US3424446A - Cupolas - Google Patents

Description

Jan. 28, 1969 R. R. SCHANEN CUPOLAS Sheet Filed Feb.

1N VENTOR ROBERT R SCHANEN ATTORNEYS Filed Feb. 2, 1966 Jan. 28, 1969 R. R. SCHANEN CUPOLAS v INVENTOR ROBERT R. SCHANEN ATTORNEYS United States Patent 3,424,446 CUPOLAS Robert R. Schanen, Port Washington, Wis., assignor to Modern Equipment Co., Port Washington, Wis., a corporation of Wisconsin Continuation-impart of application Ser. No. 400,673, Oct. 1, 1964. This application Feb. 2, 1966, Ser. No. 524,526 US. Cl. 26631 Int. Cl. C21b 7/08; F27b /12 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to improvements in cupolas, and is a continuation-in-part of my application Ser. No. 400,673, filed Oct. 1, 1964, now Patent No. 3,331,598.

In conventional cupolas a charge receiving section with a charging opening is provided between the cupola and the aligned exhaust stack through which opening the charge of coke, limestone, scrap metal, etc. is deposited into said cupola. When the cupola is arranged with its principal gas offtake below its charge receiving section it is highly desirable during the melting operation to prevent air from freely entering the upper, charge pre-heating area of the cupola through said charging opening, however, because the mixture of said air with the gases of combustion within the cupola can cause a dangerous explosive condition. In addition, the entry of a large volume of air into the cupola an the mixture thereof with the cupola gases greatly increases the volume of gases which must be constantly drawn out of said cupola during operation, thereby substantially increasing the size and initial cost of the takeoff pump and gas cleaning equipment, as well as greatly increasing the operating cost of the cupola.

When the level of the charge within the cupola is relatively high the entry of air through the charging opening may not be such a critical problem, because the charge itself forms a plug-like closure in the top of the cupola to prevent the free entry of said air, but as the level of said charge is lowered during the melt down, as when it is intended to empty the cupola or when said level is carelessly allowed to descend further than is desirable during the normal melting operation, air flows into the cupola interior through the charging opening at an increasing rate, with the harmful results hereinabove described. In order to eliminate this undesirable situation, attempts have been made in the past to provide a cover in the charge receiving section of the cupola to close off the charging opening, but such prior cover devices have not proven entirely satisfactory. For one thing, it has been found that a gas pocket is formed in the space between said closure and the charge therebelow, which gas accumulation an be dangerously explosive.

With the above considerations in mind, one of the principal objects of the present inveniton is to provide a novel cupola design incorporating an offset exhaust stack opening and having a novel cupola cover which can be utilized to prevent outside air from freely entering said cupola through the charging opening, particularly during the melt down operation, said cover device being adapted ice to automatically descend with the level of the charge to eliminate the possibility of a dangerous gas accumulation forming above said charge. Said closure apparatus is claimed in my aforementioned pending patent application Ser. No. 400,673 of which this application is a continuation-in-part.

Another shortcoming of prior cupola designs is that with the exhaust stack opening arranged immediately above and in alignment with the cupola, as it is in conventional cupolas, a substantial amount of the gases created in said cupola tend to escape or belch from the charging opening and flow into the interior of the foundry, where they cause a noxious and dangerous condition. To overcome this situation many such cupolas are provided with fan means adapted to continuously handle cupola gases plus a quantity of air drawn inwardly through said charging opening during the operation of the cupola in order to create an indraft designed to ensure that the cupola gases flow upwardly into the exhaust stack, rather than outwardly through said charging opening. In addition, a large number of cupolas are provided with a gas cleaning system associated with the exhaust stack which is designed to cleanse the cupola gases before they are discharged to the atmosphere. Such systems are required by law in many localities. Unfortunately, in those cupolas wherein a large quantity of air is drawn inwardly through the charging opening to create a heavy indraft, as described, said outside air also passes through the cleaning system along with the cupola gases, thereby necessitating an expensive, large-capacity apparatus which consumes excessive power in proportion to the volume of cupola gases cleaned thereby.

