INDUSTRIAL TRAINING REPORT ON MACHINING OF CRITICAL ASSEMBLIES OF STEAM TURBINE

(JUNE – JULY 2015)

A Report

submitted is partial fulfillment of the

requirement for the award of the Degree of

BACHELOR OF TECHNOLOGYIN

MECHANICAL ENGINEERINGBY

MOHIT MAMGAIN (121190104029)

Department of Mechanical Engineering

SEEMANT INSTITUTE OF TECHNOLOGY

PITTHORAGARH (U.K.)

2012-2016

DECLARATION CERTIFICATE

This is to certify that the work presented in the project entitled “PROJECT REPORT ON MACHINING OF CRITICAL ASSEMBLIES OF STEAM TURBINE” in partial fulfilment of the requirement for the award of degree of Bachelor in Technology in Mechanical Engineering from Seemant institute of Technology, Pitthoragarh is an authentic work carried out under my supervision and guidance.

To the best of my knowledge , the content of this project does not form a basis for the award of any previous degree to anyone else.

Date :

(Mr. DEVNIDHI BISHT)

Dept. of Mechanical Engineering

Seemant Institute of Technology

Pithoragarh

Head Director

Dept. of Mechanical Engineering Seemant Institute of Technology Technology

Seemant Institute of Technology Pithoragarh

Pithoragarh

ACKNOWLEDGEMENT

“An engineer with only theoretical knowledge is not a complete Engineer. Practical knowledge is very important to develop and apply engineering skills”. It gives me a great pleasure to have an opportunity to acknowledge and to express gratitude to those who were associated with me during my training at BHEL.I am very grateful to Mr. AJMANI ROHIT for providing me with an opportunity to undergo training under his able guidance.Furthermore, special thanks to Mr. Raj Singh for his help and support in Haridwar. Last, but not the least, I would also like to acknowledge the support of my college friends, who pursued their training with me. We shared some unforgettable moments together.I express my sincere thanks and gratitude to BHEL authorities for allowing me to undergo the training in this prestigious organization. I will always remain indebted to them for their constant interest and excellent guidance in my training work, moreover for providing me with an opportunity to work and gain experience.

THANK YOU

ABSTRACT

In the era of Mechanical Engineering, Turbine, A Prime Mover ( Which uses the Raw Energy ofa substance and converts it to Mechanical Energy) is a well known Machine most useful in thethe field of Power Generation. This Mechanical energy is used in running an Electric Generatorwhich is directly coupled to the shaft of turbine. From this Electric Generator, we get electricPower which can be transmitted over long distances by means of transmission lines andtransmission towers.In my Industrial Training in B.H.E.L., Haridwar I go through all sections in TurbineManufacturing. First management team told me about the history of industry, Area, Capacity,Machines installed & Facilities in the Industry.After that they told about the Steam Turbine its types , parts like Blades, Casing, Rotor etc. Thenthey told full explanation of constructional features and procedure along with equipement used.Before telling about the machines used in Manufacturing of Blade, they told about the safetyprecautions, Step by Step arrangement of machines in the block with a well defined properformat. They also told the material of blade for a particular desire, types of Blades, Operationsperformed on Blades, their New Blade Shop less with Advance Technology like CNC ShapingMachine.I would like to express my deep sense of Gratitude and thanks to MR. AJMANI ROHITin charge of training in Turbine Block in B.H.E.L., Haridwar. Without the wise counsel and ableguidance, it would have been impossible to complete the report in this manner. Finally, I amindebted to all who so ever have contributed in this report and friendly stay at Bharat HeavyElectricals Limited (BHEL).

INDEX

SR NO TOPIC PAGE NO.

1. INTRODUCTION

2. BHEL - AN OVERVEIW

3. STEAM TURBINE

4. BHEL HARIDWAR

5. TURBINE PARTS

6. MANUFACTURING PROCESS

7. PLANT LAYOUT

8. CLASSIFICATION OF BLOCK 3

9. CONCLUSION

10.

