EP0011673B1

EP0011673B1 - Coke oven loading apparatus

Info

Publication number: EP0011673B1
Application number: EP79102124A
Authority: EP
Inventors: Aldo Rossello; Riccardo Bianco; Benvenuto Biggi; Tullio Bracco; Francesco Costa; Angelo Ghersi
Original assignee: ITALIANA COKE SpA
Current assignee: ITALIANA COKE S.P.A.
Priority date: 1978-11-27
Filing date: 1979-06-26
Publication date: 1984-01-25
Also published as: IT1100766B; ES482536A1; YU178779A; IE791250L; DE2966576D1; IE48906B1; DK477079A; EP0011673A1; IT7830223A0

Description

The present invention relates to apparatus for loading coke ovens.
More specifically, the invention relates to apparatus which permits the loading of coke ovens with finely sub-divided coal having moisture content up to 15%, under extremely safe conditions with respect to ecological protection of the working environment.
As is known, coke ovens in industrial systems are arranged in parallel row gangs, and coal loading apparatus comprising a series of hoppers, corresponding in number to the number of oven loading apertures, mounted on a carriage movable on rails is employed for loading the ovens. The hoppers are aligned with the individual oven loading apertures, and after having removed the individual plug elements from the loading apertures, which may or may not be affected automatically, and having lowered a projection, with which each hopper is provided, in order to form a continuous path between each hopper and the associated oven, the coal is directly discharged, by gravity or any other suitable means, into the interior of the oven at a very high speed and in a continuous and even manner.
The main disadvantages involved in loading coke ovens with the known oven loading apparatus are the high atmospheric pollution and bad working conditions due to the escape of gases and dust during these operations.
In fact, the coal which is introduced rapidly into the hot oven causes displacement from the oven of an equivalent volume of hot air which, upon escaping, also entrains a certain quantity of coal dust.
Moreover, the freshly introduced coal, upon contacting the heated oven walls, immediately releases a large quantity of gas which in turn escapes from the oven loading apertures and expansion columns, thereby entraining a further amount of coal dust.
Several processes have been studied and tested, seeking to eliminate or at least reduce this gas and dust emission during the oven loading operation, but none of these have given satisfactory results.
Thus, for example, one process tested consists of creating a gas-tight seal between the loading hoppers and the oven loading apertures and, by means of suction devices, drawing nearly all of the gas evolved from the chamber through ducts, burning this gas and finally settling, by means of an atomized water jet, the fumes and ashes which are the products of this combustion.
This process, however, has the disadvantage that, under certain conditions, an explosive gas is formed which may explode and damage the system, and which in any case constitutes a danger for the loading operator.
Moreover, the water treatment causes suspension of acid liquids to form due to the presence of sulphur dioxide in the discharging fumes; these aqueous acid suspensions cause corrosion of the structure of the plant with which they inevitably come into contant.
Another known method, which has attracted a certain amount of practical interest, consists of using oven loading apparatus hermetically sealed to the oven-loading apertures, and extracting the gas and dust directly from the barrel by suction. This suction is obtained by superheated steam injected at a pressure of 12-14 atmospheres by means of an ejector connected to the barrel. The adoption of this process, however, requires a system for balancing and adjusting the pressures in all the ovens adjacent to that being loaded, and in the barrel.
In fact, due to an anomalous pressure increase in the barrel during the injection of superheated steam, gases leak from the so-called "weak points" of all other ovens of the gang, which are in different distillation stages. This problem is particularly acute in the case of pre-existing coke oven gangs, where the auxiliary systems have not been made for the performance of this process and where the volume of the barrel and the gas-tightness of the doors and expansion columns are rather inadequate. Consequently, in pre-existing oven gangs, atmospheric pollution by gas and dust during the loading operations seriously deteriorates the working environment of the oven loading workers.
From DE-C-693043 it is known an apparatus for loading coke ovens provided with loading apertures. The disclosed apparatus comprises movably mounted hoppers, a loading funnel at the outlet end of each hopper having means to ensure a gas-tight seal between the hopper outlet and the loading aperture of a coke oven, and suction means for removing gas and dust evolved during loading of the oven. This apparatus, however, does not solve the problems concerning the atmospheric pollution. In fact, the coal which is introduced rapidly into the hot oven causes a rapid displacement from the oven of an equivalent volume of gas and dust which leak from the so called "weak points" of all the other ovens of the gang which are in different distillation stages. This problem is particularly acute in the case of pre-existing ovens.
GB-A-163245 discloses a coke oven loading apparatus provided with a filling member comprising a stationary element "G" which is conical in form and a lower vertically adjustable element "GA" which is also conical in form and telescopes with element "G" so as to put into the hoppers a significant and substantial variation in the volume of coal to be filled. The main disadvantages involved in loading coke ovens with this apparatus are the high atmospheric pollution and the bad working conditions due to the high escape of gases and dust during the loading operations. The same disadvantages occur by using the apparatuses disclosed in the U.S. Patent No. 1,885,191 in which an oven (A') being charged is connected by a bridge vent tube (E) to an adjacent empty oven (N), or by using the coke furnace loading device disclosed in U.S. Patent No. 3,576,263 which is provided with a movable loading funnel-shaped part 31 connected to the charging bunker 1.