With the above in mind, an important object of the present invention is to provide a novel cupola charge receiving section design featuring an offset exhaust stack opening and having an enlarged body section adapted to cause the rising cupola gases and dust, etc. to flow laterally away from the charging opening and upwardy through said offset exhaust stack opening, thereby minimizing the amount of said gases which escape through said charging opening. With said novel cupola charge receiving section design it is unnecessary to continuously draw a large quantity of outside air inwardly through the charging opening to create an indraft during operation and, consequently, a smaller, more efircient and economical gas cleaning system can be employed than has heretofore been possible. This important feature of the present invention was disclosed in part in my aforementioned application Ser. No. 400,673 but was not claimed therein. Moreover, the present continuation-in-part application discloses several modified forms of offset stack with charge-receiving arrangements having enlarged bodies which can be employed within the scope of the invention.

With the above and other objects in view, which other objects and advantages will become apparent hereinafter, the invention comprises the novel cupola charge receiving section designs illustrated and described herein and any and all variations or modifications thereof as may come within the spirit of said invention and within the scope of the appended claims.

In the accompanying drawings, illustrating several forms of the present invention, and wherein like reference characters designate the same or similar parts in all of the views:

FIG. 1 is a perspective view of a cupola having an offset exhaust stack opening and having a movable cover device;

FIG. 2 is a fragmentary side elevational and vertical sectional view of the cupola illustrating in FIG. 1 showing the novel cover device in its raised position in full lines, and said vertically-movable cover being shown in broken lines in its lowermost position;

FIG. 3 is a sectional view through another form of cupola charge receiving section having an offset stack opening and an enlarged body section;

FIG. 4 is a horizontal sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a vertical sectional view of another modified form of cupola charge receiving section having an offset stack opening;

FIG. 6 is a vertical sectional view of a cupola charge receiving section having an enlarged and offset body;

FIG. 7 is a vertical sectional view of another modified cupola charge receiving section design having an enlarged and offset body and an offset stack opening; and

FIG. 8 is a horizontal sectional view taken along line 88 of FIG. 7.

Structure disclosed and claimed in application Ser. No. 400,673

Referring now more particularly to FIG. 1 of the drawing, the numeral 9 designates a cupola of the general type herein concerned, and shown adjacent said cupola is a fragmentary portion of the scaffolding and framework 27 which is designed to support the charging bucket rails 26 and bucket-conveying mechanism (not shown) in the illustrated cupola assembly, as well as the other equipment necessary in a complete, automated foundry complex. It is to be understood, of course, that the particular design of the cupola charging mechanism and other incidental and related foundry equipment is in no way critical to the present invention, and the invention is not to be limited to use in a complete unit identical to that shown.

The cupola 9 illustrated in FIG. 1 is generally cylindrical in form and includes a melting zone 11, there being the customary blast ring and tuyeres 25, etc., as is well known in the art, and mounted thereabove is an annular gas take-off ring 12. The latter is connected to a vacuum pump and emission cleaning mechanism (not shown), and during the melting operation said apparatus performs the important function of continuously exhausting gases from the cupola interior, said gases being cleaned and vented to the atmosphere or recuperated for use in the tuyeres. The upper portion 10 of the illustrated cupola is tapered downwardly, although a straight, cylindrical design will ordinarily be employed, and the charging opening 13 is formed thereabove. Projecting upwardly from said cupola, and offset therefrom is the stack 14, the offset design of said stack being an important feature of the invention, as will be hereinafter seen.

In lieu of an annular gas take-off ring 12 formed integrally on the cupola itself, many cupola installations utilize a gas conditioning and cleaning apparatus which communicates with the exhaust stack 14, which is a less expensive arrangement. Unfortunately, however, the latter design presents some serious problems with respect to the size and power requirements of the conditioning equipment and the elimination of these problems is one of the principal objects of the invention disclosed in this continuation-in-part application, as will be later described.

In the operation of a cupola of the general type illustrated in FIG. 1, a charging bucket (not shown) is filled at a lower, loading station with a charge of coke, scrap metal, limestone, and whatever other additives or innoculants are required for the desired end product, and said bucket is conveyed upwardly on the rails 26 by a suitable, power-driven hoist. When said charging bucket reaches the upper end of said rails it is conveyed through the cupola opening 13, and is opened either automatically or by remote control to discharge its contents into the cupola, said bucket then returning to the loading hopper.

As hereinabove mentioned, one disadvantage of prior cupolas of the general type herein concerned is that air entering the charging opening 13 during the melt down, or at any other time the charge level becomes abnormally low, greatly increases the required capacity of the gas take-off equipment and reduces the efficiency and economy of the melting operation. Moreover, in prior cupolas wherein a cover has been provided to prevent the entry of air under such circumstances, it has been found that the space immediately below said cover collects dangerously explosive gases of combustion.

