It is critical that solar thermal fluids are routinely sampled to assess their condition in order to sustain normal operation. When sampling a fluid, an engineer needs to consider their own safety as well as the safest point to sample from a system.

A heat solar thermal fluid can operate up to 400°C

Typical physicochemical properties for commercially available BDO-based HTFs.

Managing fluids at high temperatures presents a safety hazard as the fluid may come into contact with the engineer whilst the fluid is being sampled. This of course needs to be avoided to safeguard personal health and safeguard employees. Indeed, the point from which the fluid is sampled from the system is also an important consideration. The safety considerations from these two perspectives are detailed in Figure 1 and considered in further detail below.

Personal protective equipment and safe sampling points in solar thermal power plants.

Personal protective equipment (PPE)

PPE is defined as any equipment that offers protection against hazards and are there to protect employee health and safety at work according to the Work Regulations Act 1992. Table 2 outlines the PPE that should be considered when sampling a fluid that is in operation as well as the potential risk and how this can be mitigated.

Table 2. Health and safety considerations when sampling solar thermal fluids.

Indeed, engineers must take appropriate precautions when entering potentially hazardous environments, such as concentrated solar power plants, and must be wearing PPE before taking a sample of the fluid. Health and safety considerations include how to protect the eyes, face, skin, ears, head, lungs, hands and feet.

Safe sampling point

The second aspect that has to be considered is the design of the system. When sampling a fluid it is imperative that a suitable sampling site is available – please see Figure 1. Ideally this needs to be a site that is outside so that vapours can escape to air. Also, any leaks would be easier to isolate in an open area as opposed to a closed and confined space. It is also important to identify a point where the fluid has a low pressure to avoid unnecessary sprays and leaks. This helps to further improve the safety of the sampling technique and safeguard the engineer. Lastly, the sampling site needs be part of the circulation so that the sampled fluid provides a representative sample and therefore a fair assessment of the fluid in the system.

Conclusions

The safe sampling of hot HTFs is a fundamental part of the training of engineers sampling solar HTFs. A commitment to safe sampling practices and training ensures that solar HTFs are sampled in a safe manner. Suitable sampling points need to be designed into the system that are outside and that provide a sampling point where a representative volume of fluid can be taken without the risk of the engineer being sprayed by hot fluid.

Figure 2. Solar thermal fluid sampling device.

Sampling needs to be performed by experienced engineers and the correct sampling techniques and equipment need to be used. Figure 2 shows a picture of a hot fluid sampling device that is routinely used by Global Heat Transfer [3]. This is echoed by Wagner [2] who stated that “Relevant regular maintenance services of the system components are necessary and to be carried out by experienced personnel to ensure trouble-free operation of the plant over a longer period.”

Acknowledgements

The author would like to acknowledge the writing support provided by Red Pharm communications, which is part of the Red Pharm company (please see @RedPharmCo on Twitter).

Research article

1. Wright CI, Picot E. Safe sampling and handling of biphenyl diphenyl oxide heat transfer fluids. International Journal of Materials Chemistry and Physics 2 (1), February 2016; 9-14.
2. Wagner WO. Heat transfer technique with organic media. In: Heat transfer media, second ed. Graefelfing, Germany: Maria-Eich-Straβe; 1997. p. 4–58 [Chapter 2].
3. Wright CI, Picot E. Using routine sampling and chemical analysis of heat transfer fluid, early in a plant build, can help to extend the lifetime of CSP plants: A case study. Renewable Energy Focus 2015: Source: http://www.renewableenergyfocus.com/download/1433.

About Chris Wright
Chris Wright is a research scientist, graduating from the University of Leeds in the UK with a BSc and PhD. His research focuses on the use and maintenance of heat transfer fluids in manufacturing and processing, which includes food, pharmaceutical, specialist chemicals and solar sectors.

The content & opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag

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