enhanced water/steam cycle for advanced combined cycle ... · enhanced water/steam cycle for...
TRANSCRIPT
-
Enhanced Water/Steam Cycle for Advanced Combined Cycle Technology
Author: Patrick Bullinger Siemens AG; Energy Solutions, Product Line Marketing Plant Solutions Power Gen Asia Bangkok, October 3 5, 2012
-
Abstract The current energy market is driven by the request of further reducing CO2 emissions. This
accelerator for eco-friendly power generation is resulting in the necessity to integrate more
renewable resources in the energy mix. The weather and daytime dependency of renewable
energy causes highly fluctuating load profiles in the grid. A back up power generation with
advantages in emissions, flexibility and low operational costs is required to ensure reliable
electricity production. The catastrophe of Fukushima in March 2011 changed the direction of
nuclear power generation in many regions. Combined cycle power plants can build a bridge
towards the future when nuclear power plants have been switched off and the integration of
renewable has been decelerated.
Due to high availability of gas resources in certain regions and further extension via liquefied
natural gas (LNG) supported by the economic growth especially in emerging countries,
combined cycle power plants are expected to play a major role in the energy mix in the future.
A new generation of gas turbines with combined cycle plant efficiencies of over 60% and
enhanced operational flexibility entered the market with commercial operation in summer 2011.
The key to implementation of those new features is overall plant optimization, since power
plants have to be designed to accommodate the new performance parameters.
A major driver for performance improvement is the optimization of the water/steam cycle in
regard of temperature and pressure. Steam temperatures far above 565C up to ~600C and
steam pressures above 170bar are used to attain highest efficiencies. These ambitious
parameters cause huge challenges in regard of boiler materials, flexibility of the boiler and water
chemistry.
Siemens is the only company to have accumulated operational experience with raised steam
parameters in the combined cycle power plant Ulrich Hartmann SCC5-8000H 1S; Irsching
Unit No.4 with a net efficiency of 60,75%.
Based on that experience this paper presents the issues to be taken into account when designing
an advanced water/steam cycle.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 1
-
Table of contents 1 Introduction ..........................................................................................................................3 2 The levers of Performance increase....................................................................................7 3 Challenges of the advanced cycle ........................................................................................9 3.1 Impact on boiler materials...............................................................................................9 3.1.1 Impact of steam side oxidation.............................................................................9 3.1.2 Spallation............................................................................................................13 3.2 Application limits of the drum type boiler ....................................................................14 3.3 Water chemistry ............................................................................................................15 4 Technical solution...............................................................................................................17 4.1 Boiler material for the EN and ASME market application ...........................................17 4.2 BENSON technology with 3 pressure Reheat............................................................18 4.3 Condensate Polishing the key element for minimized chemical wear and tear .........20 5 Operational experience - EON Ulrich Hartmann SCC5-8000H, 1S (Irsching No.4).......21 6 Summary and Outlook.......................................................................................................26 7 References ...........................................................................................................................28 8 Copyright ............................................................................................................................29
Power Gen Asia Bangkok, Oct. 3. -5. 2012 2
-
1 Introduction Todays combined cycle power plants (CCPP) have to fulfill challenging requirements in order
to comply with the boundary conditions requested by the energy politics, infrastructure and
periphery. Although these requirements differ from region to region due to specific market
environments, three major drivers can be determined. All of these requirements are necessary to
ensure a successful operation of the power plant.
- Investment
- Efficiency
- Operational flexibility
Investment Most of todays power plant projects are purely economical driven. Naturally, the investor
expects an attractive return of investment. Beside the margins generated by the revenues the
investment is a key figure. It does not mean that the lowest price will result in the most
attractive business model, as often reduced first investment result in additional cost during
operation or reduce the capabilities of the proposed solution. The whole life cycle costs of a
power plant have to be taken into account. Nevertheless, it is essential to optimize the solution
to the lowest possible invest without jeopardizing the business model of the project.
Efficiency The demand of highest efficiencies is a key requirement of todays and tomorrows combined
cycle power plants. Current developments in the energy markets are requesting fuel
consumption saving and therefore the need of higher efficiencies due to the following reasons:
1. High gas prices in some regions (especially in the Asian, European and Latin American
markets) with the consequence of high electricity production cost.
