NYC 9/11 Public Portal Document
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the manufacturers of HRSGs to respond in
kind to ensure an overall improvement in
the integrated CC plant and handle
tougher temperature and pressure con
ditions. Triple-pressure reheat steam sys
Building tems, for example, now are offered by all
m^or HRSG manufacturers.
POWER Plants Triple-pressure steam systems yield
mil IN
lower stack temperatures than older,
dual-pressure systems because they re
cover more thermal energy from GT ex
haust That’s good for cycle efficiency,
LATIN which developers and financiers like, but
ui&inn America?
it limits the fuel choice to natural gas, say
many HRSG users. Users have found that
in the presence of even low levels of sul
fur—such as when firing No. 2 fuel oil—
stack temperatures must be kept above
330°F to avoid acid-gas corrosion.
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SANTOS CMI IS A RELIABLE
AND EXPERIENCED CONTRACTOR j Merchant
OFFERING CLIENTS IN THE POWER j
SECTOR THE FOLLOWING SERVICES: 1
n I‘ Z developers
j. r need to pay par-
/ Detail Engineering ft ticular attention
/ Procurement {
Uo HRSG oj^-
/ Construction:
I / Civil Works
^Wlng’. Issues.'y
i
Mechanical Installation
Electrical instalation Another design issue is installation of a
I damper in the HRSG exhaust stack. Many
INSTRUMENTATION & CONTROL. ; developers choose to omit the device to
reduce cost But users have found this can
shorten HRSG tube life. HRSGs without
stack dampers depressurize within a few
a hours after shutdown, meaning almost
every restart is from cold conditions. On
the typical P22 steam header, cold-start
fetigue damage may be 30 to 40 times that
caused by a hot start because of the “con
densate quench” phenomenon.
Merchant developers need to pay par
!! ticular attention to tube life, stack corro
sion, and other HRSG operating issues
because of the need for cycling capabil
ity in today’s competitive market. The
HRSG’s increased physical size, elevated
gas temperature, and tougher steam
conditions—when coupled to advanced
GTs—have also substantially increased
thermal stresses and fatigue damage, par
• I ticularly in the superheater section. HRSG
design often fails to take these increased
Contact us stresses into account, engineers say. Im
prudent operating procedures, some tak
tvww.santoscmi.com •. info-^uio.santoscmi.com en directly from suppliers’ manuals, fur
Corporoie Headquariers in Ecuador ther aggravate the situation, according to
(5932) 2503 - 632 / 2557 - 754 bofler experts. □
By Robert Swaneka'mp
40«POWERPLANT CONSTRUCTION
NYC-WTC_000141984
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