FIGURE INDEX

S.NO. FIGURE PAGE1. Steam turbine

2. Turbine blades

3. Turbine casing

4. Turbine rotors

5. Furnace

6. Prepared mould

7. Boring process

8. Layout diagram

9. Over speed & vacuum balancing tunnel (OSVBT)

10. Steam turbine casing and rotors in assembly area

1. INTRODUCTIONBHEL is the largest engineering and manufacturing enterprise in India in the energy related infrastructure sector today. BHEL was established more than 40 years ago when its first plant was setup in Bhopal ushering in the indigenous Heavy Electrical Equipment Industry in India a dream which has been more than realized with a well recognized track record of performance it has been earning profits continuously since1971-72.

BHEL caters to core sectors of the Indian Economy viz., Power Generation's & Transmission, Industry, Transportation, Telecommunication, Renewable Energy, Defense, etc. The wide network of BHEL's 14 manufacturing division, four power Sector regional centers, over 150 project sites, eight service centers 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. BHEL has already attained ISO 9000 certification for quality management, and ISO 14001certification for environment management. The company’s inherent potential coupled with its strong performance make this one of the “NAVRATNAS”, which is supported by the government in their endeavor to become future global players.

2. B.H.E.L- An Overview

BHEL 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 Uttaranchal. 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 andmanufactures 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.

BHEL is an integrated power plant equipment manufacturer and one of the largest engineering and manufacturing companies in India in terms of turnover. BHEL was established in 1964, ushering in the indigenous Heavy Electrical Equipment industry in India - a dream that has been more than realized with a well-recognized track record of performance. The company has been earning profits continuously since 1971-72 and paying dividends since 1976-77 .BHEL is engaged in the design, engineering, manufacture,

construction ,testing, commissioning and servicing of a wide range of products and services for the core sectors of the economy, viz. Power, Transmission, Industry, Transportation, Renewable Energy, Oil & Gas and Defence. BHEL has 15 manufacturing divisions, two repair units, four regional offices, eight service centres, eight overseas offices and15 regional centres and currently operate at more than 150 project sites across India and abroad. BHEL places strong emphasis on innovation and creative development of new technologies. Our research and development (R&D) efforts are aimed not only at improving the performance and efficiency of our existing products, but also at using state-of-the-art technologies and processes to develop new products. This enables us to have a strong customer orientation, to be sensitive to their needs and respond quickly to the changes in the market.

BHEL has a share of around 59% in India's total installed generating capacity contributing 69% (approx.) to the total power generated fromutility sets (excluding non-conventional capacity) as of March 31, 2012. We have been exporting our power and industry segment products and services for approximately 40 years. We have exported our products and services to more than 70 countries. We had cumulatively installed capacity of over 8,500 MW outside of India in 21 countries, including Malaysia, Iraq, the UAE, Egypt and New Zealand. Our physical exports range from turnkey projects to after sales services.

3. STEAM TURBINE

FIGURE 1A 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 primarily because of its greater thermal efficiency and higher power-to-weight ratio. Because the turbine generates rotary motion, itis particularly suited to be used to drive an electrical generator – about80% of all electricity generation in the world is by use of steamturbines. 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.

3.1. ADVANTAGES

1. Ability to utilize high pressure and high temperature steam.2. High efficiency.3. High rotational speed.4. High capacity/weight ratio.5. Smooth, nearly vibration-free operation.6. No internal lubrication.7. Oil free exhausts steam.

3.2. DISADVANTAGES

For slow speed application reduction gears are required. The steam turbine cannot be made reversible. The efficiency of small simple steam turbines is poor.

4. BHEL HARIDWAR

4.1. LOCATION

It is situated in the foot hills of Shivalik range in Haridwar. The main administrative building is at a distance of about 8 km from Haridwar.

4.2. ADDRESS

Bharat Heavy Electrical Limited (BHEL) .