2. The further reduction of CO2 emissions in order to enable-eco friendly operation is
indispensable. The contribution of combined cycles is to reduce emissions due to operation at
higher efficiencies. To give an example, an efficiency improvement of 1.5%-pts. saves 14.700
Power Gen Asia Bangkok, Oct. 3. -5. 2012 3
-
tons of fuel gas per year while reducing CO2 emissions by 41.000 tons per year when a 600MW
combined cycle power plant will be operated at base load.
3. A very simple but decisive effect is the higher profitability during operation with higher
efficiencies. Furthermore a high efficiency results in a low merit order and increases the
probability to be dispatched.
Operational flexibility The need of operational flexibility has become more and more important in recent years and this
need is expected to continue for the mid term. To become a prime candidate of the dispatcher
todays combined cycle power plants have to be able to operate with fast fluctuating load
profiles. Fluctuating load will occur more frequently in the future due to the following reasons:
First is the above mentioned increase of renewable integration in the energy mix. The non-
availability of wind or solar energy has severe impact on the load profile.
Figure 1.1 shows the forecasts for a typical day in Germany in 2020 with low versus high wind
power feed-in. In the case of a high expected wind power input during the day as shown here, no
further fossil power generation is required during the night, i.e. when demand is low, as there is
a residual load (difference between demand and renewable feed-in) of zero or even over-
capacity (that is to say negative residual load). Compared to a day with a low wind feed-in there
is a continuous demand for about 20 GW of conventional base load capacity. The conclusion to
be drawn is that the major part of the conventional power generating capacity will probably not
be continuously required. This is the case in countries with growing renewable portfolio.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 4
-
Source: joint study Siemens and VDE, AT40 scenario, March 2011
Low wind feed-inLow wind feed-in High wind feed-inHigh wind feed-in
Peak
12 GW
23h20 GW
11h
10 GW
10h8 GW
9h2 GW
8h2 GW
6h
10 GW
-10.000
-5.000
0
5.000
10.000
15.000
20.000
75310 2232119171513119 5
11h
10h
9h
8h
6h
Peaks
Loadramps:
Average: 56 MW/min
Max.: 377 MW/min
Min.: 0,028 MW/min
ContinuousContinuous
Daily start-stop
100% daily start-stop
Up to 100% of the fossil fleet in daily start-stop operationLoad ramps of about 200MW/min to be covered
Peak LoadPeak Load
05.000
10.00015.00020.00025.00030.00035.00040.00045.00050.000
252321191715131197531
11h
10h
9h
8h
6h
Peaks
23h
2 GW
6 GW
2 GW
1 GW
2 GW
4 GW
10h
Peak
6h
9h
8h
11h
Overload
Time [h]
Res
idua
l loa
d[M
W]
Res
idua
l loa
d[M
W]
Time [h]
Figure 1.1 Residual load cycles in the year 2020 (examples of feed-in scenarios) for Germany
Second is the highly fluctuating load caused by the changing demand during peak time.
As an example for Singapore the load profile of a typical day is shown in figure 1.2. The
required load varies between 4,5GW (night time) and 6,5GW (peak). This fluctuating load has
to be captured by highly flexible combined cycle power plants. This is especially important in
Asia where more than 50% of the energy supply is generated by less flexible coal fired power
plants.
Many energy markets already require and compensate providers for short term additional power
generation. This minute reserve can be very profitable and can only be provided by highly
flexible power plants.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 5
-
Sunday Peak load:Mostly SPP and some CCPP are runing
Peak & Intermediateload:Predominantly CCPP
Weekday Peak load:SPP and CCPP areoperating
Source: Enegy Market Authority, Singapore
May 2010
6552MW
4474MW
Figure 1.2 Fluctuating load profile in Singapore Taking into account an increasing worldwide gross domestic product (GDP) and the growing
availability of natural gas through the continuous extension of natural gas grids in combination
with the uncertain outlook of nuclear power plants its not surprising that combined cycle power
plants will play a major role in the future energy mix. Considering the ASEAN region, a
compound annular growth rate (CAGR) from 2012 2017 of almost 6% is expected. LNG is
becoming worlds new gas highway of choice with a potential of 10% CAGR capacity growth
for the next 10 years. Especially for the ASEAN region with a global demand of LNG of almost
60% it clearly confirms the need of further extending of combined cycle power plants fleet.
