US2269478A - Apparatus and method for variable control of air supply and the like - Google Patents

Description

2 Shee'ts-Sheet l H. A. REECE Filed Jan. 7, 1941 Jan. 13, 1942.

APPARATUS AND METHOD FOR VARIABLE CONTROL OF AIR SUPPLY AND THE LIKE 44 INVENTOR.

BY AIYZBMABEHE. M WW H. A. REECE 2,269,478

APPARATUS AND METHOD FOR VARIABLE CONTROL OF AIR SUPPLY AND THE LIKE Jan. 13, 1942.

Filed Jan. 7, 1941 2 Sheets-Sheet 2 lillilili 9.

INVENTOR. IZ ERBEBTAIEEQ'E. BY WW m/w 4 a a L4 0 M of 0 4 @N/ H4. v 1.1.; 1. 5 1 a fig 1A a Q (Q o 1 a %U\ ww /NW Q NW/,3 W5 1 m mm o 1.100 M W 4L E hm f0 w w Patented Jan. 13, 1942 APPARATUS AND METHOD FOR. VARIABLE CONTROL or AIR SUPPLY AND THE LIKE Herbert A. Reece, Cleveland Heights, Ohio, assignor to Meehanite Metal Corporation, a corporation of Tennessee Application January 7, 1941, Serial No. 373,482

10 Claims.

My invention relates to supply apparatus for delivery of air and the like, such as wind boxes for metallurgical furnaces, and to the operation of the same.

My present invention, herein described, is related in general subject matter to my invention described in my United States Letters Patent No. 2,197,947 issued on April 23, 1940, and is directed to the same and similar problems of furnace operation and control of air flow as is set forth in said Letters Patent and also to the meeting of objects herein set forth.

In the following discussion and description the operation and structure of a cupola for the remelting of metal will be referred to but it is to be understood that my invention includes the structure and operation of all furnaces or similar devices wherein a blast of air or other gases is supplied through a plurality of tuyres or like openings to the interior of the furnace or similar device.

It is an object of my invention to provide a wind box for supplying an air blast at substantially equal velocities to each of a plurality of tuyres.

A further object is the provision of'improved apparatus for supplying an air blast to each of several tuyres at desired velocities without disturbing the relative volume of air supplied to each of the several tuyres.

Another object is the control of the air blast delivered to a plurality of tuyres of a furnace from a wind box.

Another object is the modification of the current of air blast moving through a wind box.

Another object is the modification of the direction of portions of an air blast passing through a wind box from an inlet to a plurality of outlets.

Another object is the provision of apparatus and method of modifying a flow of air through a common distributing chamber.

Another object is the provision of a device for improving the control of the air blast to a furnace. 1

Another object is the provision for the control of the melting zone of a furnace.

Another object is the provision for passing the air blast in a wind box through separate courses and for selectively opening and closing said courses to modify the flow of air through the wind box.

Another object is the provision for optionally shutting off the fiow of air through portions of the wind box to variably fix the modification of the flow of air.

Another object is the provision for selectively closing and opening opposite ends of adjacent courses through which the air flows through a wind box to facilitate the control of said flow of am Another object is the provision for dividing the wind box into separate courses and for controlling the flow of air therethrough.

Another object is the provision of closures for ends of said courses shaped to guide the flow of air past said closures.

Another object is the provision for adjustably moving air-flow control means longitudinally of the wind box to meet the particular requirements of the furnace.

Another object is the provision for positioning an air control device in a wind box in accordance with the dimensions of the furnace and its requirements.

Another object is the provision for providing an improved apparatus for satisfying the above desired objects.

Another object is the provision of an improved method for the attainment of the stated desired results.

