This document is a seminar report submitted by Mr. Ganesh Vasant Nirgude to the University of Pune on supercritical technology in power plants. It includes a certificate from the college confirming Mr. Nirgude presented the seminar. The report contains an introduction on the basic Rankine cycle and efficiency factors. It also discusses supercritical Rankine cycles, design aspects of supercritical boilers, material selection challenges, and advances in supercritical technology for the future in India.
Thermal Power plant familarisation & its AuxillariesVaibhav Paydelwar
PPT in Relation to Power Plant familarisation, Coal to Electricity Basics,Power Plant cycles, Concepts of Supercritical Technology Boiler, Concepts Of BTG Package as well as Balance of Plant
The writeup details the Heat Balance of BHEL 210 MW Turbine Cycle. The Input and Output steam condition of Turbines, Extractions, Deaerator, LP Heaters, Condensers etc have been computed as per the specifications of the turbine manufacturer
Thermal Power plant familarisation & its AuxillariesVaibhav Paydelwar
PPT in Relation to Power Plant familarisation, Coal to Electricity Basics,Power Plant cycles, Concepts of Supercritical Technology Boiler, Concepts Of BTG Package as well as Balance of Plant
The writeup details the Heat Balance of BHEL 210 MW Turbine Cycle. The Input and Output steam condition of Turbines, Extractions, Deaerator, LP Heaters, Condensers etc have been computed as per the specifications of the turbine manufacturer
Super Critical Technology-Fundamental Concepts about Super Critical Technolog...Raghab Gorain
Nicely describe everything about super critical technology in thermal power plant.This slide is very useful for the freshers.Anybody can get the basic fundamental idea about super critical technology from this slide. In India now we have to think some new technology for power sources as sub critical power plants are less efficient and emit more pollutant to the environment and the alternative is the 'Super Critical Power Plant'.
Boiler Water Circulation Pumps
1 SCOPE
2 CHOICE OF TYPE AND NUMBER OF PUMPS
2.1 Need for Continuous Flow
2.2 Pump Reliability
3 CHOICE OF DRIVER
4 DUTY CALCULATIONS
5 CHOICE OF SEAL
5.1 Mechanical Seals
5.2 Soft-packed Glands
5.3 Construction Features
5.4 Guarding
6 CONSTRUCTION FEATURES
6.1 Vertical Glandless Wet-stator Motor Pumps
7 LAYOUT
7.1 Non-return Valves
7.2 Reducers at Pump Connections
7.3 Glandless Pumps for System Pressures
Exceeding 60 bar abs
7.4 Access round Glandless Pumps
7.5 Cooling Water Supply
8 RECOMMENDED LINE DIAGRAMS
8.1 Horizontal Pumps in Category 1
8.2 Vertical Wet-stator Motor Pumps in Category
APPENDICES
A PROPERTIES OF WATER AT THE SATURATION LINE
B ANNEX TO API 610, 6TH EDITION 1981:
VERTICAL GLANDLESS WET-STATOR MOTOR PUMPS
C ANNEX TO API 610, 6TH EDITION 1981:
HORIZONTAL BACK PULL-OUT PUMPS FOR BOILER
WATER CIRCULATION DUTY
FIGURES
3.1 NPSH CORRECTION FOR WATER
3.2 VELOCITY OF SOUND IN WATER AT 50 BAR
(NO BUBBLES)
3.3 VELOCITY OF SOUND IN WATER AT 50 BAR
(WITH 3% VAPOR CONTENT)
8.1 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - CATEGORY 1
8.2 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - SOFT PACKED GLAND INSTALLATION
8.3 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - MECHANICAL SEAL INSTALLATION
8.4 RECOMMENDED LINE DIAGRAM VERTICAL WET STATOR PUMPS - CATEGORY 2
BIBLIOGRAPHY
the presentation describes in details about the feed water and condensate heaters used in Thermal Power Stations or elsewhere. The performance parameters of the heaters are also described in details.
Boiler Efficiency Improvement through Analysis of Lossesijsrd.com
Thermal is the main source for power generation in India. The percentage of thermal power generation as compare to other sources is 65 %. The main objective of thermal power plant is to fulfill the energy demands of the market and to achieve these demands; plant requires technical availability with the parts reliability and maintenance strategy. This paper deals with the determination of current operating efficiency of Boiler and calculates major losses for Vindhyachal Super thermal power plant (India) of 210 MW units. Then identify the causes of performance degradation. Also find the major causes of heat losses by Fault Tree Analysis (FTA) and recommends its appropriate strategy to reduce major losses. The aim of performance monitoring is continuous evaluation of degradation i.e. decrease in performance of the steam boiler. These data enable additional information which is helpful in problem identification, improvement of boiler performance and making economic decisions about maintenance schedule.
