Abstract

In pursuit of flexibility improvements and extension of lifetime, a concept to prewarm steam turbines using hot air was developed. In order to further optimize the prewarming operation, an extensive numerical investigation is conducted to determine the time-dependent temperature and stress fields. In this work, the transient thermal and structural analyses of an IP 19-stage steam turbine in prewarming operation with hot air are presented. Based on the previous investigations, a hybrid finite element method (HFEM—numerical finite element method (FEM) and analytical) approach especially developed for this purpose is applied to efficiently calculate the solid body temperatures of a steam turbine in predefined prewarming scenarios. The HFEM model utilizes the Nusselt number correlations to describe the heat transfer between the hot air and the turbine components in the flow channel. These correlations were developed based on unsteady conjugate heat transfer (CHT) simulations of multistage turbine models. In addition, most of the thermal energy in turbine prewarming operation is transferred through vanes and blades. Therefore, the HFEM approach considers the thermal contact resistance (TCR) on the surfaces between vanes/casing and blades/rotor. After the calibration of the HFEM model with experimental data based on measurements of the natural cooling curve, the prewarming processes for different prewarming scenarios are simulated. Subsequently, the obtained temperature fields are imported to an FEM model in order to conduct a structural analysis, which, among other variables, includes the values and locations of highest stresses and displacements.