Another object is the provision of a method for improved operation of a furnace and the supplying of air thereto.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure 1 is an elevational view of a wind box mounted upon a cupola;

Figure 2 is a cross-sectional viewvtaken lengthwise of the cupola and wind box shown in Figure 1, and is taken through the line 2-2 of Figure 4;

Figure 3 is a transverse cross-sectional view taken through the line 3-3 of Figure 2;

Figure 4 is a transverse cross-sectional view of the cupola and wind box taken through the line 4-4 of Figure 2;

Figure 5 is an enlarged sectional view taken through the line 5-5 of Figure 4 and shows one of the lower closures of my device in lowered position;

Figure 6 is a view similar to that of Figure 5 and shows the same closure in raised position;

Figure 7 is an enlarged detailed view of the wind box through the line 1-1 of Figure 4 and shows an upper closure of my device in lowered position;

Figure 8 is a view similar to that of Figure 7 and shows the same closure in raised position;

Figure 9 is an enlarged sectional view showing the detail of the raising and lowering means used for changing the position of my air control device within the wind box;

Figure 10 is a perspective view of one of the peaked closures utilized in my device; and

Figure 11 is adiagrammatical view of a wind box embodying the features of my present invention and illustrates the wind box opened up and lying in the flat so as to demonstrate one optional arrangement of the relative positioning of the parts and their cooperation.

Inasmuch as the invention disclosed herein is directed to the wind box and the portion of the cupola adjacent thereto it has not been considered necessary to show all parts of the cupola and therefore the drawings do not include the top portion and the bottom portion of the cupola, which portions may be considered as having the usual form. Also, for purposes of simplicity in illustration, the usual tap hole and slag hole are not shown. It has also been considered unnecessary to illustrate such other openings as a cleanout door, breast arch, or drop-bottom doors. The cupola with which the invention is associated and which is described herein may be considered, however, as having all of the parts necessary for the usual operation of the same.

As shown in the several views of the drawings the cupola body or shell 2| is in the form of a cylindrical shaft, the inner walls of the cupola body 2| being lined by the fire brick lining 24. The body 2| and the lining 24 are mounted upon the usual bottom plate and thereby forming the enclosed shaft of the cupola.

A wind box 22 of cylindrical shape is mounted 1 upon the cupola body 2| by welding or other suitable means and in the embodiment shown, the outer wall of the cupola body forms one of the enclosing walls of the wind box 22. It is therefore seen from the views of the drawings that the wind box 22 forms an enclosed jacket surrounding the cupola body 2| in such a way that air introduced into the wind box may circulate entirely around the cupola body.

The inlet conduit 23 is in communication with the air blower or other source of an air blast (not shown) and the inlet conduit 23 is connected to the wind box 22 at the upper portion of the wind box 22 so as to afford communication between the air blower and the inlet opening 25 of the wind box 22.

'In the cupola illustrated there are six tuyeres extending through the wall and lining of the cupola body 2| to establish communication between the interior of the shaft of the cupola and the wind box 22. Tuyeres 30, 3| and 32 as seen from the inside of the shaft of the cupola are illustrated in Figure 2. All six tuyres 30, 3|, 32, 33, 34 and 35 are shown in dotted lines in Figure 4. These tuyres are of substantially equal size and are uniformly spaced around the periphery of the cupola. It is to be noted that the tuyres enter the cupola body at a low level in the cupola and communicate with the wind box in a lower portion thereof. In order that the operator may look into the tuyres from the outside of the furnace, peep holes are provided in the wind box opposite each of the tuyres and mica or other suitable substance is sealed over these peep hopes. Except when necessary, peep hole covers 28 hingedly connected to the wind box 22 are kept in position over the peep holes by means of the latch members 28.

Vertically mounted within the wind box 22. intermediate the inlet 25 and the entrances to the plurality of tuyres, are a plurality of partition walls arranged to divide the cross-sectional area of the wind box into a plurality of vertical courses or sections. The arcuate partition walls 39 extend around the wind box and in slidable engagement with the inner and outer walls of the wind box. Radial partition walls 38 welded or otherwise suitably secured to the arcuate partition walls 39 extend across between the inner and outer arcuate partition walls 39. The radial vertical partition walls 38 are substantially equally spaced apart and extend substantially radially of the axial center of the furnace and thus divide the wind box at the location of these partition walls into a plurality of courses or sections with open ends of substantially equal size. The courses thus defined are substantially parallel and extend longitudinally of the wind box in the path of the flow of air from the inlet to the outlets. As the air must flow downwardly through these courses passing towards the tuyres any tangential or circulatory movement of the air flow is broken up by the confining walls of these courses and the flow of air reaching the tuyere entrances is modified by passing through these vertical courses.

