US1811373A - Furnace wall - Google Patents

Description

June 23, 1931. c THAYER 1,811,373

FURNACE WALL Filed Oct. 11, 1927 5 Sheets-Sheet l A TTORNEY 5 Sheets-Sheet 2 It. I! I b mv-: m m4 w 2 v Tl l fN TO B) 'ATTORN Y June 23, 1931. H. c. THAYER FURNACE WALL Filed Oct.

June 23, 1931. H. c. THMFER FURNACE WALL Filed Oct. 11, 1927 5 Sheets-Sheet 3 ATTORNEY H. C. THAYER A FURNACE WALL June 23, 1931.

Filed 001:. 11. 1927 5 Sheets-Sheet 4 'ATTOR 'EY June 23, 1931. 1 H. c. THAYER FURNACE WALL Filed Oct. 11, 1927 5 Sheets-Sheet 5 16 ATTOR EY Patented June 23, 1931 UNITED STATES PATENT OFFICE HOWARD C. THAYEB, OF JERSEY CITY, NEW' JERSEY, ASSIGNOR TO BERNITZ FURNACE APPLIANCE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSA- OHUSETTS FURNACE WALL Application filed October 11, 1927. Serial No. 225,522.

In modern boiler plants the temperatures created, run so high that it has now become a common practice to use wall constructions or facings of highly refractory material and also to make some provision for cooling the walls. If some means is not provided to cool the lining it will become heated to such a degree that its surface is softened or rendered somewhat plastic so that slag and clinker will stick to it. When these accumulations are removed a part of the lining is chipped off and as these operations are repeated from time to time the surface of the wall becomes worn away to such an extent that the lining must be renewed.

One method of keeping the temperature of the lining below the point at which slag and clinker will adhere to it has been to embed pipes or tubes in the wall and to circulate water or steam through these pipes or tubes, the heat taken away from the wall by the water or' other circulating medium being used in the-boiler. Such walls will be herein referred to as water cooled walls regardless of the circulating medium used, the nature of the furnace, or the position in the furnace. J

The present invention is especially concerned with walls of this type. It aims to improve these wall constructions with a view to reducing the expense of manufacturing them while still providing a thoroughly satisfactory and highly efiicient wall structure. The invention involves both a novel wall construction and also novel units or elements for use in such walls. The nature of the invention will be readily understood from the following description-when read in connection with the accompanying drawings, and the novel features will be particularly pointed out in the appended claims.

In the drawings,

, Figure 1 is a front view of a. portion of a water cooled wall constructed in accordance with this invention;

Fig. 2 is a cross-sectional view on the line 22, Fig. 1;

Fig. 3 is an elevation showing substantially the manner in which the wall shown in Fig.

2 would appear with the back casing and in- Fig. 5 is a perspective view of one of the refractory blocks or bricks used in the wall shown in the figures above described;

Fig. 6 is a perspective view of the clamp plate used with the brick shown in Fig. 5;

Fig. 7 is a perspective view of the bolt which preferably is used with the clamp and brick shown in Figs. 5 and 6;

Fig. 8 is a. horizontal cross-sectional view showing, on a larger scale, a portion of the construction shown in Fig. 2;

Fig. 9 is a horizontal cross-sectional view on a relatively large scale of the clamps which hold the tubes in alinement and shows the refractory blocks in their cooperative relationship to these clamps;

Fig. 10 is a perspective view showing a portion of one of the clamping bars shown in Fig. 9;

Figs. 11, 12 and 13 are vertical cross-sectional views at the upper part of the wall showing different arrangements for supporting the tubes;

