Method of enhancing the quality of high-moisture materials using system heat sources

• US 8,579,999 B2
• Filed: 04/15/2005
• Issued: 11/12/2013
• Est. Priority Date: 10/12/2004
• Status: Expired due to Fees

• Current Assignee: Rainbow Energy Center LLC
• Original Assignee: Great River Energy
• Inventors: Bullinger, Charles W., Ness, Mark A., Sarunac, Nenad, Levy, Edward K., Weinstein, Richard S., James, Dennis R.
• Primary Examiner(s): Goloboy, James
• Assistant Examiner(s): HINES, LATOSHA D
• Application Number:
  US11/107,152
• Publication Number:
  US 20060075682A1
• Time in Patent Office: 3,133 Days
• Field of Search: 446/26, 445/01, 445/05, 446/29
• US Class Current: 44/626
• CPC Class Codes: C10L 9/08 by heat treatments, e.g. calcining
• CPC Class Codes: F23K 1/04 Heating fuel prior to delivery to combustion apparatus
• CPC Class Codes: F23K 2900/01041 Heating by using exhaust gas heat
• CPC Class Codes: F23L 15/04 Arrangements of recuperators
• CPC Class Codes: F26B 23/001 using waste heat
• CPC Class Codes: F26B 3/084 with heat exchange taking place in the fluidised bed , e.g. combined direct and indirect heat exchange
• CPC Class Codes: Y02E 20/34 Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

The present invention harvests and utilizes fluidized bed drying technology and waste heat streams augmented by other available heat sources to dry feedstock or fuel. This method is useful in many industries, including coal-fired power plants. Coal is dried using the present invention before it goes to coal pulverizers and on to the furnace/boiler arrangement. Coal can be intercepted on current coal feed systems ahead of the pulverizers. Drying fuel, such as coal, is done to improve boiler efficiency and reduce emissions. A two-stage bed utilized in the process first “pre-dries and separates” the feed stream into desirable and undesirable feedstock. Then, it incrementally dries and segregates fluidizable and non-fluidizable material from the product stream. This is all completed in a low-temperature, open-air system. Elevation of fan room air temperature is also accomplished using waste heat, thereby making available to the plant system higher temperature media to enhance the feedstock drying process.

Claims

1. A method for improving a quality characteristic of a material through the application of at least two different waste heat sources, such material being for use within an industrial process operation, wherein such method comprises:

(a) providing a dryer bed for receiving the material and heat content from at least two different waste heat sources to be directed through the material;

(b) providing independent heat exchanger means each operatively connected to a waste heat source, a mixer box and the dryer bed to transfer a desired amount of heat content from each waste heat source to the mixer for use in the dryer bed; and

(c) actively combining heat content contained within the at least two waste heat sources in the mixer box for delivering an aggregate heat content at or below 300°

F. to the dryer bed;

(d) wherein “

waste heat source”

means a gaseous or liquid stream having an elevated heat content resulting from an operation of a process or piece of equipment separate from the heat treatment apparatus, such gaseous or liquid stream being used for the secondary purpose of providing heat content to the heat exchanger instead of being discarded.

2. The method according to claim 1, wherein the material comprises coal.

3. The method of claim 2, wherein the coal comprises subbituminous or lignite coal.

4. The method according to claim 1, wherein the industrial process operation comprises an electric power plant.

5. The method according to claim 1, wherein the industrial process operation comprises a coal coking plant.

6. The method according to claim 1, wherein the improvement to the quality characteristic comprises a reduction in moisture of the material.

7. The method of claim 6, wherein the material is lignite coal whose moisture level is reduced to a value of 15-30% wt.

8. The method of claim 7, wherein the material is lignite coal whose moisture level is reduced to a value of 29-30% wt.

9. The method of claim 6, wherein the material is subbituminous coal whose moisture level is reduced to 15-28 wt %.

10. The method of claim 9, wherein the material is subbituminous coal whose moisture level is reduced to a value of 20-28% wt.

11. The method of claim 1, wherein the dryer bed comprises a fixed-bed dryer.

12. The method of claim 1, wherein, the dryer bed comprises a fluidized-bed dryer containing a bed of the material, and including means for delivering a forced air stream through the fluidized bed to fluidize the material.

13. The method of claim 1 further comprising a heat exchanger operatively connected to the flow of forced air stream for receiving heat from at least one waste heat source for heating the forced air stream prior to its delivery to the fluidized-bed dryer.

