US1627536A - Process of and apparatus for operating cupolas - Google Patents

Description

May 3, 1927.

F. 'K. VIAL. ET AL PROCESS OF AND APPARATUS FOR OBERATING CUPOLAS Filed Jan; 19, 1925 Patented May 3, 1927.

4 UNITED STATES PATENT OFFICE.

FREDERICK K. VIAL, OF LA GRANGE, AND GEORGE S. EVANS, 01 OAK PARK, ILLINOIS, ASSIGNORS TO GRIFFIN WHEEL COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF MASSACHUSETTS.

PROCESS OF AND APPARATUS FOR OPERATING CI IPOLAS.

Application filed January 19, 1925. Serial No. 3,221.

In the operation of a foundry cupola, it is the usual custom to deposit alternate charges of coke and the metal to be melted, burning the lowermost charge otv coke in 5 contact with the metal and through air admitted to the bottom of the cupola. The ultimate combustion of the carbon in the cupola must be and always is incomplete. In practice the carbon finally burns to about m half by weight of carbon dioxid and half by weight of carbon monoxid. Incomplete ('OH'IlHlHtiOll is desired in order to maintain a reducing condition to prevent oxidation of the iron and is necessitated by the cupola construction. The incon'ipletely burned gases pass out at the top of the cupola and are there burned in the air or permitted to disburse. Because of this final incomplete combustion a loss of heating value of well upwards of 40% results.

lization of a practical and cfiicient process and apparatus readily constructed and adapted for commercial use.

The invention contemplates from certain aspects the removal of a part of the hot gas mixture resulting from the combustion of the coke-from a relatively low level in the cupola with the result that. first a reducing atmosphere is maintained in the upper portion of the cupola and second the amount 5 of gas passing up through the subsequent layers of coke and coal being reduced, the passage thereof is at a lower rate and 1ncreased opportunity: is provided to extractmaximum sensible heat from the portion of the gases rising through the cupola.

A further and important object of the invention is the provision of a process for operating cupolas wherein substantial economics both in the fuel and power consumption may be attained in the practical and commercialv operation of foundry cupolas and this withoutcompensating losses occasioned through either reduced or inferior output or deterkiration of the cupola itself through the practice of theinvented process.

Another important object of the invention is the attainment of these and other ends without requiring interference with the ordinary practices employed in foundries in the introduction of the materials into the cupola and the removal of the metal from it.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodimentthereof.

Referring to the drawings. the single figore is a perspective view of an apparatus embodying our present invention, the parts being broken away and shown in section.

In the melting of cast iron in a cupola, alternate charges of coke and iron are delivered into the cupola and the lowermost charge of coke is burned at a zone of combustion to which air of combustion is introduced. At this zone the coke burns to a large percent of CO and a'relatively small percent of CO. In cupola practice prior to the present invention the heat of the combustion of the coke renders incandescent subsequent charges of coke arranged above the lowermost zone and as the gas asses up through this the percentage of G6 has materially'increased until when it passed out at the top it frequently has been as high as 40 or more percent of the rising gases. The specific embodiment of our invention herein to be described contemplates the removal of a substantial part of the gases of combustion from not far above the zone of combustion and before substantial conversion of CO gas to CO gas has been accomplished. The removed gases are burned to convert the remaining CO gas to CO gas in a recuperator through which passes the air of combustion to e delivered to the combustion zone. This recuperator, in accordance with the present invention, is so arranged as to extract from the removed gases the heat of combustion possible in converting the CO gas to CO and the sensible heat contained in these gases as they leave the'cupola.

The portion of the gases of combustion which is not removed passes on up through the successive layers and on out at the top of the cupola. Since these gases are greatly reduced in volume they have greater time to pass through successive layers and a larger percentage of sensible heat is extracted from them than was possible when all the gases passed out at the top of the cupola. \Ve do not want .it understood, however, that we desire the invention confined from its broad aspect to any of these particular arrangements although they are properly made the subject matter of particular claims in this application. From a broad aspect and a full survey of the industry it is claimed herein that this invention is the first to successfully provide for the preheating of the air to the foundry cupola with attendant economies and in any manner at all adapted for extended commercial use.

The apparatus shown on the drawing comprises a cupola proper, generally designated at 1, having the usual charging door 2 and supports The charging door is above the bottom 4 of the cupola a distance sutlicient to permit the desired number of alternating charges and coke and iron to be deposited. Reference character 5 indicates a wind box or encircling air chamber, which communicates with the interior of the cupola through a circumferentiallydisposed series of tuyeres 6 spaced apart at equal intervals at the lowermost charge of coke which forms the active zone of combustion. The gases of the combustion resulting pass up through the successively arranged charges of coke and iron, heating them in the usualmanner.

