Removal of carbon dioxide from air

Abstract

An air/liquid exchanger comprising an open-cell foam 102 supporting a liquid sorbent. The exchanger may be used for removing trace gaseous components from the air.

1 . A device for absorbing or adding gaseous components from or to a gas stream, which comprises one or more foam elements made from open cell foams wettable by a liquid sorbent, where the foam elements include open passageways and/or a plurality of foam elements are arranged spaced from one another to form open passageways for gas to flow through or around, whereupon the liquid sorbent on the foam may interact with the gas to either absorb gaseous components or emit volatile components into the gas stream as the gas stream is passed through said passageways. 
   
   
       2 . The device as claimed in  claim 1 , further including structural support to hold the foam elements in place. 
   
   
       3 . The device as claimed in  claim 2 , whereupon the structural support is external to the foam elements. 
   
   
       4 . The device as claimed in  claim 2 , wherein the structural support is internal to the foam elements. 
   
   
       5 . The device as claimed in  claim 1 , wherein the foam elements are pre-wetted with liquid sorbent prior to use. 
   
   
       6 . The device as claimed in  claim 1 , further including a fluid handler for periodically pouring liquid sorbent over the foam to displace spent liquid sorbent with fresh liquid sorbent and for collecting spent liquid sorbent drained from the foam. 
   
   
       7 . The device as claimed in  claim 1 , further including a fluid handler for continuously adding liquid sorbent to the foam and for collecting spent liquid sorbent drained from the foam. 
   
   
       8 . The device as claimed in  claim 1 , wherein the foam is shaped to optimize uptake and drainage of liquid sorbent by funneling the flow. 
   
   
       9 . The device as claimed in  claim 1 , wherein macroscopic surfaces of the foam not used for gas contact are sealed at least in part. 
   
   
       10 . The device as claimed in  claim 9 , wherein surfaces of the foam not used for gas contact are collapsed to close open cells and thereby create impermeable protective surfaces. 
   
   
       11 . The device as claimed in  claim 9 , wherein surfaces of the foam not used for gas contact are covered at least in part with a fluid sorbent impenetrable material. 
   
   
       12 . The device as claimed in  claim 11 , wherein the coating comprises a film. 
   
   
       13 . The device as claimed in  claim 11 , wherein the coating comprises a formed in-situ coating. 
   
   
       14 . The device as claimed in  claim 1 , wherein passageways through the foam are arranged in a manner to allow the gas to flow in a straight line so that the gas flow maintains a substantially laminar flow with minimum flow resistance. 
   
   
       15 . The device as claimed in  claim 1 , wherein the foam comprises an open cell foam wettable by water. 
   
   
       16 . The device as claimed in  claim 15 , wherein the open cell foam comprises a floral retention foam. 
   
   
       17 . An installation for absorbing gaseous impurities from a gas stream, comprising two or more devices as claimed in  claim 1 , stacked such that fluid can be passed from one to the next. 
   
   
       18 . An installation as claimed in  claim 17 , wherein fluid flow drained from one device is introduced as a fluid input to another device. 
   
   
       19 . The method for capturing carbon dioxide from air, which comprises providing an open pore foam material, wetted with a sorbent, and passing an air stream in contact with wetted areas of said foam. 
   
   
       20 . The method of  claim 19 , wherein the foam is wetted with sorbent prior to use. 
   
   
       21 . The method of  claim 19 , including the step of periodically refreshing the foam with sorbent. 
   
   
       22 . The method of  claim 19 , including the step of crushing the foam and recovering liquid sorbent therefrom. 
   
   
       23 . The method of  claim 19 , wherein the sorbent comprises a caustic solution. 
   
   
       24 . The method of  claim 23 , wherein the sorbent comprises a liquid solution of sodium hydroxide. 
   
   
       25 . The method of  claim 23 , wherein the sorbent comprises a liquid solution of potassium hydroxide or calcium hydroxide. 
   
   
       26 . The method of  claim 19 , wherein the sorbent comprises a solid caustic impregnated within the foam during manufacture. 
   
