US2567911A - Liquid cooled smelt discharge spout - Google Patents

Description

P 11, 1951 B. H. MILLER 2,567,911

LIQUID COOLED SMELT DISCHARGE SPOUT Filed Aug. 15, 1947 2 Sheets-Shee; 1

INVENTOR fi 1 Begjamin .HJVfi/ler war/M ATTORNEY Sept. 11, 1951 B. H. MILLER LIQUID COOLED SMELT DISCHARGE SPOUT 2 Sheets-Sheet 2 Filed Aug. 15, 1947 I'NVENI'IA'OR\ V Beg jaminH'Miller i ATTORNEY Patented Sept. 11, 1951 UNITED STATES PATENT OFFICE Application August 15, 1947, Serial No. 768,763

1 My invention relates to a liquid cooled discharge spout for smelting furnaces from which molten materials are continuously discharged, and more particularly to a water cooled spout for use with furnaces in which residual li quor from a sulfateor a soda process of manufacturing paper pulp is incinerated for the recovery of valuable chemicals as a moltensmelt. I

Water cooled trough-like spouts of plate construction with a refractory-lining have heretofore been used to direct the smelt discharge from the tap hole or smelt outletof a chemical recovery furnace. Sucha spout is illustrated in Tomlinson et a1. U. S. Patent 2,161,110. Under some severe operating conditions the plate type of spout construction has not given an operative life commensurate with that of the other parts of the chemical recovery unit. isapparently due to metal deterioration from I overheating caused by non-uniform heat transfer from the smelt to the cooling water leading to cyclic overheating ofthe metal followed byquenching, and possibly to the formation of scale on the water cooled surfaces.

The main object of the present invention is to provide a liquid cooled trough-like spout of contiguous tube sections arranged for a series flow of cooling liquid therethrough t attain a, substantially uniform metal temperature andto avoid zones of excessive metal temperature in the spout. An additional and more specific object is to provid a smelt discharge spout formed by a series of axially spaced U-shaped tube elements with the intertube spaces closed with weld metal to structurally join the sections andto define a continuous metallic smelt confining channel. A further specific object is to provide a smelt spout of the character described characterized by series connected tubular cooling fluid passageways which are non-horizontal in their I heat absorbing zones to avoid steam accumulation on heat transfer surfaces.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its .use, reference should be had to the accompanying drawing and descriptive matter in which I have illustrated and described an embodiment f my invention.

Of the drawings:

Fig. 1 is an elevation view, in section, of a smelt spout constructed in accordance with my 7 Claims. (o1: 263-44) invention and installed in the wall of a chemical recovery furnace;

Fig. 2 is a planview of the apparatus shown in Fig. 1;

Fig. 3 is an end view of the spout, viewed from the left or furnace side of Figs. 1 and 2;

Fig. 4 is a section view taken on line 4-4 of i Fig. 1;

Fig. 5 is anelevation of the U-shaped tubular element at the discharge end of the trough, as viewed from the right in Figs. 1 and 2;

Fig. 6 is an elevation view of a typical U-shaped tubular element from an intermediate position in the spout; and I Fig. '7 is a side elevation view of the tubular element shown in Fig. 6.

The present invention is particularly applicable .foruse with chemical recovery furnaces such as .in the soda or sulfate processes of the pulp and paper industry. A typical recovery furnace for the sulfate pulp process is illustrated in the previously mentioned Tomlinson et a1. Patent The smelt spout of the present invention maybe alternately used in place of the spout disclosed in the patent.

As shown in Figs. 1 to 4, the smelt spout I0 I of the present invention is arranged to cooperate with a smelt tap hole I I for the gravity discharge of smelt from the hearth 15 of a chemical recovery furnace. The construction and operation of the chemical recovery furnace is fully described in the previously mentioned patent. Th jtap hole I l is formed at the elevation of the hearth 15 between adjacent tubes 16 and IT in the. row of tubes Id of the wall 12. The tubes [8 and I! have their lower portions bent out of alignment with the row of tubes 14 to provide spacing for the tap hole which has a width greater than the normal spacing of the tubes M. The tubes I4, [6 and I! are of studded constructionand are covered with a protective coating of initially plastic refractory material on the furnace side of the wall l2.