It is seen that the arcuate partition walls 35 and the radial partition walls 38 thus assembled and joined together form a casing unit which is generally designated by the reference character 40. The unit 40 while snugly fitting within the wind box is so mounted that it may be moved upwardly or downwardly to change its position relative to the level of the tuyere entrances.

A plurality of closures l3 and 44 are provided for closing each of the several courses or sections of the unit 40. The closures are mounted at opposite ends of adjacent courses or sections iii) in such a way as to provide means for closin alternate courses or sections at the top and alternate courses or sections at the bottom thereby enlarging or diminishing the efiectlve cross-sectional area of the wind box. By selectively closing off courses in desired number the effective size of the wind box may be obtained to meet different conditions and requirements, such as when the internal diameter of the furnace shaft has been changed in the re-building of the furnace. The upper closures 43 are positioned adjacent the upper ends of alternate courses or sections of the unit 40 and the lower closures 44 are positioned adjacent the lower ends of other alternate courses or sections of the unit. The closures l3 and H are peaked to provide downwardly sloping sides and are thus inclined in a longitudinal direction toward the outlets to the tuyeres. By having the closures at opposite ends of adjacent courses or sections of the unit it is possible to have the closures for adjacent courses or sections both raised or both lowered at the same time without interfering with the passage of air through the other of the pair of adjacent courses or sections. For example, if all of the closures were positioned at the upper open ends of the unit 40 and all of these closures were raised to their upper or open position the air 'could still not pass down through the courses in the unit as the adjacent raised closures would substantially meet and block the passage of air past the closures. By alternating the position of the closures at the upper and at the lower ends of the courses it is possible to open and close each course as desired irrespective of the position of the closures for the next adjacent courses. The peaked shape of the closure is such that the air may readily pass around the closures and not be unduly restricted and may freely flow through the courses not shut off by the appropriate positioning of its respective closure.

To provide for the adjustable. mounting of the closures and to support the same upon the unit 40 there are provided the upper brackets 4| and the lower brackets 42 which extend horizontally across each of the several courses of the unit 40. The upper horizontal bracket 4|, welded or otherwise suitably secured to the arcuate partition wall 39, extends across the upper end of each course intermediate the radial partition walls 38. The lower horizontal brackets 42 are likewise secured to the arcuate partition walls 39 and positioned between the radial partition walls 38, are positioned below the upper brackets and near the lower ends of the courses or sections of the unit 40. The detailed construction and assembly of the parts referred to. are shown in Figures 5 to 8, inclusive.

A rod 45 extends vertically in the windbox through suitable openings provided in the brackets 4| and 42, the rods 45 being slidable up and down through the openings in the brackets. A washer 48 suitably secured to the upper end of each rod 45 is adapted to engage the upper bracket 4| when the rod is positioned in its lowermost position and thus limits the downward movement of the rod 45. There is a boss or pin 46 extending out from only one side of the rod 45 at a point below the washer 48. A slot or key-way 41 extends through the upper bracket 4| at one side only of the rod 45, the slot 41 being of just sufficient size to permit the boss 46 to be moved therethrough when the boss 46 and slot 41 are in proper alignment. A handle 49 at the lower end of each rod 45 is provided to facilitate the raising, lowering and turning of each rod 45. By proper manipulation of each rod 45 by means of the handles 49 the rods may be positioned as illustrated in Figures 5 and 7 and by raising the rods and properly aligning the bosses 46 and slots 41 the rods may be raised to the position shown in Figures 6 and 8 and locked in that raised position by turning the rods to place the boss 46 out of alignment with the slot 41.

