Plant & Works Engineering
Keep your heat transfer system under control
Published:  04 February, 2016

What do a golf ball, a hamburger and a bucket of paint have in common? Not much at first sight. But delve deeper into how they’re made and you might find your answer. Thermal fluid systems are commonly used in manufacturing food and beverage, pharmaceutical, textile and plastic products of all kinds, including golf balls, hamburgers and paint. Clive Jones, managing director of thermal fluid specialist Global Heat Transfer, explains how boiler maintenance can make or break a thermal fluid system and ultimately, a manufacturing line.

A typical thermal fluid system is comprised of three main components: a thermal fluid heater or boiler, thermal fluid circulating pumps and an expansion tank. Several adjacent elements also come into the mix, including piping, thermal fluid used within the system and last, but by no means least, the user.

Today’s robust industrial boilers and their burners are the result of more than 150 years of industrial development. Unfortunately, the durability of a boiler can easily become its worst enemy, if it means that the system owner overlooks accurate maintenance.

A thermal fluid heater can last for several decades without needing significant repairs, but only if maintenance and thermal fluid testing is performed regularly. However, because, most of the time, a boiler operates silently somewhere in the background of a manufacturing facility, it is often overlooked by process engineers and facilities managers.

Peace of mind

Legislation makes employers responsible for ensuring all work equipment exposed to conditions causing deterioration that could result in dangerous conditions is inspected regularly. The rule applies to industrial boilers and other combustion equipment like incinerators, ovens and air heaters, which should be the subject of statutory insurance inspections and regular Non-Destructive Tests (NDT).

Apart from the legal implications of not servicing combustion equipment, there are other reasons why you should take proactive boiler and burner maintenance very seriously. Carbon monoxide and dioxide build-ups can be dangerous because they could result in costly downtime and even health and safety issues.

Similarly, boilers or heaters used within thermal fluid systems require regular maintenance to cope with carbon residue, also known as ‘coke’. Left untreated, high amounts of carbon can lead to system blockages, reduced efficiency, high operational costs and even health and safety issues.

For all these reasons, boiler and burner servicing is essential for any manufacturing plant – especially ones that use thermal fluid - to give management and staff the peace of mind that the system is operating at optimum efficiency and the working environment is safe.

Telltale signs

To make sure boilers and burners are working as they should, we recommend performing the appropriate tests, including complete thermal fluid tests, at least once a year, but ideally once every six months.

Often, thermal fluid systems with carbon build-up or boiler issues could continue to function – less and less efficiently - over a long period before they break down. This situation is costly in the end and could result in significant expense, when the system finally breaks down.

To avoid such expenses, you should pay constant attention to the thermal fluid system and periodic boiler tests performed. Annual checks are sometimes part of a company’s insurance requirements, but there are many telltale signs of a faulty boiler or burner maintenance engineers should keep an eye out for.

For example, if the boiler keeps getting intermittent lockouts or faults, there might be a number of potential problems. It could be an electrical fault with the wiring or a chemical fault, but the reason could also be a problem with the burner.

Burners often fail because of faulty gas valves or other consumable parts that wear down and break because of their volatile ‘lifestyle’, where they get very hot and then cool down repeatedly. These parts will require servicing or replacement most often. Another part inside the burner that can cause stoppages is the flame monitoring device or probe. If the probe doesn’t detect the flame, it shuts down the burner straight away.

The variety and complexity of reasons why a boiler or a burner breaks down is impressive and way beyond the reach of this article. Often the problem doesn’t even lie with the heater. A boiler could easily stop working because of temperature problems in the system, which could be caused by faulty exchanges, blockages or even transfer fluid pumps that are spilling oil.

Expert advice

It is a complex system and unless you have a dedicated team in-house, it’s probably safer to call an expert who can perform the relevant tests and necessary servicing in a professional and safe way that also minimises your costs.

The problem is that as long as boilers work, not all companies actually perform proactive maintenance and testing as often as they should, despite the service being included in many thermal fluid maintenance plans.

The only solution to this problem is regular maintenance, which means daily temperature checks of the thermal fluid and recording any unusual temperatures in a log, so that when an engineer comes in for a full inspection, they have all the information they need to identify any trends or risks in the system.

The only way of checking the health of a boiler and heat transfer system is to test the oil. Hot oil samples, which should be taken every three months, would show if there were any issues that needed to be addressed through partial dilutions, a system flush or other methods.

Next generation

Upgrading an existing heat transfer system can also reduce costs further and better monitor activity. Electronically controlled direct drives, proportional-integral-derivative temperature controllers or proportional valves can very quickly improve a system’s functionality and reduce operational costs.

If you are feeling particularly brave, you might also want to consider commissioning a new boiler, especially if yours is more than 15 years old. If you combine a new energy-efficient boiler with the latest burner and control technology, you will definitely see a marked reduction in fuel bills.

Not all manufacturers will be in a position to change the boilers and burners used on production lines, but every manufacturer should make an effort to ensure they check existing combustion equipment regularly and heat transfer fluid every three months. Regardless of what your company makes, whether it’s golf balls, the almightily hamburger, paint or something completely different, you need to make sure the silent blazing giant that is your industrial boiler is healthy and isn’t the cause of any unwelcomed downtime.

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