1.Acknowledgement

1.Acknowledgement It does not take much strength to do things, but it requires a great deal of strength to decide what to do.Elbert Hubbard

Success in such comprehensive report cant be achieved single handed. It is the team effort that sail the ship to the coast. So I would like to express my sincere thanks to my mentor.

I am also grateful to the management of Bharat Heavy Electrical limited (BHEL), Haridwar for permitting me to have training during June 26th June to 26th July, 2014.

It gives me immense pleasure to express my gratitude to the department of Mechanical Engineering for their prudent response in course of completing my training report. I am highly indebted to, MR. H.N GUPTA, their guidance and whole hearted inspiration; it has been of greatest help in bringing out the work in the present shape. The direction, advice, discussion and constant encouragement given by them has been so helpful in completing the work successfully.

BHEL AN OVERVIEWBHEL or the Bharat Heavy Engineering Limited is one of the largest engineering and manufacturing organizations in the country and the BHEL, Haridwar is their gift to Uttarakhand. With two large manufacturing plants, BHEL in Haridwar is among the leading industrial organizations in the state. It has established a Heavy Electrical Equipment Plant or HEEP and a Central Foundry Forge Plant or CFFP in Haridwar.

The Heavy Electrical Equipment Plant in Haridwar designs and manufactures turbo generators, AC and DC motors, gas turbines and huge steams. The Central Foundry Forge Plant in Haridwar deals with steel castings and manufacturing of steel forgings.

The BHEL plants in Haridwar have earned the ISO - 9001 and 9002 certificates for its high quality and maintenance. Situate in Ranipur near Haridwar, the Bharat Heavy Engineering Limited employs over 8,000 people.

CLASSIFICATION OF BLOCK 3 Block 3 is divided into 4 bays- Bay-1 is further divided into three parts:

1. HMS-In this shop heavy machine work is done with the help of different NC & CNC machines such as center lathes, vertical and horizontal boring & milling machines. Asias largest vertical boring machine is installed here and CNC horizontal boring milling machines from Skoda of Czechoslovakia.

2. Assembly section - In this section assembly of turbines are done. Blades of turbine are 1st assemble on the rotor & after it, rotor is transported to balancing tunnel where the balancing is done. After balancing the rotor, rotor & casings both internal & external are transported to the customer. Total assembly of turbine is done in the company which purchased it by BHEL.

3. Osbt (over speed balancing tunnel)-In this section, rotors of all type of turbines like LP(low pressure) , HP(high pressure)& IP(intermediate pressure) rotors of steam turbine , rotors of gas & hydro turbine are balanced .In a large tunnel ,maximum vacuum of 1 torr (1 mm hg). Is created with the help of pumps & after that rotor is placed on pedestal and rotated with speed up to 4500 rpm .After it in a computer control room the axis of rotation of rotor is seen with help of computer & the rotor is balanced by inserting the small balancing weight into the dovetail cut on rotor.

Bay 2 is divided in to 2 parts:

1.Hms In this shop several operations on various components of steam turbine like LP,IP & HP rotors, internal & external casing are done with the help of different NC & CNC machines like grinding, drilling, vertical & horizontal milling and boring machines, center lathes, planer, kopp milling machine.

2.Assembly section In this section assembly of steam turbines up to 660 MW are assembled. First of all, moving blades are inserted in the grooves cut on circumference of rotor, then rotor is balanced in osbt in bay-1. After this, final assembly operation is done in which guide blades are assembled inside the internal casing & then rotor is fitted inside this casing. Then internal casing with rotor is inserted into the external casing for close tolerance check. Then rotor and casing are dissembled for transportation to the site.

Bay 3 is divided into 2 parts:

1 Bearing section In this section, journal bearings are manufactured which are used to support the turbine and to overcome the vibration & rolling friction by providing the proper lubrication.

2 Turning section In this section small lathe machines, milling & boring machines, grinding machines & drilling machines are installed. In this section small jobs are manufactured like rings, studs, disks etc.

