INDUSTRIAL TRAINING REPORT
(JUNE – JULY 2014)
Submitted in partial fulfilment of the requirements
Of the degree of
Bachelor of Technology
In
Mechanical Engineering
By
(ABHISHEK CHAUDHARY)
(1101201085)
(School of Civil and Mechanical Engineering)
GALGOTIAS UNIVERSITY
GREATER NOIDA
2011-2015
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. JAIKESH SINGH 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 of
a substance and converts it to Mechanical Energy) is a well known Machine most useful in the
the field of Power Generation. This Mechanical energy is used in running an Electric Generator
which is directly coupled to the shaft of turbine. From this Electric Generator, we get electric
Power which can be transmitted over long distances by means of transmission lines and
transmission towers.
In my Industrial Training in B.H.E.L., Haridwar I go through all sections in Turbine
Manufacturing. 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. Then
they 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 safety
precautions, Step by Step arrangement of machines in the block with a well defined proper
format. They also told the material of blade for a particular desire, types of Blades, Operations
performed on Blades, their New Blade Shop less with Advance Technology like CNC Shaping
Machine.
I would like to express my deep sense of Gratitude and thanks to MR. JAIKESH SINGH
in charge of training in Turbine Block in B.H.E.L., Haridwar. Without the wise counsel and able
guidance, it would have been impossible to complete the report in this manner. Finally, I am
indebted to all who so ever have contributed in this report and friendly stay at Bharat Heavy
Electricals Limited (BHEL).
INDEX
ACKNOWLEDGEMENT
ABSTRACT
SR NO TOPIC PAGE NO.
1. INTERODUCTION
2. BHEL-AN OVERVEIW
3. STEAM TURBINE
4. TYPES OF STEAM TURBINE
5. BHEL UNITS
6. BHEL HARIDWAR
7. TURBINE PARTS
8. MANUFACTURING PROCESS
9. BLADE SHOP
10. CONCLUSION
INTRODUCTION BHEL 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
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 theBHEL, 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 and manufactures turbo generators, AC and DC motors, gas turbines and huge steams. The Central Foundry Forge Plant in Haridwar deals withsteel 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. These two units have also earned the ISO - 14001 certificates. Situate in Ranipur near Haridwar, the Bharat Heavy Engineering Limited employs over 8,000 people. BHEL is an integrated power plant equipment manufacturer and oneof 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 and
15 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. The high level of quality & reliability of our products is due to adherence to international standards by acquiring and adapting some of the best technologies from leading companies in the world including General Electric Company, Alstom SA, Siemens AG and Mitsubishi Heavy Industries Ltd., together with technologies developed in our own R&D centres. Most of our manufacturing units and other entities have been accredited to Quality Management Systems (ISO 9001:2008), Environmental Management Systems (ISO 14001:2004) and Occupational Health & Safety Management Systems (OHSAS 18001:2007). 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. BHEL work with a vision of becoming a world-class engineering enterprise, committed to enhancing stakeholder value.
Our greatest strength is our highly skilled and committed workforce of over 49,000 employees. Every employee is given an equal opportunity to develop himself and grow in his career. Continuous training and retraining, career planning, a positive work culture and participative style of management - all these have engendered development of a committed and motivated workforce setting new benchmarks in terms of productivity, quality and responsiveness.
STEAM TURBINE
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 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. ADVANTAGES:-
ed.
-free operation.
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.
STEAM TURBINES THE MAINSTAY OF BHEL:-
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 600ºC.
ting of modules suitable for a range of output and steam parameters.
ate turbine
blocks can be selected. Types 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 Steam turbines are made in a variety of sizes ranging from small 1 hp (0.75 kW) units (rare) used as mechanical drives for pumps, compressors and other shaft driven equipment, to 2,000,000 hp (1,500,000 kW) turbines used to generate electricity. There are several classifications for modern steam turbines. Steam Supply and Exhaust Conditions These types include condensing, non-condensing, reheat, extraction and induction. Non-condensing 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.
Casing or Shaft Arrangements 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. Turbine Efficiency To maximize turbine efficiency, the steam is expanded, generating work, in a number of stages. These stages are characterized by how the energy is extracted from them and are known as impulse or reaction turbines. Most modern steam turbines are a combination of the reaction and impulse design. Typically, higher pressure sections are impulse type and lower pressure stages are reaction type. Impulse Turbines An impulse turbine has fixed nozzles that orient the steam flow into high speed jets. These jets contain significant kinetic energy, which the rotor blades, shaped like buckets, convert into shaft rotation as the steam jet changes direction. A pressure drop occurs across only the stationary blades, with a net increase in steam velocity across the stage.
