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

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 having a temperature of about 50° C. to about 150° C. 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 stream having a temperature of about 250° C. to about 350° C.;
• splitting the steam feed stream to 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 syngas 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 having a temperature of about 550° C. to about 650° C.;
• heating the first steam feed stream in a third heat exchanger using a second heated syngas effluent from the cathode of the electrolyzer as a heat transfer medium to generate a first heated steam effluent having a temperature of about 550° C. to about 650° C.;
• 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 having a temperature of about 550° C. to about 650° C.;
• combusting, in a combustion unit, the second tail gas stream to transfer heat from the combusting to heat the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent and generate a heated carbon dioxide and steam stream effluent having a temperature of about 700° C. to about 950° C.;
• and
• passing the heated carbon dioxide and steam stream effluent to the cathode of the electrolyzer.

A system, comprising:

• a first heat exchanger configured to heat a carbon dioxide feed stream 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 having a temperature of about 550° C. to about 650° C.;
• a second heat exchanger configured to heat a first steam feed stream having a temperature of about 250° C. to about 350° C. using a second cathode effluent from the cathode of the electrolyzer as a heat transfer medium to generate a first heated steam effluent having a temperature of about 550° C. to about 650° C.;
• a third heat exchanger configured to heat a second steam feed stream having a temperature of about 250° C. to about 350° C. using an anode effluent from the anode of the electrolyzer as a heat transfer medium to generate a second heated steam effluent having a temperature of about 550° C. to about 650° C.;
• and
• a combustion unit configured to combust a tail gas feed stream to transfer heat from the combusting to the heated carbon dioxide effluent, the first heated steam effluent and the second heated steam effluent to generate a heated carbon dioxide and steam stream effluent having a temperature of about 700° C. to about 950° C. for sending to the cathode of the electrolyzer.