   
       27 - 60 . (canceled) 
   
   
       61 . Apparatus for enhancing contact between a trace gas in a gas stream and a liquid or solid sorbent which comprises an open and/or reticulated cell foam having flow channels that are large relative to the pore size for guiding the gas stream along low resistance pathways through the foam and where the open cell foam is filled predominantly with gas and where at least some of the gas volumes inside the foam are interconnected with each other and are connected to the gas flow in the channels, and a sorbent for the selected gas either coating the foam or forming liquid droplets caught inside the foam. 
   
   
       62 . The apparatus as claimed in  claim 61 , wherein the sorbent comprises a suspension of solid sorbent particles wetting the foam. 
   
   
       63 . The apparatus as claimed in  claim 61 , wherein the sorbent comprises solid sorbent particles dried on the foam. 
   
   
       64 . The apparatus as claimed in  claim 61 , wherein the foam is traversed by straight channels. 
   
   
       65 . The apparatus as claimed in  claim 64 , wherein the channels are cylindrical. 
   
   
       66 . The apparatus as claimed in  claim 61 , wherein the channels have complex shaped walls creating complex flows for reducing the thickness of the boundary layer between the foam and the channels. 
   
   
       67 . The apparatus as claimed in  claim 61 , wherein the foam comprises a hydrophobic material. 
   
   
       68 . The apparatus as claimed in  claim 61 , wherein the foam comprises a hydrophilic material. 
   
   
       69 . The apparatus as claimed in  claim 61 , wherein the foam comprises both hydrophilic and hydrophobic materials. 
   
   
       70 . The apparatus as claimed in  claim 63 , wherein the sorbent particles are adhered to or are immobilized in the cage structure of the foam. 
   
   
       71 . The apparatus as claimed in  claim 69 , wherein the solvent comprises particles of opposite water wettability. 
   
   
       72 . The apparatus as claimed in  claim 61 , wherein the sorbent is washed into the foam as a suspension. 
   
   
       73 . The apparatus as claimed in  claim 61 , wherein the sorbent is captured in-situ in the foaming process. 
   
   
       74 . The apparatus as claimed in  claim 61 , wherein the pore size is between 0.1 mm and 1 mm. 
   
   
       75 . The apparatus as claimed in  claim 62 , further including a drive mechanism for rotating the foam structure partially submerged in a supply of sorbent fluid. 
   
   
       76 . The apparatus as claimed in  claim 75 , wherein the foam includes channels running traversely to the axis of rotation. 
   
   
       77 . The apparatus as claimed in  claim 61 , wherein the foam comprises a resiliently deformable foam. 
   
   
       78 . The apparatus as claimed in  claim 77 , and further comprising one or more rollers or plates for selectively compressing the foam to express excess sorbent from the foam or to distribute sorbent within the foam. 
   
   
       79 . The apparatus as claimed in  claim 78 , wherein the rollers have structured surfaces. 
   
   
       80 . The apparatus as claimed in  claim 79 , wherein the rollers have ridges running parallel to the roller axis or in the circumferential direction. 
   
   
       81 . The apparatus as claimed in  claim 79 , wherein the rollers have indentations and protrusions of different shapes. 
   
   
       82 . The apparatus as claimed in  claim 78 , wherein the rollers are fixedly located and the foam is moved back and forth between the rollers. 
   
   
       83 . The apparatus as claimed in  claim 78 , wherein the foam is fixedly located, and the rollers are moved relative to the foam. 
   
   
       84 . The apparatus as claimed in  claim 78 , wherein spacing between the rollers or plates is adjustable in order to control fluid expression or fluid distribution in the foam. 
   
   
       85 . The apparatus as claimed in  claim 78 , further comprising a device for supplying fresh sorbent either adjacent the top of the foam or ahead of the moving rollers. 
   
   
       86 . The apparatus as claimed in  claim 78 , wherein the apparatus includes a continuous loop of foam stretched over two opposing rollers and where one end of the loop is immersed in a supply of a liquid sorbent. 
   
   
       87 . The method as claimed in  claim 19 , including the step of adding surfactants to the sorbent to adjust fluid retention of the foam.