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CO2 Emissions Challenge in Japan and Siemens
AG Proposals for Sustainable Use of Modern
Turbine Technology for CO2 Reduction
CEPCI
October 26-30, 2014
Jeju island, Korea
Authors:
Wolfgang Bergemann
Siemens AG
Power Generation Services
Power and Gas
Table of Contents
1. Introduction ........................................................................ 3 2. Method................................................................................. 3 3. Modernization of the HP/IP Turbine BB 44 .................... 4 3.1 Reliability issues ................................................................. 4 3.2 Blade design ........................................................................ 4 3.3 Modernization solutions..................................................... 5 4. Modernization of the LP Turbine Type BB 73 ................ 8 4.1 Reliability issues ................................................................. 8 4.2 Blade design ........................................................................ 9 4.3 Modernization solution .................................................... 10 5. Conclusion ......................................................................... 11 6. References ......................................................................... 12 7. Disclaimer ......................................................................... 13 AL: N; ECCN: N
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1.
Introduction
After the massive tsunami tragedy in Fukushima in March 2011, Japan shut down all nuclear
power. Hence the entire existing fleet of more than 110 GW fossil fuel power plants, in
addition to the hydropower plants and some wind and solar plants, were faced with covering
the entire electricity demand. Due to this, the CO2 emissions intensity in Japan has increased.
One of the measures for environmental conservation, including countermeasures against
global warming, is modernizing fossil power plant turbines by increasing efficiency or
reducing fuel consumption at same output.
If requested, Siemens Energy can contribute toward overcoming this challenge with their
modern, state-of-the-art technology for blades, seals and casing design, especially for the fleet
built by MHI under a Westinghouse license. Based on our experiences with turbine
modernizations on Westinghouse units in the US, Mexico, Thailand and the United Kingdom
of Saudi Arabia, we can offer wide a variety of products for these MHI units combined with
low outage durations and extended maintenance intervals.
Siemens already has experience with modernizing MHI-manufactured units in Japan after
very successfully modernizing both NPP Sendai 1 & 2 turbines in 2006 and 2010.
2.
Method
One of the best methods for reducing CO2 emissions is modernizing the turbine. The success
of this approach can be guaranteed when the modernization results in a reduction of fuel
consumption while keeping same output, but achieved with a lower steam flow rate or output
improvement with same steam flow rate. A 1% efficiency improvement of a 500 MW coalfired power plant saves up to 35,000 t of carbon dioxide (CO2) per year.
Turbine modernization also remedies all known reliability issues. This can be achieved
mainly by replacing main components such as rotors and inner casings and reusing existing
outer casings. Using all of the knowledge from Westinghouse Building Block (BB) design
and the latest Siemens blade design, the target can be met. This paper uses the turbine
modernization of the HP/IP Turbine BB 44 and LP Turbine BB 73 as examples of our wide
range of capabilities and experience which describe a typical ~ 500MW unit.
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3.
Modernization of the HP/IP Turbine BB 44
3.1 Reliability issues
Based on technical knowledge and design criteria from decades ago we are now experiencing
some technical issues with units operating on a long-term basis as shown in Fig. 1.
Fig. 1
3.2 Blade design
The blade design is based on Siemens AG blade design with its famous 3DS/ DV Blades,
shown in Fig. 2, which were developed in the late nineties. This blade design has been used
for several turbine modernizations and was adopted for new apparatus designs.
All newly manufactured or erected steam turbine plants in last 15 years use this highly
efficient design.
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Fig. 2
3.3 Modernization solutions
Based on our and customer requests, Siemens has developed two different solutions. One for
base load operated units or so-called “full arc admissions” and one for load-following and
two-shift operation or a so-called “partial arc solution” shown in Fig. 3, 4, 5. Fig. 5 also
shows some expected thermodynamic numbers.
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Fig. 3
Fig. 4
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Fig. 5
The proposed solution shows feasibilities, especially for efficiency improvements which can
be converted into lower fuel consumption while keeping same output. Siemens also
developed new strategy to shorten the outage duration as a maintenance cost-saving measure.
The main driver has been the reuse of existing outer casing and pipes and extractions.
Shown here in Fig. 6:
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Fig. 6
4.
Modernization of the LP Turbine Type BB 73
4.1 Reliability issues
Based on technical knowledge and design criteria from decades ago we are now experiencing
some technical issues with units operating on a long-term basis as shown in Fig. 7. Especially
the Stress Corrosion Cracking (SCC) history is important due to the fact that Siemens has
strived to find out the root cause of the occurrence of SCC and has developed sufficient
measures to avoid SCC. Today, Siemens has gone more than 2 decades without any SCC on
rotors manufactured by Siemens.
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Fig. 7
4.2 Blade design
For our LP blade design, we use our 3DS blades for the drum stages. For the last stages L-0,
L-1 and L-2, Siemens uses a standardized stage package specifically designed and, generally
free-standing, finely-tuned L-0 blades and shrouded L-1, L-2 blades without damping wires or
snubbers. For efficiency reasons, with some specific solutions, we offer also shrouded L-0
solution. An overview of the key technologies is shown in Fig. 8.
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Fig. 8
4.3 Modernization solution
The newly developed modernization solution has been implemented more than 45 times in the
last couple of years. The most recent version of this 8.7m² rotor with 37.6 inch blade in the
last stage blade (LSB) is very successful, reliable and very efficient. As shown in Fig. 9, all
colored components were replaced by reusing existing outer casings. If the last stage blade
has a larger area or heavier weight, all interferences would be taken into account and solved
with a Design Analysis Report (DAR) which will be forwarded to customers.
Thermodynamic evaluation shows potential of up to 3 – 5 MW per LP or, again, the same
output with a lower steam flow rate.
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Fig. 9
5.
Conclusion
Modernizing aging steam turbines with state-of-the-art technologies can improve turbine
efficiency in general by five to six percent. Depending on the age of the design and operating
time this can sometimes be even higher. Combined with the chance of fixing reliability issues,
this method results in a high probability of reducing CO2 emissions as well as increasing the
service life and improving competitiveness. Due to the extension of inspection intervals up to
100,000 operating hours, maintenance costs can also be reduced.
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6.
References
Jansen, M.; Ulm, W. (1995): Modern Blade Design for Improving Steam Turbine Efficiency,
1st European Conference on Turbomachinery, Fluid Dynamic and Thermodynamic Aspects,
University Nürnberg-Erlangen
Simon, V.; Stephan, I.; Bell, R.M.; Capelle, U.; Deckers, M.; Schnaus, J.; Simkine, M.
(1997): Axial Steam Turbines with Variable Reaction Blading, Advances in Turbine
Materials, Design and Manufacturing, Proceedings of the 4th International Charles Parsons
Conference, London
Harig, T.; Oeynhausen, H.; Turbine upgrades - Economic and technical potentials for
conventional and nuclear plants; Reprint from BWK, March 2005
Siemens User Meetings and Siemens presentation materials
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7.
Disclaimer
These documents contain forward-looking statements and information – that is, statements
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