Methods and systems for producing syngas
Methods and systems are provided for producing syngas utilizing heat from thermochemical conversion of a carbonaceous fuel to support decomposition of at least one of water and carbon dioxide using one or more solid-oxide electrolysis cells. Simultaneous decomposition of carbon dioxide and water or steam by one or more solid-oxide electrolysis cells may be employed to produce hydrogen and carbon monoxide. A portion of oxygen produced from at least one of water and carbon dioxide using one or more solid-oxide electrolysis cells is fed at a controlled flow rate in a gasifier or combustor to oxidize the carbonaceous fuel to control the carbon dioxide to carbon monoxide ratio produced.
1. A method for forming syngas, comprising:
producing heat and a mixed gas comprising carbon dioxide, carbon monoxide, water and hydrogen by gasifying a carbonaceous fuel;
condensing the mixed gas to remove at least one impurity from the mixed gas and to generate a feed stream;
after the condensing act, transferring the heat produced by gasifying the carbonaceous fuel to the feed stream to convert at least a portion of the water in the feed stream to steam;
introducing the feed stream to at least one solid-oxide electrolysis cell;
electrolyzing carbon dioxide and steam in the feed stream in at least one solid-oxide electrolysis cell to produce carbon monoxide, hydrogen and oxygen; and
separating the carbon monoxide and hydrogen from the oxygen.
2. The method of claim 1 , further comprising transferring heat from the carbon monoxide, hydrogen and oxygen produced in the at least one solid-oxide electrolysis cell to the feed stream.
3. The method of claim 1 , further comprising contacting the mixed gas with a water stream having a temperature substantially lower than a temperature of the mixed gas to cool the mixed gas.
4. The method of claim 1 , wherein producing heat and a mixed gas comprising carbon dioxide, carbon monoxide, water and hydrogen by gasifying a carbonaceous fuel comprises gasifying the carbonaceous fuel in the presence of a portion of the oxygen formed by electrolyzing carbon dioxide and steam to control a ratio of carbon monoxide and hydrogen produced by electrolyzing the carbon dioxide and the steam.