Keeping the Power On
18 September 2007 14:30
ELGA Process Water assists Shoreham Power Station when raw water quality changes
High purity water is critical to a wide range of industries, but nowhere more so than in power generation, where loss of high purity water can shut down generation in a matter of hours. Plant for producing high purity water uses well proven unit processes that are selected and designed to handle a particular quality of 'raw' water. But what happens when the raw water quality changes? ELGA Process Water has the answer.
Scottish Power's Shoreham 400MW CCGT Power Station in Brighton is an in-line, single-shaft combination of gas turbine generator and steam turbine with a seawater direct cooling system using the cooling water pumphouse and outfall structures of the old Brighton B station. It consumes 15m³/h of high purity boiler make-up water supplied from a two stream ion exchange demineralisation plant using counter flow, packed bed regeneration technology and delivering make-up water with conductivity less than 0.1µS/cm.
The raw water that supplies the demineralisation plant is drawn from boreholes close to the coast, and normally has a conductivity of around 500µS/cm. The succession of dry winters, which is currently causing water supply problems across the south of England, has resulted in a fall in the water table in the area around Brighton. This has allowed sea water to intrude into the boreholes causing problems for Station Chemist, Keith Carter.
"It's more than just a sea water intrusion problem," explains Carter, "We installed an on-line sodium monitor and this showed a wide variation in concentration that was quite clearly linked to tides." The demineralisation plant was designed to produce 120m³ of treated water between regenerations, but the deteriorating water quality reduced this to less than 40m³ and also caused an increase in treated water conductivity.
"The increase in sodium concentration ultimately led to a complete failure of the demineralisation plant." Keith continues, "We decided to install a reverse osmosis plant upstream, but the project was going to take several months and we had an immediate problem."
The answer to that immediate problem was provided by ELGA process Water in the form of an AQUAMOVE mobile water treatment system. The temporary plant consisted of an AQUAMOVE MORO mobile reverse osmosis unit and an AQUAMOVE MODI ion exchange system. The MODI units are standard 40 foot trailers which are insulated and supplied with heating, lighting and all necessary safety equipment and just need to be connected to the water supply. The MORO units are 20 foot containers similarly fitted out.
"We initially rented the MODI trailer to get over the short term problem," says Keith, "and then continued to rent the MORO reverse osmosis container to provide pre-treatment until our new reverse osmosis system was installed and commissioned."
With water resources coming under increasing stress, changes in raw water quality, like that experienced by Scottish Power at Shoreham, are becoming increasingly common, ELGA Process Water's AQUAMOVE fleet are there to help and can usually be on the road within two hours of a customer’s call to the emergency helpline 01782 590800 - any time, day or night, 365 days per year.
For more information on this company:
ELGA Process Water - Industrial Water Treatment
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