Figs. 14: and 15 are horizontal cross-sec-' tional views showing modified embodiments refractory blocks or bricks 3 which protect the tubes at the front or fire side of the wall. Fastening devices including clamping plates 4 cooperate with each block 3 to secure it to the tubes. At the rear of the tubes, and spaced from them, is a casing including sheet metal panels'or sections 5 which are secured to and supported by upright means 6, and this in mind, the various details of the construction will be better understood. Referring more particularly to Figs. 3, 4, 9 and 10 it will be seen that the tubes 2 are held in their roper positional-relationship to each other y a series of clamps, each comprising a bar 8 provided with a plurality of approximately semi-circular recesses, one. of which is best shown at 9 in Fig. 10. These recesses are designed to receive the tubes 2, as clearly shown in Fig; 9. The tubes are clamped rigidly in these recesses by U-bolts 10, each bolt embracing a tube and having its legs extending through the bar 8. Nuts 12 are threaded on the ends of these legs and serve to draw the bolts firmly backward so that the clamps may be secured very tightly to the tubes. Preferably two U-bolts are used, one aboveland the other below, the central projecting part of each clamping bar 8, as

clearly shown in Fig. 4. Several horizontal series of these clamps are used, two such series being shown' in Figs. 3 and 4, and one series is spaced longitudinally of the tubes from the other by a considerable distance. Preferably the individual clamping bars 8 in the two series are staggered with refer ence to each other, as clearly show in Fig. 3. Consequently, these clamps secure the tubes of the wall in a. definite spaced relationship to each other and hold the tubes securely in alinement.

The refractory blocks 3 are mounted between the clamps 8-8, and a very substantial part of the weight of these blocks is supported by the clamps. These blocks are made of some highly refractory material, preferably silicon carbide.

Figs. 5 to 8, inclusive, show more clearly the various details of construction of an individual block and the fastening means which holds it in position in the wall. It will be seen from an inspection of these views that the block 3 includes a front wall a on which the face I) which is exposed to the fire is formed, the entire thickness of the wall a serving to protect the tubes 2. Projecting rearwardly from this wall a and located between the tubes 2 is an extension or tongue 0, and this tongue has a T-shaped slot d formed tlierejthrough from side to side to receive the head a of a bolt 14 which forms part of the fastening or clamping means for the blocks. The bolt 14 projects through the clamping plate 4 and a nut 15 threaded on the bolt cooperates with it and the plate 4 to draw the block 3 backwardly into contact with the tubes 2. It will be observed that the clamping plate 4 bridges two adjacent tubes and is provided withupright faces 16'16, Figs. 6 and 8, to bear against the tubes. The block 3 also has upright curved faces f to bear ing bars 8, above referred to, to take at least a substantial part of this Weight. This arrangement, however, makes a very solid substantial construction in which the parts are easily assembled and which provides for the expansion and contraction of the indi-'' vidual blocks and of the tubes.

As above explained, the front face of the wall, or that exposed to the fire, is subjected to extremely high temperatures, and the chief purpose of the tubes 2 is to conduct a circulating medium whichtakes away a portion of this heat and thus holds the temperature of the lining below the point at whiqh the surface of the refractory blocks 3 will soften and permit clinker to adhere-to it. I have found that the heat transfer from the refractory blocks to the tubes can be improved materially by using a cement between the blocks and tubes which, instead of being a heat insulator, is a conductor of heat. Silicon carbide cement preferably is used.

Referring to Fig. 8 it will be seen-that a very considerable part of the space between each of the tubes 2 and the block 3 is filled in with cement 17. The sides ofthe tonguec are cut away or grooved vertically at the rearward side of the faces ff .to provide s ace for this cement, as clearly shown in igs. 5 and 8, and I prefer, also, to provide horizontal grooves g in these faces to assist in locking the cement in place. As a further means of holding this cement while it sets the lower margin of the clamping plate 4 is provided with an inwardly extending flange 18, Figs. 4, 6 and 8, which closes up a part of the space between the clamping plate 4 and the block 3 at the lower portions of these members.

