POWER March 2016 - 14

Using Steam Turbine
Warming Blankets to
Reduce Startup Time and
Rotor Stress
Steam turbines have to be warmed slowly
to avoid excessive differential expansion
of the various components, rotor
stress, and potentially reduced service
life. For that reason, startup times must
be extended under certain conditions to
allow gradual heating of components,
which can prevent plants from starting
swiftly and seizing spikes in real-time
market prices.
Minnesota Municipal Power Agency's
(MMPA's) Faribault Energy Park-a 285MW
natural gas-fired combined cycle
plant operated by NAES Corp.-is one facility
that struggled with just that problem.
Its GE A10 steam turbine, rated at
117 MW, consists of a high-pressure (HP)
turbine separated from combined intermediate-
and low-pressure (IP/LP) rotor sections
with both turbine inlets operated at
1,050F.
Originally, when the plant started
up after more than 24 hours offline,
it required some steam turbine warming
time. If it had been offline for 48
hours or more, the plant would enter
a cold-startup phase requiring even
more warming, which severely limited
the plant's ability to adjust to market
changes, start quickly, and capture price
increases.
The plant's turbine rotor, which measures
roughly 30 feet long, expands by
1.25 inches in length as it reaches operating
temperature. The turbine shell
that houses it measures 3 inches to 4
inches thick in places and takes longer
to warm and expand than the rotor.
If the rotor and shell don't warm and
expand at a uniform rate, it can cause
rubbing or binding between rotating
and stationary components. If steam
temperatures are too high or steam is
admitted to the turbine casing too fast,
the unit will automatically trip to prevent
component damage.
With those limitations in mind, plant
management began searching for a way
to improve the unit's operation. The goal
was to minimize steam turbine warming
time while keeping rotor stresses within
allowable limits. The team wanted to reduce
both startup costs and long-term
maintenance expenses.
14
www.powermag.com
POWER | March 2016
1. Warming blankets are not a cold-weather thing. What limits any combined
cycle plant's flexibility is how fast the steam turbine, shown here, can be warmed. Electric heating
blankets can help that process. Courtesy: NAES Corp.
2. Not your typical electric blanket. Blankets are custom-tailored with evenly distributed
heating lines to ensure uniform heating of turbine sections. Courtesy: NAES Corp.

http://www.powermag.com

POWER March 2016

Table of Contents for the Digital Edition of POWER March 2016

Contents
POWER March 2016 - Cover1
POWER March 2016 - Cover2
POWER March 2016 - Contents
POWER March 2016 - 2
POWER March 2016 - 3
POWER March 2016 - 4
POWER March 2016 - 5
POWER March 2016 - 6
POWER March 2016 - 7
POWER March 2016 - 8
POWER March 2016 - 9
POWER March 2016 - 10
POWER March 2016 - 11
POWER March 2016 - 12
POWER March 2016 - 13
POWER March 2016 - 14
POWER March 2016 - 15
POWER March 2016 - 16
POWER March 2016 - 17
POWER March 2016 - 18
POWER March 2016 - 19
POWER March 2016 - 20
POWER March 2016 - 21
POWER March 2016 - 22
POWER March 2016 - 23
POWER March 2016 - 24
POWER March 2016 - 25
POWER March 2016 - 26
POWER March 2016 - 27
POWER March 2016 - 28
POWER March 2016 - 29
POWER March 2016 - 30
POWER March 2016 - 31
POWER March 2016 - 32
POWER March 2016 - 33
POWER March 2016 - 34
POWER March 2016 - 35
POWER March 2016 - 36
POWER March 2016 - 37
POWER March 2016 - 38
POWER March 2016 - 39
POWER March 2016 - 40
POWER March 2016 - 41
POWER March 2016 - 42
POWER March 2016 - 43
POWER March 2016 - 44
POWER March 2016 - 45
POWER March 2016 - 46
POWER March 2016 - 47
POWER March 2016 - 48
POWER March 2016 - 49
POWER March 2016 - 50
POWER March 2016 - 51
POWER March 2016 - 52
POWER March 2016 - 53
POWER March 2016 - 54
POWER March 2016 - 55
POWER March 2016 - 56
POWER March 2016 - Cover3
POWER March 2016 - Cover4
https://www.nxtbook.com/accessintelligence/POWER/pwr_may-2024
