VOCATIONAL TRAINING AT
Bharat Heavy
Electricals Limited
RANIPUR, HARDWAR 249403
INDIA
PROJECT
REPORT ON
TURBINE MANUFACTURING
SECTION
UNDER THE ABLE GUIDENCE OF
MR. ALOK
SHUKLA (D.G.M)
SUBMITTED BY:-
RUPAM SINGH ROLL NO. 2309628
MECH.
ENGG
AMBALA COLLEGE OF ENGG. &
APPLIED RESEARCH
MITHAPUR,AMBALA -133101
Contents
1. Prologue – A. BHEL – An Overview
B. HEEP – An Overview
2. Study on Turbines & Auxiliary Block
3. Study on Material Specification
4. Broad
Specification of Major Machines Tools & Machines
(CNC & Non CNC)
5. Other Areas
A. bhel – an overview
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 since 1971-72.
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 centre, over 150 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. BHEL has already attained
ISO 9000 certification for quality management, and ISO 14001 certification for
environment management.
POWER GENERATION
Power generation sector
comprises thermal, gas, hydro and nuclear power plant business as of
31.03.2001, BHEL supplied sets account for nearly 64737 MW or 65% of the total
installed capacity of 99,146 MW in the country, as against nil till 1969-70.
BHEL has proven turnkey
capabilities for executing power projects from concept to commissioning, it
possesses the technology and capability to produce thermal sets with super
critical parameters up to 1000 MW unit rating and gas turbine generator sets of
up to 240 MW unit rating. Co-generation and combined-cycle plants have been
introduced to achieve higher plant efficiencies. to make efficient use of the
high-ash-content coal available in India, BHEL supplies circulating
fluidized bed combustion boilers to both thermal and combined cycle power
plants.
The company manufactures 235 MW nuclear
turbine generator sets and has commenced production of 500 MW nuclear turbine
generator sets.
Custom made hydro sets of Francis, Pelton
and Kapian types for different head discharge combination are also engineering
and manufactured by BHEL.
In all, orders for more than 700 utility
sets of thermal, hydro, gas and nuclear have been placed on the Company as on
date. The power plant equipment manufactured by BHEL is based on contemporary
technology comparable to the best in the world and is also internationally
competitive.
The Company has proven expertise in Plant
Performance Improvement through renovation modernisation and uprating of a
variety of power plant equipment besides specialised know how of residual life
assessment, health diagnostics and life extension of plants.
POWER TRANSMISSION & DISTRIBUTION (T
& D)
BHEL offer wide ranging products and
systems for T & D applications. Products manufactured include power
transformers, instrument transformers, dry type transformers, series – and
stunt reactor, capacitor tanks, vacuum – and SF circuit breakers gas insulated
switch gears and insulators.
A strong engineering base enables the
Company to undertake turnkey delivery of electric substances up to 400 kV level
series compensation systems (for increasing power transfer capacity of
transmission lines and improving system stability and voltage regulation),
shunt compensation systems (for power factor and voltage improvement) and HVDC
systems (for economic transfer of bulk power). BHEL has indigenously developed
the state-of-the-art controlled shunt reactor (for reactive power management on
long transmission lines). Presently a 400 kV Facts (Flexible AC Transmission
System) project under execution.
INDUSTRIES
BHEL
is a major contributor of equipment and systems to industries. Cement,
sugar, fertilizer, refineries, petrochemcials, paper, oil and gas,
metallurgical and other process industries lines and improving system stability
and voltage regulation, shunt compensation systems (for power factor and
voltage improvement) and HVDC systems (for economic transfer of bulk power)
BHEL has indigenously developed the state-of-the-art controlled shunt reactor
(for reactive power management on long transmission lines). Presently a 400 kV
FACTS (Felxible AC Transmission System) projects is under execution.
Industries
BHEL is a major contributor of equipment
and systems to industries, cement, sugar, fertilizer, refinances,
petrochemicals, paper, oil and gas, metallurgical and other process industries.
The range of system & equipment supplied includes: captive power plants,
co-generation plants DG power plants, industrial steam turbines, industrial
boilers and auxiliaries. Wate heat recovery boilers, gas turbines, heat
exchangers and pressure vessels, centrifugal compressors, electrical machines,
pumps, valves, seamless steel tubes, electrostatic precipitators, fabric
filters, reactors, fluidized bed combustion boilers, chemical recovery boilers
and process controls.
The Company is a major producer of
large-size thruster devices. It also supplies digital distributed control
systems for process industries, and control & instrumentation systems for
power plant and industrial applications. BHEL is the only company in India with the
capability to make simulators for power plants, defense and other applications.
The Company has commenced manufacture of
large desalination plants to help augment the supply of drinking water to people.
Transportation
BHEL is involved in the development design,
engineering, marketing, production, installation, maintenance and after-sales
service of Rolling Stock and traction propulsion systems. In the area of
rolling stock, BHEL manufactures electric locomotives up to 5000 HP,
diesel-electric locomotives from 350 HP to 3100 HP, both for mainline and
shunting duly applications. BHEL is also producing rolling stock for special
applications viz., overhead equipment cars, Special well wagons, Rail-cum-road
vehicle etc., Besides traction propulsion systems for in-house use, BHEL
manufactures traction propulsion systems for other rolling stock producers of
electric locomotives, diesel-electric locomotives, electrical multiple units
and metro cars. The electric and diesel traction equipment on India Railways
are largely powered by electrical propulsion systems produced by BHEL. The
company also undertakes retooling and overhauling of rolling stock in the area
of urban transportation systems. BHEL is geared up to turnkey execution of
electric trolley bus systems, light rail systems etc. BHEL is also diversifying
in the area of port handing equipment and pipelines transportation system.
Telecommunication
BHEL also caters to Telecommunication
sector by way of small, medium and large switching systems.
Renewable Energy
Technologies that can be offered by BHEL for
exploiting non-conventional and renewable sources of energy include: wind
electric generators, solar photovoltaic systems, solar lanterns and battery-powered
road vehicles. The Company has taken up R&D efforts for development of
multi-junction amorphous silicon solar cells and fuel based systems.
