US3445101A

US3445101A - Cooling units for fume hood on basic oxygen steelmaking furnace

Info

Publication number: US3445101A
Application number: US572403A
Authority: US
Inventors: June H Reighart
Original assignee: HOWARD M KOHN
Current assignee: HOWARD M KOHN
Priority date: 1966-08-15
Filing date: 1966-08-15
Publication date: 1969-05-20
Anticipated expiration: 1986-05-20
Also published as: CH483168A

Description

H. REIGHART 3,445,101 COOLING UNITS FOR FUME HOOD ON BASIC OXYGEN Filed Aug. 15, 1966 May 20, 1969 STEELIIAKING FURNACE Sheet mvzsmoa. JUNE n. REIGHART J. H. REIGHART 9 'rs FOR Fuus noon on BASIC OXYGEN May 20, 1969 3 445 101 COOLING UNI NTO JUNE IEIGNART [Maw 9- MM;

ATTORNEY Y My 20, 1969 J. H. REIGHART COOLING UNI TS FOR FUME HOOD ON BASIC OXYGEN STEELMAKING FURNACE Sheet Filed Aug. 15, 1966 INVENTOR. JUNE H. RE'BHART CU Am.

ATTORNEY y 20, 1969 .J. H. REIGHART 3,445,101

COOLING UNITS FOR FUME HOOD ON BASIC OXYGEN STEELMAKING FURNACE Sheet 4 of 8 Filed Aug. 15, 1966 INVENTOR. JUNE H. REIGHART ATTORNEY May 20, 1969 J. H. REIGHART 3,445,101 COOLING mans FOR FUME noon on BASIC OXYGEN STEELMAKING FURNACE Filed m. 15, 1966- Sheet mm 52 mQE ATTORNEY v y 20, 1969 J. H. REIGHART 3,445,101

COOLING UNITS FOR FUME HOOD ON BASIC OXYGEN STEELMAKING FURNACE Filed Aug. 15, 1966 Sheet 6 of a 7 1 INVENTOR.

F/g. 4 BY JUNE a. aslemm 6U Am ATTORNEY May 20, 1969 Filed Aug. 15, 1966 Fig. /5

J. H. REIGHART COOLING UNITS FOR FUME HOOD ON BASIC OXYGEN STEELMAKING FURNACE Sheet 7 of a I l l I I F ig. /5a

INVENTORV JUNE H. REIGHART ATTORNEY y 20, 1969 J. H. REIGHART 3, 5,

COOLING UNITS FOR FUME HOOD ON BASIC OXYGEN STEELMAKING FURNACE 8 Filed Aug. 15, 1966 1 Sheet of 8 v N o INVENTOR.

JUNE H. RElGl-IART ATTORNEY United States Patent 3 445,101 COOLING UNITS F0 R FUME HOOD 0N BASIC OXYGEN STEELMAKING FURNACE June H. Reighart, Cleveland, Ohio, assignor to Howard M. Kohn, trustee Filed Aug. 15, 1966, Ser. No. 572,403 Int. Cl. C21c 5/38 U.S. Cl. 266-16 4 Claims ABSTRACT OF THE DISCLOSURE The apparatus disclosed herein comprises water-cooled panels and fume hoods assembled therefrom for conducting hot gases from a furnace. These fume hoods comprise a plurality of internally cooled panels, each panel consisting of two spaced apart parallel metallic plates bent at their edges to form a longitudinal passageway, at least one of the plates being depressed longitudinally at spaced intervals toward the opposing plate so as to provide a plurality of substantially parallel longitudinally extending passageways in each panel. In addition to such depressions giving strength to the panel, the aforementioned depressions prevent crossfiow or angular flow through the panel and instead cause more uniform longitudinal flow in the interior of the panels. This avoidance of channeling in the flowing of cooling medium through the panel provides more uniform cooling of the panel and avoids overheating in any particular area around which or away from which the cooling medium might otherwise be directed. This more uniform cooling because of the subdivision of the panel into a plurality of longitudinal passageways effected by these longitudinal depressions avoids hot spots and failures in the panel caused thereby. Consequently the life of each panel is prolonged many times over the life of panels in which the flow of cooling medium is not so uniformly controlled.

This invention relates to water-cooled hoods for basic oxygen furnaces. More specifically it relates to watercooled sections or panels for assembly into fume hoods for basic oxygen furnaces. In the operation of a basic oxygen furnace for the production of steel, the charge of about 100250 tons of molten metal is refined by the impingement of a stream of oxygen downwardly onto and into the molten charge. The oxygen blow or impingement period lasts about 18-20 minutes, which is about one-half to one-third of the refinement cycle, or the period from furnace charge to furnace charge.

During the oxygen blow period, hot gases are emitted from the charge. In order to avoid loss of these gases and to avoid contamination of the atmosphere therewith, a fume hood assembled of individual panels or sections is arranged directly above and around the top of the furnace. This hood guides the emitted gases to a substantially vertical stack where they are cooled for ultimate disposition.