The application of an advanced cycle supports the necessary extension of combined cycle power
plants in regard of required efficiency, operational flexibility and profitability. This paper
describes the inherent challenges to be taken into account when designing such a cycle.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 6
-
2 The levers of Performance increase
Steam turbine Water steam cycle Gas turbine
Improved sealing technologies
Optimization of blade profiles (3DS)
Increase of steam parameters Triple pressure
reheat cycle Improved heat
transfer
Increase of turbine inlet temperature
Reduction of cooling air consumption
Optimization of flow path and blade profiles
Fuel preheating
Figure 2.1 Plant efficiency improvement areas
There are several different approaches that can be used to increase efficiency of a combined
cycle power plant. As shown in figure 2.1, in addition to optimization on a component level
main driver is the optimization of the water/steam cycle.
This paper will focus on the improving combined cycle capability through changes to the
water/steam cycle, specifically increasing the steam temperature and pressure. The necessary
increase in steam parameters is only feasible due to the steady improvement of the gas turbine
and steam turbine. The constant increase of the turbine inlet temperature of the gas turbine led to
exhaust temperatures far above 600C and enabled the application of a 600C water/steam cycle.
Figure 2.2 shows the constant improvement of combined cycle efficiencies starting from 52%
efficiency with low steam parameters in 1991.
Siemens H-class combined cycle power plant technology has proven the capability to operate at
efficiency levels far above 60% today. This development was enabled via a stringent application
of total plant optimization.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 7
-
1991 1996 2001 2011SGT5-2000E SGT5-4000F SGT5-4000F SGT5-8000H
52 % Efficiency*Killingholme
2 x 470 MW, 2x(2+1)
56 % Efficiency*Didcot B1&2
702 +710 MW, 2x(2+1)
58 % Efficiency*Mainz-Wiesbaden
>400 MW, (1+1)
>60% Efficiency*Irsching 4
SCC5-8000H 1S 570 MW
Basis - 7.1 % - 10.3 % - 13.3 %Reduction of CO2 emissions
Advanced GT technology allows for significant improvement of competitiveness and serves as basis for CO2 reduction of gas fired generation
* Net efficiency achievable with this technology / project specific efficiencies may vary
Texh = 548CT/p Life steam = 516C/ 75bar
Texh = 562CT/p Life steam = 515C/ 100bar
Texh = 585CT/p Life steam = 547C/ 105bar
Texh = 640CT/p Life steam = 600C/ 171bar
Figure 2.2 Product development of CCPP The increase in steam parameters coming from 565C and 105 bar (typical SCC5-4000F
application) is a design challenge especially for the Heat Recovery Steam Generator (HRSG) for
the following three reasons:
1. Steam parameters above 565C require special attention to the use of boiler
materials.
2. Above a certain steam pressure level the natural circulation as realized in a natural
circulation drum type boiler can not be sustained anymore.
3. High pressure steam increases the challenges to mainatain feed water chemistry
within limits.
Siemens engineering has developed designs to overcome these hurdles and achieve record
breaking combined cycle efficiency.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 8
-
3 Challenges of the advanced cycle The three challenges as described in chapter 2 defined by the application of raised steam
parameters will be described in the following chapter.
3.1 Impact on boiler materials One of the most critical components of the advanced cycle is the Heat Recovery Steam
Generator (HRSG), especially the HP-superheater and IP-reheater section. To enable operation
conditions with steam temperatures of ~600C and pressures above 170bar, materials for the
critical sections need to have a combination of the following capabilities:
- sufficient creep strength behaviour at design temperature (stable microstructure)
- acceptable resistance to steam side oxidation (determined by Chrome content)
- sufficient fatigue characteristics to resist to extreme thermal cycling requirements
- acceptable cost of the design solution
3.1.1 Impact of steam side oxidation A huge challenge caused by increased steam parameters is steam side oxidation of the affected
components. Figure 3.1 provides an overview of typical tube inner and outer wall temperatures
for the HP-final superheater fintubes. Temperatures marked in green are related to clean
conditions without any oxidation layer on the tube inner wall. Temperatures marked in red
represent the case that steam side oxidation occurs. The oxidation layer on the inner wall hinders
the heat transfer due to its low thermal conductivity and results in an increase of the tube wall
temperatures. The increased middle wall temperature results in reduced strength properties and
has to be considered in the design by selection of appropriate temperature margins. Also a
respective corrosion allowance should be considered to account for the loss of tube base
material due to the oxidation.
