Heating and Ventilating

 

Water Treatment: Stopping rust without chemicals

A steel factory in Jordan needed to prevent corrosion of its cooling system to keep it running efficiently. It called in equipment from water conditioning manufacturer Hydropath to do a year-long trial of chemical-free corrosion prevention
Water Treatment: Stopping rust without chemicals
The Jordan Steel Factory outside Amman, Jordan, was concerned about corrosion within the pipework of its cooling system, caused by large quantities of sulphate-reducing bacteria, iron oxides and scaling build up.

These combined factors contributed to an overall reduction in the efficiency of the direct and in-direct cooling system at the factory. Corrosion is a major issue for the steel factory as, once the metal pipe work has begun to corrode, the process rapidly accelerates. The management decided to contact the Corrosion Engineering Division of the Royal Scientific Society, Mechanical Design & Technology Centre.

It was decided to carry out a year-long trial of Hydropath's water-conditioning technology. Units from the AquaKlear and Hydroflow ranges were installed at the factory to eliminate the various problems.

An AquaKlear model was fitted to protect the oil cooling heat exchangers and the indirect cooling tower, and a number of customised Aquaklear and Hydroflow units were installed to protect the furnace, direct cooling towers, pipe lines, sand filters and associated applications within the Jordan Steel factory.

A series of test coupons were installed throughout the system to allow results to be recorded. Seven carbon steel coupons with nuts and bolts (made from the same material as the pipes) were located throughout the system to measure corrosion. And a further seven stainless-steel alloy coupons were affixed with plastic nuts and bolts to measure scale build up. Plastic was used to eliminate any interference from galvanic action.

Hydropath technology is different from other water conditioners as it treats all of the water in the filtration system all of the time. It works by inducing coaxial electromagnetic fields through the fluids passing through the pipe. A wave is generated from the unit which is carried throughout the system.

This charge helps prevent the electro-mechanical process of corrosion taking place. The negatively charged electrons are drawn towards the outer skin of the pipe (known as the skin effect) while the heavier positively charged ions are drawn away from the service. The result is that a state of passivity exists within the water.

Other physical water conditioners are flow-dependent. It is necessary for the water to flow within the unit to transfer energy to the water. The flow has to be slow enough to transfer the energy to the water.

If it is too fast, not enough energy will be transferred to create the effect. If the flow is too slow, it will take too long to reach the area where the water is precipitating, and the effect will decay away after about 3.5 minutes. This is the reason that manufacturer's specify flow rates and maximum flow, necessary for proper operation of such devices. Such flow-rates are unlikely to be achieved in practical applications.

The AquaKlear system also reduces bacteria and eradicates algae. It does so by applying a charge to the bacteria, which gets hydrated with a pure water layer. This layer is absorbed into the bacteria by osmosis. This creates osmotic pressure, which bursts the membrane thus killing the bacteria. But, in difficult conditions, the algae and bacteria will form an indestructible cyst, which is virtually impossible to filter out via normal filtration.

Aquaklear resolves this problem by flocculating these micro particles in order to allow filtration to be achieved. Hydropath products also offer cost savings and environmental benefits compared with chemical alternatives. And are easy to install as they require no cutting of pipework.

Following the installation of the AquaKlear and Hydroflow systems, there was a significant reduction in corrosion at the steel factory. The results indicated a reduction of iron oxide percentages by two thirds in the one year period. This reflected positively on reducing corrosion rates. Scaling percentages also reduced dramatically, thus leading to the direct and indirect factory cooling system operating more efficiently.

Independent tests were conducted by the Royal Scientific Society one year after the installation of Hydropath technology. The results were compared with 12 months earlier. Sulphate reducing bacteria reduced from 10.8 to 7.92 cfu, corrosion rates reduced by more than half, and the scale deposits were considered to be 'very thin'.

With industry beginning to take its environmental responsibilities seriously, Hydropath technology offers industry a radical alternative to chemical water treatment. It can also be used for smaller commercial and domestic applications.
1 August 2007

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