircraft engines can use a turbine powered by their exhaust to drive an intake-air compressor, a configuration known as a turbocharger (turbine supercharger) or, colloquially, a "turbo".

Turbines can have very high power density (i.e. the ratio of power to weight, or power to volume). This is because of their ability to operate at very high speeds. The Space Shuttle's main engines use turbo pumps (machines consisting of a pump driven by a turbine engine) to feed the propellants (liquid oxygen and liquid hydrogen) into the engine's combustion chamber. The liquid hydrogen turbo pump is slightly larger than an automobile engine (weighing approximately 700 lb) and produces nearly 70,000 hp (52.2 MW).

Turbo expanders are widely used as sources of refrigeration in industrial processes.

Turbines could also be used as powering system for a remote controlled plane that creates thrust and lifts the plane of the ground. They come in different sizes and could be as small as soda can, still be strong enough to move objects with a weight of 100kg.

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GAS TURBINE:All the components of Gas Turbine are machined and assembled using the

facilities available for manufacturing of steam and hydro turbines except the

following facilities which are procured exclusively for the manufacturing of Gas

Turbine and are installed in the areas specified for gas turbine manufacturing.

A typical axial-flow gas turbine turbojet, the J85, sectioned for displayA gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a combustion chamber in-between. (Gas turbine may also refer to just the turbine element.)

Energy is added to the gas stream in the combustor, where air is mixed with fuel and ignited. Combustion increases the temperature, velocity and volume of the gas flow. This is directed through a nozzle over the turbine's blades, spinning the turbine and powering the compressor.

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Energy is extracted in the form of shaft power, compressed air and thrust, in any combination, and used to power aircraft, trains, ships, generators, and even tanks

History: 150: Hero's Engine (aeolipile) - apparently Hero's steam engine

was taken to be no more than a toy, and thus its full potential not realized for centuries.

1500: The "Chimney Jack" was drawn by Leonardo da Vinci which was turning a roasting spit. Hot air from a fire rose through a series of fans which connect and turn the roasting spit.

1551: Taqi al-Din invented a steam turbine, which he used to power a self-rotating spit.[1]

1629: Jets of steam rotated a turbine that then rotated driven machinery allowed a stamping mill to be developed by Giovanni Branca.

1678: Ferdinand Verbeist built a model carriage relying on a steam jet for power.

1791: A patent was given to John Barber, an Englishman, for the first true gas turbine. His invention had most of the elements present in the modern day gas turbines. The turbine was designed to power a horseless carriage.

1872: A gas turbine engine was designed by Dr Franz Stolze, but the engine never ran under its own power.

1894: Sir Charles Parsons patented the idea of propelling a ship with a steam turbine, and built a demonstration vessel (the Turbinia). This principle of propulsion is still of some use.

1895: Three 4-ton 100 kW Parsons radial flow generators were installed in Cambridge Power Station, and used to power the first electric street lighting scheme in the city.

1903: A Norwegian, Ægidius Elling, was able to build the first gas turbine that was able to produce more power than needed to run its own components, which was considered an achievement in a time when knowledge about aerodynamics was limited. Using rotary compressors and turbines it produced 11 hp (massive for those days). His work was later used by Sir Frank Whittle.

1913: Nikola Tesla patents the Tesla turbine based on the Boundary layer effect.

1914: Application for a gas turbine engine filed by Charles Curtis. 1918: One of the leading gas turbine manufacturers of today,

General Electric, started their gas turbine division. 1920: The practical theory of gas flow through passages was

developed into the more formal (and applicable to turbines) theory of gas flow past airfoils by Dr A. A. Griffith.

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1930: Sir Frank Whittle patented the design for a gas turbine for jet propulsion. His work on gas propulsion relied on the work from all those who had previously worked in the same field and he has himself stated that his invention would be hard to achieve without the works of Ægidius Elling. The first successful use of his engine was in April 1937.

1934: Raúl Pateras de Pescara patented the free-piston engine as a gas generator for gas turbines.

1936: Hans von Ohain and Max Hahn in Germany developed their own patented engine design at the same time that Sir Frank Whittle was developing his design in England.

