US1555423A - Smelting furnace with coal-dust firing - Google Patents

Description

Sept. 29, 1925.' H. LscHE l SMEL'VIING FURNACE WITH COAL DUST FIRING Filed July 23, 2.1925 2 Sheets-Sheet l wif/fesses 1,555,423 H. LSCHE- SMELTING FURNACE WITH COAL DUST FIRING v Filed July 23. 1923 .2 Sheets-Shoe?.v 2

I l l I I l l I "l 1 Il fnveno Sept. 29, 1925.

and useful Improvements in Smelting Fur-` Patented Sept. 29, 1925.

HANNS IiSCHE, 0F COLOGNE-MULEIM, GERMANY.

SMELTING FRNACE WITH COAL-DUST .FIING.

Application le. July 23, 1923. Serial No. 653,168.

To all whom t 'may come/m:

Be itknown that I, HANNs LSCHE, residing 'at Cologne-Mulheim, `State of Prussia, Germany, have invented certain new naces with Coal-Dust Firing, of which the following is a specification. c

This invention relates to smelting furnaces and, more particularly, to furnaces for smelting steel and iron of the open hearth type with which coal dust irings are used instead of the gas firings or partial gas firings mostly in use with such furnaces.

The invention has for its primary object to` provide an open hearth furnace of the kind stated with which the point of injection for the powdered fuel is arranged, in the form of one or more injecting nozzles, in a perforation of the crown of lthe furnace, the arrangement being preferably so as. to cause the coal dust flame, whichv is generated in the interior of the furnace in front of themouths of the nozzles, to rush d )wn vertically onto thesmelting charge or bath resting on the hearth below. Owing to this particular arrangement, the highest generation of heat will take place in the middle of the furnace space above the lowermost point ofthe smelting bath and, at the same time, the largest part of the very intensive radiation heat will Vbe transmitted directly to the smelting charge without beingn first transferred to the furnace wall/s. It is thereby rendered possible to melt materials of high melting points and to make considerable savings 1n fuel at the same time providing for a higher durability of the masonry of the furnace.

Another object of the invention is to improve with furnaces of the present kind the uniformity o'f the action of the heat on the several points of the hearth, this being attained` by a novel construction of the re generators used fortpreheating the .secondary air as well as of the channels 1n com- 4 munication with the regenerators.

With these and other ends 1n view the invention consists in the construction, arrangement and combination of parts such as described hereinafter and shown in lthe-'accompanying drawing, in which:

Fig. 1 is a view of the furnace and firing,

partly in longitudinal section and partly inv elevation; p

Fig. 2 is a horizontal section along the line II-II of Fig. 1;

Fig. 3 is a horizontal section along theA line III-III of Fig. 1; and

Fig. 4 isa vertical` section of the reversi ing device for controlling the regenerator chambers.

The inner space of the furnace which is surrounded by the longitudinal walls 1 and the end walls 2 which are shorter than the walls 1, is covered in the -usual way by a crown 3 consisting of refractoryr bricks.` The bottom ofthe furnace space is rmed by the hearth 4 which serves to receive the smelting charge' andthe surface of which is likewise lined with a layer of a suitable refracy tory material. v

The base of the furnace comprises four chambers 5, 6, 7, 8 which are cross-wise symmetrical and which contain the checker `work 9 of the regenerators consisting of refractory bricks. Each of the regenerator chambers is in connection with the inner spaceA of the furnace by means of a channel 10, 11,

.12 and 13, respectively, which extends vertically upwards near the middle portion of the side walls 1 up to a point underneath the crown 3. f v

The channels 10, 11, 12, 13 open into the furnace space by tapering ports 14 which are preferably inclined in a downward direction. lThere are, besides, provided four vertical channels 16, 17, 18 and 19, which open into the furnace space at 15 closelyl above the hearth and the lower ends of which are in communication with the regenerator chambers 5, 6, 7 and 8. Below the checker works 9 the chambers 5, 6, 7, 8 are provided each with a passage 20, 21, 22, 23 which are connected cross-wise by two and two with channels 24 and 25, respectively,

`leading to the reversing valve 26 into which they open by two upwardl directed ports 28, 29.

Situated between t e two ports 28, s

29 is the mouth V30 of the flue 31 which is in constant communication with the chimi ney 32. 33 is a lbutterfly valve mounted for rotation around a-horizontal axis above the ` ports 28, 29, 30V and adapted to establish communication between one of the ports 28 or 29 and the flue mouth 30 at the same time closing the .same with respect to the valve chamber 26 which is open to the atmosphere, while the other of the two, ports 28, 29 is placedinto communication with the atmosphere.

` i-The firing-of the 'furnace consists of a coal dust injecting nozzle 34 which is mountlll ' to convey the coal dust through the piping is fed to the blower 37 from a bunker 40 through a vertical pipe 39. rllhe quantity of the coal dust to be supplied in the unit of time is controlled by any of the wellknown measuring appliances which may be a rotary valve or the like rotated by a sprocket wheel 4l at a speed corresponding to the quantity of coal dust to be supplied.

'l rlhis sprocket wheel as well as another sprocket wheel 42, which is arranged at the lower end of the funnel-shaped outlet of the bunker 40 and whichserves to operate a stirring mechanism arranged in the interior of the bunker 40 and designed yto secure the uniformity of the coal dust supply, are driven by a common sprocket chain 43 which is moved by a sprocket wheel 44.-

Rotation is imparted to the latter by the driving shaft of the blower 37 through the intermediary of a worm wheel 45 and a worm 46 as well as two pulleys 47, 48 and a driving belt 49. rlhe driving speed of the sprocket wheel 44 may be controlled by the intercalation of any suitable means.