International Operations
BHEL has, over the years, established its
references in around 60 countries of the world, ranging for the United States in the West to New Zealand in
the Far East. These references encompass
almost the entire product range of BHEL, covering turnkey power projects of
thermal, hydro and gas-based types,
substation projects, rehabilitation projects, besides a wide variety of
products, like transformers, insulators, switchgears, heat exchangers, castings
and forgings, valves, well-head equipment, centrifugal compressors,
photo-voltaic equipment etc. Apart from over 1110MW of boiler capacity contributed in Malaysia, and
execution of four prestigious power projects in Oman, Some of the other major
successes achieved by the Company have been in Australia, Saudi Arabia, Libya,
Greece, Cyprus, Malta, Egypt, Bangladesh, Azerbaijan, Sri Lanka, Iraq etc.
The Company has been successful in meeting
demanding customer's requirements in terms of complexity of the works as well
as technological, quality and other requirements viz extended warrantees,
associated O&M, financing packages etc. BHEL has proved its capability to
undertake projects on fast-track basis. The company has been successful in
meeting varying needs of the industry, be it captive power plants, utility
power generation or for the oil sector requirements. Executing of Overseas
projects has also provided BHEL the experience of working with world renowned
Consulting Organisations and inspection Agencies.
In addition to demonstrated capability to
undertake turnkey projects on its own, BHEL possesses the requisite flexibility
to interface and complement with International companies for large projects by
supplying complementary equipment and meeting their production needs for
intermediate as well as finished products.
The success in the area of rehabilitation
and life extension of power projects has established BHEL as a comparable
alternative to the original equipment manufactures (OEMs) for such plants.
Technology Upgradation and Research & Development
To remain competitive and meet customers'
expectations, BHEL lays great emphasis on the continuous upgradation of
products and related technologies, and development of new products. The Company
has upgraded its products to contemporary levels through continuous in house
efforts as well as through acquisition of new technologies from leading engineering
organizations of the world.
The Corporate R&D Division at Hyderabad, spread over a
140 acre complex, leads BHEL's research
efforts in a number of areas of importance to BHEL's product range.
Research and product development centers at each of the manufacturing divisions
play a complementary role.
BHEL's Investment in R&D is amongst
the largest in the corporate sector in India. Products developed in-house
during the last five years contributed about 8.6% to the revenues in 2000-2001.
BHEL has introduced, in the recent past,
several state-of-the-art products developed in-house: low-NQx oil / gas
burners, circulating fluidized bed combustion boilers, high-efficiency Pelton
hydro turbines, petroleum depot automation systems, 36 kV gas-insulated sub-stations,
etc. The Company has also transferred a few technologies developed in-house to
other Indian companies for commercialisation.
Some of the on-going development &
demonstration projects include: Smant wall blowing system for cleaning boiler
soot deposits, and micro-controller based governor for diesel-electric
locomotives. The company is also engaged in research in futuristic areas, such
as application of super conducting materials in power generations and industry,
and fuel cells for distributed, environment-friendly power generation.
Human Resource Development Institute
The most prized asset of BHEL is its
employees. The Human Resource Development Institute and other HRD centers of
the Company help in not only keeping their skills updated and finely honed but
also in adding new skills, whenever required. Continuous training and
retraining, positive, a positive work culture and participative style of
management, have engendered development of a committed and motivated work force
leading to enhanced productivity and higher levels of quality.
Health, Safety and Environment Management
BHEL, as an integral part of business
performance and in its endeavour of becoming a world-class organization and
sharing the growing global concern on issues related to Environment.
Occupational Health and Safety, is committed to protecting Environment in and
around its own establishment, and to providing safe and healthy working
environment to all its employees.
summary of BHEL's contribution
to various core sectors
Power Generation
THERMAL |
RATING (MW)
|
NO. OF SETS |
TOTAL CAPACITY
(MW)
|
|
|
500
|
30
|
15000
|
|
|
250
|
9
|
2250
|
|
|
210/200
|
138
|
28570
|
|
|
120/125/130
|
20
|
2420
|
|
|
195
|
1
|
195
|
|
|
110
|
38
|
4180
|
|
|
100
|
6
|
600
|
|
|
70/67.5
|
6
|
410
|
|
|
60
|
14
|
840
|
|
|
30
|
5
|
150
|
|
|
TOTAL (THERMAL)
|
267
|
54615
|
|
|
|
|
|
|
|
|
|
|
GAS |
FRAME SIZE/
SCOPE
|
NO. OF SETS |
TOTAL CAPACITY
(MW)
|
|
|
9
|
5
|
730
|
|
|
6
|
17
|
580
|
|
|
5
|
13
|
309
|
|
|
3
|
6
|
48
|
|
|
V 94.2
|
2
|
286
|
|
|
6FA
|
3
|
207
|
|
|
STG
|
24
|
1190
|
|
|
GEN
|
4
|
87
|
|
|
TOTAL (GAS)
|
74
|
3437
|
|
|
|
|
|
|
|
|
|
|
NUCLEAR |
RATING (MW)
|
NO. OF SETS |
TOTAL CAPACITY
(MW)
|
|
|
500
|
2
|
1000
|
|
|
220
|
10
|
2200
|
|
|
TOTAL (NUCLEAR)
|
12
|
3200
|
|
|
|
|
|
|
|
|
|
|
|
TOTAL (THERMAL+GAS+NUCLEAR)
|
353
|
61252
|
|
|
|
|
|
|
HYDRO |
|
402
|
18735
|
|
|
GRAND TOTAL
|
755
|
79987
|
Summary of BHEL's contribution to various core sectors
B. HEEP: AN OVER VIEW
Over the years, Bharat Heavy Electricals
Limited has emerged as world class Engineering and Industrial giant, the best
of its kind in entire South East Asia. Its
business profile cuts across various sectors of Engineering/Power utilities and
Industry. The Company today enjoys national and international presence
featuring in the "Fortune International-500" and is ranked among the
top 12 companies in the world, manufacturing power generation equipment. BHEL
has now 14 Manufacturing Divisions, 8 Service Centres and 4 Power Sectors
Regional Centres besides a large number of project sites spread over India and
abroad.
The Company is embarking upon an ambitions
growth path through clear vision, mission and committed values to sustain and
augment its image as a world class enterprise.
VISION
World-class, innovative, competitive and
profitable engineering enterprise providing total business solutions.
MISSION
The leading Indian engineering enterprise
providing quality products systems and services in the fields of energy,
transportation, infrastructure and other potential areas.
·
.