This effect would have to be considered in the design of the respective components.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 9
-
Figure 3.1: Temperature behaviour based on steam side oxidtaion
Oxidation rate The formation of oxide scale on the tube inner wall (oxidation kinetic) is mainly driven by: - Steam temperature, tube inner wall temperature
- Material (esp. chrome content)
- Grain size (esp. austenit)
Steam temperature The influence of the steam temperature on the oxidation layer growth rate is shown in figure 3.2
for the application in the inner tube wall with the material P91. The higher the steam
temperature the higher the oxidation rate. A disproportionate increase of the oxidation layer
thickness can be seen in the temperature range of 600C which is the crucial temperature for the
advanced cycle. This effect has been evaluated and confirmed by different applications in steam
plants and has to be considered for the design of the respective components.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 10
-
Figure 3.2 Impact on oxidation layer thickness [2] Chrome content The oxidation rate is determined by the Chrome content of the material. The higher the Chrome
content the better the oxidation resistance. Figure 3.3 shows the oxidation growth behaviour for
different materials (based on a tube inner wall temperature of 600C). The chart for 9% chrome
content is representative for T91 and T92, whereby oxidation resistance of P91 is reported to be
slighly better compared to T92. The chart provided for 12% chrome steels is typical for
martensitic materials.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 11
-
Figure 3.3 Oxidation behaviour based on Chrome content [2]
A significant change in oxidation rate can be seen at a content above 12% (figure 3.4). A further
increase of the Chrome content has only slight impact on the resistance of the oxidation rate.
Below a Chrome content of 9% (e.g. P91/ T91) the oxidation rate behaviour is comparatively
poor. This effect has to be considered for the design of the respective components.
Chrome content
Oxi
datio
n ra
te
Figure 3.4 Chrome content over oxidation rate
Power Gen Asia Bangkok, Oct. 3. -5. 2012 12
-
3.1.2 Spallation The oxide scale on the tube inner surface has got different thermodynamic properties compared
to the base material. Especially the thermal expansion coefficient is different. Especially in case
of transient operation, e. g. start-up and shut-down resulting in mechanical stress between oxide
scale and base material. Above a certain thickness of the oxidation layer spallation has to be
unavoidably expected. Spallation has a major impact on the water/steam cycle due to the
following reasons:
1. Solid particle erosion due to spallation especially during start-up and shut-down
(highest strain load)
2. Material abrasion due to spalling (loss of base material, loss of strength)
3. The oxidation layer serves as protection of itself by limiting further oxidation growth.
Spallation in a certain temperature and time range results in an uncontrolled growth
behaviour of the oxide layer.
As a consequence above a certain temperature range tube materials with chrome content >12%
have to be considered to limit negative effects caused by the formation of oxide scales on the
tube inner walls.
Reference [1] Severe scale separation, cracking, and exfoliation were observed in T91 pendant reheater tubing
in a Japanese utility boiler after around 40.000 hours of operation. Separation occured at the
interface between the inner and outer layers of scale (figure 3.5).
Power Gen Asia Bangkok, Oct. 3. -5. 2012 13
-
Figure 3.5 Spallation of inner surface tube
3.2 Application limits of the drum type boiler Drum type boiler A high-pressure drum in the HRSG is one of the most critical component with regard to
limitation in the start-up and ramping procedure as a thick-walled component exposed to large
temperature gradients and high operating pressures. Fatigue damage of the drum caused by
alternating stress is increasing disproportionally with higher wall thickness.
Typical approximate values for the drums are:
Pressure level Wall thickness
180bar ~140mm --> SCC5-8000H
130bar ~100mm --> SCC5-4000F
First calculation shows, that the impact on life time for a 160 bar solution is approximately 8
times higher then for a 125 bar solution when similar load gradients are considered
Power Gen Asia Bangkok, Oct. 3. -5. 2012 14
-
From a thermodynamical point of view, another effect is restricting the application of the drum
boiler especially for increased steam pressures (figure 3.6).
The natural circulation effect is driven by the difference in density of water and steam in the
evaporator and downcomer tubes. As the difference in density decreases with the higher
pressures there is a limit for drum pressure of about 180 to 190 bar for natural circulation
boilers. In regard of a safety margin application, the practical limit will be maintained at
~170bar.
0
100
200
300
400
500
600
700
800
900
1000
0 50 100 150 200 250
Pressure [bara]
Spec
ific
Den
sity
[kg/
m3]
Density Water
Density Steam
Difference
Figure 3.6 Pressure limit for natural circulation
The pressure limitation is counter productive to the requirement of raised steam parameters as
described above. For that reason an application of a thick walled drum type HRSG is suitable
for moderate steam parameters below 170 bar and base load operation only.