The gases released from the molten charge are at a temperature of approximately 3,000-3,500 F. Moreover, these gases usually contain suspended solids, such as iron oxides, which require separation by passage of the dust ladened gases through dust separating devices. Before the gases are introduced into these separators, they must be cooled considerably. The individual sections or panels from which the hood is assembled are water-cooled in order to protect the hood as well as to aid in cooling the gases. Due to high temperature and the velocity of the gases in contact with this hood, the water-cooled linings of the hood are subject to rapid deterioration and require frequent replacement.

Present designs of such fume hoods are illustrated in ice Patents Nos. 3,168,073, 3,197,186; and in Iron and Steel Engineer, April 1964, pp. 108-118.

Such hoods generally have an inside diameter of 15-20 feet and are assembled from a plurality of water-cooled panels. Since these panels are exposed to drastic temperature changes, in view of the extreme temperatures generated during the blow period and the considerably lower temperature reached during the non-blow period when the cooling water is still running through the interior of the panels, the metal of which these panels are constructed undergo considerable stress and strain due to this thermal shock, and also due to the strain imposed by having a hot side in contact with the emitted gases and a relatively cool side at the surface exposed to the cooling water and the atmosphere.

Moreover the fact that there is a considerable difference in temperature between the hot and cold sides of the panel means that there is greater expansion of the metal on the hot side. This produces a tendency for warping or vertical bending of the panel. Consequently these panels must have suflicient strength to withstand this bending. For this purpose present panels have supporting bars welded to the two faces on the inside of the panel to impart strength.

Furthermore, since these supporting bars which also serve to keep the hot and cold faces of these panels separated from each other and to divide the space between them into channels, the considerable amount of welded area causes variations in heat transfer rates which causes further strains in the metal in these panels.

As a result of these various stresses and strains imposed by the conditions described above, as well as the requirements imposed on the panels for supporting their own weight and the weight of the water flowing therethrough, the panels of the type presently in use become warped and distorted. These panels buckle after relatively short periods in operation and frequent replacement is necessitated. Consequently in addition to the cost of the replacement panels, the loss of production time during the replacement period represents a considerable increase in production cost. As a result improvements which will effect greater strength and longer life of these panels are very much to be desired.

In accordance with the practice of this invention, it has now been found that longer panel life and greater strength can be imparted to water-cooled panels suitable for assembly into the fume hoods of basic oxygen furnaces by the improved design described herein. In the various designs of panels described hereinafter strength is imparted to these panel faces by corrugations impressed therein. The improved strength imparted by these corrugations permit various improvements and advantages in panels not otherwise attainable, such as reversible panels, etc.

Since it is necessary to have replacement panels in storage and easily available for replacement of damaged panels, it is necessary to have a complete stock on hand of every panel in the assembled fume hood. A complete replacement stock is required since it is not known which of the various panels will be damaged. Moreover in view of the close fitting required of adjacent panels to prevent escape of gas or fumes between panels, it is necessary that a replacement panel should be of the identical dimensions as the panel being replaced. If it is at all practicable, it is desirable to have as many panels as possible of the identical configuration and dimensions so as to reduce the number of panels required to be kept in storage for replacement purposes. The improved design of this invention permits more duplication and thereby reduces the number of replacement panels that need to be stored.

A particular advantage of the panels of this invention is that it permits the design of panels which are reversible so that a particular face can be used as either the hot face or the cold face. These reversible panels can therefore be designed to be used in a number of positions in the assembled fume hood. Consequently a smaller number of panels need to be kept in storage as replacements. In such cases, the cutting of the openings and attachment of the water inlet and exit connectors is postponed until the panel is selected for a particular location in the fume hood. Also at this time attachment can be made of the supporting rods.

The improved panels of this invention are best described and illustrated by reference to the drawings.

FIG. 1 is a front elevational view of a fume hood showing the general assembly using panels of this invention.

FIG. 2 shows a side elevational view of this same fume hood.

FIG. 3 is a perspective view of a rectangular panel of this invention with the cold face of the panel being shown at the top of this view, showing also a broken cross-sectional view.

FIG. 4 shows a perspective view of this same panel inverted so that the hot face of the panel is shown at the top.

FIG. 5 shows an assembly view in perspective of two sheets of metal shaped to form the corrugated cold face and a smooth hot face respectively.

FIG. 6 shows in perspective another modification of the panel of this invention in which the lower dge f the panel is tapered or slanted.

FIG. 7 is another perspective view of the tapered panel of FIG. 6 inverted and showing the smooth hot face on top whereas the view in FIG. 6 has the cold face on top.

FIG. 8 shows a modification of the panel of this invention which is adapted to form and fit around the opening designed to receive the oxygen lance.