HEAVY ELECTRICAL EQUIPMENT PLANT (HEEP)
At Hardwar,
against the picturesque background of Shivalik Hills, 2 important manufacturing
units of BHEL are located viz. Heavy Electrical Equipment Plant (HEEP) &
Central Foundry Forge Plant (CFFP). The hum of the construction machinery woke
up Shivalik Hills during early 60s and sowed the seeds of one of the greatest
symbol of Indo Soviet Collaboration – Heavy Electrical Equipment Plant of BHEL.
Following is the brief profile of Heavy Electrical Equipment Plant:-
1. ESTABLISHMENT
AND DEVELOPMENT STAGES:
* Established in 1960s under the
Indo-Soviet Agreements of 1959 and 1960 in the area of Scientific, Technical
and Industrial Cooperation.
* DPR – prepared in 1963-64, construction
started from October '63.
* Initial production of Electric started
from January, 1967.
* Major construction / erection /
commissioning completed by 1971-72 as per original DPR scope.
* Stamping Unit added later during 1968 to
1972.
* Annual Manufacturing capacity for
Thermal sets was expanded from 1500 MW to 3500 MW under LSTG. Project during
1979-85 (Sets upto 500 MW, extensible to 1000/1300 MW unit sizes with marginal
addition in facilities with the collaboration of M/s KWU-Siemens, Germany.
* Motor manufacturing technology updated
with Siemens collaboration during 1984-87.
* Facilities being modernized continually
through Replacements / Reconditioning-Retrofitting, Technological / operational
balancing.
2. INVESTMENTS:
* Gross Block as on 31.3.95 is Rs. 355.63
Crores (Plant and Machinery – Rs. 285.32 Crores).
* Net Block as on 31.3.95 is Rs. 113.81
Crores (Plant & Machinery – Rs. 76.21 Crores).
3. CLIMATIC AND GEOGRAPHICAL:
* Hardwar is in extreme weather zone of
the Western Uttar Pradesh of India and temperature varies from 2oC
in Winter (December to January) to 45oC in Summer (April-June);
Relative humidity 20% during dry season to 95-96% during rainy season.
* Longitude 78o3' East,
Latitude 29 o55'5" North.
* Height above Mean Sea Level = 275
metres.
* Situated within 60 to 100 KMs of
Foot-hills of the Central
Himalayan Ranges;
Ganges flows down within 7 KMs from the
Factory area.
* HEEP is located around 7 KMs on the
Western side of Hardwar
city.
* Telegraphic
4. HEEP
PRODUCT PROFILE:
* THERMAL
AND NUCLEAR SETS
(Turbines,
Generators, Condensers and Auxiliaries of unit capacity upto 1000 MW)
* HYDRO
SETS INCLUDING SPHERICAL AND DISC VALVES
(Kaplan, Francis, Pelton and reversible
Turbines of all sizes and matching generators and auxiliaries maximum runner
dia – 6600 mm)
* ELECTRICAL
MACHINES:
(For various industrial applications, pump
drives & power station auxiliaries, Unit capacity upto 20000 KW AC / DC)
* CONTROL
PANELS
(For
Thermal / Hydro sets and Industrial Drives)
* LARGE
SIZE GAS TURBINES
(Unit
Rating : 60-200 MW)
* LIGHT
AIRCRAFT
* DEFENSE
PRODUCTS
TURBINE
BLOCK
Steam
turbine
Power
plant market requirements have changed in recent
years. The tendency for highly flexible
and
efficient power plants with long revision intervals, life times ≥200 000h as
well as low
investment
costs have resulted in an increased effort in the improvement of design and
materials.
One
possible way to meet high efficiency requirements is to install sub-critical
steam power
plants
with live steam temperatures of T ≥565°C and an optimized steam cycle path. As
a result,
new
challenges have arisen for the design of a two cylinder steam turbine line for
a capacity up to
700
MW. In addition, the realization of critical turbine components need improved
design and
materials,
which offer all possibilities for a cost effective and flexible service. At the
same time,
the
combined cycle power plant market demands constantly high performance,
reliability and
operating
flexibility at moderate prices for competitive life cycle costs. For this power
range, two
cylinder
designs are also typically applied for the steam turbine.
This
paper outlines the different aspects of a modular design concept. The author’s
company has
been
following this concept in recent years with an aim to accurately fulfilling
market
requirements.
It has already been applied to various aspects of the two double-casing
configurations
for both single and double-flow low pressure turbines. This paper provides
examples
on how the concept has been realized within various design aspects and
features, all
with
an underlying target to produce steam turbines that meet all named market
requirements at
competitive
prices.
INTRODUCTION
The world’s
power generation markets have been deregulated to a large extent over the past
few years, and this process is still ongoing. In order to remain competitive,
power plants need to have Features that match with the requirements of the
changing market. With the focus on cost efficient production of electricity,
the most important requirements of today are low overall lifecycle costs, high
reliability, availability and operating flexibility. Additionally, specific
customer And local site requirements need to be met by the suppliers of power
plants and components.
At the same
time, the market demands continuously decreasing turbine delivery times and
prices. Thus, one of the primary requirements of all steam turbine
manufacturers is to standardize their products in order to meet the cost and
delivery time targets while – at the same time – providing a high level of
flexibility to their customers. This also helps to obtain optimum performance levels
and product quality.
For steam
turbines, the main design parameters are the power
output, the steam conditions, the ambient temperature and the power plant
configuration. In combined cycle power plants (CCPP) these are strongly related
to the number and type of the installed gas turbines. In single-shaft units a
gas turbine and a steam turbine commonly drive a single generator. For start-up
and shutdown operations, this configuration requires a switch gear to separate
the steam turbine from the shaft train. Multi-shaft configurations use independent
gas turbine-generator and steam turbinegenerator sets. Commonly, one or two gas
turbines power a heat recovery steam generator (HRSG), which drives the steam
turbine-generator set.
Within a
given CCPP configuration, the steam conditions depend on the power output and
temperature
level of the applied gas turbine. Hence, as a result of the ongoing gas turbine
development,
steam temperatures and mass flows are increasing continuously. Typically, the current
generation of CCPPs (e.g. [8]) are designed for main steam conditions of 157
bar and
565°C, and
reheat temperatures of 565°C. However, due to the numerous gas turbines in the
market, steam
turbines need to be able to cover a wide power range for CCPP. This range may also
be considerably increased if duct-firing is applied.