It is desirable to prevent any substantial leakage of airthrough the furnace wall, and for this purpose I prefer to seal the joint between the clamping, plates 4 and the tubes 2 by cement or in some equivalent way. As best shown in Figs. 6 and 8, the curved faces .16 of the plate 4 which contact with the tubes are grooved, as indicated at 20, to receive cementor some suitable sealing material and thus close this vertical joint. The horizontal. oints between adjacent clamps may also be sealed with cement, asbestos tape, or other suitable material, as shown at 21 in Figs. 3

and 4, and the same construction may be used between the ends of adjacent clamping bars 8 and also between the upper and lower surfaces of these bars and the plates 4. It usually is preferable, also, to set the blocks 3 in an air setting cement which closes the horizontal joints 22, Figs. 1 and 4, although I preferto leave the vertical joints 23 open.

Leakage'of air or gas through the Wall is further prevented by the casing 5. shown this casing is supported by upright beams 66, Fig. 2, and the sheet metal panels 5 extend from the flange of one beam to the flange of the next adjacent beam. At each beam the margin of the panel or section is clamped in position by an angular strip 23, Fig. 2, a packing stri 24 of asbestos or the like being interposed etween the margin of each sheet metal section and the flange of the beam. At,the horizontal joints between the sections 5 inner and outer reinforcing bars 25 and 26, respectively, are used (see Figs. 2 and 4), these two bars overlapping the margins of' adjoining sections and being bolted together so that they clamp these margins securely between them. The inner bar 25 is grooved to receive packings 27, Fig. 4, of asbestos or any other suitable material,-which make practically a gas tight-joint at these points. There is relatively little difference in gas pressure at the two sides ofthe wall, so that a construction of this character makes practically a gas tight wall.

The heat insulating material used between the rear casing 5 and the rear surfaces of the clamping plates 4 may consist of any suitable material. A common construction is to use a layer of insulating cement at the backs of the clamping plates and then a layer of rock wool between this layer of cement and the casing 5.

' Fig. 14 shows a construction substantially like that shown in Fig. 8 except that the T- shaped slot in the block 3 which receives the bolt 14 is located vertically instead of horizontally, and this bolt is embedded in heat insula-tlng cement which assists in protecting it from the action of the hot gases and high temperatures.

Another modification is shown in Figs. 15

and 16 in which the rearwardly extending tongue of the block 3 is provided with a. slot 29 to receive a bar 30 which cooperates with the fins 31 of the tubes 2' to fasten the blocks in their cooperative relationship to the tubes. In this construction, also, the vertical grooves 32 inthe block which are provided to receive cement 17 stop at a short distance above the bottom of the block. In other words, the lower art of this block is provided with a short ange, the upper side of which terminates at the line 33, Fig. 16, and which serves to retain the cement while it is setting.

Fig. 17 shows a construction much like that shown in Fig. 15 except that the bar 30 is tapped to receive screws 33-33 which bear against the fins 31.

In the construction shown in Figs. 18 and 19 the rearwardly extending tongues of the refractory blocks 3 are simply grooved verticallyat each side to receive the fins 31, the fins thus acting to lock the blocks in place.

In some of these blocks the faces are plain, as shown in Fig. 5, while in others, as for example in Figs. 14, 18 and 19, the faces are corrugated, one face construction being preferred in some installations and another un-- der different conditions.

Another modification is shown at Fig. 20 in which refractory blocks 34 of quite a different shape are used, and at the side of the tubes 2 opposite the fire faces of the blocks another refractory block 35 is set into recesses formed in adjacent blocks 3434. The block 35 bears against the rear side of the tube and cooperates with flanges on the blocks 34-34 at each side of it to lock them against the tubes.

Figs. 11, 12 and 13 show arrangements which may be provided for supporting the tubes to permit longitudinal expansion and contraction of them. In Fig. 11 the upper ends of the tubes are joined to a header 36 which is supported at intervals by heavy springs 37. In many constructions, however, the tubes are curved at their upper ends, as shown'in Figs. 12 and 13, and where such a construction is employed I prefer to support the tubes at points adjacent to one header in fixed positions by clamps or yokes 38 which are secured to one of the beams of the wall. This holds the tubes firmly in position while allowing them to expand away from this supporting point and at the same time relieves the joint between the tubes and the header 36 of the weight of the tubes.