Reaction Turbines In the reaction turbine, the rotor blades themselves are arranged to form convergent nozzles. This type of turbine makes use of the reaction force produced as the steam accelerates through the nozzles formed by the rotor. Steam is directed onto the rotor by the fixed vanes of the stator. It leaves the stator as a jet that fills the entire circumference of the rotor. The steam then changes direction and increases its speed relative to the speed of the blades. A pressure drop occurs across both the stator and the rotor, with steam accelerating through the stator and decelerating through the
rotor, with no net change in steam velocity across the stage but with a decrease in both pressure and temperature.
DIFFERENCES BETWEEN IMPULSE AND REACTION TURBINE
BHEL HARIDWAR
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.
2. ADDRESS
Bharat Heavy Electrical Limited (BHEL)
Ranipur, Haridwar PIN- 249403
3. AREA
BHEL Haridwar consists of two manufacturing units, namely Heavy Electrical Equipment Plant( HEEP) and Central Foundry Forge Plant (CFFP), having area
HEEP area:- 8.45 sq km
CFFP area:- 1.0 sq km
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.
4. UNITS
There are two units in BHEL Haridwar as followed:
1) Heavy Electrical Equipment Plant (HEEP)
2) Central Foundry Forge Plant (CFFP)
TURBINE PARTS
1 TURBINE BLADES
Cylindrical reaction blades for HP, IP and LP Turbines
3-DS blades, in initial stages of HP and IP Turbine, to reduce secondary losses.
Twisted blade with integral shroud, in last stages of HP, IP and initial stages of LP turbines,
to reduce profile and Tip leakage losses
o Free standing LP moving blades Tip sections with supersonic design.
o Fir-tree root
o Flame hardening of the leading edge
o Banana type hollow guide blade
o Tapered and forward leaning for optimized mass flow distribution
o Suction slits for moisture removal
2 TURBINE CASING Casings or cylinders are of the horizontal split type. This is not ideal, as the heavy flanges of the
joints are slow to follow the temperature changes of the cylinder walls. However, for assembling
and inspection purposes there is no other solution. The casing is heavy in order to withstand the
high pressures and temperatures. It is general practice to let the thickness of walls and flanges
decrease from inlet- to exhaust-end. The casing joints are made steam tight, without the use of
gaskets, by matching the flange faces very exactly and very smoothly. The bolt holes in the
flanges are drilled for smoothly fitting bolts, but dowel pins are often added to secure exact
alignment of the flange joint. Double casings are used for very high steam pressures. The high
pressure is applied to the inner casing, which is open at the exhaust end, letting the turbine
exhaust to the outer casings.
3 TURBINE ROTORS The design of a turbine rotor depends on the operating principle of the turbine. The impulse
turbine with pressure drop across the stationary blades must have seals between stationary blades
and 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 construction
requires a disc rotor. Basically there are two types of rotor:
DISC ROTORS
All larger disc rotors are now machined out of a solid forging of nickel steel; this should give the
strongest rotor and a fully balanced rotor. It is rather expensive, as the weight of the final rotor is
approximately 50% of the initial forging. Older or smaller disc rotors have shaft and discs made
in separate pieces with the discs shrunk on the shaft. The bore of the discs is made 0.1% smaller
in diameter than the shaft. The discs are then heated until they easily are slid along the shaft and
located in the correct position on the shaft and shaft key. A small clearance between the discs
prevents thermal stress in the shaft.
DRUM ROTORS
The first reaction turbines had solid forged drum rotors. They were strong, generally well
balanced as they were machined over the total surface. With the increasing size of turbines the
solid rotors got too heavy pieces. For good balance the drum must be machined both outside and
inside and the drum must be open at one end. The second part of the rotor is the drum end cover
with shaft.
1. CONSTRUCTIONAL FEATURES OF A BLADE The blade can be divided into 3 parts:
The profile, which converts the thermal energy of steam into kinetic energy, with a
certain efficiency depending upon the profile shape.
The root, which fixes the blade to the turbine rotor, giving a proper anchor to the blade,
and transmitting the kinetic energy of the blade to the rotor.
