POWER March 2020 - 34

GAS POWER
Winning Operations, Maintenance,
Environmental, Safety, and
Technical Solutions
The Combustion Turbine Operations Technical Forum (CTOTF) recently announced
the winners of the 2nd annual CTOTF/POWER Innovation Excellence awards, which
recognize outstanding performance in various categories. Exelon Generation,
Oglethorpe Power Corp., NV Energy, and IHI Power Services Corp. were all recognized
for notable projects.
Aaron Larson
T
he Combustion Turbine Operations
Technical Forum (CTOTF) is a membership
organization of combustion
turbine owners and operators. CTOTF's
user-defined mission is to be the premier
forum for the exchange of information and
experiences related to the design, operation,
and maintenance of combustion turbine
and combined cycle power plants,
and to provide a collective voice for its
members to express issues and concerns.
The group, in association with POWER,
recently announced the winners of its
annual Innovation Excellence awards
program. Selections were made in five
categories: operational, technical, maintenance,
environmental stewardship,
and safety process areas.
Operational Excellence
In the operations category, Exelon's Mystic
Generating Station in Charlestown,
Massachusetts, was recognized for successful
windscreen projects completed
on its Units 8 and 9 air-cooled condensers
(ACCs). According to Plant Manager Brian
Pettenati, the projects were necessary to
ensure the units could reliably operate at
maximum capacity during the summer.
" On hot, windy days, we had to derate
the units due to a reduction in ACC
efficiency, " Pettenati explained. " We
needed something that would stop hot
air from recirculating from the top of the
ACC back to the suction of the fans, and
we wanted to eliminate the wind-tunnel
effect under the ACC, which tended to
stall the natural air flow to the fans. "
Pettenati asked Mike Brown, Exelon's
technical manager for the Northeast region,
to find a solution. Brown tasked
Ying Ng, senior site engineer, with managing
the project. Ng did some digging
34
1. Windscreens were installed under the Mystic 8 and 9 air-cooled condensers to minimize
de-rates on hot, windy summer days. Courtesy: Exelon Generation
and identified a windscreen solution offered
by UK-based Galebreaker Industrial.
So, Galebreaker and its subcontractor,
Ergon Research, were brought in to
study the Mystic site.
The team analyzed the topography and
building layout, then used computational
fluid dynamic models to determine how
different wind conditions and other characteristics
affected ACC performance. Once
the problem was completely understood,
Galebreaker proposed the installation
of polyvinyl chloride (PVC) windscreens,
which are 75% solid and 25% permeable.
Ng sat down with the structural engineer
and studied the design to determine
the load the ACC structure would
need to support with new windscreens
installed. Some structures would require
enhancements to handle the burden.
" We had to strike the right balance bewww.powermag.com
tween
maximizing the effectiveness of
the screens while minimizing requirements
to add new support structures to
manage installation costs, " Ng said.
The most-effective layout was found
to be a cruciform pattern of windscreens
installed under the fans (Figure 1). Ultimately,
material was fitted around the
perimeter of the ACC along the top of
the understructure.
" The windscreens work, " Pettenati
said. " Last summer, when weather conditions
would have predicted a problem
for us in the past, our ACCs continued to
perform well. "
And the improvement is paying dividends.
Pettenati said there were 368
hours with wind speeds greater than 10
mph and temperatures greater than 85F
in 2018, and 217 hours exceeding those
thresholds in 2019. Based on the average
POWER | March 2020
http://www.powermag.com
POWER March 2020

Table of Contents for the Digital Edition of POWER March 2020
