Electrolysis system

Abstract

An electrolysis cell system ( 100 ) for producing hydrogen and oxygen from water comprising: at least one electrolysis cell ( 101 ) including a membrane electrode assembly ( 102 ) which comprises at least one pair of gas permeable electrodes ( 107, 109 ) comprising an anode ( 107 ) and a cathode ( 109 ), and an ion conductive electrolyte ( 108 ) arranged between each pair of anode ( 107 ) and cathode ( 109 ); an electrode gas space ( 104, 106 ) on the non-electrolyte side of each electrode ( 107, 109 ) comprising an anode gas space ( 104 ) and a cathode gas space ( 106 ), at least one electrode gas space ( 104 ) including an inlet ( 130 ) and an outlet ( 132 ); a recirculating loop ( 143 ) for recirculating at least a portion of produced oxygen product gas from the outlet ( 132 ) of at least one electrode gas space ( 104 ) to the inlet ( 130 ) of the respective electrode gas space ( 104 ) and through the respective electrode gas space ( 104 ); a water supply vessel ( 142 ) in fluid communication with the recirculating loop ( 143 ), the water supply vessel ( 142 ) vaporising water from a water supply ( 144 ) utilising heat of vaporisation provided by the respective product gas in the recirculating loop ( 143 ) and feeding said water vapour into the recirculating loop ( 143 ); and a heat transfer arrangement ( 105 ) for transferring heat between the membrane electrode assembly ( 102 ) and gas in the anode gas space ( 104 ) located in the electrode gas space ( 104 ) fluidly connected to the recirculating loop through the inlet and outlet thereof, wherein the heat transfer arrangement ( 105 ) is in contact with the membrane electrode assembly ( 102 ) and also allows for gas circulation between the membrane electrode assembly ( 102 ) and the respective gas space ( 104 ).

1 .- 26 . (canceled) 
     
     
         27 . An electrolysis cell system for producing hydrogen and oxygen product gas from water comprising:
 at least one electrolysis cell including a membrane electrode assembly which comprises at least one pair of gas permeable electrodes comprising an anode and a cathode, and an ion conductive electrolyte arranged between each pair of anode and cathode;   an electrode gas space on the non-electrolyte side of each electrode at least one electrode gas space including an inlet and an outlet;   a recirculating loop for recirculating at least a portion of at least one of the produced oxygen or hydrogen product gas from the outlet of the respective electrode gas space to the inlet of the respective electrode gas space;   a water supply vessel in fluid communication with the recirculating loop, the water supply vessel vaporising water from a water supply utilising heat of vaporisation provided by the product gas and introducing said water vapour into the recirculating loop; and   a heat transfer arrangement for transferring heat between the membrane electrode assembly and gas in the gas space located in the electrode gas space fluidly connected to the recirculating loop through the inlet and outlet thereof, wherein the heat transfer arrangement is in contact with the membrane electrode assembly and also allows for gas circulation between the membrane electrode assembly and the respective electrode gas space.   
     
     
         28 . The electrolysis cell system of  claim 27 , wherein the heat transfer arrangement comprises a heat sink in direct physical contact with the respective anode or cathode. 
     
     
         29 . The electrolysis cell system of  claim 28 , wherein the heat sink is in abutting contact or is physically connected to at least one portion of the respective anode or cathode. 
     
     
         30 . The electrolysis cell system of  claim 27 , wherein the heat transfer arrangement comprises at least one of:
 a mesh, preferably a corrugated mesh section;   a perforated sheet; or   a sheet or a plate.   
     
     
         31 . The electrolysis cell system of  claim 27 , wherein the heat transfer arrangement is gas permeable, preferably in a direction parallel to the longitudinal axis of the membrane electrode assembly. 
     
     
         32 . The electrolysis cell system of  claim 27 , wherein the heat transfer arrangement is formed from metal, preferably nickel or stainless steel, more preferably corrosion resistant stainless steel. 
     
     
         33 . The electrolysis cell system of  claim 27 , wherein the electrode gas space including the inlet and the outlet fluidly connected to the recirculating loop is the electrode gas space of the anode and the product gas comprises oxygen. 
     
     
         34 . The electrolysis cell system of  claim 27 , wherein the electrode gas space including the inlet and the outlet fluidly connected to the recirculating loop is the electrode gas space of the cathode and the product gas comprises hydrogen. 
     
     
         35 . The electrolysis cell system of  claim 27 , wherein the water supply vessel comprises a humidifier. 
     
     
         36 . The electrolysis cell system of  claim 35 , wherein the humidifier directly mixes the product gas and water supplied into and flowing through the humidifier. 
     
     
         37 . The electrolysis cell system of  claim 35 , wherein the recirculated oxygen or hydrogen product gas passes through the humidifier and entrains water vapour therein. 
     
     
         38 . The electrolysis cell system of  claim 27 , wherein the heat of vaporisation for water vaporisation is provided by the product gas in the recirculating loop. 
     
     
         39 . The electrolysis cell system of  claim 27 , wherein water is supplied to the water supply vessel at a rate needed to replenish water used in the system by electrolysis. 
     
     
         40 . The electrolysis cell system of  claim 27 , wherein the electrode gas space is housed in an electrode chamber having inlet and outlet openings are located along a gas flow axis which is orientated perpendicular to longitudinal axis of the membrane electrode assembly of the respective electrolysis cell. 
     
     
         41 . The electrolysis cell system of  claim 27 , including at least two electrolysis cells stacked together. 
     
     
         42 . A process of producing hydrogen and oxygen from water using at least one electrolysis cell including a membrane electrode assembly which comprises at least one pair of gas permeable electrodes comprising an anode and a cathode, and an ion conductive electrolyte arranged between each pair of anode and cathode, the or each gas permeable electrodes including an electrode gas space on the non-electrolyte side thereof, at least one of the electrode gas spaces of the anode and cathode including an inlet and an outlet, said process comprising:
 supplying current and water vapour to the membrane electrode assembly to produce hydrogen gas from the cathode and oxygen gas from the anode;   recirculating a portion of at least one of the produced oxygen gas or hydrogen gas from the outlet of the respective electrode gas space through a recirculating loop to the inlet of said respective gas space and through said respective gas space;   vapourising water supplied into the recirculating loop from a water supply utilising energy provided by at least a portion of the respective oxygen or hydrogen product gas in said recirculating loop to provide the requisite heat of vaporisation; and   transferring heat between the membrane electrode assembly and product gas in said respective electrode gas space using a heat transfer arrangement located in said respective electrode gas space which is in contact with the membrane electrode assembly and also allows for gas circulation between the membrane electrode assembly and said respective electrode gas space.   
     
     
         43 . The process of  claim 42 , wherein the step of vapourising water occurs in a humidifier. 
     
     
         44 . The process of  claim 42 , wherein the step of vapourising water includes mixing water into the recirculating a portion of produced oxygen gas thereby transferring heat from the produced oxygen product gas to water in said mixture for water vaporisation. 
     
     
         45 . The process of  claim 42 , wherein said respective gas space is the electrode gas space of the anode and the product gas comprises oxygen. 
     
     
         46 . The process of  claim 42 , wherein said respective gas space is the electrode gas space of the cathode and the product gas comprises hydrogen.