US2024198A - Furnace structure - Google Patents

Description

Dec. 17, 1935. BAILEY 2,024,198

FURNACE STRUCTURE Original Filed Nov. 18, 1950 s sheets-sheet 1 INVENTOR ATTORN E13 Dec. 17, 1935. E. e. BAILEY 2,024,198

FURNACE STRUCTURE Original Filed Nov. 18, 1950 3 Sheets-Sheet 2 ma ommquonuqmm II n I' I VTOI? FIG.3 zr s NJWYQ W ATTORNEU Dec. 17, 1935. I E. G BAlLEY 2,024,198 I FURNACE STRUCTURE Original Filed Nov. 18, 1930 3 Sheets-Sheet 5 FIG. 4.

a av NTOR ATTORNEYS Patented Dec. 17, 1935 UNITED STATES PATENT OFFICE FURNACE STRUCTURE of Delaware Application November 18, 1930, Serial No. 496,397 Renewed March 16, 1935 3 Claims. (Cl. 122-235) This invention relates to a furnace that is especially adapted for burning powdered-fuel in which slag from the fuel is permitted to collect upon' the floor of the furnace in a molten form and is drawn off at intervals.

In furnaces of this character that have been used heretofore, troubles have arisen when the slag is permitted to freeze and subsequently expand when again heated, with the result that the furnace walls are pushed outwardly. This danger is sometimes caused because when the slag cools and freezes, cracks form in it which subsequently receive more molten slag that hardens therein, thus causing the slag slab to grow and expand by successive heating and cooling.

By the present invention, the danger of the walls of the furnace being forced outwardly is obviated by forming the floor in such a manner that the slag that collects upon the floor has thin edges that would be crushed without pushing the furnace walls out. The floor is water cooled by means of rows of tubes through which water passes and the floor slopes from opposite sides of the furnace towards the middle.

The invention will be understood from the description in connection with the accompanying drawings, in which Fig. 1 is a vertical section through an illustrative embodiment of the invention; Fig. 2 is a section along the line 22 of Fig. 1; Fig. 3 is a section along the line 33 of Fig. 1; and Fig. 4 is a section along the bottom of a furnace showing a modification.

In the drawings, reference character I indi-' cates a furnace that is provided with one or more fuel burners 2. Vertically disposed water tubes 3 extend along the front and rear walls of the furnace and vertically disposed water tubes 4 extend along the side walls of the furnace. The tubes 3 and 4 are covered with tile or the wellknown Bailey blocks 5 to form continuous walls. The lower ends of the tubes 3 extend straight downwardly into horizontally disposed headers 6 and the lower ends of the tubes 4 extend straight downwardly below the floor of the furnace and then outwardly into horizontally disposed headers 6'. The upper ends of the tubes 3 and 4 extend outwardly into horizontally dis posed upper headers I. Recirculating tubes 4' may connect the headers 6' and 1 outside of the furnace.

Downtake tubes 8 extend downwardly from the headers I to headers 8 outside of the furnace. Tubes 9 extend from the headers I to the steam space of the steam and water drum III of the water tube boiler that is located above the furnace I.

A row of tubes I I extends from each front and rear header 6, the upper portions of these tubes sloping downwardly towards the middle of the 5 furnace, as indicated at I2, into proximity to each other. A row of tile I3 closes the space near the middle of the floor of the furnace between the tubes II, and tile or Bailey blocks I4 extend from the blocks I3 along the portions I2 of the 10 tubes II to complete the furnace floor. The tubes II extend downwardly and outwardly from the furnace I3 into headers I5. Tubes I6 extend from the headers 8 into the headers I5. Tubes I1 extend from the water space of the steam and water drum ID to the headers I5. I

A slab or strip of refractory material I8 extends along the topside of the blocks I3 and slag from the fuel that is burned in the furnace I collects upon the floor of the furnace, as indicated at I9, and may be tapped out through the slag tap opening 20 when desired.

As the molten slag I 9 collects upon the sloping floor of the furnace, the edges thereof are thin, as shown most clearly in Fig. 1, so that the danger of the slag forcing the side walls of the furnace outwardly by expansion is obviated, as the thin edges of the slag when cold will be crushed without pushing the walls outwardly.

The front and rear furnace walls as well as the floor of the furnace are cooled by water passing from the steam and water drum I0 through the pipes I'I, headers I5, tubes II, headers 6, tubes 3, headers 1 and tubes 9 into the steam space of the steam and water drum I0. Water. also circulates locally through the tubes 8, headers 8' and tubes I6 from'the headers l to the headers- I5. The side walls of the furnace are similarly cooled by a circulation of water through connections (not shown) from the steam and water drum I II of 40 the boiler and by local circulation through the tubes 4'.

Even if the floor of the furnace is not liquid tight at the beginning, some of the molten slag from the fuel freezes when it comes into contact with the floor and fills up the crevices, so that a. liquid-tight floor as well as liquid-tight joints between the edges of the floor and the walls of the furnace can be maintained.

Instead of having the furnacebottom tubes covered with bare'tile upon which the slag collects, the tubes may be covered with tile and the tile then covered with a coating of heat insulatmg refractory material so that there willnot be such a rapid heat transfer to the water tubes as to cause too thick a layer of slag to freeze upon the floor of the furnace.

In the modification shown in Fig. 4 the portion I 2 of the tubes ll along the floor of the furnace is made less sloping than the corresponding tubes shown in Fig. 1, and the layer of tile or blocks I4 is coated with a refractory material preferably of the sort that may be kept in. a substantially granular form under conditions of use in the furnace. In this way when the slag is tapped out through the opening 20 substantially all of it canbe drained out, thus leaving a very thin layer of slag on the floor of the furnace. For this purpose a coating 2| of magnesite may be provided along the furnace bottom, being thinned out and carried on the inclined surfaces, practically up to the junction headers at the sides of the furnace. Other materials such as pirites and iron sulphide may be mixed with the magnesite which will assist in sintering and bonding the magnesite together. Other refractories, such as dolomite, chrome ore and mullite may be used, as such materials resist the action of slag and its ingredients. By withdrawing substantially all of the slag from the slag tap opening only a thin mat of slag will remain on the floor to exert thrust against the side walls of the furnace. At the same time the refractory material in contact with the inclined water cooled surface of the floor will remain in a somewhat granular condition and will therefore exert very little, if any, thrust on the side walls of the furnace.

I claim:

1. In a furnace, two sets of water cooling tubes 5 having upright sides, a floor comprised of two 15 oppositely extending covered cooling tube portions constructed to sustain molten slag, said portions having an inclination less than 20, and

a slag run-off in one of the remaining upright sides at an elevation permanently maintaining 0 a slag pool level the pool margins on the inclined floor portions of which are prevented from rising except on the slight inclinations and are thereby consistently in attenuation presenting minimum holding resistance to expansion and 25 contraction and enabling them to become fluid substantially immediately upon starting the furnace.

ERVIN G. BAILEY. 8o

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