US2167596A - Process and apparatus for operating a primary furnace - Google Patents

Description

F. K. VIAL PROCESS AND APPARATUS FOR OPERQTING A PRIMARY FURfI ACE July 25, 1939.

Filed Dec. -2, 1937 2 Sheets-Sheet 1 F. K. VIAL July 25, 1939.

PROCESS AND APPARATUS FOR OPERATING A PRIMARY FURNACE Filed Dec. 2, 19257 2 Sheets-Sheet 2 20 through, thus permitting the maximum amount Patented Jul 25, 1939 h I 4 2,167,596

UNITED. STATES PATENT OFFICE PaocEssfANn APPARATUS FOR orEaAmG- A ranuARY FUaN cE A Frederick K. Vial, Chicago, 111., assignor to Grif- 'fln Wheel- Company, Chicago, 111., a, corporation of Massachusetts Application December 2, 1931, Serial No. 171,115 '1 Claims. (c1. ass-14) My invention relates to metal working appafer system since the purpose of the system is to ratus and the process of operating said apparatus transfer a maximum amount of the heat from and more'particularly' to such an apparatus as exhaust gases into the incoming air of combusthat generally described in my Patent No. tion, and the latter in that the cost of heat- 5 2,078,747, issued April 27, 1937. I resisting alloys is so great as to make such an 5 My invention is'directed to an improvement in" arrangement a commercial impracticability. the general type of metal melting equipment de- Accordingly, I have devised a system of heat scribed in the said Patent No. 2,078.747 wherein transfer for such equipment which will permit a pre-heater is used in combination with a meltcontinued use of the present materials, will maining cupola. I tain substantially the present heat transfer efii- 10 An object of my invention is to improve the ciency, and will permit a cost not to exceed that manner of utilizing the waste gases from the at present incurred.

cupola asa means of pre-heating the cold air A more specific object of my invention is to of combustion which is normally drawn from the provide an eflicient means of heat transfer beatmosphere. I X v Q tween incoming air of combustion and outgoing l5 It is known in the art that the most eificient hot gases in such a structpre as that described form of heat transfer between gases takes place which will at the same time permit use of cold when these gases traverse adjacent conducting air to moderate temperatures developed in critimedium, passing in opposite directions therecal areas of the pre-heater and combustion chamr. of conduction to take place between the two me- Another object of my invention is to provide diums as they travel through their respective consuch an arrangement of ducts for the cold air duits. Such an arrangement is shown in my of combustion and the hot exhaust gases in such above-mentioned Patent, w erei a structure as I have herein described as will the exhaust gases from a cupola are passed permit the use of any portion or all of said cold 5 through a series of pipes in a pre-heater while air of combustion to modify the high tempera- I, the cold air is circulated around said pipes by tures developed in critical areas thereof. a baflle construction within said heater in a Other objects, features and advantages are direction substantially opposite to that taken by comprehended by my invention as will appear in the exhaust gases. the further description and drawings formin ,8: 30

In operation certain dimculties have been enpart of this specification. countered in such a construction due to the fact In the drawingsFlgure 1 is a view in elevation that the incoming cold gases-reach a maximum of a cupola and pre-heater structure embodying temperature in the same area of the heater where my invention, a portion of said pIe heater being the outgoing exhaust gasesfrom the cupola and shown in section; 35

