EP1380804A1 - Cooling device for a smelting furnace, smelting furnace with such a cooling device and cooling method for a smelting furnace - Google Patents

Abstract

The cooling device for the furnace (1) includes a bath (2) for the material (3) to be melted within its wall (5) and a cooling element (4), which consists of two tubes, one of which is at least partly inside the other. This forms at least one input line and at least one output line for the coolant. The coolant is pumped through the cooling element.

Description

The invention relates to a cooling device for a Melting furnace according to claim 1, a melting furnace with a such cooling device according to claim 6, a method for Cooling a melting furnace according to claim 12 and a Cooling element according to claim 17.

When operating a melting furnace occur regularly Conditions leading to high thermal, chemical and mechanical stress for the lining used refractory bricks. The thermal and mechanical stress is particularly high in melting furnaces with excessive temperature fluctuations leading changing Composition of the melt, e.g. Slag from the Waste incineration, or those that are not in continuous operation to run. Especially in melting furnaces for melting The brickwork also becomes slag from waste incineration chemically by aggressive gases, e.g. Hydrochloric, Hydrogen fluoride, hydrogen sulfide, contaminated. in the Chemical compounds arising inside the furnace can Attack refractory bricks, reduce their stability and lead to their dissolution. Therefore exist for such ovens strict security requirements that limit the risk of Breakthroughs in the furnace wall as much as possible should reduce.

To an excessive wear and thus reduced Downtimes and the associated economic Various cooling systems are to prevent disadvantages known. For example, it is known the smelting furnace not to be bricked up above the melting zone and with Equip cooling tubes that support the furnace cover. However, this protective measure primarily affects the Vaulted ceiling. The copper cooling tubes used or steel need to be replaced after a period of time be what is also the operating time of the plant negative impaired. For cooling the side wall of the melting furnace in the melting zone, for example Cooling elements from the outside in the masonry parts brought in. The cooling elements are closed Cooling circuit connected and can also be interchangeable his. From DE 36 03 783 is also known to cooling elements connected to a closed cooling circuit from the outside in contact with the furnace wall bring to cool this. After all, it is too known, the furnace wall from the outside with a coolant, e.g. a film of water to wet.

The disadvantage of the known systems that the masonry of cool outside or by means arranged in the masonry, lies in the fact that they are relatively large Cooling capacity or large heat flow can be designed to the area bordering the inside of the furnace the brick lining exposed to the highest temperatures is to cool to the desired temperature. The maximal Cooling power is not provided in the place where it is on yourself is necessary. The cooling elements must therefore absorb relatively large volumes of cooling medium. This In the event of a leak, there is a risk that the inside of the furnace incoming coolant evaporates explosively, which makes the cooling elements and the entire system strong can be damaged.

DE 19 34 486 describes a device for cooling Masonry parts exposed to heat in a melting furnace known the several, directly on the inside of the furnace includes pipes arranged on the lining. The two Tubes divided into chambers are partially with a Cooling liquid, especially water, filled and on her upper end with a condenser and steam generator device connected so that each tube has one represents closed cycle. The circulation of the coolant happens purely by convection. The Pipes are arranged directly adjacent to the furnace wall, so that on the side facing away from the wall the tubes form a layer of solidified melting material. This provides an additional heat shield for the Masonry, but prevents individual pipes in the Damage can be replaced. Furthermore, the Cooling performance from the outside due to the purely passive Circulation of the coolant is difficult to monitor or be adjusted. For example, this is due to interference Blockage or leakage is not immediate recognizable. Temperature changes in the melt cannot be balanced.

From GB-A 2 131 137 is a cooling element for arrangement known on the inner wall of a melting furnace. This consists of a serpentine winding tube, the is cast into a flat copper plate. The Connections for the supply and discharge of the coolant protrude from the copper plate. The flat cooling element comes with several mounting elements on the inside wall of the Oven assembled. The disadvantage of this is that Cooling element not easily in the event of wear can be exchanged.

The invention has for its object the known To further develop cooling devices and cooling elements that avoided the disadvantages of the prior art become. In particular, the cooling elements should be light be producible and interchangeable. Furthermore, one should Melting furnace with such a cooling device and a Methods for cooling a melting furnace can be specified.

The task is solved by a cooling device with the Features of claim 1, a furnace with a such a cooling device with the features of claim 6, a method for cooling a melting furnace with the Features of claim 12 and a cooling element with the Features of claim 17. Advantageous further developments result from the dependent claims, the Description and the drawings.

