Electrolyzer

Abstract

An electrolysis cell includes an inner chamber containing a stack of porous anode and cathode plates with separators therebetween. Electrolyte is circulated through the porous anodes and cathodes in the inner chamber to generate hydrogen and oxygen gas. A plurality of electrolysis cells can be mounted together to form an electrolyzer unit.

1 . An electrolysis cell for producing hydrogen and oxygen from a concentrated liquid electrolyte, the cell comprising: a housing, a plurality of porous cathode plates, a plurality of porous anode plates disposed between the cathode plates, a hydrogen gas conduit in fluid flow communication between the cathode plates and a hydrogen gas outlet port on the housing; an oxygen gas conduit in fluid flow communication between the anode plates and an oxygen gas outlet port on the housing, an electrolyte inlet and an electrolyte outlet, the electrolyte inlet and the electrolyte outlet arranged such that electrolyte flows through the anode plates and the cathode plates and a separator disposed between each adjacent anode plate and cathode plate, an end separator disposed adjacent each of the electrolyte inlet and the electrolyte outlet, the end separators being selected to be permeable to electrolyte and impermeable to hydrogen gas and oxygen gas.  
     
     
         2 . The electrolysis cell of  claim 1  wherein there are four anode plates and four cathode plates and they are arranged from end to end as cathode, anode, anode, cathode, cathode, anode, anode, cathode.  
     
     
         3 . The electrolysis cell of  claim 1  wherein there is a pressure differential between the electrolyte inlet and the electrolyte outlet such that a flow therebetween is generated.  
     
     
         4 . The electrolysis cell of  claim 3  further comprising a second electrolyte inlet and wherein there is a pressure differential between the inlets.  
     
     
         5 . The electrolysis cell of  claim 3  further comprising a second electrolyte outlet and wherein there is a pressure differential between the outlets.  
     
     
         6 . The electrolysis cell of  claim 1  wherein the electrolyte inlet and the electrolyte outlet form part of an electrolyte flow path and the potential difference between any electrode and any exposed conductive surface in the electrolyte flow path outside of the end separators is maintained below 1.2V.  
     
     
         7 . The electrolysis cell of  claim 1  wherein at least one of the inlet or the outlet is formed as a labyrinth having at least one bend therein to effectively increase its length.  
     
     
         8 . The electrolysis cell of  claim 1  wherein there is a high pressure electrolyte inlet, a low pressure electrolyte inlet, a high pressure electrolyte outlet and a low pressure electrolyte outlet.  
     
     
         9 . The electrolysis cell of  claim 1  further comprising an electrolyte diffusing member positioned adjacent the electrolyte inlet to diffuse the flow of electrolyte passing through the inlet.  
     
     
         10 . The electrolysis cell of  claim 9  wherein the electrolyte inlet is positioned to supply electrolyte in a flow path through a plane of diffusing member.  
     
     
         11 . The electrolysis cell of  claim 1  wherein the separator comprises passages therethrough sized to permit the passage of electrolyte but to exclude the passage of hydrogen gas and oxygen gas bubbles.  
     
     
         12 . The electrolysis cell of  claim 11  wherein the separator is microporous, hydrophilic plastic.  
     
     
         13 . The electrolysis cell of  claim 1  wherein the anode plates and the cathode plates are gas diffusion electrodes including hydrophobic passages for transport of gas therethrough and hydrophilic passages for transport of electrolyte therethrough.  
     
     
         14 . The electrolysis cell of  claim 1  wherein the anode plates include at least some adjacent anodes formed integral as one unit by folding the anodes to create a folded edge to prepare them for assembly and forming an anode contact surface at the folded edge.  
     
     
         15 . The electrolysis cell of  claim 14  wherein the anode contact is formed by dipping the folded edge into molten contact material.  
     