.The smelt spout I0 is a downwardly inclined spout juncture.

includes a pair of tube coils 20 and 2| arranged in contiguous relationship axially of the spout. As shown in Figs. 1 to 4, the coil 20 is of pear shaped configuration and has an upward and outward extending water inlet connection 24 and an upper cross-over water outlet connection to the coil 2|. The coil 2| has an upper cross-over portion with a downwardly directed outlet connected to the upper side of an adjacent U-shaped tube element 25 of the trough section of the spout H). The coils 20 and 2| are installed in the tap hole II with the plane of the centerline of the tube forming the coil 20 lying in the plane of the axes of the tubes l6 and IT. The spout I is maintained in positionby a mount hereinafter described, so that it slopes downwardly at an angle of approximately 14f. A layer of initially plastic refractory material 22 is applied as a continuation of the furnace hearth into the spout so as to protect the lower surface of the coils 20 and 2|. In addition refractory material is rammed around the sides and top of the coils 20 and 2| to provide an-efiective seal against smelt leakage around the tap hole and This is shown particularly in Fig. l. Studs 23 are provided on the furnace side of the coil 20 and along th lower coil surfaces of thespout so as to anchor the refractory material 22 at the smelt entrance end of the spout. The studded construction of the coil 20 is particularly shown inFig. 3 which is a furnace end view of the coil '20 with the refractory material 22 removed'in part and the tubes l6 and I1 indicated in dot-dash lines to illustrate the installed location of the spout.

The trough section of the spout I0 consists of a unitary assembly of a plurality of spaced tubular elements-joined through the major portion of their contiguous wall lengths by weld metal deposits 39 to define a discharge channel for smelt having'a U-shaped cross-section. Each of th tubular elements consists of a preformed U-shaped tube which is connected with adjacent elements for the flow of cooling water therethrough. With this arrangement of tubular elements, the cooling water entering the element 25 from the coil 2| flows sequentially at a relatively high velocity through elements 26 to and through a U-shaped element 21 at the smelt discharge end of the spout. The element 21 is provided with an outletconnection 28 for the discharge of cooling water from the spout.

Each of the tubular elements -26 is constructed as a unit in a similar manner, but with a progressively increasing width normal to the longitudinal axis of the spout l0 outwardly of the wall l2. The end elements 25 and 21 have a configuration similar to the intermediate elements 26 of the trough section of the spout, but are arranged to receive cooling Water flow from th coil 2| and to discharge the water into the connection 28, respectively, as heretofore described.

A typical U-shaped element 26 is shown in Figs. 6 and 7. Each element consists of two tubular portions joined by a butt weld 29 which, in the spout assembly, lies in a vertical plane common with the longitudinal axis of the spout H1. The progressively increasing width of the spout, between the upwardly extending side wall portions 30 and 3| is varied by the variation in the straight lengths 32 and 33 extending from the center weld 29 and the bend joining the upright portions 30 and 3| and the laterally inclined bottom formed by the lengths 32 and 33.

The tubular elements of the trough section of the spout ID are closely spaced in parallel relationship and are provided with connections for the serial flow of water through each element from the inlet of element 25 from the coil 2| to the outlet connection 28 of the element 27. This is accomplished by providing a close radius bend 34 and 35 on each of the upstanding side wall portions of each element which is perpendicular to the plane of the element. The two bends 34 and 35 on each element face in opposite directions to engage a corresponding bend on each of the adjacent elements. Each of the close radius bends is cut in a vertical plan parallel to the plane of the axes of the upstanding straight sections of the element with the horizontal spacing of the plane equidistant between adjacent elements when the spout is assembled. For example, with the tubular elements 25, 26 and 21 fabricated from 1%" double extra heavy pipe and adjacent elements of the spout assembled on two inch centers, the vertical plane common with the cut face of the bends 34 and 35 will be one inch from the planes of the elements.

To attain the downward slope of the spout H) from the tap hole H, the tubular elements are spaced downwardly in successive equal increments in an amount suflicient to provide the desired angularity of 'slope.- The vertical spacing of the individual elements in the spout assembly necessitates alternate upstanding side wall portions of each tubularelement to have a greater length than the opposite tube side of the same tubular element. The difference in tube side height is equal to the vertical spacing between adjacent tubular elements in the spout assembly.