https://www.nxtbook.com/accessintelligence/POWER/pwr_april-2024
https://www.nxtbook.com/accessintelligence/POWER/pwr_march-2024
https://www.nxtbook.com/accessintelligence/POWER/pwr_february-2024
https://www.nxtbook.com/accessintelligence/POWER/pwr_january-2024
https://www.nxtbook.com/accessintelligence/POWER/pwr_december-2023
https://www.nxtbook.com/accessintelligence/POWER/pwr_november-2023
https://www.nxtbook.com/accessintelligence/POWER/power-october-2023
https://www.nxtbook.com/accessintelligence/POWER/re-tech-supp-to-power-september-2023
https://www.nxtbook.com/accessintelligence/POWER/power-september-2023
https://www.nxtbook.com/accessintelligence/POWER/power-and-re-tech-supp-september-2023
https://www.nxtbook.com/accessintelligence/POWER/power-august-2023
https://www.nxtbook.com/accessintelligence/POWER/power-july-2023
https://www.nxtbook.com/accessintelligence/POWER/power-june-2023
https://www.nxtbook.com/accessintelligence/POWER/power-may-2023
https://www.nxtbook.com/accessintelligence/POWER/power-april-2023
https://www.nxtbook.com/accessintelligence/POWER/power-march-2023
https://www.nxtbook.com/accessintelligence/POWER/power-february-2023
https://www.nxtbook.com/accessintelligence/POWER/power-january-2023
https://www.nxtbook.com/accessintelligence/POWER/power-december-2022
https://www.nxtbook.com/accessintelligence/POWER/power-november-2022
https://www.nxtbook.com/accessintelligence/POWER/Power-October-2022-140th-Anniversary-Supp
https://www.nxtbook.com/accessintelligence/POWER/Power-October-2022-and-Anniversary-Supp
https://www.nxtbook.com/accessintelligence/POWER/power-and-re-tech-supp-september-2022
https://www.nxtbook.com/accessintelligence/POWER/power-september-2022
https://www.nxtbook.com/accessintelligence/POWER/power-august-2022
https://www.nxtbook.com/accessintelligence/POWER/Power-July-2022-Intl
https://www.nxtbook.com/accessintelligence/POWER/power-july-2022
https://www.nxtbook.com/accessintelligence/POWER/power-june-2022-intl
https://www.nxtbook.com/accessintelligence/POWER/power-june-2022
https://www.nxtbook.com/accessintelligence/POWER/power-may-2022
https://www.nxtbook.com/accessintelligence/POWER/power-may-2022-intl
https://www.nxtbook.com/accessintelligence/POWER/power-april-2022
https://www.nxtbook.com/accessintelligence/POWER/Power-April-2022-Intl
https://www.nxtbook.com/accessintelligence/POWER/power-march-2022
https://www.nxtbook.com/accessintelligence/POWER/power-february-2022
https://www.nxtbook.com/accessintelligence/POWER/power-january-2022
https://www.nxtbook.com/accessintelligence/POWER/power-december-2021
https://www.nxtbook.com/accessintelligence/POWER/power-top-plants-supp-december-2021
https://www.nxtbook.com/accessintelligence/POWER/power-november-2021
https://www.nxtbook.com/accessintelligence/POWER/power-october-2021
https://www.nxtbook.com/accessintelligence/POWER/power-september-2021
https://www.nxtbook.com/accessintelligence/POWER/power-august-2021
https://www.nxtbook.com/accessintelligence/POWER/power-july-2021
https://www.nxtbook.com/accessintelligence/POWER/power-june-2021
https://www.nxtbook.com/accessintelligence/POWER/power-may-2021
https://www.nxtbook.com/accessintelligence/POWER/power-april-2021
https://www.nxtbook.com/accessintelligence/POWER/power-march-2021
https://www.nxtbook.com/accessintelligence/POWER/power-february-2021
https://www.nxtbook.com/accessintelligence/POWER/power-january-2021
https://www.nxtbook.com/accessintelligence/POWER/power-december-2020
https://www.nxtbook.com/accessintelligence/POWER/power-november-2020
https://www.nxtbook.com/accessintelligence/POWER/power-october-2020
https://www.nxtbook.com/accessintelligence/POWER/power-september-2020
https://www.nxtbook.com/accessintelligence/POWER/power-august-2020
https://www.nxtbook.com/accessintelligence/POWER/power-july-2020
https://www.nxtbook.com/accessintelligence/POWER/power-june-2020
https://www.nxtbook.com/accessintelligence/POWER/power-may-2020
