Membrane Filter Element With Multiple Fiber Types

Abstract

A membrane filter element includes at least two cylindrical-shaped, fiber bundles, one of the fiber bundles containing first fibers fabricated to provide a selected first gas selectivity, a selected first gas permeability, or a selected first gas selectivity and permeability performance and arranged so a first gas permeate exits the membrane element; another of the fiber bundles containing second fibers fabricated to provide a selected second, different gas selectivity, a selected second different gas permeability, or a selected second gas selectivity and permeability performance and arranged so a second different gas permeate exits the membrane element. The different performance characteristics can reduce the number of membrane elements required for gas separation and to improve gas separation performance due to changing gas composition as the gas travels through the membrane element.

What is claimed is: 
     
         1 . A membrane element comprising:
 at least two concentric, cylindrical-shaped zones spanning a total height of the membrane element and surrounding a central longitudinal axis of the membrane element;   one of the zones defined by first fibers fabricated to provide a selected first gas selectivity and arranged so a first gas permeate exits an end of the membrane element;   another of the zones defined by second fibers fabricated to provide a selected second, different gas selectivity so a second different gas permeate exits an end of the membrane element.   
     
     
         2 . A membrane element according to  claim 1  wherein the first fibers are fabricated to provide a selected first gas permeability and the second fibers are fabricated to provide a second, different gas permeability. 
     
     
         3 . A membrane element according to  claim 2  wherein the first and second fibers are fabricated to provide, relative to one another, a different target CO 2  permeability. 
     
     
         4 . A membrane element according to  claim 2  wherein the first and second fibers are fabricated to provide, relative to one another, a different target H 2 S permeability. 
     
     
         5 . A membrane element according to  claim 1  relative to one another, a different target CO 2  selectivity. 
     
     
         6 . A membrane element according to  claim 1  wherein the first and second fibers are fabricated to provide, relative to one another, a different target H 2 S selectivity. 
     
     
         7 . A membrane element according to  claim 1  wherein the first and second fibers are fabricated to provide, relative to one another, a different target water dew pointing performance. 
     
     
         8 . A membrane element according to  claim 1  wherein the first and second fibers are fabricated to provide, relative to one another, a different target hydrocarbon dew pointing performance. 
     
     
         9 . A membrane element according to  claim 1  wherein depth of the zones differs from one another. 
     
     
         10 . A membrane element according to  claim 1  wherein at least one of zones is an innermost zone or an outermost zone of the membrane fiber element. 
     
     
         11 . A membrane element according to  claim 1  wherein the two zones are located adjacent one another. 
     
     
         12 . A membrane element according to  claim 1  further comprising the first and second fibers including hollow fibers. 
     
     
         13 . A membrane element according to  claim 1  wherein the first and the second different gas permeates exit a same end of the membrane element. 
     
     
         14 . A membrane element according to  claim 1  wherein the first and second different gas permeates mix with one another after exiting the same end. 
     
     
         15 . A method of treating a gas, the method comprising:
 flowing the gas through a membrane element containing at least two concentric, cylindrical-shaped zones spanning a total height of the membrane element and extending around the membrane element;   wherein one of the zones is defined by first fibers fabricated to provide a selected first gas selectivity and arranged so a first gas permeate exits an end of the membrane element; and   wherein another of the zones is defined by second fibers fabricated to provide a selected second, different gas selectivity and arranged so a second different gas permeate exits an end of the membrane element.   
     
     
         16 . A method according to  claim 15  wherein the first and second fibers are fabricated to provide a selected first gas permeability and the second fibers are fabricated to provide a second, different gas permeability. 
     
     
         17 . A method according to  claim 15  wherein the first and second fibers are fabricated to provide, relative to one another, a different target water dew pointing performance. 
     
     
         18 . A method according to  claim 15  wherein the first and second fibers are fabricated to provide, relative to one another, a different target hydrocarbon dew pointing performance. 
     
     
         19 . A method according to  claim 15  wherein the first and second fibers include hollow fibers. 
     
     
         20 . A method according to  claim 15  further comprising mixing the first and second different gas permeates with one another after exiting a respective end of the membrane element.