Abstract
In the past, it has been a matter of concern to many people that natural gas which is available and sometimes flared to waste in desert places of the earth could not be conserved and economically transported as fuel to needy industrial countries.
To make such an operation possible, it is necessary to refrigerate the gas, which consists mainly of methane, to a temperature of — 260°F, under which condition it condenses to a liquid and shrinks to one-six-hundredth of its volume as a free gas. In this form and as a boiling liquid, it can be transported in insulated tanks built into ships specially designed for the purpose. Auto-refrigeration maintains the cargo at its boiling point and heat leakage through the insulation causes a small proportion of the cargo to boil off as gas. Such gas can either be re-liquefied by installing a refrigeration plant on board or be used as fuel in the ship's propulsion machinery.
The lecture describes the research and development work which led up to the full-scale trials in 1959 for the transportation of liquefied natural gas by sea in the Methane Pioneer. This is followed by a resume of the design requirements, building techniques and subsequent operating experience of the first two commercial ships which entered service in 1964 for the regular carriage of liquefied natural gas from Arzew in Algeria to Canvey Island in the Thames.
The design and engineering problems arising in these developments were unusual and varied, and they necessitated close co-ordination in the fields of cryogenics, metallurgy, chemical engineering and naval architecture. Not only were there problems associated with the physical properties of materials and insulants at low temperatures and the large contraction movements and strains induced by temperature change but there were problems of handling a boiling liquid continually releasing gas which, if trapped, could build up dangerous pressures. All these problems had to be faced on the large scale and assessed against the potential hazard of fire and explosion; in addition, they had to be superimposed on the somewhat unpredictable behaviour of a ship at sea whose design criteria were influenced more by experience and empiricism than by basic science.
The unusual and unprecedented nature of the project involving safety of life at sea, and affecting other users of rivers, ports and harbours, meant that from the outset there had to be close liaison and co-operation with Government Departments, Ministries, harbour and river authorities, regulatory bodies and local authorities. The successful conclusion of the project confirms the effectiveness of this co-operation and it affirms how the imagination, perseverance and technical skill of a team of engineers can be harnessed in endeavour and achievement.
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