FIG. 9 is a perspective, partially broken view of a panel of the prior art which is included for comparative purpose.

FIG. 10 shows a cross-sectional transverse view of a panel of this invention in which a number of corrugations have been made in the hot face of the panel.

FIG. 11 is a crosssectional transverse view of another panel of this invention in which a number of corrugations have been made in the cold face of the panel.

FIG. 12 shows a transverse cross-section view of a reversible panel of this invention in which corrugations have been made in both the cold face and the hot face, and designed so that either face may be used as the cold face or hot face.

FIG. 13 shows in transverse cross-section a reversible panel of this invention in which corrugations are made in both the cold face and hot face, and designed so that either face may be used as the cold face or hot face.

FIG. 14 is a transverse cross-sectional view of another panel of this invention which is likewise reversible in that either face can be used as the cold face or hot face, and both faces have corrugations some of which are staggered from corrugations in the opposite face and other corrugations are opposite each other in the two faces.

FIGS. 15 and 15a each show a single sheet of steel plate cut in an outer configuration so that the two sheets can be shaped and combined to form a rectangular panel of this invention. Triangular notches are cut into sheets to accommodate the formation of corrugations in the surface of the sheet, which corrugations which will eventually appear in the hot and cold faces of the resultant panel.

FIG. 16 shows a perspective view, including a broken cross-sectional view, of the resultant panel corrugated, shaped and welded from the two sheets shown in FIGS. 15 and 15a.

The expression corrugation or corrugations is used herein to describe linear indentations or grooves in the face plates of the panels of this invention. While the expression corrugations is generally used to refer to a continuous wavy surface having alternate ridges and furrows or crests and valleys of approximately equal rise and fall, the expression is used herein to denote linear indentations or valleys or grooves impressed in only one direction into the otherwise flat surface of the respective faces. Thus corrugation refers to the linear indentation groove or valley which is made to extend inwardly from the surface of the hot face or cold face toward the channel formed between the two faces. These corrugations can be either rolled or formed.

Corrugated water-cooled hollow sections are known as shown in Patents Nos. 2,956,552 and 2,919,683. However, the hollow sections disclosed in those patents are distinctly dissimilar from the novel panels disclosed in this application and are for an entirely different use and purpos Moreover the corrugations of the prior art do not serve the dual function as in the present invention of strengthening the panel and channeling the cooling medium.

In order to produce a sufiicient increase in strength, it is desirable in the present invention that the corrugation extend a sufficient depth into the space between the two faces. This depth will range from that desired to give the minimum increase in strength desired to the maximum possible distance, which is the full distance between the two faces, and which maximum will vary obviously according to variations in the spacing of the two plates. In any case it is preferable to have the corrugation extend at least a distance twice the thickness of the plate, or in most cases a distance of at least /2 inch.

Furthermore, the number of corrugations and the spacing between corrugations in a particular face will depend upon the desired increase in strength and also whether there are to be any stay'bolts used. The increased strength desired depends somewhat upon the temperature shock to be withstood, the number of corrugations required being correspondingly increased with the greater severity of thermal shock to which the panels will be exposed. Here again this is determined somewhat by the specific location of the panels in the assembled fume hood.

The depth or thickness of the channel between the two faces, or in other words, the distance between the hot and cold faces, will vary depending on whether it is desirable to have a high or low flow velocity through the channel. With a low velocity of fluid flow, it is preferable to have a channel thickness of about 1-2 inches. With high velocity fluid flow, this thickness can be even less than 1 inch. The width of the panels is generally in the range of 2-4 feet, again depending upon the particular location and other conditions.

As previously stated, the length of the panels is generally in the range of 14-21 feet depending upon the particular location in which a panel is to be used, and the length can vary even beyond this range, again depending upon the particular location and use of the panel. The thickness of the steel plate used in making the panels is preferably /4-% inch.

The number of corrugations determines the number of subchannels or ducts for the cooling medium. However, as shown in the panel structure of FIG. 5, additional subchannels can be provided by the use of fins 25 in addition to the corrugations.

It is necessary to have the main channel area in the panels subdivided into sub-channels or individual channels to insure uniform cooling of the hot face 'by more uniform flow of the cooling medium through the main channel area. Where such subdivision into individual channels is not provided there is the likelihood that the cooling liquid will flow faster in certain areas and flow slower in other areas. This will result in uneven cooling of the hot face and very often there are regions in which there is practically no flow of cooling medium. Not only does this reduce the efliciency in cooling the hot gases, but there are greater strains and stresses placed on the metal in these panels.

The fins used in some cases to divide the main channel into additional sub-channels are there primarily for this purpose and are not used to give support or strength to the two faces. Generally these are spot-welded to the faces only at various points along the length thereof. In some prior art instances, as illustrated in FIG. 9, these fins have lateral projects which extend into slots cut in the faces and these lateral extensions are then welded to the respective faces. In such cases, these extended, Welded fins are regarded as a substitute for a certain number of staybolts. The use of staybolts and extended fin substitutes as described above require a considerable amount of welding which, as pointed out herein, causes variations in heat transfer and accompanying problems.