While I have described the invention as applied more especially to a typical steam boiler installation, it will be understood that walls embodying this invention are applicable to a great variet of furnace structures and that, consequent y, the medium circulated through the pipes ortubes embedded in the wall may consist of any one of a. great forded by the use of a heat conducting cement to unite the refractory blocks and tubes.

circumstances, a cement which is a conductor of heat. By properly selecting or mixing the cement the rate of heat transfer to the'tubes can be controlled. A silicon carbide cementaifords a relatively high rate of heat transfer, while a fire clay cement afi'ords only a very low rate. The two cements, however, can be mixed together in suitable proportions to make a degree of heat conductivity which will vary greatly. Other cements or mixtures of cement also can be used. The heat conductivity can be proportioned to that of the refractory blocks so that the rate of heat transfer can be suited to the conditions obtaining in any particular installation, and the results desired'in such installation.

An important advantage of this feature of the invention consists in controlling the thermal storage in the refractory blocks so that the temperature at the face of the block will be regulated more accurately, this bein de-' sirable not only from the standpoint of preserving the refractory wall or lining, but also incontrolling the temperatures a. short distance away from the fire face of the wall such a manner as to produce eflicien-t combustion. 1

Having thus described my invention, what I desire to claim as new is:

1. In a'furnace wall, the combination of a series of tubes, clamps secured to said tubes and constructed to hold said tubes spaced from each other and in a definite positional relationship to each other, refractory blocks protecting said tubes and clamps, and additional means for securing said blocks to said tubes.

2. In a furnace wall, the combination of a series of tubes, clamps secured to said tubes and constructed to hold said tubes spaced from each other and in a definite positional relationship to each other, said clamps being spaced longitudinally of the tubes, each clamp comprising a bar havin a series of recesses to receive a plurality of a acent tubes, bolts extending through each bar and embracing said tubes and serving to draw them into said rccesses, and refractory blocks bearing against saidtubes between said clamps.

3. In a furnace wall, the combination of a seriesof upwardly extending tubes, clamps secured firmly to said tubes but spaced apart longitudinally of the tubes and serving'to hold the tubes in spaced relationship, each clamp comprising a bar having recesses to re ceive a plurality of ..djacent tubes and bolts embracing said tubes and serving to draw them into said recesses, certain of sald clamps being arranged in staggered relationship to others, and refractory blocks protecting said tubes between said clamps.

4. In a furnace wall, the combination of a series of upwardly extending tubes adapted to conduct a cooling fluid, a header to which said tubes are connected, a plurality of substantially horizontal clamps secured rigidly to said tubes and spaced apart longitudinally ofthe-tubes and serving to hold the tubes spaced from each other, and blocks of silicon carbide held in contact with said tubes between said clamps, the weight of said blocks being at least partly supported by the clamps.

5. In a furnace wall, the combination of a series of upwardly extending tubes, clamps secured firmly to said tubes but spaced apart.

longitudinally of the tubes and serving to hold the tubes in spaced relationship to each other, and refractory blocks bearing against said tubes between said clamps and protecting said tubes and clamps, the clamps supporting a substantial part of the weight of said blocks, and means independent of said clamps for holding said blocks in their operative relationship to said tubes.

6. In a furnace wall, the combination of a series of upwardly extending tubes; a plurality of clamps secured to said tubes and serving to hold the tubes in spaced relationship to each other; each clamp comprising a horizontal bar located. immediately beside said tubes but extending transversely to them andmeans for securing the tubes to said bar; and a series of refractory blocks located immediately above said clamps in protective relationship to said tubes.

'7. In a furnace wall, the combination of a series of upwardly extending tubes; a plurality of clamps secured to said tubes and serving to holdthe tubes in spaced relationship to each other; eachclamp comprising a hor1- zontal bar located immediately beside said tubes but extending transversely to them, U-bolts embracing said tubes, respectively, and having threaded shank portions extending through the bar, and nuts .on said shanks cooperating with the U-bolts to secure the tubes rigidly to the bar; and refractory blocks located immediately above said clamps in protective relationshi to said tubes.

HgWARD G. THAYER.

Images