Method for combustion of multiple fuels
According to embodiments, a co-fired or multiple fuel combustion system is configured to apply an electric field to a combustion region corresponding to a second fuel that normally suffers from poor combustion and/or high sooting. Application of an AC voltage to the combustion region was found to increase the extent of combustion and significantly reduce soot evolved from the second fuel.
1. A method for operating a combustion system, comprising:
outputting a first fuel and a first oxidant;
supporting a first combustion reaction with the first fuel and first oxidant;
supporting a second combustion reaction of a heated second fuel to produce a flue gas including entrained particles;
providing an electrical charge to the second combustion reaction, wherein the electrical charge is carried by the entrained particles;
supporting a first field electrode adjacent to a main flow of the flue gas;
applying a first voltage to the first field electrode; and
electrostatically attracting the entrained particles toward the first field electrode to remove at least a portion of the entrained particles from a main flow of the flue gas.
2. The method of claim 1 , wherein the first voltage is opposite in polarity to the electrical charge provided to the second combustion reaction.
3. The method of claim 1 , wherein providing the electrical charge to the second combustion reaction includes applying a voltage to a grate supporting the second fuel and transferring charges from the grate to the second fuel.
4. The method of claim 3 , wherein the grate comprises a crucible.
5. The method of claim 1 , wherein providing the electrical charge to the second combustion reaction includes operating an ionizer to apply charges to the first combustion reaction.
6. The method of claim 1 , further comprising: outputting a second oxidant proximal to the second fuel.
7. The method of claim 6 , wherein providing the electrical charge to the second combustion reaction includes operating an ionizer to apply charges to the second oxidant.
8. The method of claim 1 , further comprising:
providing a second field electrode disposed in juxtaposition to the first field electrode; and
applying a second voltage different than the first voltage to the second field electrode to form an electric field between the first and second field electrodes.
9. The method of claim 8 , wherein the first field electrode comprises a plurality of conductors disposed across the main flow of the flue gas; and wherein the second field electrode comprises a plurality of conductors interlineated with the first electrode plurality of conductors.
10. The method of claim 8 , wherein the second voltage is opposite in polarity to the first voltage.
11. The method of claim 1 , further comprising:
providing a secondary flue gas flow different than the main flow of the flue gas adjacent to the first field electrode; and
entraining the electrostatically attracted particles in the secondary flue gas flow.
12. The method of claim 11 , further comprising: directing the secondary flue gas flow and entrained electrostatically attracted particles toward the first or second combustion reaction.
13. The method of claim 11 , further comprising removing the entrained electrostatically attracted particles from the secondary flue gas flow by filtering the secondary flue gas flow.