In the present invention, the use of staybolts can be dispensed with entirely by using a greater number of corrugations. Where desired, the corrugations in one face can be made to abut corrugations in the opposite face. In such cases, or where the corrugations extend into contact with the inside surface of the opposite face, spotwelding in such contacting areas between the two faces can be performed at a sufficient number of points to give sufficient rigidity and strength as to permit dispensing completely with the staybolts. Where staybolts are to be dispensed with entirely, it is desirable to have corrugations at least about every 6 inches through the width of at least one face. Where staybolts are to be used it is desirable to have at least one corrugation per each 12 inches of the width of a face.

The hot face of the panel is advantageously smooth so as to avoid the build-up of slag particles and thereby a layer of slag on the surface of the panel. These panels are advantageously fabricated from one or two sheets of steel of appropriate thickness and other dimensions to be shaped into the desired configuration.

As previously stated one of the most important features of the panels of this invention is the corrugated structure of one or both faces of the panel, thereby imparting sufficient strength to the panel to withstand the buckling and other strain to which the panel is exposed as described above. These corrugations are of sufficient number to reduce the necessity for supporting bars or staybolts as described above, and in fact with sufiicient corrugations the use of staybolts and supporting bars can be dispensed with entirely.

When corrugations are placed in both faces of the panel, the corrugations in one face can be either directly opposite or staggered in relationship to the corrugations in the other face. The depth or the crest of the corrugations can be sufficient as to cause contact between the two plates or can be of a lesser dimension so as to avoid actual contact between the faces. The strength imparted to the respective faces is primarily inherent in the corrugations itself and not from the actual contact where such contact exists. In fact it is sometimes desirable to avoid actual contact between the corrugations and the faces, and thereby allow flow of water therebetween in order to prevent deposits from accumulating. Such accumulations decrease the heat transfer from the metal to the circulating water and thereby reduce the efficiency of cooling.

The flow of cooling water is channeled between adjacent corrugations running the length of the panel faces. Even where the corrugations do not come into actual contact with the opposite face, this channeling is effected since the restricted space between the particular corrugations and the opposite face minimizes flow between channels. Even where the respective corrugations are in actual contact with the opposite face, it is desirable to have the corrugation at the respective ends turned away from the opposite face so as to be out of contact for at least a short distance. This permits water to flow between the corrugation and the opposite face and to minimize deposition at these points.

At each end of the panel there is a header or manifold adapted to feed or exit water into or from the respective channels formed between corrugations, or between corrugations and separator bars. Additional strength can be given to the panels by having at each longitudinal edge a section of greater overall thickness than through the two faces, and adapted to have water flow through the longitudinal channel thus formed at the two edges.

In a preferred embodiment of this invention, the panels generally have dimensions of 14-21 feet in length and 2-4 feet in width. With the corrugations described herein, and with or without separator fins or bars, it is found that panels of desired strength can be fabricated from steel sheets having a thickness of preferably about inch. As shown in FIG. 5, a panel of this invention can be fabricated from two sheets of steel, one sheet forming the hot face of the panel and having the terminal ends folded upward to form a part of the header or manifold, and also having the lateral edges turned upward, with a second turn effected to form the top of the longitudinal channels running the length of the ultimate panel.

The cold face of the panel is advantageously fabricated from a second sheet of steel having a plurality of the corrugations described herein, and also having the two longitudinal edges turned upward so as eventually to join with the longitudinal turned edges of the first sheet of steel as described above.

This second sheet of steel bearing the corrugations also has a number of holes (not shown) drilled therein into which staybolts are inserted and welded. These staybolts are welded to both the cold face plate and the hot face plate to keep the two plates separated from each other and to give rigidity. However, the use of these staybolts and the separator rods described above are optional and by use of a suflicient number of the corrugations described herein, the staybolts and spaced rods can both be dispensed with. In such case, it is generally advantageous to have a number of points along the corrugations spot welded to the opposite plate and thereby to impart greater rigidity to the assembled panel.

In the embodiment described above, the strength of the panel against vertical bending is derived primarily from the combination of the corrugations and the lateral chaunel-forming edges. If staybolts and separating strips or rods are used, a minimum of 2 corrugations is generally satisfactory for a panel of about 2 feet width. However, where it is desired to avoid the use of staybolts or separating strips, or both, a greater number of corrugations are used and in such cases, at least 3, preferably at least 5 corrugations, are advantageously used, either in one face or in the combination of both faces. Avoiding the use of staybolts and separating strips in the manner described above, advantageously minimizes the amount of welded areas and also minimizes the nonuniformity of heat transfer and strains produced by the large number of welded areas present in prior art panels.

