WO2024013216A1 - Method for heating, drying and/or sintering a metallurgical vessel and arrangement thereof - Google Patents

Abstract

The invention relates to a method for heating, drying and/or sintering a metallurgical vessel (1), which is provided with a fireproof lining (2) in its interior. To enable the heating, drying and/or sintering of a vessel in the most ecological way possible without the use of gas, and yet as efficiently as possible, the invention provides that a carrier element (3) is inserted into the interior of the vessel (1), which is provided on its outer circumference with a number of electrical and vacuum-compatible heating elements (4), and that the electrical heating elements (4) are supplied with electrical energy under vacuum for a predetermined time for heating, drying and/or sintering.

Description

Method for heating, drying and/or sintering a metallurgical vessel and arrangement therefor

The invention relates to a method for heating, drying and/or sintering a metallurgical vessel which is provided with a fireproof lining inside. The invention further relates to an arrangement with a metallurgical vessel, which is provided inside with a fireproof lining, and a device for heating, drying and/or sintering the metallurgical vessel under vacuum.

When producing a metallic melt in a corresponding furnace until it is poured and the subsequent secondary metallurgical treatment of the melt, if necessary, there is a need to design the metallurgical vessel so that it can be heated. This ensures compensation for temperature losses that occur through post-treatment of the melt (e.g. in the form of an additional alloy). Such heating is also necessary in order to reduce the necessary tapping temperature of the melting furnace or to be able to set the casting temperature precisely during the process.

For this purpose, it is known to use gas burners for drying and sintering the linings and wear linings of metallurgical vessels in the atmosphere, in particular using natural gas or coke oven gas or blast furnace gas as fuel gas. It is used in the delivery area, in the workshop or in the production plant at the corresponding system.

Such a solution is disclosed in WO 2007/131721 A1. Here, a reflective cap is placed on the vessel, which is fitted with pore burners to heat the inside of the vessel. The Pore burners can also be arranged on a rod-shaped structure that is inserted into the interior of the vessel.

Also known is the vacuum drying and sintering of refractory materials using radiation from heating rods made of silicon carbide. For this purpose, DE 36 37 065 A1 provides that a transversely arranged graphite rod is positioned above the vessel and is supplied with electrical energy. A radiation shield arranged above the graphite rod reflects the resulting heat into the interior of the vessel. US 4,090,054 A also provides a graphite rod which is heated by applying electrical energy, the rod being inserted into the interior of the vessel.

There are various disadvantages when using gas burners as a heating element: First of all, there are undesirable water emissions that arise from the burning of natural gas or coke oven gas or blast furnace gas, which are then absorbed by the refractory mass and later diffuse into the melt. This causes the quality level to deteriorate. The water also runs the risk of the refractory material cracking and wearing out more quickly. Furthermore, there are undesirable CO2 emissions during the drying and preheating of containers, which pollute the atmosphere and the environment. There is also the risk of so-called “hot spots” forming, which lead to cracks in the refractory material and, as a result, to increased wear. Ultimately, open flames pose an increased risk of fire and cannot be operated unattended or unobserved.

The use of inductive heaters or induction coils in containers is sometimes not applicable for drying and heating due to the formation of condensation. Furthermore, application may be excluded due to certain materials, for example austenitic steel. Furthermore, such heaters require an anti-magnetic container Reduction of losses, which results in high manufacturing and material costs when producing the containers.

The invention is based on the task of developing a method of the type mentioned at the outset and a corresponding arrangement in such a way that the disadvantages mentioned are avoided. Accordingly, the heating, drying and/or sintering of a metallurgical vessel should be able to be carried out in the most ecological way possible without the use of gas. Electricity should be used in such a way that heating, drying and sintering can take place under vacuum as efficiently as possible.

The solution to this problem by the invention is characterized in that a carrier element is inserted into the interior of the vessel, which is provided on its outer circumference with a number of electrical heating elements, and that the electrical heating elements are used for heating, drying and /or sintering can be supplied with electrical energy.

Preferably, a negative pressure is generated at least temporarily inside the vessel during heating, drying and/or sintering.

The temperature can be measured at a defined location on the fireproof lining, with the electrical heating elements being operated by a control device in such a way that the temperature at the defined location on the fireproof lining follows a predetermined time course. The temperature can be measured at the defined location of the refractory lining using a temperature sensor, in particular using a thermocouple, using a pyrometer or using an infrared measuring device.

The electrical heating elements preferably heat the temperature of the refractory lining to a value between 200 °C and 1,600 °C. The proposed arrangement with a metallurgical vessel and a device for heating, drying and/or sintering the metallurgical vessel is characterized according to the invention in that the device has a carrier element which is provided on its outer circumference with a number of electrical heating elements.