The lower closures 46 are secured to, and supported by, the rods 45 in the manner illustrated in Figures 5 and 6. When the rod 45 is in lowered position the lower closure 44 is down away from the lower end of the respective course trates the raised and open position of the upper closure 43 when the rod is locked in its upper position. Since'closures 43 are not next adjacent to each other but are alternately disposed the air may freely flow around a raised upper closure and enter the upper open end of the course above which it is raised. When in the position shown in Figure 8 air may freely flow around the raised closure 43 and flow down through the course beneath it and hence through the wind box to the tuyere entrances.

The handles 49 may be operated from within the furnace when cold by reaching out through the tuyres and seizing the handles 49 to manipulate the same. However, it may be desired to manipulate the handles 49 to change the positions of the closures from outside of the furnace and for this purpose there is provided a bottom opening 36 in the lower end of the wind box 22 and extending around the annular extent of the wind box. Asuitable plate 31 attached to the wind box 22 by bolts or other suitable means normally closes the lower bottom opening 36 to complete the enclosure of the wind box. When it is desired to manipulate the handles 49 from without the furnace the plate 31 may be temporarily removed to permit the operator to reach in through the opening 36 and to thus manipulate the handles 49 as desired.

The peaked shape of the closure is illustrated in Figure 10. The closures 43 and 44 are similar in shape and are of substantially the same size.

It is noted that the sides of the closures extend downwardly. on an incline or slope in both directions from the center of the closure. Air may easily pass around the closure with a minimum of interference and at the same time the closure may definitely close its appropriate course or section when properly positioned at the open end of the course. All of the closures are positioned with the peak uppermost and the sides extending i downwardly in the general direction of the outin the unit 40 and the air passing down through the course may freely flow therefrom down into the lower part of the wind box, the air passing around the closure 44. When the rod 45 is in the position illustrated in Figure 6 the closure 44 is in raised position to close the lower end of the respective course through the unit 49 and thus blocks any movement of air through that course. Since two lower closures 44 are not next adjacent to each other they may be raised and lowered as desired without interferring with the operation of the next adjacent course. p

The upper closures 43 are secured to. and supported by, the upper ends of the respective rods 45. When the rod 45 is in the lowered position vshown in Figure 7 the closure 43 closes the upper end of the courseover which it is positioned and thus blocks the passage of air therethrough. The shape of the closure 43 with its inclined sides is such that air is not unduly blocked by th closure but may easily pass by the closure to enter the next adjacent course if it is open. Figure 8 illuslets to the tuyres, the shape of the closures facilitating the flow of air toward the outlets. The relationship of the upper and lower closures ar in reverse, in that when the lower closures are raised they close the lower end of the course where it is positioned and when the upper closures are raised they open the upper end of the course above which it is positioned.

The casing unit 40 is composed of three sections which when joined together form a complete circle extending around the annular extent of the wind box. Figures 4 and 9 illustrate the assembly of the three sections and the manner of joining them togeth r. At the ends of each of the three arcuate sections flanges 50 and 5| extend toward the next adjacent arcuat section of the unit, the upper flange 50 extending in one direction and the lower flange 5| extending in the opposite direction. Therefore, at each junction of the arcuate sections of the unit there is provided overlapping flanges, flange 50 being positioned above flange 5| and positioned at a distance therefrom. An internally threaded sleeve 52 is welded or otherwise suitably secured to the matingflanges 50 and 5| and extends therebetween, each sleeve 52 being positioned in aligned openings in the mating flanges 59 and 5| as shown in Figure 9. In this manner the three arcuate sections of the unit are firmly secured together and-thus form one annular air control device within the wind box.