The headers or manifolds can be fabricated by having the two terminal turned-over pieces of sufiicient width to permit second and third turns as to form the entire channel of the header or manifold. Generally however, it is more convenient to use another piece of steel of the same thickness and of sufficient width to form the top and side of the header channel by welding to the edge of the turned over terminal pieces shown as 21 in FIG. 5. The shape and contour of the third side (shown as 23') of this header channel-forming member is such as to permit fiow of water from the manifold into the various channels running the length of the panel. The lateral edges 23 of the cold face plate are also Welded to the lateral edge of the hot face plate which has been turned over and shaped to form the top 20 and sidewall 19 of the lateral channels as shown in FIG. 5.

Most of the panels used in assembling the fume hoods have a rectangular shape as shown in FIGS. 3, 4 and 5. However, in order to accommodate and to form the flared out sections shown at the bottom of the hood, various shapes other than rectangular are desired. For example, FIGS. 6 and 7 show a panel having a rectangular overall configuration on three sides and the fourth side is angular. Obviously a number of panels of this configuration having different overall lengths will be necessary in order to form the taper desired in the skirt or lower edges of the hood. Other Shapes such as truncated triangles, parallelograms, etc. are also possible. For example, in certain cases the panel will have only a slight tapering from a true rectangular configuration and will resemble more truely a truncated triangle with slightly larger base than top. In other cases, the panels will have a shape designed to encircle the opening through which the oxygen lance is inserted to the top of the furnace. Such a configuration is shown in FIG. 8.

These panels from which the fume hoods are assembled are suspended into position and are supported by means of a number of suspension bars extending from the cold face plate of the panel as shown in FIGS. 3 and 6. In order to avoid confusing the various illustrations, the hooks and supporting means therefor are omitted from the drawings. However these hooks and supporting means are similar to those used for this purpose with prior panels.

The cooling water is admitted to and exited from the respective inlet and outlet manifolds by means of connectors welded to the respective manifolds. Once the plates are assembled into position, flexible inlet and outlet pipes or tubes are connected to these connectors. The panels are suspended and supported into position as described above and are placed in abutting close contact with adjacent panels as to restrict the flow of gas or fumes therebetween. Since the panels need to be periodically replaced, some more frequently than others, the panels are advantageously not welded to each other.

By having the stack into which the hot gases are fed of sufficient height and under such low pressure as to cause the gases to be swept upward, there is not suflicient pressure as to cause any great leakage of these gases between the respective panels.

In certain areas or positions adjacent to the assembled fume hood, there may be certain obstructions which interfer with access to the connectors feeding water into the interior of the panel. In such cases a connecting channel is fabricated on the exterior of the cold face plate so that the connector may be located at a more convenient position on the cold face plate. This is shown in FIG. 6 where channel 26 is connected to the lower manifold 8 in such a manner that the connector can be positioned toward the middle of the cold face plate. In such case a drainage opening 24 is advantageously located in the lower manifold.

The configuration of the hood can take various designs depending upon the particular location of the basic oxygen furnace, the adjoining equipment and the stack to which the hot gases are to be fed from the fume hood. Generally, the bottom region of the hood is flared outwardly to embrace a greater horizontal area immediately above the opening of the furnace. Then the cross-section of the hood is narrowed progressively through a certain portion of the height until an appropriate reduction in cross-sectional area is achieved and from there the remaining height of the hood has a uniform cross-section.

Depending on the particular location of the stack into which the fumes are to be fed from the hood, the linear axis of the hood can be slanted or vertical. If the stack is immediately above the hood, the linear axis of the hood is vertical. If the stack is located behind or to one side of the furnace, the linear axis of the hood is slanted from the vertical. If the layout shown by FIGS. 1 and 2, the stack is located immediately above the furnace, and therefore the rise of the hood is substantially vertical. In this particular design of FIG. 1, the hood flares out to a greater extent in the front namely in that direction towards which the furnace is tilted for emptying and there is less flare at the two sides and at the back of the lower portion of the hood. Then the lower portion tapers inwardly to the upper region of the hood which is substantially uniform and square in cross-section for the remaining height of the hood. While the overall transverse crosssection of the hood is generally square or rectangular, it can also be circular, in which case the faces of the plate are curved with corrugations in one or both faces.

In the front flared out portion in the lower region of the hood there is an opening through which the oxygen lance can be lowered and introduced vertically into the furnace. This permits a stream of oxygen to be directed downwardly onto and into the molten metal in the furnace. The opening in the hood through which the lance is introduced, is constructed by having a number of panels especially shaped, as shown in FIG. 8.