The carrier element is preferably arranged on a lifting and/or pivoting mechanism. This means that it can be easily inserted or lifted into the interior of the vessel together with the heating elements.

According to a preferred embodiment, the carrier element has a substantially cylindrical outer circumference which carries the electrical heating elements; the lower end region can also be provided with electrical heating elements.

The electrical heating elements are preferably designed as electric resistance radiation heaters. They can be designed based on metallic heating conductors.

A plurality of individual electrical heating elements is preferably provided, although only one of these heating elements can also be present.

In particular, the proposed solution makes it possible to dispense with the use of gas for heating, drying or sintering a metallurgical vessel. Rather, this is done using electrical energy, which can preferably be produced economically as “green electricity”.

The invention is preferably used in metallurgical vessels that are lined with refractory material and are intended for melting and storing metallic melts (for ferrous or non-ferrous alloys). The electrical heating elements used are preferably designed as resistance radiant heaters. In particular, they can have metallic heating conductors.

The permanent lining or the wear lining of the fireproof lining (lining) of the metallurgical vessel is preferably dried or sintered. This can be done in delivery or in the preparation workshop.

It is also possible to preheat the metallurgical vessel immediately before melting, casting or spraying. This can then be done at the appropriate processing facility.

According to the present invention, electrical resistance radiation heaters are used for the task of drying and sintering brick linings and linings as well as preheating containers before use in the melting and casting operation with liquid hot melts, preferably under vacuum.

Furthermore, electrical resistance radiation heaters are used for the task of removing bound water from brick linings, permanent and temporary linings as well as the preheating of containers before use in the casting operation with liquid hot melts, preferably under vacuum.

Finally, the “cooking” of the melt and the resulting adhesion to refractory materials caused by metal splashes in the melting furnaces can be prevented according to the invention (due to a lack of water, there is no dissociation of hydrogen and oxygen at temperatures above 1,000 ° C). The elements of the resistance radiant heating are preferably attached in a form-fitting manner to the lateral surface of a prefabricated support element and connected to an electrical supply source so that the heating can be heated to the required target temperature (up to 1,600 °C).

This advantageously results in a reduction of carbon dioxide through the possible use of climate-neutrally generated electrical energy for drying, preheating and sintering of the metallurgical vessel.

Undesirable water emissions can be avoided, which otherwise arise from the burning of natural gas or coke oven gas or blast furnace gas and which are then absorbed by the refractory mass and later diffuse disadvantageously into the melt.

Furthermore, “hot spots” are prevented by the focal spot, which lead to cracks in the refractory material and subsequently to increased wear.

Finally, “cooking” of the melt and the resulting adhesion to the refractory material caused by metal splashes in the melting furnaces is prevented because, due to a lack of water, dissociation of hydrogen and oxygen cannot take place at temperatures above 1,000 °C.

A single electrical heating system can be provided for all of the tasks mentioned (drying, preheating, heating and removing water) from containers, especially under vacuum.

An exemplary embodiment of the invention is shown in the drawing. The only figure shows schematically the side view of a metallurgical vessel into which a device for heating, drying and/or sintering the interior of the vessel is inserted. The figure initially shows a schematic sketch of a metallurgical vessel 1, which is provided with a fireproof lining 2 on the inside. In the sense of the above explanations, it is useful or necessary for the purposes described there that the interior of the vessel 1 is heated, which results in heating or drying of the vessel or a sintering process. For this purpose, a device 5 for heating, drying and/or sintering is provided, which the figure shows in the state in which the device 5 has been moved into the vessel 1 in order to fulfill the stated purpose.

The device 5 comprises a support element 3, which has a substantially cylindrical shape. Electric heating elements 4 are arranged on the outer circumference of the carrier element 3. These can be supplied with electrical energy via a transformer 10, as indicated in the figure.

To move the carrier element 3 together with heating elements 4 into the interior of the vessel 1, a lifting and/or pivoting mechanism 6 is present, to which the carrier element 3 is attached.

If - as shown in the figure - the carrier element 3 is placed inside the vessel 1, a vacuum lid 6 is placed on the vessel 1. The interior of the vessel is evacuated using a vacuum pump 8. Also shown is a water container 9 in which water can be collected which is removed from the interior of the vessel 1 by the evacuation.

The proposed arrangement is used very advantageously in particular in the following three applications (operational or use situations of the metallurgical vessel):

First of all, the moisture is removed with simultaneous drying and sintering of the permanent refractory lining of the vessel after the brick lining has been re-lined under vacuum. For this purpose, the electrical resistance radiant heating is operated via appropriate vacuum-compatible control devices, power circuits and converters. The drying of the brick lining is then carried out using appropriate control specifications, which are specified in accordance with a required time-temperature curve for the electrical resistance radiant heating. Optionally, built-in temperature sensors (preferably thermocouples) that record the actual temperature of the container lining can be provided, thus forming a closed temperature control loop.

