Sarlin Balance compressed air management system helped reduce the need for spare units
The Salmisaari power plant in Helsinki dominates the scenery, although
the enormous mountains of coal were hidden underground in a new storage
area a couple of years ago.
The energy company for the Finnish capital, Helsingin Energia, has
invested in environmental protection, reducing sulphur emissions by over
70% since 1990. This required, among other things, efficient sulphur
Besides electricity, the power plant produces district heating at 300 MW
and district cooling as a by-product of electricity production. The
environmental impacts of the plant are continuously monitored, and the
reporting requirements are stringent.
The sulphur removal system requires a lot of compressed air when it sprays lime into the flue gases.
The average compressed-air demand is 150 m³/min, nearly 80% of it in
sulphur removal. The rest is instrument and working air for the ash
conveyors, and dust removal by sound.
“The demand is not stable but fluctuates according to production.
Including the stand-by compressors, the total capacity is nearly double,
because we cannot compromise the production of electricity and heat in
case of compressed-air system failure.”
“We also needed to improve the air availability in the plant because of a
renewed environmental licence. If we cannot convey lime into the
sulphur removal process at a sufficient rate, we shall have to run down
The compressed-air system is being renovated and upgraded step by step.
The compressor deliveries set the Sarlin compressed-air experts
brainstorming. What they had seen and heard provoked an idea to
modernise the plant.
“The plant featured several compressed air networks and small machines
with spare units in many places. The pipe lines were connected and the
scattered compressors were brought under a common control and monitoring
system, Sarlin Balance. The resulting compressed-air system is safe and
easy to control.”
As Sarlin recommended, the old auxiliary boiler hall houses the new
compressor station which was connected with the main sulphur removal
compressors via a connecting pipe.
“This allows all the units to compress air for any point of use, which
improves the reliability and reduces the need for spare units.”
The compressed-air plant was modernised with the help of Sarlin Balance.
The entire air system with compressors and valves is connected with
Sarlin Balance control and monitoring system. The control room screen
shows the operation, compressed air production and pressure levels of
all the units at a glance. It also helped to optimise the system.
Compressed air is an expensive utility, especially if a high pressure
level is maintained and many compressors run at partial loads.
“We have been able to drop the pressure level from 9 to approximately 8
bar without risking the sulphur removal process. A reduction of 0.1 bar
at the current consumption rates already means savings of about 7,000
euros annually. Further benefits come from heat recovery from the
air-cooled compressors in the new auxiliary boiler station; the heat is
utilised for pre-heating the steam boiler combustion air.”