Referring to Figs. 1, 2, 6 and 7, it will be noted that the straight portion 30 is of greater length than portion 3|. Thus the close radius bend 34 is butt welded to a bend 36 of an adjacent element 26 to form the water flow connection from one element to the adjacentelement outwardly of the furnace wall. The bend 36 is formed with an upright straight section equivalent in length to the section 3|. In a similar manner the bend 35 is butt welded to a bend 31 formed on an upright straight section, equivalent in length to the section 30, of an adjacent element outwardly of the furnace wall. Although the bends 34'and 35 extend through an angle of less than as measured on the tubular centerline, joining the faces of adjoining bends such as 34 and 36, and 35 and 31, permits a turn of water flow through the connections between contiguous tubular sections.

After the tubular elements of the spout are joined by butt-welding the matching bends of successive elements to form a continuous water flow path for the elements of the spout, the intertube spaces are filled with weld metal deposits 39 to form a continuous metal surface for the bottom and sides of the spout I. As shown in the drawings, the weld metal 39 completes the formation of a wall extending approximately the height of the tubular elements 25, 26 and 21, as well as the coils 20 and 2|.

The tubular elements are advantageously fabricated with a wall thickness sufiicient to provide a metallic heat flow path tending to equalize the heat transfer from the heat absorbing spout surface to the wetted wall of the tubular cooling surface. A tendency to equalize the heat transfer through the walls of the spout tends to avoid high temperature zones in the spout which are detrimental to the spout metal and shorten the spout life. with the previously indicated external and 5 internal dimensions of the tubular elements and the described element spacing the thick walled elements with their interposed weld deposits provide suflicient heat transfer capacity to conduct heat to substantially the entire circumference of the elements in contact with the cooling water stream. Such an arrangement provides an internal perimeter of tube in contact with the cooling water stream of approximately 125 per cent of the smelt contacting surface between adjacent tubular element centers. In addition, the minimum metal thickness between adjacent water flow passages is greater than the diameter of the water flow path through the tubular elements. Thus a metallic heat flow path of adequate capacity for heat transfer to the water cooled surfaces of the elements is advantageously provided.

The spout H) is supported in position by a saddle 40 which is mounted upon the furnace wall I 2. The saddle 40 includes a plate 4! positioned in supporting relationship with the bottom of the spout portion adjacent the wall l2. A set of 4 stud bolts 42, spaced in pairs on each side of the longitudinal axis of the spout I0, engage the inclined lower surface of the spout. The plate 4|- is formed with side exttensions 43 which are bent to enclose the sides of the trough l and to stiffen the plate 4|. The extensions 43 are bolted to supporting flanges 49 which are welded to the tubes l6 and H. In addition the plate 4| is bottom supported by a bracket 44 which is affixed to stud bolts 5| welded to the lower ends of the tubes I6 and H. The furnace wall is provided with a box casing 46 which extends outwardly of the furnace casing 41 to enclose'the furnace end of the spout HI and the port so as to avoid smelt leakage through the wall of the furnace. The lower ends of the casings 46 and 41 are supported from a furnace wall header 45. As shown in Figs. 1, 2 and 5, a pair of cables 48 are at-- tached to the furnace wall at a position (not shown) upwardly spaced from the ta hole H, and are secured to support plates 50 welded to the sides of the tubular elements at the discharge end of the spout. The cables support the outer end of the spout and relieve the plate 4| from the support of the overhanging weight of the outer portion of the spout Hi.

In the use of the spout, molten smelt from the associated furnace tap hole is discharged over the spout surfaces for delivery to the dissolving tank as previously described. The spout is maintained in a cool, operative condition by a controlled flow of cooling water which is delivered to the inlet connection 24 at a pressure of the order of 45 p. s. i., and after passing through the serially connected coils 20 and 2| is delivered into the connected upright leg of the U-shaped element 25. In flowing through the element 25 and through each of the serially connected elements 26, the cooling water flows downwardly through each inlet leg, through the bottom portion, and then upwardly through each outlet leg to the inlet leg of the next adjacent element. The water finally flows through the element 21 to the outlet connection 28. The water in entering the coil 20 adjacent the furnace wall progressively absorbs heat in transversing the serially connected passages in the spout walls. Wherever the cooling water stream passes from one U-shaped tubular element of the spout to the next element. the reversal of water flow direction occurs in the bend connection formed, for example, by bends 35 and 31. This position is above the weld metal deposits 39 and is located above the active heat transfer portion of the element wall, so that the reversal of water flow direction is accomplished in a zone of low heat transfer. Air, gas. or vapor separation may take place at this position, but such separation as may take place will not seriously effect the operating temperature conditions of the spout elements.

