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Top 3 Things to Consider When Selecting Your Electrical Heat Tracing System
Dec 06, 2017

Top 3 Things to Consider When Selecting Your Electrical Heat Tracing System

After weighing the various options, many aspects/factors can influence the selection of the most appropriate control/monitoring solution for each project and application. The most effective solutions are often a blend of various combined technologies to achieve a balance between total installed costs(TIC), long-term benefits associated with the entire heat management system and total operating cost(TOC) during the life of the plant.

However, if you are managing a project that requires fluid temperature maintenance or electrical heat tracing, but are unsure where to start, please read on below:

Here are the top three factors to consider before selecting your next electrical heat tracing system:

  1. Determine the control and monitoring philosophy

An overarching control and monitoring philosophy must be established for a project before any products/systems can be selected.

Types/methods of control and monitoring need to be carefully selected based on various aspects:

  1. A) Process requirements
    -Temperatures
    -Flow path considerations
    -Alarm requirements
    -Upset conditions

    B) Maintenance strategy
    -Simplicity
    -Local or central monitoring
    -Location of installation
  2. C) Power distribution parameters
    -Location of panels
    -Substations
    -Cabling requirements
  3. D) Economical considerations (Optimization of TIC, TOC)

It might be worth considering incorporating a variety of monitoring options into the system design. The use of monitoring of the circuit integrity increases the overall system reliability as failures in the heating and power distribution systems can be reported to operations and maintenance personnel locally or at a central location and repairs can be carried out promptly, thus reducing any potential downtime to the heat tracing system.

  1. Choose the objective for your control systems

A variety of control systems has its own unique level of technical features and benefits, depending on the process requirements and the number of circuits required.

The main objective of your electrical heat tracing system could be:

  1. A) Frost Protection

Applied to fluids that must be kept above a minimum temperature - typically 5°C - e.g., For water lines and where moderate overheating of the fluid is not a major concern. They key objective of frost protection is to prevent water in water lines, pumps, and pipes from freezing.

  1. B) Broad Temperature Maintenance

Appropriate when the process temperature must be controlled within a moderate range. This is generally used for viscosity control to keep process fluids such as fuel oil flowing. It can be costly if oil does not always flow at the required rate during varying temperatures in the day/night hence the importance of heat tracing systems.

  1. C) Narrow Temperature Maintenance

Applied to fluids that must be kept within a narrow temperature range to maintain viscosity and prevent fluid or pipe degradation.

Typical examples include sulphur and acrylic acid lines.

  1. Select the appropriate method of control

The choice of the appropriate controller depends on whether the system is required to be controlled based on ambient or pipe/equipment surface temperature, which is dependent on the process requirements and, possibly, the equipment limitations.

Three methods of control for Electrical Heat Tracing (EHT) systems are further explained below:

  1. A) Ambient Sensing Control

Uses a simple on-off algorithm based on ambient temperature. It is more energy efficient as compared to self-regulating control because the heating circuit is energized only when the temperature descends below the required set point.

The control device can be either a mechanical thermostat or an electronic controller. Ambient thermostats are generally sufficiently accurate and reliable to provide an economical solution for most frost-protection applications.

  1. B) Proportional Ambient Sensing Control (PASC)

Uses an electronic controller that senses ambient temperature and continuously matches the heat input to the predicted heat loss that occurs due to changing ambient conditions.

A pre-programmed algorithm calculates the cycle time that the heating circuits will be energized to maintain the desired temperature. PASC is suitable for all broad temperature-control and many narrow temperature-control applications. Compared to line sensing, the use of PASC can significantly reduce the number of circuits, as flow paths do not need consideration and can help reducing total installed cost of a project whilst at the same time reducing energy consumption.

  1. C) Line Sensing Control

Line sensing control is based on the pipe/equipment temperature. With this option, each flow path has a separate circuit controlled by a mechanical line-sensing thermostat or electronic controller. The control unit turns on the heating circuit when the pipe temperature descends below the desired maintain temperature.

Line sensing offers the most accurate control for narrow temperature band applications.

Total installed cost of line sensing systems can be considerably higher than systems based on ambient temperature, as the average circuit length of the EHT system is typically significantly lower based on pipe lengths and possible flow paths.

Summary

We hope you have a better understanding about the points you may want to consider whilst selecting an electrical heat tracing system.

As an expert in the field of heat tracing with many years of experience and having completed various large-scale projects. Supermec provides both constant wattage and self-regulating trace heating systems. Get in touch with our friendly electrical heat tracing experts at sales@supermec.com or you can drop us a call at +65 68619522 to find out how we can assist you with your heat tracing needs and install a heat tracing system to help your business objectives today.


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