It costs British industry an estimated £lbn a year to control
and remove the lime scale that furs up pipes and heating elements,
increasing pumping costs and reducing energy efficiency. Now to
the surprise of sceptics, researchers at Cranfleld University’s
School of Water Sciences say that magnets clamped around
a water pipe can, under the right conditions, cut
scale formation by up to 50 per cent. The scepticism is
understandable: magic magnets have been credited with a range of
benefits including increases in the milk yield of cows and growing
bigger watermelons.
Simon Parsons, who heads the Cranfield research programme, says:
“I was sceptical before I started. What we have found is that
by applying a strong magnetic field at right angles to the flow
under specific conditions of acidity. temperature and water quality,
you can affect the properties of the solution. “If you get
the conditions right, scale deposition is reduced by 50 per cent
and the scale produced is powdery. It can almost be brushed off.”
His team is exploring how varying water conditions affect the process.
The test rigs used in the research are simple heat exchanger systems.
If scale formation in real heat exchangers could be reduced by 50
per cent, the savings could be very large, he says,
The Cranfield work — financed by an Engineering and Physical
Sciences Research Council grant — is likely to interest organisations
using steam for process heat or operating large-scale space heating
systems.
The oil industry is already interested. Oil wells face significant
scaling problems from the highly mineralised waters extracted along
with the oil. Chemical treatment costs are high, as much as £500,000
a year for a typical North Sea platform, and some magnetic devices
are being tested. We know such devices work,” says Alan Hunton,
an oil industry consultant. “The reason why the technology
is not more widely used is that we have not yet found a really good
explanation of how it works.”
A seminar at Cranfield attracted academic researchers worldwide
to discuss the process.
One theory is that the devices change the surface charge on dissolved
ions, affecting the way in which they crystallise. With magnetic
treatment more particles remain in suspension and those that settle
on heated surfaces have a chalk-like consistency.
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