Hevasure Case Study Zwolle District Heating Scheme€¦ · Hevasure Case Study Zwolle District...
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The Biomass District Heating Facility in Zwolle District heating schemes, especially when powered by renewable energy such as bio- mass, are becoming increasingly common in the UK and mainland Europe. Not only do they use renewable energy but, because they use a centralised boiler, they produce heang in a more efficient way than the alternave approach of having a boiler located in each apartment. Where they are similar to ‘convenonal’ heang is that they incorporate a closed heang sys- tem (LTHW) that transports heated water to radiators in each room. However, this system is prone to corrosion damage if not properly monitored and with such a large system, the direct and indirect costs of such damage can be extremely high and any consequenal disrupon to the heang supply completely unacceptable. Hevasure * were approached in the summer of 2013 by Spirotech in the Netherlands to moni- tor a district heang scheme in Zwolle. This scheme supplies hot water to around 400 apart- ments (see photograph below) and was installed and maintained by Cogas. We visited the site in October 2013 and installed our monitoring equipment in the main plant room and at the highest point in the heang system. * formally part of Midland Corrosion Services Ltd Hevasure Case Study Zwolle District Heating Scheme The Hevasure Premier service provided 24x7 monitoring with alerts being issued if parame- ters exceeded crical levels. We also pro- duced a monthly report showing how parame- ters changed over me and made recommenda- ons to keep the system operang in peak health, efficiently and free from corrosion damage.
Transcript of Hevasure Case Study Zwolle District Heating Scheme€¦ · Hevasure Case Study Zwolle District...
The Biomass District Heating Facility in Zwolle
District heating schemes, especially when powered by renewable energy such as bio-
mass, are becoming increasingly common in the UK and mainland Europe. Not only do they
use renewable energy but, because they use a centralised boiler, they produce heating in a
more efficient way than the alternative approach of having a boiler located in each apartment.
Where they are similar to ‘conventional’ heating is that they incorporate a closed heating sys-
tem (LTHW) that transports heated water to radiators in each room. However, this system is
prone to corrosion damage if not properly monitored and with such a large system, the direct
and indirect costs of such damage can be extremely high and any consequential disruption to
the heating supply completely unacceptable.
Hevasure* were approached in the summer of 2013 by Spirotech in the Netherlands to moni-
tor a district heating scheme in Zwolle. This scheme supplies hot water to around 400 apart-
ments (see photograph below) and was installed and maintained by Cogas. We visited the site
in October 2013 and installed our monitoring equipment in the main plant room and at the
highest point in the heating system. * formally part of Midland Corrosion Services Ltd
Hevasure Case Study
Zwolle District Heating Scheme
The Hevasure Premier service provided 24x7 monitoring with alerts being issued if parame-ters exceeded critical levels. We also pro-duced a monthly report showing how parame-ters changed over time and made recommenda-tions to keep the system operating in peak health, efficiently and free from corrosion damage.
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Co
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Data for District Heating Scheme, Zwolle - November 2013
Conductivity (uS)
Temperature ( degC)
DO (PPM)
pH (pH)
Galvanic Current (mA)
Crevice Corrosion inner (ohms)
Graphical view of data for November 2013
Recent dashboard view of data
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Contact Us
For more information about the Hevasure Monitoring Service, please contact
Hevasure Ltd Tel, 01629 735 743
Stancliffe House Email: [email protected]
Darley Dale Web : www.hevasure.com
Derbyshire DE4 2HJ
System Integrity
Dissolved oxygen It is essential that DO is low in a closed system (ideally less than 0.2 mg/
L). Dissolved oxygen is the main driver of corrosion as without this there is
no cathodic reaction. By measuring DO we can ensure the system is air-tight
and that any oxygen introduced by fresh aerated water is quickly consumed.
Pressure A closed system must maintain a positive relative pressure at all times to avoid air being sucked into the system. We monitor this at the highest point in the building using a small satellite monitoring system.
Temperature This is measured to ensure the system is operating as intended.
Water make-up We measure water make-up volume to indicate leaks in the system or inform
us on planned flushing activities
Water Characteristics
Conductivity For inhibited systems, measuring conductivity tells us the concentration of the water treatment products (inhibitors). We will be able to tell if a system is be-ing overdosed or under-dosed with inhibitor.
pH For systems containing aluminium we check that the pH is not going above 8.5 (otherwise the passive films break down and aluminium components such as heat exchangers can start to corrode)
Biofilm risk When biofilms form microbial influenced corrosion often occurs and this can lead to wall thinning and pin-holing in metal pipes. We are trialling a sensor that will hopefully enable us to monitor the risk of biofilm formation
Corrosion
Galvanic currents We have developed our own sensor to monitor the currents that occur be-tween different metals in the system leading to serious corrosion. In plain wa-ter galvanic currents increase in proportion to dissolved oxygen. However, inhibitors when at the correct strength passivate metal surfaces and suppress galvanic currents. By using this sensor we can check that the inhibitor is do-ing its job effectively, even when there is some oxygen in the system.
Crevice corrosion This is a very insidious form of corrosion leading to rapid pitting attack and pin-holing. It occurs in localised regions such as weld seams and under debris due to a micro-environment being set-up. We have developed and patented our own sensor to detect this.
Parameters Monitored