The cooling device according to the invention for one Melting furnace comprises a plurality of elongated cooling elements to direct a cooling fluid, each at least one supply line and one with fluid dynamics have connected discharge line for the cooling fluid. The The cooling element according to the invention consists of at least two tubular elements partially arranged one inside the other, hereinafter referred to as the inner and outer tubes become. The inner tube serves as a feed or. Derivation and the space between the two tubes as a discharge or supply line for the cooling fluid. "Elongated" means that the length of the cooling element be significantly greater than Diameter is preferably a multiple. In order to can be selectively chilled and a predetermined one Temperature profile can be set. Such a cooling lance can be produced easily and inexpensively, especially if they consist of two at the bottom there are nested hollow cylinders. The Cooling element is easy to assemble or replace because it only led through the furnace wall and there must be attached. The arrangement of two tubes one another has the advantage of a very simple construction an enlarged contact area and good ones Controllability of the coolant flows.

The cooling fluid, which is preferably water, becomes preferably by means of a suitable pump device promoted by the cooling element. By suitable choice of the pressure of the cooling fluid can Cooling capacity to the actual conditions be adjusted inside the oven. This is especially for Smelting furnaces with changing composition of the Melting material, e.g. those for melting slag waste incineration, beneficial. The invention can however also with melting furnaces with constant Loading, e.g. Glass or metal melting furnaces, with Advantage.

The cooling elements are preferably in the interior of the oven At least partially in the vicinity of the lining to be cooled arranged to be immersed, particularly preferred spaced from the lining. Keeping one Distance to the wall has the advantage that the melt solidified between the wall and cooling elements, which means that System becomes sluggish and a kind of protective shield for the wall is formed. If a cooling element fails, the Melt melted in the area, so that a new cooling element can be inserted into this area can.

If the cooling elements are directly adjacent to the wall are arranged, they can be advantageous additionally take on a supporting function of the wall.

The operating parameters of the cooling device are preferably selected so that the melting material is in the range the lining solidifies and thus a thermal one Forms a protective shield for the lining.

In a particularly preferred development of the invention the cooling elements are permeable to the cooling fluid designed. This allows cooling fluid to flow through the wall or Exit the surface of the cooling element into the interior of the oven and by means of evaporative cooling, the cooling effect strengthen. By evaporation even small amounts Cooling liquid manages the cooling elements and thus the Effectively cool the melt in the desired area. in the In contrast, all known cooling systems are like this designed that the release of cooling medium in the Stove interior is avoided at all costs reaction conditions there not by supplying Coolant, often water, change and become an explosive Evaporation of large amounts of coolant to prevent. It has now surprisingly been shown that smaller with the targeted release according to the invention Amounts of cooling fluid in the furnace interior which were feared there are no negative consequences. The conditions in The interior does not remove the amount released changed significantly. A sudden vaporization of large Amounts of coolant are avoided by using the Surface of the cooling element a predetermined permeability has, so that a sudden heat transfer the entire cooling fluid contained in the cooling element is avoided becomes. The amount of coolant dispensed is always one Much less than the returning quantity. Since the Evaporation heat from water is very high, which can lead to Achieving a certain cooling capacity necessary Amount of water to 1/10 to 1/16 of the nominal amount of water of a conventional cooling system with a closed one Cooling circuit can be reduced. It was assumed that the water in a conventional cooling system heated without pressure from approx. 40 ° C to approx. 80 ° C while it warms up to approx. 600 ° C when released into the oven and absorbs a correspondingly larger amount of heat.

Furthermore, the choice of the Flow rate the required amount of cooling fluid per cooling element can be kept very small, so that the Risk of damage remains low even with a leak.

The melting furnace according to the invention is characterized by a longer service life and thus greater economy out. The use of the Cooling device for smelting furnaces for slag from waste incineration. The due to the different slag composition occurring temperature peaks and the chemical pollution of the masonry can be kept low by always operating the cooling device that the masonry with a protective layer of solidified Slag is provided.

The cooling device is preferably modular from individual Built cooling elements that are independent of each other and together with your own or a common one Pump device locally each a cooling circuit can train. The advantages lie in the cost-effective Manufacturing and easy assembly and maintenance or Renovation.

The functionality of the preferably modular individual cooling elements built cooling device can can be easily monitored by the difference between the to- and the derived amount of cooling fluid measured becomes. This makes leaks easy determine. The cooling capacity can, for example, by Setting the amount of per unit time through the cooling elements pumped medium are adjusted, in particular by adjusting the pump pressure.

