POWER June 2013 - 34

HEAT RECOVERY STEAM GENERATORS
The effect of the shutdowns must be included
in the assessment of the total damage
for each cycle type investigated. In summing
the fatigue damage per cycle associated with
each type of startup, assumptions must be
made about the nature of each corresponding
shutdown. There is a significant difference
in the damage per cycle for smooth versus
severe shutdown. As a part of this work, several
different shutdown assumptions were
evaluated, including the following conservative
cases. The " conservative case " assumes
that each shutdown is as severe as the startup.
Alternatively, a " realistic severe case " was
examined, where 75% of the shutdowns are
severe and 25% are smooth. This analysis
focused on the effects of the cold and warm
starts, neglecting the fatigue life contributions
of the hot restarts and load fluctuations.
The top portion of Table 2 presents the
results of the " realistic severe case. " The
predicted component life, under the assumption
that shutdowns are 75% severe and 25%
smooth, are shown. The bottom portion of
Table 2 reflects the " conservative case, "
which shows a corresponding predicted
component life under the assumption that all
shutdowns are as severe as the startups. The
life shown in these tables corresponds to the
Table 2. Fatigue life. The analysis results show the component remaining life of the drumriser
connection under " realistic severe " and " conservative " operating scenarios. Note the
sensitivity of the fatigue life of the component to the analysis assumptions. Temperature and
thermal stress calculations obtained by the finite element analysis were post-processed to determine
the fatigue life of the selected components. The analysis assumes that advanced HRSG
controls are used to reduce startup time. Source: Foster Wheeler North America Corp.
Startup case
200F/hr cold and warm
300F/hr cold and warm
200F/hr cold and warm
300F/hr cold and warm
Remaining component life
(years)
Minimum reduction in startup
time (%)
Realistic case: 100% accelerated starts; 75% severe/25% smooth shutdowns
33.7
32.6
Conservative case: 100% accelerated starts; 100% severe shutdowns
26.3
25.5
time when total fatigue damage equals 100%
and crack initiation (leading to tube failure)
is predicted. It should be noted, however, that
ASME design fatigue curves, which are the
basis for this analysis, include an additional
safety margin to account for material property
variations.
The fatigue life predictions show that
an acceptable component life is achievable
even with accelerated HRSG startup. After
adding more advanced HRSG controls for
9.7
24.7
9.7
24.7
the HRSG, the plant startup time was reduced
by up to a third with an acceptable
component life. ■
-Horst Hack (horst_hack@fwc.com),
Zhen Fan (zhen_fan@fwc.com), and
Andrew Seltzer (andrew_seltzer@fwc.
com) are with Foster Wheeler North
America Corp., Perryville Corporate Park,
Hampton, N.J. Javier Alvarez (francisco.
alvarez@fwes.fwc.com) is with Foster
Wheeler ES, Madrid, Spain.
TAVAZZANO - HRSG for Power
Plant - Italy
Porto CORsini - hrsg
for Power Plant - Italy
FESSENHEIM - Feedwater Heater
for CNPE - France
SIDI KRIR - Steam Surface
Condenser - Egypt
STF S.p.A.
Via Robecco, 20
BWE
20013 Magenta (MI) Italia
Tel: +39 02 972091
Fax: +39 02 9794977
www.stf.it
e-mail: stf@stf.it
Burmeister & Wain Energy A/S
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DK-2800 Kgs. Lyngby - Denmark
Tel: +45 39 45 20 00
Fax: +45 39 45 20 05
www.bwe.dk
e-mail: info@bwe.dk
BWE Energy India Pvt. Ltd
No. 43, KB Dasan Road
Teynampet
Chennai - 600 018
TamilNadu, India
Tel: +91 44 24 32 8101/2
Fax: +91 44 24 32 8103
e-mail: info@bweenergy.in
Heat Recovery
Steam Generators
STF S.p.A.
Via Robecco, 20
STF S.p.A.
Via Robecco, 20
STF S.p.A.
Via Robecco, 20
20013 Magenta (MI) Italia
Tel: +39 02 972091
Fax: +39 02 9794977
www.stf.it
e-mail: stf@stf.it
e-mail: stf@stf.it
e-mail: stf@stf.it
20013 Magenta (MI) Italia
Tel: +39 02 972091
Fax: +39 02 9794977
www.stf.it
20013 Magenta (MI) Italia
Tel: +39 02 972091
Fax: +39 02 9794977
www.stf.it
BWEBWE
BWE
Burmeister & Wain Energy A/S
Lundtoftegårdsvej 93A
DK-2800 Kgs. Lyngby - Denmark
Tel: +45 39 45 20 00
Fax: +45 39 45 20 05
www.bwe.dk
e-mail: info@bwe.dk
e-mail: info@bwe.dk
e-mail: info@bwe.dk
Burmeister & Wain Energy A/S
Lundtoftegårdsvej 93A
DK-2800 Kgs. Lyngby - Denmark
Tel: +45 39 45 20 00
Fax: +45 39 45 20 05
www.bwe.dk
Burmeister & Wain Energy A/S
Lundtoftegårdsvej 93A
DK-2800 Kgs. Lyngby - Denmark
Tel: +45 39 45 20 00
Fax: +45 39 45 20 05
www.bwe.dk
BWE Energy India Pvt. Ltd
No. 43, KB Dasan Road
Teynampet
BWE Energy India Pvt. Ltd
No. 43, KB Dasan Road
Teynampet
Chennai - 600 018
TamilNadu, India
Tel: +91 44 24 32 8101/2
Fax: +91 44 24 32 8103
e-mail: info@bweenergy.in
BWE Energy India Pvt. Ltd
No. 43, KB Dasan Road
Teynampet
Chennai - 600 018
TamilNadu, India
Tel: +91 44 24 32 8101/2
Fax: +91 44 24 32 8103
e-mail: info@bweenergy.in
Chennai - 600 018
TamilNadu, India
Tel: +91 44 24 32 8101/2
Fax: +91 44 24 32 8103
e-mail: info@bweenergy.in
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POWER June 2013

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