GB2202616A

GB2202616A - Cooling the loading installation of a shaft furnace

Info

Publication number: GB2202616A
Application number: GB08806656A
Authority: GB
Inventors: Guy Thillen; Emile Lonardi; Pierre Mailliet; Gilbert Bernard
Original assignee: Paul Wurth SA
Current assignee: Paul Wurth SA
Priority date: 1987-03-24
Filing date: 1988-03-21
Publication date: 1988-09-28
Anticipated expiration: 2008-03-21
Also published as: FR2613052A1; DE3809533A1; LU86818A1; FR2613052B1; CN88101377A; GB8806656D0; IT8819702A0; DE3809533C2; JPS63259005A; JP2832350B2; IT1216032B; CN1012736B; GB2202616B

Description

PROCESS AND APPARATUS FOR COOLING A LOADING INSTALLATION OF A SHAFT

FURNACE.

2 2 0 2 6!U,(' The present invention relates to a process and apparatus for cooling a-loading installation of a shaft furnace, comprising a fixed feed duct arranged verti cally in the centre of the furnace head, a rotary sleeve mounted coaxially round the said feed duct, a fixed outer casing mounted coaxially outside the said sleeve and laterally delimiting with the latter a substantially annular chamber, this chamber being separated, but not isolated from the interior of the furnace by means of a rotary cage integral with the rotary sleeve, a distributing chute mounted pivotally in the rotary cage, a drive means for rotating the sleeve and the cage as a single unit about the vertical axis of the furnace and of the feed duct, an annular feed tank which is fastened to the upper edge of the rotary sleeve and the outer and inner concentric walls of which slide in concentric grooves of a fixed upper plate, through which passes at least one cooling-water intake pipe feeding the annular tank, several cooling coils arranged around the rotary cage and each connected to the said annular tank by means of a pipe, a circular collector fastened to the outer casing, and pipes connecting each of the coils to the collector, so that the water flows between the annular tank and the collector via the said pipes and the coils.

The first'liquid-cooling apparatus of this type used for a loading installation of a shaft furnace is pro- vided in the document EP-Bl-116,142. Despite all the precautions and. arrangements adopted in this known cooling apparatus, it was found that dust and dirt, albeit in small quantities, eventually infiltrates into the cooling liquid. It was found that most of the dirt entered via the upper edges of the feed tank, coming either from the central feed duct or fr.om the annular chamber round the rotary cage. This dirt is deposited greatly reduces the cross-section o not only a reduction in the rate of cooling liquid and consequently an of a deposit, but also a reduction capacity because of the insulating deposits.

in the coils and these. This causes circulation of the increase in the risks in the cooling layer formed by these The object of the present invention is to improve the known liquid-cooling apparatus described above, so as to reduce the penetration of dust and dirt into the cooling circuit.

To achieve this object, the present invention provides a 1 iqui that an d-cooling process characterized essentially in inert gas or purified blast-furnace gas is injected into the annular feed tank at a pressure higher than that prevailing inside the furnace and below the injection pressure of the water into the tank.

This injection of gas achieves a twofold result. In fact, because a pressure higher than that prevailing in the furnace is generated above the level of liquid in the tank, the penetration of dust-laden gases into this tank is prevented or at least reduced. Furthermore, because a cer level of the cooling water, an increase in the head of water is simulated, that is to say the rate of circulation in the coils is increased and this results in more efficient cooling and a reduction in the risks that deposits will form in the coils.

ain pressure is generated above the upper As an auxiliary measure, the penetration of the dustladen gases into the an.nular chamber is reduced by using the collector as a liquid barrier between the furnace and this annular chamber. Moreover, the gases from the furnace which, despite everything, succeed in passing through said liquid barrier are forced to pass through a water curtain which serves to-scrub the gases and precipitate the solid particles.

It is advantageous to provide a settling basin in the cooling circuit, to cause the solid particles in the cooling Liquid to be deposited and so that it is possibLe for the Latter to be reused.

The apparatus provided for carrying out this process is characterized in that the annular feed tank is connected to a compressed-gas pipe via a gas distribution manifold. The rotary cage preferably has a peripheral lip descending to the bottom of the collector and defining with the inner wall of the latter a gas passage labyrinth.

According to an advantageous embodiment, a circular bank of nozzles is provided in the casing above the collector, these nozzles each producing a jet of water in the form of an open fan directed towards the lip of the rotary cage, so as to form a continuous water curtain above the collector.

This collector is preferably connected to the first compartment of a settling basin, which is separated from the second compartment of this same basin by means of a vertical partition extending from the bottom into the upper region of the basin, this second com- partment being connected to the cooling-water top-up supply and to the recycling circuit.