' the combustion chamber are also hottest. Due Figure 2 is a plan view of the structure shown to this fact the constructionof the heater at the in Figure 1; and said area issubject-to rapid deterioration with Figure 3 is a side elevation of the cupola and the result that it is impossible to maintain such 1 pre-heater structure shown in Figures 1 and 2. 40. a structure in operative condition except for a Describing this embodiment of myinvention 4o relatively short period. Means of overcoming in detail, it comprises the primary furnaces herethis difllculty have been suggested such as therin shown as re-melting cupolas 2 and 4 of the mostatically controlling the exhaust gases to such usual form supported on the base structures 6 a temperature that the sheet and tube construcand 8. Near the base the cupolas have bustle tion in the area under consideration will last a pipes I0 and I2 with the tuyere leads l4, l4 and 45 suflicient lengthof time to make the construction tuyere boxes l6, l6, comprising means for cona commercial one. Another suggested remedy is ducting the gas-to the usual tuyeres. Gases are such a construction of the pre-heater plates and conducted into the bustle pipes ill and I2 through pipes in the said area as will provide resistance the hot blast pipe [8 which forms a juncture with to the excessive temperatures which occur therethe respective bustle pipes through the gates at 50 at and it is known that such construction can 20 and 22. At a height slightly below the chargbe provided by the use of certain heat-resisting "mg door 24 the respective cupolas are surrounded alloy metals. Both of the above-mentioned remby the circular ducts 26 and 28 through which: 1 ediesare open "to objections; the former in that partially burned gases may be drawn off from it zreitwmeznmes r e peat iransthe cupolas. The circular ducts 2s and 20 have u the clean-out doors 30, 3'3 and gas outlets leading respectively into the vertical gas ducts 32 and 34 having the clean-out doors 33, 33, both of said ducts discharging into the auxiliary combustion chamber 36. Air for the combustion chamber 35 is withdrawn from the cold blast pipe 60 at the gate 31 and delivered through the ducts 4i and 43 into the larger ducts 32 and 34, respectively, as at 45 and 41 (Figure 2). From the combustion chamber 36 the hot gases pass into the distributing chamber 38 and from the distributing chamber into the body portion 39 of the pre-heater in a downward direction through the multiplicity of fiues or conduits 40, 40 into the transfer chamber 42 and thence through the duct 44",ilil20 the transfer chamber 46 from which they pass in an upward direction through the flues 40, 4D in the body portion 48 of the pre-heater and thus into the exhaust chamber 50. The hot gases are discharged from the exhaust chamber 50 through the exhaust pipe 52 by means of the exhauster 54 into the exhaust stack 56, whence they are discharged into the open air. Support for the pre-heater and for the combustion chamber is provided by the platform indicated at 35 and for the exhauster and the exhaust stack by the platform indicated at 53. The exhaust chamber 50 as well asgthe distributing chamber 38 and the transfer chambers 42 and 46 have the usual clean-out doors 49, 49.

The cold air of combustion is drawn in from the atmosphere by means of the blower indicated diagrammatically at 58 (Figure 1) and is forced through the cold blast pipe 60 and the gate 6| into the upper part of the pre-heater body 39 as at 62, saidupper part of this portion of the preheater being separated from the remainder thereof by the horizontal partition plate 63 which is perforated to accommodate the vertically arranged flues 40, 40. The partition plate 63 thus 4 divides the body portion 39 of the pro-heater into upper and lower compartments and the incoming air from the cold blast pipe 60 is discharged through the said upper compartment into the duct 84, whence it passes into the upper end of the pre-heater body 48 as at 66. From the upper area. of the pre-heater body "the cold blast is directed alternately back and forth in horizontal directions by the baffle plates 61, .61 and around the fines 40, 40 into the lower area thereof, whence it is discharged through the horizontal duct 10 into the lower area of the pre-heater body 39 through which it is directed back and forth in horizontal direct ons by the baflle plates 61, 81 and thence thro h the opening I4 into the hot .blast pipe II. The path 'oi' this cold blast from the gate 6| through the two portions of the pre-heat'er is shown by the continuous arrow indicated at various points as l2, l2.

It will thus be seen that by separating a relatively small upper portion of the pre-heater body 39 from theremainder thereof by the partition plate 63 and conducting therethrough the cold blast or a part thereof, I have provided a means of protection for the pipes or flues 40, 40 and for the structural plates of the distributing chamber and of the heater body in the vicinity where the hottest gases enter the pre-heater from the combustion chamber 36. By this modification I have provided at this critical juncture of the structure a means of controlling the temperature of said flues and plates and preventing their rapid destruction or disintegration by the excessive temperature otherwise prevailing. It willalso be observed that I have faciliated this arrangement by constructing the pre-heater in two portions so arranged with respect to each other that the hot gases pass in a vertically downward direction through one portion and in a vertically upward 5 direction through the other portion, whereby I may efllciently provide entrance for the cold blast at one end of the pre heater as at 66 and an exhaust at the other end of the pro-heater as at 14 while at the same time utilizing the cold blast as a means of moderating the temperatures to which the iiues and plates are subjected in that area of the pre-heater where the hot gases enter it. By this construction I have an arrangement wherein the direction of flow of the. 15 cold blast through the pre-heater is counterwise to the direction of flow of the hot blast through substantially the entire length of the pre-heater, thus securing the most eflicient heat transfer therebetween while at the same time I have uti- 20 lized the cold blast as a means of moderating the high temperatures of the before-mentioned fiues and plates in the most critical area of the preheater construction as above described.