For
sub-critical steam power plants (SPP) the market requires main steam
temperatures up to
600°C at main
steam pressures of 177 bar. Additionally, steam turbines for SPP need to
feature steam extractions as well as an overload injection to support an
optimum steam cycle design. In recent years the steam turbine division of the
Siemens Power Generation Group has focused on the development of two-cylinder
designs to cover the complete range of applications in CCPP and SPP up to a
steam turbine power output of 700MW. The HE series, with a single flow LP, is applied
for lower power range and high back pressures, whereas the KN series covers the
upper power range and applications with large LP flows. For both product lines,
particular effort has been made to fulfill the market requirements with respect
to performance, availability, start-up
times and
delivery times. Due to challenging price levels in the market, this could only
be
achieved with
a modular design concept. The concept allows for high flexibility in the design
phase, in
order to deliver customer specific designs using standardized modules as a
basis.
This paper
will provide an overview of the two product lines, and give details on the
application
of the
modular concept within different aspects of steam turbine design.
TWO CYLINDER DESIGNS UP TO 700MW
For the power range from 100MW to 700 MW, Siemens provides two optimized
two-cylinder steam turbine designs with single and double flow low pressure
sections. For
applications with lower power output or high back pressures, the HE
product line with single
flow LP is used. The flat floor mounted HE steam turbine set consists of
a high pressure turbine module (H) and a single flow combined intermediate/low
pressure module (E) with axial exhaust.
The H-turbine is a single-flow, full-arc admission machine. The steam
enters through one
combined control and stop valve. The H-turbine casing uses the proven
barrel-type design, which does not have horizontal flanges at the outer casing
to ensure a homogenous distribution of the forces regarding main steam pressure
and thermal load. Additionally, the design improves the
TWO CYLINDER DESIGNS UP TO 700MW
For the power range from
100MW to 700 MW, Siemens provides two optimized two-cylinder steam turbine
designs with single and double flow low pressure sections. (Fig. 1). For applications
with lower power output or high back pressures, the HE product line with single
flow LP is used. The flat floor mounted HE steam turbine set consists of a high
pressure turbinemodule (H) and a single flow combined intermediate/low pressure
module (E) with axial exhaust. The H-turbine is a single-flow, full-arc
admission machine. The steam enters through one combined control and stop
valve. The H-turbine casing uses the proven barrel-type design, which does not
have horizontal flanges at the outer casing to ensure a homogenous distribution
of the forces regarding main steam pressure and thermal load. Additionally, the
design improves the
TWO CYLINDER DESIGNS UP TO 700MW
For the power range from
100MW to 700 MW, Siemens provides two optimized two-cylinder
steam turbine designs
with single and double flow low pressure sections. (Fig. 1). For
applications with lower
power output or high back pressures, the HE product line with single
flow LP is used. The flat
floor mounted HE steam turbine set consists of a high pressure turbine
module (H) and a single
flow combined intermediate/low pressure module (E) with axial
exhaust.
The H-turbine is a
single-flow, full-arc admission machine. The steam enters through one
combined control and stop
valve. The H-turbine casing uses the proven barrel-type design, which
does not have horizontal
flanges at the outer casing to ensure a homogenous distribution of the
forces regarding main
steam pressure and thermal load. Additionally, the design improves the
Turbine Modules
For the
K-Turbine, the full
application
range from 100-700 MW
(for 60Hz) is
covered with four
module sizes
(Fig. 2). All modules
are based on
the same design
philosophy in
order to apply similar
proven design
features to all turbines.
The latest
design incorporates the K turbine
experience of
the past 30
years from
both Siemens and
Westinghouse.
The scaling
factor between the different turbine modules have beenregard to turbine
efficiency. As a result, the K-turbine family covers the complete application
range with a constantly
high performance.
Additionally, the modular
design yields further cost and delivery-time benefits to the customer.
Firstly, developmental
efforts for new K-turbine types is considerably reduced and contract
specific design work is
minimized, while at the same time the high level of reliability is
maintained. Secondly, the
long lead time items are standardized for 50Hz and 60 Hz applications
in order to reduce the
delivery times. As an example, identical casing patterns can be used for
50Hz and 60Hz as well as
for CCPP and SPP applications. Due to the design of the patterns,
required extractions and
overload admission can be added by means of separate parts.
Sub-Modules
The turbine modules are
furthermore divided into sub-modules of different sizes, which may be
combined as required.
This approach has been especially favorable for the E-turbine, since size
of the IP part is mainly
linked to the main steam flow, whereas the size of the LP part also
strongly depends on the
ambient temperature. Therefore the modular concept consists of a
standardized axial
separation plane between the IP and LP casings and of a welded rotor module.
The modular concept
yields an optimum number of
required components to
cover a wide range of
applications for both
CCPP and SPP. For the latter, an
additional set of casing
components is available with
steam extractions. Again,
the main benefits from the
modular concept are
reduced prices and delivery times
due to the standardized
long lead time items – while at
the same time a very high
performance level is
maintained.
Valves
The HP, IP and LP
admission valves comprise stop and
control valves arranged
at right angles to each other and
combined in a single
casing (Fig. 4). For both the E and
the K turbines, the valve
assembly is provided with a flange connection at the bottom of the outer
casing of the turbine.
The modular valve concept
consists of a standardized connection to the turbine casings for
different sizes. Thus
different valve sizes can be assembled to a single turbine size, and a single
valve fits to different
turbine types. Hence an optimum valve arrangement with respect to flow
velocities can always be
applied to achieve maximum element efficiency.
Bearings
The HE and the KN steam
turbine arrangements both consist of three bearings. All three bearing
pedestals are separated
from the turbine casings and are supported directly on the foundation.
Only one bearing is
located between the turbine sections to
minimize the effect of
foundation
deformation on loads to
bearings
and shaft journals. Axial
thermal
expansion of the entire
rotor train
starts at the combined
journal and
thrust bearing as the
fixed point. If
required, the bearing
pedestal can Only one bearing is located
between the turbine
sections to
minimize the effect of
foundation
deformation on loads to
bearings
and shaft journals. Axial
thermal
expansion of the entire
rotor train
starts at the combined
journal and
thrust bearing as the
fixed point. If
required, the bearing
pedestal can design with optimum
efficiencies is delivered
to the
customer.
