Liquid heaters and vaporizers – Subsidiary
Patent
1992-11-10
1993-12-28
Favors, Edward G.
Liquid heaters and vaporizers
Subsidiary
122 7R, 12223511, 12223515, 1223673, F22B 3300
Patent
active
052730026
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a water tube boiler, particularly of the type comprising a furnace having at least one burner located in its upper part to generate a generally downwardly directed flame into the furnace, a substantially vertical flue gas stack located close to one side of the hearth and having an inlet for the flue gases at its lower part which is situated in a lower part of the furnace, an outlet for flue gases located at its upper part, a convection tube assembly arranged in the stack for the recovery of heat from flue gases passing through the flue gas stack.
In conventional steam boilers of this type, the convection tube assembly arranged in the flue gas stack generally consists of a plurality of layers of substantially horizontal tubes located one above the other. Occasionally substantially vertical convection tubes have been used. However, the efficiency of the convection part of that boiler has been comparatively low. Both types of known constructions have been found in practice to be highly unfavourable regarding the extent of and difficulty in performing the operations required to repair the convection tube assembly after the appearance of a leak in any tubes.
SUMMARY OF THE INVENTION
The object of the invention is to effect an improved water tube boiler of the type described which enables repair work on the convection tube assembly to be performed in a considerably simpler and quicker manner than was previously possible.
The boiler according to the invention has its convection tube assembly comprising a plurality of parallel rows of substantially vertical convection tubes extending along a substantial portion of the length of the flue gas stack and the tubes are provided externally with surface enlarging elements. The tubes in each row are joined together to form a flat coherent unit with the aid of an upper, substantially horizontal header to which the upper ends of all convection tubes in the row are connected, and a lower, substantially horizontal manifold to which the lower ends of the convection tubes are connected. The headers of the various units are connected individually to a steam drum of the boiler, and their manifolds are connected individually to a stuff box in the boiler.
By this construction of the convection tube assembly, when a leak occurs in a convection tube, the flat unit comprising a row of convection tubes which includes the damaged tube can be cut free and removed from the flue gas stack. The damaged tube can then easily be repaired or replaced by a new tube. The flat unit of convection tubes can be cut free by cutting each of the two tubes connecting the unit's header with the steam drum and its manifold to the stuff box of the boiler. Furthermore, providing the convection tubes with external surface enlarging elements avoids the drawback of previously known steam boilers having substantially vertical convection tubes, i.e. low efficiency in the convection part of the boiler, and instead enables high efficiency there.
With the object of reducing the resistance of the substantially horizontal headers and manifolds in the convection tube units to the upwardly directed flow of flue gases in the stack, both headers and manifolds may be arranged mutually displaced in a substantially vertical direction between adjacent units. The headers and manifolds are suitably arranged displaced in alternate upward and downward directions between the various units.
To facilitate advantageous placement of suitable mechanical supports for the convection tubes and equipment necessary for soot blasting, the convection tubes may be provided externally with surface enlarging elements only along selected portions of their length. In this case, they may suitably be provided between such parts with parts which are free from external surface enlarging elements.
The distance of diversions between the convection tubes may suitably be the same within each unit and between the various units. This ensures uniform distribution of the convection tubes through
REFERENCES:
patent: 3559624 (1971-12-01), Sheikh
patent: 4422411 (1983-12-01), Thorogood
Andersson Erik
Balint Endre
Favors Edward G.
Gadelius Sunrod AB
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