Theory of operation:Gas turbines are described thermodynamically by the Brayton cycle, in which air is compressed isentropic ally, combustion occurs at constant pressure, and expansion over the turbine occurs isentropic ally back to the starting pressure.

In practice, friction and turbulence cause:

1. Non-isentropic compression: for a given overall pressure ratio, the compressor delivery temperature is higher than ideal.

2. Non-isentropic expansion: although the turbine temperature drop necessary to drive the compressor is unaffected, the associated pressure ratio is greater, which decreases the expansion available to provide useful work.

3. Pressure losses in the air intake, combustor and exhaust: reduces the expansion available to provide useful work.

Brayton cycle:As with all cyclic heat engines, higher combustion temperature means greater efficiency. The limiting factor is the ability of the steel, nickel, ceramic, or other materials that make up the engine to withstand heat and pressure. Considerable engineering goes into keeping the turbine parts cool. Most turbines also try to recover exhaust heat, which otherwise is wasted energy. Recuperators are heat exchangers that pass exhaust heat to the compressed air, prior to combustion. Combined cycle designs pass waste heat to steam

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turbine systems. And combined heat and power (co-generation) uses waste heat for hot water production.

Mechanically, gas turbines can be considerably less complex than internal combustion piston engines. Simple turbines might have one moving part: the shaft/compressor/turbine/alternative-rotor assembly (see image above), not counting the fuel system.

More sophisticated turbines (such as those found in modern jet engines) may have multiple shafts (spools), hundreds of turbine blades, movable stator blades, and a vast system of complex piping, combustors and heat exchangers.

As a general rule, the smaller the engine the higher the rotation rate of the shaft(s) needs to be to maintain top speed. Turbine blade top speed determines the maximum pressure that can be gained; this produces the maximum power possible independent of the size of the engine. Jet engines operate around 10,000 rpm and micro turbines around 100,000 rpm.

Thrust bearings and journal bearings are a critical part of design. Traditionally, they have been hydrodynamic oil bearings, or oil-cooled ball bearings. These bearings are being surpassed by foil bearings, which have been successfully used in micro turbines and auxiliary power units.

Types of gas turbines: Aero derivatives and Jet engines

Air breathing jet engines are gas turbines optimized to produce thrust from the exhaust gases, or from ducted fans connected to the gas turbines. Jet engines that produce thrust primarily from the direct impulse of exhaust gases are often called turbojets, whereas those that generate most of their thrust from the action of a ducted fan are often called turbofans or (rarely) fan-jets.

Gas turbines are also used in many liquid propellant rockets, the gas turbines are used to power a turbo pump to permit the use of lightweight, low pressure tanks, which saves considerable dry mass.

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Aero derivatives are also used in electrical power generation due to their ability to startup, shut down, and handle load changes more quickly than industrial machines. They are also used in the marine industry to reduce weight. The GE LM2500 and LM6000 are two common models of this type of machine.

Auxiliary power units:Auxiliary power units (APUs) are small gas turbines designed for auxiliary power of larger machines, such as those inside an aircraft. They supply compressed air for aircraft ventilation (with an appropriate compressor design), start-up power for larger jet engines, and electrical and hydraulic power.

Industrial gas turbines for electrical generation

GE H series power generation gas turbine. This 480-megawatt unit has a rated thermal efficiency of 60% in combined cycle configurations.Industrial gas turbines differ from aero derivative in that the frames, bearings, and blading is of heavier construction. Industrial gas turbines range in size from truck-mounted mobile plants to enormous, complex systems.[clarification needed] They can be particularly efficient—up to 60%—when waste heat from the gas turbine is recovered by a heat recovery steam generator to power a conventional steam turbine in a combined cycle configuration.[citation needed] They can also be run in a cogeneration configuration: the exhaust is used for space or water heating, or drives an absorption chiller for cooling or refrigeration. A cogeneration configuration can be over 90% efficient.[citation needed] The power turbines in the largest industrial gas turbines operate at 3,000 or 3,600 rpm to match the AC power grid frequency and to avoid the need for a reduction gearbox.[citation

needed] Such engines require a dedicated enclosure, both to protect the engine from the elements and the operators from the noise.