Three screw posts 53 extending vertically down through the wind box 22 are threadably engaged within each of the respective threaded sleeves 52. The upper ends of each of the screw posts 53 extend through openings in the upper wall of the wind box 22 to a position externally of the wind box, the screw posts 53 being freely rotatable relative to the wall of the wind box through which it extends. A handle 54 non-rotatively secured to the upper end of each screw post 53 provides means for rotating the screw posts 53. A sprocket wheel 55 is also non-rotatively secured to the upper end of each screw post 53 so as to rotate therewith. A chain 55 connecting all of the sprocket wheels 55 causes the rotation of one sprocket wheel to be transmitted to all the other sprocket wheels and thus provides for the simultaneous rotation of all the three screw posts 53. As shown in Figure 3, idler wheels 51 mounted on top of the wind box are provided for keeping the chain 56 in proper position and to permit the encircling of the furnace wall by the chain 55. i

It is therefore seen that by turning one of the handles 54 all three screw posts 53 are rotated accordingly and that by reason of the threaded engagement of the screw posts 53 in the threaded sleeves 52 the unit 40 is raised or lowered in the wind box. By turning the handle 54 in one direction the unit 40 will be raised vertically upward in the wind box away from the outlets and by turning the handle 54 in the opposite direction the unit 40 will be lowered in the wind box toward the outlets to the tuyeres. The engagement of the unit 40 within the wind box 22 is such that the sides of the unit slidably engage the inner walls of the wind box as the unit is raised or lowered.

In the operation of furnaces and particularly of cupolas it is often desired to rebuild the interior of the furnace shaft with different thicknesses of lining. In some operations the lining 24 will be made relatively thin and in other operations the lining 24 will be made relatively thick. By changing the thicknesses of the lining 24 the inner diameter of the furnace shaft is changed. A change in the inner dimensions of the furnace is such as to vary the requirement of the air blast to be delivered into the shaft through the tuyres. If the air blast is not supplied in accordance with the inner dimensions of the furnace shaft a properly controlled melting zone within the furnace may not be obtainable as the air blast entering through the tuyres may either extend too far and sweep entirely across the shaft to the opposite wall or may not extend inwardly far enough toward the center of the shaft. Heretofore in the rebuilding of the furnace lining in such a manner as to vary the diameter of the furnace shaft, it has often been necessary to tear down the 'wind box and to change the size of the wind box and to re-locate the air control device within the wind box so as to meet the requirement of the rebuilt furnace shaft. However, by being able to change the effective cross-sectional area of the wind box (either enlarged or diminished) and by being able to raise and lower the air control device relative to the outlets to position the unit 40 at the proper elevation in the wind box it is possible to adiustably regulate the wind box to supply an air blast to the tuyeres in accordance with the requirements of the furnace. Also, even when the inner diameter of the furnace remains the same but is operated under different operating conditions, or when the furnace has deficiencies in balanced design and proportions, or when there is a lack of predetermined measurement data, some experimenting may be required to determine the best location of the air control device within the wind box. By having the aircontrol unit adjustably movable longitudinally of the. furnace as herein suggested the best location for the unit in the wind box may be readily determined and its location there fixed. It is understood that other suitable means may be provided for adjustably positioning the air control device within the wind box, the screw posts threadably engaging the unit as here illustrated being a preferred form of the raising and lowering means given by way of example.

Figure 11 is a diagrammatical view used for better illustrating the cooperative relationship of the parts and for indicating the various arrangements which may be had in the utilization of my apparatus. The arrangement shown in Figure 11 is only one of many arrangements which may be obtained and is given only by way of example. In the particular arrangement of parts shown in Figure 11 all of the upper closures 43 are shown in raised or open position and every other of the lower closures 44 are shown in raised or closed position. It is obvious that a multitude of variations in the lay-out may he arrived at. For example, every other upper closure may be lowered to close position or every third upper closuremay be lowered to closed position, or every lower closure may be lowered to open position or every third closure may be raised to closed position. Likewise, many combinations and permutations of such suggested arrangements may be made.