210 MW Turbine Cycle Heat Rate includes all parameters of Steam and Condensate at various inlets and outlets of HP, IP and LP Turbines, Condenser and also takes into consideration the regenerative HP, IP/LP Heaters in the Turbine Cycle. Well Illustrated with all diagrams.
Design of superheater for 210 MW thermal powerplant finalKundan Chakraborty
A project based on various aspects of a basic thermal power plant.
Includes basic concepts, components of a thermal power plant and their functions. It also includes detailed data on basics of a superheater, their types, advantages and disadvantages,etc.
Super Critical Technology-Fundamental Concepts about Super Critical Technolog...Raghab Gorain
Nicely describe everything about super critical technology in thermal power plant.This slide is very useful for the freshers.Anybody can get the basic fundamental idea about super critical technology from this slide. In India now we have to think some new technology for power sources as sub critical power plants are less efficient and emit more pollutant to the environment and the alternative is the 'Super Critical Power Plant'.
Boiler Water Circulation Pumps
1 SCOPE
2 CHOICE OF TYPE AND NUMBER OF PUMPS
2.1 Need for Continuous Flow
2.2 Pump Reliability
3 CHOICE OF DRIVER
4 DUTY CALCULATIONS
5 CHOICE OF SEAL
5.1 Mechanical Seals
5.2 Soft-packed Glands
5.3 Construction Features
5.4 Guarding
6 CONSTRUCTION FEATURES
6.1 Vertical Glandless Wet-stator Motor Pumps
7 LAYOUT
7.1 Non-return Valves
7.2 Reducers at Pump Connections
7.3 Glandless Pumps for System Pressures
Exceeding 60 bar abs
7.4 Access round Glandless Pumps
7.5 Cooling Water Supply
8 RECOMMENDED LINE DIAGRAMS
8.1 Horizontal Pumps in Category 1
8.2 Vertical Wet-stator Motor Pumps in Category
APPENDICES
A PROPERTIES OF WATER AT THE SATURATION LINE
B ANNEX TO API 610, 6TH EDITION 1981:
VERTICAL GLANDLESS WET-STATOR MOTOR PUMPS
C ANNEX TO API 610, 6TH EDITION 1981:
HORIZONTAL BACK PULL-OUT PUMPS FOR BOILER
WATER CIRCULATION DUTY
FIGURES
3.1 NPSH CORRECTION FOR WATER
3.2 VELOCITY OF SOUND IN WATER AT 50 BAR
(NO BUBBLES)
3.3 VELOCITY OF SOUND IN WATER AT 50 BAR
(WITH 3% VAPOR CONTENT)
8.1 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - CATEGORY 1
8.2 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - SOFT PACKED GLAND INSTALLATION
8.3 RECOMMENDED LINE DIAGRAM HORIZONTAL PUMPS - MECHANICAL SEAL INSTALLATION
8.4 RECOMMENDED LINE DIAGRAM VERTICAL WET STATOR PUMPS - CATEGORY 2
BIBLIOGRAPHY
the presentation describes in details about the feed water and condensate heaters used in Thermal Power Stations or elsewhere. The performance parameters of the heaters are also described in details.
Boiler Efficiency Improvement through Analysis of Lossesijsrd.com
Thermal is the main source for power generation in India. The percentage of thermal power generation as compare to other sources is 65 %. The main objective of thermal power plant is to fulfill the energy demands of the market and to achieve these demands; plant requires technical availability with the parts reliability and maintenance strategy. This paper deals with the determination of current operating efficiency of Boiler and calculates major losses for Vindhyachal Super thermal power plant (India) of 210 MW units. Then identify the causes of performance degradation. Also find the major causes of heat losses by Fault Tree Analysis (FTA) and recommends its appropriate strategy to reduce major losses. The aim of performance monitoring is continuous evaluation of degradation i.e. decrease in performance of the steam boiler. These data enable additional information which is helpful in problem identification, improvement of boiler performance and making economic decisions about maintenance schedule.
210 MW Turbine Cycle Heat Rate includes all parameters of Steam and Condensate at various inlets and outlets of HP, IP and LP Turbines, Condenser and also takes into consideration the regenerative HP, IP/LP Heaters in the Turbine Cycle. Well Illustrated with all diagrams.
