Sorbents for coal combustion
Sorbent compositions containing iodine are added to coal to mitigate the release of mercury and/or other harmful elements into the environment during combustion of coal containing natural levels of mercury.
1. A method for reducing environmental emissions of mercury arising from combusting a mercury containing fuel in a furnace of a facility, wherein the facility comprises a convective pathway for combustion gases from the furnace, the method comprising:
applying a sorbent composition comprising iodine and calcium onto the fuel;
delivering the fuel into the furnace;
combusting the fuel together with the applied sorbent composition to produce heat energy and combustion gases; and
measuring the level of mercury in the combustion gases.
2. The method of claim 1 , wherein the sorbent composition comprises calcium iodide.
3. The method of claim 1 , wherein the sorbent composition comprises an iodide, an iodate, or a hypoiodite.
4. The method of claim 1 , comprising applying 0.01-10% by weight of the sorbent composition, based on the weight of the fuel being burned.
5. The method of claim 1 , wherein the sorbent composition further comprises silica and alumina.
6. The method of claim 5 , wherein the sorbent composition comprises an aluminosilicate clay.
7. The method of claim 6 , wherein the clay comprises kaolin.
8. The method of claim 6 , wherein the clay comprises montmorillonite.
9. The method of claim 1 , wherein the facility comprises a chemical scrubber disposed in the convective pathway.
10. The method of claim 9 , wherein the chemical scrubber is a wet scrubber or an SCR control system.
11. The method of claim 1 , wherein the facility comprises a particulate removal system disposed in the convective pathway.
12. The method according to claim 11 , wherein the particulate removal system is an electrostatic precipitator.
13. The method according to claim 11 , wherein the particulate removal system is a bag house.
14. The method of claim 1 , further comprising applying a mercury sorbent composition comprising a halogen into the combustion gases where the temperature is between 1500° F. and 2700° F.
15. The method of claim 14 , wherein the mercury sorbent composition comprises an organic bromine compound.
16. The method of claim 14 , wherein the mercury sorbent composition comprises a bromide salt, a bromate salt, or a hypobromite salt.
17. The method of claim 14 , wherein the mercury sorbent composition comprises an iodide salt, and iodate salt, or a hypoiodite salt.
18. The method of claim 1 , wherein the fuel is coal.
19. A method of reducing emissions of mercury to a desired level, the emissions arising from combustion of mercury containing coal in the furnace of a facility comprising a convective pathway for combustion gases, the method comprising:
adding a sorbent composition onto the coal at an initial treat level;
combusting the coal in the furnace to create heat energy and combustion gases;
measuring the level of mercury in the combustion gases; and
adjusting the treat level up or down as required to meet the desired emissions level;
wherein the sorbent composition comprises calcium iodide.
20. The method of claim 19 , wherein the initial treat level is in the range of 0.01-10% by weight of the coal being combusted.