Thermal and acoustic insulation manufacturer Armacell is launching what claims to be an industry first with a low density thermal elastomeric foam insulation system which retains flexibility even at extreme cryogenic temperatures of ‑200 °C. Cryogenic processes which utilise these low temperatures and require technical thermal insulation materials include the freeze drying of foods, metal alloy production utilising liquid nitrogen, and the manufacture of some pharmaceutical and chemical products.
An area of growing significance is the freezing of large volumes of natural gas down to condensation temperatures (-162 °C), with the resultant liquid gas then having a reduced volume of less than 0.17% of the gaseous product. The costs of both storage and transportation of natural gas in a liquid form (LNG) are therefore considerably reduced. Armacell high performance insulation systems maintain the cryotechnical validity of this process throughout, from initial production to final regasification where the gas is fed into pipework for distribution.
Armacell have an established reputation for the supply of consistent, high-quality engineered foam materials. This includes-NBR (nitrile butadiene rubber) insulation products, suitable for refrigeration applications operating at temperatures down to -50 °C. With the introduction of their cryogenic elastomeric insulation system temperatures as low as -200°C can now be accommodated. This same system also has an upper temperature thermal limit of +125 °C, which ensures that internal surfaces of pipework, tanks and vessels can be safely subjected to steam or high temperature chemical cleaning without detriment to the insulation materials.
The Armaflex cryogenic insulation system utilises an inner layer of Armaflex LTD insulation with a completely new diene terpolymer where a much lower glass transition point has been achieved. This is the point where the mechanical behaviour of conventional NBR materials changes, with the rubber increasingly losing flexibility through hardening. For NBR materials this point is typically around –50 °C, whereas the Armaflex Cryogenic System maintains full strength and flexibility over a temperature range of -200 °C to +125 °C. This ensures that vibration and impacts can be absorbed, with the risk of cracking from extreme temperature cycling or mechanical strain considerably reduced. The closed cell material has a very low thermal conductivity and also a high resistance to water vapour transmission providing a ‘built-in’ vapour barrier. These characteristics reduce the risk of corrosion under insulation (CUI), while the flexible cryogenic foams, unlike rigid foams, also eliminate the need for expansion joints or additional vapour barriers to achieve installation savings.
When line temperatures are below -110 °C, the innermost layer of the Armacell cryogenic insulation system is fabricated with an outer reinforced-foil anti-abrasive layer. This provides added surface strength as well as enhanced protection from severe vibration and pipework movements.
The new Armaflex LTD product (used on the inner layer of the system), is supplied in pre-formed tubes of 2 metres in length. These provide a standard 25 mm thick insulation available in ten standard pipework sizes from 18 to 114 mm outside diameter. For tanks, vessels, pipework bends or junctions and intermediate valves etc, Armaflex LTD is also available in 1 metre wide x 4 metres long continuous sheets or covering rolls to provide tailored sizes to suit the specific installation requirements. For maximum effectiveness and protection against mechanical damage, it is recommended that all insulated pipework and equipment is protected with a final outer layer of contoured stainless steel sheeting or Armacell’s Arma-Chek R flexible covering material.
Armacell’s ArmaSound insulation is often incorporated as a key part of the cryogenic insulation system to attenuate noise from process pipework and contribute to the system’s thermal performance for an integrated thermal-acoustic solution.
The first major application of Armaflex Cryogenic insulation materials was for China’s prestigious LNG dock and terminal located in Nianyu Bay at the coast of Dalian City, Liaoning Province. Tankers up to a capacity of 200,000 m3 can be accommodated, and in the first phase which was completed at the end of 2011, 3 million tonnes of LNG are being converted into 4.2 billion m3 of natural gas annually. The Armacell high performance cryotechnical process has been successfully utilised on vaporisation pipes, pumps, valves and other fittings, to ensure that energy losses during the liquidation, storage and regasification processes are maintained at as low a level as possible.
Further information is available on request:
Armacell UK Ltd, Mars Street, Oldham, Lancashire OL9 6LY
Contact: Mr. Anthony Barnett
Telephone: 0161 287 7000
Fax: 0161 633 2685
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