Thus, the object of the present invention is to provide improved apparatus for loading coal into coke ovens, which permits the problem of atmospheric pollution to be solved, especially in the case of pre-existing ovens.
This object is achieved by improved apparatus for loading coke ovens arranged in parallel row gangs and provided with loading apertures, the apparatus comprising a plurality of movably mounted hoppers, a loading funnel at the outlet end of each hopper having means to ensure a gas-tight seal between the hopper outlet and the loading aperture of a coke oven, and suction means for removing gas and dust evolved during loading of the oven, characterized in that at the inlet end of each hopper there is provided a loading shutter element of frustoconical form and variable height for connecting the hopper inlet to a coal containing silo and controlling the amount of coal delivered to the hopper, in that the means ensuring a gas-tight seal comprise a coupling sealing ring and a closure ball valve and in that the suction means comprises a bridge collector tube connecting an opening in an adjacent oven which is maintained at low pressure by a fluid injecting device at the top of the riser column thereof.
The improved apparatus of the present invention is furthermore provided with a driving cab, located on the main floor of the support structure. This driving cab preferably extends along the whole length of the apparatus, and is provided with a pressurisation system for preventing the entry of dust, and an air conditioning system.
During the whole loading stage, carried out by the present improved apparatus, the conveying of the evolved gases towards the riser column is facilitated by a low pressure condition in the upper part of the two ovens, and by their connection together by means of the bridge collector tube.
The aforesaid low pressure condition may be obtained by a fluid injecting device, which may utilize steam or squeous ammonia, the fluid injecting device being mounted at the top of the riser column.
The movable bridge collector tube, for connection to the adjacent oven, comprises an inverted U-shape steel tube which is resistant to corrosion and to a temperature of 1200°C. This bridge collector tube is further provided with an electromagnet for raising the cover of the associated opening in the oven.
The presence of the aforesaid bridge collector tube permits a greater equilibrium and a better distribution of the developed gas pressures during the oven loading to be obtained, and in addition it assures, in any case, the connection between the upper section of the oven and the low pressure duct as far as the said riser column.
The possibility of connecting the adjacent oven to that being loaded, by means of the bridge collector tube permits emission during the loading operations to be greatly reduced. For example, an increase of coal dust in the tar produced is avoided.
In fact, the slow passage of the gases and dust, from the oven being loaded, through the upper part of the adjacent oven, which is generally at the end of distillation, permits the dust to settle. The loading hoppers are made of stainless steel and have a frustoconical cross section, and preferably rest on rubber blocks in order to isolate the apparatus from possible vibrations produced by the vibrators.
Each loading hopper is provided with a loading shutter consisting of a frustoconical element which is able to fit over the opening in the silo containing the coal, the height of which may be adjusted as desired in dependence on the desired volume of coal to be loaded in the hopper. This adaption operation is obtained by varying the vertical position of the lower base of the said frustoconical element.
The loading funnels are provided with couplings operative to permit them to fit the loading apertures perfectly, with a good tolerance margin in order to compensate for possible misalignments of these apertures. The ball valve with which each loading funnel is provided serves to retain the coal within the hopper before it is loaded into the oven and to guarantee gas tightness of the seal against fumes whilst loading is taking place. The closure of this ball valve is controlled by coal level sensors in each hopper.
The improved apparatus of the present invention permits most of the atmospheric pollution problems, which occur during oven loading to be solved, as well as various problems connected to the working environment of the coke oven.
In fact, the possibility of having variable capacity hoppers for performing differential loading, and gradually withdrawing the emitted gases through the columns of two adjacent ovens, connected by the said bridging collector tube, permits the occurrence of excess pressure in the barrel to be eliminated, which excess pressures would deleteriously affect the other ovens of the gang by indirectly increasing the gas leaks through the so-called weak points such as doors, apertures, columns and so on.
The gas emissions are, however, eliminated or at least reduced to the fact that all the loading operations are carried out without there being any need to move the apparatus and the tight closure between the oven and the loading hopper.
Furthermore, the apparatus permits the volumetric distribution of coal in the oven to be improved by differential loading, Moreover, the possibility of being able to clear the dust from the gas and dust mixture during the gas escape, permits the entrainment of coal dust by the gases to be reduced, and accordingly the quality of the tar produced is not deteriorated.
In order better to understand the constructional and the operating characteristics of the improved coke oven gang loading apparatus of the present invention, this will now be described with reference to the figures of the accompanying drawings, which illustrate a preferred exemplary but not limitative embodiment of the present invention, and in which:

