Recirculation complex for increasing yield from fuel cell with CO
A system and method are provided for boosting overall performance of a fuel cell while simultaneously separating a nearly pure stream of CO 2 for sequestration or for use in generating electrical power to further increase overall efficiency of the process. The system and method employ a heat exchanger system configured to generate a stream of fuel that is returned to the inlet of the fuel cell anode with a higher molar concentration of carbon monoxide (CO) and hydrogen (H 2 ) fuel than was initially present in the fuel cell anode outlet.
1. A fuel cell recirculation complex comprising:
a fuel cell comprising an anode configured to generate a hot anode exhaust stream, the anode comprising an inlet and an outlet;
a waste heat recovery cycle configured to generate power from cooling the hot anode exhaust stream;
a compressor configured to compress the exhaust gas cooled via the waste heat recovery cycle;
an expander configured to expand and cool the compressed exhaust gas; and
a heat exchanger system configured to receive at least a portion of the expanded gas and to pre-cool the compressed waste heat recovery cycle exhaust gas prior to cooling via the expander, and further configured to remove by phase change water (H2O) and carbon dioxide (CO2) from the exhaust gas passing through the waste heat recovery cycle, and further configured to generate a stream of fuel that is returned to the inlet of the fuel cell anode with a higher molar concentration of carbon monoxide (CO) and hydrogen (H2) fuel than was initially present in the fuel cell anode exhaust gas prior to entering the waste heat recovery cycle.
2. The fuel cell recirculation complex wherein the fuel cell comprises a solid-oxide fuel cell.
3. The fuel cell recirculation complex wherein the waste heat recovery cycle comprises an Organic Rankine cycle.
4. The fuel cell recirculation complex according to claim 1 , wherein the heat exchanger system and expander together are configured to remove CO2 in solid form condensed from the expanded gas generated via the expander, in liquid form condensed from the stream of fuel generated via the heat exchanger system prior to returning the stream of fuel to the inlet of the fuel cell, or both.
5. The fuel cell recirculation complex according to claim 1 , further comprising an electrically powered cooling unit configured to further cool the compressed waste heat recovery cycle exhaust gas passing through the heat exchanger system.
6. The fuel cell recirculation complex according to claim 5 , wherein the electrically powered cooling unit and heat exchanger system are together configured to remove CO2 in solid form condensed from the stream of fuel generated via the heat exchanger system prior to returning the stream of fuel to the inlet of the fuel cell, in liquid form condensed from the stream of fuel generated via the heat exchanger system prior to returning the stream of fuel to the inlet of the fuel cell, or both.
7. The fuel cell recirculation complex according to claim 1 , wherein the fuel cell, waste heat recovery cycle, compressor, expander and heat exchanger system together provide a fuel cell operating at greater than about 50% efficiency.
8. The fuel cell recirculation complex according to claim 1 , wherein the fuel cell further comprises a cathode configured to generate supplemental heat driving the waste heat recovery cycle such that the power generated via the waste heat recovery cycle is greater than the power generated via the waste heat recovery cycle in response to solely cooling the hot anode.