When the spout is used in connection with a chemical recovery unit of the type described, the spout need not be provided with a protective coating of refractory materials. This is due to the temperature range of the smelt ordinarily encountered. For the sulfate process of residual liquor recovery, the smelt will seldom exceed a temperatureof 1500-1600" F. and for the soda process the smelt temperature will usually be in the neighborhood of 1700-1800" F. However. for higher temperatures, or where desired, the surface of the spout in contact with the smelt or other high temperature fluent materials may be protected by a suitable coating of refractory materials which may be held in position by a studded construction similar to that illustrated for the lower surfaces of the coils 20 and 2|.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

I claim:

1. A smelt spout comprising a tubular coil arranged for the flow of cooling water therethrough. a plurality of spaced U-shaped tubular elements arranged in closely spaced parallel planes to form the sides and bottom of a trough portion of said spout, weld metal deposits filling the intertube space between the bottom portions and part of the side portions of said tubular elements. a water flow connection between said coil and one upstanding side of an adjacent tubular element, and water flow connections between adjacent upstanding portions of said tubular elements on alternate sides of said spout to provide a continuous water flow passageway through said coil and. tubular elements.

2. A smelt-spout comprising a tubular coil arranged for the flow of cooling water therethrough, a plurality of spaced Ushaped tubular elements arranged side by side in parallel planes to form a U-shaped trough portions of said spout, weld metal deposits between said tubular elements cooperating therewith to form a continuous surface along the bottom and to a spaced position on the side elements, a tubular connection between said coil and one side of an adjacent tubular element for flow of water therebetween, and a connecting means for flow of cooling water in series through said tubular elements including a close radius bend on both upstanding side portions of each tubular element butt welded to a corresponding bend on opposite adjacent elements.

3. A smelt spout comprising a plurality of U-shaped tubular elements positioned in spaced parallel planes normal to the longitudinal axis of said spout and arranged for a flow of cooling water therethrough, weld metal deposits filling the intertube spaces between said spaced tubular elements and cooperating therewith to define is continuous surface along the sides and bottom of said spout, the external and internal diameters ofeach tubular element and the element spacing are proportioned with the internal perimeter of each tubular element approximately 125 per cent of the smelt contacting metallic surfaces between adjacent element centerlines.

4. A smelt spout comprising a plurality of U-shaped thick-walled tubular elements positioned in spaced parallel planes normal to the longitudinal axis of said spout and arranged for a serial fiow of cooling water therethrough,

weld metal deposits filling the intertube spaces "betweensaicl spaced tubular elements and cooperating therewith todefine a continuous metallic surface along the sides and bottom of said spout, the minimum metal thickness between adjacent tubular element water flow passages being greater than the diameter of the water flow passage through the tubular elements.

5. A smelt spout comprising a plurality of U-sliaped tubular elements arranged in spaced -parallel planesnormal to the longitudinal axis or said smelt spout to define the sides and bot-- tom-ofsaid spout, and means for cooling said spout by the series flow of cooling fiuid through 'saidtubular elements including a-butt-wclded cooling fluid connection between an upstanding portion of each 05 the adjacent tubular elements;

and a cooling fluid inlet and outlet connection at opposite ends of said spout. -6.-A smelt spout comprising a plurality of upright U-shaped tubular elements arranged in spaced parallel planes, weld metal deposits in -the intertube spaces between said tubular elements to cooperate with said elements in definging the sides and bottom of said spout, each "tubular element vertically spaced in equal increments with respect to adjacent elements to --provide a downward inclination from one end of said spout, and means arranged for the serial inclination from one end of the spout, saidtuburlar' elements having a progressively increased dimension between the upright portions of its u-shapeto=provide .outwardly flaring sides to said spout, and-.means for-the serial flow of cooling water through each of said tubular membersincluding a short radius bend facing and welded to a correspondingbend of opposite adjacent tubular elements, the straight portion below said bends-onalternat'e sides of said tubulanelementshavingya greater length to correspond withthe downward inclination of said n t- 3.;BENJAMIN H. MILLER.

I wais s I D The followingrrefe're'nces are of record in the file of this patent:..:% Z

onrrsnsra'rns PATENTS Number, .Date

-470 51 1, schumacher Mar. 8, 1892 500,336 U Hartman June, 27, 1893 -1,as 1 22 s. V 4 1932 l,883,97 fi 1932 2,268,558 Bailes Jan. 6, 19 2 t' FOREI GN PATENTS 'Numberf Country I Date Great Britain- Jan. 17, 1940

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