Energy-saving heat exchangers reduce downtime by months

Breakthrough technology

Hydroniq must be doing something right because this is the third contract it has won with Aas Mekaniske Verksted. So what is the company’s breakthrough?

“The Pleat seawater cooler is a type of plate cooler, but at the same time [it is] different to a traditional plate heat exchanger,” says Hydroniq head of corporate communications Endre Johansen. “Both are installed in the engineroom and the functionality for both products is the same: to cool down the main engine and auxiliary systems through the use of seawater.”

But it is here that the technology differs in terms of principle and design. “One Pleat cooling element is equal to approximately 15 plates in a traditional plate heat exchanger,” Mr Johansen continues. “A Pleat system is dismantled, cleaned under high pressure and the few robust elements are easily reassembled and made watertight. One person can do the job in an hour.”

The Rack system, Hydroniq’s latest model, represents another step or two up in terms of technology. Not only does it save room by being installed in the hull, it is equipped with frequency-controlled pumps that require low back pressure to push the same amount of seawater through the system.

“This reduces energy consumption significantly versus, for example, traditional plate heat exchangers,” says Mr Johansen. “They require higher and higher water pressure to push seawater through the system when the plates are clogged, for instance by marine growth.”

Hydroniq has not by any means turned its back on more traditional heat exchangers. With more than 200 standard models of shell and tube-type products with a wide range of cooling surfaces, it continues to service the traditional market.

But the Rack system is its top-ranked technology. A highly condensed system, it boasts several features: there is one lifting point, reducing handling problems; a protection shield prevents foreign particles from invading the system; hidden away in the hull, generally between the frames in a double-bottomed structure, it is a space saver; with few service gaskets to replace, it is labour-friendly; and because the system is completely insulated from the hull structure, there is no risk of galvanic corrosion.

Among other advantages, the tubes are designed to minimise marine growth and other unwanted invasions that can rapidly clog up heat exchangers. Unlike box-type coolers, it does not need to be dry-docked. And there is a heat recovery element that captures surplus energy for other uses.

Hydroniq claims substantial savings for its latest technologies. Perhaps most importantly, Hydroniq has learned from clients that cleaning time is reduced by as much as 90%.

When towage group PSA Marine retrofitted the Pleat coolers on its fleet of 12 tugboats at work on Singapore Bay, it kept comparative records of the benefits. Until then, crews had spent a total of 2,500 hours a year maintaining the cooling systems for the fleet, a process that required the pipes to be dismantled and the heat exchangers cleaned just about every week.

“But with the Hydroniq Pleat coolers installed, we were able to extend the cleaning program by 10 months for each vessel,” PSA reports. This has significantly reduced resource costs and downtime for the vessel owner.

Overall cleaning time per unit fell from eight hours to one hour. The corporation estimated it got the original US$15,000 investment back in four months.