Design of superheater for 210 MW thermal powerplant finalKundan Chakraborty
A project based on various aspects of a basic thermal power plant.
Includes basic concepts, components of a thermal power plant and their functions. It also includes detailed data on basics of a superheater, their types, advantages and disadvantages,etc.
introduction to thermal powerplant,type of thermal powerplant,captive powerplant,rankin cycle,co-generation powerplant,subcritical powerplant,supercritical powerplant,theory of operation,working principle,parts of powerplant,boiler,turbine,etc
Thermal Analysis of Steam Turbine Power PlantsIOSR Journals
: Steam are a major energy consumer. Optimising process operating conditions can considerably
improve turbine water rate, which in turn will significantly reduce energy requirement. Various operating
parameters affect condensing and back pressure turbine steam consumption and efficiency. The industrial
sector is the largest energy consumer, accounting for about 30 % of total energy used. Fuel and energy prices
are continuously rising. With the present trend of energy prices and scarcity of hydrocarbon resources lowering
energy requirement is a top priority. Energy conservation benefits depend on the adopting minor or major
modifications and using the latest technology. Turbines are designed for a particular operating conditions like
steam inlet pressure, steam inlet temperature and turbine exhaust pressure/ exhaust vacuum, which affects the
performance of the turbines in a significant way. Variations in these parameters affects the steam consumption
in the turbines and also the turbine efficiency. The present study was done to improve the power output of the
turbine, thermal efficiency and specific steam consumption in conventional steam power plants. Three cycles i.e
regenerative cycle, superheater cycle and cogeneration cycle are considered to formulate the data and obtain a
better result in steam turbine power plants
In any thermal power generation plant, heat energy converts into mechanical work. Then it is converted to electrical energy by rotating a generator which produces electrical energy.
A detailed explanation about Rankine cycle or vapour power cycle for mechanical 2nd year students.Areas of uses of vapour power cycle or steam power cycle.
performance analysis of steam power plants using ideal reheat rankin cycleIJAEMSJORNAL
In this paper, a hypothetical examination has been done to assess the execution of the power plants that are chipping away at Reheat-Rankin cycle. The execution of cycle was dissected for various (warm, evaporator, condenser weights) values and also warm temperature qualities to demonstrate its impact on cycle warm proficiency. In this work, the heater weights qualities was accepted limited between (10to 26 MPa), the pressure proportion (warm stage weight to evaporator weight) was expected fluctuated in wide range from (0.1 to 1.0), while the condenser weight was accepted shifted between (5 to 25 kPa). And, a variety in warm temperature esteem was done between scopes of (400-600oC) at low weight turbine. The outcomes demonstrate that the warm productivity is considerably upgraded when the pressure proportion lies between (0.25-0.35) and the ideal proficiency is gotten when the pressure proportion and evaporator weight are equivalent to( 0.33 and 26MPa) separately .
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
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The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
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Seminar report on supercritical thenology
1. I
Seminar Report
On
SUPERCRITICAL TECHNOLOGY IN
POWER PLANT
Submitted to
UNIVERSITY OF PUNE
Submitted By
Mr. GANESH VASANT NIRGUDE
DEPARTMENT OF MECHANICAL ENGINEERING
ShriChhatrapatiShivaji College Of Engineering
Shrishivajinagar (Rahuri Factory),
Tal: Rahuri, Dist: Ahmednagar.
Academic Year 2012-2013
2. II
ShriChhatrapatiShivaji College Of Engineering
Shrishivajinagar (Rahuri Factory),
(Recognized by Pune University)
Department of Mechanical Engineering,
CERTIFICATE
This is to certify that the seminar report entitled
SUPERCRITICAL TECHNOLOGY IN
POWER PLANT
Is submitted as partial fulfillment of curriculum of T.E. Mechanical
Engineering. Conferred by the University of Pune.
By Mr. GANESH VASANT NIRGUDE
Prof . Shelke S.V. Prof. Pandharkar U.J
(Seminar Guide) (Seminar Co-ordinator)
Prof.Dongare A.D.
(Head of department)
3. III
University of Pune
CERTIFICATE
This is to certify that
Mr. GANESH VASANT NIRGUDE
Student of T.E. Mechanical engineering was examined in the
seminar Presentation entitled
On 23 / 10/ 2012
“SUPERCRITICAL TECHNOLOGY IN
POWER PLANT”
At
Department of Mechanical Engineering,
Shri Chhatrapati Shivaji College Of Engineering.