Fig. 1 is a schematic view of the coke oven loading apparatus of the invention;
Fig. 2 is a schematic sectional front view of the apparatus illustrated in Fig. 1, taken on the line A-B of Fig. 1; and
Fig. 3 is a schematic side view of the apparatus shown in Fig. 1 and 2.

Referring specifically to the figures of the accompanying drawings, the improved apparatus for loading a gang of coke ovens consists of four movable carriages 1. Each of these latter is formed by a rocker element, connected to a support structure 2 by means of coil springs. Each said carriage 1 is provided with two wheels 3 and 3', of which one wheel is a freely rotatable one and the other is a driving wheel. This latter is driven by a variable speed motor provided with eddy current braking equipment and with a tachometric dynamo for synchronisation of the carriages 1.
The support structure 2 consists of a welded and bolted construction in the form of a portal. At the top of the said support structure 2 there is located a floor carrying the hoppers 4, the operating cab 5 and the housing 6 for the electrical equipment.
The hoppers 4, generally four in number, are preferably made of stainless steel, having frusto- conical cross-section, and each is provided, in the upper part thereof, with a loading shutter 7 for adjusting the amount of coal to obtain a coal charge, variable in weight and distribution, in the loading chamber. Each loading shutter 7 consists of a frusto-conical element of variable height which can be positioned under an outlet 8 from the silo containing the coal, and which allows the useful volume within the hopper to be varied.
The lower portion of each said hopper 4 is communicated with corresponding loading funnel 9 which is vertically movable by hydrodynamic drive means. Each funnel 9 is provided at one end thereof with a coupling sealing ring 10 which permits a perfect fit over the mouth of the loading aperture 11 to be obtained.
Moreover, within each funnel 9 there is provided a closure ball valve 12 for retaining the coal within the hopper before it is loaded into the oven, and for providing a seal against fumes whilst the loading operation is taking place. The closure of this ball valve 12 is controlled by coal level sensors located in each hopper, which operate a suitable hydraulic device.
The loading apparatus of the invention is further provided with four devices 13 for raising the covers of the loading apertures 11, and with four devices 15 for cleaning and degraphitising the loading aperatures 11 before the coal loading operation. The raising of the covers is effected by means of a magnetic plate 14 located at the end of each of the devices 13. Each cleaning device 15 consists of an hydraulic cylinder which drives a suitable cleaning counterweight 15', preferably of the vibrating type.
On the coke discharge side the oven loading apparatus of the invention is provided with a bridging collector tube 16 of inverted U-shape, which permits connection of a suitable aperture 17, formed in the top of an oven, with another suitable aperture 18 formed in the top of the adjacent oven along the distillation path.
In order to raise the covers of the apertures 17 and 18 there is provided an electromagnetic device 19 which also has magnetic plates at the end thereof, like the devices 13.
The bridging collector tube 16 is made of special steel resistant against high temperatures (1200°C) and is positioned onto the associated apertures 17 and 18 by means of an automatic hydraulic drive.
In order to prevent interference between the collector tube 16 and the coal silo tower from occurring during movement of the loading apparatus, the assembly for raising the tube 16, and the cover raising device 19, are displaceable inwardly of the apparatus.
Furthermore, the whole unit is longitudinally movable along a path corresponding to the length of the oven gang in order to permit it to be used with the end ovens of each gang.