If one or more of the cooling elements fails, it melts the solidified melting material in the area of the defective cooling element. Due to the modular structure of the cooling device the defective cooling element can be fully received Functionality of the other cooling elements from the cooling circuit uncoupled, pushed into the oven, through Melt with the melted material and discarded by a pushed intact cooling element to be replaced.

The cooling device according to the invention is preferred used as a supplement to known cooling devices, the masonry from the outside or within the masonry cool. In this case, these systems can be smaller be dimensioned. Furthermore, the failure of one of the cooling systems is not yet mandatory in such a case to the fact that the operation of the furnace must be interrupted.

Fig. 1

einen Längsschnitt durch einen Schmelzofen mit einer Kühleinrichtung;

Fig. 1a

einen Längsschnitt durch einen Schmelzofen mit einer Kühleinrichtung und einer abgeschrägten Ofenwandung;

Fig. 2

den Ofen aus Fig. 1 im Querschnitt;

Fig. 3

einen Seitenbereich des Ofens aus Fig. 1 in vergrösserter Darstellung;

Fig. 4

eine Ansicht eines Kühlelements;

Fig. 5

das Kühlelement aus Fig. 4 im Längsschnitt;

Fig. 6

ein weiteres Kühlelement im Längsschnitt.

Examples of the invention are shown in the drawings and described below. It shows purely schematically:

Fig. 1

a longitudinal section through a melting furnace with a cooling device;

Fig. 1a

a longitudinal section through a melting furnace with a cooling device and a chamfered furnace wall;

Fig. 2

the oven of Figure 1 in cross section.

Fig. 3

a side region of the furnace of Figure 1 in an enlarged view.

Fig. 4

a view of a cooling element;

Fig. 5

the cooling element of Figure 4 in longitudinal section.

Fig. 6

another cooling element in longitudinal section.

1 shows a longitudinal section through a melting furnace 1 for melting slag from waste incineration. Fig. 2 shows a cross section of the melting furnace 1, Fig. 3 a enlarged section from FIG. 1. The melting furnace 1 comprises a tub 2 with a bottom 6 and one Side wall 5 for the melting material 3. Under melting material 3 both the still solid 3a, i.e. the solid slag or pyrolysis coke, as well as the already melted good 3b (melt) understood. The solid melt 3a is the Furnace 2 fed through a first shaft 8, where a mountain 3c can form from solids, which over the normal level N of the melt 3b protrudes. The fuel gas or pyrolysis gas is the furnace interior 1 'via nozzles 12, 13th fed. These are in the wall of a second one Shaft 9 arranged to discharge the furnace gases for Afterburner serves. The tub 2 is through the side Side wall 5 made of a heat-resistant material limited. The floor 6 is lowered in places (area 6a) to the liquid metal components of the slag better from the residues floating on the metal to be able to separate.

Figure 1a shows a modification of that shown in Fig. 1 Oven 1. The bottom 6 of the tub 2 is in the area 6b Side wall 5 designed obliquely ascending. So that will the contact surface of the melt 3b with the side wall 5 significantly reduced. The cooling element 4 only dips on his lower end 4a into the melt 3b.

As shown in Fig. 3, the side wall 5 consists of two layers of refractory bricks 5a, 5b and closes with an outer skin 5c, which extends upwards in the direction of first shaft 8 continues and forms its wall. The outer skin 5c is used to cool the furnace in itself known way wetted with water 7. The refractory bricks 5a, 5b have cutouts 10 which are known per se Way to serve a cooling medium. In addition to The side wall becomes the known cooling measures by the cooling device according to the invention cooled.

The cooling device according to the invention comprises a plurality of cooling elements 4, which are inside the furnace 1 are arranged. The rod-shaped or lance-shaped cooling elements 4 are from above through suitable openings 11 in the Oven wall inserted into the interior of oven 1. she run in the vertical direction and have a distance d from the side wall 5 of preferably 1 to 10 cm, particularly preferably 2-3 cm. The cooling elements 4 protrude their front or lower end 4a in the melt 3b into it. The operating conditions of the cooling device, in particular the distance D between the cooling elements 4 and the distance d to the side wall 5 and the Cooling performance of a single cooling element 4 is preferred chosen so that the melt 3b in the range between the cooling elements 4 and the side wall 5 solidify. The solidified slag forms a protective shield for the Side wall 5. If a cooling element 4 fails, it melts the solidified slag locally, whereby the wall 5 as However, the whole thing is not charged. The defective cooling element 4 can then be removed from its working position and through a new one will be replaced. The defective cooling element 4 will pulled from the opening 1 from above, for example. However, disposal is particularly preferably carried out by the cooling element 4 is pushed into the furnace 1 where it melts with the melting material 3.