Referring now more particularly to FIG. 2 of the drawing, it will be seen that the upper portion of the illustrated cupola is provided with a horizontal platform 15 adjacent the offset stack 14, and mounted thereon is a bracket 16 supporting a vertical sleeve member 17 which is in alignment with the internal center line of the cupola proper. Projecting through, and slidably journaled in said sleeve 17 is an elongated vertical rod 18, said rod being of a length to extend downwardly from said sleeve to a point within the cupola adjacent the gas exhaust outlet 12, and carried on the lower end of said rod is a circular cover 19. Said cover is preferably elliptical in vertical cross section, and is of a diameter slightly smaller than the diameter of the upper portion 10 of said cupola, as illustrated in broken lines in FIG. 2.

As is shown in FIG. 1, secured to the upper end of said vertically-movable cover-supporting rod 18 is a sheave 20, and trained thereabout is a cable 21. In the illustrated arrangement, one end of said cable is deadended to the framework, as at 22, and after passing around a stationary sheave 23, the opposite end of said cable is secured to a power-driven drum or winch 24, thus providing mechanical means for raising said rod 18. Said cover is movable from the raised position shown in full lines in FIG. 2, wherein it is spaced above the charging opening 13, to the lowered position wherein it is located adjacent the cupola gas take-off ring 12, as illustrated in :broken lines. With respect to said cover-elevating mechanism, incidentally, it is contemplated that numerous other equivalent devices could also be used.

In the use of a cupola having the illustrated cover device the cover-supporting rod 18 is initially raised to the full line position shown in FIGS. 1 and 2 by means of the cable and winch mechanism 21-24 or other equivalent device, thus positioning the cover 19 above the cupola charging opening 13. A sufficient number of charges are then deposited in the cupola to fill the same to a point just below said charging opening, which line is designated by the letter A in FIG. 2. During normal operation when the charge level within the cupola has been reduced the approximate equivalent of one charge a new charge is added, thus again bringing the level to the approximate point A. As hereinabove mentioned, when the charge level is thus maintained relatively high, the problem of air entering the cupola interior is not critical because said charge functions as a plug to minimize the volume of air that can enter the cupola through the charging opening. When the charge level is allowed to descend substantially more than one charge, however, as during the melt down or as occasionally happens through negligence or inadvertence on the part of the operator, the effectiveness of the relatively porous charge as a closure is diminished and the outside air flows into the cupola interior, with the undesirable results hereinabove described. It is in these instances that the novel device 19 is intended to be utilized.

When it is determined that the level of the charge within the cupola is too low for said charge to function as an effective closure, which determination can be made either electronically or by other suitable means, the cable 21 is automatically or mechanically released and the rod 18 descends by gravity to a point where the cover 19 on the lower end thereof rests on the surface of said charge, thus preventing the free passage of air into the cupola through the charging opening.

If it is desired to continue the melting operation without replenishing the charge, as during the melt down, the cover device 19 is adapted to ride downwardly on top of the charge by gravity. The result is that said cover not only substantially closes off the top of the cupola to prevent the free flow of air therein, as described, but by descending with the level of the charge during the melting operation there is no space between said cover and the charge in which gas can accumulate, as in prior cupola cover assemblies, and which can be extremely dangerous.

When the level of the charge descends to a point adjacent the annular gas take-off ring 12 in a cupola of the type illustrated in FIGS. 1 and 2, the problem of dangerous gas accumulation in the cupola interior ceases, because said exhaust device functions to continuously draw off the gases therebelow, as described. Thus, when the cover 19 reaches said lowered point an enlarged collar 18' on the upper end of the cover-supporting rod 18 is designed to abut the top of the sleeve 17, thereby preventing further downward travel of said rod and cover and maintaining the same in the broken line position of FIG. 2 until the melt down has been completed. When it is desired to recharge said cupola, said rod and cover are again raised by means of the cable and winch 21-24, or other suitable mechanism, to a position above the charging opening 13.

From the foregoing detailed description it will be seen that the cover device illustrated in FIGS. 1 and 2 can be utilized to minimize the fiow of air through the charging opening and into the cupola, thus substantially reducing the size and capacity of the required gas withdrawal and reconditioning equipment associated with the gas take-off ring 12 and providing a complete unit which is not only less expensive in design, but which is considerably less costly to operate than prior units of the same general type. Moreover, the vertically-movable nature of said cover assembly eliminates the possibility of an explosive gas build-up within the cupola.

