US3533522A - Furnace top distributor for shaft furnace,particularly for blast furnaces - Google Patents

Description

NORBERT'INGEMAR SCHNEIDER ULARLY Oct. 13, 1970 FURNACE TOP DISTRIBUTOR FOR SHAFT FURNACE, PARTIC FOR BLAST FURNACES Filed March 6, 1969 1 4 /20 I gJ nited States Patent Ofice 3,533,522 Patented Oct. 13, 1970 3,533,522 FURNACE TOP DISTRIBUTOR FOR SHAFT FUR- NACE, PARTICULARLY FOR BLAST FURNACES Norbert-Ingemar Schneider, Berlin, Germany, assignor to Demag Aktiengesellschaft, Duisburg, Germany Filed Mar. 6, 1969, Ser. No. 804,898 Claims priority, application Germany, Mar. 8, 1968, 1,608,303 Int. Cl. F27b 11/12 US. Cl. 214-35 7 Claims ABSTRACT OF THE DISCLOSURE A furnace charging device for shaft furnaces, particularly blast furnaces, includes a feed conduit or funnel which is arranged between two separate sluice chambers each of which has a charging connection to the feed conduit which may be periodically opened and closed without losing the furnace pressure. The feed conduit carries an internal rotary distributor having a lower eccentric opening. The distributor is rotated by an external drive mechanism mounted on a pressure-tight fitting between the feed conduit and the furance head.

SUMMARY OF THE INVENTION This invention relates, in general, to the construction of furnace charging devices and, in particular, to a new and useful furnace charger for high pressure furnaces which includes a rotary distributor which is mounted in a pressure fitting between a feed conduit and the furance head.

In order to increase the output of blast furnaces, it has been proposed in recent times to operate at increased pressure at the top charging end of the furnace and to use pellets. The pressure increase is connected with certain difficulties and the distribution of the material to be charged requires particular measures. According to one previously proposed method, the material is distributed on the charging surface in a damming manner. Generally, however, blast furnaces which are presently in operation have furnace top distributors which operate with the usual pouring methods.

A furnace top distributor is known in which the material to be charged is fed by means of a rotary distributor and wherein a sluice chamber is present for sealing the furnace space. The material to be charged which is originally supplied to one circumferential area of the charging opening is distributed by means of a rotary mechanism to the distributor device proper. This distributor device is in the form of a sluice chamber and has an upper and lower filling funnel or hopper, each having a distributor bell. This distributing device which is generally known as a McKee double bell distributor has to perform two functions, i.e. operate as a sluice chamber and also as a distributor.

The sealing of the furnace space pressure by means of the double bell distributor may be sufiicient for lower pressures. The life of the sealing surfaces was generally considered to be within tolerable limits. The prevailing temperatures and the wear constitute a considerable stress on the life of the bells. For this reason, higher charging gas pressures could not be used with such double bell distributors. At a diameter of several meters, heat distortion is very much noticeable. The heat distortion, in turn, causes untight areas at the sealing seats. The material which flows over the bell erodes the sealing seat armor and, of course, rapidly increases the leakage.

The distribution of the material to be charged by means of an upper bell and filling funnel and a lower bell and distributor key, leads to concentric rings of poured material of a cone-like cross section. Such a deposition of material takes place in the sluice chamber between the two bells and in the furnace space. Another type of distribution is only very imprecise and not very secure.

A better construction of such a sluice chamber is disclosed in Journal of Metals, February 1966, pages 2311f. The sluice chamber distributors are situated in the open position outside the path of the material to be charged, in the same way as their sealing seats. Their diameter amounts only to a fraction of the dimensions of the bells. Further, in this range, lower temperatures prevail. Further, due to pressure equalization, it is possible to keep away the dangerous charging dust from the sluice distributors. This sluice chamber thus is not subject to the stresses and wear of other constructions of this nature.

The function of the distributor device, however, is fulfilled as in the prior art constructions by a pair of known bells of large diameter which cooperate with funnel keys. The high construction of the superposed distributor bells which are at relatively great spacing leads to a disadvantageously large failing height of the material to be charged. In other words, the material has to travel a long path. However, in respect to many types of furnace burdens, mechanical stresses are to be prevented. There is a tendency to keep the amount of fine-grained material in the blast furnaces as small as possible. The known furnace top distributor moveover does not meet the requirement in respect to precise deposition of the individual charges onto the respective surface. Further, the suspension of the bell at interengaging coaxial rods causes a division of the flow of charged material and thus an inaccurate deposition. Such bell rods, due to wear, have to be additionally reinforced by armor in order to be able to withstand and exert resistance toward the constantly flowing material of greater hardness.

