Solid oxide electrochemical gas separator inerting system

Abstract

An air inert gas generating system consists of heat exchangers, a heating element, and a plurality of solid oxide electrochemical gas separator (SOEGS) cells. The SOEGS cells are interconnected in series to create a stack. A voltage is applied to the stack causing oxygen ions to be transported from the air flowing through the cathode through the electrolyte to the anode side of the SOEGS, resulting in oxygen-depleted gas. The oxygen-depleted gas can be used to inert the ullage of aircraft fuel tank or support the fire suppression system in the cargo hold. The oxygen-enriched gas can be used for other purposes.

1 . An electrochemical gas separation system comprising:
 an inlet configured to port incoming process air;   a plurality of solid oxide electrochemical gas separator cells, each comprising:
 a cathode configured for receiving heated process air; 
 an anode configured for receiving oxygen ions; 
 an electrolyte comprising an oxygen ion conductor, the electrolyte configured to transport oxygen ions reduced from the process air at the cathode when a bias voltage is applied from the anode to the cathode; 
   a plurality of interconnectors, wherein each of the interconnectors is configured to electrically link each of the plurality of solid oxide electrochemical gas separator cells in series;   a plurality of end portions, wherein each end portion is adjacent to one of the plurality of cells;   a power source configured to apply a bias voltage across the plurality of solid oxide electrochemical gas separator cells; and   an outlet configured to release oxygen-depleted air.   
     
     
         2 . The electrochemical gas separation system of  claim 1 , further comprising:
 a cathode heat recovery heat exchanger that comprises:
 a cold side configured to receive and heat process air; and 
 a hot side configured to receive and cool oxygen-depleted air from the plurality of solid oxide electrochemical gas separator cells; and 
   an anode heat recovery heat exchanger that comprises:
 a cold side configured to receive and heat process air from the cathode heat recovery heat exchanger; and 
 a hot side configured to receive and cool oxygen-enriched air. 
   
     
     
         3 . The electrochemical gas separation system of  claim 1 , wherein the incoming process air is selected from the group consisting of engine bleed air, compressed air, ram air, cabin air, and fan air. 
     
     
         4 . The electrochemical gas separation system of  claim 1 , wherein the cathode and the anode materials are selected from the group consisting of ceramic materials or noble metals supported on ceramic substrates. 
     
     
         5 . The electrochemical gas separation system of  claim 1 , wherein the plurality of solid oxide electrochemical gas separator cells are each planar in shape, and are arranged in one or more crossflow stacks which are interconnected. 
     
     
         6 . The electrochemical gas separation system of  claim 1 , wherein the plurality of solid oxide electrochemical gas separator cells are each tubular in shape, and are arranged in one or more stacks which are interconnected. 
     
     
         7 . The electrochemical gas separation system of  claim 1 , further comprising a heating element, wherein the heating element may consist of electrical heaters configured to heat process air or a burner configured to receive and heat oxygen-enriched air from the plurality of solid oxide electrochemical gas separator cells through the burning of fuel. 
     
     
         8 . The electrochemical gas separation system of  claim 1 , further comprising an element configured to pressurize process air, wherein the element consists of a motor-assisted turbocharger or a compressor. 
     
     
         9 . A method for inerting air, the method comprising:
 temperature-conditioning incoming process air;   flowing the process air through a plurality of solid oxide electrochemical gas separator cells, each having a cathode configured for receiving the process air, an anode configured for receiving oxygen ions, and an electrolyte comprising an oxygen ion conductor, the electrolyte configured to reduce oxygen from the process air when a bias voltage is applied from the anode to the cathode;   selectively routing resulting oxygen-enriched air out of the plurality of solid oxide electrochemical gas separator cells;   temperature-conditioning the oxygen-enriched air;   routing the oxygen-enriched air to an outlet;   selectively routing resulting oxygen-depleted air out of the plurality of solid oxide electrochemical gas separator cells;   temperature-conditioning outgoing oxygen-depleted air; and   flowing the temperature-conditioned oxygen-depleted air to a second location.   
     
     
         10 . The method of  claim 9 , further comprising:
 routing incoming process air into a first side of a cathode heat recovery heat exchanger, wherein the first side is configured to heat the process air;   selectively routing the heated process air from the first side of the cathode heat recovery heat exchanger to a first side of an anode heat recovery heat exchanger, where the first side is configured to heat the air;   flowing the heated process air from the first side of the anode heat recovery heat exchanger through the plurality of solid oxide electrochemical gas separator cells,   selectively routing resulting oxygen-depleted air from the plurality of solid oxide electrochemical gas separator cells through a second side of the cathode heat recovery heat exchanger, wherein the second side is configured to cool the air;   flowing the cooled oxygen-depleted air out of the second side of the cathode heat recovery heat exchanger to a second location;   selectively routing resulting oxygen-enriched air to a second side of the anode heat recovery heat exchanger, wherein the second side is configured to cool the air; and   flowing the cooled oxygen-enriched air from the second side of the anode heat recovery heat exchanger to an outlet.   
     
     
         11 . The method of  claim 9 , wherein the process air is heated to at least 500 degrees Celsius and no more than 1100 degrees Celsius while exiting the cathode heat recovery heat exchanger. 
     
     
         12 . The method of  claim 9 , further comprising routing the heated process air through a bypass valve downstream of the first side of the cathode heat recovery heat exchanger, wherein the bypass valve is configured to allow heated process air to flow into the first side of the anode heat recovery heat exchanger, or alternatively to flow directly to the plurality of solid oxide electrochemical gas separator cells. 
     
     
         13 . The method of  claim 9 , further comprising flowing the heated process air through at least one electrical heater upstream of the plurality of solid oxide electrochemical gas separator cells. 
     
     
         14 . The method of  claim 9 , further comprising flowing the heated process air through at least one flow control valve upstream of the plurality of solid oxide electrochemical gas separator cells. 
     
     
         15 . The method of  claim 9 , further comprising:
 reducing oxygen molecules in the heated process air entering the cathode of the plurality of solid oxide electrochemical gas separator cells;   conducting resulting oxygen ions across the electrolyte to the anode;   recombining the oxygen ions into oxygen molecules in the anode; and   expelling the oxygen molecules from the anode in the resulting oxygen-enriched air stream.   
     
     
         16 . The method of  claim 9 , further comprising:
 routing the oxygen-enriched air from the anode of the plurality of solid oxide electrochemical gas separator cells to a burner configured to heat the oxygen-enriched air through the combustion of fuel.   
     
     
         17 . The method of  claim 9 , wherein the oxygen-depleted air being routed to the second location is cooled to 80 degrees Celsius or lower. 
     
     
         18 . The method of  claim 9 , wherein the second location is the ullage of a fuel tank. 
     
     
         19 . The method of  claim 9 , wherein the second location is a fire suppression system.