During the whole of the loading stage the conveying of the evolved gases is facilitated by a low pressure condition in the upper part of the two ovens connected by means of the said bridging collector tube 1 6. This low pressure is obtained by a fluid injecting device installed at the top of each riser column 20. The oven loading apparatus of the invention is further provided, on the same side as the riser column 20, with a device 21 for automatically cleaning the riser columns, consisting of a member 22 operative to vertically reciprocate a cleaning swab or brush 23.
The present oven loading apparatus is also provided with a drive system, emergency and safety systems, electric and hydraulic systems for automatically performing all the possible desired predetermined sequences of operations, and with a photoelectric cell system for centering the apparatus with respect to the loading aperture.
In order to achieve the optimum loading condition without in practice allowing dust and gas emissions, the present oven loading apparatus provides for varying the weight and volume of the coal in each hopper 4, and an automatic programming of a wide range of different operating sequences for dropping the coal into the loading aperture 11. Accordingly, depending on the inherent characteristics of each mixture, the present apparatus permits automatic loading of four apertures 11 to be performed simultaneously, one at a time, two at a time, or two separately and two together and so on. The cab 5 extends the whole length of the apparatus and is provided with large windows having heat-proof glass, a pressurisa.ion system for preventing the ingress of dust, and an air conditioning system for the operator.
The coke oven loading apparatus of the invention has been described herein above only by the way of non-limitative example, with reference to the figures of the accompanying drawings illustrating an exemplary and non-limitative preferred embodiment of the invention.
Therefore, in the practical construction of the present apparatus, various shape, size and structural changes may be made without departing from the scope of the invention as defined in the attached claims.

Claims

1. Apparatus for loading coke ovens arranged in parallel row gangs and provided with loading apertures (11), the apparatus comprising a plurality of movably mounted hoppers (4), a loading funnel (9) at the outlet end of each hopper (4) having means (10, 12) to ensure a gas-tight seal between the hopper outlet and the loading aperture (11) of a coke oven, and suction means (16) for removing gas and dust evolved during loading of the oven, characterized in that at the inlet end of each hopper (4) there is provided a loading shutter element (7) of frustoconical form and variable height for connecting the hopper inlet to a coal containing silo and controlling the amount of coal delivered to the hopper (4), in that the means ensuring a gas-tight seal comprise a coupling sealing ring (10) and a closure ball valve (12), and in that the suction means comprises a bridge collector tube (16) connecting an opening (17) in the oven to be loaded with a like opening (18) in an adjacent oven which is maintained at low pressure by a fluid injecting device at the top of the riser column (20) thereof.

2. Apparatus according to claim 1 characterized in that the closure ball valve (12) is operated by a coal level detecting probes located in each hopper (4).

3. Apparatus according to claim 1 and 2 characterized in that the magnetic plate (14) for raising the oven cover is arranged in alignment with the loading hoppers (4).

4. Apparatus according to claims 1-3 characterized in that vibrating cleaning devices are arranged in connection to the loading mouths (11) and riser column (20).