Prof.Shelke S.V. Prof.Pandharkar. U.J
(SeminarGuide) (Seminar Co-ordinator)
4. IV
ACKNOWLEDGEMENT
Every orientation work has imprint of many people and this work is no
different. This work gives me an opportunity to express deep gratitude for
the same.
While preparing seminar report I received endless help from number of
people. This report would be incomplete if I don’t convey my sincere
thanks to all those who were involved.
First and foremost I would like to thank my respected guide Prof. .Seminar
coordinator Prof.Pandharkar U.J. and HOD Prof.Dongare A.D.
(Department of Mechanical Engineering) for giving me an opportunity to
present this seminar and there indispensable support, priceless suggestions
and valuable time.
Finally, I wish to thanks my friends and my family for being supportive of
me, without whom this seminar would not have seen the light of day.
Every work is an outcome of full-proof planning, continuous hard work
and organized effort. This work is a combination of all the three put
together sincerely.
Mr. Nirgude Ganesh Vasant
5. V
LIST OF CONTENENT
SR
NO
TOPIC PAGE
NO
ABSTRACT
1 INTRODUCTION
1-5
1.1Basic rankine cycle
1.2Energy Analysis of the Rankine Cycle
2 SUPERCRITICAL RANKINE CYCYLE
6-82.1Supercritical technology
2.2 Efficiency
2.3 Definition
3 DESIGN AND WORKING
9-10
3.1 Boiler Design
i. Boiler shell
3.2 Working
4 MATERIAL SELECTION
11-134.1 Metallurgical Problems
4.2 Materials used
5 SUPERCRITICAL BOILERS
14-155.1 A typical Supercritical Boilers
5.2 Super and Sub Critical Boilers (comparative study)
6 ADVANCE IN SC TECHNOLGY AND FUTURE IN INDIA
166.1 Natural Gas Production with a Supercritical Geothermal
Power
7 CONCLUSION
17
8 REFERENCES 18
6. VI
ABSTRACT
This paper reviews the major technical and performance aspects of a coal fired plan using
the supercritical technology. These include the turbine-generator set, the once-through
boiler, and operational issues such as load change, fuel flexibility, and water. Reviewing
the possibilities for the design and manufacture of components for supercritical-fired
plants in developing countries, the paper notes that the differences between sub critical
and supercritical power plants are limited to a relatively small number of components;
primarily the feedwater pumps and the high pressure feedwater train equipment. All of
the remaining components, common both types of plants, can be manufactured in
developing countries. The paper concludes with a review of the Schwarze Pumpe - the
world's largest supercritical lignite fired steam power plant.The primary purpose of the
study is to assess whether supercritical thermalplant technology is a proven and mature
commercial technology and whether .They operate at supercritical pressure. In contrast to
a "subcritical boiler", a supercritical steam generator operates at such a high pressure
(over 3,200 psi or 22 MPa) that actual boiling ceases to occur, the boiler has no liquid
water - steam separation. There is no generation of steam bubbles within the water,
because the pressure is above the critical pressure at which steam bubbles can form. It
passes below the critical point as it does work in a high pressure turbine and enters the
generator's condenser. This results in slightly less fuel use and therefore less greenhouse
gas production. The term "boiler" should not be used for a supercritical pressure steam
generator, as no "boiling" actually occurs in this device.
7. VII
1 INTRODUCTION
1.1 Basic Rankine Cycle:
The Rankine cycle is the oldest functional heat cycle utilized by man. The
Rankine cycle is the very a basic vapor power cycle which is adopted in all the
thermal power plants. It is a four step process (Figure 1.1) which involves the
heating of the working fluid to its saturation temperature and vaporizing it
isothermally, expanding the vapor on a turbine (work cycle), condensing the
steam isothermally to the liquid phase and pumping it back to the boiler.
Figure 1.1.1 Basic Rankine Cycle
Figure 2 represents the temperature-entropy diagram for the simplest version of
the Rankine cycle. Although this simple version is rarely used it gives a very clear
and simple picture on the working of the cycle.
Process 1-2 is the pumping of the working fliud (water) into the boiler
drum. The power required is derived from the overall power developed. Process
2-3 is the heating of the water upto its saturation temperature (100°C at 1 atm
pressure for water) is reached and then isothermal heating of the water where the
8. VIII
phase change from liquid to vapor occurs. Points 3 lie on the saturated vapor line.