Furthermore, the drying and sintering of a wear lining (also to remove moisture) is provided, which is additionally applied over the permanent lining or the brick lining. At the same time, the electrical resistance radiant heating is operated via appropriate and vacuum-compatible control devices, power circuits and converters. The drying of the wear layer (via the heating of the brick lining carried out by the electrical resistance radiant heating) then takes place via appropriate control specifications for the electrical resistance radiant heating, which correspond to the required time-temperature curve. Here too, optional built-in temperature sensors (in particular thermocouples) can be provided, which record the actual temperature of the container lining and thus form a closed temperature control loop (indirect detection of the temperature of the wear lining).

Finally, the proposed method can be used for preheating and sintering the crucible of furnaces for vacuum induction metallurgy (VIM furnaces) or for the lining and the wear lining before the melting and casting operation. For this purpose, the electrical resistance radiant heating is operated via vacuum-compatible control devices, power circuits and converters. The preheating and sintering of the VIM crucible is then carried out using appropriate control specifications (these correspond again a required time and temperature curve) to the integrated electrical resistance radiant heating. Optionally, built-in temperature sensors can also be provided here (preferably thermocouples, pyrometers or infrared measurements), which record the actual temperature of the lining of the container, the wear lining or a surface temperature of the same (ie indirect detection of the temperature of the wear lining), which in turn forms a closed temperature control loop becomes.

A vacuum-compatible regulation or control of the drying and sintering of the lining of a container can therefore be carried out via at least one electrical heating element of an electrical resistance radiant heater placed in the container. Furthermore, the regulation or control of the drying and sintering of the wear lining of a container is possible via at least one electrical heating element of an electrical resistance radiation heater placed in the container. Finally, the regulation or control of the preheating and sintering of a container is possible via at least one electrical heating element of an electrical resistance radiation heater placed in the container.

For this purpose, at least one element of an electrical resistance radiant heater is placed in the container for preheating and sintering the fireproof lining of a container. Preferably, a control device is provided for adjusting the temperature of the melt in a container via electrical resistance radiation heating, in particular under vacuum. Finally, a regulating device or control device can also be provided for drying, preheating and sintering of the container via electrical resistance radiation heating, in particular under vacuum. List of reference symbols: 1 metallurgical vessel

2 fireproof lining

3 support element

4 electric heating element

5 Device for heating, drying and/or sintering 6 Lifting and/or pivoting mechanism

7 vacuum lids

8 vacuum pump

9 water containers

10 transformer

Claims

Patent claims: 1. A method for heating, drying and/or sintering a metallurgical vessel (1) under vacuum, which is provided in its interior with a fireproof lining (2), characterized in that a carrier element (3) is inserted into the interior of the vessel (1). is retracted, which is provided on its outer circumference with a number of electrical heating elements (4), and that the electrical heating elements (4) are supplied with electrical energy under vacuum for a predetermined time for heating, drying and / or sintering. 2. The method according to claim 1, characterized in that the temperature is measured at a defined location on the fireproof lining (2), the electrical heating elements (4) being operated by a control device in such a way that the temperature at the defined location on the fireproof lining (2) follows a predetermined time course under vacuum. 3. The method according to claim 2, characterized in that the temperature at the defined location of the fireproof lining (2) is measured under vacuum by means of a temperature sensor, in particular by means of a thermocouple, by means of a pyrometer or by means of an infrared measuring device. Method according to one of claims 1 to 3, characterized in that the electrical heating elements (4) heat the temperature of the fireproof lining (2) to a value between 200° C and 1,600° C. Arrangement with a metallurgical vessel (1), which is provided inside with a fireproof lining (2), and a device (5) for heating, drying and / or sintering the metallurgical vessel (1), in particular for carrying out the method according to one of claims 1 to 5, characterized in that the device (5) has a support element (4) which is provided on its outer circumference with a number of vacuum-compatible electrical heating elements (4). Arrangement according to claim 5, characterized in that Support element (3) is arranged on a lifting and / or pivoting mechanism (6). Arrangement according to claim 5 or 6, characterized in that the carrier element (3) has a substantially cylindrical outer circumference which carries the electrical heating elements (4). Arrangement according to claim 7, characterized in that the lower end region is provided with electrical and vacuum-compatible heating elements (4). Arrangement according to one of claims 5 to 8, characterized in that the electrical heating elements (4) are designed as electrical resistance radiation heaters, in particular based on metallic and vacuum-compatible heating conductors.