Ranipur, Haridwar PIN- 249403

4.3. UNITS

There are two units in BHEL Haridwar as followed:

1) Heavy Electrical Equipment Plant (HEEP)

The core business of HEEP includes design and manufacture oflarge stesm and gas turbines, turbo generators, generators, large AC/DC motors and so on.

2) Central Foundry Forge Plant (CFFP) CFFP is engaged in manufacture of steel castings up to 50 tons per piece weight and steel forgings up to 55 tons per piece.

5. TURBINE PARTS5.1. TURBINE BLADES1. Cylindrical reaction blades for HP, IP and LP Turbines2. 3-DS blades, in initial stages of HP and IP Turbine, to reduce secondary losses.3. Twisted blade with integral shroud, in last stages of HP, IP and initial stages of LP turbines, to reduce profile and Tip leakage losses

figure 24. Free standing LP moving blades Tip sections with supersonic design.5. Fir-tree root6. Flame hardening of the leading edge7. Banana type hollow guide blade8. Suction slits for moisture removal

5.2. TURBINE CASINGCasings or cylinders are of the horizontal split type. This is not ideal, as the heavy flanges of thejoints are slow to follow the temperature changes of the cylinder walls. However, for assemblingand inspection purposes there is no other solutionThe casing is heavy in order to withstand the

Figure 3high pressures and temperatures. It is general practice to let the thickness of walls and flangesdecrease from inlet- to exhaust-end. The casing joints are made steam tight, without the use ofgaskets, by matching the flange faces very exactly and very smoothly. The bolt holes in theflanges are drilled for smoothly fitting bolts, but dowel pins are often added to secure exactalignment of the flange joint. Double casings are used for very high steam pressures. The highpressure is applied to the inner casing, which is open at the exhaust end, letting the turbineexhaust to the outer casings.

5.3. TURBINE ROTORSThe design of a turbine rotor depends on the operating principle of the turbine. The impulseturbine with pressure drop across the stationary blades must have seals between stationary bladesand the rotor. The smaller the sealing area, the smaller the leakage; therefore the stationary

blades are mounted in diaphragms with labyrinth seals around thes haft. This constructionrequires a disc rotor. Basically there are two types of rotor:

5.3.1. DISC ROTORSAll larger disc rotors are now machined out of a solid forging of nickel steel; this should give thestrongest rotor and a fully balanced rotor. It is rather expensive, as the weight of the final rotor isapproximately 50% of the initial forging. Older or smaller disc rotors have shaft and discs madein separate pieces with the discs shrunk on the shaft. The bore of the discs is made 0.1% smallerin diameter than the shaft. The discs are then heated until they easily are slid along the shaft andlocated in the correct position on the shaft and shaft key. A small clearance between the discsprevents thermal stress in the shaft.

Figure 4

5.3.2.DRUM ROTORSThe first reaction turbines had solid forged drum rotors. They were strong, generally wellbalanced as they were machined over the total surface. With the increasing size of turbines thesolid rotors got too heavy pieces. For good balance the drum must be machined both outside andinside and the drum must be open at one end. The second part of the rotor is the drum end coverwith shaft.

5.4. BLADING MATERIALSAmong the different materials typically used for blading are 403 stainless steel, 422 stainlesssteel, A-286, and Haynes Satellites Alloy Number 31 and titanium alloy. The403 stainless steel isessentially the industry’s standard blade material and, on impulse steam turbines, it is probablyfound on over 90 percent of all the stages. It is used because of its high yield strength, endurancelimit, ductility, toughness, erosion and corrosion resistance, and damping. It is used within aBrinell hardness range of 207 to 248 to maximize its damping and corrosion resistance. The 422stainless steel material is applied only on high temperature stages (between 700 and 900°F or

371 and 482°C), 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 withstage temperatures between 900 and 1150°F (482 and 621°C). The Haynes Satellites AlloyNumber 31 is a cobalt-based super alloy and is used on jet expanders when precision cast bladesare needed. The Haynes Satellite Number 31 is used at stage temperatures between 900 and1200°F (482 and 649°C). Another blade material is titanium. Its high strength, low density, andgood erosion resistance make it a good candidate for high speed or long-last stage blading.