The cooling elements 4, which are in Fig. 4 in supervision and in 5 and 6 in two different embodiments in Section shown in more detail consist of two at least in the intended for arrangement within the oven lower region 4a concentric to the longitudinal axis A tubes 14, 15 arranged one inside the other. The inner tube 14 is intended for arrangement outside the furnace 1 upper area 4b out of the outer tube 15, see above that both tubes don't connect one here coolant circuit shown are accessible.

Both tubes are bent in the upper region 4b. At her Free ends 14b, 15b are preferably connections to Connection of the cooling circuit available (not here shown). Because of the small diameter, this can Cooling element 4 easily through a small opening in the Furnace wall are introduced into the melting furnace. On such cooling element 4, which is preferably made of steel, is easy and inexpensive to manufacture and therefore as Wear part suitable.

The inner and outer tubes 14, 15 each have the Shape of a hollow cylinder with a circular Cross-section, but in principle there are also others Cross-sectional shapes in question. The outside diameter of the inner tube 14 is smaller than the inner diameter of the outer tube so that between the tubes 14, 15 as a Derivation 20 is formed for the coolant-serving space is. In the present case, the inner tube 14 serves as a feed line 19 for the coolant, especially water. Supply and discharge 19, 20 are fluid dynamically connected to one another by the lower ends 14a, 15a of both tubes 14, 15 through a common plug 17 are closed, the inner Tube 14 in the area of its lower end 14a, however Has openings 18 to the room 20. In the present case, this towers over lower end 15a of outer tube 15, lower end 14a the inner tube 14 approximately in the direction of the axis A. measured length of the plug. The operating conditions, in particular the flow and type of coolant preferably set so that the coolant in the Feed line 19 is liquid and in the discharge line 20 evaporates so that a vapor film forms.

On the outer tube 15, a sleeve 16 is placed, the itself from the lower end of the cooling element 4 to its extends upper area 4b. The not absolutely necessary Sleeve 16 has various functions: In the case of FIG. 5 illustrated first embodiment, it serves as Protective sleeve for the pipe system 14, 15 to one to prevent excessive wear.

Fig. 6 shows a second embodiment of an inventive Cooling element 4. The outer tube 15 is in the lower area 4a designed to be permeable to the coolant, by the tube wall having a plurality of radially extending Has channels 21. The sleeve 16 is also permeable, preferably it consists of a porous Sintered material. The coolant passes through the channels 21 from the discharge line 20 and passes through the porous Sintered material of the sleeve 16 outwards into the furnace interior. The effect can be achieved by the capillary action of the channels 21 be reinforced. By evaporating the coolant from the The surface of the sleeve 16 becomes the cooling element 4 and thus the melting material is cooled. The perspiration according to the invention or evaporative cooling has the advantage that the Dispensing small amounts of cooling medium to an effective one Temperature reduction leads. The small amount of cooling medium affects the reaction conditions inside the furnace Not. Furthermore, the porous sleeve prevents 16 the risk of explosive evaporation is greater Amounts of coolant.

The outer tube 15 may also be a plurality of Segment rings be composed, with the gaps between the individual segments as channels for the Coolant outlet serve (not shown). are the openings in the outer tube 15 can be fine enough also be dispensed with the sleeve 16.

An example of the operating conditions in a system according to the invention is described below: The cooling elements 4 are located directly on the wall and are arranged at a distance D = 25 cm from one another. The inner and outer tubes 14, 15 have a diameter of 21.3 mm and 42.4 mm. The length of the cooling element within the furnace is preferably 30 to 60 cm. Water is used as the coolant. The pressure of the pump device is selected so that the incoming coolant flow is approximately 1000 l / h. Of this, approximately 20 l / h is preferably released to the environment through the permeable surface of the cooling element 4. The channels 21 preferably have a diameter of 2 mm and a total area of 140 mm ² , the porosity of the sintered material is approximately 10%. The coolant heats up only insignificantly when passing through the cooling element, since the wall temperature is kept approximately constant by the water evaporating to the outside.