Simple cycle gas turbines in the power industry require smaller capital investment than either coal or nuclear power plants and can be scaled to generate small or large amounts of power.[citation needed] Also, the actual construction process can take as little as several

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weeks to a few months, compared to years for base load power plants. Their other main advantage is the ability to be turned on and off within minutes, supplying power during peak demand. Because they are less efficient than combined cycle plants, they are usually used as peaking power plants, which operate anywhere from several hours per day to a few dozen hours per year, depending on the electricity demand and the generating capacity of the region. In areas with a shortage of base load and load following power plant capacity, a gas turbine power plant may regularly operate during most hours of the day and even into the evening. A typical large simple cycle gas turbine may produce 100 to 300 megawatts of power and have 35–40% thermal efficiency. The most efficient turbines have reached 46% efficiency.

Compressed air energy storage:One modern development seeks to improve efficiency in another way, by separating the compressor and the turbine with a compressed air store. In a conventional turbine, up to half the generated power is used driving the compressor. In a compressed air energy storage configuration, power, perhaps from a wind farm or bought on the open market at a time of low demand and low price, is used to drive the compressor, and the compressed air released to operate the turbine when required.

Turbo shaft engines:Turbo shaft engines are often used to drive compression trains (for example in gas pumping stations or natural gas liquefaction plants) and are used to power almost all modern helicopters. The first shaft bears the compressor and the high speed turbine (often referred to as "Gas Generator" or "N1"), while the second shaft bears the low speed turbine (or "Power Turbine" or "N2"). This arrangement is used to increase speed and power output flexibility.

Radial gas turbines:In 1963, Jan Mowill initiated the development at Kongsberg Våpenfabrikk in Norway. Various successors have made good progress in the refinement of this mechanism. Owing to a configuration that keeps heat away from certain bearings the durability of the machine is improved while the radial turbine is well matched in speed requirement.

Scale jet engines:

Scale jet engines are scaled down versions of this early full scale engine. Also known as miniature gas turbines or micro-jets.

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Many model engineers relish the challenge of re-creating the grand engineering feats of today as tiny working models. Naturally, the idea of re-creating a powerful engine such as the jet, fascinated hobbyists since the very first full size engines were powered up by Hans von Ohain and Frank Whittle back in the 1930s.

Recreating machines such as engines to a different scale is not easy. Because of the square-cube law, the behaviour of many machines does not always scale up or down at the same rate as the machine's size (and often not even in a linear way), usually at best causing a dramatic loss of power or efficiency, and at worst causing them not to work at all. An automobile engine, for example, will not work if reproduced in the same shape at the size of a human hand.

With this in mind the pioneer of modern Micro-Jets, Kurt Schreckling, produced one of the world's first Micro-Turbines, the FD3/67. This engine can produce up to 22 Newton’s of thrust, and can be built by most mechanically minded people with basic engineering tools, such as a metal lathe. Its radial compressor, which is cold, is small and the hot axial turbine is large experiencing more centrifugal forces, meaning that this design is limited by Mach number. Guiding vanes are used to hold the starter, after the compressor impeller and before the turbine. No bypass within the engine is used.

Micro turbines:

A micro turbine designed for DARPAAlso known as:

Turbo alternators Micro Turbine (registered trademark of Capstone Turbine

Corporation) Turbo generator (registered trade name of Honeywell Power

Systems, Inc.)

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Micro turbines are becoming widespread for distributed power and combined heat and power applications. They are one of the most promising technologies for powering hybrid electric vehicles. They range from hand held units producing less than a kilowatt, to commercial sized systems that produce tens or hundreds of kilowatts.

External combustion:Most gas turbines are internal combustion engines but it is also possible to build an external combustion gas turbine which is, effectively, a turbine version of a hot air engine.

