3P-SOLUTIONS S.A.
Status report
Site: PPC Power Plant Lavrion, Unit 2
Time: 19.01.2009 – 23.01.2009
Purpose: Check of PLC-system, status of main control-loops and related drives, upgrade-
possibility to C3,
Done by: 3P-Solutions S.A. Jürgen Chluba
21/22nd January 2009
In order to get an impression, how the present control-system is working, it was necessary to put the
Oil-, Air- and Boiler-Master-Control in “Automatic”. It was found, that as soon as the Oil-Control was
put in auto, the oil control valve started to swing. It was assumed that the following Contronic 2 cards
could be faulty:
• Integral card CT022,
• Interface card CS012 to the Triac Unit GV015 or GV015 itself.
On January 21, all the damping signals to the actuators for both FD-Fans and the damping of the Oil-
Flow-Control-valve actuator were checked. They were all found o.k.
On January 22, first the CS012 Card was removed, with no positive effect. The old card was used
again. In a second step, the CT022 card was replaced, using the following parameter combination:
Tn = 4,7 s and Xp = 80%. To ensure that the spare card CT022 was in a working condition, it was taken
from the atomizing-steam-temperature-controller. After the change, the Oil-Flow-Control-valve was
stable in automatic-mode.
Nothing else was changed, and the load was increased from 140MW to 290 MW with the Air-Control,
the Oil-Flow-Control and the Boiler-Master on automatic.
All control circuits were found stable in “Automatic” from this point on.
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3P-Solutions S.A. Evaluation Phone: +352 / 26 36 26 73
Zone Industrielle Engineering Telefax: +352 / 26 36 26 74
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3P-SOLUTIONS S.A.
The following was observed:
The Oil-Control was following the command of the boiler-master-control. Even when burners were
switched on, it remained stable. The Air-Flow-Control was behaving the same way.
Figure 1 Oil-Flow and Aux-Steam-Flow during load change
The Furnace-Pressure at 289MW, settled at its adjusted value of 420 mmWS.
O² values were ~0.5 Vol.% on both sides at 289MW. Most of the values settled like they did before.
Figure 2: Furnace Pressure (blue) and O²
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3P-Solutions S.A. Evaluation Phone: +352 / 26 36 26 73
Zone Industrielle Engineering Telefax: +352 / 26 36 26 74
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3P-SOLUTIONS S.A.
As it can be seen in Figure 2, the O²-values on low load are pretty much the same like they were before
the card-change (operation mode: manual). After the card-change (automatic-mode) the O²-figures on
high-load became more unstable, but on the other hand lower. Before, high-load O²-values were over
2% (green line O²-picture bottom right side), now they are at about 1.85%. (The red line shows the
same behavior). It is most likely that with Air-Control in automatic the O²-values are kept lower.
The Boiler-Outlet-Pressure was controlled to a low deviation by the operator. During the load change
from 140MW up to 289MW the Drum-Level increased by more than 45mmWS. It settled after 20
minutes to its set value.
Figure 3: Boiler-Outlet-Pressure (blue) Steam-Flow (red) and on the right side Drum-Level (red)
The SH-Temperature varied from 530°C to 556°during the load rise. This variation of 26°C is too
much and can be improved with a new control.
The RH-Temperature varied from 528°C to 555°during the load rise. This variation of 27°C is too
much and can be improved with a new control.
At Full load the Boiler-Outlet-Pressure remained constant, within less than one bar. The Reduction of
the load from 289MW to 140MW in the afternoon was even smoother then the load rice in the
morning.
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3P-Solutions S.A. Evaluation Phone: +352 / 26 36 26 73
Zone Industrielle Engineering Telefax: +352 / 26 36 26 74
L-6468 Echternach Optimization www.3p-solutions.lu
3P-SOLUTIONS S.A.
So far so good, but still the combustion could be improved, if the Atomizing-Steam-Control would
work properly.
Above points are the main points, which have been found during our visit.
Conclusion
So everyone could be happy, and keep going on, but the situation will not improve over the next year.
What happens if more cards are failing during the next few weeks? The unit may trip or has to be run
partially on manual again. There will be continuous trouble with the repair of the Contronis 2 cards. To
ensure a reliable performance of the unit 2 during the next few years, I would like to recommend a
change of the essential control circuits to the proven more reliable Contronic 3 system.
This could be done in two phases:
Phase 1:
New Contronic 3 cubicle with the pre-wired:
• Boiler-Master-Controller
• Air-Controller
• Oil-Flow-Controller.
Optional, during Phase 1 also a new:
• Oil-Pressure-Controller
• Oil-Temperature-Controller.
For all above mentioned Control circuits I would like to recommend also to up-grade or change the
related control actuators to Contrac actuators. Which of the two options; up-grade or new actuators
depends on the economy. It makes no sense, when the upgrade-costs reach the costs of an new
actuator, especially at the smaller types of actuators.
The Opacity-Control circuit should be removed and replaced by an O²-Control, because a modern O²
measurement for both sides of the boiler is already in place.
It is important to improve also the Oil-Pressure- and Oil-Temperature-Control. With better control for
those loops the emissions will be smaller.
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3P-Solutions S.A. Evaluation Phone: +352 / 26 36 26 73
Zone Industrielle Engineering Telefax: +352 / 26 36 26 74
L-6468 Echternach Optimization www.3p-solutions.lu
3P-SOLUTIONS S.A.
But it is more important, to get the Atomizing-Steam-Control probably working. A short visit to the
atomizing steam control station has shown that the arrangement of the station is causing trouble.
The direct measurement with glycerin to keep the oil measurable should be replaced by a new Delta-
Pressure-Transmitter with remote seals. Also a new I/P converter with a feedback unit could be
attached to the atomizing control valve. That gives the opportunity to control the atomizing-steam
more accurate, dependent to the oil pressure.
One last remark to the atomizing steam reducing station; a modern reducing station would control the
pressure to its set value.
Phase 2
Due to the fact that a new Contronic 3 Cubicle will exists after phase 1, the remaining important
control loops like SH-Temperature-Control, RH-Temperature-Control, Boiler-Feed-Pump-Control
with the Drum-Level-Control and last but not least the HP-Bypass-Pressure/Temperature-Control,
could also be changed to Contronic 3.
Summary
As described in the report we will submit an offer for Phase 1 separately. This provides the possibility
to plan the budget for improvement of the control system, which means more reliable running of Unit
2 for the next few Years.
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3P-Solutions S.A. Evaluation Phone: +352 / 26 36 26 73
Zone Industrielle Engineering Telefax: +352 / 26 36 26 74
L-6468 Echternach Optimization www.3p-solutions.lu