It is seen that my apparatus is extremely flexible in its use so as to be adaptable to many operating conditions of the furnace and to meet variable requirements. By closing appropriate courses or sections of the unit and leaving others open the flow of air through the wind box may be modified as desired and'by controlling the flow of air through the wind box in accordance with the variable conditions encountered, the air blast may be supplied to the tuyeres at substantially equal velocities. Changes in the total air blast received from the air blower may be provided for by suitably adjusting the closures in any selected arrangement to meet the need and upon the fixing of the parts in a favorable relationship the air blast is modified to be supplied to the tuyeres at substantially equal velocities. Other operating conditions such as the internal diameter of the fumaceshaft, the character of the charge within the furnace and the resistance encountered by the air blast, and other variable factors may be satisfactorily met and the problems inherent therein may be solved by the flexible apparatus here provided. The method of handling the air blast supplied to a wind box and of modifying the flow of the air in the manner here described produces results not heretofore obtainable. Many other advantages and operating characteristics of my new apparatus and method are discernible from the present description and disclosure and by its comparison with prior apparatus and methods. The principle of my invention disclosed by way of example in the particular embodiment here shown includes all of its inherent advantages, operating characteristics and the possible combination and permutations suggested or apparent in the present disclosure.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to cross-sectional area of the wind box into a plurality of separate and substantially vertical courses for the flow of air therethrough, closures carried by the unit for closing off the flow of air through each of said courses, the closures for adjacent courses being alternately positioned adjacent opposite ends of the courses, adjustable means for adjustably positioning ,each of said closures relative to said partitions to open and close said courses, the variable selective opening and closing of said courses providing a variable modification of the air flow through said unit, and means for adjustably changing the spacing of said unit relative to the tuyere entrances to provide for varying air flow requirements.

2. In a furnace having a wind box for supplying blown air to a plurality of outlets communicating with tuyres entering said furnace, said wind box having an inlet adapted to communicate with a source of blown air, a device for controlling the flow of air through the wind box comprising a plurality of spaced vertically disposed partitions forming a plurality of openended sections distributed around the cross-sectional area of the wind box, closures for. closing the flow of air through each .of said sections, ad-

justable mounting means for adjustably mounting said closures in selected open and closed positions, adjacent closures being positioned in alternate relationship at opposite open ends of said sections to permit the flow of air past said closures and through the wind box, and raising and lowering means for adjustably fixing the position of the device in the wind box relative to the said outlets, the flow of air through the wind box being variably modified in passing through the sections selectively opened by closures and in encountering sections selectively closed by closures, the variable modification of the flow of air by said device being adjustable torequirements of the furnace by the raising and lowering of the device relative to the outlets.

3. In a furnace having a wind box for supplying air to a plurality of outlets communicating with tuyres entering said furnace, said wind box having an inlet adapted to communicate with a source of blown air, an air control device comprising a plurality of spaced walls dividing the cross-sectional area of the wind box into a plurality of sections disposed longitudinally of the wind box, said sections having open ends to permit the flow of air therethrough, a plurality of peaked closures for closing opposite ends of the adjacent sections of said plurality of sections to obstruct the fiow of air therethrough, said peaked closures having sloping sides extending on an incline longitudinally of the wind box toward said outlets to facilitate the flow of air around said closures, and adjustable means carried by said spaced walls for moving said closures longitudina'lly of the wind box to adjustably open and close said opposite ends of the adjacent sections,

the selective opening and closingof said sections providing for, the variable modification of the airflow, throughout the cross-sectional area of the wind box, in pasing through the wind box to be supplied to said outlets at substantially equal velocities.

4. In a furnace having a wind box forming a common distributing chamber for supplying blown air to a plurality of tuyeres communicating with the said furnace, said wind box having an inlet adapted to communicate with a source of blown air, a plurality of spaced partitions positioned in said wind box intermediate of, and at a distance from, said inlet and the entrances to said tuyeres, the said partitions being disposed longitudinally of the wind box and substantially equally dividing the wind box into a plurality of courses arranged around the cross-sectional area of the wind box to provide communication between the portion of the wind box adjacent the inlet and the portion of the wind box adjacent the tuyre entrances, closure means for selectively opening and closing each of said courses to control the flow of air through said courses, the control of the flow of air through said courses modifying, the flow of air through the wind box to said tuyres.