The cupola is charged with alternate layers of coke and iron. And our improved process of cupola operation contemplates the heating of the air blast for the cupola so that the heated air is delivered to the lowermost layer of coke to burn the same and at a temperature sufiiciently higher than that of the atmosphere to materially increase the percentage of carbon dioxide gas as the result of the combustion, and correspondingly to reduce the percentage of carbon monoxide gas therein. And this heated air of the blast'burns the lowermost layer of coke and all of the hot products of combustion pass upwardly through the higher layersof coke and iron to preheat them.

In the embodiment disclosed for carrying out our invention we provide the cupola with a bustle pipe 7 disposed about the cuola and communicating with its interiory conduits 8, terminating'in tiers. This construction is preferably arranged a desired distance above the active zone of combustion and below the charging inlet. These tiers or openings 9 are arranged so that a considerable portion of the unburned gases generated by the combustion in the cupola -may be isolated, in the present case withdrawn from the cupola, and burned whereby to generate heat to be utilized in preheating bustion Lemae the air blast for the cupola. And While various arrangements for heating the air blast are within the contemplation of our invention one of our preferred forms consists of the heating arrangement illustrated in the drawings wherein the heater comprises a body 11 mounted on firm supporting legs 12 and having a combustion chamber l314 at its bottom. chamber is or may be of any usual or preferred material and in the present instance is provided with a fire arch 15 through which extend a number of openings 16 to permit the products of combustion to pass upwardly within the preheater. A hot chamber 17, defined by the arch 15 at the bottom, side walls of the heater at its side, and a plate 18 at its top, receives the hot gases of combustion. A plurality of pipes 19 extend through opposite side walls and across said hot chamber and these pipes open freely into headers 21 and 22 at opposite ends.

These pipes are designed and arranged to convey, and form preheating fines for, the air of combustion for the gases in the comchamber. This air is received through a conduit 23 under forced draft, if desired, and thence through a pipe or conduit 24 in which is mounted a control valve 25, the purpose of which will be presently more fully explained. The conduit 24 communicates freely with the inside of header 21 and the header 22 communicates through a passage 26 with the interior of part let of the combustion chamber. This partis arranged at the side of the body 11 and is in effect a mixing chamber as well as'a combustion chamber. A conduit 27 communieates with the chamber 14 and with the bustlepipe 7 already described.

The plate 18 is provided with a plurality of openings, in which are secured a like number of vertical flue pipes 28, which in turn are secured in a second plate 29 arranged well above the lower plate 18. The pipes 28 conduct the hot gases of combustion from the hot chamber 17 to a second chamber 31 above the pipes 28 and plate 29. The chamber 31 is determined by the plate 29, the side Walls of the preheater and a top plate 32. Above this plate .is a fourth plate 33 and pipes 34 are arranged through the plates 32 and 33 to conduct the products of combustion to a head space 35 at the top of the preheater. which head space communicates with the waste gas outlet-36 which is or may be provided with an exhaust fan 37.

It is intended that the air of combustion for the cupola be preheated in this preheater and we have arranged to conduct it about the pipes 28 and 34 throughout a circuitous path. The air is "admitted through conduit 23 intothe space between the plates 32 and This combustion sociate 33 and about the pipes 34. A conduit 39 communicates with this space and with the interior of the heater beneath the plate 29. WVe provide baflles 41, 42, 43, etc., beneath .the plate 29 andabove. the plate 18, and

these baflles extend in from opposite directions so that theair must pass back. and forth across the preheater as it descends in passing about thepipes 28.

A conduit 44 communicates with the interior of the preheater just above plate 18 and with wind box 5 and serves to carrythe heatedair of combustion from the preheater to the cupola.

The reheater is preferably intimately as d with the cupola 30 that the transferred gasesmay be received'at the combustion chamber of the cupola while they are still hot and when desired at a temperature above their flashing point.

It will be noted that the pipes or flues 19 for the air of combustion for the preheater are arranged in the hot space 17 so that the cold air passes through the hot-- test zone in the preheater.

Prior to our invention accurate control of the combustion in the cupola has been impossible for upon altering the blast the re- -sultant change has been attended by a change in heating rate too disproportionate to be practical. Our invention )ermits of the accurate control of the com ustion and hasthis result as one of its import-ant objects.