It may be further noted that the cold blast duct 60 is divided as at 16' (Figure 2) into two legs, one of which leads to the gate 6! as already described and the other of which is in the form of a by-pass I8 around the pre-heater body 39 to the gate whence cold air may be discharged 30 directly into the upper part of the body portion 48 of the pre-heater as at 82. By thus dividing the cold blast I may at will modify the proportion which is carried through the by-pass I8 directly into the upper area of the pre-heater body 48 as .35 compared with the proportion of the cold blast which isfirst led through the upper portion of the pre-heater body 39 as a means of modifying the temperatures therein before being led through the duct 64 into the said upper area of the preheater body 48.

By this compact arrangement of parts and particularly the division of the pre-heater into two vertical sections side by side, with a common combustion chamber serving both, and the dual cupolas operated-in conjunction therewith, I have devised a most emcient arrangement by which adequate protection is afforded that portion of the pre-heater which has heretofore been most susceptible to quick deterioration. My exrience has indicated that with structures of his specific type it is desirable to have by far the greater portion or all of the cold blast directed through the independent chamber at the top of the pre-heater body 38, thus using it as a cooling medium for the critically high temperatures developed in that area. Nevertheless, it will be apparent to those skilled in the art that under certain conditions it may. be desirable to by-pass a portion of said cold air blast around so the pre-heater body 39 directly into the upper portion of the pre-heater body 43. By the arrangement I have devised, the most eflicie t division of this cold blast is readily provided or by control of the gates at El and 80 respectively. 65

be limited by the exact embodiment of the device shown, which is merely by way of ilustration and not limitation, as various andother forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

I claim:

1. In a heat exchanger, a pre-heater having adjacent hot and cold ends'and interlaced passageways therebetween for conducting hot and cold gasesrespectively, said cold gas passageway comprising an entrance to the cold end of said p e-heater through an independent passageway at the hot end thereof, and an exit adjacent said entrance at said hot end.

2. In a combustion system a primary combustion furnace, an auxiliary combustion chamber, a pre-heater having a narrow zone at the hot end divided from the main body thereof, means for conducting atmospheric air through said zone directly to the opposite end of said pre-heater and in a. given direction therethrough and thence into said primary combustion furnace as a means of combustion therefor, and means for withdrawing partially burned gases from said primary furnace and conducting them to said auxiliary chamber and for conducting the gases from said chamber through the length of said pre-heater in a direction reverse to that first mentioned, said pre-heater being so constructed and arranged as to permit the hot and cold ends to be adjacent.

3. In a heat transfer system, a pre-heater having adjacent hot and cold ends, an independent zone at the hot end thereof, means for conducting a cold blast through said zone directly to the cold end of said pre-heater and in a given direction through substanaially the length of said pre-heater, and means for conducting hot gases through the length of said pre-heater in a direction reverse to that first mentioned, whereby protection is afforded the structure at the hot end of said pre-heater while maintaining the most eflicient means of heat transfer between said cold blast and hot gases.

4. In a combustion system a pre-heater having adjacent hot and coldends, an independent zone at one end and means for conducting air through said zone directly to the cold end of said preheater and through said pre-he'ater in a given direction, and nieans for conducting hot gases through the length of said pre-heater in a direction reverse to that first mentioned, whereby said air and said hot gases traverse said pre-heater in reverse directions for substantially the length thereof and afiord maximum efficiency of heat transfer therebetween while at the same time said air serves to moderate the maximum temperatures at the hot end of said pre-heater.

5. The method of heating a gas by passing a hot gas and the gas to be heated over opposite sides of a heat transfer means in the form of a pro-heater comprising passing the gas to be heated through that portion of the pre-heater where the hot gas enters directly into the adjacent portion of the pre-heater where the hot gas is discharged and thereafter passing it in contact with intermediate portions of said preheater through substantially the length thereof in a direction reverse to that traversed by hot gas.

6. A heat exchanger in the form of a pre-heater having adjacent hot and coldends, means for passing the hot gases through said pre-heater in a given direction, means conducting atmospheric air through said pre-heater adjacent the hot end thereof directly into the cold end, and means for conducting said air through substantially the length of said pre-heater in a direction reverse to that traversed by said hot gases, whereby said air serves to moderate the temperatures at the hot end of said pre-heater while said parts are so constructed and arranged as to permit eflicient heat transfer between said air and said gases for substantially the length of said pre-heater.

'7. In a heat exchanger, a pre-heater having adjacent hot and cold ends and interlaced passageways therebetween for conducting hot and cold gases respectively, said cold gas passageway comprising an entrance through the hot end of said pre -heater to the cold end thereof, and an exit adjacent said entrance at said hot end.

FREDERICK K. VIAL.

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