3.3 Water chemistry Impurities in the water/steam cycle can lead to deposits and corrosion phenomena of the
affected components. It must be realized that this effect has negative impact on the lifetime of
the components and that efficiency of the power plant might be decreased. The Water chemistry
is a crucial topic for the successful operation of a power plant independent of the boiler type.
In a once-through boiler design the complete evaporation of the feedwater occurs within the
evaporator tubes. All salt impurities as well as corrosion products will deposit at the internal Power Gen Asia Bangkok, Oct. 3. -5. 2012 15
-
heat exchanger tube surfaces especially in the evaporation area. It is also possible that these
impurities and corrosion products will be transported into the super-heater and the steam turbine
and may entail severe damages (e.g. stress corrosion cracking).
In a drum type boiler application two different effects occur and have to be considered for the
respective design. First is the transportation of impurities due to mechanical and vaporous
carryover and the second is increasing solubility of silica at high pressure steam.
It is important that mechanical carryover is controlled and well-known for each boiler. Vaporous
carryover occurs due to the volatility of the substances present in the boiler water. The effect of
carryover is intensified with raised steam pressures.
Silica shows the highest solubility of feedwater contamination within high pressure steam
Deposits of silica caue an efficiency reduction due to increased roughness of the steam turbine
blading surface.
These two effects are intensified at raised steam parameters which is challenging for the design
of an advanced cycle.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 16
-
4 Technical solution Based on the challenges described above this chapter addresses the technical solution for the
application of raised steam parameters in the advanced cycle.
4.1 Boiler material for the EN and ASME market application To find the best possible design solution for the material of the HP-superheater and IP-reheater
heating surfaces the effects as described in chapter 3.1 have to be considered for the respective
design. A detailed design study on that topic has been performed by Siemens. The programm
target was to find the best technical solution for the application in an HRSG with 600C steam
temperatures for both the EN (former DIN) and ASME market requirements. Solutions are
identified for regions which use EN requirements and those that use ASME requirements.
Material choice for EN Material VM12-SHC from Vallourec Mannesmann has been selected for the application in the
EN market. This material has a chrome content of 12% and is considered the best technical
solution to fulfill all requirements in regard of creep, steam side oxidation, fatigue and cost.
VM12-SHC has been applied in Siemens SCC5-8000H power plant Ulrich Hartmann (Unit
No.4; Irsching) for the high temperature superheater and reheater section up to 600C. During
design, manufacturing and installation valueable experience has been obtained for future
applications. As of August 2012 the plant is operating for more than 12.500EOH in CCPP
operation without any issues.
Material choice for ASME According to Vallourec Mannesmann the issue of a Code Case for the use of VM12-SHC within
ASME stamped boilers is still uncertain and will take a minimum of one year. Therefore VM12-
SHC cannot currently be used at this time for ASME stamped applications. VM12-SHC is the
technical solution for the EN market only.
Based on that issue and with the support of operational experience from Ulrich Hartmann power
plant (SCC5-8000H; 1S; Irsching No.4) a design study of the different feasible material
combinations has been conducted. Various sophisticated detailed design solutions have been Power Gen Asia Bangkok, Oct. 3. -5. 2012 17
-
evaluated in regard to creep, steam side oxidation, fatigue and cost. An alloy on a basis of a 18-
20% chrome content has been found as the best technical and economical solution for the
advanced cycle to meet ASME market requirements.
4.2 BENSON technology with 3 pressure Reheat The main feature of BENSON boiler technology is once-through steam generation. In this
type of boiler, the conventional separation of steam and boiling water inside a boiler drum is not
necessary. Steam is generated directly within the evaporator tubes of the boiler. As shown in
figure 4.1 the high pressure drum can be omitted and replaced by a steam separator.
Principal Diagrams of Evaporator SystemsPrincipal Diagrams of Evaporator Systems
Steam
Feed-water
Heating
Drum Boiler
Steam
Feedwater
Once-Through Boiler
Heating
Figure 4.1 BENSON vs. drum type boiler
A temperature-controlled start-up process which uses optimized high-capacity de-superheaters
to limit steam temperatures during the startup process has been developed for warm and cold
starts. This reduces thermal stress in critical components of the steam turbine.
