Cooling Tower Breakthrough

WATER engineering experts have spared one of Europe’s most important chemical plants from an expensive overhaul – thanks to an underwater cleaning robot.

Panton McLeod normally offers specialised services to the drinking water industry, where its robot cleans water tanks without customers seeing taps run dry. Now it has carried out a its first ever industrial project, a successful clean at the INEOS ChlorVinyls site in Runcorn, Cheshire with no down time.

The multi-award winning plant is one of the biggest chlor-alkali producers in Europe. As well as producing chlorine and caustic soda, its chemicals are used in water treatment, paper making, the food industry and making soaps and detergents.

Production depends on cooling water systems working effectively during chemical processes and the plant has a series of water cooling towers. The water recirculation system within the towers has to be cleaned regularly, to ensure efficiency and to satisfy Health and Safety standards.

Plant managers normally plan months in advance to bypass the cooling towers at huge expense in terms of materials, equipment and manpower. Now Panton McLeod has carried out a full clean while the system remained up and running, using the underwater cleaning robot, a mini sub and a custom-made telescopic suction device.

Iain Weir, managing director of Panton McLeod, said: “It has been extremely challenging project and there were a few unforeseen obstacles along the way, but INEOS ChlorVinyls’ people are delighted with the final results, as are we.

“The plant is a huge concern and runs 24 hours a day, 365 days a year and the possibility of being able to put equipment into these towers and clean them to the highest standard without having to shut down production is the dream option.”

Water cooling towers suck in air which is blown across droplets of heated water. As the heat transfers to the air, it is blown up and out of the top of the tower, while cooled water drops back down into the collection pools and is pumped back through the plant as a coolant.

Air sucked in contains dust particles, as well as bigger debris, like leaves and grit. That settles and forms sludge or is stirred up by turbulence affecting the efficiency of the entire cooling process.

Panton McLeod has spent 15 years in the drinking water sector, cleaning the huge underground tanks, called service reservoirs, which are essential to the public supply. Its VR600 robot allows such tanks to be cleaned without shutting of supplies to customers and still meeting the incredibly stringent purity demands of water regulators.

The INEOS ChlorVinyls cooling tower has 14 separate water compartments and the powerful pumps and constant falling droplets cause major turbulence and dramatically reduced visibility, problems not encountered in drinking water tanks.

So, a mini sub fitted with powerful lights and cameras surveyed all 14 compartments before the clean. To reach difficult areas and remove some of the larger debris, Panton McLeod engineers designed and built a “suction boom” - a telescopic arm with a powerful pump at the end.

They also modified the VR600 by raising its tracks and fitting a more robust discharge hose. Water pumped out was put through settlement and filtration treatment and returned to the cooling tower. The waste was disposed of by licensed experts.

Iain added: “The VR600 coped fantastically with the turbulence and in the suction boom we have designed and developed an entirely new piece of equipment. This job is a perfect case study for our ability to overcome problems. As far the VR600 is concerned, nobody else has used this machine in this way – it is a world first.

“INEOS ChlorVinyls has several other water cooling towers and I suspect there will be any number of other plants who will be interested in having cooling towers or recirculation systems cleaned without any down time. This could be a very important shift in the emphasis of our business.”

Paul Taylor, the INEOS ChlorVinyls Site Utilities Asset Engineer, said the site is made up of 20 separate, but interlinked production plants, served by seven cooling towers. He added: “The cooling tower cleaned by Panton McLeod is one of the main one cooling water to the chlorine production plant. If this was taken out of operation it would have a dramatic impact on our chlorine production.

“We have carried out other ways to clean the tower without shutting down production but this is by a very long way the most impressive and effective. There was absolutely no down time, it required very little manpower from us and it is definitely cleaned to standards to satisfy the HSE.”

Paul said the Panton McLeod method was assessed as low risk and also brought important savings by recycling water that is already in the system. He added: “For our point of view it has been excellent.

“I have already spoken to Panton McLeod about coming in next year to do another tower for us and have no doubt that this will be of huge interest to anyone who has cooling towers that cannot readily be taken out of production without causing major and costly downtime. We are delighted.”

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