https://www.nxtbook.com/accessintelligence/POWER/power-april-2020
https://www.nxtbook.com/accessintelligence/POWER/power-march-2020
https://www.nxtbook.com/accessintelligence/POWER/power-february-2020
https://www.nxtbook.com/accessintelligence/POWER/power-january-2020
https://www.nxtbook.com/accessintelligence/POWER/power-december-2019
https://www.nxtbook.com/accessintelligence/POWER/power-november-2019
https://www.nxtbook.com/accessintelligence/POWER/power-october-2019
https://www.nxtbook.com/accessintelligence/POWER/power-september-2019
https://www.nxtbook.com/accessintelligence/POWER/power-august-2019
https://www.nxtbook.com/accessintelligence/POWER/power-july-2019
https://www.nxtbook.com/accessintelligence/POWER/power-june-2019
https://www.nxtbook.com/accessintelligence/POWER/power-may-2019
https://www.nxtbook.com/accessintelligence/POWER/power-april-2019
https://www.nxtbook.com/accessintelligence/POWER/power-march-2019
https://www.nxtbook.com/accessintelligence/POWER/power-february-2019
https://www.nxtbook.com/accessintelligence/POWER/power-january-2019
https://www.nxtbook.com/accessintelligence/POWER/power-december-2018
https://www.nxtbook.com/accessintelligence/POWER/power-november-2018
https://www.nxtbook.com/accessintelligence/POWER/power-october-2018
https://www.nxtbook.com/accessintelligence/POWER/power-september-2018
https://www.nxtbook.com/accessintelligence/POWER/power-august-2018
https://www.nxtbook.com/accessintelligence/POWER/power-july-2018
https://www.nxtbook.com/accessintelligence/POWER/power-june-2018
https://www.nxtbook.com/accessintelligence/POWER/power-may-2018
https://www.nxtbook.com/accessintelligence/POWER/power-april-2018
https://www.nxtbook.com/accessintelligence/POWER/power-march-2018
https://www.nxtbook.com/accessintelligence/POWER/power-february-2018
https://www.nxtbook.com/accessintelligence/POWER/power-january-2018
https://www.nxtbook.com/accessintelligence/POWER/power-december-2017
https://www.nxtbook.com/accessintelligence/POWER/power-november-2017
https://www.nxtbook.com/accessintelligence/POWER/power-october-2017
https://www.nxtbook.com/accessintelligence/POWER/power-september-2017
https://www.nxtbook.com/accessintelligence/POWER/power-august-2017
https://www.nxtbook.com/accessintelligence/POWER/power-july-2017
https://www.nxtbook.com/accessintelligence/POWER/power-june-2017
https://www.nxtbook.com/accessintelligence/POWER/power-may-2017
https://www.nxtbook.com/accessintelligence/POWER/power-april-2017
https://www.nxtbook.com/accessintelligence/POWER/power-march-2017
https://www.nxtbook.com/accessintelligence/POWER/power-february-2017
https://www.nxtbook.com/accessintelligence/POWER/power-january-2017
https://www.nxtbook.com/accessintelligence/POWER/power-december-2016
https://www.nxtbook.com/accessintelligence/POWER/power-november-2016
https://www.nxtbook.com/accessintelligence/POWER/power-october-2016
https://www.nxtbook.com/accessintelligence/POWER/power-september-2016
https://www.nxtbook.com/accessintelligence/POWER/power-august-2016
https://www.nxtbook.com/accessintelligence/POWER/power-july-2016
https://www.nxtbook.com/accessintelligence/POWER/power-june-2016
https://www.nxtbook.com/accessintelligence/POWER/power-may-2016
https://www.nxtbook.com/accessintelligence/POWER/power-april-2016
https://www.nxtbook.com/accessintelligence/POWER/power-march-2016
https://www.nxtbook.com/accessintelligence/POWER/power-february-2016
https://www.nxtbook.com/accessintelligence/POWER/power-january-2016
https://www.nxtbook.com/accessintelligence/POWER/power-december-2015
https://www.nxtbook.com/accessintelligence/POWER/power-november-2015
https://www.nxtbook.com/accessintelligence/POWER/power-october-2015
https://www.nxtbook.com/accessintelligence/POWER/power-september-2015
https://www.nxtbook.com/accessintelligence/POWER/power-august-2015
https://www.nxtbook.com/accessintelligence/POWER/power-july-2015
https://www.nxtbook.com/accessintelligence/POWER/power-june-2015
https://www.nxtbook.com/accessintelligence/POWER/power-may-2015