5. In a furnace having a wind box for supplying air to a plurality of outlets communicating with tuyres entering said furnace, said wind box having an inlet adapted to communicate with a source of blown air, air control means positioned in said wind box intermediate of, and at a' distance from, said inlet and said outlets in the path of the flow of air through the wind box, said means comprising dividing means for dividing the cross-sectional area of the wind box into a plurality of courses extending longitudinally of the wind box, closure means for selectively closing off selected courses against flow of air therethrough and adjustable means for adjustably fixing said, closure means in open and closed positions, the opening and closure of selected courses of said plurality of .courses modifying the flow of air through thewind box to be supplied to said outlets at modified velocities. r

6. In a furnace having a wind box for supplying air to a plurality of outlets communicating with tuyres entering said furnace, said wind box having an inlet adapted to communicate with a source of blown air, air control means positioned in said wind box intermediate of, and

at a distance from, said inlet and said outlets in the path of the flow of air through the wind box, said means comprising dividing means for dividing the cross-sectional area of the wind box into a plurality of courses extending longitudinally of the wind box, closure means for selectively closing off selected courses against flow of air therethrough, adjustable means for adjustably fixing said closure means in open and closed positions, and means for adjustably mov-- ing said air control means longitudinally of the wind box relative to said outlets to provide control of the flow of air through the wind box in accordance with the requirements of said furnace, the opening and closure of selected courses of said plurality of courses modifying the relative velocity of the flow of air supplied to said outlets. I

7. In a furnace having a wind box for furnish ing air to a plurality of outlets communicating with tuyres entering said furnace, the wind box having an inlet in communication with a source of said air, an air-control unit positioned in said wind box intermediate of, and at a distance from. said inlet and said outlets and extending around the cross-sectional area of the wind box, said unit having a plurality of open spaces therein formed by spaced members extended across said wind box, said unit having a plurality of separate closures for each of said open spaces and having mounting means for selectively moving each or said closures into open and closed positions independently of the other closures, the selective opening and closing of said open spaces by said closures providing a modification of the flow of air in the wind box through said unit to be supplied to said outlets at velocities modified by the said unit.

8. In a furnace having a wind box for supplying a blast of air to a plurality of tuyeres, said wind box having an inlet adapted to communicate with a source of an air blast and having outlets in communication with said tuyeres, a plurality of spaced plates extending longitudinally of the wind box and distributed around the crosssectional area of the wind box intermediate of. and at a distance from, said inlet and said outlets and means for selectively closing of! the space between said spaced plates to obstruct the flow of air therethrough, said closing means being independently operable for each of said spaces, the selective closing of said spaces providing a variable modification of the cross-sectional area of the wind box through which the air blast may pass to supply the air blast to said tuyeres in accordance with the requirements of said furnace.

9. In a furnace having a wind box for supplying a blast of air to a plurality of tuyeres, said wind box having an inlet adapted to communicate with a source of an air blast and having outlets in communication with said tuyeres, the combination of first means positioned in the wind box intermediate 0!, and at a distance from, the inlet and the outlets for dividing the wind box jnto a plurality of sections extending around the cross-sectional area of the wind box, second means for selectively closing oil said sections as required to enlarge and diminish the cross-sectional area of the wind box through which the air blast may pass from the portion of the wind box adjacent the inlet to the portion of the wind box adjacent the outlets, said air blast being modified in velocity by said first and second means to be supplied to the outlets at said modified velocities, and third means for adjustably fixing the position of said first and second means in the wind box relative to said outlets to selectively vary the modification of the air blast in accordance with the requirements of said furnace.

10. The method of supplying an air blast to a plurality of furnace tuyeres. comprising: the step of passing an air blast through a distributing chamber; dividing the flow of the air blast through the chamber; selectively blocking portions of the air blast to modify the flow of the air blast to the tuyeres to supply the air blast to the tuyeres at equal velocities; re-uniting the divided flow of air; adjustably spacing said blocking of the air blast from the tuyres to vary the modification of the air blast in accordance with the requirements of the furnace; and delivering the modified flow of air to the said tuyeres.

HERBERT A. REECE.

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