US2310698A - Method and means for furnace wall maintenance - Google Patents

Description

Feb. 9, 1943. Hu 2,310,698

METHOD AND MEANS FOR FURNACE WALL MAINTENANCE Filed Oct. 4, 1,940

INVOR.

,2 Ck arles S. Half/op.

Patented F ch. 9, 1943 METHGD AND MEANS FOR FURNACE WALL MAINTENANCE Charles S. Hulton,

Cincinnati, .Ohio, assignor to The Kirk & Blum Manufacturing Company, Cincinnati, Ohio, a corporation of Ohio Application October 4, 1940, Serial No. 359,777

5 Claims.

The present invention relates to a methodand means for furnace wall maintenance and has for an object the provision of an air cooling system for furnace wall maintenance which avoids disadvantages and wasteful practices inherent in all systems heretofore known and used.

A further object of the invention is to provide a means enabling the rapid adjustment of air volume and pressure air applied to the furnace wall under varying conditions of the refractory blocks constituting the wall while the furnace is in operation.

A further object of the invention is to provide means for the purposes stated that may be embodied in existing systems at relatively .low cost.

These and other objects are attained by the means and method described herein and exemplified in the accompanying drawing, in which:

Fig, l is a fragmental, horizontal, sectional view showing a furnace wall retaining the molten glass charge on one side and the cooling system of the invention operatively associated therewith on the other side.

Fig. 2 is a view taken on line '22 of Fig. 1.

Fig. 3 is a view taken on line 3-3 of Fig. 2.

Fig. 4 is a fragmental front elevational view of a nozzle forming a part of the invention.

In the maintenance of furnace walls, such .as refractory block wall structures in glassifurnaces, air streams are directed against the outer wall surface to remove the heat radiated through the blocks for the purpose of retarding the destructive action on the blocks which reduces the thickness of the blocks and ultimately requires replacement of the Wall. The cost of construc-. tion of such walls and the loss involved in shutting down the furnace for the purpose of rebuilding the worn-out walls justifies the installation and operation of air cooling systems that will lengthen the life of furnace walls. .As the wall block thickness decreases during use, increased heat radiation through the block requires more air for its removal. There is a critical limit to the volume and pressure of cooling air for any given block thickness beyond which further surface temperature reduction cannot be obtained by this medium.

In the designing and construction of wall cooling systems provision must be made for air pressure and volume that will be required for the condition existing near the end of the furnace life. Because all of this air is not required during the earlier period of furnace operation, the air source consists desirably of two or more blower units which are connected in parallel and are operable jointly and severally. The nozzles which are positioned closelya'djacent the furnace wall have fixed discharge orifice areas, the size being calculated to pass the air volume and pressure in the cooling system when all blower units are in simultaneous operation. It has been a notable disadvantage of cooling systems for refractory wall maintenance that when less than all of the blower units are in operation, the nozzle discharge velocity is below the desirable point or rate for maximum cooling. The life of the wall is shortened and operating costs are increased due to this condition.

By the method and means of the present invention greater cooling efficiency is attained throughout the life of thefurnac'e wall and since the increased cooling efficiency effects a corresponding increase in the life of the wall, the operator is not required to choose or compromiseion the disadvantages of excessive and wasteful power costs on the one hand and too rapid .destruction of the wall on the other.

The method and means of the present invention are illustrated as utilizing cooling nozzles of the type disclosed in my United States Letters Patent No. 2,042,660, granted June 2, 1936, but the invention herein is not to be considered as limited thereto, since the application of the invention to other systems can be effected in other systems using other methods and other types of cooling nozzles.

Referring now to the-drawing, the furnace wall comprising refractory blocks 10 and the exterior structural steel supporting members l-l, serves to retain a molten charge 12 which is in this instance a mass of molten glass. As will be well understood by those conversant in the art, the substance of blocks 10 deteriorates and erodes under the action ofthe intense heat and the action of the charge itself. This condition is most pronounced on that part of the inner wall surface in the changing range of the surface level of the molten charge.

Mounted adjacent the outside surface of the blocks l0 in this critical area are nozzles 13 connected individually to branch pipes 14 which are connected to a common air pressure main l5. A plurality of independent blower units it, which may be two or more in number, are operable jointly and severally by any suitable means such as individual motors ll and these blower units are connected in parallel to the pressure main I 5.

Nozzles 13 are desirably of the general type disclosed in my aforementioned United States Letters Patent No. 2,042,660 in that the wall of 2 the nozzle has suitably disposed outstanding bosses IS with orifice slots l9 of such size and shape as to discharge ribbon-like air streams upon the blocks in such directions as to afford maximum scrubbing and cooling action. By the present invention the effective size of each discharge orifice or slot is may be varied so that the velocity of the issuing air stream may be adjusted to attain maximum cooling value from each stream throughout the entire life of the furnace wall and under wall thickness conditions requiring air volume from the pressure main that may be provided by one or more than one blower unit. In adapting the nozzles so that the fixed orifice slots can be quickly adjusted as to the efiective discharge area thereof, a mask or valve member 20 is disposed on the inside face of the nozzle and arranged for slidable adjustment lengthwise of the nozzle. The mask is of sheet metal and extends about slightly more than half the inner circumference of the nozzle. On diametrically opposed sides of the valve are welded or otherwise fixedly mounted threaded nuts 2|, the threaded bores of which receive the threaded shanks of wing bolts 22 that extend through vertical slots 23 in the diametrically opposite side of the nozzle casing. The sheet comprising member 20 is cut out intermediate its vertical side edges at vertically spaced intervals providing apertures 24 and 25 so that three transverse edges 25, 21 and 28 may be simultaneously shifted when member 20 is moved for defining the efiective bottom ends of all of the discharge orifices I9. Tongues 29 are formed on edges 26 and 27 and extend out fiat and horizontally through each of the slots IQ of the lower two rows. The top edge 28 has integral troughshaped tongues 30 conforming to the cross-sectional contour of the upper row of slots l9 and extending horizontally therethrough.