The damping element, which reduces the vibrations which necessarily occur in the blades
due to the steam flowing through the blades. These damping elements may be integral
with blades, or they may be separate elements mounted between the blades. Each of these
elements will be separately dealt with in the following sections.
1.1 H.P. BLADE PROFILES In order to understand the further explanation, a familiarity of the terminology used is required.
The following terminology is used in the subsequent sections.
If circles are drawn tangential to the suction side and pressure side profiles of a blade, and their
centers are joined by a curve, this curve is called the camber line. This camber line intersects the
profile at two points A and B. The line joining these points is called chord, and the length of this
line is called the chord length. A line which is tangential to the inlet and outlet edges is called the
bitangent line. The angle which this line makes with the circumferential direction is called the
setting angle. Pitch of a blade is the circumferential distance between any point on the profile
and an identical point on the next blade.
HIGH PRESSURE BLADE AIRFOIL PROFILE
1.2 CLASSIFICATION OF PROFILES There are two basic types of profiles - Impulse and Reaction. In the impulse type of profiles, the
entire heat drop of the stage occurs only in the stationary blades. In the reaction type of blades,
the heat drop of the stage is distributed almost equally between the guide and moving blades.
Though the theoretical impulse blades have zero pressure drop in the moving blades, practically,
for the flow to take place across the moving blades, there must be a small pressure drop across
the moving blades also. Therefore, the impulse stages in practice have a small degree of reaction.
These stages are therefore more accurately, though less widely, described as low-reaction stages.
The presently used reaction profiles are more efficient than the impulse profiles at part loads.
This is because of the more rounded inlet edge for reaction profiles. Due to this, even if the inlet
angle of the steam is not tangential to the pressure-side profile of the blade, the losses are low.
However, the impulse profiles have one advantage. The impulse profiles can take a large heat
drop across a single stage, and the same heat drop would require a greater number of stages if
reaction profiles are used, thereby increasing the turbine length. The Steam turbines use the
impulse profiles for the control stage (1st stage), and the reaction profiles for subsequent stages.
There are four reasons for using impulse profile for the first stage:
a) Most of the turbines are partial arc admission turbines. If the first stage is are action stage, the
lower half of the moving blades do not have any inlet steam, and would ventilate. Therefore,
most of the stage heat drop should occur in the guide blades.
b) The heat drop across the first stage should be high, so that the wheel chamber of the outer
casing is not exposed to the high inlet parameters. In case of -4turbines, the inner casing parting
plane strength becomes the limitation, and therefore requires a large heat drop across the 1st
stage.
c) Nozzle control gives better efficiency at part loads than throttle control.
d) The number of stages in the turbine should not be too high, as this will increase the length of
the turbine.
There are exceptions to the rule. Turbines used for CCPs, and BFP drive turbines do not have a
control stage. They are throttle-governed machines. Such designs are used when the inlet
pressure slides. Such machines only have reaction stages. However, the inlet passages of such
turbines must be so designed that the inlet steam to the first reaction stage is properly mixed, and
occupies the entire 360 degrees. There are also cases of controlled extraction turbines where the
L.P. control stage is an impulse stage. This is either to reduce the number of stages to make the
turbine short, or to increase the part load efficiency by using nozzle control, which minimizes
throttle losses.
1.3 H.P. BLADE ROOTS The root is a part of the blade that fixes the blade to the rotor or stator. Its design depends upon
the centrifugal and steam bending forces of the blade. It should be designed such that the
material in the blade root as well as the rotor / stator claw and any fixing element are in the safe
limits to avoid failure. The roots are T-root and Fork-root. The fork root has a higher
loadcarrying
capacity than the T-root. It was found that machining this T-root with side grip is more
of a problem. It has to be machined by broaching, and the broaching machine available could not
handle the sizes of the root. The typical roots used for the HP moving blades for various steam
turbine applications are
1) T-ROOT
2) T-ROOT WITH SIDE GRIP
2 L.P. BLADE PROFILES The LP blade profiles of moving blades are twisted and tapered. These blades are used when
blade height-to-mean stage diameter ratio (h/Dm) exceeds 0.2.
2.1 LP BLADE ROOTS The roots of LP blades are as follows:
1) 2 Blading : a. The roots of both the LP stages in –2 type of LP Blading are T-roots. 2) 3 Blading: a. The last stage LP blade of HK, SK and LK blades have a fork-root. SK blades
have4-fork roots for all sizes. HK blades have 4-fork roots up to 56 size, where
modified profiles are used. Beyond this size, HK blades have 3 fork roots. LK
blades have 3-forkroots for all sizes. The roots of the LP blades of preceding
stages are of T-roots.