6. MANUFACTURING PROCESS

6.1. INTRODUCTION

Manufacturing process is that part of the production process which is directly concerned with thechange of form or dimensions of the part being produced. It does not include the transportation,handling or storage of parts, as they are not directly concerned with the changes into the form ordimensions of the part produced. Manufacturing is the backbone of any industrialized nation.Manufacturing and technical staff in industry must know the various manufacturing processes,materials being processed, tools and equipments for manufacturing different components orproducts with optimal process plan using proper precautions and specified safety rules to avoidaccidents. Beside above, all kinds of the future engineers must know the basic requirements ofworkshop activities in term of man, machine, material, methods, money and other infrastructurefacilities needed to be positioned properly for optimal shop layouts or plant layout and othersupport services effectively adjusted or located in the industry or plant within a well plannedmanufacturing organization. Today’s competitive manufacturing era of high industrialdevelopment and research, is being called the age of mechanization, automation and computerintegrated manufacturing. Due to new researches in the manufacturing field, the advancementhas come to this extent that every different aspect of this technology has become a full-fledgedfundamental and advanced study in itself. This has led to introduction of optimized design andmanufacturing of new products. New developments in manufacturing areas are deciding totransfer more skill to the machines for considerably reduction of manual labor.

6.2. CLASSIFICATION OF MANUFACTURING PROCESSES

For producing of products materials are needed. It is therefore important to know thecharacteristics of the available engineering materials. Raw materials used manufacturing ofproducts, tools, machines and equipments in factories or industries are for providing commercialcastings, called ingots. Such ingots are then processed in rolling mills to obtain market form ofmaterial supply in form of bloom, billets, slabs and rods. These forms of material supply arefurther subjected to various manufacturing processes for getting usable metal products ofdifferent shapes and sizes in various manufacturing shops. All these processes used inmanufacturing concern for changing the ingots into usable products may be classified into sixmajor groups as1. Primary shaping processes2. Secondary machining processes3. Metal forming processes

4. Joining processes5. Surface finishing processes and6. Processes effecting change in properties

6.2.1 PRIMARY SHAPING PROCESSES

Primary shaping processes are manufacturing of a product from an amorphous material. Someprocesses produces finish products or articles into its usual form whereas others do not, andrequire further working to finish component to the desired shape and size. The parts producedthrough these processes may or may not require to undergo further operations. Some of theimportant primary shaping processes are:1. Casting2. Powder metallurgy3. Plastic technology4. Gas cutting5. Bending and6. Forging

Figure 5

Figure 6

6.2.2. SECONDARY OR MACHINING PROCESSESAs large number of components require further processing after the primary processes. Thesecomponents are subjected to one or more number of machining operations in machine shops, toobtain the desired shape and dimensional accuracy on flat and cylindrical jobs. Thus, the jobsundergoing these operations are the roughly finished products received through primary shapingprocesses. The process of removing the undesired or unwanted material from the work-piece orjob or component to produce a required shape using a cutting tool is known as machining. Thiscan be done by a manual process or by using a machine called machine tool. In many cases these operations are performed on rods, bars and flat surfaces in machine shops.These secondary processes are mainly required for achieving dimensional accuracy and a veryhigh degree of surface finish. The secondary processes require the use of one or more machinetools, various single or multi-point cutting tools (cutters), jobholding devices, marking andmeasuring instruments, testing devices and gauges etc. forgetting desired dimensional controland required degree of surface finish on the work-pieces. The example of parts produced bymachining processes includes hand tools machine tools instruments, automobile parts, nuts, boltsand gears etc. Lot of material is wasted as scrap in the secondary or machining process. Some ofthe common secondary or machining processes are:1. Turning 8. Threading2. Knurling 9. Milling3. Drilling 10. Blanking4. Boring 11. Planning5. Shaping 12. Gear Cutting6. Grinding 13. Thread cutting and7. Unconventional machining processes namely machining with Computer Numerical

