Furnaces – Ash receiving and handling devices – Ashpans
Patent
1981-01-02
1983-06-14
Jones, Larry
Furnaces
Ash receiving and handling devices
Ashpans
110166, 110169, 126242, F23J 102
Patent
active
043876510
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
In coal-fired steam generators, the manner in which the ash is handled and disposed of is an item of considerable importance. One means used today for continuously removing ash and slag which falls through an opening in the furnace bottom is a scraper conveyor which is submerged in a tank of water. When the unit is shut down for periodic maintenance, it is desirable to be able to move the entire scraper conveyor unit, including the tank in which it is housed, from beneath the furnace so that it can be easily worked on, and so that it can be replaced with another unit if major repair is required.
A water seal is generally provided for preventing the atmosphere from being exposed to the furnace interior. This consists of a plate extending down and surrounding the furnace bottom opening, which plate extends into the submerged scraper conveyor tank, which tank is filled with water, thus forming a water seal. This type of seal is provided because it allows the furnace to grow relative to the submerged scraper conveyor unit caused by thermal expansion. Large furnaces are generally top supported, so that they are free to expand in a downward direction when the unit is first started up. This growth can be on the order of 10-12" from the cold to the hot condition.
The above provides the problem of how to be able to quickly remove the submerged scraper conveyor unit from beneath the furnace when the unit is shut down for maintenance. In the past, it has been necessary to allow the unit to cool down to a point where workmen can unbolt the seal plate from the furnace bottom. This cooling and unbolting time is considerable and can cause the entire steam generator to be down for lengthy maintenance periods.
SUMMARY OF THE INVENTION
In accordance with the invention, a submerged scraper conveyor unit is provided beneath a coal-fired furnace and a water seal is provided therebetween to prevent the furnace gases from escaping to the atmosphere. This water seal is formed by providing plate means extending down from the furnace bottom into the water-filled submerged scraper conveyor tank. The upper end of the plate means forms a seal with the furnace bottom. The plate means are capable of being moved upwardly and downwardly by a hydraulic or electric motor so that it can be moved downwardly into sealing relationship during operation of the furnace, and can be moved to its up position during a maintenance shutdown so as to permit the submerged scraper conveyor tank to be removed from under the furnace.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional side view of a submerged scraper conveyor unit and its associated furnace constructed in accordance with the invention; and
FIG. 2 is a view taken on line 2--2 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Looking now to the drawings, numeral 10 designates a furnace or a transition chute which is attached to a furnace of a steam generator in which coal is burned. Molten ash and slag are discharged through the furnace bottom or transition chute opening 12, and falls into the submerged scraper conveyor unit 14. The tank 16 is filled with water 18 and contains a conveyor belt 20 with integral scraper blades in the bottom thereof, by means of which the cooled ash and slag is continuously removed from the tank (FIG. 2). The upper run of the conveyor 20 carries the clinkers to the end of the tank, where they can be discharged into trucks or onto a mechanical conveyor (not shown) and transported away. A portion of the water in the tank is constantly removed and replenished (while maintaining a given water level) to maintain the main body of water at a temperature not exceeding 160.degree. F.
A water seal permits thermal expansion of the top-supported furnace 10 while preventing exposure of the interior thereof to the atmosphere. The water seal is formed by plate 24 which is secured to the bottom of the furnace and extends downwardly into the water in tank 16. The plate 24 extends around the entire periphery of the opening 12, so as to com
REFERENCES:
patent: 1169017 (1916-01-01), Duckham
patent: 1867794 (1932-07-01), Allen
patent: 3094953 (1963-06-01), Alexander
patent: 3915105 (1975-10-01), Michelbrink
patent: 4300457 (1981-11-01), Moore
Combustion Engineering Inc.
Jones Larry
Olson Robert L.
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