2.2 DYNAMICS IN BLADE The excitation of any blade comes from different sources. They are
Nozzle-passing excitation: As the blades pass the nozzles of the stage, they encounter
flow disturbances due to the pressure variations across the guide blade passage. They
also encounter disturbances due to the wakes and eddies in the flow path. These are
sufficient to cause excitation in the moving blades. The excitation gets repeated at
every pitch of the blade. This is called nozzle-passing frequency excitation. The order
of this frequency =no. of guide blades x speed of the machine. Multiples of this
frequency are considered for checking for resonance.
Excitation due to non-uniformities in guide-blades around the periphery. These can
occur due to manufacturing inaccuracies, like pitch errors, setting angle variations,
inlet and outlet edge variations, etc.
For HP blades, due to the thick and cylindrical cross-sections and short blade heights, the natural
frequencies are very high. Nozzle-passing frequencies are therefore necessarily considered, since
resonance with the lower natural frequencies occurs only with these orders of excitation.
In LP blades, since the blades are thin and long, the natural frequencies are low. The excitation
frequencies to be considered are therefore the first few multiples of speed, since the
nozzlepassing
frequencies only give resonance with very high modes, where the vibration stresses are
low.
The HP moving blades experience relatively low vibration amplitudes due to their thicker
sections and shorter heights. They also have integral shrouds. These shrouds of adjacent blades
butt against each other forming a continuous ring. This ring serves two purposes – it acts as a
steam seal, and it acts as a damper for the vibrations. When vibrations occur, the vibration
energy
is dissipated as friction between shrouds of adjacent blades.
For HP guide blades of Wesel design, the shroud is not integral, but a shroud band is riveted to a
number of guide blades together. The function of this shroud band is mainly to seat the steam. In
some designs HP guide blades may have integral shrouds like moving blades. The primary
function remains steam sealing.
In industrial turbines, in LP blades, the resonant vibrations have high amplitudes due to the thin
sections of the blades, and the large lengths. It may also not always be possible to avoid
resonance at all operating conditions. This is because of two reasons. Firstly, the LP blades are
standardized for certain ranges of speeds, and turbines may be selected to operate anywhere in
the speed range. The entire design range of operating speed of the LP blades cannot be outside
the resonance range. It is, of course, possible to design a new LP blade for each application, but
this involves a lot of design efforts and manufacturing cycle time. However, with the present-day
computer packages and manufacturing methods, it has become feasible to do so. Secondly, the
driven machine may be a variable speed machine like a compressor or a boiler-feed-pump. In
this case also, it is not possible to avoid resonance. In such cases, where it is not possible to
avoid resonance, a damping element is to be used in the LP blades to reduce the dynamic
stresses, so that the blades can operate continuously under resonance also. There may be blades
which are not adequately damped due to manufacturing inaccuracies. The need fora damping
element is therefore eliminated. In case the frequencies of the blades tend towards resonance due
to manufacturing inaccuracies, tuning is to be done on the blades to correct the frequency. This
tuning is done by grinding off material at the tip (which reduces the inertia more than the
stiffness) to increase the frequency, and by grinding off material at the base of the profile (which
reduces the stiffness more than the inertia) to reduce the natural frequency.
The damping in any blade can be of any of the following types:
a) Material damping: This type of damping is because of the inherent damping properties of the
material which makes up the component.
b) Aerodynamic damping: This is due to the damping of the fluid which surrounds the
component in operation.
c) Friction damping: This is due to the rubbing friction between the component under
consideration with any other object.
Out of these damping mechanisms, the material and aerodynamic types of damping are very
small in magnitude. Friction damping is enormous as compared to the other two types of
damping. Because of this reason, the damping elements in blades generally incorporate a feature
by which the vibrational energy is dissipated as frictional heat. The frictional damping has a
particular characteristic. When the frictional force between the rubbing surfaces is very small as
compared to the excitation force, the surfaces slip, resulting in friction damping. However, when
the excitation force is small when compared to the frictional force, the surfaces do not slip,
resulting in locking of the surfaces. This condition gives zero friction damping, and only the
material and aerodynamic damping exists. In a periodically varying excitation force, it may
frequently happen that the force is less than the friction force.