Other particular features and characteristics will emerge from the detailed description of an advantageous embodiment given below by way of illustration, with reference to the accompanying drawings in which:

Figure 1 shows a general diagrammatic view of a cooling apparatus of the type described in the abovementioned document and containing improvements provided as a result of the-present invention; Figure 2 shows a sectional view of the details of the cooling-liquid feed tank; Figure 3 shows a sectional view of the details of the cooling-liquid collector, and Figure 4 shows a view of the curtain of liquid formed above the collector.

Figure 1 shows diagrammatically the drive device of a distributing chute of a loading installation of a shaft furnace, equipped with a liquidcooling apparatus of the type provided in the abovementioned document.

This mechanism essentially comprises two sets of gears 14 and 16 serving respectively for rotating a sleeve 18 about the central axis of the furnace, in order to rotate the distributing chute (not shown in the Figure) about the longitudinal axis of the furnace, and for the angular adjustment of this chute in re lations to this longitudinal axis. The transmission of the movements and the suspension of the movable ele ments are obtained.. in a way known per se, by means of rolling bearings 22 28 (see Figure 2) and will not be described in detail in the context of this application.

An outer casing 24 laterally delimits, with the rotary sleeve 18, an annular chamber 26. This annular chamber is separated from the interior of the furnace by means of a suspension cage 30 for the chute, this cage being integral with the rotary sleeve 18.

As in the known liquid-cooling apparatus, the rotary cage 30 is equipped on the outside with cooling coils 32, to prevent this cage 30 from transmitting the heat to other components, such as, for example, the bearings and gears, either by conduction or by radiation. The various coils 32 are connected, via connecting pipes 38, to an annular feed tank 40 attached to the upper part of the sleeve 18 and consequently rotating together with this about the vertical axis.

As in the known cooling apparatus, the cooling water flows, as a result of gravity, through the coils 32 into a circular collector 60 arranged round the bottom of the rotary cage 30. From this collector 60, the cooling water is recirculated via a resettling basin 80, a pumping assembly 82, a self-cleaning filter 84 and a cooling circuit 86 into pipes 54 feeding the annular tank 40. Reference may be made to the abovementioned document EPBl-0,116,142 for more comprehensive information on the details of the cooling circuit and its mode of operation.

As can be seen from Figure 2, the upper edges of the feed tank 40 travel without contact in concentric circular grooves 46,48 of a fixed upper plate 44 welded to the casing 24. Cooling water is fed to the tank 40 via a circular channel 52 in the plate 44 and into which the feed pipe(s) 54 open(s) (see Figure 1).

As can be seen in Figure 2, the aperture between the upper edges of the tank 40 and the grooves 46,48 has deliberately been designed in the form of a laby- rinth in order to reduce the risks that gas and dust will pass into the tank 40, and to cause a loss of pressure in the sealing gas described below. In spite of these apertures in labyrinth form, it was found that dust coming essentially from the gases rising from inside the furnace via the sleeve 18 still penetrated into the tank 40. According to the present invention, the risks of the penetration of dust into the tank 40 are reduced by injecting an inert gas or Purified blast-furnace gas under prettUtO, fOr GXaMPL@ nitrOg@n., into the latter via one or more pipes 56. This gas is injected at a pressure slightly higher than that prevailing in the blast furnace, to prevent gas from penetrating via the grooves 46 and 48, and at a pressure below the press'ure of the water in the intake pipes 54, so as not to prevent the cooling water from entering the tank 40. This com- pressed gas enters the tank 40 via an annular distribution manifold 58 with a perforated wall.

The present invention also provides measures for reducing the penetration of dust into the annular chamber 26, in order by this route also, to limit the access of dust into the tank 40 and spare the gears and bearings from dust deposits. In fact, there necessarily has to be a circular gap between the rotary sleeve and the fixed casing 24. Now pressure fluctuations inside the furnace generate a pumping effect between the chamber 26 and the interior of the furnace via this gap, thus assisting the passage of small quantities of dust-laden gas into the chamber 26.

To overcome this disadvantage, the collector 60 is designed in the form of a circular tank of rectangular cross-section incorporated in the casing 24. The lower edge of the rotary cage 30 has a vertical peripheral lip 62 which extends over the inner edge of the col- lector 60 to the bottom of the latter, but without being in contact with this collector 60. The passage formed around the inner wall of the collector 60, on the one hand, and the edge of the rotary cage 30 and its Lip 62, on the other hand, is furthermore deliberately ob- structed by a peripheral circular strip 64 of the cage 30 which, during the rotation of this cage 30, travels in a groove 64 made in,the inner wall of the collector 60. The labyrinth defined by the shape of this passage and by the strip 64 and the groove 66 consequently opposes the passage of the gases and dust from inside the furnace into the collector 60. Moreover, it is pos- sible to provide measures for ensuring a minimum level of liquid in the collector 60, so that the lower edge of the lip 62 is within the liquid, thereby forming a liquid barrier between the furnace interior and the chamber 26.