Claims (21)

Cooling device for a melting furnace (1), which has a trough (2) arranged in the furnace interior (1 ') for receiving the melting material (3, 3a, 3b, 3c) and a wall (5) at least partially delimiting it laterally, comprising a plurality of elongated cooling elements (4) for guiding a cooling fluid, each of which has at least one feed line (19) and a discharge line (20) for the cooling fluid connected to it in a fluid dynamic manner and which are arranged in the interior of the furnace (1 '), characterized in that the cooling elements ( 4) comprise at least one inner tubular element (14) and one outer tubular element (15), the inner tubular element (14) being arranged at least partially in the outer tubular element (15) such that at least one feed line (19) and at least one a drain (20) for the cooling fluid is formed. Cooling device according to claim 1, characterized in that the cooling elements (4) are arranged in the interior of the furnace in spatial proximity to the wall (5), but spaced therefrom. Cooling device according to claim 1 or 2, characterized in that the cooling fluid is forcibly conveyed through the cooling elements (4). Cooling device according to one of the preceding claims, characterized in that the cooling element (4) is designed to be permeable to the cooling fluid, so that cooling fluid can emerge from the cooling element into the furnace interior (1 '). Cooling device according to claim 4, characterized in that the outer tubular element (15) consists at least partially of a porous material and / or has channels (21) and / or is constructed from individual segments between which the cooling fluid can escape. Melting furnace (1), the one arranged inside the furnace Trough (2) for receiving the melting material (3, 3a, 3b, 3c) and one of these at least partially to the side delimiting wall (5), with a Cooling device according to one of the preceding Expectations. Melting furnace according to claim 6, characterized by a pump device for the positive delivery of the cooling fluid. Melting furnace according to claim 6 or 7, characterized in that the cooling elements (4) in the furnace interior (1 ') are arranged in spatial proximity to the wall (5), but spaced therefrom. Melting furnace according to claim 6, 7 or 8, characterized in that the at least one cooling element (4) is at least partially immersed in the melting material (3, 3a, 3b, 3c). Melting furnace according to one of claims 6 to 9, characterized in that the cooling elements (4) are arranged at a distance d of 1 to 10 cm, preferably 2-3 cm, from the wall (5) of the melting furnace (1). Melting furnace according to one of claims 6 to 10, characterized in that the cooling elements (4) in the furnace interior (1 ') are arranged to run in the vertical direction and the furnace wall above the trough (2) has openings (11) through which the cooling element ( 4) are inserted inside the oven. Process for cooling a melting furnace with a Cooling device according to one of claims 1 to 6, wherein a plurality of cooling elements (4) in Furnace interior (1 ') in close proximity to the wall (5) is arranged, at least partially in that Molten material (3, 3a, 3b, 3c) immersed and from one Cooling fluid is flowed through, the cooling capacity the cooling device is chosen such that the Wall (5) does not have a predetermined temperature exceeds. A method according to claim 12, characterized in that the material to be melted (3, 3a, 3b, 3c) is in the molten state and the cooling capacity of the cooling device is selected such that the melt solidifies in the region of the wall (5). Method according to one of claims 12 or 13, characterized in that a cooling element (4) is released from its holder in the wall when worn, so that it falls into the furnace interior, and a new cooling element (4) is arranged in the released position. Method according to one of claims 12 to 14, characterized in that the difference between the amount of cooling fluid supplied to and derived from a cooling element is measured and evaluated in order to determine the functionality or wear of the cooling element (4). Method according to one of claims 12 to 15, characterized in that cooling elements are used which are at least partially permeable to the cooling fluid, and the pressure of the cooling fluid is adjusted such that a predetermined amount of cooling fluid always exits the cooling element. Cooling element (4) for guiding a cooling fluid for a cooling device for a melting furnace (1), the cooling element being elongated and having at least one feed line (19) and a discharge line (20) for the cooling fluid that is connected to it in a fluid dynamic manner, characterized in that the cooling element (4) comprises at least one inner tubular element (14) and one outer tubular element (15), the inner tubular element (14) being arranged in the outer tubular element (15) such that at least one feed line (19) and at least one Derivation (20) for the cooling fluid is formed. Cooling element (4) according to claim 17, characterized in that the inner and the outer tubular element (14, 15) each have the shape of a hollow cylinder with a circular cross section, the outer diameter of the inner tubular element (14) smaller than the inner diameter of the outer tubular element (15). Cooling element (4) according to claim 17 or 18, characterized in that the outer tubular element (15) is permeable to the coolant, preferably in that it has radially outwardly extending channels (21). Cooling element (4) according to one of claims 17-19, characterized by a sleeve (16) which is placed on the outer tubular element (15). and which is preferably permeable to the coolant. Use of an elongated cooling element after a of claims 17-20 in a cooling device one of claims 1 to 5.

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