Bay-4 is divided into 3 parts:

1 Tbm (turbine blade manufacturing) shop- In this shop solid blade of both steam & gas turbine are manufactured. Several CNC & NC machines are installed here such as copy mill, grinding machine, rhomboid milling machine, t- root machine center, vertical and horizontal boring machine etc.

2.Turning section- Same as the turning section in bay-3, there are several small machines like lathes machines, milling, boring, grinding machines etc.

3.Heat treatment shop- In this section, there are several heat treatment operations performed for achieving desired hardness of different components. Operations performed are carburizing, nitriding etc.

Construction: steam flowBHEL has the capability to design, manufacture and commission steam turbines of up to 1000 MW rating for steam parameters ranging from 30 bars to 300 bars pressure and initial & reheat temperatures up to 600 C.Turbines are built on the building block system, consisting of modules suitable for a range of output and steam parameters. For a desired output and steam parameters appropriate turbine blocks can be selected.The turbine tandem compound machine with HP, IP & LP parts. The HP parts is a single flow cylinder and the IP &LP are double flow cylinder. The individual turbine rotors and generators are connected by rigid coupling.The hp cylinder has a throttle control. The initial steam is admitted before the balding by two combined main steam stop and control valve. The two exhaust from hp is send to reheat before supplying in ip via two combined reheat stop and control valve. Bleed are arranged at several points of the turbine.

Parts of turbine:-1. Turbine blades 2. turbine casing 3. Turbine rotors (disc rotors ,drum rotors)

BLOCK DIAGRAM OF STEAM POWER PLANT

HP TURBINE

Steam parametersParametersUnitSub critical500 mwSuper critical

Ms pressureBar170247

Inlet temp0c537565

Outlet pressureBar4554

Outlet temp0c340.1336.7

No. Of stages 1719

Inner CasingInletttOuter Casing-Barrel typeExhaustShaft Seal FrontShaft Seal-RearBarrel type casing:-The HP casing is designed as a barrel type casing without axial joint. An axially split guide blade carrier is arranged in barrel type casing. Because of its rotational symmetry the barrel type casing also remain constant in shape and leak proof during quick changes in temp (ex. On startup and shut down, on load change and under high pressure). The guide blade, too, is almost cylindrical in shape as the horizontal joint flanges are relieved by higher pressure arising outside, and can thus be kept small. For this reason, turbines with barrel type casing are suitable for quick startup and loading.

Seals: - The u shaped seal ring, that is fixed against the axial sealing surface by the steam pressure and I shaped sealing ring that allow axial displacement of the guide blade carrier, seal the space between guide blade carrier and barrel type casing from the adjacent spaces. Sealing strips are caulked in to the inner casing and shaft to reduce leakage losses at the blade tips

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Attachment of inner casing: - guide blade carrier is attached in the horizontal and the vertical planes in the barrel type casing so that they can freely expand radially in all direction.

Valves: - the HP turbine is fitted with two initial steam stop and control valve. A stop and control valve with stems arrange in right angle to each other are combined in a common body. The stop valves are spring loaded single seat valves, the control valve also of single seat design having diffuser to reduce pressure losses. The IP turbine is to combined reheat stop and control valve. The reheat stop valve are spring loaded single seat valve the control valve operate in parallel and a fully open in the upper load range. All the valve are actuated by individual oil hydraulic servo motors.Moving and stationary blades: - The hp turbine blade consists of several drum stages. All stages are reaction stages with 50%. The stationary and moving blades of the front stages are provided t routes which also determine the distance between the blades. Their cover plates are machined integral with the blade provides a continuous shroud after inspection. The moving and stationary blades are inserted into appropriately shaped grooves in the shaft or inner casing and are bottom caulked with caulking material. The insertion slot in the shaft is closed by a locking blade which is fixed either by taper pins or grub screw. Special end blades which locked with a horizontal joint are used at the horizontal joints of the inner casing. Grub screw which are inserted from the joint into the material secure the stationary blade in the grooves.The rear stages have stationary blades with hook type root which are secured in annular grooves in the inner casing by filler piece. The shroud of these stationary blades are riveted on the blades in sections. The moving blade of these stages have the same design as those of the front stages.