As an additional measure, in an advantageous embodiment there is, above the outer edge of the collector 60, a circular bank of nozzles 68, through which cooling water is injected via pipes 72 branching off from the main circuit (see Figure 1). As shown in Figure 4, each of the nozzles 68. produces a jet of water 70 in the form of a wide fan directed towards the lip 62. The combined effect of all the nozzles 68 thus makes it possible to form a continuous water curtain covering the entire collector 60 and ensuring effective scavenging of the gases which, despite everything, succeed in entering the collector 60 via the labyrinth.

The collector 60 is connected to a settling basin 80 by means of pipes 74 (see Figure 1). This basin 80 is separated into two compartments 88 and 90 by means of a vertical partition 92 extending from the bottom into the upper region. The water coming from the collector 60 is introduced into the compartment 88, where the solid particles can settle on the bottom, whilst the clarified water can enter the second compartment 90 only o ment 9 supply evapor bottom ver the separating partition 92. This compart0 is likewise connected to a feed pipe 94 for ing top-up water to the circuit in place of the ated water. The water is extracted through the of the basin 80 by means of the. assembly of pumps 82 and returned; in a way known per se, to the -8 cooling circuit via the filter 84. The two compartments 88, 90 of the settling basin 80 can be emptied by means of a set of valves 96, in particular in order to remove the solid'deposits from the compartment 88.

It remains to be stressed that the improvements provided as a result of the present invention can easily be adapted to existing installations of the type described in the document EP-Bl-0,116,142.

Claims

CLAI1MS is 1. Process for cooling a loading installation of a shaft

furnace, comprising a fixed feed duct arranged vertically in the centre of the furncace head, a rotary sleeve mounted coaxially round the said duct, an outer casing mounted coaxially outside the said sleeve and laterally delimiting with the latter a substantially annular chamber, this chamber being separated, but not isolated from the interior of the furnace by means of a rotary cage integral with the rotary sleeve, a distributing chute mounted pivotably in the rotary cage, a drive means for rotating the sleeve and the cage as a single unit about the vertical axis and the feed duct, an annular feed tank which is fastened to the upper edge of the rotary sleeve and the two outer and inner concentric walls of which slide in concentric grooves of a fixed upper plate, through which passes at least one cooling-water in-Lake pipe feeding the annular tank, several cooling coils arranged around the cage and each connected to the said annular tank by means of a pipe, a circular collector fastened to the outer casing, and pipes connecting each of the coils to the said collector, so that the water flows between the annular tank and the collector via the said pipes and the coils, wherein an inert gas or purified blastfurnace gas is injected into the annular tank at a pressure higher than that prevailing inside the furnace and below the injection pressure of the water into the tank.
2. Process according to claim 1, wherein the collector is used as a liquid barrier between the furnace and the annular chamber.
3. Process according to claim 2, wherein the gases from the furnace which succeed in passing through the said liquid barrier are forced to pass through a-continuous - water curtain above the collector.
4. Process according to any one of claims 1 to 3, wherein clarification of the cooling water is brought about in a settling basin.
5. Apparatus for carrying out a process according tb any one of claims 1 to 4, wherein the annular feed tank is connected to at least one compressed-gas pipe via gas distribution manifold.
6. Apparatus according to claim 5, wherein the rotary cage has a peripheral lip descending to the bottom of the collector and defining with the inner wall of the latter a gas passage labyrinth.
7. Apparatus according to claim 6, further comprising a circular bank of nozzles provided in the casing above the collector and each producing a jet of water in the form of an open fan directed towards the lip of the rotary cage, as to form a continuous water curtain above the collector.
8. Apparatus according to claim 6, wherein the collector is connected to the first compartment of a settling basin, which is separated from the second compartment of this same basin by means of a vertical partition extending from the bottom of the basin into the upper region of the latter, and wherein the second compartment is connected to a coolingwater top-up supply and to the cooling-water recycling circuit.
9. Process substantially as hereinbefore described with reference to the accompanying drawings.
10. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.

Published 1988 at The Patent Office, State House, 66171 High Holborn, London WC1R 4TP. Farther copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1187.

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