     
         16 . An electrolyzer unit for producing hydrogen and oxygen from a concentrated liquid electrolyte, the unit comprising: 
 a housing;    two electrolysis cells within the housing, each electrolysis cell including an inner chamber and disposed therein a plurality of porous cathode plates, a plurality of porous anode plates disposed therein, the porous cathode plates alternating between the anode plates and a separator disposed between each adjacent anode plate and cathode plate, the separators being selected to be permeable to electrolyte and impermeable to hydrogen gas and oxygen gas bubbles; a hydrogen gas conduit in fluid flow communication with the cathode plates and a hydrogen gas outlet port on the housing; an oxygen gas conduit in fluid flow communication with the anode plates and an oxygen gas outlet port on the housing, a secondary electrolyte inlet and a secondary electrolyte outlet, the secondary electrolyte inlet and the secondary electrolyte outlet arranged such that electrolyte flows through the anode plates and the cathode plates, a separator disposed adjacent each of the secondary electrolyte inlet and the secondary electrolyte outlet;    a main electrolyte inlet conduit to supply electrolyte to the cells and extending between the secondary electrolyte inlets of the two electrolysis cells; and    a main electrolyte outlet conduit through which electrolyte is evacuated from the cells, the main electrolyte outlet conduit extending between the secondary electrolyte outlets of the two cells;    the main electrolyte inlet conduit and the secondary electrolyte inlets together being formed to maintain galvanic separation of at least 95% between the two cells; and    the main electrolyte outlet conduit and the secondary electrolyte outlets together being formed to maintain galvanic separation of at least 95% between the two cells.    
     
     
         17 . The electrolyzer unit of  claim 16  wherein the at least 95% galvanic separation is achieved by forming the main electrolyte inlet conduit and the secondary electrolyte inlets to have a combined length at least twenty times greater than the effective distance between adjacent anode plates and cathode plates in the cell.  
     
     
         18 . The electrolyzer unit of  claim 16  wherein at least one of the secondary electrolyte inlets is formed as a labyrinth having at least one bend therein to effectively increase their length.  
     
     
         19 . The electrolyzer unit of  claim 16  wherein the secondary electrolyte outlets are formed as labyrinths each having at least one bend therein to effectively increase their length.  
     
     
         20 . The electrolyzer unit of  claim 16  wherein the secondary electrolyte inlets include ports opening into the electrolysis cell inner chamber and at least one of the ports extend at least ⅔ of the width of the electrolysis cell inner chamber.  
     
     
         21 . The electrolyzer unit of  claim 20  wherein the secondary electrolyte outlets include ports opening into the electrolysis cell inner chamber and at least one of the ports extend at least ⅔ of the width of the electrolysis cell inner chamber.  
     
     
         22 . The electrolyzer unit of  claim 21  wherein the secondary electrolyte outlet ports are positioned above, as determined by gravity, the secondary electrolyte inlet ports.  
     
     
         23 . The electrolyzer unit of  claim 16  wherein there is a pressure differential in each cell between the secondary electrolyte inlet and the secondary electrolyte outlets such that a flow therebetween is generated.  
     
     
         24 . The electrolyzer unit of  claim 16  wherein there is a pressure differential between the secondary electrolyte outlets in each cell such that there is a lower pressure outlet and a higher pressure outlet and a greater flow passes through the lower pressure outlet than the higher pressure outlet.  
     
     
         25 . The electrolyzer unit of  claim 24  wherein there are a first and a second main electrolyte outlet conduit, the first main electrolyte outlet conduit extending between the higher pressure outlets of the two cells and the second main electrolyte outlet conduit extending between the lower pressure outlets of the two cells.  
     
     
         26 . The electrolyzer unit of  claim 16  further comprising in each of the at least two cells a second secondary electrolyte inlet and wherein there is a pressure differential between the two secondary inlets in each cell.  
     
     
         27 . The electrolyzer unit of  claim 26  wherein there are a first and a second main electrolyte inlet conduit, the first main electrolyte inlet conduit extending between the first secondary electrolyte inlets of the two cells and the second main electrolyte inlet conduit extending between the second secondary electrolyte inlets of the two cells.  
     
