Modifying an atmosphere in a chamber wherein separated nitrogen, carbon dioxide and water vapour is returned to the chamber

摘要

A method for modifying the composition of an atmosphere, comprising nitrogen, oxygen, carbon dioxide, water vapour and ethylene in a chamber 1, comprises a) pressurising (compressor 3) a portion of the atmosphere b) passing the pressurised atmosphere through an apparatus (e.g. membrane separation module 7) adapted to separate nitrogen from the atmosphere by means of semi-permeable membranes through which the components of the air diffuse at different speeds c) returning (arrow A) the separated nitrogen to the chamber d) passing the nitrogen-depleted pressurised atmosphere to an apparatus (e.g. a semi-permeable membrane device 17 or a pressure swing absorption apparatus) adapted to separate the carbon dioxide and the water vapour from the oxygen and ethylene e) returning (arrow B) at least a portion of the carbon dioxide and water vapour to the chamber, and f) venting (arrow C) the oxygen and ethylene to the environment. Apparatus for the method may include means 23 for sensing the composition of the atmosphere within the chamber and control means 25 adapted, in response to the sensed composition, to vary the amounts of carbon dioxide and water vapour returned to the chamber so as to produce and/or maintain a predetermined atmosphere composition within the chamber. The method may be used for controlling the atmosphere in containers used for storage and transportation of perishable produce such as fruit, vegetables and flowers.