External combustion has been used for the purpose of using pulverized coal or finely ground biomass (such as sawdust) as a fuel. External combustion gas has been used both directly and indirectly. In the direct system, the combustion products travel through the power turbine. In the indirect system, a heat exchanger is used and clean air travels through the power turbine. The thermal efficiency is lower in the indirect type of external combustion; however the blades are not subjected to combustion products.

Advances in technology:Gas turbine technology has steadily advanced since its inception and continues to evolve; research is active in producing ever smaller gas turbines. Computer design, specifically CFD and finite element analysis along with material advances, has allowed higher compression ratios and temperatures, more efficient combustion and better cooling of engine parts. On the emissions side, the challenge in technology is increasing turbine inlet temperature while reducing peak flame temperature to achieve lower NOx emissions to cope with the latest regulations. Additionally, compliant foil bearings were commercially introduced to gas turbines in the 1990s. They can withstand over a hundred thousand start/stop cycles and eliminated the need for an oil system.

On another front, microelectronics and power switching technology have enabled commercially viable micro turbines for distributed and vehicle power

a) Hydraulic Lifting Platform

This facility is used for assembly and disassembly of G.T. Rotor. This is a

hydraulically operated platform which travels upto 10 M height to facilitate

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access to different stages of Rotor. This is installed in Bay-I assembly area.

b) CNC Creep Feed Grinding M/c.

This is installed in Gas Turbine machining area Bay-II Extn. This M/c grinds the

hearth serration on rotor disc faces. Hirth serrations are radial grooves teeth on

both the faces of rotor discs. Torque is transmitted trough these serrations, which

are very accurately ground.

c) External Broaching Machine

This machine is installed in GT machining area and is used to make groove on the

outer dia of rotor discs for the fitting of moving blades on the discs.

d) CNC Facing Lathe

This machine is installed in GT machining area and is used basically for facing

rotor disc but can turn other components also.

e) CNC Turning Lathe

This machine is installed in Bay-I Heavy Machine Shop and is used to turn Tie

Rods of Gas Turbine, which have very high length / diameter ratio. Tie-Rod is a

very long bolt (length approx. 10 meter & dia 350 mm) which is used to assembly

and hold the gas turbine rotor discs to form a composite turbine rotor.

f) Wax Melting Equipment

This is low temp. electric furnace installed in Gas Turbine blading area in Bay-II.

It is used to mix and melt Wax and Colaphonium, which is required to arrest the

blade movement during the blade tip machining of stator blade rings.

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g) Gas Turbine Test Bed

This test bed is installed near the Gas Turbine Machining area in Bay-II. This

facility is used to finally assemble the gas turbine. Combustion chambers are not

assembled here, which are assembled with main assembly at the site.

h) Combustion Chamber Assembly Platform

This facility is a 3 Tier Platform installed in Bay-I assembly area and is used for

assembly of Combustion Chambers of Gas Turbine.

MANUFACTURING PROCESS:

3.1 HYDRO TURBINES

The major processes involved in various Hydro Turbine Sections are as follows:

Marking and checking of blanks – manual as well as with special marking

M/c.

Machining on Horizontal Boring, Vertical Boring, Lathes etc. as the case may

be on CNC /Conventional Machines.

Intermediate assembly operation is carried out on the respective assembly

beds provided.

Then the assembly is machined as per requirement.

The sub-assemblies are further assembled for hydraulic/functional testing.

Hydraulic testing is done using a power driven triple piston horizontal

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hydraulic pump which can generate a pressure of 200 Kg/Cm2. It can also be

carried out using a power pack.

On Governing elements / assembly and test stand, the components / sub-

assemblies / assemblies are tested up to a hydraulic pressure of 200 Kg / c m2

using the piston pump. Oil testing upto 40 Kg / c m2 is carried out with oil

pumping unit, which is permanently installed on this bed.

Steam turbine:

A rotor of a modern steam turbine, used in a power plant

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A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884.

It has almost completely replaced the reciprocating piston steam engine (invented by Thomas Newcomen and greatly improved by James Watt) primarily because of its greater thermal efficiency and higher power-to-weight ratio. Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator – about 80% of all electricity generation in the world is by use of steam turbines. 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.