Different to the other
elements
of the steam turbine, the
primary goal of
standardization
with regard to HP/IP
blading
has been to standardize
the
“way to the product”
instead of
the product itself. The
basis is
a strictly modular
concept of
bladepath construction
from standard and proven elements (e.g. airfoils, roots, grooves, shrouds,
extractions, locking
devices). As an example (Fig. 7), the composition of a single blade from
root, shroud and airfoil
is demonstrated. For each element, different types exist for the various
applications, each type
having its own advantages and disadvantages with respect to
performance, mechanics
and costs. Within the modular concept all these different types may be
combined freely to give
an optimum blade for the specific design boundary conditions such as
aerodynamics, forces,
materials and temperatures. Hence, cylindrical, twisted or bowed airfoils
can be assembled with any
of the roots or shrouds. Details on the concept applied for HP/IP
blading are given in
MODULAR CONCEPT TO FULFILL TEMPERATURE
AND PRESSURE REQUIREMENTS
Besides the main steam
flow, the second major design parameters are the main steam conditions.
Main steam temperatures
are continuously increasing to optimize the overall performance of
SPPs, and as in gas
turbine development, also for CCPPs. At the same time high temperatures
require expensive
material to withstand the associated optimum pressure levels. In order to keep
price increase moderate
for such advanced steam cycles, one focus of the modular concept is to
reduce the amount of
required high-temperature material to a minimum. The basic design
elements of the concept
are:
• to apply identical designs for the main components at different temperature
levels (e.g. 565°C
and 600°C) and thereby
only to change material.
• to weld main components in order to minimize the amount of
high-temperature material.
• to shield components against the hot steam. • to cool affected areas.
The application of the
concept to HE
and KN product lines will
be outlined
below.
K-Turbine Material
Concept for
Temperatures up to 600°C
The combined HP/IP
turbine (KTurbine,
Fig. 8) consists of a top
and a
bottom half of inner and
outer casings
with horizontal flanges.
The thermal
load due to the high main
steam and
reheat steam temperatures
and
pressures is completely
carried by the inner casing. For this reason, the material of the inner
casing is selected
according to the specific application temperatures. Similarly, the rotor
material
is chosen depending on
the size of the K-turbine, the application temperature and the rotational
speed (50 or 60 Hz).
Steam Temperature
Main / Reheat Steam
Variant 1
540°C / 540°C
Variant 2
566°C / 566°C
Variant 3
600°C / 600°C
Future
600°C / 620°C
Rotor
(50Hz or 60Hz) low
alloyed
low alloyed
or
high alloyed
high alloyed high alloyed
Inner Casing low alloyed
low alloyed high alloyed high alloyed
Outer Casing globular
cast
iron
globular cast
iron
globular cast
iron
globular cast
iron
Valve Casings
low alloyed
or
high alloyed
low alloyed
or
high alloyed
high alloyed high alloyed
Table 2: K-Turbine and Valve Materials
The design consists of
special features which shield the outer casing from the hot main steam and
reheat steam
temperatures. The valve is connected to the inner casing via a flexible L-ring
and a
thermo sleeve that guides
the hot steam directly into the inner casing and the HP or IP blading
respectively. As a
result, the outer casing only needs to withstand the IP-exhaust pressure andtemperature.
Therefore the outer casing material for all applications is globular cast iron,
which
yields considerable cost
reductions.
Similarly, the valve
casing materials are cost optimized for different design pressure and
temperature regimes.
As an example of the
modular material concept, an overview of the K-turbine material
combinations applied for
different main steam and reheat steam temperatures.
Welded Rotor Design
A welded design has been
applied
to the rotor of the new
E-turbine.
The 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 565°C 2%-Cr-steel is utilized
for the IP rotor block
and the inner casing. Up to 600°C, 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.
Cooling of Dummy Piston
To achieve maximum
thermodynamic efficiencies, a straight-flow design was chosen for the new
E-turbine. In contrast to
a reverse-flow concept, the chosen straight-flow design requires a large
IP piston diameter for
sufficient axial thrust compensation. Due to the mechanical impact of this
large piston diameter at
reheat temperatures, a forced rotor cooling has been developed for the IP
piston to ensure high
life cycles. Cooling steam (350°C) from the cold reheat is blown into a special
mixing space in front of the
IP piston and mixed with
hot reheat steam (between 565°C and 600°C) from the IP inlet to
achieve an optimum
temperature of 450°C. At this temperature, two advantages for both the IP
rotor and the IP piston
are combined: optimum rotor life cycles and minimum clearances at the
IP piston seal. Thereby
2%-Cr-steel can be used for the IP rotor up to temperatures of 565°. Thus,
performance and
reliability remain at a high level without increasing material costs. The
cooling
system has successfully
been tested in E-turbines with high temperature capability in the US market.
MODULAR CONCEPT FOR OPTIMUM LP ENDS FOR A WIDE RANGE OF CONDENSER PRESSURES
The third major design
parameter with respect to modularity is the volume flow through the LP
end stages, which is
directly connected to the mass flow and the condenser pressure. The
performance of the last
stages and the exhaust diffuser is strongly related to the mean axial
velocity in this area. A
number of different LP sizes are therefore required to cover the range of
condenser pressures
without compromising the performance of the LP section. In this case, the
focus of the modular
concept is to achieve an optimum balance between maximum LP
performance and moderate
costs. Therefore, the main targets where set
• to define an optimum set of LP standard stages to cover the required
range of volume flows.
• to enable cost effective connections of all required combinations of LP
and IP components
• and thereby to maintain optimum
performance.
Thereby, a large
condenser pressure range of
20 to 200mbar is being
considered.
LP Blading
Since the axial velocity
after the last blade is
primarily related to the
exit area (and not to
length of the last
blade), a homogenous
distribution of exit
areas has been chosen for
the Siemens family of LP
standard stages . For each of the given exit areas, a
Free Standing LP End Blades
In general, the last two
rows of LP moving blades are designed as free-standing blades with
curved fir-tree roots for
a homogenous stress distribution. The highly-efficient three-dimensional
airfoil design consists
of super-sonic tip section for the large end blades (Fig. 10). The inlet edge
is flame or laser
hardened, respectively, to prevent from droplet erosion.
