Sorbent composition for use in a flue gas train including a baghouse
A sorbent composition for enhanced baghouse function is described. The composition may include a sorbent such as powder activated carbon as well as an additive that is a heat moderator or a permeability agent. The heat moderator may act as a heat sink or barrier. Heat moderators may include in non-limiting examples phyllosilicates, cyclosilicates, or nesosilicates that may include, montmorillonite, bentonite, halloysite, aluminum silicates, muscovite, illite, kaolin, andalusite, kyanite, sillimanite, metakaolin, mullite, polymers, such as chitosan, and/or clays, either natural or synthetic (e.g., montmorillonite), or polyethylenimine. Permeability may be affected by mixing sorbents of lower D50 with sorbents of higher D50 in various ratios, or addition of a permeability agent such as a phyllosilicate, perlite, silica, diatomaceous earth. Further, a permeability agent such as a fluoropolymer may be coated onto or admixed with the sorbent. Diatomaceous earth, perlites, or silicates may also increase permeability. The compositions are particularly useful in flue gas treatment systems with baghouse separation units in that they have reduced combustibility and increased permeability properties.
1. A sorbent composition that enhances baghouse unit performance, the sorbent composition comprising:
a first particulate sorbent comprising powdered activated carbon and having a median particle diameter of not greater than about 30 μm and at least about 20 μm; and
a second particulate sorbent comprising powdered activated carbon and having a median particle diameter of not greater than about 20 μm and at least about 8 μm, wherein the median particle diameter of the second particulate sorbent is at least about 5 μm less than the median particle diameter of the first particulate sorbent,
wherein a pressure drop as measured in a permeability test under an applied normal stress of 15 kPa at an air velocity of 0.5 mm/s is not greater than about 78 mBar.
2. The composition of claim 1 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is not greater than about 5:1.
3. The composition of claim 1 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is not greater than about 4:1.
4. The composition of claim 1 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is at least about 1:6.
5. The composition of claim 1 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is at least about 1:1
6. The composition of claim 1 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is at least about 2:1.
7. The composition of claim 1 , further comprising an oxidizing agent.
8. The composition of claim 7 , wherein the oxidizing agent comprises an inorganic halogen salt.
9. The composition of claim 1 , further comprising a flow aid selected from the group consisting of graphite, talc, mica and combinations thereof.
10. The composition of claim 1 , wherein the sorbent composition comprises not more than about 10 wt. % of sorbent particles having a size of less than 5 μm based on a total sorbent composition.
11. The composition of claim 1 , further comprising a permeability additive selected from the group consisting of perlite, silica, diatomaceous earth, zeolites, and combinations thereof
12. A sorbent composition that enhances baghouse unit performance comprising a particulate sorbent having a median particle diameter (D50) of not greater than about 30 μm, and a permeability additive comprising perlite, wherein a pressure drop as measured in a permeability test under an applied normal stress of 15 kPa at an air velocity of 0.5 mm/s is not greater than about 78 mBar.
13. The composition of claim 12 , wherein the pressure drop as measured in a permeability test under an applied normal stress of 15 kPa at an air velocity of 0.5 mm/s is not greater than about 65 mBar.
14. The composition of claim 12 , wherein the pressure drop as measured in a permeability test under an applied normal stress of 15 kPa at an air velocity of 0.5 mm/s is not greater than about 50 mBar.
15. The composition of claim 12 , wherein the composition comprises at least about 0.5 wt.% of the permeability additive.
16. The composition of claim 12 , wherein the composition comprises not greater than about 10 wt.% of the permeability additive.
17. The composition of claim 12 , further comprising an oxidizing agent.
18. The composition of claim 17 , wherein the oxidizing agent comprises an inorganic halogen salt.
19. The composition of claim 12 , wherein the particulate sorbent comprises powdered activated carbon.
20. A sorbent composition that enhances baghouse unit performance, the sorbent composition comprising:
a first particulate sorbent comprising powdered activated carbon and having a median particle diameter of not greater than about 30 μm and at least about 20 μm; and
a second particulate sorbent comprising powdered activated carbon and having a median particle diameter of not greater than about 20 μm and at least about 8 μm, wherein the median particle diameter of the second particulate sorbent is at least about 5 μm less than the median particle diameter of the first particulate sorbent.
21. The composition of claim 20 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is not greater than about 5:1.
22. The composition of claim 20 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is not greater than about 4:1.
23. The composition of claim 20 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is at least about 1:6.
24. The composition of claim 20 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is at least about 1:1
25. The composition of claim 20 , wherein a weight ratio of the first particulate sorbent to the second particulate sorbent is at least about 2:1.
26. The composition of claim 20 , further comprising an oxidizing agent.
27. The composition of claim 26 , wherein the oxidizing agent comprises an inorganic halogen salt.
28. The composition of claim 20 , further comprising a flow aid selected from the group consisting of graphite, talc, mica and combinations thereof.
29. The composition of claim 20 , wherein the sorbent composition comprises not more than about 10 wt. % of sorbent particles having a size of less than 5 μm based on a total sorbent composition.
30. The composition of claim 20 , further comprising a permeability additive selected from the group consisting of perlite, silica, diatomaceous earth, zeolites, and combinations thereof.