While a simple, preferred form of cover assembly has been illustrated and described herein, it is to be understood that numerous variations or modifications thereof could be made therein while still incorporating the basic novelty of the present invention. For example, it is contemplated that an electronic sensing system could be employed to control the descent of the cover 19, in lieu of the simple gravity descent arrangement utilized in the illustrated form of the invention. Further, and as hereinabove mentioned, other means could be employed to raise the cover in lieu of the cable and winch mechanism shown, and the design of said cover and its supporting apparatus could obviously be modified.

Structure of present continuation-impart application As hereinabove mentioned, while the cupola 9 illustrated in FIGS. 1 and 2 is provided with an annular gas take-off ring 12 formed integrally on said cupola, more often the gas take-off and cleaning apparatus is connected to and communicates with the upper portion of the gas exit conduit or stack 14, said apparatus being designed to cool and cleanse said exhaust gases before discharging the same to the atmosphere. Unfortunately, with the latter type of gas take-off arrangement a quantity of the gases, dust, smoke, etc. rising in the cupola tend to escape or belch outwardly through the open charging door 13 and contaminate theinterior of the foundry, which is highly undesirable, of course. To overcome this situation, such conventional cupolas are usually provided with fan means designed to continuously draw a quantity of air inwardly through said charging opening in order to create an indraft designed to draw said gases etc. away from said charging opening and to convey the same upwardly through said exhaust conduit 14. With this type of arrangement, however, the outside air thus drawn into the exhaust conduit is necessarily passed through the gas cleaning system along with the cupola gases with the result that a relatively large capacity, expensive cleaning apparatus is required, and excessive power is consumed by said apparatus in proportion to the volume of cupola gases cleaned thereby.

Referring now to FIGS. 3 and 4 of the drawings, illustrated therein is a cupola 9 having an enlarged chargereceiving section and offset exhaust conduit arrangement generally similar to that disclosed in FIGS. 1 and 2, but wherein said cupola is not provided with an integral annular gas take-off ring nor does the unit include a vertically movable cover device such as that hereinabove described. In the type of cupola illustrated in FIGS. 3 and 4 the exhaust gas take-off and cleaning apparatus (not shown) is connected to and communicates with the upper portion of the exhaust conduit 14. As hereinabove mentioned, said cleaning systems are designed to cleanse the exhaust gases before discharging the same to the atmosphere and are required by law in many communities.

It will be noted that the charging section, which is designated by the numeral 30, of the cupola illustrated in FIGS. 3 and 4 is substantially larger in cross section than the charging sections in conventional cupolas. More over, said enlarged charging section 30 is offset relative to the vertical center line of the cupola 9 and extends laterally rearwardly a substantial distance therebeyond, the exhaust opening 14' being offset from the cupola center line and the exhaust conduit 14 projecting upwardly thereabove as shown. The result is that the gases of combustion and dust, etc. rising in the cupola are caused to flow at an oblique angle away from the charging door opening 13, as indicated by the arrows, thus minimizing the tendency of said gases to flow outwardly or belch from said charging opening as in conventional cupolas.

In accordance with the present invention it is preferred to utilize suitable fan means to draw a small quantity of air inwardly through the cupola charging opening 13 in order to promote the flow of the exhaust gases upwardly through the exhaust opening 14' and conduit 14, but because the normal path of said gases is directed away from said charging opening due to the offset nature of the exhaust opening the volume of said indraft can be substantially less than that employed in conventional cupolas. As a result, in the present invention the size and power requirements of the gas cleaning apparatus need not be as large as those required in conventional cupolas wherein it is necessary for the cleaning apparatus to handle both the cupola gases and the relatively large volume of outside air continuously introduced into the system.

