A heated issue

Deploying thermal insulation across oil and gas plant operations has always been considered a ‘necessary evil’. However, its actual value is really more virtuous than that.

When installed properly, insulation does an essential job, not least in ensuring that plants operate at safe temperatures. But another vital and cost saving application for insulation has presented itself in recent years: energy efficiency.

Obtaining energy efficiency has been the principal motivator for the European Industrial Insulation Foundation (EiiF) to commission research into potential cost savings in industry and launch its Technical Insulation Performance Check Programme (TIPCHECK). In turn, one of the EiiF’s founding partners, the industrial services company, Hertel, has implemented the use of infrared thermography as a way of identifying and measuring energy loss from industrial systems.

The impact of energy prices in the oil and gas sector, as with many process driven, manufacturing sectors, has become increasingly topical. And yet the approach to energy efficiency during the design and build phase of plants has been slow to change.  Those building plants do not tend to be the ones tasked with running plants and so are more focused on minimising the cost of construction than building in cost saving energy efficiency measures for the long term.  This leads companies to select particular plant locations to insulate but not others, resulting in heat and energy loss.

And yet, the payback on well managed energy efficiency is achieved, often in less than 12 months.

Planned insulation

It is crucial that industry changes the practice, that still exists, of designing plants without insulation designed and built in from the outset. Instead, the approach of involving insulation experts at the start of a new build project and specifying where insulation is required is much more effective than retrofitting insulation, which does nothing to combat the energy wasted already and also incurs additional installation costs.

What are the viable alternatives to a fundamental change in industry attitudes towards fitting insulation? An emissions trading scheme, in which companies obtain certificates for their CO₂ emissions, is a brilliant idea, but the existing price is too low. European industry has to compete with the rest of the world and too many regulations do not help its competitive advantage. High energy consuming companies need to implement an energy management system to benefit from tax subsidies for energy prices. In essence, the best approach is to implement ways of using less energy.

With this in mind, EiiF was created in February 2009 with the objective of raising awareness of the importance of installing sustainable insulation systems in industry to save energy and minimise CO₂ emissions. The EiiF’s mission is obvious and simple: it’s about changing industry habits.

But to do this, industry needs proof that it is worth changing. That proof came via a study commissioned by the EiiF with Ecofys, a consultancy agency in renewable energy, energy and carbon efficiency, energy systems and markets and climate policy.

The study into the energy and CO₂ savings potential of industrial insulation covered the 27 countries of the European Union and showed that savings from using insulation could amount to 620 PJ of energy_.   As a consequence, 15 coal fired power plants (500 MW) could be switched off.

The annual CO₂ reduction potential is 49 Mt. This is the equivalent to the CO₂ emissions of 10 million medium sized cars each running 12 500 km/y.

The study suggests that this savings potential exists across all regions, sectors, equipment and operating temperatures.

Committing to energy efficiency

What has become clear is that if companies want to increase energy efficiency, there has to be a top down management commitment to change, to establish an energy efficiency budget and to get employees aware and involved, especially those operating machinery and who know precisely where the insulation problems exist.

Starting an energy efficiency programme by improving insulation requires the conversation to change for the first time in 50 years: the industry needs to stop talking about price and start talking about quality.

A useful starting point is to understand the extent of energy loss across your plant operations. This can be done using experienced insulation engineers who have been trained to become energy auditors. The EiiF TIPCHECK programme enables insulation engineers to produce independent reports on the state of an industrial plant’s thermal insulation and recommend ways of saving energy, money and achieving payback on investment, often in less than a year.

The TIPCHECK programme requires insulation engineers to have at least 4 years experience in order to ensure a high standard of thermal energy audits, using data and software to make the calculations. But that is not all: TIPCHECK engineers have also helped identify safety issues on site, where surface temperatures are rising above allowed limits.  Energy audits and the use of thermography can be used also to gauge the general state of insulation. It can help to assess the integrity of insulated systems and help to find indications of corrosion under insulation.

Hertel began looking at thermal measurement and heat loss in industry more than five years ago, though analysing this problem in plant operations was not a common practice at the time. The aim was to provide a service that evaluated plant operators’ level of energy loss, suggest potential remedies and calculate how much cost they could save. Originally, the measurement, pioneered in the UK by Hertel, employed contact thermometers to detect energy loss.

Today, after years of building up experience and development of a method to estimate the actual heat loss from old insulated systems by Hertel's Plant Integrity department in the Netherlands, the chosen method is thermography using infrared (IR) cameras.