During this phase, the damping is very less. At the same time, due to the locking of the rubbing
surfaces, the overall stiffness increases and the natural frequency shifts drastically away from the
individual value. The response therefore also changes in the locked condition. The resonant
response of a system therefore depends upon the amount of damping in the system (which is
determined by the relative duration of slip and stick in the system, i.e., the relative magnitude of
excitation and friction forces) and the natural frequency of the system (which alters between the
individual values and the locked condition value, depending upon the slip or stick condition).
2.3 BLADING MATERIALS Among the different materials typically used for blading are 403 stainless steel, 422 stainless
steel, A-286, and Haynes Satellites Alloy Number 31 and titanium alloy. The403 stainless steel
is
essentially the industry’s 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 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 with
stage temperatures between 900 and 1150°F (482 and 621°C). The Haynes Satellites Alloy
Number 31 is a cobalt-based super alloy and is used on jet expanders when precision cast blades
are needed. The Haynes Satellite Number 31 is used at stage temperatures between 900 and
1200°F (482 and 649°C). 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.
3. MANUFACTURING PROCESS
3.1 INTRODUCTION
Manufacturing process is that part of the production process which is directly concerned with the
change 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 or
dimensions 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 or
products with optimal process plan using proper precautions and specified safety rules to avoid
accidents. Beside above, all kinds of the future engineers must know the basic requirements of
workshop activities in term of man, machine, material, methods, money and other infrastructure
facilities needed to be positioned properly for optimal shop layouts or plant layout and other
support services effectively adjusted or located in the industry or plant within a well planned
manufacturing organization. Today’s competitive manufacturing era of high industrial
development and research, is being called the age of mechanization, automation and computer
integrated manufacturing. Due to new researches in the manufacturing field, the advancement
has come to this extent that every different aspect of this technology has become a full-fledged
fundamental and advanced study in itself. This has led to introduction of optimized design and
manufacturing of new products. New developments in manufacturing areas are deciding to
transfer more skill to the machines for considerably reduction of manual labor.
3.2 CLASSIFICATION OF MANUFACTURING PROCESSES
For producing of products materials are needed. It is therefore important to know the
characteristics of the available engineering materials. Raw materials used manufacturing of
products, tools, machines and equipments in factories or industries are for providing commercial
castings, called ingots. Such ingots are then processed in rolling mills to obtain market form of
material supply in form of bloom, billets, slabs and rods. These forms of material supply are
further subjected to various manufacturing processes for getting usable metal products of
different shapes and sizes in various manufacturing shops. All these processes used in
manufacturing concern for changing the ingots into usable products may be classified into six
major groups as
Primary shaping processes
Secondary machining processes
Metal forming processes
Joining processes
Surface finishing processes and
Processes effecting change in properties
3.2.1 PRIMARY SHAPING PROCESSES
Primary shaping processes are manufacturing of a product from an amorphous material. Some
processes produces finish products or articles into its usual form whereas others do not, and
require further working to finish component to the desired shape and size. The parts produced
through these processes may or may not require to undergo further operations. Some of the
important primary shaping processes are:
Casting
Powder metallurgy
Plastic technology
Gas cutting
Bending and
Forging
3.2.2 SECONDARY OR MACHINING PROCESSES As large number of components require further processing after the primary processes. These
components are subjected to one or more number of machining operations in machine shops, to
obtain the desired shape and dimensional accuracy on flat and cylindrical jobs. Thus, the jobs
undergoing these operations are the roughly finished products received through primary shaping
processes. The process of removing the undesired or unwanted material from the work-piece or
job or component to produce a required shape using a cutting tool is known as machining. This
can be done by a manual process or by using a machine called machine tool (traditional
machines namely lathe, milling machine, drilling, shaper, planner, slotter).
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 very
high degree of surface finish. The secondary processes require the use of one or more machine
tools, various single or multi-point cutting tools (cutters), jobholding devices, marking and
measuring instruments, testing devices and gauges etc. forgetting desired dimensional control
and required degree of surface finish on the work-pieces. The example of parts produced by
machining processes includes hand tools machine tools instruments, automobile parts, nuts, bolts
and gears etc. Lot of material is wasted as scrap in the secondary or machining process. Some of
the common secondary or machining processes are:
Turning
Threading
Knurling
Milling
Drilling
Boring
Planning
Shaping
Slotting
Sawing
Broaching
Hobbing
Grinding
Gear Cutting
Thread cutting and
Unconventional machining processes namely machining with Numerical control (NC)
machines tools or Computer Numerical Control (CNC) machine tool using ECM,
LBM, AJM, USM setups.