14. The method of claim 12, wherein the fluidized-bed dryer comprises a single vessel.

15. The method of claim 12, wherein the fluidized-bed dryer comprises multiple vessels.

16. The method of claim 12, wherein the vessel of the fluidized-bed dryer comprises multiple stages.

17. The method of claim 1, wherein the waste heat source is selected from the group consisting of hot condenser cooling water, hot stack gas, hot flue gas, spent process steam, and discarded heat from operating equipment.

18. The method of claim 1, wherein the temperature delivered to the dryer bed by the heat sources does not exceed 300°

F.

19. The method of claim 18, wherein the temperature delivered to the dryer bed by the heat sources does not exceed 200°

F.

20. The method of claim 1, wherein the particulate material is treated in the dryer bed in the presence of atmospheric air.

21. The method of claim 1, wherein the particulate material is treated in the dryer bed in the absence of an inert gas.

22. The method of claim 1, wherein the particulate material is treated in the dryer bed without the delivery of steam to the dryer bed.

23. The method according to claim 1, wherein the improvement to the quality characteristic comprises a reduction of amount of at least one contaminant contained in the material.

24. The method according to claim 1, wherein the particulate material comprises biomass, bark, peat, forestry waste matter, bauxite or other ores, grains, cereals, malt, cocoa, or a substrate to be modified or transformed within the industrial process operation.

25. The method according to claim 1 further comprising a mixing box operatively connected to the dryer bed, wherein the associated sets of heat exchanger and thermal carrier means for each of the heat sources are operatively connected to the mixing box for communicating a predetermined amount of heat content contained within the at least two heat sources via the thermal carrier means to the mixing box for further communication as a blended amount of heat to the dryer bed.

26. A method for improving a quality characteristic of a particulate material in the form of drying the particulate material through the application of two different waste heat sources, such particulate material being for use within an industrial plant operation, wherein such method comprises:

(a) providing a fluidized-bed dryer unit having an interior for receiving the particulate material;

(b) providing a fluidizing stream for fluidizing the particulate material contained within the dryer unit;

(c) providing a first heat exchanger for transferring heat content from a first waste heat source to the fluidizing stream to increase its temperature before it flows to and through the dryer unit; and

(d) providing a second heat exchanger for transferring heat content from a second waste heat source, different from the first waste heat source, to a third heat exchanger embedded within the dryer unit for increasing the interior temperature of the dryer unit to a temperature at or below 300°

F. such that moisture within the particulate material is reduced.

27. The method of claim 26, wherein the heat source consists of hot condenser cooling water.

28. The method of claim 26 further comprising second waste heat source different in type from the first waste heat source, wherein a combination of the heat contained within the two waste heat sources is delivered via associated heat exchangers to the first heat exchanger operatively associated with the fluidizing stream, or the second heat exchanger operatively associated with the third heat exchanger embedded within the dryer unit.

29. A method for improving a quality characteristic of a particulate feed material in the form of reducing the moisture in the particulate feed material for use in an industrial plant operation producing two different types of waste heat sources and having the particulate feed material delivered to a boiler furnace, such method comprising:

(a) providing a first heat exchanger operatively connected to a hot condenser cooling water waste heat source for transferring heat content from the hot condenser cooling water waste heat source via the first heat exchanger to a fluidizing stream to increase the temperature of the fluidizing stream;

(b) providing a second heat exchanger operatively connected to a flue gas waste heat stream from the boiler furnace for transferring heat content from the flue gas waste heat source via the second heat exchanger to the fluidizing stream that exited the first heat exchanger to further increase the temperature of the fluidizing stream; and

(c) delivering the fluidizing stream heated in series via the first heat exchanger and second heat exchanger to a fluidized bed dryer to fluidize the particulate feed material contained therein to reduce the moisture in such particulate feed material in order to optimize the boiler efficiency.

30. A method for improving a quality characteristic of a particulate feed material in the form of reducing the moisture in the particulate feed material for use in an industrial plant operation producing two different types of waste heat sources and having the particulate feed material delivered to a boiler furnace, such method comprising:

(a) providing a first heat exchanger operatively connected to a hot condenser cooling water waste heat source for transferring heat content from the hot condenser cooling water waste heat source via the first heat exchanger to a fluidizing stream to increase the temperature of the fluidizing stream;

(b) providing a second heat exchanger operatively connected to a flue gas waste heat stream from the boiler furnace for transferring heat content from the flue gas waste heat source via the second heat exchanger to the fluidizing stream that exited the first heat exchanger to further increase the temperature of the fluidizing stream;

(c) delivering the fluidizing stream heated in series via the first heat exchanger and second heat exchanger to a fluidized bed dryer to fluidize the particulate feed material contained therein; and

(d) providing a third heat exchanger located inside the fluidized bed dryer connected to the hot condenser cooling water waste heat source for delivering heat content of the hot condenser cooling water waste heat source via the third heat exchanger to the particulate feed material in the dryer to reduce its moisture content in order to optimize the boiler efficiency.