History:The first device that may be classified as a reaction steam turbine was little more than a toy, the classic Aeolipile, described in the 1st century by Hero of Alexandria in Roman Egypt. More than a thousand years later, the first impact steam turbine with practical applications was invented in 1551 by Taqi al-Din in Ottoman Egypt, who described it as a prime mover for rotating a spit. Similar smoke jacks were later described by John Wilkins in 1648 and Samuel Pepys in 1660. Another steam turbine device was created by Italian Giovanni Branca in 1629.

The modern steam turbine was invented in 1884 by the Englishman Sir Charles Parsons, whose first model was connected to a dynamo that generated 7.5 kW of electricity. After the invention of Parson's steam turbine, which made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare, the world would never be the same again. His patent was licensed and the turbine scaled-up shortly after by an American, George Westinghouse. A number of other variations of turbines have been developed that work effectively with steam. The de Laval turbine (invented by Gustaf de Laval) accelerated the steam to full speed before running it against a turbine blade. This was good, because the turbine is simpler, less expensive and does not need to be pressure-proof. It can operate with any pressure of steam. It is also, however, considerably less efficient. The Parson's turbine also turned out to be relatively easy to scale-up. Parsons had the satisfaction of seeing his invention adopted for all major world power stations. The size of his generators had increased from his first 7.5 kW set up to

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units of 50,000 kW capacity. He knew that the total output from turbo-generators constructed by his firm C. A. Parsons and Company and by their licensees, for land purposes alone, had exceeded thirty million horse-power. Within Parson's lifetime the generating capacity of a unit was scaled-up by about 10,000 times.

Parsons turbine from the Polish destroyer ORP Wicher II

Steam Supply and Exhaust Conditions:These types include condensing, no condensing, reheat, extraction and induction.

Noncondensing or backpressure turbines are most widely used for process steam applications. The exhaust pressure is controlled by a regulating valve to suit the needs of the process steam pressure. These are commonly found at refineries, district heating units, pulp and paper plants, and desalination facilities where large amounts of low pressure process steam are available.

Condensing turbines are most commonly found in electrical power plants. These turbines exhaust steam in a partially condensed state, typically of a quality near 90%, at a pressure well below atmospheric to a condenser.

Reheat turbines are also used almost exclusively in electrical power plants. In a reheat turbine, steam flow exits from a high pressure section of the turbine and is returned to the boiler where additional superheat is added. The steam then goes back into an intermediate pressure section of the turbine and continues its expansion.

Extracting type turbines are common in all applications. In an extracting type turbine, steam is released from various stages of the turbine, and used for industrial process needs or sent to boiler feed water heaters to improve overall cycle efficiency. Extraction flows may be controlled with a valve, or left uncontrolled.

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Induction turbines introduce low pressure steam at an intermediate stage to produce additional power.

Casing or Shaft Arrangements:These arrangements include single casing, tandem compound and cross compound turbines. Single casing units are the most basic style where a single casing and shaft are coupled to a generator. Tandem compound are used where two or more casings are directly coupled together to drive a single generator. A cross compound turbine arrangement features two or more shafts not in line driving two or more generators that often operate at different speeds. A cross compound turbine is typically used for many large applications.

Principle of Operation and Design:An ideal steam turbine is considered to be an isentropic process, or constant entropy process, in which the entropy of the steam entering the turbine is equal to the entropy of the steam leaving the turbine. No steam turbine is truly “isentropic”, however, with typical isentropic efficiencies ranging from 20%-90% based on the application of the turbine. The interior of a turbine comprises several sets of blades, or “buckets” as they are more commonly referred to. One set of stationary blades is connected to the casing and one set of rotating blades is connected to the shaft. The sets intermesh with certain minimum clearances, with the size and configuration of sets varying to efficiently exploit the expansion of steam at each stage.