4. BLOCK 3 LAY-OUT Table 5: Lay-out of Block 3
5. CLASSIFICATION OF BLOCK 3
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. Asia’s largest vertical
boring machine is installed here and CNC horizontal boring milling machines from Skoda of
Czechoslovakia.
2. Assembly Section (of hydro turbines)
In this section assembly of hydro turbines are done. Blades of turbine are1st assemble on
the rotor & after it this 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 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 .In
a large tunnel, Vacuum of 2 torr is created with the help of pumps & after that rotor is placed on
pedestal and rotted with speed of 2500-4500 rpm. After it in a computer control room the axis of
rotation of rotor is seen with help of computer & then balance the rotor by inserting the small
balancing weight in the grooves cut on rotor.
Fig 4: Over speed & Vacuum Balancing Tunnel
For balancing and over speed testing of rotors up to 320 tons in weight, 1800 mm in length and
6900 mm diameter under vacuum conditions of 1 Torr.
BAY –2 IS DIVIDED IN TO 2 PARTS:
1. HMS
In 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, center
lathes, planer, Kopp milling machine.
2. Assembly Section
In this section assembly of steam turbines up to 1000 MWIs assembled. 1st moving blades are
inserted in the grooves cut on circumferences of rotor, then rotor is balanced in balancing tunnel
in bay-1.After is done in which guide blades are assembled inside the internal casing & then
rotor is fitted inside this casing. After it this internal casing with rotor is inserted into the
external.
BAY 3 IS DIVIDED INTO 3 PARTS:
1. Bearing Section
In this section Journal bearings are manufactured which are used in turbines 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.
3. Governing Section
In this section governors are manufactured. These governors are used in turbines for
controlling the speed of rotor within the certain limits. 1st all components of governor are made
by different operations then these all parts are treated in heat treatment shop for providing the
hardness. Then these all components are assembled into casing. There are more than 1000
components of Governor.
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 Copying machine, Grinding machine, Rhomboid
milling machine, Duplex milling machine, T- root machine center, Horizontal tooling center,
Vertical & horizontal boring machine etc.
Fig 5. Steam Turbine Casing & Rotors in Assembly Area
2. Turning Section
Same as the turning section in Bay-3, there are several small Machine like lathes
machines, milling, boring, grinding machines etc.
Fig 6. CNC Rotor Turning Lathe
3. Heat Treatment Shop
In this shop there are several tests performed for checking the Hardness of different
components. Tests performed are Sereliting, Nitriding, DP Test.
5. BLADE SHOP
Blade shop is an important shop of Block 3. Blades of all the stages of turbine are made in this
shop only. They have a variety of centre lathe and CNC machines to perform the complete
operation of blades. The designs of the blades are sent to the shop and the Respective job is
distributed to the operators. Operators perform their job in a fixed interval of time.
5.1 TYPES OF BLADES
Basically 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, BDS (for HP TURBINE) & F shaped blades. The most modern blades are F & Z shaped
blades. Cylindrical Profile
TX Blade
HP/IP Intermediate stages
& LP Initial
3 Dimesional
3DS Blade
HP/IP Initial Stages
Twisted Profile
F Blade
HP/IP Rear Stages
Fig. 7 Types Of Blades
5.2 OPERATIONS PERFORMED ON BLADES Some of the important operations performed on blade manufacturing are:-
Milling
Blank Cutting
Grinding of both the surfaces
Cutting
Root milling
5.3 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
Fig 8. Schmetic Diagram of a CNC Machine
5.4 NEW BLADE SHOP A new blade shop is being in operation, mostly 500mw turbine blades are manufactured in this
shop. This is a highly hi tech shop where complete manufacturing of blades is done using single
advanced CNC machines. Complete blades are finished using modernized CNC machines. Some
of the machines are:-
Pama CNC ram boring machine.
Wotum horizontal machine with 6 axis CNC control.
CNC shaping machine.
Fig 9. CNC Shaping Machine
6. CONCLUSION Gone through 1 month training under the guidance of capable engineers and workers of
BHEL Haridwar in Block-3 “TURBINE MANUFACTURING” headed by Senior Engineer of
department Mr. 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.