FIG. 5 of the drawings shows a modified form of cupola having an enlarged and laterally-projecting charging section 30 and offset exhaust opening 14 and conduit 14, and showing a typical charging bucket 31 positioned in said charging section. Said charging bucket is used to fill the cupola 9 with the charge of coke, limestone, scrap metal, etc. In conventional cupolas it has been found that when said charging bucket 31 is in discharging position the gases rising from the cupola are blocked or partially blocked by said bucket and prevented thereby from freely flowing upwardly into the exhaust stack, a substantial portion of said gases being directed outwardly through the charging opening 13 instead. It is to overcome this objectionable situation that the enlarged charging section 30 characterizing the present invention has been designed, said enlarged charging section minimizing the obstruction formed by said bucket 31 and permitting the gases of combustion to readily flow therearound and upwardly through the exhaust opening, as indicated by the arrows. The result is that due to the combined effect of the offset exhaust opening 14' and enlarged charging section 30 the belching of gases, smoke, dust, etc. outwardly through the open charge door 13 during the charging operation is practically eliminated. In this form of the invention, too, a small quantity of outside air is preferably drawn inwardly through said charging opening 13 to create an indraft to promote the flow of cupola gases upwardly into the exhaust conduit 14 but the volume thereof can be substantially less than that required in prior cupolas, thus reducing the size and power requirements of the gas r cleaning system.

FIG. 6 shows another modified form of cupola having an enlarged charging section 30, but which charging section projects forwardly of the cupola 9, as shown, and wherein the charge door 13 is located in the projecting end thereof. In this form of the invention it is not necessary that the exhaust opening 14 be offset from the vertical center line of the cupola inasmuch as the offset position of said charging opening 13 relative to the cupola minmizes the possibility of exhaust gases flowing or belching therefrom. It will he noted that in the illustrated design the lower end portion of the exhaust conduit 14 is flared somewhat to promote the entry of the rising gases into said conduit.

In FIG. 7 there is shown another form of cupola incorporating both an enlarged and forwardly-projecting charging section 30 similar to that illustrated in FIG. 6, and an offset exhaust opening and stack 14. This form of the invention provides the advantageous features of both a forwardly-offset charging door and rearwardly-otfset exhaust opening to minimize the belching of cupola gases through said charging door 13. As will be seen by the directional arrows, a relatively small indraft need be created through said opening 13 to ensure that the exhaust gases rise in the conduit 14. As is illustrated in FIG. 8, which is a horizontal sectional view through the cupola shown in FIG. 7, with the enlarged charging section 30 the air drawn inwardly through the opening 13 tends to circulate completely around the periphery of the rising gas column, thus causing more rapid and complete combustion of said toxic gases than is obtained in conventional cupolas.

From the foregoing detailed description it will be seen that the novel enlarged charge-receiving section and offset exhaust opening characterizing the forms of the present invention illustrated and hereinabove described provide several important advantages over prior cupola designs. With the present design it has been found that the cupola gases, dust, and smoke, etc. do not tend to escape or belch from the charging opening as in conventional cupolas. Moreover, a relatively small indraft i required to ensure proper directional flow of such gases, thereby permitting the use of a smaller capacity gas cleaning apparatus than those heretofore employed and providing substantial savings both in the initial cost and operating expense of said apparatus.

It is to be understood that while the illustrated forms of the present invention are preferred, it is contemplated that numerous variations thereof will undoubtedly occur to those skilled in the art and it is intended to include herein not only the cupola charge-receiving section designs illustrated and described, but also any and all modifications or variations thereof as may come within the spirit of said invention and within the scope of the following claims.

What I claim is:

1. An improved cupola structure, comprising a lower melting furnace section, said melting furnace section standing upright and being substantially cylindrical in form, an enlarged charging section on and communicating with the upper end of said upright cylindrical melting furnace section, said charging section being substantially larger in cross section than said melting furnace section and extending laterally thereof; a charge-receiving opening in one side of said enlarged charging section; and an exhaust stack communicating with and extending upwardly from said charging section at a point spaced laterally from said charge-receiving opening and also offset relative to said melting furnace section, the offset arrangement of said exhaust stack causing all of the exhaust gases flowing upwardly from the melting furnace section through said charging section to the stack to flow obliquely away from said charge-receiving opening to prevent said gases from escaping therethrough.

2. The cupola structure recited in claim 1 wherein said enlarged charging section is of a size whereby when a charging bucket is positioned therein rising exhaust gases from the melting furnace section therebelow can flow freely around said bucket and upwardly through said exhaust stack.

3. The cupola structure recited in claim 1 wherein said enlarged charging section is of a size permitting air entering said charge-receiving opening to circulate completely around the periphery of said rising exhaust gases to promote the complete and rapid combustion of said gases.

References Cited UNITED STATES PATENTS 606,667 7/1898 Humphreys 126120 1,447,071 2/ 1923 Gieseoke 26329 2,689,659 9/1954 Drake 2l4-18 2,796,235 8 6 1957 Carpenter 12662 J. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.

US. Cl. X.R. 266-27

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