Development of mass production type rigid polyurethane foam for LNG carrier using ozone depletion free blowing agent

• Published in: Cryogenics (Guildford) 2016-12, Vol.80, p.44-51
• Main Authors: Lee, Yeongbeom, Baek, Kye Hyun, Choe, Kunhyung, Han, Chonghun
• Format: Article
• Language: English
• Subjects: Additives; Blowing agents; Boil-off rate; Compressive strength; Energy conservation; Energy consumption; Environmental protection; Environmental regulations; Heat transfer; Hydrochlorofluorocarbons; Hydrofluorocarbons; Liquefied natural gas; LNG carrier; Mass production; Natural gas; Ozone; Ozone depletion; Ozone depletion potential; Ozonosphere; Perfluoroalkane; Polyurethane; Polyurethane foam; Propulsion; Specifications; Thermal conductivity; Thermal shock
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2016.09.002

•Rigid-PUFs applicable to an insulator for LNG carriers were developed by using ODP free blowing agents.•Effects of additives on rigid-PUF prepared with ODP free blowing agents were clarified.•The BOR of LNG carrier using mass production rigid-PUF reaches below 0.12vol%/day.•The mass production type PUF are evaluated in terms of temperature dependency of mechanical properties and application to carg containment system for a LNG carrier. Nowadays the price of natural gas has become higher and the efficiency of propulsion system of liquefied natural gas (LNG) carriers has improved. Due to these trends, required boil-off rate (BOR) for LNG carrier has been lowered from 0.15%/day to 0.12%/day for conventional LNG carriers with sizes between 125,000m3 and 170,000m3. This requirement of BOR can be satisfied by using a rigid polyurethane foam (PUF) blown by 1,1-dichloro-1-fluoroethane (HCFC-141b) as an insulator. However, ozone depletion potential (ODP) of HCFC-141b requires alternative blowing agents with zero ODP such as hydroflurocarbons (HFCs) because of tougher environmental regulations. This paper introduces use of HFCs and additives to enhance properties of rigid PUFs under a mass production environment. Among the additives, perfluoroalkane (PFA) reduces thermal conductivity down to 12% and increases compressive strength up to 15% of a rigid PUF prepared in a laboratory scale. Based on this result, a mass production type rigid PUF is manufactured and is evaluated for BOR, mechanical strengths over operation temperature range, and thermal shock stability for LNG carriers. The BOR of the manufactured rigid PUF is below 0.12%/day, which satisfies the recent BOR specification for LNG carriers. The other required properties are also met the specifications for a conventional LNG carrier. Consequently, it is expected that the results in this paper will bring low BOR (