Membrane plant: automatic control of
AssigneeThe BOC Group, Inc.
InventorMichael E. Garrett
Life of this patent
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Abstract
Air is separated in a vessel housing gas separation membranes. A flow control valve controls the passage of air to an inlet header of the vessel. The setting of the valve is adjusted in accordance with the level of oxygen impurity in product nitrogen leaving the vessel for an outlet header. A second flow control valve is provided and is of a kind whereby product nitrogen is able to be delivered at a constant flow rate over a range of different pressures upstream thereof. Accordingly, the apparatus is able to deliver nitrogen at a desired purity and flow rate.
Claims6
Apparatus for separating a gas mixture comprising a vessel housing semi-permeable membranes effective to separate the mixture via permeation into a permeate gas and a non-permeate gas and having a single inlet for the gas mixture to be separated, a first outlet for product gas and a second outlet for a gas stream of different composition from that of the product gas, a first flow control valve for controlling the flow of all of the gas mixture to be separated to said inlet, control means for adjusting the position of said first flow control valve in response to analysis of the composition of the product gas, and a second flow control valve for controlling the flow of product gas from the first outlet, said second control valve capable of delivering product gas at a constant flow rate over a range of different pressures upstream thereof, additionally including a valve regulating the pressure upstream thereof downstream of the second control valve so as to make it possible to maintain in operating of the apparatus a constant pressure intermediate the second control valve and the pressure regulating valve.
Dependencies are inferred from the claim text.