Electricity + Control November 2017

TEMPERATURE MEASUREMENT

abbreviations

CSP – Concentrated Solar Power EHT – Electrical Heat Tracing OPEX – OPerational EXpenditure

Heat Tracing – Choosing the Right System Giles Maynard, eltherm South Africa

Take Note!

Electrical Heat Tracing (EHT) and steam heat tracing play an impor- tant role in maintaining temperatures. EHT systems are gen- erally easy and quick to install, energy efficient with low maintenance (safe choice for pipe and equipment heating). Steam heat tracing is quite cumbersome and time consuming to in- stall (cannot be used on non-metallic pipes).

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Heat tracing plays a critical role in the temperature maintenance of a myriad of applications.

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T he applications in which heat tracing plays a critical role include pipes, storage tanks and vessels; regulating fluid and gas tempera- ture to ensure optimal flow and stability. It is highly customisable and available in both electrical and steam options. However, to understand the funda- mentals of heat tracing, it is important to know the differences between Electrical Heat Tracing (EHT) and steam heat tracing which both offer energy and cost savings in the respective applications. EHT – the safe choice Throughout its history, EHT has been the safe choice for pipe and equipment heating as it can be regulated to deliver precise outputs. EHT essen- tially uses an electrical heating element that runs the length of a pipe; this heating element is then used to regulate temperature. EHT is recommend- ed for use on both metallic and non-metallic, as well as lined piping and process equipment as it is equipped with controls to keep process tempera- tures within specific limits and conserve energy. EHT systems offer a broad range of temper- ature options. They can be designed for applica- tions with low freeze points right up to very high (800 - 1 000ºC) process maintenance temperatures. EHT can also be installed on short or long pipelines which makes it ideal for large Concentrated Solar Power (CSP) farms and petrochemical plants among many other applications. The common misconcep- tion that EHT cannot be installed in Ex areas is false. Like steam tracing, EHT has seenmajor technological advancements allowing it to be installed anywhere. Steam heat tracing – quick heat up Steam heat tracing is a great solution in plants where steam is a by-product of various manufacturing tech-

niques. Simply put, steam heat tracing systems cir- culate steam around pro- cess pipes to heat them. The steam tracing is usu- ally installed by running the steam lines in direct contact with the piping or vessels to be heated. The entire assembly is then

Each system that requires heat tracing should be evaluated individually.

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insulated to direct the heat into the process fluid. One of the main benefits of steam is that it heats up quickly as the highest rate of heat transfer occurs when the difference between the steam tracing and the piping is the highest.This is particularly beneficial during a plant shutdown. What to consider From this discussion it is clear that both EHT and steam heat tracing play an important role in main- taining temperatures. However, EHT does offer fewer drawbacks and drives down OPerational EX- penditure (OPEX). EHT systems are generally easy and quick to install, use energy efficiently and offer low mainte- nance costs and can be monitored remotely. Many systems today make use of self-regulating cables which optimise the temperature control process. Steam heat tracing is quite cumbersome and time consuming to install and cannot be used on non-metallic pipes. Furthermore, it is far more expensive to maintain as it makes use of fittings which have a propensity to leak. Overall, steam heat tracing has a much higher OPEX. Conclusion Ultimately there is no cookie cutter solution. Each system that requires heat tracing should be evaluat- ed individually. There is no doubt that both EHT and steam heat tracing have an important role to play in the different environments and industries they are developed and designed for. The key is to do proper homework, consult with the experts and install a system that will future proof your investment.

Giles Maynard is General Manager at eltherm South Africa. Tel: +27 (0) 11 883 2746 Email: rpaterson@eltherm.co.za

32 Electricity + Control

NOVEMBER 2017