FIG. 1 shows a front elevational view of a fume hood 1 assembled from panels of this invention. The fume hood is positioned over a basic oxygen furnace 3 shown in phantom view and is connected at the top to a stack 4 (also shown in phantom view) through which the fumes pass on their way to a dust separator and other recovery or separating equipment. FIG. 1 shows the opening 5 through which the oxygen lance (not shown) is passed vertically downward into the basic oxygen furnace. Panels 2' are modifications of the panels of this invention adapted to fit around the opening 5. The panels in the upper two sections of the fume hood are rectangular in configuration whereas the panels in the flared out portion 1 at the base of the fume hood are especially shaped to accommodate this flaring.

FIG. 2 shows a side elevational view of this same fume hood showing a greater flare in the lower section at the front of this hood, again with the individual panels having a shape designed to accommodate this flare.

FIGS. 3 and 4 show different views of the same typical rectangular panel of this invention. Facing upward in FIG. 3 is the cold face 6 which has a number of corrugations or grooves. As shown in the broken transverse crosssection and in other views, these corrugations are curved in cross-section so that in a top view the lines delineating the grooves and flat surfaces of the cold face of the panel are exaggerated for illustrative purposes. The manifolds or

headers

8 and 9 are at opposite ends of the panel and communicate with each of the individual channels running linearly from one end of the panel to the other. Connector 10 is fastened to manifold 8 positioned at an opening in manifold 8 so that water fed into connector 10 will flow into manifold 8 and eventually through the channels between the two faces. This water, after traveling the length of the channels, will pass through exit manifold 9 and out exit 11 which is likewise positioned over an opening in and attached to manifold 9. Supporting bars 12 are fastened to the cold face by means of supporting flanges 13. In this modification, raised edge portions 14 form, in conjunction with lateral sides 15, a deeper channel running the entire length of the panel from inlet manifold 8 through outlet manifold 9. Lateral sides 15 are also referred to as side walls or side plates. They are preferably integral with either or both the hot and cold face plates as shown in the drawings, in which case they are formed by bending the hot or cold face plate through an angle of In the reverse view shown of this same panel in FIG. 4, the top rectangular surface 16 is the hot face of this panel. In this particular modification this is a smooth surface having no corrugations.

FIG. 5 illustrates how a rectangular panel of this invention can be assembled from two pieces shaped and fabricated from two sheets of steel. One sheet is used to fabricate the lower portion 17, with the main part of the sheet forming the flat surface 18 and constituting the hot face 16 of the ultimate panel. The lateral edges of this sheet have been turned upward 90 to form the lateral edges or side walls 15 of the panel and these lateral edges have been turned another 90 to form the top of the raised portions 20 which ultimately will form in part the two channels running the length of the panel and along each side thereof. At each end, the edge portion of the sheet is turned upward to form the side 21 which will eventually form one side of the manifold 8 shown in other views. The top and opposite side of this manifold (not shown in this view) is separately fabricated and fitted.

The second sheet of steel is cut to proper dimensions and shaped as shown by piece 22 which is lowered into the interior of the fabricated piece 17. Fabricated piece 22 has its lateral edges 23 turned upward 90 from the main body of the sheet and When inserted into position in the interior of 17 these turned up lateral edges 23 form the interior wall of the raised channel shown in other views. The fabricated piece 22 has two corrugations 7 pressed into and running the entire length of the sheet. This fabricated piece 22 also has three fins 25 running the length of the sheet and spot-welded to the underside of the fabricated sheet 22 at a number of points. Pins 25 are attached for the purpose of dividing the main channel between cold face 6 and hot face 1 6 into a number of subchannels. Corrugations 7 also serve to divide this space into channels. In some cases it is desired to dispense entirely with fins 25 and to have a greater number of corrugations to subdivide the main channel into the desired number of subchannels.

FIG. 6 shows another modification of the panel of this invention in which the lower end or manifold portion 8' is slanted. In this view the connector 10 for feeding water into the manifold formed by slanted end 8 is not located at the manifold but is connected to a channel 26 which is in turn connected to the manifold. This spacing between connector 20 and the manifold at the slanted end 8 is sometimes necessitated by the fact that the positioning of this panel in the assembling of the fume hood is in a location where there is not space to accommodate the connector 10 at the lower end of the panel. In this type of arrangement it is desirable to have a drainage plug 24 located in the manifold at the lower end of the panel.

FIG. 7 is a view of the opposite side of the panel shown in FIG. 6 having the lower slanted edge 8'. This view has the hot face 16 facing upward.

FIG. 8 shows a modification of the panel of this invention adapted to fit around the opening in the front flared out portion of the fume hood through which the oxygen lance is lowered into the basic oxygen furnace. This modification shows how the configuration is adapted to fit around the opening. By having the upper and lower parts of this panel of greater Width than that part which will be horizontal with the opening, it is possible after the positioning of a number of such panels to continue the assembly with panels having parallel sides as shown in FIG. 1. In the configuration of FIG. 8, there are three corrugations 7 running the length of the panel and dividing the main channel between the hot and cold face into a number of sub-channels. The broken section at the left end of the panel shows how the two channels at the two linear sides of the panel are of greater height and are formed by

side walls

15 and 23 as well as top section 14. These channel forming members in this type of structure contribute to increased strength in the panel.