Additional erosion
protection measures are applicable to the last stationary blades. They are
designed as hollow blades
that either consist of drainage slots (Fig. 11) to remove moisture from
the blade surface or can
be heated with steam. An advanced three-dimensional airfoil design is
applied in order to
increase stage reaction at the blade hub and hence improve performance at
low loadIn order to allow
for larger axial
movement due to thermal
expansion,
non-interlocking
labyrinth seals are
applied within the LP
section of the
turbine. The seal design
provides an
optimum sealing
efficiency within a
relatively short seal
length.
LP Exhaust Casing for Single Flow ETurbine
The modular concept of
the E-turbine
provides only three
different LP exhaust
casings to cover the
complete exit area
range specified in table
1. The six
related sets of standard
LP stages are
installed by means of
standardizedinterfaces. Also, the axial joint between the LP exhaust casing and
the IP outer casing is a standard interface that allows any combination
of sizes of the two
casings. Fig. 12 shows the LP exhaust casing module for the 12.5m2 exhaust
section.
Exhaust Geometry Optimization
Detailed computational
fluid analyses are performed in the design phase, in order to optimize the
geometry of the LP
turbine exhaust as well as the transition region to the condenser. In
conjunction with
measurements on models and on turbines in the field, effort is focused on
increasing exhaust
pressure recovery and hence improving the overall steam turbine
performance.
As an example, Fig. 13
shows the results of an exhaust analysis with flow lines for a classic
turbine deck arrangement
with the condensers mounted below the turbine. The steam flow
downstream of the last
turbine stage passing into the exhaust hood shows considerable vortices,
which were also observed
in the flow in the exhaust casing itself. As vortices cause energy loss
in the flow, guide vanes
have been installed to improve flow and thereby reduce pressure losses.
SUMMARY
For a power range from
100MW up to 700MW Siemens provides the HE and KN steam turbine
product lines for both CCPP
and SPP. Both turbo sets consist of a two casing design. The HE is
applied where a single
flow LP section is
sufficient to take the
steam flow at optimum
velocities. For large
power output and low
condenser pressures the
KN product line with a
double flow LP turbine is
applied.
Both designs are based on
a modular design
concept. Details have
been given in the paper on
how the concept is
applied to compensate for
the effects of the major
design parameters power
output, temperature and
condenser pressure.
Thereby, the main targets
are to reduce the
number of variants of
major components and to
minimize the material
cost impact of high
temperatures.
The concept has
successfully been applied within the HE and KN product lines and is seen a
fundamental basis to
fulfill the challenging requirements in today’s steam turbine market. The
reduced number of major
components ensures short delivery times and low costs. At the same
time the concept stands
for reliability due to the application of proven Siemens technology and
similar designs
through-out each set of module sizes. Special design features such as the
welded
E-turbine rotor
contribute to short start-up times and operational flexibility. All
configurations
consist of Siemens latest
LP standard stage designs. In the HP and IP sections a highperformance
fully three-dimensional
reaction blading is applied, which is designed on a contract
specific basis to provide
maximum blade path efficiency.
Hence, Siemens’ two
casing designs have been optimized to fulfill the market’s most important
requirements of low
overall life cycle costs, high reliability, availability and operating
flexibility
in order to support the
customer focus on cost efficient production of electricity.
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) 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 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.
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.
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 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.
BROAD SPECIFICATION OF
MAJOR/IMPORTANT
MACHINE TOOLS & MACHINES
CNC MACHINE TOOLS
CNC HORIZONTAL
BORERS:
1. Item
Description : CNC Horz. Borer
Model : RAPID 6C
Supplier : WOTN,
GERMANY
CNC
Control System : FANUC 12M
Spindle
Dia. : 200mm
Table : 4000 x 4000 mm
Max. Load on Table : 100 T
Travers : X=20000,
Y=5000, X=1400mm
Ram traverse : W = 1000 mm
Ram
size : 400 x 400 mm
Power
Rating : 90 KW
Weight
of the m/c : 111 T
ATC
Capacity : 60 Nos.
Plan
No. : 1-227 (Block-I)
CNC LATHES
2. Items
Description : CNC Centre Lathe
Supplier : HOESCH MFD, GERMANY
Centre
Distance : 8000 mm
Swing
Over Carriage : 1800 mm
Swing
Over Bed : 2400 mm
Spindle
Speed : 0 – 125 RPM
Power
Rating : 92 KW
Weight
of the Job : 110 TON
Weight
of the m/c : 124 TON
Plan
No. : 2-394 (Block-III)
CNC MILLING
MACHINES
3. Item
Description : CNC Horz. Milling M/c (6 Nos.)
Model : BFH-15
Supplier : BATLIBOI,
INDIA
CNC
Control System : SINUMERIK 810 M
Table : 1500 x 400 mm
Traverse : X=1170
mm
Y=420
mm
Z=420
mm
Spindle
Speed : 45 to 2000 RPM
Power
Rating : 11 KW
Max.
Load Capacity : 630 Kg
Weight
of the m/c : 4200 Kg
Plan
No. : 2-449, 2-453, 2-454, 2-459, 2-460
(Block-
III:TBM)
CNC
MACHINING CENTRES
4. Item
Description : SPL. Purpose 6 Station T-Root Machining
Centre (2nos.)
Supplier : MIH,
JAPAN
CNC
Control System : FANUC 7M
Indexing
Table : 1900 mm dia
Indexing
Position : 6 Nos.
Plan
No. : 2-356, 2-41 (Block-III: TBM)
CNC VERTICAL
BORERS
5. Item
Description : CNC Vertical Borer
Model : TMD – 40 / 50
Supplier : OSAKA
MACHINES, JAPAN
CNC
Control System : FANUC 6TB, 3TC
Table
dia : 4000 mm
Turning
dia : 5000 mm
Turning
Height : 4200 mm
Spindle
Speed : 0.23-30 RPM
No.
of Ram : 2
Power
Rating : 75 KW
Max.
Load Capacity : 70T
OTHER SPECIAL PURPOSE CNC MACHINES
6. CNC
SURFACE BROACHING M/C
Make : Marbaix
Lapointe, UK
Model : Champion 32 /10, 300
CNC System : SINUMERIC
850 M
Broaching capacity (pulling force) : 320
KN
Broaching slide stroke : 10.3 mm
Broaching slide width : 1500 mm
Max tool length (continuous /row) : 9650
mm
Broaching Speed (cutting stroke) : 1-25
M/min
Broaching Speed (return stroke) : 60
M/min
Drive power rating : 135 KW
Broaching slide movement : Electro-mechanical
Maximum noise level : < 80 Dbs
Max. dia of the disc (mountable) : 2300
mm
Max. weight of the job : 3000 Kgs
Indexing & rotating tables f : 1500
mm, 1000 mm
Indexing accuracy : +/- 3 Arc sec.