The valve 25 controls the amount of air admitted to the combustion chamber of the preheater and through variation of ,this amount of air the extent of combustion in the preheater is in/ turn controlled. Through the control of this combustion the temperature of the air admitted to the cupola is subject to accurate adjustment and t iis without,

sacrificin the usual ability to control the blast itse f at the cupola.

It willbe manifest that the employment of our invention produces a material sav ing in the amount of fuel required to heat the iron to the desired temperature, and. by the same token our invention permits and accomplishes a materialsaving in the amount of air necessary to theoperation of the cupola. this last partly because of the reduced fuel employed and partly also because of the direct transmission of heat for the melting of the iron b reason of the preheating. of the air itse f.

, Of course, the saving of air is important in the conduction of the power necessary to the operation ofthe plant. a t

It is thought that theinvention and many of its attendant advantages will be understood from the foregoing description, and

it w'll be apparent that various changes may be made in the form, construction and arrangement of the parts without departing within the cupola and burning "to preheat the air of combustion supplied to the cupola.

said gases 1 2. The process of operating a' remelting cupola which comprises withdrawing gasesof combustion from the cupola and introduc-' ing air to said gases to burn the same and preheating said air and the air of combustion for said cupola by means of the heat generated by the burningof said gases.

3. The process of operating a remelting I cupola which comprises, charging the cupola with alternate layers of coke and iron, delivering air at a temperature above that of the atmosphere to the lowermost layer of coke to burn the same, and to cause the resulting products of combustion to rise through subsequent alternate layers to preheat said layers. 1 v

4. The process-of operating a remeltingcupola which comprises burning in a heater unburned gases resulting from combustion within the cupola and utilizing the heat of said burning gases to heat the air of combustion supplied to the cupola.

5. A process of operating a remelting cupola which comprises burning in a heater the gases from the cupola combustion and air, and directing both the air of combustion for the cupola and the air of combustion for said gases through said heater,

whereby all of said air ot' combustion is preheated. g

6. The process of operating a'remelting cupola which comprises burning in a heater the gases from the cupola combustion and air, and directing both the air of combustion for the cupola and theair of-combustion for said gases through saidheater and controlling the temperature of the air of combustion delivered to the cupola by vary ing the combustion in said heater.

7. The process of operating aremelting cupola which comprises burning ina heater the gases from the cupola combustion and air, and directing both the air of combustion for the cupola and theair of combustion for said gases through said heater, and controlling the temperature of the air of combustion in said heater through varying the air "of combustion to said heater.

8. The rocess of operating a remelting cupola which comprises burning in a heater the gasesfrom the cupola combustion and air and directing both the air of combustion for the cupola and the air of combustion for said gases, through the heater, said air of combustion for the burning of the uses assing through the hotter portion ot the water.

9. The process of operating a remelting cupola which comprises introducing air into unburned gases resulting trom gombustion "within the cupola to burn said gases and preheating the air blast for said cupola by means of the heat generated by the burning of said gases.

10. The process of operating a reinelting cupola which comprises introducing air into gases resulting from combustion within the cupola to burn said gases, preheating the air blast of said cupola by means of the heat generated by the burning of said gases and controlling the combustion-0t said gases to control the temperature of the blast.

it. The process of operating a remelting cupola which comprises charging the cupola with alternatelayers of coke and iron and burning the charge, withdrawing products of combustion from the cupola after they have passed through-a portion of the charge and utilizing the heat derived from said withdrawn gases to preheat the air blast.

12. The process of operating a remelting cupola which comprises charging the cupola with alternate charges of coke and iron and burning the same, passing the products of combustion through the charge of ironabove the lowermost charge of coke while maintaiping' a substantial part of the gas of combustion out of contact with superposed layers of coke whereby to reduce conversion of CO gas to CO gas.

13. The process of operating a remeltin'g "cnpola which comprisescharging the cupola withalternate layers of coke and iron, burning the charge, withdrawing a percentage of the gases of combustion above the active zone of combustion, whereby the remaining gases passsubstantially slowly through the superposed layers whereby the maximum sensible heat-is extracted therefrom.

M. The process of operating a remelting cupola whichcomprisescharging the cupola with alternate layers of coke and iron, introducing gaseous medium .intosaid cupola at one zone, withdrawing gaseous medium from the cupola at a zone between the layers of combustible material and utilizing the latter medium to effect the thermal characteristics of the mediumbeing introduced.

-15. The process out operating a remelting cupola which comprises charging the cupola with alternate layers of coke'and iron, discharging the air at a temperature above that of the atmosphere into the lowermost layer of coketo burn the same and to cause the resulting products of combustion to rise through subsequent alternate layers to preheat said layers, and controlling the temperature of said air to control the characteristics of the melt within the cupola.

heathen 16. A remelting cupola organization comprising a cupola, heating means for the air blast, means for introducing a portion of the products of combustion of the cupoia into the heating means, means for introducing air into the heating means to cause combustion of" the products of combustion.