The steam here is completely dry. Process 3-4 is the adiabatic expansion of the
vapor/steam on the turbine to obtain mechanical work. It is an isentropic process.
The temperature of the steam is reduced and it falls below the saturated vapor
line. The dryness fraction is reduced to less than one and a mixed liquid vapor
phase is present. Process 4-1 is the condensation process. This mixture is
condensed in a condenser isothermally and brought to the liquid phase back to the
pump.
FIGURE 1.1.2 Temperature vs. Entropy diagram for Rankine cycle
The steam is however, usually, superheated so as to obtain more work output.
Increasing the superheat to greater extent would lead to more work output.
However the energy spent in superheating the fuel is also high. The overall effect
is an increase in the thermal efficiency since the average temperature at which the
heat is added increases. Moisture content at the exit of the steam is decreased as
seen in the figure 1.3.
Superheating is usually limited to 620°C owing to metallurgical considerations.
9. IX
Figure1.1.3 Rankine cycle with superheating
1.2 Energy Analysis of the Rankine Cycle:
All four components in the Rankine Cycle (pump, boiler, turbine and
condenser) are steady flow devices and thus can be analyzed under steady flow
processes. K.E and P.E changes are small compared to work and heat transferred
and is thereby neglected.
Thus the steady flow equation (per unit mass) reduces to:
Q+hini = W+hfinal
Boiler and condenser do not involve any work and pump and turbine are assumed
to be isentropic. The conservation of Energy relation for each device is expressed
as follows:
Steam turbine:
As the expansion is adiabatic (Q=0) and isentropic (S3=S4), then,
W3-4=Wturbine= (h3-h4) kJ/kg
10. X
Condenser:
Heat rejected in the condenser, Q4-1+h4=h1+W4-1
Since W4-1=0, Q4-1=h1-h4
Thus,
Q4-1=-(h4-h1) kJ/kg
Pump:
Work required to pump water:
Wpump=h1-h2 kJ/kg (-ve work)
Boiler:
Heat added in boiler:
Q2-3=h3-h2 kJ/kg=h3-h1-Wpump kJ/kg
Thus, the Rankine Efficiency=Work done/Heat added
= (h3-h4-Wp) / (h3-h1-Wp)
Neglecting feed pump work as it is very small compared to other quantities, the
efficiency reduces to:
ηrankine= (h3-h4) / (h3-h1).
1.3 Factors increasing the Rankine Efficiency:
i. Lowering the condenser pressure:
Lowering the condenser pressure would lead to the lowering of
temperature os steam. Thus for the same turbine inlet state, more work is obtained
at lower temperatures.
11. XI
This method though cannot be extensively used as it reduces the dryness
fraction x of the steam. This is highly undesirable as it decreases the turbine
efficiency is reduced due to excessive erosion of the turbine blades.
ii. Superheating the steam to high temperature:
There is an increase in the work output if superheating of steam is done. It
increases the thermal efficiency as the average temperature at which heat is added
increases.
There is also another benfit of superheating; the steam at the exit of the
turbine is drier than in case of non superheated steam.
iii. Increasing the boiler pressure:
Increasing the boiler pressure raises the average temperature at which heat
is added and thereby increases the theramal efficiency. However the dryness
fraction decreases for the same exit temperature of the boiler. This problem can be
solved by employing reheating procedure. If however the boiler pressure is raised
to supercritical point greater efficiency is obtained as the latent heat absorbed
during phase change is reduced to zero.
12. XII
2 SUPERCRITICAL RANKINE CYCYLE
2.1 Supercritical technology:
When temperature and pressure of live steam are increased beyond the
critical point of water, the properties of steam will change dramatically. The
critical point of water is at 374 °C and 221.2 bar (218 atm), Figure 2.1, and it is
defined to be the point where gaseous component cannot be liquefied by
increasing the pressure applied to it. Beyond this critical point water does not
experience a phase change to vapor, but it becomes a supercritical fluid.
Supercritical fluid is not a gas or liquid. It is best described to be an intermediate
between these two phases. It has similar solvent power as liquid, but its transport
properties are similar to gases.
Figure 2.1.1 Phase diagram of water
2.2Efficiency:
The Rankine cycle can be greatly improved by operating in the
supercritical region of the coolant. Most modern fossil fuel plants employ the
13. XIII
supercritical Rankine Steam Cycle which pushes the thermal efficiency of the
plant (see equation 4) into the low to mid 40% range.