Plan No. : 2-485
7. CREEP FEED GRINDING M/C
Make : ELB CHLIFE,
GERMANY
Model : ELTAC SFR 200 CNC
CNC System : SINUMERIC
3 GG
Work-piece diameter : 200 – 2000 mm
Work height : 2400
mm
Rotary & indexing table dia. : 2050
mm
Indexing accuracy : +/- 1 ARC SEC
Max. load capacity : 20000 KG
Y-axis (grinding head movement)
Vert. Traverse : 750
mm
Z- axis (grinding head support)
Movement on cross rail)
Horizontal traverse : 2400 mm
Traverse feed rate : 02 – 1200 mm /min
Grinding head main support
Drive motor : 34
KW
Grinding wheel max. dia. : 500
mm
Max. width : 100
mm
Bore : 203.2 mm
Surface speed : 16-35
M/Sec.
Plan No. : 2-491
8. BROACH SHARPENING M/C
Make : LANDRIANI,
ITALY
CNC System : SELCA
Work-piece diameter : Upto 250 mm
Work Length : 200
mm
Plan No. : 2-487
BROAD SPECIFICATIONS OF
MAJOR / IMPORTANT MACHINE TOOLS &
MACHINES
B: NON-CNC MACHINE TOOLS
-UNIVERSAL VERTICAL TURNING & BORING MACHINE
-SPECIAL DRILLING & BORING MACHINE
-SPECIAL INTERNAL GRINDING MACHINE
-PLANER
materials specification
X20
– Cr – 13
A. 13% Cr. Stainless Steel
Bars (Hardened & Tempered)
1. General : This specification governs the quality of stainless steel bars
of grade X20 – Cr. –13
2. Application : For machining of moving and guide blades of steam Turbine.
3. Condition of Delivery : Hot
rolled / Forged & hardened and tempered. The bars shall be straight and
free from waviness.
4. Complete with standards: There is no Indian standard covering this
material.
5. DIMENSIONS & TOLERANCES
:
Dimension : Bars shall be supplied to the dimensions specified in the
purchase order unless otherwise specified in the order. The bars shall be
supplied in random length of 3 to 6 meters with a maximum of 10% shorts down to
meter.
Ø Forged
bars shall be supplied in length of 1.5 to 3 meters.
Tolerance : The tolerance on cross sectional dimensions shall be as per
table.
5.1.
Hot Rolled Bars : Tolerance on hot rolled flat bars shall be
as specified below :
|
b
|
|
s
|
|
"b"
width across flates mm
|
Allowable
deviation on "b" mm
|
"s"
thickness mm
|
Allowable
devi. on 'S' mm
|
|
Up
to 35
|
+
1.5
|
Up
to 20
|
+1
|
|
Over
35 and Upto 75
|
+
2
|
Over
– 20 and Upto – 40
|
+
2
|
|
Over
75
|
+
3
|
Over
40
|
+
3
|
Note
: Other tolerances shall be as per DIN 1017. Twisting and bending off the bars
shall not exceed 0.001X length of the bar. Bulging on the sides shall not be
more than 0.01 x b and 0.01 x s respectively.
5.2 Forged Bar : Tolerances on size for forged bars shall be +8% of the size.
6. MANUFACTURE :
6.1 The
steel shall be manufactured in basic electric furnace process and subsequently
vacuum degassed or electric slag refined (ESR). Any other process of meeting
shall be subjected to mutual agreement between supplier & BHEL.
6.2 For
manufacture of flat bars, if initial material is other than ignot (e.g.
continuous casting), supplier shall mention it in his quotation for prior
approval from BHEL.
7. HEAT
TREATMENT :
7.1 The bars shall be heat treated to get the desired
mechanical properties specified in this
specification. The hardening temperature shall be in the range of 980 – 10300C
and the tempering temperature shall not be below 6500C As per
DIN-19440.
7.2. Minimum possible residual stress shall be aimed with slow cooling and
longer duration of tempering treatment.
7.3. If
the bars require straightening after heat treatment, the bars shall be stress
relieved after straightening operation at 300C below the actual
tempering temperature.
8. FREEDOM FROM DEFECTS :
8.1 The
bar shall be free from lamination cracks, scabs, seams, shrinkage porosity,
inclusions and other harmful defects.
8.2 Decarburisation and other material defects shall not exceed the
dimensional tolerances and machining allowances.
9. FINISH :
9.1 The
bar surface be smooth, free from laps, rolled in scale etc. Dents roll marks.
Scratches are permitted provided their depth does not exceed half the tolerance
limits specified in table.
9.2 Repair of surface flaws by welding in not permitted
9.3 The
edges of bars shall be cut square by swaing or shearing.
10. CHEMICAL COMPOSITION
: The chemical composition of material
shall be as follows (table analysis in %)
|
Element
|
Min.
|
Max.
|
|
Carbon
|
0.17
|
0.22
|
|
Silicon
|
0.10
|
0.50
|
|
Manganese
|
0.30
|
0.80
|
|
Chromium
|
12.50
|
14.00
|
|
Nickel
|
0.30
|
0.80
|
|
Sulphur
|
--
|
0.020
|
|
Phosphorus
|
--
|
0.030
|
11. SELECTION
OF TEST SAMPLES :
11.1 Chemical analysis shall be reported on each heat basis..
11.2 For
Mechanical Test
11.2.1 One tensile & 3 impact test
samples shall be selected for mechanical testing per melt per heat
treatment batch basis from lot of size.
11.2.2 The uniform strength of a delivery shall be certified through
hardness test. In case of bars with sectional dimensions more than 120mm, all the
bar shall be tested for hardness. In case of bars with sectional dimension less
than or equal to 120mm hardness shall be checked on 10% of the bars or 10
numbers of bars which ever is higher.
11.2.3 The mechanical and notch impact test is to be done in longitudinal
direction on the hardest and softest bars. Test sample shall be to Km. at 1/3rd
below the surface of the bars.
12. Mechanical Properties :
12.1 The material
shall comply with the following mechanical properties at room temperature.
