A familiar problem: It feels like 40 degrees in the shade and you are sweating in the office when suddenly the fan stops working. Luckily, replacing it is not that big of a problem. It is a different matter for the cooling towers used in indus­trial appli­ca­tions. They are often as large as a small apart­ment and not so easy to replace. That is where Aggreko comes into play.

Global rentals

Wher­ever process heat is gener­ated and customers are unable to fall back on equip­ment of their own, Aggreko is not far away. The company, with head­quar­ters in Glasgow, Scot­land, special­izes in renting cooling towers for any dura­tion or schedule, be it short-, medium- or long-term, among other prod­ucts. “We’re there when some­body needs to perform main­te­nance or repairs on a cooling tower, whether it’s in an oil refinery, a steel mill, a power plant, a hospital or a univer­sity,” says Billy Childers, National Manager at Aggreko USA. Aggreko has its cooling towers produced by partner compa­nies in China and the United States. They reach customers by ship, airplane or truck. Aggreko was founded in the Nether­lands in 1962. After the company had been in busi­ness for more than 50 years, it became clear in 2017 that it had to repo­si­tion itself in the rental market for cooling towers.

Billy Childers takes care of Aggreko’s U.S. customers from his office near Okla­homa City. (Photo | Shannon Faulk)

The biggest cooling towers are being put to use in the United States. (Photo | Shannon Faulk)

Specially designed fans work inside the cooling towers. (Photo | Shannon Faulk)

Aggreko can be found in 204 places all over the world. (Photo | Shannon Faulk)

Ready to ship: Built as inter­modal containers, the cooling towers reach customers by ship, truck or plane. (Photo | Shannon Faulk)

Billy Childers checks order papers with an employee. (Photo | Shannon Faulk)

At their Okla­homa City facility, Aggreko's cooling towers are tested before they are rented to customers. (Photo | Shannon Faulk)

Two factors played a major role in this deci­sion: trans­porting the cooling towers, and using them. Aggreko’s fleet consisted of 14 different cooling tower models, which caused prob­lems because they were not designed for container­ized trans­port and took up too much space on-board ships and aircraft. And of course that costs money. “Trans­porting a cooling tower by ship cost us about 25,000 dollars,” says Billy Childers. Frequency vari­a­tions from country to country also posed a chal­lenge to providing a stan­dard­ized solu­tion for trouble-free oper­a­tion world­wide: the U.S. power grid usually oper­ates at 60 Hz, the Euro­pean and Asian grids at 50 Hz.

New focus: keep it simple

Aggreko initi­ated a project called Global Towers, reducing its fleet to two new models, both of which are designed for container trans­port and differ in size and capa­bility: the GT40 and the GT20. The number stands for the container size in feet. A smaller size is planned for the future. “Now trans­porting a cooling tower by ship only costs us about 2,500 dollars,” says Billy Childers.

Billy Childers values the good inter­na­tional coop­er­a­tion with ebm-papst. (Photo | Shannon Faulk)

At the same time, Aggreko switched from AC fans to EC fans, which can be adjusted better to various partial load ranges and also operate more effi­ciently. It also wanted the ability to query perfor­mance data remotely, some­thing only new EC fans could do. Aggreko chose a few poten­tial suppliers, including ebm-papst. “We received a request to produce a proto­type,” recalls Daniel Yiu. As Regional Manager Sales at ebm-papst, he is respon­sible for southern China and Hong Kong and was in close contact with the Chinese cooling tower manu­fac­turer. “This project was very impor­tant for us because Aggreko is such a big customer. We wanted to offer the best possible product.”

Inter­na­tional coop­er­a­tion

After ebm-papst Mulfingen designed and built the proto­types, Yiu arranged for measure­ments of the fan in a cooling tower. An intense period of discus­sions across multiple time zones and coun­tries began. “We were in touch every day,” recalls Yiu, “at first with the cooling tower manu­fac­turer and later directly with Aggreko when it was time to adapt the required spec­i­fi­ca­tions.” Such an Aggreko cooling tower has to deliver high perfor­mance — at ambient temper­a­tures of up to +60° Celsius since many of the towers are used by customers in the Middle East. The same applies for its key compo­nents, the fans. Not only are they subjected to high temper­a­tures, they are also exposed to constant humidity since they work with evap­o­ra­tive cooling. But the biggest chal­lenge for ebm-papst was that the fan had to cope with the high back pres­sure resulting from the compact, container-based design.

An Aggreko cooling tower must be able to achieve great things – at ambient temper­a­tures of up to 60 degrees Celsius. (Photo | Shannon Faulk)

Impressed by the supplier

In the end, Aggreko got a rugged fan with H2+C design; its special coat­ings and paints make it corro­sion-resis­tant, it can handle oper­ating temper­a­tures as high as +80° Celsius, and it resists high back pres­sures. Billy Childers is satis­fied, saying “Our previous AC models needed a lot of main­te­nance in the hot, humid envi­ron­ment where they are used. The failure rate was very high. We’re convinced that that will change with the prod­ucts from ebm-papst.” Childers values the good inter­na­tional coop­er­a­tion. He says, “There were lots of meet­ings and talks, and they weren’t always fun. But ebm-papst was always avail­able — on the phone, in person or in some other way. Not every company can guar­antee that at this global level.”