The application of a BENSON HRSG allows an increased number of permissable starts and
cycling events over the lifetime, by reducing stress induced fatigue in the high pressure section
of the HRSG.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 18
-
Since the limiting component of the HP drum is omitted, and due to a thin walled separator
with wall thickness of only ~55mm at 180bar increased load gradients and highest operational
flexibility can be realized.
To further improve the water/steam process with regard to combined cycle efficiency, a three
pressure reheat process has been applied. Figure 4.2 shows a typical Q-T (transfered heat,
temeperature) diagram for HRSG comparing the different reheat processes in order to explain
the advantage of a three pressure reheat process.
The exhaust gas temperature limits the maximum achievable steam temperature. The exhaust
gas thermal heat defines the limit for overall heat transfer to the water/steam cycle.
The area between the exhaust gas temperature line (pink) and the corresponding water/steam
process line defines the amount of energy losses. The thermodynamical target is to reduce this
area in order to generate the highest possible heattransfer between the exhaust gas and the
water/steam cycle. This improvement can be achieved by increasing the heat exchange surface
or by the application of an improved three pressure reheat process. Due to the high cost impact
of increasing heat exchange surfaces, a theoretical optimum for the corresponding process has
been defined for the application in a three pressure reheat process.
Figure 4.2 Temperature curve of a typical Heat Recovery Steam Generator (HRSG)
The definition of economically optimized heat exchange surface is based on economical criteria
and rules the process design as well as achievable water/ steam temperature, pressure and flow
rates. As this component is of major importance for boosing efficiency and operational
Power Gen Asia Bangkok, Oct. 3. -5. 2012 19
-
flexibility this sophisticated design solution has been developed Siemens in-house on the basis
of the available experience with previous BENSON boilers. .
4.3 Condensate Polishing the key element for minimized chemical wear and tear The operation of the Condensate Polishing Plant ensures the required feedwater purity for a
once-through boiler. Because of the concept of mixed bed filter with upstream mechanical
treatment process (one way cartridge filters) the main condensate is cleaned from corrosion
products and ionic impurities. Siemens recomends to use a condensate polishing plant for once-
through boiler in order to keep the contamination of feedwater within the limits (e.g. VGB or
EPRI).
The evaporation of the drum boiler circulating water causes a continuous concentration of trace
impurities introduced by the feedwater. In order to achieve the recommended values for steam
purity and boiler water quality the operation of the boiler blow-down has to be performed. With
increased temperature and pressure the volatility of the impurities is increased and a higher
boiler water quality and respectively higher feedwater quality may be required. Therefore the
usage of a condensate polishing plant has to be considered.
Additionally the main advantages of a condensate polishing plant are:
Waiting time for steam purity is reduced (shorter start up times especially for
cold and warm starts)
Impurities concentrations will stay well beyond the critical limits
No operational limitations of the power plant
Higher flexibility
Lower blow down rates (reduced loss of water and heat)
Reduced duration of commissioning time
Minor contamination due to leakages will be removed
Power Gen Asia Bangkok, Oct. 3. -5. 2012 20
-
5 Operational experience EON Ulrich Hartmann SCC5-8000H, 1S (Irsching No.4) The Siemens combined cycle power plant Ulrich Hartmann (SCC5-8000H; 1S; Irsching No.4)
is the first power plant in commercial operation with a proven net efficiency far above 60%
(60,75% confirmed by the independent technical inspection authority TV SD). This power
plant was extended and converted to a combined cycle power plant and was restarted in January
2011. The simple cycle operation with the new H-class technology had first fire in December
2007.
The single shaft design was developed in the early 1990s and has been successfully
implemented since then in the SCC5-4000F 1S. More than 100 units using the single shaft
design are currently in commercial operation.
The H-class gas turbine design is a common development that integrates Westinghouse and
Siemens design experience and combines the best technologies out of both established product
lines to ensure a best available and reliable solution.
Siemens is the first and only manufacturer who realized the operation of a combined cycle
power plant with the application of an advanced cycle. All relevant requirements necessary for
the advanced cycle has been applied.