IP TURBINE

IP turbine steam parametersParametersUnitSub critical500 mwSuper critical660 mw

Inlet pressureBar4054

Inlet temp0c537543

Outlet pressureBar7.1286.08

Out let temp0c289.3281.9

No. Of stagesSymmetrical2*(7+5)Non-symmetrical(7+9),(12+4)

Double shell construction (casing):-The casing of IP turbine is split horizontally and is of double shell construction the double flow inner casing is supported in the outer casing. Steam from hp turbine after reheating enters the inner casing from above and below through two inlet nozzle flanged to the mid-section of the outer casing. This arrangement provides opposed flow in the two blade section and compensates axial thrust. The center flow prevents the steam temp from affecting the support bracket and bearing sections.Attachment of inner casing:-Due to different temp. Of inner casing relative to the outer casing, the inner casing is attached to the outer casing in such a manner as to be free to expand axially from a fix point and radially in all the directions, while maintaining the concentricity of the inner casing relative to the designed to avoid any restrictions due to thermal expansion.

LP TURBINE

LP- turbine steam parameters

ParametersUnitSub critical500 mwSuper critical660 mw

Inlet pressureBar7.0055.97

Inlet temp0c291.9282.1

Outlet pressureBar0.10270.1047

Outlet temp0c46.35550

No. Of stages2*(2+4)2*(1+2+2)

LP casing:-Construction: - the lp turbine casing consist of a double flow unit and has a triple shell welded casing. The outer casing consist of the front and rear walls, the two lateral longitudinal support beams and the upper parts. The front and rear walls, as well as the connection areas of the upper part are reinforced by means of a circular box beams. The outer casing is supported by the ends of the longitudinal beams on the base plate of the foundation.Steam admission:-Steam admitted to the lp turbine from the Ip turbine flow into the inner casing from both sides through steam inlet nozzle before the lp blading. Expansion joints are installed in the steam piping to prevent any undesirable deformation of the casing due to thermal expansion of the steam piping.Inner casing:-The double flow inner casing which is of double shell construction, consist of the outer shell and the inner shell. The inner shell is attached in the outer shell with provision for free thermal movement. Stationary blading is carried by the inner shell.

STEAM FLOW THROUGH STEAM TURBINE

TURBINE BLADESBasically the design of blades is classified according to the stages of turbine. The size of LP TURBINE BLADES is generally greater than that of HP turbine blades. At the first T1, T2, T3 & T4 kinds of blades were used, these were 2nd generation blades. Then it was replaced by TX, 3DS (for HP TURBINE) & F shaped blades. The most modern blades are F & Z shaped blades.

There are following types of blades used in various stages of turbine:1:First generation blades :T2 profile blades are first generation blades. These are used since 1970. These arecylindrical profile blades having low stage efficiency.Stage efficiency: It is the measure of effectiveness of energy supplied to the blade by the steam.

2:Second generation blades :a. T4 profile blades: These are cylindrical profile blades used since late 1980. T4 profile give 1% gain in stage efficiency over t2 profile blades.b. Tx profile blades:Cylindrical profile blades developed in 1990.Reduces profile losses.0.2% gain in stage efficiency over t4 profile blades. Used in middle stages of HP and IP turbine and initial stages of IP Turbine.c. 3ds blades :Reduces secondary flow losses.0.5 1.0% gain in stage efficiency over TX profile blades. Used in initial stage of HP And IP turbines.d. F- blades:Reduces indirect flow losses0.5 1.0% gain in stage efficiency over tx profile bladesRear stages of h.p. And i.p turbines and middle stages of l.p. Turbinee. Fir tree blades:These blades are used in last stages of LP turbine.Manufactured by drop forging in Germany.Twisted and varying profile blades.

