Methods and systems for the electrochemical conversion of carbon dioxide and steam to syngas

Abstract

A method includes heating a carbon dioxide feed stream in a first heat exchanger using a first cathode effluent from a cathode of an electrolyzer as a heat transfer medium to generate a heated carbon dioxide effluent, heating a first steam feed stream in a second heat exchanger using a second cathode effluent from the cathode of the electrolyzer as a heat transfer medium to generate a first heated steam effluent, heating a second steam feed stream in a third heat exchanger using an anode effluent from an anode of the electrolyzer as a heat transfer medium to generate a second heated steam effluent, and converting the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer.

1 . A method, comprising:
 heating a carbon dioxide feed stream in a first heat exchanger using a first cathode effluent from a cathode of an electrolyzer comprising an anode, a cathode, and an electrolyte inserted between the anode and the cathode as a heat transfer medium to generate a heated carbon dioxide effluent;   heating a first steam feed stream in a second heat exchanger using a second cathode effluent from the cathode of the electrolyzer as a heat transfer medium to generate a first heated steam effluent;   heating a second steam feed stream in a third heat exchanger using an anode effluent from the anode of the electrolyzer as a heat transfer medium to generate a second heated steam effluent; and   converting the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer.   
     
     
         2 . The method according to  claim 1 , wherein converting the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer comprises heating the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent by an electricity source. 
     
     
         3 . The method according to  claim 1 , wherein converting the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer comprises:
 sending the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to the cathode of the electrolyzer; and   providing electricity to heat the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to generate the heated carbon dioxide and steam stream effluent.   
     
     
         4 . The method according to  claim 1 , wherein converting the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer comprises:
 sending the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heat source to generate the heated carbon dioxide and steam stream effluent having a temperature of about 700° C. to about 950° C.; and   sending the heated carbon dioxide and steam stream effluent to the cathode of the electrolyzer.   
     
     
         5 . The method according to  claim 4 , wherein the heat source comprises a resistive or inductive heating element. 
     
     
         6 . The method according to  claim 4 , wherein the heat source comprises a heat exchanger configured to heat the heated carbon dioxide effluent, first heated steam effluent and the second heated steam effluent using heat extracted from a high-temperature fluid. 
     
     
         7 . The method according to  claim 1 , wherein heating the first steam feed stream further comprises generating a first cooled cathode effluent and heating the carbon dioxide feed stream further comprises generating a second cooled cathode effluent. 
     
     
         8 . The method according to  claim 7 , further comprising:
 heating a water feed stream in a fourth heat exchanger using a reactor synthesis effluent including tail gas from a reactor unit as a heat transfer medium to generate a heated water effluent;   introducing the heated water effluent, the first cooled cathode effluent, the second cooled cathode effluent and a tail gas stream to the reactor unit;   performing an exothermic reaction in the reactor unit, thereby transferring heat from the exothermic reaction to the heated water effluent to vaporize the heated water effluent and generate a third steam feed stream; and   splitting the third steam feed stream into the first steam feed stream and the second steam feed stream.   
     
     
         9 . The method according to  claim 8 , wherein the first cooled cathode effluent and the second cooled cathode effluent are combined into a third cooled cathode effluent, and the method further comprises passing the third cooled cathode effluent to the reactor unit, wherein the first cooled cathode effluent and the second cooled cathode effluent are each a first cooled syngas effluent and a second cooled syngas effluent. 
     
     
         10 . The method according to  claim 9 , wherein the exothermic reaction in the reactor unit produces a chemical product or a fuel. 
     
     
         11 . The method according to  claim 10 , wherein the chemical product is one or more of methanol and dimethyl ether and the fuel is one or more of gasoline, diesel, and jet fuel. 
     
     
         12 . The method according to  claim 9 , wherein the exothermic reaction in the reactor unit produces a Fischer-Tropsch product. 
     
     
         13 . The method according to  claim 9 , wherein the exothermic reaction in the reactor unit comprises converting the first cooled syngas effluent, the second cooled syngas effluent and the tail gas stream to the reactor synthesis effluent including tail gas, and the method further comprises:
 splitting the reactor synthesis effluent into a first reactor synthesis effluent and a second reactor synthesis effluent;   heating the water feed stream in the fourth heat exchanger using the first reactor synthesis effluent as a heat transfer medium to generate the heated water effluent and a cooled first reactor synthesis effluent;   cooling the second reactor synthesis effluent in a fifth heat exchanger to generate a cooled second reactor synthesis effluent;   combining the cooled first reactor synthesis effluent and the cooled second reactor synthesis effluent to form a third cooled reactor synthesis effluent;   separating the tail gas from the third cooled reactor synthesis effluent into a first tail gas stream and a second tail gas stream; and   passing the first tail gas stream to the combustion unit for combustion.   
     
