Method of cooling coal fired furnace walls
A unique method of cooling the interior wall surfaces of gas-fired or coal-fired furnace combustion chambers using carbon dioxide from stack emissions is presented. Carbon dioxide is passed through a tubular structure fixedly attached to the furnace exposed fire-box refractory brick lining heated surface. Carbon dioxide passing through the tubular structure convectively absorbs heat passing through the tube walls of the said tubular structure thereby maintaining the furnace fire-box wall structural integrity at a safe operating temperature. The carbon dioxide exits the tubular structure at an elevated temperature and is collected in a thermally insulated collector manifold for catalytic reaction with high temperature steam and further processing.
The invention relates to my copending application Coal Flue Gas Scrubber, Ser. No. 11/075,218 filed Mar. 09, 2005 relative to the collection and processing of carbon dioxide emissions from coal-fired furnaces.
BACKGROUND OF THE INVENTIONThe invention disclosure describes an improved method of heat transfer that will become necessary to satisfy the additional cooling requirements of environmentally compatible coal-fired furnaces. In most coal-fired furnace designs combustion temperature, depending on fire-box pressure variations, range between 4000° F. and 5000° F. The exposed surfaces of the fire-box wall comprised of refractory ceramic coatings or ceramic tile coatings are used to protect the thermal integrity of the refractory brick internal structural support and lining. Most refractories are compounded for high temperature strength and are poor thermal insulators and require structural backside air cooling passages or water screens to lower the heat transfer rate from the 2000° F. to 2800° F. hot gas wall temperature necessary to assure a practical working gradient across the furnace wall of the heat transferred to the outer steel enclosure and support structure. The invention proposes the use of carbon dioxide as a coolant gas passing through high temperature cooling tubes fixedly attached to the internal exposed surfaces of the refractory brick structure. The coolant carbon dioxide will be obtained from sequestered flue-gas emissions in a gas scrubber described in the cross-reference. The high temperature of the carbon dioxide coolant circulating in vertically spaced cooling tubes lining the fire-box walls exits the furnace at an elevated thermal condition which is maintained in a thermally insulated manifolding facilitating cost efficient low temperature catalytic conversion into a synthetic by-product.
Coal-fired steam generating boilers and furnace refractories have been developed to a very high degree of durability and efficiency since the inception of the electrical generating plant at the turn of the 20th. century. However, with the dwindling supply of cheap natural gas and heavy fuel oils, many of these early types of steam generating boiler systems are being converted to coal-fired systems which produce much higher quantities of carbon dioxide (CO2) and other harmful emissions such as mercury (Hg), sulfur dioxide (SO2) and nitrogen oxides (NOx). This difficulty chronicles in a lesser degree, the greater future concern of the planned increased construction of new coal-fired environmentally friendly systems necessary to keep up with the increasing world demand for electrical power both in the United States and abroad.
The combustion of 1 ton of coal produces 3 tons of CO2 which at the anticipated increase will have a detrimental impact on the world's environment to the extent that it now raises concern of the possibility of creating climate change.
The present invention relates to the cooling of furnace walls and provides the necessary means of conditioning and converting large quantities of CO2 in the production of synthetic gas or other useful products.
SUMMARY OF THE INVENTIONThe invention is a method of cooling gas-fired or coal-fired furnace fire-box walls using gaseous carbon dioxide sequestered from the furnace stack combustion products as described in the cross-reference.
It is the primary purpose of this invention to provide a novel manner of cooling furnace fire-box walls using gaseous carbon dioxide sequestered from the furnace stack combustion products during a preceding process scrubber operation as described in the cross-reference.
It is another object of the invention to provide a means of facilitating the disposal of carbon dioxide by enhancing the means of its high temperature conversion to synthetic gas.
It is yet another object of the invention to decrease carbon dioxide emissions of coal-fired furnaces into the atmosphere.
BRIEF DESCRIPTION OF THE DRAWINGS
Gaseous carbon dioxide is circulated through a tubular circuit lining the refractory brick surface of a furnace fire box. Carbon dioxide passing through the tubular structure convectively absorbs heat passing through the tube walls thereby maintaining the fire-box wall refractory brick structure at a safe operating temperature.
Because carbon dioxide 10 is not as efficient as water as a coolant media, the cooling tubes 9 must operate at a higher temperature and therefore are of seamless construction using materials having high temperature properties such as low-carbon steels, or from steel alloys of molybdenum, chromium, nickel, columbium, or titanium.
Turning now to
Referring now to
- 1. metal enclosure 17. CO2 cooling tube
- 2. beam structure 18. CO2 inlet
- 3. refractory brick 19. CO2 outlet
- 4. hangers 20. manifold
- 5. air-space 21. thermal covering
- 6. x-x interface 22. lower ceramic mounting
- 7. metal plates 23. metering valve
- 8. ceramic pieces 24. upper ceramic mounting
- 9. cooling tubes 25. primary air duct
- 10. carbon dioxide 26. secondary air duct manifold
- 11. water cooling tubes 27. secondary air duct
- 12. ceramic pieces 28. secondary air duct inlet
- 13. CO2 cooling tubes 29. secondary air duct
- 14. water cooling tube 30. ceramic valve housing
- 15. water inlet 31. facility foundation
- 16. water outlet
Claims
1. The use of gaseous carbon dioxide as a coolant media in a furnace fire-box, a refractory brick structure lining the interior surfaces of the said furnace fire-box, a plurality of ceramic pieces mounted on the vertical surfaces of said refractory brick structure, said ceramic pieces holding and providing support and spacing for a plurality of vertically aligned cooling tubes, gaseous carbon dioxide coolant flowing through said cooling tubes, said cooling tubes in communication with a manifold, said carbon dioxide flowing in said cooling tubes exiting the said furnace fire-box passing into said manifold.
2. A furnace fire-box, said fire-box being lined with a refractory brick structure, a plurality of ceramic pieces mounted on the vertical surfaces of said refractory brick structure, said ceramic pieces holding and providing support and spacing for a plurality of cooling tubes, water entering said cooling tubes at the lower end of the said fire-box and exiting the said fire-box at the upper end, said ceramic pieces also holding and supporting a second row of cooling tubes at alternate positions between said water cooling tubes, carbon dioxide coolant flowing in the said second row of cooling tubes, said second row of tubes in communication with a thermally insulated manifold, said carbon dioxide flowing in said second row of cooling tubes exiting said furnace fire-box and passed into said thermally insulated manifold.
3. Claim 2 in which the said water cooling tubes and said carbon dioxide cooling tubes are supported at their upper ends by a ceramic mounting and at their lower ends by a lower ceramic mounting.
Type: Application
Filed: Nov 28, 2005
Publication Date: May 31, 2007
Inventor: Edward McWhorter (Citrus Heights, CA)
Application Number: 11/287,096
International Classification: F22B 7/04 (20060101); F23M 9/00 (20060101);