https://www.nxtbook.com/accessintelligence/POWER/power-april-2015
https://www.nxtbook.com/accessintelligence/POWER/power-march-2015
https://www.nxtbook.com/accessintelligence/POWER/power-february-2015
https://www.nxtbook.com/accessintelligence/POWER/power-january-2015
https://www.nxtbook.com/accessintelligence/POWER/power-december-2014
https://www.nxtbook.com/accessintelligence/POWER/power-november-2014
https://www.nxtbook.com/accessintelligence/POWER/power-october-2014
https://www.nxtbook.com/accessintelligence/POWER/power-september-2014
https://www.nxtbook.com/accessintelligence/POWER/power-august-2014
https://www.nxtbook.com/accessintelligence/POWER/power-july-2014
https://www.nxtbook.com/accessintelligence/POWER/power-june-2014
https://www.nxtbook.com/accessintelligence/POWER/power-may-2014
https://www.nxtbook.com/accessintelligence/POWER/power-april-2014
https://www.nxtbook.com/accessintelligence/POWER/power-march-2014
https://www.nxtbook.com/accessintelligence/POWER/power-february-2014
https://www.nxtbook.com/accessintelligence/POWER/power-january-2014
https://www.nxtbook.com/accessintelligence/POWER/power-december-2013
https://www.nxtbook.com/accessintelligence/POWER/power-november-2013
https://www.nxtbook.com/accessintelligence/POWER/power-october-2013
https://www.nxtbook.com/accessintelligence/POWER/power-september-2013
https://www.nxtbook.com/accessintelligence/POWER/power-august-2013
https://www.nxtbook.com/accessintelligence/POWER/power-july-2013
https://www.nxtbook.com/accessintelligence/POWER/power-june-2013
https://www.nxtbook.com/accessintelligence/POWER/power-may-2013
https://www.nxtbook.com/accessintelligence/POWER/power-april-2013
https://www.nxtbook.com/accessintelligence/POWER/power-march-2013
https://www.nxtbook.com/accessintelligence/POWER/power-february-2013
https://www.nxtbook.com/accessintelligence/POWER/power-january-2013
https://www.nxtbook.com/accessintelligence/POWER/power-december-2012
https://www.nxtbook.com/accessintelligence/POWER/power-november-2012
https://www.nxtbook.com/accessintelligence/POWER/power-october-2012
https://www.nxtbook.com/accessintelligence/POWER/power-september-2012
https://www.nxtbook.com/accessintelligence/POWER/power-august-2012
https://www.nxtbook.com/accessintelligence/POWER/power-july-2012
https://www.nxtbook.com/accessintelligence/POWER/power-june-2012
https://www.nxtbook.com/accessintelligence/POWER/power-may-2012
https://www.nxtbook.com/accessintelligence/POWER/power-april-2012
https://www.nxtbook.com/accessintelligence/POWER/power-march-2012
https://www.nxtbook.com/accessintelligence/POWER/power-february-2012
https://www.nxtbook.com/accessintelligence/POWER/power-january-2012
https://www.nxtbook.com/accessintelligence/POWER/power-november-2011
https://www.nxtbook.com/accessintelligence/POWER/power-october-2011
https://www.nxtbook.com/accessintelligence/POWER/power-september-2011
https://www.nxtbook.com/accessintelligence/POWER/power-august-2011
https://www.nxtbook.com/accessintelligence/POWER/power-july-2011
https://www.nxtbook.com/accessintelligence/POWER/power-june-2011
https://www.nxtbook.com/accessintelligence/POWER/power-may-2011
https://www.nxtbook.com/accessintelligence/POWER/power-april-2011
https://www.nxtbook.com/accessintelligence/POWER/power-march-2011
https://www.nxtbook.com/accessintelligence/POWER/power-february-2011
https://www.nxtbook.com/accessintelligence/POWER/power-january-2011
https://www.nxtbook.com/accessintelligence/POWER/power-december-2010
https://www.nxtbook.com/accessintelligence/POWER/power-november-2010
https://www.nxtbook.com/accessintelligence/POWER/power-october-2010
https://www.nxtbook.com/accessintelligence/POWER/power-september-2010
https://www.nxtbook.com/accessintelligence/POWER/power-august-2010
https://www.nxtbook.com/accessintelligence/POWER/power-july-2010
https://www.nxtbook.com/accessintelligence/POWER/power-june-2010
https://www.nxtbook.com/accessintelligence/POWER/power-may-2010
https://www.nxtbookmedia.com