ηsupercritical = (h2-h1-h3+h4 )/( h2-h1) -(eqn 4)
2.2 Definition:
Figure 2.2.1 T-S diagram for supercritical Rankine cycle
For water, this cycle corresponds to pressures above 221.2 bar and
temperatures above 374.15°C (647.3 K). The T-S diagram for a supercritical cycle
can be seen in Figure 6. With the use of reheat and regeneration techniques, point
3 in Figure 2.1, which corresponds to the T-S vapor state of the coolant after it has
expanded through a turbine, can be pushed to the right such that the coolant
remains in the gas phase. This simplifies the system by eliminating the need for
steam separators, dryers, and turbines specially designed for low quality steam.
14. XIV
Material Concerns:
The primary concern with this cycle, at least for water, is the material
limits of the primary and support equipment. The materials in a boiler can be
exposed to temperatures above their limit, within reason, so long as the rate of
heat transfer to the coolant is sufficient to “cool” the material below its given
limit. The same holds true for the turbine materials. With the advent of modern
materials, i.e. super alloys and ceramics, not only are the physical limits of the
materials being pushed to extremes, but the systems are functioning much closer
to their limits. The current super alloys and coatings are allowing turbine inlet
temperatures of up to 700°C (973 K). the fourth generation super alloys with
ruthenium mono-crystal structures promise turbine inlet temperatures up to
1097°C (1370 K). Special alloys like Iconel 740, Haynes 230, CCA617, etc. are
used.
The metallurgical challenges faced and solutions:
Normal Stainless steel proves of absolutely no use in building SC and USC
Boilers.
The high temperature and pressure in the boiler induce huge amount of stresses
and fatigue in the materials. Also chances of oxidation are very high at such high
temperature and pressure.
To resist these stress levels and oxidation different advanced materials and alloys
should be introduced.
Also they should me machinable and weldable. This is a great metallurgical
challenge.
15. XV
3 DESIGN AND WORKING
3.1 Boiler Design:
The design of Super and Ultra supercritical boilers (also called as Benson
Boiler) is very critical as the working pressures of these boilers are very high. The
boiler shells, the economizer unit, super heaters, air preheaters are specially
designed. Their location is also of great significance.
i. Boiler shell:
As shown in the figure 3.1 the geometry of the boilers and the
configuration of the inlets determine the recirculation pattern inside boiler. The
intensive recirculation created in the symmetric boiler results in a more uniform
temperature field, lower temperature peaks, moderate oxygen concentration and
complete burnout of the combustible gases and char
Fig 3.1.1 Predicted Recirculation inside the combustion chamber
Table 3.1 lists the peak temperatures and burnout for designs A, B and C. the table also
lists the standard deviations of the predicted temperature and oxygen fields. The lowest
values for C indicate the higher degree of homogeneity. Thus the symmetrical boiler
seems to be the most suitable design.
16. XVI
ii. Location of burners:
The number of burners in the boiler shell is also of prime importance.
Amongst all of them the downfired boilers are most suitable and advantageous.
Table 3.2 gives a clear idea.
iii. Boiler dimensions:
One of the most important advantages of HTAC applications are high heat
fluxes. Thus, compact combustion chambers can be built and the investment costs
can be lowered. The fourth calculation series was carried out in order to find the
combustion chamber dimensions which can, on one hand, ensure an efficient heat
exchange between combustion gas and water/steam mixture and on the other
hand, ensure high values of firing density. Three different sizes are tested and
they are named in as the small boiler, the medium size boiler and the large boiler
.It has been observed (see Table 3.3) that the small boiler is too short. At the top a
region of high temperatures exists and its enthalpy cannot be efficiently used. On
the contrary, in the large boiler although the heat fluxes areuniform, they are two
times lower than in the medium size boiler. Therefore, the medium size boiler
configuration is chosen for further investigations.
Small boiler Medium size boiler Large boiler
Firing Density
kW/m3
774 238 89
Outlet temperature,
K
1805 1558 1299
Table3.1.1 Results of the boiler size determination
3.2 Working:
As already discussed, the working of Supercritical Boilers is similar to the
working of sub-critical boilers. It works on the supercritical rankine cycle. Most
supercritical boilers are being run at operating pressures above of 235 bars. The
working of ultra supercritical boilers has operating pressures above 273 bars
17. XVII
4 MATERIAL SELECTION
4.1 Metallurgical Problems:
The available materials today like stainless steel which are usually used
for boiler parts are not suitable for SC and USC boilers. They do not have the
enough creep strength to resist the high pressure. Also there is high rate of
oxidation at such high temperature and pressures which are beyond the capability
of these materials to resist. Capable, qualified materials must be available to the
industry to enable development of steam generators for SC steam conditions.
