Integration of Molten Carbonate Fuel Cells in Cement Processing
In various aspects, systems and methods are provided for operating molten carbonate fuel cells with processes for cement production. The systems and methods can provide process improvements including increased efficiency, reduction of carbon emissions per ton of product produced, and simplified capture of the carbon emissions as an integrated part of the system. The number of separate processes and the complexity of the overall production system can be reduced while providing flexibility in fuel feed stock and the various chemical, heat, and electrical outputs needed to power the processes.
1 . A method for producing cement, the method comprising:
introducing a fuel stream comprising a reformable fuel into an anode of a molten carbonate fuel cell, into an internal reforming element associated with the anode, or into a combination thereof;
in a process for production of cement, heating a cement kiln to form a cement product and a cement kiln exhaust;
introducing a cathode inlet stream comprising CO 2 and O 2 into a cathode of the fuel cell, the cathode inlet stream comprising at least a portion of the cement kiln exhaust; and
generating electricity within the molten carbonate fuel cell.
2 . The method of claim 1 , further comprising a) transferring heat from at least one of the cement kiln and the cement kiln exhaust to the fuel stream, b) transferring heat to the cement kiln from at least one of: the molten carbonate fuel cell, a fuel cell anode exhaust, and a fuel cell cathode exhaust, or c) both a) and b).
3 . The method of claim 1 , further comprising withdrawing, from a fuel cell anode exhaust, a gas stream comprising H 2 , at least a portion of the withdrawn gas stream being used as a fuel for heating the cement kiln.
4 . The method of claim 1 , wherein the cement product comprises a cement clinker product.
5 . The method of claim 1 , wherein the molten carbonate fuel cell is operated to generate electricity at a thermal ratio from about 0.25 to about 1.0.
6 . The method of claim 5 , the method further comprising transferring heat from the process for production cement to the molten carbonate fuel cell.
7 . The method of claim 1 , further comprising processing at least one mineral input in one or more mixers, grinders, or a combination thereof; and introducing the processed at least one mineral input into the cement kiln for heating to form at least a portion of the cement product and thereby generating at least a portion of the cement exhaust.
8 . The method of claim 7 , wherein generating electricity within the molten carbonate fuel cell further comprises using the generated electricity to operate the one or more mixers, grinders, or a combination thereof associated with the cement production process.
9 . The method of claim 7 , further comprising: separating H 2 O from at least a portion of a fuel cell anode exhaust; and using the separated H 2 O in the one or more mixers, grinders, or a combination thereof associated with the cement production process.
10 . The method of claim 3 , further comprising separating at least one of CO 2 and H 2 O from at least one of the fuel cell anode exhaust and the withdrawn gas stream in one or more separation stages.
11 . The method of claim 1 , wherein an amount of the reformable fuel introduced into the anode, into the internal reforming element associated with the anode, or into the combination thereof, provides a reformable fuel surplus ratio of at least about 1.5.
12 . The method of claim 1 , wherein a ratio of net moles of syngas in a fuel cell anode exhaust to moles of CO 2 in a fuel cell cathode exhaust is at least about 2.0.
13 . The method of claim 1 , wherein a fuel utilization in the anode is about 50% or less and a CO 2 utilization in the cathode is at least about 60%.
14 . The method of claim 1 , wherein the molten carbonate fuel cell is operated to generate electrical power at a current density of at least about 150 mA/cm 2 and at least about 50 mW/cm 2 of waste heat, the method further comprising performing an effective amount of an endothermic reaction to maintain a temperature differential between an inlet of the anode and an outlet of the anode of about 100° C. or less.
15 . The method of claim 14 , wherein performing the endothermic reaction consumes at least about 40% of the waste heat.
16 . The method of claim 1 , wherein an electrical efficiency for the molten carbonate fuel cell is between about 10% and about 40% and a total fuel cell efficiency for the molten carbonate fuel cell is at least about 55%.
17 . The method of claim 1 , wherein at least about 90 vol % of the reformable fuel is methane.