     
         28 . The electrolyzer unit of  claim 16  the potential difference between any electrode and any exposed conductive surface in the electrolyte flow path outside of the separators is maintained below 1.2V.  
     
     
         29 . The electrolyzer unit of  claim 16  wherein no reaction surface of any anode plate or cathode plate is exposed in an electrolyte conduit, inlet or outlet.  
     
     
         30 . The electrolyzer unit of  claim 16  wherein the cells are formed by arranging the anode plates, cathode plates and separators in a stack and injecting housing material thereabout and the main electrolyte inlet conduit and the main electrolyte outlet conduit extending through the cell selected such that no anode or cathode gas generation surface being exposed in the main conduits.  
     
     
         31 . An electrolyzer unit for producing hydrogen and oxygen from a concentrated liquid electrolyte, the unit comprising: 
 a housing;    a first electrolysis cell within the housing and a second electrolysis cell within the housing, each electrolysis cell including a plurality of porous cathode plates, a plurality of porous anode plates disposed between the cathode plates, a hydrogen gas conduit in fluid flow communication with the cathode plates and a hydrogen gas outlet port on the housing; an oxygen gas conduit in fluid flow communication with the anode plates and an oxygen gas outlet port on the housing, a first and a second electrolyte inlet and a first and a second electrolyte outlet, the electrolyte inlets and the electrolyte outlets arranged such that electrolyte flows through the anode plates and the cathode plates and a separator disposed between each adjacent anode plate and cathode plate, a separator disposed adjacent each of the electrolyte inlets and the electrolyte outlets, the separators being selected to be permeable to electrolyte and impermeable to hydrogen gas and oxygen gas bubbles;    an electrolyte inlet conduit to supply electrolyte to the cells and extending between the electrolyte inlets of the first and the second electrolysis cells; and    an electrolyte outlet conduit through which electrolyte is evacuated from the cells, the electrolyte outlet conduit extending between the electrolyte outlets of the first and the second electrolysis cells;    an electrolyte diffusion assembly positioned between the first and the second cells and forming a wall therebetween, the electrolyte diffusion assembly defining the first electrolyte inlet and the first electrolyte outlet of the first electrolysis cell and the second electrolyte inlet and the second electrolyte outlet of the second electrolysis cell.    
     
     
         32 . The electrolyzer unit of  claim 31  wherein the electrolyte inlet conduit and the electrolyte outlet conduit are each formed to maintain galvanic separation of at least 95% between the cells.  
     
     
         33 . The electrolyzer unit of  claim 32  wherein the at least 95% galvanic separation is achieved by forming the electrolyte inlet conduit and the electrolyte outlet conduit such that the shortest electrolyte path length between an electrode in the first cell and an electrode in the second cell is at least twenty times greater than the effective distance between adjacent anode plates and cathode plates in one cell.  
     
     
         34 . The electrolyzer unit of  claim 31  wherein the electrolyte inlet conduit includes a portion passing through the electrolyte diffusion assembly and formed as a labyrinth having at least one bend therein to effectively increase its length.  
     
     
         35 . The electrolyzer unit of  claim 31  wherein the electrolyte inlet conduit includes a portion passing through the electrolyte diffusion assembly and formed as a labyrinth each having at least one bend therein to effectively increase their length.  
     
     
         36 . An electrode for use in an electrolysis cell, the electrode comprising: a porous conductor having an outer surface, an active layer material on the outer surface of the porous conductor, a catalyst dispersed within the active layer material, and a contact for electrical connection to a power source, the contact molded into contact with the porous conductor.  
     
     
         37 . The electrode of  claim 36  wherein the contact is formed of tin.  
     
     
         38 . The electrode of  claim 36  wherein the contact is connected by molding to contacts of other electrodes of the same type within the electrolysis cell.  
     
     
         39 . The electrode of  claim 36  wherein the conductor is integral with a second electrode folded to be in side by side relation with the electrode.  
     
     
         40 . The electrode of  claim 39  wherein the conductor forms a folded edge between the electrode and the second electrode and the contact is connected at the folded edge.