Major components, such as infurnace tubing for the waterwalls, superheater/
reheater sections, headers, external piping, and other accessories require
advancements in materials technology to allow outlet steam temperature increases
to reach 760°C (1400F). Experiences with projects such as the pioneering Philo
and Eddystone supercritical plants and the problems with the stainless steel steam
piping and superheater fireside corrosion provided a valuable precautionary
lesson for SC development. Industry organizations thus recognized that a
thorough program was required to develop new and improved materials and
protection methods necessary for these high temperature steam conditions.
4.2 Materials used:
The materials used should be sustainable to the very high pressure being
developed and should not get oxidized due to the very high temperature. Different
high temperature materials are being used like 9 to 12% ferritic steels T91/P91,
T92/P92, T112/P122 steel, Advanced Austenitic alloys TP347, HFG, Super 304,
Nickel and chrome-nickel super alloys like Inconel 740.
Table 4.2 gives a very brief idea about the boiler materials used for
different parts of the boiler.
18. XVIII
Heat surface Tube material Header material
Economiser SA-210 C SA-106 C
Furnace Walls SA-213 T12 SA-106 C
Super
heater/Reheater
SA-213 T12
SA-213 T23
SA-213 TP 304H
SA-213
TP347HFG
SUPER 304H
SA-335 P12
SA-335 P91
SA-335 P911
Steam Piping SA 335 P91
Table 4.2.1 Materials for different boiler parts
The materials for the other parts of the power plant (like turbine) also must be
sustainable for the super critically heated steam. The following table gives a detail idea
on the turbine materials of a plant operating on a supercritical cycle. (Table 4.3)
19. XIX
Table 4.2.2 Materials for other parts
The following figures show some of the materials used for SC and USC boilers. Iconel
740 is widely used for steam pipings in almost all of them.
Figure 4.1 TP347HFG Figure 4.2 Iconel 740
Component 1,050° F 1,150 °F 1,300° F 1,400 °F
Casings
(shells, valves,
steam chests,
nozzles)
CrMoV (cast)
10CrMoVMb
9–10% Cr (W)
12CrW (Co)
CrMoWVNbN
CF8C-
Plus
CCA617
Inconel
625
Nimonic
263
CCA617
Inconel
740
CF8C-
Plus
Bolting 422
9–12%
CrMoV
Nimonic 80A
9–12% CrMoV
CrMoWVNbN
Nimonic
105
Nimonic
115
Waspaloy
Nimonic
105
Nimonic
115
U700
Rotors/Discs 1CrMoV
12CrMoVNbN
9–12 % CrWCo
12CrMoWVNbN
CCA617
Inconel
625
CCA617
Inconel
740
Nozzles/Blades 422
10CrMoVNbN
9–12% CrWCo
10CrMoVCbN
Wrought
Ni-based
Wrought
Ni-
based
20. XX
5 SUPERCRITICAL BOILERS
5.1 A typical Supercritical Boilers:
Largest CFB and first supercritical CFB sold to date is the Lagisza 460 MWe
unit Ordered by Poludniowy Koncern Energetyczny SA (PKE) in Poland. The design is
Essentially complete with financial closing expected in the first quarter of 2006 at
which time Fabrication and construction will commence. The largest capacity units in
operation today are the two (2) 300 MWe JEA repowered units which were designed to
fire any Combination of petroleum coke and bituminous coals. The physically largest
Foster Wheeler boilers in operation are the 262 MWe Turow Units 4, 5, and 6 which
were designed to fire a high moisture brown coal. The design and configuration of
these units with Compact solids separators and INTREX™ heat exchangers were used
as the basis for the Lagisza design as well as for this study. The Lagisza design was
adjusted to accommodate a typical bituminous coal and the steam cycle.
Figure 5.1.1 The Lagisza 300 MWe plant in Pola
21. XXI
5.2 Super and Sub Critical Boilers (comparative study):
There are many advantages of super critical boilers over normal
subcritical boilers, the prime advantage being the increased efficiency and reduced
emissions. There are many more advantages like no need of steam dryers, higher
operating pressures leading to more work output etc.
It is thus very important to have a comparative study of both the
boilers.