Using thermography

Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum and produce images of that radiation, called thermograms. Infrared radiation is defined between wavelengths of approximately two micrometres to
14 micrometres and is emitted from all mass as long as the temperature is above 0 Kelvin (-273 °C).

Infrared radiation is emitted according to the Stefan-Bolzmann law. The amount of radiation emitted per unit area increases with temperature. Therefore, thermography makes it possible to see variations in temperature.

Conducting infrared thermography in the field requires a high degree of knowledge. The engineer needs to understand infrared radiation and radiation physics.

A well trained IR thermographer will know that the amount of radiation produced from surfaces is not always equal to the amount expected from a black body radiator. This radiates an amount of energy calculated using Planck’s Law, by which the quantity of radiation from a surface is dependent on wavelength and temperature. Conversely, most surfaces do not behave as a black body surface, but as grey bodies, which emit less IR radiation. The ratio of the actually emitted IR radiation and the black body radiation is known as the surface’s emissivity. This is dependent on factors such as material, texture, angle of measurement, wavelength, temperature and geometry. A thermographer has to be aware of and deal with these factors in practice; looking at a surface and assessing the differences in emissivity from one location to the next. This information has to be input into the infrared camera.

In larger installations, insulation can be finished with shiny aluminium sheets which have low emissivity and are therefore hardly suitable for good IR measurements. Rather than seeing this as a major problem, it can be overcome by increasing the emissivity to make the IR radiation, and therefore the temperatures, more visible by treating the surface with paint.

Another factor the thermographer needs to consider is how radiation from the surroundings affects camera readings. This ‘disturbance’ will reflect back into the camera, so it is necessary to subtract the surrounding radiation to obtain an accurate reading. A thermographer needs to follow special procedures to evaluate the level of surrounding radiation in order to get a proper measurement. Thermography is not simply walking around with a camera! It involves a full appraisal of the surroundings and surfaces. Equally, a thermographic picture can be deceptive if the user isn’t clearly aware of how it works.

And yet, knowledge of thermography is still not sufficient: the engineer needs to have indepth knowledge of the system being appraised in order to judge the possible causes of differing temperatures across a system. This means understanding how the plant works in order to know why it was insulated, or not, and to interpret the thermogram produced as a result of IR measurement.

Thermography is a versatile technique that has applications in many areas of an industrial plant. It is used to determine energy losses through insulated or non-insulated systems but also to detect corrosion under insulation and liquid levels in tanks, for example.  However, it requires well trained personnel with excellent knowledge of thermography as well as what’s going on ‘under the surface’ to understand the extent of the problem in question.

The process at work

So, how does a TIPCHECK inspection process work in practice on a plant?

It begins with the plant manager wanting answer to the questions: can you tell me how much energy my plant is losing? What is the state of external and/or internal insulation? What do I need to do to remedy the problem during the plant shutdown period?

A site ‘walkabout’ will then determine the scope of work with the customer alongside an evaluation of thermograms in order to start calculating the amount of energy loss. The beauty of IR thermography is that measurements are taken from a distance without touching the system, allowing the normal running of the plant to continue. All measurements can be done relatively quickly because multiple items are usually captured in one IR image.

Thereafter, the TIPCHECK engineer will determine which insulation is needed to remedy the problem considering, for example, specific requirements for the insulation system, applied insulation materials, economy, the reduction of energy loss from the system, CO₂ emission reduction and, ultimately, the monetary savings that can be made. The length of payback time can also be established at this point. 

Chemical plant case study

• Small chemical plant: 37 IR pictures, 79 miscellaneous items and sizes operating at a constant temperature of approximately 110 °C.

• Duration of IR measurements: one day; duration of evaluation, calculation and final report approximately two days.

• Energy loss reduction determined at approximately € 28 000 per year when insulated using 50 mm thick mineral wool. Proven by measurement afterwards.

• Cost of installation approximately € 18 000, yielding a payback time of approximately seven months.

Conclusion

As the EiiF’s research has established, the energy saving potential is huge for any plant. Once the weaknesses in the system have been found, the work to remedy them can start immediately and the return on investment becoming tangible in a matter of months rather than years. The combination of this research, plus the necessary expertise and technology, is transforming what was once seen as a ‘necessary evil’ into untapped economic and environmental potential.

Written by Peter Stulen, Hertel, Netherlands and Andreas Guertler, EiiF, Switzerland.

Read the article online at: https://www.hydrocarbonengineering.com/special-reports/20062013/downstream_thermography_hertel_015/