References

References
1.
Vogt
,
J.
,
Schaaf
,
T.
,
Mohr
,
W. F. D.
, and
Helbig
,
K.
,
2013
, “
Flexibility Improvement of the Steam Turbine of Conventional or CCPP
,” PowerGEN Europe 2013, Vienna, Austria, June 4–6.
2.
Vogt
,
J.
,
Schaaf
,
T.
, and
Helbig
,
K.
,
2013
, “
Optimizing Lifetime Consumption and Increasing Flexibility Using Enhanced Lifetime Assessment Methods With Automated Stress Calculation From Long-Term Operation Data
,”
ASME
Paper No. GT2013-95068. 10.1115/GT2013-95068
3.
Spelling
,
J.
,
Jöcker
,
M.
, and
Martin
,
A.
,
2012
, “
Thermal Modeling of a Solar Steam Turbine With a Focus on Start-Up Time Reduction
,”
ASME J. Eng. Gas Turbines Power
,
134
(
1
), p.
013001
.10.1115/1.4004148
4.
Topel
,
M.
,
Genrup
,
M.
,
Jöcker
,
M.
,
Spelling
,
J.
, and
Laumert
,
B.
,
2015
, “
Operational Improvements for Startup Time Reduction in Solar Steam Turbines
,”
ASME J. Eng. Gas Turbines Power
,
137
(
4
), p.
042604
.10.1115/1.4028661
5.
Helbig
,
K.
,
Kuehne
,
C.
, and
Mohr
,
W. F. D.
,
2014
, “
A Warming Arrangement for a Steam Turbine in a Power Plant,
” Patent No. EP2738360A1.
6.
Brilliant
,
H. M.
, and
Tolpadi
,
A. K.
,
2004
, “
Analytical Approach to Steam Turbine Heat Transfer in a Combined Cycle Power Plant
,”
ASME
Paper No. GT2004-53387. 10.1115/GT2004-53387
7.
Moroz
,
L.
,
Frolov
,
B.
, and
Kochurov
,
R.
,
2016
, “
Steam Turbine Rotor Transient Thermo-Structural Analysis and Lifetime Prediction
,”
ASME
Paper No. GT2016-57652. 10.1115/GT2016-57652
8.
Moroz
,
L.
,
Doerksen
,
G.
,
Romero
,
F.
,
Kochurov
,
R.
, and
Frolov
,
B.
,
2017
, “
Integrated Approach for Steam Turbine Thermo-Structural Analysis and Lifetime Prediction at Transient Operations
,”
ASME
Paper No. GT2017-63547. 10.1115/GT2017-63547
9.
Rzadkowski
,
R.
,
Lampart
,
P.
,
Kwapisz
,
L.
,
Szymaniak
,
M.
, and
Drewczynski
,
M.
,
2010
, “
Transient Thermodynamic, Thermal and Structure Analysis of a Steam Turbine During Its Start-Up
,”
ASME
Paper No. GT2010-22813. 10.1115/GT2010-22813
10.
Pusch
,
D.
,
Voigt
,
M.
,
Vogeler
,
K.
,
Dumstorff
,
P.
, and
Almstedt
,
H.
,
2016
, “
Setup, Validation and Probabilistic Robustness Estimation of a Model for Prediction of LCF in Steam Turbine Rotors
,”
ASME
Paper No. GT2016-57321. 10.1115/GT2016-57321
11.
Marinescu
,
G.
, and
Ehrsam
,
A.
,
2012
, “
Experimental Investigation Into Thermal Behavior of Steam Turbine Components—Part 2: Natural Cooling of a Steam Turbines and the Impact on LCF Life
,”
ASME
Paper No. GT2012-68759. 10.1115/GT2012-68759
12.
Marinescu
,
G.
,
Sell
,
M.
,
Ehrsam
,
A.
, and
Brunner
,
P. B.
,
2013
, “
Experimental Investigation Into Thermal Behavior of Steam Turbine Components—Part 3: Startup and the Impact on LCF Life
,”
ASME
Paper No. GT2013-94356. 10.1115/GT2013-94356
13.
Marinescu
,
G.
,
Stein
,
P.
, and
Sell
,
M.
,
2014
, “
Experimental Investigation Into Thermal Behavior of Steam Turbine Components—Part 4: Natural Cooling and Robustness of the Over-Conductivity Function
,”
ASME
Paper No. GT2014-25247. 10.1115/GT2014-25247
14.
Toebben
,
D.
,
Luczynski
,
P.
,
Diefenthal
,
M.
,
abd S. Reitschmidt
,
M. W.
,
Mohr
,
W. F. D.
, and
Helbig
,
K.
,
2017
, “
Numerical Investigation of the Heat Transfer and Flow Phenomena in an IP Steam Turbine in Warm-Keeping Operation With Hot Air
,”
ASME
Paper No. GT2017-63555. 10.1115/GT2017-63555
15.
Łuczyński
,
P.
,
Töebben
,
D.
,
Wirsum
,
M.
,
Mohr
,
W. F. D.
, and
Helbig
,
K.
,
2017
, “
Modeling of Warm-Keeping Process With Hot Air in Steam Turbines
,”
J. Power Technol.
,
97
(
5
), pp.
416
428
.http://papers.itc.pw.edu.pl/index.php/JPT/article/view/1270
16.
Toebben
,
D.
,
Hellmig
,
A.
,
Luczynski
,
P.
,
Wirsum
,
M.
,
Mohr
,
W. F. D.
, and
Helbig
,
K.
,
2018
, “
Analytical Heat Transfer Correlation for a Multistage Steam Turbine in Warm-Keeping Operation With Air
,”
ASME J. Eng. Gas Turbines Power
,
141
(
1
), p.
011013
.10.1115/1.4040717
17.
Luczynski
,
P.
,
Toebben
,
D.
,
Wirsum
,
M.
,
Mohr
,
W. F. D.
, and
Helbig
,
K.
,
2018
, “
Unsteady Conjugate Heat Transfer Investigation of a Multistage Steam Turbine in Warm-Keeping Operation With Hot Air
,”
ASME J. Eng. Gas Turbines Power
,
141
(
1
), p.
011005
.10.1115/1.4040823
18.
Toebben
,
D.
,
Schulte
,
H.
,
Luczynski
,
P.
,
Wirsum
,
M.
,
Mohr
,
W. F. D.
,
Leidich
,
F. U.
, and
Helbig
,
K.
,
2018
, “
Experimental Investigation of the Oxidation Influence on the Thermal Contact Resistance at the Blade-Rotor-Connection in a Steam Turbine
,”
International Heat Transfer Conferences (IHTC)
,
Charlotte, NC
,
June 26–30
, Paper No. GT2017-63547.
19.
Marinescu
,
G.
,
Mohr
,
W. F.
,
Ehrsam
,
A.
,
Ruffino
,
P.
, and
Sell
,
M.
,
2013
, “
Experimental Investigation Into Thermal Behavior of Steam Turbine Components—Temperature Measurements With Optical Probes and Natural Cooling Analysis
,”
ASME J. Eng. Gas Turbines Power
,
136
(
2
), p.
021602
.10.1115/1.4025556
20.
Toebben
,
D.
,
Luczynski
,
P.
,
Wirsum
,
M.
,
Mohr
,
W. F. D.
, and
Helbig
,
K.
,
2017
, “
Optimized Approach for Determination of the Solid Temperature in a Steam Turbine in Warm-Keeping-Operation
,”
International Symposium on Transport Phenomena and Dynamics of Rotating Machinery (ISROMAC)
,
Honolulu, HI
.
You do not currently have access to this content.