     
         14 . The method according to  claim 1 , further comprising:
 heating an anode purge stream in a fourth heat exchanger using the anode effluent from the anode of the electrolyzer as a heat transfer medium to generate a heated anode purge stream for sending to the anode of the electrolyzer.   
     
     
         15 . The method according to  claim 1 , wherein the electrolyzer is a solid oxide electrolyzer. 
     
     
         16 . A method, comprising:
 heating a water feed stream in a first heat exchanger using a reactor synthesis effluent including tail gas from a reactor unit as a heat transfer medium to generate a heated water effluent and a cooled reactor synthesis effluent including the tail gas;   separating the tail gas from the cooled reactor synthesis effluent to generate a first tail gas stream and a second tail gas stream;   introducing the first tail gas stream, a cooled cathode effluent and the heated water effluent to the reactor unit;   performing an exothermic reaction comprising the first tail gas stream and the cooled cathode effluent in the reactor unit thereby transferring heat from the exothermic reaction to the heated water effluent to generate a steam feed;   splitting the steam feed stream into a first steam feed stream and a second steam feed stream;   heating a carbon dioxide feed stream in a second heat exchanger using a first heated cathode effluent from a cathode of an electrolyzer comprising an anode, a cathode, and an electrolyte inserted between the anode and the cathode as a heat transfer medium to generate a heated carbon dioxide effluent;   heating the first steam feed stream in a third heat exchanger using a second heated cathode effluent from the cathode of the electrolyzer as a heat transfer medium to generate a first heated steam effluent;   heating the second steam feed stream in a fourth heat exchanger using an anode effluent from the anode of the electrolyzer as a heat transfer medium to generate a second heated steam effluent; and   converting the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer.   
     
     
         17 . The method according to  claim 16 , wherein converting the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer comprises:
 sending the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to the cathode of the electrolyzer; and   providing electricity to heat the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to generate the heated carbon dioxide and steam stream effluent.   
     
     
         18 . The method according to  claim 16 , wherein converting the heated carbon dioxide effluent, the first heated steam effluent and the second steam feed to a heated carbon dioxide and steam stream effluent having a temperature for use in the cathode of the electrolyzer comprises:
 sending the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to a heat source to generate the heated carbon dioxide and steam stream effluent; and   sending the heated carbon dioxide and steam stream effluent to the cathode of the electrolyzer.   
     
     
         19 . A system, comprising:
 a reactor unit configured to perform an exothermic reaction with a tail gas stream and a cooled cathode effluent thereby transferring heat from the exothermic reaction to a heated water effluent to generate a steam feed stream;   a first heat exchanger configured to heat a carbon dioxide feed stream using a first heated cathode effluent from a cathode of an electrolyzer comprising an anode, a cathode, and an electrolyte inserted between the anode and the cathode as a heat transfer medium to generate a heated carbon dioxide effluent;   a second heat exchanger configured to heat a first one of the steam feed stream using a second heated cathode effluent from the cathode of the electrolyzer as a heat transfer medium to generate a first heated steam effluent;   a third heat exchanger configured to heat a second one of the steam feed stream using a heated anode effluent from the anode of the electrolyzer as a heat transfer medium to generate a second heated steam effluent; and   a heat source configured to generate a heated carbon dioxide and steam stream effluent from the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent for use in the cathode of the electrolyzer.   
     
     
         20 . The system according to  claim 19 , wherein the heat source is one of an electricity source for providing electricity to heat the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to generate the heated carbon dioxide and steam stream effluent, a resistive or inductive heating element to heat the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent prior to sending the heated carbon dioxide and steam stream effluent to the cathode of the electrolyzer or a heat exchanger configured to heat the heated carbon dioxide effluent, first heated steam effluent and the second heated steam effluent using heat extracted from a high-temperature fluid prior to sending the heated carbon dioxide and steam stream effluent to the cathode of the electrolyzer.