The present invention overcomes these disadvantages by combining a sluice chamber which can withstand high pressures with a distributing device, the distributing device being suitable for distributng furance burdens of different characteristics and in a high output operation and being capable of compensating any irregularity of the furnace operation as it occurs in practice.

In respect to furnaces operating under high pressure conditions, an enlarged charging surface is present. This is so particularly in respect to furnaces of novel construction which have a large diameter. Such an enlarged charging surface, of course, increases the difficulty of distributing the material as uniformly as possible. In considering this problem, it has to be considered that the means or members of the distributing device are not permitted to be arranged in such a manner that after a short period untight or unsealed areas would lead to a pressure drop within the furnace space. In accordance with the invention, a desirable furnace top distributing device can be created which includes a rotary distributor mounted within a casing which is under a high furnace space pressure and which is drivable from the outside. The casing or housing forms the connection between the furnace space and the sluice chamber from which the charging material is discharged under the furnace spaced pressure into the rotary distributor.

The sluice chamber without any auxiliary means would not be able to distribute the material or it could only distribute it on concentric circles as is the case in double bell distributors. Short falling heights for the material and prevention of substantial untight areas significantly facilitate proper operation under high pressure conditions. In the interest of a uniform gasification, damage to furnace burdens which are pretreated and contain a high amount of iron is to be prevented. However, even if during the operation any unforeseeable irregularities in the gasification should result, it is possible to equalize or compensate the irregularities by properly adjusting the charging. The invention thus combines several advantages.

In order to have a long life for a high pressure furnace top distributor arrangement, the accommodation of the individual parts is a decisive factor. For this purpose, the invention provides drive elements for the rotary distributor which are accommodated in an annular space which is in connection with the pressure casing. The annular space is under the counter-pressure of purified charging gas. Any gas that may flow off through the guide mounting of the drive shaft does not reduce the pressure of the furnace space, but consists of counter-pressure gas. The dust which is contained in ordinary charging gas can be kept away from transmission parts and thus does not cause any wear. Purified charging gas emanates from a cooling device and possesses accordingly a lower temperature. If necessary, this gas contributes to a cooling of the driving parts.

Another improvement of the invention provides that the rotary distributor is constructed as a cone-shaped funnel with an exit opening which is eccentric to the rotary axis. The pressure casing forms a short structural unit together with the rotary funnel between the furnace head and the sluice chamber, which can be exchanged relatively quickly. However, such a funnel which forms the pouring cross section has the advantage that it may be provided with a wear-resistant layer which does not cause any disturbance or obstacles in the flow of the material. Such a passage is suitable as guide to prevent an undesired expansion of the parts of the material which have uneven particle size. Although blast furnace operators attempt to maintain a very narrow range of grain sizes in the preparation of the charges, it is unavoidable that larger parts strike the charging surface with a higher velocity, and thus have distinct falling curves. If the grains slide for a long time with the same speed, a premature demixing can be prevented.

Although a distribution of the *material for large charging surfaces is possible in accordance with the invention, a. protection for the furnace wall may be necessary if there is an unfavorable ratio of charging diameter to the diameter of the upper furnace portion. Further, if the furnace cross section is abnormally large, small particle material may have a tendency to roll toward the interior. The invention prevents such errors by providing one device for the distributing of the charging material onto the charging surface at a location below the rotary distributor and a further device in the form of a single bell which cooperates with a charging key. This construction thus constitutes a favorable buffering device and, in rapid procedures, a sufficiently large amount of charge or coke will thus be available while the sluice chambers are in the process of being filled.

It is particularly difficult to perform repairs at blast furnaces which cannot be shut down. Exiting gases thus make it impossible to work without gas masks. However, with blast furnaces operating under high pressures, an escape of the gases cannot be permitted because of the resulting pressure drop. If in such furnaces portions of the charging devices are to be replaced, extremely great difiiculties have to be overcome. The invention shows a way for overcoming this difficulty without having to suffer a pressure loss. Between the pressure casing and the furnace head there is provided an expansion member and the furnace space is closable in pressure-tight manner by means of a slide or the like situated below the expansion member flange. This provides a liftability of the charging device at the area of the expansion member which causes the required yieldability. Without opening the furnace, displacement of the sealing element above the charging shaft is thus possible. After closing has been accomplished, the disassembly operation can be performed without being disturbed by the gas and. parts of the charging device can be replaced.

Accordingly, it is an object of the invention to provide a charging device, particularly for a blast furnace, which operates at relatively high pressures which includes a rotary distributor mounted within a feed conduit and driven externally by a drive mechanism mounted on a pressure fitting around the feed conduit.