Control (CNC) machine tool

Figure 7

7. BLOCK 3 LAY-OUT

Figure 8

8. CLASSIFICATION OF BLOCK 3

8.1. BAY-1 IS FURTHER DIVIDED INTO THREE PARTS

8.1.1. HMSIn this shop heavy machine work is done with the help of different NC &CNC machinessuch as center lathes, vertical and horizontal boring & milling machines. Asia’s largest verticalboring machine is installed here and CNC horizontal boring milling machines from Skoda ofCzechoslovakia.

8.2.2. Assembly Section In this section assembly of turbines are done. Blades of turbine are1st assemble onthe rotor & after it this rotor is transported to balancing tunnel where the balancing is done. Afterbalancing 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 B.H.E.L.

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 .Ina large tunnel, Vacuum of 2 torr is created with the help of pumps & after that rotor is placed onpedestal and rotted with speed of 2500-4500 rpm. After it in a computer control room the axis ofrotation of rotor is seen with help of computer & then balance the rotor by inserting the smallbalancing weight in the grooves cut on rotor.

Figure 9For balancing and over speed testing of rotors up to 320 tons in weight, 1800 mm in length and6900 mm diameter under vacuum conditions of 1 Torr.

8.2. BAY –2 IS DIVIDED IN TO 2 PARTS:

8.2.1. HMSIn this shop several components of steam turbine like LP, HP & IP rotors, Internal & external

casing are manufactured with the help of different operations carried out through different NC &CNC machines like grinding, drilling, vertical & horizontal milling and boring machines, centerlathes, planer, Kopp milling machine.

8.2.2. Assembly SectionIn this section assembly of steam turbines up to 1000 MWIs assembled. 1st moving blades areinserted in the grooves cut on circumferences of rotor, then rotor is balanced in balancing tunnelin bay-1.After is done in which guide blades are assembled inside the internal casing & thenrotor is fitted inside this casing. After it this internal casing with rotor is inserted into theexternal.

8.3 . BAY 3 IS DIVIDED INTO 3 PARTS:

8.3.1. Bearing SectionIn this section Journal bearings are manufactured which are used in turbines to overcomethe vibration & rolling friction by providing the proper lubrication.

8.3.2. Turning SectionIn this section small lathe machines, milling & boring machines, grinding machines &drilling machines are installed. In this section small jobs are manufactured like rings, studs, disksetc.

8.3.3. Governing SectionIn this section governors are manufactured. These governors are used in turbines forcontrolling the speed of rotor within the certain limits. 1st all components of governor are madeby different operations then these all parts are treated in heat treatment shop for providing thehardness. Then these all components are assembled into casing. There are more than 1000components of Governor.

8.4. BAY-4 IS DIVIDED INTO 3 PARTS:

8.4.1. TBM (Turbine Blade Manufacturing) ShopIn this shop solid blade of both steam & gas turbine are manufactured. SeveralCNC & NC machines are installed here such as Copying machine, Grinding machine, Rhomboidmilling machine, Duplex milling machine, T- root machine center, Horizontal tooling center,Vertical & horizontal boring machine etc.

Figure 10

8.4.2. Turning SectionSame as the turning section in Bay-3, there are several small Machine like lathesmachines, milling, boring, grinding machines etc.

Figure 118.4.3. Heat Treatment ShopIn this shop there are several tests performed for checking the Hardness of differentcomponents. Tests performed are Sereliting, Nitriding, DP Test.

9. CONCLUSIONGone through 1 month training under the guidance of capable engineers and workers ofBHEL Haridwar in Block-3 “TURBINE MANUFACTURING” headed by Senior Engineer ofDepartment Mr . Ajmani Rohit situated in Ranipur, Haridwar,(Uttarakhand).The training was specified under the Turbine Manufacturing Department. Working under thedepartment I came to know about the basic grinding, scaling and machining processes which wasshown on heavy to medium machines.