17. A remelting cupola organization comprising a cupola, heating means for the air blast, means for introducing a portion of the products of combustion of the cupola into the heating means, means for introducing air into the heating means to cause combustion of the products of combustion, and means for controlling the temperature of combustion within the heating means to regulate the temperature of the air blast.

18. lin a remelting cupola organization, the combination of a cupola adapted to receive alternate charges of coke and iron, heating means "for the air blast, means for divert 'ing, a portion of the unburned products of combustion and for passing them through the heating means to heat the air blast and means for controlling the temperature of the air blast for controlling the characteristics of the melt.

19. in a remelting cupola organization the combination of a cupola adapted to receive alternate layers of cokeand iron, an air blast adapted to deliver air to the lowermost layer of coke to burn the same and whereby to cause the resultant products of combustion tolrise through the subsequent alternate layers. of coke and iron, means for preheating the air blast prior to its delivery to the lowermost layer of coke and means for regulating the temperature of the air blast for controlling the characteristics of the melt. within the cnpola.

QOJA remelting cupola organization, comprising a cupolaand a combustion preheater associated therewith, means conducting unburned gases resulting from primary combustion in the cupola to'said combustion preheater, and means conveying air of combustion from. said preheater to the zone of primary combustion in said 'cupola.

2].. A remelting cupola organization, comprising, a cupola provided with means for conducting away unburned gases of the primary combustion in the cupola, a preheater having combustion chamber connected to the means'conducting said gases from the cupola and adapted to burn said gases in said preheater, tlues arranged through said preheater for conducting the air of combustion tor the cupola to preheat it prior to its admission to the cupola.

22 A remelting cupola organization, comprising, a cupola, a preheater having a coinbustion chamber, means conducting unburned gases from the cupola to said combustion chamber, flues aranged within the preheater for the products of combustion from the combustion chamber and for the air of combustion to the cupola, said flues being arranged to cause the cupola air of combustion to be preheated through the combustion of the gases of said 'cupola.'

23. A remelting cupola organization, comprising, a cupola, a preheater associated therewith and having a combustion chamber, means for transferring unburned gases from said cupola to said combustion chamber, flues arranged in said preheater for conducting cupola air of combustion through the heater and for conducting air of combustion for the combustion .in the preheater through a zone heated by. combustion in said combustion chamber.

24. A remelting cupola organization comprising a cupola, a preheater having a combustion chamber, means for transferring unburned products of combustion from said cupola to said combustion chamber said preheater having flues for passing air' to said combustion chamber, and flues for passing air to the air blast of the cupola. and flues for the products of combustion of the combustion chamber of the preheater, said flues being constructed and arranged to preheat both the air for the cupola blast and the air for the combustion chamber of the preheater.

25. A remelting cupola organization, comprising, a cupola, a preheater having a coin- -bustion chamber, means for passing unburned gases from the cupola to said combustion chamber, said preheater having flues for the cupola air of combustion, the air of combustion of the combustion chamber of the reheater, and the products of said coinbustion, said flues being arranged to preheat air of combustion for the 'cupola and in greater amount the air of combustion for said combustion chamber. I

26.,A remelting cupola organization, com rising, a cu ola, a preheater havinga com ustioncham er, means for transferring unburned gases from said cupola to said 7 combustion chamber, said preheater having flues. for conducting air of combustion through the preheater to preheat the same and deliver it to the cupola, and means controlling the combustion in said combustion chamber. 5

27. A remelting cupola organization, com- I prising, a cupola having a zone of combustion at its bottom, a charging door thereabove, means for removing unburned gases from said cupola intermediate said zone of combustion and said charging door, and an apparatus utilizing said removed gas to preheat air of combustion delivered to the cuola.-

28. The process of operating a remelting cupola, which comprises, charging the eupola with alternatelayers of coke and iron,

tei'nate layers, and removing a portion of said products of combustion before'they pass through all of said subsequent layers.

30. The process of operating a remelting cupola, which comprises, charging the cupola with alternate layers of coke and iron, supplying preheated air to thelowermost layer of coke to burn the same, and removing a part of the product of combustion just above said lowermost layer of coke and before its contact with-subsequent layers of coke has permitted reduction of a substantial part of the carbon dioxid gas to carbon monoxid.

FREDERICK K. VIAL. GEORGE s. EVANS.

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