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Inerting The Head Space In Ship Cargo Tanks

IP.com Disclosure Number: IPCOM000010091D
Publication Date: 2002-Oct-18

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The IP.com Prior Art Database

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Authors:
Kenneth T. McDonald

Abstract

The quality of some products, such as propylene oxide (PO), is affected by the presence of high oxygen content in the vapor space in storage vessel, such as ship tanks and cargo tanks. The consequences of oxygen exposure become especially pronounced when the exposure occurs for extended periods of time. Reducing the oxygen concentration in storage tanks and ship tanks during transit to less than about 500 parts per million (ppm) minimizes many of the detrimental effects of oxygen exposure. The oxygen concentration is typically reduced by purging and padding the tanks with an inert gas, such as nitrogen. However, it is especially difficult and time consuming to purge large ship tanks to the desired low oxygen concentration. Normally, the oxygen concentration is reduced using a continuous purge from bottom to top and cascaded from tank to tank on chemical tankers. This method is a time consuming and expensive task.