During the working of the furnace, the combustion of the coal dust current introduced into the furnace along with a certain quantity of air by the action of the blower 37 will take place in the middle of the furnace space, while preheated secondary air flows in at the same time through two diagonally opposite ports 14 from the two respective regenerator chambers, whereby a complete combustion is secured. Owing to the downwardly directed movement of the coal dust conveying air-current and the downwardly inclined arrangement of the inlet ports 14, the combustion gases will be blown onto the smelting charge resting on the hearth and thus directly transmit to the same a large part of their heat, without the free development of the flame being in any way impeded. a

In the position vof the buttery valve 33 as shown in Fig. 4, the channel 24 is in communication with the yiue 31. The two regenerator -chambers 5 and 7 connected to the channel 24 are therefore subjected to the action of the chimney draught, so that the combustion gases will be drawn olf from the furnace space at diagonally opposite points through the channels 16, 18 w ch are in communication with the said regenerator chambers 5 and 7. At the Vsame time, the two other regenerator chambers 6, 8 are 1n communication with the atmosphere through the connecting channel 25 and its open outlet port 28. y In the kascending channels 11, 13 which are in connection with those two chambers 6, 8, a strong ascension is produced which will cause the heated air to flow intov the combustion space of the furnace. rlfhe ascending action draws in fresh air from the atmosphere through the channel 25, this air being heated in the checker work of the two regenerator chambers 6, 8 and caused to enter the combustion space as preheated secondary air through the diagonally opposite outlet ports 14 as mentioned before. j

llf, after a certain time, the two regenerator chambers v6, 8 have cooled down to a certain degree, while the checker work of the two other regenerator chambers 5, have been correspondingly heated by the combustion gases which are passing to the chimney, the butterfly valve 33 will be reversed so as to'place the channel 25 into communication with the flue 31 and the channel 24 into communication with the atmosphere. Fresh air will then flow through the twoA regenerator ehambers and 7, ascend in the channels 10 and 12 and enter the combustion space by the Ipair of diagonally opposite ports 14 associated with such regenerators, while the combustion gases will pass from the combustion space through the channels 17 and 19 down into the two regeneratorchambers 6, 8, from which they flow through the channel 25'to the Hue 31 and chimney 3.2.

It is to be understood that instead of one injecting nozzle 34, there may be provided a plurality of such nozzles. In such case, the nozzles are preferably arranged in a plurality of separate perforations of the crown close beside one another near the middle of the furnace or.at more or lesslarge distances in one or more longitudinal rows. rlhe nozzles 'may then be directed to` the smelting charge at afmore or less large inclination. Besides, the inlet ports for the preheated secondary' air may be arranged in the furnace crown instead of in the side f walls.

Having thus described my invention, what l claim as new and desire to secure by Letters-Patent, is :--l f. y

1. A smelting furnace including a smelting space having a perforation in the crown thereof, a coal dust ring and a nozzle having its inlet mounted in said perforation for injecting the powdered ing space. L

2. A smelting furnace comprising a coal dust ring,` a perforation in the crownI of the furnace above the' hearth and a vertical y coal dust injecting nozzle mounted in the said perforation.

3. A smelting furnace comprising a coal .l I I V:fuel into said smeltv los dustfiring, means for injecting the coal dust into the combustion space of the furnace, channels for supplying secondary air to the combustion space and channels for leadinged the gases of combustion from the combustion space, the first-mentioned channels being 'arranged so as to open into the combustion space at the opposite longitudinal side-walls of the furnace and the secondly mentioned channels being arranged so as to open into the combustion space at the opposite end-walls of the furnace.

4. In a smelting furnace comprising a coal dust firing, a perforation in the crown of the furnace, a vertical coal dust injecting nozzle in said perforation, channels for supplying secondary air to the combustion space of the furnace arranged so as to open into said space at the opposite side-walls of the furnace, and channels for leading-off the gases of combustion from the combustion space arranged -so as to open into the same at the opposite end-walls of the furnace.

5. In a smelting furnace comprising a combustion space and a coal dust firing, a perforation in the crown of the furnace, fuel injecting means mounted in the said perforation, vfour regenerator chambers arranged crosswise underneath the combustion space, vertical channels arranged to connect the combustion space 'at four diagonally opposite corners with the regenerator chambers and adapted to lead-off the gases of combustion, and four other channels between the regenerator chambers and the combustion space designed to supply the heated secondary air and arranged to open into the combustion space through the side-walls of the furnace at points hlgher than the first mentioned channels.

6. In a smelting furnace comprising a combustion space and a coal dust firing, a perforation in the crown of the furnace, fuel injecting means mounted in the said perforation,^ four regenerator chambers arranged crosswise underneath the combustion space, a plurality of connecting channels between the combustion space and the regenerator chambers, some of the channels being designed to supplythe secondary air and some of them being `designed to lead-off the gases of combustion, and channels for connecting the diagonally opposite regenerator chambers by two and two with` a re- ,Versing member adapted to connect these channels alternately either with. the atmosphere or with the flue of the ehlmney.

signature.

\ In testimony, whereof I have aiiixed my`

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