How pharma manufacturers can keep heat transfer efficient

Clive Jones, Global Heat Transfer, discusses best practice for keeping heat transfer systems running efficiently in pharmaceutical manufacturing

We really have come a long way since Alexander Fleming famously discovered what he affectionately referred to as 'mould juice', but which we've come to know as penicillin. The current global pharmaceuticals market is estimated to be worth $300 billion a year and is growing rapidly. Pharmaceutical manufacturing is not only big business, but also pivotal in keeping the population healthy.

Pharmaceutical processing requires the use of specialised heat transfer fluids designed to work at optimal operating temperature for prolonged periods of time. However, fluids must also be flexible: manufacturing pharmaceuticals requires broad operating temperatures because chemical reactions take place at high temperatures, whereas the crystallisation process takes place at lower temperatures.

Furthermore, thermal fluid used in pharmaceutical processing should be food grade in case of incidental contact with the product.

Food grade thermal fluids are highly refined mineral or synthetic oils designed specifically to be used in the processing of products for human consumption - food, beverages and pharmaceuticals. They are non-toxic, non-irritating and have no odour to ensure consumer safety in the event of a leak or spillage. As you can imagine, this is an essential health and safety measure in the pharmaceutical industry.

Food grade fluids carry a HT-1 certificate issued by governing bodies such as NSF International and the US Food and Drug Association (FDA).

Maintenance

Heat transfer fluid maintenance and analysis are essential operations that need to be conducted on a regular basis. Unfortunately, some plant managers don’t realise there is a problem until it’s too late.

A heat transfer fluid’s thermodynamic attributes vary according to operating conditions. At high temperatures, a thermal fluid will experience chemical degradation. The freezing point of thermal fluid must be lower than ambient conditions. Alternatively, the temperature of the thermal fluid needs to be kept above ambient temperature to stop the heat transfer fluid from freezing. For example, some products freeze at 12 degrees Celsius, which is higher than you might expect.  

To keep heat transfer systems in tip top shape, regular monitoring needs to be undertaken to establish the condition of the fluid. The best way to get the most out of thermal fluid is to test thoroughly and regularly. Regular representative fluid analysis and top-ups ensure a healthy system, while reducing downtime and decreasing the amount of costly thermal fluid changes.

Problems in heat transfer systems occur when fluids are left for prolonged periods of time without correct supervision and preventative maintenance. Due to their chemical structure, thermal fluids degrade with age. Thermal cracking and oxidation cause molecules in the oil or fluid to break down, which produces solid carbon. If left, this carbon builds up and clogs pipes, making the entire system inefficient and more expensive to heat.

At this stage, maintenance activities are relatively easy to conduct, as the carbon is still soft and can be flushed by using thermal cleaning products.

However, if the fluid is left to degrade further, pharmaceutical manufacturing companies run the risk of solid carbon becoming baked onto the inside of the heat transfer system - causing dangerous hot spots. Carbon is an excellent insulator and if hot spots form near the heating element of a system, there is a severe fire risk. 

Blocked pipes and hot spots eventually lead to breakdowns and costly repairs or replacements, not to mention the added expenses associated with flushing the system and refilling.

In addition, disposal of old fluids has to be carried out by qualified professionals in accordance with environmental regulations. This can be extremely expensive if unplanned, hence the need to have a comprehensive maintenance contract in place.  

Light ends are another aspect of heat transfer fluid degradation that pharmaceutical manufacturers need to be aware of. The formation of short-chained hydrocarbons, or light ends, are denoted by a decrease in flash temperature, which represents a potential fire risk. This is because light ends have lower boiling and ignition temperatures. Flash temperature represents the proportion of flammable decomposition products in a thermal oil.

The development of light ends needs to be monitored by routine laboratory testing of open and closed flash temperatures, because poorly maintained heat transfer systems pose a danger to staff and infrastructure.

By monitoring heat transfer fluids on a regular basis, it is possible to detect problems and to take preventative actions that minimise degradation and oxidation, keeping pharmaceutical heat transfer applications efficient and cost-effective.

Ideally, any plant using heat transfer fluids should create a robust maintenance plan that contains regular system analysis, fluid top-up and careful flashpoint and fouling management.

Maintaining a healthy heat transfer system is key for keeping a pharmaceutical manufacturing line rolling. Plant managers have to contend with severe costs associated with downtime should thermal fluids be left to degrade to an extreme level. Well-maintained and healthy fluids facilitate a harmonious heat transfer system, which in turn keeps producing the medicines for a healthy world.