| The challenge was
big: For the gas and steam power station in Bristol, Great Britain,
that went on stream at the end of the year 2000, the waste water
of a near-by sewage plant had to be used as cooling water. Siemens
PLC, the designer of the 750 megawatt Seabank Power Station, engaged
Grundfos Alldos for this complex and extensive task in chemical engineering.
Start of the gigantic project was July 1999 comprising the complete
engineering, delivery, installation and finally commissioning on
schedule. The result was a plant, which is unequalled in its dimension
and safety premises worldwide.
The Grundfos Alldos engineers and technicians had to plan in two dimensions.
Main task: the treatment of the cooling water. Three ClO2 systems
disinfect the extremely polluted water of the sewage plant, which
is conveyed back into the plant after the cooling procedure. Chlorine
dioxide was chosen as disinfection agent, because of it's special
chemical characteristics in organically polluted water.
Construction site number 2: the water-steam cycle of the of the
power station. A manually controlled Trisodium-Phosphate-system
prevents corrosion of the hot-water tank in case of leakages,
by keeping the pH-value stable, which is essentially higher than
the value of cooling water. The Hydrazine and Ammonia dosing systems
are running in full-automatic permanent operation and provide
the correct Oxygen content and the correct conductivity.
Stand-by modules guarantee absolute safety against failures in both
sectors. The consumption control and command of dosing are made
automatically by PLC and process visualisation, indicating all flows
and levels optically. A modem connection is the prerequisite for
quick service intervention.
A look at
Customer's plant:
ClO2 system in 24-hours operation
Technical features:
Water quantity (cooling water and additional water): 16.233 kg/second
Treatment process:
HCl and NaClO2
a) Cooling water and additional water:
Treatment and dosing:
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3 ClO2 systems
including tanks, pumps with a total capacity of 20 kg/Std.
(1x10 kg/h, 2x5 kg/h) |
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2 sulphuric
acid systems, measuring systems for ClO2 , pH, redox, chlorite,
m-value |
b) Water-steam cycle:
Dissolving and dosing station, high-pressure dosing:
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2 trisodium phosphate systems, with 15 pumps;
Pump capacity: 10-20 l/h, up to 200 bar
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2
hydrazine and ammonia systems with 6 pumps each;
Pump capacity: 10-20 l/h, up to 200 bar
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