Filler material mixture

• US 20020023537A1
• Filed: 07/26/2001
• Published: 02/28/2002
• Est. Priority Date: 04/26/1999
• Status: Abandoned Application

• Current Assignee: American Electric Power Service Corporation (American Electric Power Company Incorporated)
• Original Assignee: American Electric Power Service Corporation (American Electric Power Company Incorporated)
• Inventors: Hume, John D., Ridgeway, Russel F., Mainieri, John F.
• Application Number:
  US09/915,779
• Publication Number:
  US 20020023537A1
• Time in Patent Office: Days
• US Class Current: 95/69
• CPC Class Codes: B03C 3/88 Cleaning-out collected particles
• CPC Class Codes: C04B 18/027 Lightweight materials
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 18/082 Cenospheres
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete

Abstract

A low density ash particle separation and collection method and device for separating low density particles, primarily frothy-solid particles with internal and external porosity and thick walled hollow particles, from the overall mixture of higher density particles including raw fly ash as produced by coal fired power plants. Specifically, the invention relates to a device and method for separating and collecting the low density fly ash fraction composed of thick walled hollow fly ash particles and frothy generally solid particles with both internal and external porosity and a relatively small amount of cenospheres from the overall mixture of ash particles composing raw ash as produced by coal fired power plants by de-energizing one or more fields of large electrostatic precipitators during electrostatic precipitation of the ash resulting in the dropping out of the lower density particles in the hoppers located below the de-energized field(s) of the electrostatic precipitator.

Claims

1. A method of separating a low density fly ash fraction from an overall group of fly ash entrained in a gas stream comprising the steps of:

passing the gas through a duct having a first area;

passing the gas stream from the duct through an expansion nozzle;

passing the gas stream through the expansion nozzle and into a hollow body having a second area, whereby the second area is larger than the first area;

decelerating the gas stream as it enters the expansion nozzle to separate out low density ash particles; and

collecting the low density ash particles from a hopper positioned adjacent the expansion nozzle.

2. A method as defined in claim 1 in which the second area is in the range of from six to twenty-five times larger than the area of the duct.

3. A method as defined in claim 2 in which the second area is in the range of from nine to fifteen times larger than the first area.

4. The method as defined in claim 1 in which the expansion nozzle is positioned adjacent an electrostatic precipitator.

5. The method as defined in claim 1, comprising the further steps of positioning the duct adjacent an electrostatic precipitator having at least one electrostatic field;

de-energizing at least one electrostatic field in the electrostatic precipitator; and

allowing the low density ash to fall into the hopper positioned adjacent the expansion nozzle.

6. The method as defined in claim 5 in which the de-energized field is the first field positioned adjacent the expansion nozzle in the electrostatic precipitator.

7. The method as defined in claim 5 in which at least the first two fields are de-energized in the electrostatic precipitator.

8. The method as defined in claim 1 in which the electrostatic precipitator has a maximum capacity for a pre-determined gas stream level, and in which the electrostatic precipitator is oversized in capacity with respect to said pre-determined gas stream level flowing thereby.

9. The method as defined in claim 1 in which the electrostatic precipitator collects ash from the overall gas stream having a first ash density, and in which the low density ash collected in the hopper positioned adjacent the expansion nozzle is at least ten (10) percent lower in density than the first ash density produced by the electrostatic precipitator.

10. The method as defined in claim 9 in which the electrostatic precipitator collects ash from the overall gas stream having a first ash density, and in which the low density ash collected in the hopper positioned adjacent the expansion nozzle is at least thirty-five (35) percent lower in density than the first ash density produced by the electrostatic precipitator.

11. The method as defined in claim 9 in which the low density ash that is

collected has a specific gravity of 2.0 or less.

12. The method as defined in claim 11 in which the low density ash collected in the hopper positioned adjacent the expansion nozzle has a specific gravity in the range of from 1.6 to 1.99.

13. The method as defined in claim 1 in which the low density ash that is

collected in the hopper positioned adjacent the expansion nozzle has a particle size distribution that is predominantly in the range of from between 30 microns to 400 microns.

14. The method as defined in claim 13 in which the low density ash that is collected includes a major amount of frothy, semi-solid particles with both internal and external porosity and a minor amount of hollow particles with thick walls containing internal and external pores.

15. The method as defined in claim 1 in which the low density ash that is collected includes a major amount of frothy, semi-solid particles with both internal and external porosity and a minor amount of hollow particles with thick walls containing internal and external pores.

16. The method as defined in claim 15 in which the low density ash further includes a minor amount of cenospheres.

18. The electrostatic precipitator as defined in claim 17 in which the plurality of energizable fields includes a first energizable field nearest the inlet duct that is the field de-energized by the de-energizing mechanism.

