Apr-2013

Insulating tank terminals

Energy-efficient tank insulation systems result in lower energy costs, less maintenance, and a prolonged lifespan of contents and equipment

PETER BOON
Pentair Thermal Management

Article Summary

Storage tank insulations are becoming more important than ever. Global CO2 emissions have risen dramatically over the past few years and are set to increase by up to 90% by 2050 should industrial emissions remain unchecked.¹ Under pressure from the EU’s ambitious “20-20-20” target, tank terminal operators are increasingly looking for effective insulation systems to limit costs and prepare for new legislation. This article discusses the different insulation solutions available and establishes how tank operators can effectively reduce energy costs and cut CO2 emissions.

Thermal insulations with long-term benefits
Although thermal insulation systems are easily installed and highly cost effective, studies have revealed that industrial insulations are often either poorly maintained or non-existent, resulting in excessive heat losses.² However, with the EU’s ambitious plans to cut greenhouse gas emissions by 20% compared to its 1990 levels by 20203 and a carbon tax more likely, industrial insulation solutions can play a key role in achieving energy targets. Primarily used for products that require storage at high temperatures, tank insulations provide a number of benefits.

One of the most obvious advantages of effective thermal insulation is the reduced loss of heat. By wrapping tanks in materials with low thermal conductivity, heat within the tank is retained more effectively. As a result, tank operators need to use considerably less heat- generating equipment to produce the same amount of heat. According to a study commissioned by the European industrial insulation Foundation (EiiF), improving insulation to a cost-effective level would avoid 66% of current heat loss, which amounts approximately to the annual energy consumption of 10 million households.² This, in turn, would also have an impact on carbon emissions, resulting in a potential reduction of 49 Mt/y of CO2. As prices for energy rise, these cost-saving potentials will become even more obvious, making energy-efficient insulations an attractive investment for the future.

Although, thermal insulation is primarily used for tanks that store temperature-sensitive materials, it can, in fact, conserve the quality of many substances and offers an effective protection against frost and fire. Furthermore, it can significantly reduce the effects of thermal stresses on the tank itself, protecting its structure from external forces, such as rain, wind and abrupt temperature fluctuations. The results are lower energy costs, less maintenance and a prolonged lifespan of contents and equipment.

Finding the solution
When it comes to choosing a system, tank operators have a number of insulation solutions available. Depending on the contents, external environment and required temperature level, some solutions might be less or more suitable than others. Whatever the project, involving insulation engineers in the planning process is vital and will ensure that the energy-saving potential of the technology is maximised.

One of the established insulation materials available is mineral wool. Often used to insulate buildings, pipes and storage tanks, mineral or stone wool has become one of the most common insulation materials. While demonstrating good sound absorption, fire resistance and reasonable thermal behaviour, mineral wool insulations require a complicated and lengthy installation process. In particular for larger tanks, a complex scaffolding system is required to set up the outer insulation structure. Conventional tank insulation systems with mineral wool may also require extensive welding of insulation support rings and insulation pins, next to the need for installing banding bars and screws that cause increased heat loss and increased tank builder’s cost. While this might not cause major concerns at the early stages of a project, it does, however, result in significant downtime once the tank is in service, making it less suitable for retrofit insulations.

To minimise the installation impact on active tanks, some tank terminal operators are turning to polystyrene or polyurethane foam insulations. Although these foams can be easily sprayed onto the walls of a tank and will provide instant thermal insulation, the lifespan of the material is comparatively low. Easily accessible to rodents and birds, spray foam insulation needs to be inspected regularly to ensure the system remains fully sealed. Furthermore, spray foam can only be installed in completely dry conditions and it can encourage mould growth if not applied properly. Recent findings also suggest that polystyrene foam does not demonstrate the same stability as other materials when exposed to fire.⁴

Locking in the heat
An effective and improved alternative to conventional systems and spray foam systems consists of prefabricated panels constructed by laminating insulation material to a metal jacket. These are robust, double-locking, vertical-standing seam insulation panels that can be easily fitted around a tank. Pentair’s insulation system is called Trac-Loc.

Due to the use of insulation materials with a much lower thermal conductivity value compared to mineral wool or polystyrene foam, the heat loss is highly reduced, resulting in substantial energy savings and, in direct relation to that, a reduction in the carbon footprint. The preferred insulation material is polyisocyanurate (PIR), a non-fibrous closed cell structure material resulting in minimised water/fluids absorption and degeneration, a superior low lambda value, and a long and stable lifetime (see Figure 2).

Trac-Loc panels are usually prefabricated off-site in a controlled workshop environment, making the installation less dependent on weather conditions. They are then assembled on-site using a hanging basket or cherry picker, eliminating the use of scaffolding. As a result, the installation process is safer and can be completed much quicker than conventional methods. Time spent on-site will be a deciding factor for many operators, in particular those looking to retrofit terminals. Insulation panels can be easily fitted during scheduled maintenance work or when tank contents are being replaced, avoiding costly disruptions. As the panels are customised and can have lengths up to 12 metres, the amount of horizontal joints is reduced to the minimum. The system allows for individual panels to be easily replaced should they become damaged. The fully locked seam system also eliminates water penetration, reducing the occurrence of under-insulation corrosion and offering consistent performance levels throughout its life (see Figure 3). As a result, the system hardly requires any maintenance and has a much higher lifespan than conventional systems.