BLADING MATERIALS

Among the different materials typically used for blading are 403 stainless steel, 422 stainless steel, A-286, and Haynes Stellite Alloy Number 31 and titanium alloy. The 403 stainless steel is essentially the industrys standard blade material and, on impulse steam turbines, it is probably found on over 90 percent of all the stages. It is used because of its high yield strength, endurance limit, ductility, toughness, erosion and corrosion resistance, and damping. It is used within a Brinell hardness range of 207 to 248 to maximize its damping and corrosion resistance. The 422 stainless steel material is applied only on high temperature stages (between 700 and 900F or 371 and 482C), where its higher yield, endurance, creep and rupture strengths are needed. The A-286 material is a nickel-based super alloy that is generally used in hot gas expanders with stage temperatures between 900 and 1150F (482 and 621C). The Haynes Stellite Alloy Number 31 is a cobalt-based super alloy and is used on jet expanders when precision cast blades are needed. The Haynes Stellite Number 31 is used at stage temperatures between 900 and 1200F (482 and 649C). Another blade material is titanium. Its high strength, low density, and good erosion resistance make it a good candidate for high speed or long-last stage blading.

OPERATIONS PERFORMED ON BLADESSome of the important operations performed on blade manufacturing are:- Milling Blank Cutting Grinding of both the surfaces Cutting Root milling

MACHINING OF BLADES Machining of blades is done with the help of Lathe & CNC machines. Some of the machines are:- Centre lathe machine Vertical Boring machine Vertical Milling machine CNC lathe machine

ROTOR MATERIALSThe required material properties for the hot IP section with smaller blades and the cold LP section with large centrifugal forces are completely different. Therefore, only a welded rotor design enables the use of optimal materials for both the hot IP section and the cold LP section the combination of two materials for the rotor yields an optimum of mechanical properties over a wide reheat temperature range: up to 565C 2%-Cr-steel is utilized for the IP rotor block and the inner casing. Up to 600C, the rotor and inner casing material is substituted by a 10%-Cr-steel. The LP rotor block consists of a 3.5%-Ni-steel. The rotor welding seam is positioned behind the LP front stages. This offers the advantage to implement a cost effective welding seam at the low diameter of the IP drum.

Bearings and lubrication Two types of bearings are used to support and locate the rotors ofSteam turbines:Journal bearings are used to support the weight of the turbine rotors. AJournal bearing consists of two half-cylinders that enclose the shaft andAre internally lined with Babbit, a metal alloy usually consisting of tin,Copper and antimony; and thrust bearings axially locate the turbineRotors. A thrust bearing is made up of a series of Babbit lined pads thatRun against a locating disk attached to the turbine rotor.High-pressure oil is injected into the bearings to provide lubrication.The oil is carefully filtered to remove solid particles. Specially designedCentrifuges remove any water from the oil.

Over speed and balancing tunnelThere are two operations performed at OSBT:1: Balancing of rotor: In a rotating rotor centrifugal forces remain balanced as long as the Centre of mass of the rotor lies on the axis of the shaft. When the c.m. Does not lie on the axis of the shaft or there is eccentricity, an unbalance force is produced which is very common in turbine rotors.These forces exerted on the frame by the moving machine members are time varying, impart vibratory motion to the frame and produces noise.For balancing, we insert balance weight (it is of known mass) in dovetail groove. Dovetail is a groove which is cut after last stage of turbine blading. Static balancing is done up to 400 rpm. Dynamic balancing and vibration control are done at speed higher than 400 rpm. Balancing test is done in vacuum chamber which is maintained at maximum pressure of 1 torr. Vacuum chamber is required to reduce the power lost because of high air resistance.

2. Over speed testing of rotor: For over speed testing, rotor is subjected to over speed of 25% of operating speed. In balancing test dc motor is use to run the turbine at standard rpm.

CONCLUSIONGone through rigorous one month training under the guidance of capable engineers and workers of BHEL Haridwar in Block-3 TURBINE MANUFACTURING headed by Senior Engineer of TUM department JAIKESH SINGH situated in Ranipur, Haridwar, Uttarakhand.

The training was specified under the Turbine Manufacturing Department. Working under the department I came to know about the basic grinding, scaling and machining processes which was shown on heavy to medium machines. Duty lathes were planted in the same line where the specified work was undertaken.

The training brought to my knowledge the various machining and fabrication processes went not only in the manufacturing of blades but other parts of the turbine.8 | Page