It will be seen, from an inspection of Fig. 2, that slots [9 cannot be completely closed but that the orifice area thereof may be adjusted between a maximum orifice area which is substantially the fixed area of the slots l9 and a predetermined minimum eifective area defined between the top of the tongues 29 and 30 and the tops of the slots l9 through which they extend.

The atmospheric temperature in the immediate vicinity of the refractory wall where the cooling nozzles are installed is extremely high due to the effective dissipation of the surface temperature of the wall by the cooling system. The means for adjusting the effective orifice area of the slots is made to be quickly adjusted because the heat can be endured by the workman for only a relatively short time.

The exterior vertical slots 23 define the limits of adjustment of the member 20 and the position of the centers of the wing bolts with respect to the ends of the slots affords a ready means of determining the effective size of the discharge orifices. Any means, for example a tool such as a pair of pliers, not shown, may be used as a gauge, if necessary, to enable the workman to make uniform adjustments on successive nozzles when such adjustments are necessitated by the decrease in thickness of the blocks 10.

The method of wall cooling of the present invention provides that the discharge orifices of the nozzles have the areas thereof initially reduced so that the air volume required and supplied by but one of the blowers will issue at a velocity which will most effectively dissipate the surface temperature of blocks I9 when they are new and of full thickness. In the present embodiment this adjustment is made in the cooling system before putting the newly constructed furnace into operation and the orifice size selected according to the controlling factors of the furnace, viz., the kind of refractory material, the size of the blocks, the nature and melting temperature of the charge, and the rate removal of the molten material with respect to the extent of melting area in the furnace. By initially providing not only the requisite volume of air but directing it upon the surface at the most effective velocity, the rate of decrease of the wall thickness is reduced. When the deferred reduction in the wall thickness comes to pass and a greater volume of air is required, another blower is brought into service concurrently with the first. The velocity of the air streams of increased volume is adjusted to optimum cooling efficiency by lowering the members 20 in nozzles l3 to correctly increase the size of the discharge orifices. By making the proper adjustment of the size of the discharge orifices, the wasteful practice of expending excessive amounts of power with less than maximum efficiency is eliminated. The actual life of the furnace wall is greatly increased because during no part of the period of its continuous operation does the air volume or velocity deviate from the known optimum efficiency cooling requirements.

What is claimed is:

1. The method of air cooling furnace walls and the like which comprises applying to the surface thereof cooling pressure air at spaced locations and in predetermined relatively low volume and at optimum efficient high velocity when the wall is new and thick whereby the rate of deterioration of the wall is retarded, maintaining said pressure and velocity of the said air streams until the wall thickness has decreased under prolonged furnace operation, then increasing the volume of the air supply for said air streams and increasing the size of said air streams whereby optimum efficient surface temperature reduction is established at predetermined air velocity and volume for said reduced wall thickness whereby the rate of deterioration of the thinner wall is delayed.

2. The method of air cooling furnace walls and the like which comprises applying to the surface thereof cooling pressure air at spaced locations and in predetermined relatively low volume and at optimum eficienct high velocity when the wall is new and thick whereby the rate of deterioration of the wall is retarded, maintaining said pressure and velocity of the said air streams until the wall thickness has decreased under prolonged furnace operation, then increasing the volume of the air supply for said air streams and increasing the size of said air streams whereby optimum efficient surface temperature reduction is established at predetermined air velocity and volume forsaid reduced wall thickness whereby the rate of deterioration of the thinner wall is delayed, and repeating the latter steps at intervals on the basis of retarded decrescence of wall thickness.

3. The method of air cooling furnace walls and the like which comprises impinging the wall with air pressure in angularly divergent ribbons of an initial cross-sectional size and at a pressure and a volume affording optimum surface temperature reduction on the basis of initial wall thickness, maintaining said volume and pressure of the cooling air ribbons until appreciable reduction in wall thickness occurs, then increasing the volume of cooling air and increasing the cross-sectional size of the cooling air ribbons whereby a predetermined optimum surface temperature reduction is established in relation to the wall.

4. In a wall cooling system the combination with a wall to be cooled, a series of spaced nozzles for directing cooling air streams on said wall a common pressure air main feeding said nozzles, a plurality of blower units connected in parallel to said main, said units operable jointly and severally, and means carried by the nozzles for selectively modifying the cross-sectional areas of the air streams whereby selected pressures are maintained under varying air supply volume from the blower units.

5. A wall cooling system comprising an air pressure main, a plurality of jointly and severally operable blower units providing selected air volume to said main, a plurality of nozzles having fixed discharge orifices for directing the maximum volume of the combined blower units at a predetermined velocity and means carried by said nozzles for reducing the effective size of the discharge orifices whereby selected air velocity is attained during operation of less than all of the blower units.

CHARLES S. HULTON,

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