A further object of the invention is to provide a charging device for a furnace which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference is had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING The single figure is a vertical section through a furnace top distributing device constructed in accordance with the invention and taken along the plane of the furnace center axis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, in particular, the invention embodied therein comprises a charging device which is connected at its upper end to supply containers or bunkers (not shown) which feed through controlled pressure fittings into the pressure-tight chambers or sluices 10 and '11. The charging material is delivered through sealing flaps 1 and 2 which can be operated successively or at the same time, into a centrally arranged feed conduit or funnel 3. A casing 4, as well as a surrounding pressure fitting or casing 5 which is suspended thereon and which carries a rotary distributor 6 engages a charging platform 7. The connection between a furnace head 8 and the pressure-tight funnel 3 includes an expansion member or seal 9. The funnel 3 and the rotary distributor 6 formed as a continuation of the funnel are maintained at the pressure of the furnace space 12.

The rotary distributor 6 carries on its outer jacket 13, the drive wheel or gear 14 of a drive whose pinion 15 is mounted on a drive shaft 16. The drive shaft 16 is rotated by a drive motor (not shown) and it penetrates the pressure casing 5 within a sealing packing or washer 17. Gear 14 and pinion 15 are accommodated in an annular space 18 of the pressure casing 5. The annular space 18 is protected against penetration of charging dust by a gliding ring seal 19. However, in order to make the rotary mounting 20 safe from penetration of dust, purified charging gas or another pressure gas is blown through the compressed gas connections 21 and 22. The mounting of the rotary distributor 6 is provided with a labyrinth packing 23.

Advantageously, the expansion member 9 is provided with an additional guide or protection ring 24 so that no damage can occur. Below the member 9, there is provided a slide 33. The rotary distributor '6 is suspended in a manner that permits its quick exchange and free expansion under the heat action of the furnace can take place. This is an additional advantage of the invention. The compressed gas which is introduced into the annular space 18 is therefore very beneficial and prevents penetration of dust toward both sides in an axial direction.

In the embodiment shown, the rotary distributor 6 is constructed as a funnel with eccentrically arranged exit opening 25. If necessary, this outlet opening may be displaced further downwardly.

The rotary distributor 6 forms a free channel for the passage of the material into the furnace space 12. It is also possible to guide through the rotary distributor 6 a holding device if the latter is situated in the eccentric channel 26 in such a manner that the flow of the material is not affected.

The embodiment indicated includes a suspension for a distributor bell 27 which includes a traverse member 28 which is connected to the bell 27 at the bolt joint 29. At the ends of the traverse member 28, there are provided holding rods 31 which extend upwardly in sleeve or pressure ducts 32. The ducts 32 are in connection with the furnace space 12 and the upper part of the funnel 3 and are maintained at the same pressure as the furnace space.

What is claimed is:

1. A furnace charging device, comprising a furnace charge mouth, a sealed feed conduit connected at its lower end to said furnace charge mouth and having connection means adapted to be connected periodically to a charge supply, a rotary distributor having a lower discharge opening and being rotatably mounted within said feed conduit to receive the charge material and to discharge it through the opening, a pressure fitting surrounding said distributor, and a drive mechanism for rotating said distributor located on the exterior of said feed conduit and connected through said pressure fitting to drive said distributor.

' 2. A furnace charging device, according to claim -1, wherein said pressure fitting comprises an annular member forming a downward continuation of said feed conduit, said annular member defining an annular pressure space around said feed conduit, said drive mechanism driving elements located within said pressure space, said pressure space being adapted to receive a counter-pressure to prevent outflow of gas through the driving connections. 3. A furnace charging device, according to claim 2,

wherein said pressure space contains purified charging gas.

4. -A furnace charging device, according to claim 1, wherein said distributor comprises a cone-shaped funnel having an exit opening eccentric to its rotary axis.

5. A furnace charging device, according to claim 1, wherein said furnace charge mouth comprises a key housing having an opening at its lower end, and a bell-shaped distributor arranged within the opening of said charge mouth in a position for distributing the material to be charged therearound into the furnace.

6. A furnace charging device, according to claim 1, wherein said feed conduit includes a tubular extension forming said pressure fitting extending down to said furnace mouth, a tubular flexible seal extending between said furnace mouth and said tubular extension and sealing said tubular extension to said furnace mouth.

7. A furnace charging device, according to claim 6, including a slide plate having an opening arranged in said tubular extension and located to provide a continuous through opening in said feed conduit to said furnace mouth, said slide plate being displaceable to close the opening between said feed conduit and said furnace mouth.

References Cited UNITED STATES PATENTS ROBERT G. SHERIDAN, Primary Examiner US. Cl. X.R. 266-27

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