0.2% : 600 N/MM2 Min
Tensile strength : 800 – 950 N/mm2
% Elongation on 5.65
: 15 min.
% reduction in area : 50 min. *
Impact (mean of 3.1S0 – V sample) : 20
J min.
Hardness (HB-30) :
280
*
The smallest value shall be at least 14 J.
12.2 Tensile
test shall be carried out in accordance with IS : 1608 or equivalent
international standard.
12.3 Impact
test shall be carried out on 3 ISO-V samples in accordance with IS : 1757 or
equivalent international standard only one test value out of three, can be
below the specified value ; but in no case it should be below 2/3rd of the
minimum specified value; but in no case it should be below 2/3rd of the minimum
specified impact value.
12.4 Hardness
test (Brinell) shall be carried out according to IS : 1500 or equivalent
international standard.
13. NON DESTRUCTIVE TEST : Following NDT shall be carried out.
13.1 UT of the prematerial combined with 100% magnetic partial
testing of all bars in delivery condition.
13.2 Complete
UT of all bars in delivery condition.
13.2.1 In case of testing as per 14(a) U.T. shall be carried out as
per HW 0850 192 (SEP 1923) test class D3 and MPI of all bars except
of face areas. In case of testing as per 14(b) UT shall be carried out as per
HW 0850 192 (SEP 1923) test class D2.
13.2.2 Mix up test (verification test) of all bars.
13.2.3 Visual inspection of all bars
13.2.4 Acceptance Criteria
a) Magnetic
Particle Test : When MT is carried out
as per clause 14.1.
·
Surface defects with expected depth > 1
mm are unacceptable.
·
Indication > 5 mm are unacceptable.
Defect
indication observed during MT, can be removed by grinding (dressing up) but
with in 1mm depth.
b) Ultrasonic
Test :
Quality class 2b with following modification that individual indication
> 2mm EFB (KSR) and back wall losses > 3dB are unacceptable.
X2 – CrMoV1
21
B.
600 N/MM2 minimum 0.2% Proof stress Heat resistant steel bars
for steam turbine blades
1. General : Hot
rolled and forged bars of steel grades X22 CrMoV1 21.
|
s
|
3. Dimension & Tolerance :
|
b
|
|
"b"
width across flates mm
|
Allowable
deviation on "b" mm
|
"s"
thickness mm
|
Allowable
devi. on 'S' mm
|
|
Up
to 35 & Over 35
|
± 1.5
|
Up to 20 & Over 20
|
+1
|
|
Upto
75
|
+ 2
|
Upto – 40
|
+ 2
|
|
Over
75
|
+ 3
|
Over 40
|
+ 3
|
4. Chemical
Composition :
Element % min. %
max.
Carbon 0.18 0.24
Silicon 0.10 0.50
Manganese 0.30 0.80
Chromium 11.00 12.50
Malybeonum 0.80 1.20
Vanadium 0.25 0.35
Nickel 0.30 0.80
Sulphur -- 0.020
Phosphorous -- 0.030
5.
MECHANICAL PROPERTIES :
0.2 % proof stress : 600 N/mm2 min.
Tensile Strength : 800-950 N/MM2
%
Elongation : 14 Min.
% Reduction in area : 40% Min.
Notch Impact Value : 27 J * Min.
*
Average of 3 IS0 – V Samples.
C. 600 N/MM2 0.2% Proof Stress Forged Blades
1. General : This
specification governs the quality of guide and moving blades forged from steel
grade X 20 or 13.
2. Application : The
blades are used for steam turbines.
3. Condition of Delivery: The forged blades shall be supplied in heat
treated forged blade shall be supplied with center holes made in accordance
with respective technical requirements or ordering drawing.
4. Dimensions & Tolerance: The dimension and tolerances shall be as per
ordering drawing accompanying the order.
5. Manufacture : The
steel shall be manufactured in the blade electrical furnace and for
subsequently refined to ensure turbine blade quality. The forgings shall be
made as envelope forging or precision forging, subsequently machine / grinder
to achieve the ordering drawing dimensions and surface finish.
6. Heat Treatment
:
6.1. The forging shall be heat treated to get
desired mechanical properties.
6.2. The tempering temperature shall not be below 6500 C.
The minimum residual are to be aimed through sufficient duration of the
tempering treatment and the slow cooling rate from the tempering temperature.
6.3. The blades are to be straightened after heat treatment, each
straightening operation is to be followed by a stress relieving temperature and
in no case below 6100C followed by slow cooling.
7. Freedom from Defects
: Blades shall be free from folds due to
forging ; cracks, tearing and other material defects, elonganed non-metallic
and jusions, seams etc. any blade blade containing such defects shall be
rejected.
8. Surface finish : The
blade shall be supplied in a desoaled and deburred condition. The surface
finish shall comply with the requirements specified on the drawing. In the
surface is ground prior to blasting the the surface finish must be anouired in
compliance with the finish specified on the drawing. Grinding may be performed
to a depth not more than DH/2
and ground areas shall be blended over a length of LP/2. However DH Shall not be exceeded.
DH : Allowable profile deviation on the pressure side.
LP :
Profile length measured from
leading edge to trailing edge.
9. Chemical Composition
: The chemical analysis of the material
shall confirm to the following :
Element %
min. % max.
Carbon 0.17 0.22
Silicon 0.10 0.50
Manganese 0.30 0.80
Chromium 12.50 14.00
Nickel 0.30 0.80
Sulphur -- 0.020
Phosphorous -- 0.030
10. Selection
of Test Sample : All tests and examination shall be
performed on specimens taken in accordance with annexure 1 from at least one
blade of each drawing per melts and heat treatment batch.
11. Mechanical properties
:
11.1 The mechanical properties of the blade
material shall conform to the following :
0.2 % proof stress :
600 N/mm2
Tensile Strength : 800-950 N/MM2
%
Elongation : 15 Min.
% Reduction in area : 50 Min.
Impact Value (Average of
3, ISO – V Sample) : 20 J Min.
Brinell
hardness HB 30 : 280 Max.
11.2 Tensile Test : The tensile
test piece shall confirm to the gauge length.
11.3 Impact test shall be carried out on standard
test piece as per ISO – V notch according to IS : 1757.
11.4 Hardness Test : The brinell hardness test HB 30 shall be
carried out according to IS : 1500.
shipment.
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