FIG. 9 illustrates a typical prior art panel and is included to illustrate various advantages of the panel of this invention. In this prior art panel of FIG. 9, one sheet is used to form the hot face 16 and the sides 15. However, a number of individual strips 6 are used to make up the cold face. These cold face strips 6 are separated from each other by fins or dividers 27 which are of different heights as shown in the drawing. Dividers 27' have projections 27" which extend through slots in the strips 6'. These projections are welded 28' to the top of strips 6' and serve as substitutes for staybolts. These dividers in addition to supporting the cold face strips 6' and keeping them separated from hot face 16, serve to divide the space between the hot and cold faces into separate channels. Each of these dividers is welded at the bottom to plate 16 at the top to plates 6'. The welded areas 28 run the entire length of the faces. Also, end closure plate 9 is welded to each of the abutting ends of dividers 27.

From the number and extensiveness of such welded areas, it is obvious that there is a consider-able amount of fabrication work required in assembling a panel of this type. Moreover, the welding effects a change in the physical characteristics of the steel which in turn affects the heat transfer characteristics of the steel. Consequently the excessive amount of welded areas required in prior art panels, as shown in FIG. 9, results in unevenness in the distribution of heat and non-uniformity of temperature in such panels.

The excessive welded areas result in greater strain and warping of the panels because of the repeated heatingcooling cycles with resultant cracks and separation of panel elements, thereby requiring more frequent replacements. These disadvantages are avoided in the panels of the present invention which, as shown in various drawings, require much less welding.

The transverse cross-sectional view shown in FIGS. 10l4 illustrate various possible arrangements of corrugations in either or both the cold and hot faces and also staggered and opposing arrangements of the corrugations and combinations thereof. These are advantageously fabricated from two corrugated sheets joined by the welded areas 28.

For example, FIG. 10 shows three corrugations in the hot face and none in the cold face, with a raised lateral edge channel-forming member which gives added strength to the panel.

FIG. 11 shows 3 corrugations in the cold face whereas FIG. 12 shows a combination of 2 corrugations in the cold face and 3 in the hot face.

FIG. 12 shows a reversible panel having corrugations in both faces and having the longitudinal edges forming the longitudinal edge channels centered with respect to the depth of the main channel so that they protrude an equal distance in both the hot and cold faces. Moreover, each of the walls 23 forming these longitudinal edge channels are gradually sloped so as to avoid causing turbulence in the gases which flow along whichever face is used as the hot face. Furthermore, wall 23' (not shown in this view) which forms a part of the header or manifold is likewise gradually sloped for the same purpose, advantageously about FIG. 13 illustrates a reversible panel having 4 corrugations in both faces 30 and 30' either of which can be used as the hot face or the cold face.

FIG. 14 illustrates another reversible panel having 3 corrugations in one

face

30 and 4 corrugations in the other face 30', the corrugations closest to the lateral edges being opposite each other whereas the corrugations farther removed from the lateral edges are staggered. By a suflicient number of corrugations, it is possible to impart sufficient strength to these reversible panels to avoid buckling or lateral bending.

While FIGS. 2-14 show the various corrugations as not touching the opposing face, it is desirable where it is intended to dispense entirely with the use of staybolts, to have the corrugations touch the interior of the opposite face or be in contact with corrugations in the opposing face. Then by spot-welding along the corrugations, it is possible to impart sufiicient rigidity to the panels to avoid entirely any need for staybolts.

While staybolts can be used in the panels of this invention, they are not shown in the drawings since such details would confuse the structures being depicted as the patentable features of this invention. However, these staybolts are of the type and location used in prior art panels. In most cases, holes of appropriate size and location are drilled in the cold face and staybolts are gunned into the holes and welded to the cold face and eventually also spotwelded to the hot face. Since their use in the panels of this invention is entirely optional and the manner of using 1 1 them is similar to that in the prior art, they have been omitted from the drawings.

If desired, it is possible with such reversible panels as shown in FIGS. 13 and 14, to fabricate the faces and the headers from the same sheets of metal so that there is a very minimum of welding required. In such case, only the welding of the lateral edges of this single sheet and the shaped section which forms the manifold is required.

The use of two sheets for this purpose is illustrated by FIGS. 15 and 16. Corrugations are produced in this sheet by first cutting pieces out from each end of the sheet as shown by

lines

31 and 43 in FIGS. 15 and 15a, and then rolling or pressing along the broken lines shown between respective points at which lines 31 meet, so that a linear indentation or corrugation is produced lengthwise in the sheet and reaching from one such point to the corresponding point at the other end of the sheet. This pressing of the sheet to form these corrugations causes each pair of lines 43 to come together or abut. By welding these edges 43 of these cutout sections,

manifold sections

8 and 9 are partially formed with a number of welded areas 43 in their surfaces. A rectangular sheet 35 can be used to form each of these end walls, having its edges welded with edges and 41.

