LNG Industry asked several companies to discuss some key factors regarding LNG insulation.
Q1. What factors are considered when selecting insulation for the LNG process?
Anatoli Kogan, Alkegen
LNG is a natural gas that becomes liquid at a very cold temperature (approximately -162°C [-260°F]). Due to the very large temperature differential, there is a considerable heat inleak from ambient environment to the outer walls of LNG vessels or pipes. Transferring and storing LNG at such extreme temperature requires an efficient insulation to reduce the evaporation losses as well as to prevent moisture/ice build-up on the outside wall which can lead to corrosion. In addition to safety and cost, there are multiple factors that should be considered when selecting insulation for LNG vessels and piping required to meet the specified boil-off rate or pressure build up. These include:
- Thermal efficiency.
- Insulation thickness and weight.
- Dimensional stability.
- Application method.
- Overall size/footprint.
- Maintenance frequency.
Mark Krajewski, Aspen Aerogels Inc.
LNG facilities are some of the most technically challenging applications to insulate, and there are numerous hot and cold thermal design considerations. On the cold side, the designer is nearly always interested in minimising both heat gain into process piping and equipment and the resulting boil-off gas. There is also a desire to minimise condensation formation on the exterior of the insulation jacket. On the hot portion of LNG processes, heat loss is often important, and when process piping and equipment are in areas that humans can access, personnel protection against burns is also specified.
A second consideration is that many portions of LNG liquefaction facilities emit unacceptable levels of sound. Because these sounds must be mitigated, the insulation system will have both thermal and acoustical design goals.
The third major consideration is protection from fire and cryogenic liquid spills and combinations of these hazards. The state-of-the-art LNG facility needs to have its thermal insulation packages possibly protect against pool fire, jet fire and cold splash exposures in combination with thermal and acoustical requirements. Certainly not the rule-of-thumb ‘one and done’ cold service tables of the past.
Melvin Rasco, Johns Manville
Several factors should be considered when selecting insulation for LNG, the major one being how well the insulation prevents surface condensation. Others include the desired service life of the system, the physical environment that the system must endure, and the operating conditions of the system. A well thought out maintenance plan is also important. Moreover, it is imperative that all applicable standards and specifications are followed.
Per Ivar Nikolaisen, LNT Marine Pte., Ltd
There are several factors to consider when selecting insulation for LNG installations. For the marine sector, the first consideration is compliance with IMO IGC or IGF code, class rules, and other regulatory authorities. The second consideration is the operational environment and the type of tank or process. The third consideration is the required thermal conductivity or total heat ingress in relation to the available space for insulation.
Jack Blundell, ROCKWOOL Technical Insulation
Selecting the right insulation for LNG storage requires careful consideration of several operational factors. This includes the insulation’s purpose, the operating temperature range, tank design, the ambient conditions, and corrosion considerations.
For cold applications (-161°C [-258°F] or below) such as LNG tankage, insulation should have low thermal conductivity to avoid heat gain and prevent the liquefied gas in the tank from converting back to its gaseous state.
Insulation systems should be selected that can efficiently protect tanks and other LNG infrastructure operating at cryogenic conditions from vapour drive. LNG plants are also known for generating lots of noise. Insulation systems with effective acoustic properties should be considered to bring noise to an acceptable level.
Preventing corrosion under insulation (CUI) due to water ingress is a major factor. Insulation and the outer jacketing should be chosen based on their ability.
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Read the article online at: https://www.lngindustry.com/special-reports/06122023/insulation-qa/
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