- raised steam parameters
- BENSON Technology with three pressure reheat
- Application of VM12- SHC for boiler materials
This overall plant optimization led to the world record net efficiency of 60,75% without
sacrificing operational flexibility. Figure 5.1 shows the plant layout of Irsching Unit No.4.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 21
-
Figure 5.1 Plant Layout of Ulrich Hartmann
BENSON Technology development and delivery by Siemens E.ONs Ulrich Hartmann combined cycle power plant is characterized by the application of the
proven BENSON design technology with a three pressure reheat process. This power plant is
the first unit in commercial operation (> 12.500 EOH and >330 starts; CCPP operation) with
raised steam parameters:
GT exhaust temperature ~625C
Life steam temperature ~600C
Reheat temperature ~600C
Life steam pressure ~170bar
This combination enables the breakthrough of highest sustained efficiency with great
operational flexibility. The once through Boiler with BENSON Technology as applied in
Irsching No.4 with all the advantages of approved design concepts is shown in figure 5.2. The
design principles are based on the proven F-class plant design with high operational experience.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 22
-
Approved Design Concept
3-Pressure with Reheat
Horizontal Arrangement, Top Supported
Cold Casing Construction
Standard Plant Arrangement Concept
Standard Process Engineering Equipment
11-Nov-201011-Nov-2010
Figure 5.2 BENSON HRSG
The application of the boiler material VM12-SHC was applied in Irsching No.4 in order to apply
the best technical solution in regard to creep, steam side oxidation, fatigue and cost.
Operational Flexibility
Although Irsching No.4 was designed and sold as a base load unit the current dispatch situation
requires a daily start/stop cycle (figure 5.3). This high fluctuating load profile can be matched
due to the high capacity of operational flexibility of this combined cycle power plant. This
advantage of exceptional flexibility required by current market environments will be described
in the following.
Figure 5.3 typical daily load profile of Irsching No.4
Power Gen Asia Bangkok, Oct. 3. -5. 2012 23
-
The application of the FACYTM (FAst CYcling) Technology facilitates an overnight shut-down
and helps further reducing CO2 emission and saving fuel cost. Figure 5.4 shows an extract of the
test results of the start-up procedure in Irsching No.4. The FACYTM technology was tested
successfully on the basis of raised steam parameters (~170bar; 600C).
0
100
200
300
400
500
600
Time [min]
0
10
20
30
40
50
60
ST speed
Plant start-up time < 30 min.
GT speed
GT ignition GT @ base load
CC full load
Turb
ine
Spee
d
Plan
t Out
put
GT load
Plant output
~50%~36%Average efficiency (time frame for conventional start)
~326 MWh~514 MWhFuel consumption (start up only)
Hot startwith FACY
conventionalhot start
~50%~36%Average efficiency (time frame for conventional start)
~326 MWh~514 MWhFuel consumption (start up only)
Hot startwith FACY
conventionalhot startload
time
Conven-tionalstart up
Improvedstart up
ImprovementImprovement
~30 min.
Figure 5.4 fast start up with FACYTM
FACYTM enables the first steam generated to be delivered directly to the steam turbine. The
shorter start-up time and the ability to utilize the steam from the very beginning improve the
formerly inefficient start-up process by 14% points. That enables the participation in the highly
Power Gen Asia Bangkok, Oct. 3. -5. 2012 24
-
profitable spot market (tertiary reserve). Table 5.5 shows a reference of successful installed
FACYTM technology in commercial operation.
Table 5.5 References of FACYTM Technology
Not of less importance is the opposite direction in regard of fast shut-down due to grid failures
or sudden oversupply of renewable (negative residual load). A fast shutdown has been validated
in Irsching Unit No.4 within less than 30 minutes. Despite a world class efficiency and power
the plant can be parked at less than 100MW (20% CCPP power) with an efficiency typical for
high end open cycle applications.
For that reason the SCC-8000H is the perfect choice for high efficient applications in all
relevant operation regimes (Peaker, Intermediate or Base Load) and the guarantee of high
operational flexibility in order to meet all necessary market requirements. .
Power Gen Asia Bangkok, Oct. 3. -5. 2012 25
-
6 Summary and Outlook There is a clear expectation that combined cycle power plants will play a major role in the
energy mix in the future. This is driven by the following factors
There is a high availability of gas resources in certain regions and the further
extension via LNG or gas grid is supported by the economic growth especially in the
emerging countries.
A drive for eco-friendly power is resulting in a need to integrate more renewable
resources, which drive the need for fast, flexible operation.
Low emissions and low operational costs demand high efficiencies.
The Optimization of the power plant as a whole unit is thereby mandatory to achieve these
ambitious targets. The application of an advanced cycle with raised steam parameters and the
application of the requested materials for highest technical loads enable the combined cycle
power plant to realize efficiencies beyond 60% while enabling fast starting, fast cycling and
dependable operation.