31. A method for improving a quality characteristic of a particulate feed material in the form of reducing the moisture in the particulate feed material for use in an industrial plant operation producing two different types of waste heat sources and having the particulate feed material delivered to a boiler furnace, such method comprising:

(a) providing a first heat exchanger operatively connected to a hot condenser cooling water waste heat source for transferring heat content from the hot condenser cooling water waste heat source via the first heat exchanger to the fluidizing stream to increase the temperature of the fluidizing stream;

(b) providing a second heat exchanger operatively connected to a flue gas waste heat stream from the boiler furnace for transferring heat content from the flue gas waste heat source via the second heat exchanger to the fluidizing stream that exited the first heat exchanger to further increase the temperature of the fluidizing stream;

(c) delivering a portion of the fluidizing stream exiting the first heat exchanger to a mixing box;

(d) delivering the fluidizing stream exiting the second heat exchanger at the further elevated temperature to the mixing box; and

(e) delivering a blended fluidizing stream containing predetermined portions of the fluidizing stream exiting the first heat exchanger and the fluidizing stream exiting the second heat exchanger to a fluidized bed dryer to fluidize the particulate feed material contained therein to reduce the moisture in such particulate feed material in order to optimize the boiler efficiency.

32. A method for improving a quality characteristic of a particulate feed material in the form of reducing the moisture in the particulate feed material for use in an industrial plant operation producing two different types of waste heat sources and having the particulate feed material delivered to a boiler furnace, such method comprising:

(a) providing a first heat exchanger operatively connected to a hot condenser cooling water waste heat source for transferring heat content from the hot condenser cooling water waste heat source via the first heat exchanger to a fluidizing stream to increase the temperature of the fluidizing stream;

(b) providing a second heat exchanger operatively connected to a flue gas waste heat stream from the boiler furnace for transferring heat content from the flue as waste heat source via the second heat exchanger to the fluidizing stream that exited the first heat exchanger to further increase the temperature of the fluidizing stream;

(c) delivering the fluidizing stream heated in series via the first heat exchanger and second heat exchanger to a fluidized bed dryer to fluidize the particulate feed material contained therein; and

(d) providing a third heat exchanger connected to the flue gas waste heat stream exiting the second heat exchanger for delivering heat content of the flue gas waste heat source via the third heat exchanger to a fourth heat exchanger located inside the fluidized bed dryer to the particulate feed material in the dryer to reduce its moisture content in order to optimize the boiler efficiency.

33. A method for improving a quality characteristic of a particulate feed material in the form of reducing the moisture in the particulate feed material in an industrial plant operation producing two different types of waste heat sources and having the particulate feed material delivered to a boiler furnace, such method comprising:

(a) providing a first heat exchanger operatively connected to a hot condenser cooling water waste heat source for transferring heat content from the hot condenser cooling water waste heat source via the first heat exchanger to a fluidizing stream to increase the temperature of the fluidizing stream;

(b) providing a second heat exchanger operatively connected to a flue gas waste heat stream from the boiler furnace for transferring heat content from the flue gas waste heat source via the second heat exchanger to the fluidizing stream that exited the first heat exchanger to further increase the temperature of the fluidizing stream;

(c) delivering the fluidizing stream heated in series via the first heat exchanger and second heat exchanger to a fluidized bed dryer to fluidize the particulate feed material contained therein;

(d) providing a third heat exchanger located inside one of the stages of the fluidized bed dryer connected to the hot condenser cooling water waste heat source for delivering heat content of the hot condenser cooling water waste heat source via the third heat exchanger to the particulate feed material contained inside that stage of the dryer to reduce its moisture content; and

(e) providing a fourth heat exchanger connected to the flue gas waste heat steam exiting the second heat exchanger for delivering heat content of the flue gas waste heat source via the fourth heat exchanger to a fifth heat contained inside that other stage of the dryer to reduce its moisture content in order to optimize the boiler efficiency.