19. The electrostatic precipitator as defined in claim 18 in which at least two fields are de-energized by the de-energizing mechanism.

20. The electrostatic precipitator as defined in claim 17 further comprising

a hopper beneath each field for collecting the fallout during the separation of the lower density ash from the overall gas stream.

21. The electrostatic precipitator as defined in claim 17 in which the electrostatic precipitator has a first capacity defined by the maximum stream of overall ash flowing thereby, and in which the electrostatic precipitator is oversized in capacity relative to the first capacity.

22. The electrostatic precipitator as defined in claim 17 in which the overall ash stream has a first density, and in which the low density ash collected is at least ten (10) percent lower in density than the first density of the ash stream.

23. The electrostatic precipitator as defined in claim 18 in which the overall ash stream has a first density, and in which the low density ash collected is at least thirty-five (35) percent lower in density than the first density of the ash stream.

24. The electrostatic precipitator as defined in claim 17 in which the low density ash that is collected has a specific gravity of 2.0 or less.

25. The electrostatic precipitator as defined in claim 24 has a specific gravity in the range of from 1.6 to 1.99.

26. The electrostatic precipitator as defined in claim 17 comprising a low density ash derived from the ash contained in a gas stream generated from the combustion of coal, in which the low density ash consists of a major amount of solid particles having internal and external porosity and a minor amount of hollow particles having internal and external porosity.

27. The electrostatic precipitator as defined in claim 17 in which the low density ash is sized predominantly in the range of from between 30 microns to 400 microns.

29. A lightweight filler material as defined in claim 28 whereby the body has a specific gravity less than 2.0.

30. A lightweight filler material as defined in claim 29 in which the body has a specific gravity in the range of from 1.6 to 1.99.

31. A lightweight filler material as defined in claim 28 in which the body has both internal and external porosity.

32. A lightweight filler material as defined in claim 28 in which the overall ash stream has an average first density, and in which the lightweight filler material has a density of at least ten (10) percent lower than the average first density of the ash stream.

33. A lightweight filler material as defined in claim 28 in which the overall ash stream has an average first density, and in which the lightweight filler material has a density of at least thirty-five (35) percent lower than the average first density of the ash stream.

35. The mixture of filler material as defined in claim 34 in which the overall ash stream has a first density, and in which the low density ash collected is at least ten percent (10) lower in density than the first density of the ash stream.

36. The mixture of filler material as defined in claim 35 in which the overall ash stream has a first density, and in which the low density ash collected is at least thirty-five percent (35) lower in density than the first density of the ash stream.

37. A mixture of filler material collected by precipitation from a gas stream as a result of deceleration of the gas stream as defined in claim 34 in which the low density ash that is collected has a specific gravity of less than 2.0.

38. A mixture of filler material collected by precipitation from a gas stream as a result of deceleration of the gas stream as defined in claim 34 in which the low density ash that is collected has a specific gravity in the range of from 1.6 to 1.99.

39. The mixture as defined in claim 34 comprising a low density coal ash derived from the overall ash contained in a gas stream generated from the combustion of coal in which the major amount of solid particles have internal and external porosity, and in which the minor amount of hollow particles have internal and external porosity.

40. The mixture as defined in claim 34 in which a minor amount of cenospheres are present in the mixture.

41. The mixture as defined in claim 39 in which the mixture contains solid particles in the range of from 10% to 70% of the total mixture by weight;

and hollow particles in the range of from 10% to 70% of the total mixture by weight.

42. The mixture as defined in claim 41 in which the mixture contains solid particles in the range of from 20% to 60% of the total mixture by weight;

hollow particles in the range of from 10% to 50% of the total mixture by weight.

43. The mixture as defined in claim 40 in which the cenospheres are in the range of from 0.01% to 3% by weight in the mixture.

44. The mixture as defined in claim 41 in which the cenospheres are in the range of from 0.75% to 1.5% by weight in the mixture.

17. An electrostatic precipitator for separating low density ash from the overall gas stream generated from the combustion of coal in a power generation facility comprising:

a hollow body having an inlet duct having a first area;

an outlet duct;

whereby the hollow body has a second area and in which the second area is larger than the first area;

a plurality of energizable fields longitudinally positioned next to one another within the hollow body; and

a de-energizing mechanism for de-energizing at least one of the energizable fields resulting in the separation of the lower density ash from the overall gas stream.

28. A lightweight filler material consisting essentially of a body formed primarily of fly ash generated from a coal burning power generation facility, said body having a size predominantly in the range of from 30 microns to 400 microns;

and having a plurality of interstitial cavities formed on and in the body.

34. A mixture of filler material collected by precipitation from a gas stream as a result of the deceleration of the gas stream comprising:

a major amount of solid particles having a size in the range of from 30 to 400 microns; and

a minor amount of hollow particles having a size in the range of from 30 to 400 microns.