The openings left at the peak of these cutaway sections are filled by any appropriate means to provide a slope of less than to gas travelling linearly at the deepest part of the corrugation. The surfaces of these filled areas are sloped gradually so that whichever of these faces is used as the hot face, the hot gases traveling along such corrugations will not hit a sharp angle at the end of the corrugation. This gentle slope avoids causing any eddies or turbulence in the gas flow. For this reason the angle between the line running along the base or valley of the corrugation will advantageously rise no more than 45 at the surface of the filled-in end of the corrugation.

In forming the panel of FIG. 16 from the two sheets of FIGS. 15 and 15a, the metal sheet of FIG. 15 is turned at a 90 angle at each of the dotted

lines

33 and 34. Then the sheet of FIG. 15a is positioned as the opposite face so as to form, together with end pieces 35, the panel shown in FIG. 16. The

lateral abutting edges

37 and 38 are welded. Also edges 40 and 41 are welded with the respective abutting

edges

39 and 42 of the end plate 35. In each case the welded area is shown by heavy weld line 28. It can be seen that the two faces of the resultant panel are substantially identical and therefore either face can be used as the hot face or the cold face. Accordingly the openings for the water inlet and water exit attachments, and also the supporting bars can be made or attached on whichever side is selected as the cold face for the panel.

In the event the sheet shown in FIG. 15a is not to be corrugated (in other words having only the opposite face of the panel corrugated), it is possible to dispense with separate end pieces 35 by having the sheet of FIG. 15a extend a corresponding distance at each end so that a 90 bend at the respective ends will furnish the end sides for completing the header or manifold structures.

In addition to the added strength imparted by the corrugations, as described herein, an important feature of this invention is the fact that the designs permitted by this invention require much less welding. In view of the considerable reduction in welded areas, as compared to prior art panels, this invention avoids many of the disadvantages of prior art panels, particularly as discussed above in connection with FIG. 9.

Thus the corrugations do the multiple job of adding strength, forming defined water channels and eliminating much of the welding that was previously required. Another important feature of the panels of this invention is the fact that, where desired, added strength can be given to the panels by the use of water-cooled side rails 12 as illustrated in FIGS. 3, 5, 6 and 8. These show such side rails formed as a greater thickness of the panel at the longitudinal edges thereof.

While certain features of this invention have been described in detail with respect to various embodiments thereof, it will, of course, be apparent that other modifications can be made within the spirit and scope of this invention and it is not intended to limit the inventon to the exact detals shown above except insofar as they are defined in the following claims:

The invention claimed is:

1. A substantially vertically disposed fume hood defining an enclosed stacklike opening above a furnace:

(a) comprising a plurality of internally cooled panels;

(b) each panel consisting of two spaced-apart parallel continuous metallic plates bent and welded at their edges to form a cavity; 7

(c) at least one of said plates having relatively deep inward depressions at spaced intervals towards the opposing plate to provide a plurality of substantially parallel longitudinally extending passageways in each panel;

(d) manifold headers extending transversely across the entire ends of each panel to provide cooling medium uniformly to, through and from each passageway; and

(e) means connected to the headers to provide cooling medium to and from the headers of each panel in an amount suflicient to uniformly withdraw heat from the overall faces of all panels intern-ally positioned in the stackline opening.

2. The fume hood of claim 1 in which the said plates externally positioned in the stackline opening have said inward depressions.

3. The fume hood of claim 2 in which the said plates being integrally positioned in the stackline opening also have said inward depressions.

4. A panel adapted for internal cooling and adapted for mounting in the assembly of a fume hood defining an enclosed stacklike opening above a furnace comprismg:

(a) two spaced-apart parallel continuous metallic plates bent and welded at their edges to form a cavity;

(b) at least one of said plates having relatively deep inward depressions at spaced intervals towards the opposing plate to provide a plurality of substantially parallel longitudinally extending passageways in each panel, said depressions extending into said cavity sufiiciently to induce longitudinal flow of the cooling medium in each passageway of the panel;

(c) manifold headers extending transversely across the entire ends of each panel to provide cooling medium uniformly to, through and from each passageway; and

(d) means conected to the headers to provide cooling medium to and from the headers in an amount sufficient to uniformly withdraw heat from the overall faces of the panel.

References Cited UNITED STATES PATENTS 1,943,855 1/1934 Carter -170 X FOREIGN PATENTS 69,899 1/ 1914 Switzerland. 36,013 5/1926 Denmark. 576,251 4/1958 Italy.

I. SPENCER OVERHOLSER, Primary Examiner. ROBERT D. BALDWIN, Assistant Examiner.

U.S. Cl. X.R. 165-17O