Heat of the moment

Heat exchangers are prime movers in the process industries, managing a multitude of precise temperature-controlled processes.

This means they play a major role in the quality of the products rolling off the end of the production line.

But not all are created equal. Heat exchange requirements can range from the very simple to the highly complex, where viscous fluids, shifting solidification points, or unstable, heat-sensitive fluids may be at play.

If you are having to have the equipment cleaned weekly it could cost an awful lot of money

Stephen Wooler

“You have to look at the whole system to make sure you are offering the right solution,” says Stephen Wooler, senior design engineer at HRS Heat Exchangers.

The company tailors bespoke corrugated tube heat exchangers to environmental sludge, food, and industrial customers.

Wooler says corrugated tubes can be more effective for increasing heat transfer rates, offering better efficiency than normal smooth tube heat exchangers.

Many companies are also looking to use heat exchangers in new ways, says Wooler.

“They are not only looking at the design of the heat exchanger, but how they can be used - as in heat recovery, where they reuse warm water for another purpose such as hand washing,” he says.

“Depending on the size of the site, this could save them hundreds or thousands of pounds per year.”

Other new applications are being driven by government programmes, he says. An example is where food waste once sent to landfill is now dispatched to an anaerobic digestion plant to generate electricity from methane gas.

“Ten years no one would have done it, but that is changing as governments increase landfill taxes for food producers,” he says.

When it comes to adopting brand new heat exchanger technology, design of equipment can be based on individual system requirements.

“If their key concerns are about fouling, we can make sure we have the longest running time possible so things like proteins and sugars don’t burn,” says Wooler.

“If you are having to have the equipment cleaned weekly it could cost an awful lot of money and cause an awful lot of downtime.”

Although energy efficiency is a key requirement for some customers, the overriding concern will always be system reliability, says Johan van der Kamp, chief design engineer at Bronswerk.

“People still want proven equipment with 20 years of operation,” he says. Bronswerk’s key markets are oil, gas, chemical and petrochemicals.

“This means we are very aware of many specific temperature, pressure requirements, and this is where we start when looking at solutions,” he says.

Another key industry requirement is to keep the volume and weight of equipment as low as possible.

“The lower the volume and weight, the smaller you can make ships and platforms,” says van der Kamp.

“We do more than design, manufacture and deliver heat exchange equipment. We will also look around to see if can advise on improvements on that small area of the plant.

“Improving efficiency for industrial plants is another of our aims, so a logical extension of our business is heat transfer. We are also working on developing heat pumps and we expect that market to expand.”

Mixing and agitation technology specialist Chemineer has also been working on technology designed to improve energy efficiency and productivity for customers.

Neil Cathie, Chemineer’s Kenics business development manager says the company’s inline mixing technology has spawned the creation of static mixers in heat exchangers for very challenging process environments.

The company works with both equipment manufacturers and end users in the petrochemical industry involved in processing bulk polymers, resins, adhesives and sealants.

“Our aim is to add static mixer technology to the tubes of heat exchangers to dramatically improve heat transfer efficiencies,” says Cathie.

“We are looking at the most difficult and challenging applications in heat transfer. When you have semi-viscous fluids, they are not only much more difficult to heat or cool, but also degradation is an issue as most of them are biodegradable”.

The key to Chemineer’s Kenics heat exchanger is that it incorporates mixing technology.

“Companies are looking to enhance the technology they have had for the last 30 or 40 years,” says Cathie.

“This is because they want to get more out of their existing plant rather than rebuild it.”

Increasing plant efficiency is becoming more important as western companies struggle to compete with those from emerging markets, he adds.

Global drug research company Covance was recently seeking improved energy efficiency for the steam boilers, pump rooms and purifiers for domestic hot water at its Harrogate research centre.

The company says it looked at a range of heat exchangers and chose a plate heat exchanger package system called ENCOsys from ARI because it provided greater energy savings, required less maintenance and had a smaller footprint than some competitors.

It offers a more modern method of using steam to generate hot water in a controlled way, says ARI, making it much more efficient than the traditional ‘shell and tube’ heat exchangers.

Although it is too soon to quantify how Covance has benefited from ARI systems, the company says that energy bills have fallen, alongside the maintenance costs associated with its previous system.