Table 5.2.1 Comparison of sub and supercritical boilers
Technology Efficiency (%) Steam
pressure/temperature
Typical emissions
Ultra Supercritical
33–35
>242 bar and
593.33°C
SO2-0.408 kg/MHh
NOx-0.286
kg/MWh
CO2-0.96 T/MWh
Supercritical
36–40
>221.2 bar and
537°C
SO2-0.431 kg/MHh
NOx-0.304
kg/MWh
CO2-1.02 T/MWh
Subritical
42–45
165 bar 537°C SO2-0.445 kg/MHh
NOx-0.31 kg/MWh
CO2-1.02 T/MWh
22. XXII
6 ADVANCE IN SC TECHNOLGY AND FUTURE IN INDIA
6.2 Supercritical Boilers in India:
There haven’t been any supercritical boilers in use in India so far. The European
countries, USA, Japan have been using supercritical technology since the last two
decades. However, there are upcoming projects to build power plants working under
the supercritical technology in India.
The National Thermal Power Corporation (NTPC) had entrusted a techno
economic study to M/s EPDC for super-critical Vs Sub-critical Boilers for their
proposed Sipat STPS (4x500 MW) in Madhya Pradesh.
M/s EPDC has recommended that a first step to the introduction of super-
critical technology, the most proven steam conditions may be chosen and the most
applicable steam conditions in India shall be 246 kg/cm2
, 538° C/566° C. With these
steam parameters, M/s EPDC has estimated that the capital cost for a supercritical
power station (4x500 MW) shall be about 2% higher than that of sub-critical power
plant but at the same time the plant efficiency shall improve from 38.64% to 39.6%.
Being a pit head thermal power project, the saving in fuel charges is not justified by
increase in fixed charges.
Here are some upcoming projects in India:
North Karanpura, Jharkhand – 3x660 MW
Darlipali, Orissa – 4x800 MW
Lara, Chattisgarh – 5x800 MW
Marakanam, Tamilnadu – 4x800 MW
Tanda-II, Uttar Pradesh - 2x660 MW
Meja, Uttar Pradesh - 2x660 MW
Sholapur – 2x660 MW
23. XXIII
New Nabinagar-3x660 MW
Many more projects including 800 MW ultra super critical units under
consideration
7 CONCLUSION
The supercritical Rankine cycle, in general, offers an additional 30% relative
improvement in the thermal efficiency as compared to the same system operating in the
subcritical region. The cycle has been successfully utilized in fossil fuel plants but the
current available materials prohibit reliable application of the supercritical cycle to
nuclear applications. There is much work to be done in order to advance materials to
the point where they will be able to reliably withstand the stresses of a supercritical
environment inside a nuclear reactor for a designed life span of 60 years.
Supercritical boiler technology has matured, through advancements in design
and materials. Coal-fired supercritical units supplied around the world over the past
several years have been operating with high efficiency performance and high
availability.
24. XXIV
REFERENCES
1. “Design Aspects of the Ultra-Supercritical CFB Boiler”; Stephen J.
Goidich, Song Wu, Zhen Fan; Foster Wheeler North America Corp.
2. “Novel conceptual design of a supercritical pulverized coal boiler utilizing
high temperature air combustion (HTAC) technology”; Natalia Schaffel-
Mancini, Marco Mancini, Andrzej Szlek, Roman Weber; Institute of
Energy Process Engineering and Fuel Technology, Clausthal University of
Technology, Agricolastr. 4, 38678 Clausthal-Zellerfeld, Germany; 6
February 2010.
3. “Supercritical (Once Through) Boiler Technology”; J.W. Smith, Babcock
& Wilcox, Barberton, Ohio, U.S.A.; May 1998.
4. “Steam Generator for Advanced Ultra-Supercritical Power Plants 700 to
760°C”; P.S. Weitzel; ASME 2011 Power Conference, Denver, Colorado,
U.S.A; July 12-14, 2011.
5. “Supercritical boiler technology for future market conditions”; Joachim
Franke and Rudolf Kral; Siemens Power Generation; Parsons Conference;
2003.
6. “Steam Turbine Design Considerations for Supercritical Cycles”; Justin
Zachary, Paul Kochis, Ram Narula; Coal Gen 2007 Conference;1-3
August 2007.
7. “Technology status of thermal power plants in India and opportunities in
renovation and modernization”; TERI, D S Block, India Habitat Centre,
Lodi Road, New Delhi – 110003.
8. “Applied Thermodynamics”; Dr. H.N Sawant; January 1992; revised July
2004.
9. “http://en.wikipedia.org/wiki/Boiler#Supercritical_steam_generator”