Liquid heaters and vaporizers – Industrial – Port
Patent
1986-06-26
1988-01-05
Dority, Jr., Carroll B.
Liquid heaters and vaporizers
Industrial
Port
122235B, 1101825, 110338, F22B 3700
Patent
active
047168579
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a furnace wall, especially of an incinerator, comprising secondary air feed nozzles.
As a general rule the walls of incinerators, especially those for burning urban waste, comprise secondary air feed nozzles.
These walls generally contain a bundle of tubes for heating water circulating within them for subsequent recovery of the thermal energy thus obtained. The nozzles, which pass through the wall, are thus necessarily inserted between neighbouring pipes to feed secondary air into the furnace from feed means.
The walls are generally of refractory materials, specifically in the form of bricks, which are not subject to corrosion. It is known that burning waste produces sulfides (especially CaS, Na2S and FeS) which make the environment inside the furnace especially corrosive.
The secondary air feed nozzles usually project from the inside wall of the furnace. The disadvantage of this is that the projecting part is exposed to the corrosive action of the air laden with sulfides inside the furnace.
This major disadvantage has been overcome in part by surrounding the projecting parts of the nozzles with cement so that only the nozzle opening is exposed. Nevertheless, the inside wall of the nozzle remains in contact with the corrosive air inside the furnace through this opening. Also, ash and waste materials volatilized during combustion tend to collect on the projecting parts. They are rich in sulfides as they have not been completely combusted. This creates two problems which tend to aggravate each other: on the one hand, the sulfides collecting in this way on the projecting parts are even more corrosive than the surrounding environment; on the other hand, they tend to clog the nozzle outlets and so to worsen combustion conditions by reducing the input of secondary air. As is well known, incomplete combustion increases the concentration of sulfides, which are reduced to solid sulfates only on complete combustion. There therefore results a self-perpetuating phenomenon resulting in fouling and corrosion of the furnace, and there may be no remedy for such corrosion.
It is, of course, possible to shut down the furnace periodically in order to clean it and where necessary replace any excessively corroded parts, but this has obvious major disadvantages which are better avoided.
The object of the present invention is to circumvent the disadvantages mentioned hereinabove by proposing, in accordance with the invention, a furnace wall, in particular an incinerator furnace wall, of the kind constructed of elements assembled in the manner of bricks of which certain elements are hollow and constitute nozzles for feeding secondary air into the furnace, said elements being disposed around pipes adapted to convey a cooling fluid, the pipes being disposed in bundles and constituting a metal framework for the wall, characterized in that each nozzle-forming element is in two parts each formed with a longitudinal recess mated together at a substantially horizontal jointing surface and in that the nozzles discharge into the furnace through a generally plane face of the element continuously merging with the corresponding faces of the adjacent elements.
This makes it possible to construct a furnace the walls of which are smooth and offer no opportunity for waste materials, especially sulfides, to accumulate. Moreover, in this way the use of metal, which is subject to corrosion, is avoided through the use of the longitudinal recesses in the two parts which are made of a refractory material, such as silicon carbide, for example.
Also, such nozzles are particularly simple and economical to manufacture, as the refractory material is easily molded.
The characteristics and advantages of the invention will emerge from the following description given by way of example with reference to the appended drawings, in which:
FIG. 1 shows in longitudinal cross-section an element forming a nozzle in accordance with the invention;
FIG. 2 shows in plan view an element forming a nozzle in accordance with the invention;
FIG.
REFERENCES:
patent: 955387 (1910-04-01), Crosthwaite
patent: 1791244 (1931-02-01), Nygaard
patent: 1968934 (1934-08-01), Finn
patent: 2139004 (1938-12-01), Davey
patent: 2532990 (1950-12-01), Blaha
patent: 3221680 (1965-12-01), Reintjes et al.
patent: 3589318 (1971-06-01), Szatkowski
patent: 3828509 (1974-08-01), Ottmar et al.
Brown Charles A.
Brown Charles E.
Dority Jr. Carroll B.
Electricite de France
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