Operation and Maintenance:When warming up a steam turbine for use, the main steam stop valves (after the boiler) have a bypass line to allow superheated steam to slowly bypass the valve and proceed to heat up the lines in the system along with the steam turbine. Also a turning gear is engaged when there is no steam to the turbine to slowly rotate the turbine to ensure even heating to prevent uneven expansion. After first rotating the turbine by the turning gear, allowing time for the rotor to assume a straight plane (no bowing), then the turning gear is disengaged and steam is admitted to the turbine, first to the astern blades then to the ahead blades slowly rotating the turbine at 10 to 15 RPM to slowly warm the turbine.

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Problems with turbines are now rare and maintenance requirements are relatively small. Any imbalance of the rotor can lead to vibration, which in extreme cases can lead to a blade letting go and punching straight through the casing. It is, however, essential that the turbine be turned with dry steam. If water gets into the steam and is blasted onto the blades (moisture carryover) rapid impingement and erosion of the blades can occur, possibly leading to imbalance and catastrophic failure. Also, water entering the blades will likely result in the destruction of the thrust bearing for the turbine shaft. To prevent this, along with controls and baffles in the boilers to ensure high quality steam, condensate drains are installed in the steam piping leading to the turbine.

Speed regulation:The control of a turbine with a governor is essential, as turbines need to be run up slowly, to prevent damage while some applications (such as the generation of alternating current electricity) require precise speed control. Uncontrolled acceleration of the turbine rotor can lead to an overspeed trip, which causes the nozzle valves that control the flow of steam to the turbine to close. If this fails then the turbine may continue accelerating until it breaks apart, often spectacularly. Turbines are expensive to make, requiring precision manufacture and special quality materials.

Direct drive:Electrical power stations use large steam turbines driving electric generators to produce most (about 80%) of the world's electricity. Most of these centralized stations are of two types: fossil fuel power plants and nuclear power plants. The turbines used for electric power generation are most often directly coupled to their generators. As the generators must rotate at constant synchronous speeds according to the frequency of the electric power system, the most common speeds are 3000 r/min for 50 Hz systems, and 3600 r/min for 60 Hz systems. In installations with high steam output, as may be found in nuclear power stations, the generator sets may be arranged to operate at half these speeds, but with four-pole generators.

(a) Machine section – Castings, Forgings, welded structures and other blanks

are delivered to this section. The manufacturing process is based on the use of high

efficiency carbide tipped tools, high speed and high feed machining techniques with

maximum utilization of machine – tool capacity and quick acting jigs and fixtures.

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(b) Assembly Section – Casings and Governing assemblies are hydraulically tested

for leakage on special test Bed. Assembled unit of governing and steam

distribution systems are tested on Governing Test Bed. General Assembly and

testing of Steam Turbine is carried out on the main Test Bed in Bay-II.

(c) Painting, Preservation and Packing – After testing the turbine, it is

disassembled and inspected. Then the parts are painted, conserved and packed for

final dispatch.

3.3 GAS TURBINE

The major processes involved in manufacturing Gas Turbine in various sections

of Bk-III are as follows:

a) Machining

Castings, Forgings, welded structures and other blanks are received from

concerned agencies in the respective sections. These are machined keeping in

view optimum utilization of machine tools and toolings. Special jigs and fixtures

are made available to facilitate accurate and faster machining. Proper regime and

tool grades have been established to machine the materials like inconel, which

have poor machinablity.

b) Main Assembly

Final assembly is done on test bed. Parts are assembled to make sub-assemblies.

These sub-assemblies are again machined as per technological and design

requirements and are made ready for final assembly. After assembly and

insulation assembled Gas Turbine is sento site.

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c) Rotor Assembly

The rotor is assembled on Hydraulic Lifting Platform and sent to main assembly,

where after checking clearances, it is sent for machining. After balancing, turbine

side of rotor is disassembled, inner casing is fitted and rotor reassembled. This

work is also carried out on Hydraulic Lifting Platform. Finally rotor is sent for

assembly on test bed.

d) Combustion Chamber Assembly

This assembly is carried out on 3 tier platform installed for this purpose in Bay-I

assembly. After machining of all components, ceramic tiles are fitted in flame

tube. Burner and piping etc. is fitted in dome and combustion chamber is finally

assembled. It is directly sent to site after insulation.

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