This paper described how this optimization has been realized in the benchmark power plant
Ulrich Hartmann, SCC5-8000H, 1S (Irsching No.4). The application of the flexible BENSON
technology with raised steam parameters to enable highest efficiencies beyond 60% is the ideal
reference for an advanced cycle.
Figure 6.1 shows the evolution of combined cycle power plants during the last 20 years. This
constant development will also be necessary for future applications and the demand of higher
efficiencies in combination with affordable electricity will further drive the combined cycle
power plant developments.
Power Gen Asia Bangkok, Oct. 3. -5. 2012 26
-
Figure 6.1Evolution of combined cycle power plants
The sophisticated design solution as applied in the power plant in Irsching No.4 means the
highest degree of reliable and proven innovation due to an integrated development of all
relevant components from one hand.
Siemens technology gives answers to the regional specific requirements and offers innovative
design concepts for combined cycle power plant applications to the customer.
A world-class efficiency with operational experience of more than 12.500 EOH; CCPP-
operation without any issues, excellent start-up and operational reliability emphasize the success
story of Irsching No. 4. These outstanding references are highly appreciated by our customers.
As of today more than 15 SGT-8000H gas turbines has been sold in the 50& 60Hz market.
Its tested, its validated, its commercially available and its running...
Power Gen Asia Bangkok, Oct. 3. -5. 2012 27
-
7 References [1] Japanese with steam oxidation of advanced heat resistant steel tubes in power boilers; N.Nishimura [2] Oxidschichtwachstum Bereich HD- Endberhitzer, Stefan Rasche, 2006-04 [3] ASME material concept for HRSG with main steam parameters of 600C/180bar; Christoph Schmitt, 2012-04 [4] Hochflexible BENSON Abhitzedampferzeuger Erfahrungen aus Irsching 4; Jan ^ Brckner, VDI Wissensforum [5] L. Balling, Dr. U. Tomschi, A. Pickard, G. Meinecke, Fast Cycling and Grid Support Capability of Combined Cycle Power Plants to optimize the Integration of Renewable Generation into the European Grid: Live examples from projects in NL, F, UK, D, PowerGen Europe, Amsterdam, June. 2010 [6] The Future Role of Fossil Power Generation; Andreas Pickard, Gero Meinecke, Power GEN [7] Beauftragung von FANP fr AHDE-Materialuntersuchung bei 600C FD fr GUD; Tanja Seibert, Rainer Hardt; AREVA NP GmbH; 2006 [8] Dr. R. Fischer, P. Ratliff, W. Fischer, SGT5-8000H Product Validation at Irsching Test Center 4 Power-Gen Asia 2008 [9] Dr. S. Abens, Dr. F. Eulitz, I. Harzdorf, M. Jeanchen, W. Fischer, R. Rudolph, P. Garbett, P. Ratliff, Planning for Extensive Validation of the Siemens H-Class Gas Turbine SGT5-8000H at the Power Plant Irsching, ASME Power Conference, July 2009, POWER2009-81082 [10] Gas Fired Power Generation Outlook to 2020; Siemens Marketing; August 2012 [11] Ein Jahr Betrieb im Ulrich-Hartmann-Kraftwerk (Irsching 4); Lothar Balling; BKW; June 2012
Power Gen Asia Bangkok, Oct. 3. -5. 2012 28
-
Power Gen Asia Bangkok, Oct. 3. -5. 2012 29
8 Copyright The content of this paper is copyrighted by Siemens AG Energy Sector and is licensed only to
PennWell for publication and distribution. Any inquiries regarding permission to use the content
of this paper, in whole or in part, for any purpose must be addressed to Siemens AG Energy
Sector directly.
1 Introduction2 The levers of Performance increase3 Challenges of the advanced cycle3.1 Impact on boiler materials 3.1.1 Impact of steam side oxidation3.1.2 Spallation 3.2 Application limits of the drum type boiler 3.3 Water chemistry4 Technical solution4.1 Boiler material for the EN and ASME market application4.2 BENSON technology with 3 pressure Reheat4.3 Condensate Polishing the key element for minimized chemical wear and tear5 Operational experience EON Ulrich Hartmann SCC5-8000H, 1S (Irsching No.4) 6 Summary and Outlook7 References8 Copyright