Method for processing heated material

Abstract

The invention relates to a method for processing heated material (1), wherein the material is guided along a conveying path and is covered and protected against heat loss in the region of the conveying path by at least one reflector element (2), wherein the reflector element (2) is cooled by means of a liquid. According to the invention, in order to guarantee efficient cooling of the reflector without costly measures, the liquid is glycol or comprises glycol or the liquid is alcohol or comprises alcohol or the liquid is thermal oil.

Claims

1. A method for processing hot metal slabs, sheets and strips and similar material (1), wherein the material is guided along a conveying path and is covered and protected against heat loss in the region of the conveying path by at least one reflector element (2), wherein the reflector element (2) is cooled by means of a liquid, characterized in that the reflector element includes a reflector material having a reflectivity of greater than 70%, that the liquid is glycol or comprises glycol or in that the liquid is alcohol or comprises alcohol, or in that the liquid is thermal oil, and that during cooling, the liquid is heated only to a maximum temperature at which it still will not produce vapor pressure, that the liquid is conducted within a closed circuit through the reflector element (2), thereby passing one heat exchanger (3), and that the liquid is held at a predefined temperature by controlling a liquid flow rate based on an actual temperature of the reflector element as the liquid passes through the closed circuit, so that the liquid is kept from evaporation, wherein a volumetric flow rate is used as a control variable.

2. The method according to claim 1, characterized in that the liquid is a mixture of glycol and water.

3. The method according to claim 1, characterized in that the liquid is conducted in the closed circuit through a heat accumulator element.

4. The method according to claim 1, characterized in that the temperature of the liquid is controlled in a range of greater than 80 C. and less than 400 C.

5. The method according to claim 4, characterized in that the temperature of the liquid is controlled such that the liquid will not evaporate.

6. The method according to claim 1, characterized in that the heat drawn from the liquid by the heat exchanger (3) is supplied to a secondary process.

7. The method according to claim 1, characterized in that the at least one reflector element (2) is subjected to a cleaning process after a period of use has elapsed.

8. The method according to claim 7, characterized in that the cleaning process comprises a blowing-off of the reflector surface (4) with a gas, in particular air.

9. The method according to claim 7, characterized in that mechanical means, in particular a cleaning brush, are used for cleaning the reflector surface (4).

10. The method according to claim 7, characterized in that liquid and/or chemical cleaning agents, in particular ethanol or nitric acid, or a mixture of cleaning agents and water are used for cleaning the reflector surface (4).

11. The method according to claim 1, characterized in that a material with a thermal radiation range having a wave length between 0.5 and 10 m is used as the reflector material.

Description

(1) Embodiment examples of the invention are represented in the set of drawings. The drawings show:

(2) FIG. 1 a schematic side view of a portion of a conveyor element for hot material to be rolled, with reflector elements disposed above and below the material for the purpose of radiating heat back onto the material,

(3) FIG. 2 a schematic plan view of the conveyor element according to FIG. 1,

(4) FIG. 3 a schematic view of a reflector element, as viewed in the conveying direction of the material,

(5) FIG. 4a to

(6) FIG. 4f schematically different embodiments of reflector elements, as viewed in cross-section through the heat exchanger, in the conveying direction of the material,

(7) FIG. 5 a reflector element together with the cooling device, as viewed in the conveying direction of the material, and

(8) FIG. 6 the reflector element according to FIG. 5, from a side view.

(9) FIG. 1 shows hot material 1 in the form of a slab, being conveyed in conveying direction F. A roller conveyor 5 is provided for this purpose. Both above and below slab 1, that is to say between two rollers of roller conveyor 5, reflector elements 2 are provided for reflecting back the heat from hot slab 1. Reflector elements 2 are embodied accordingly as reflective heat-insulating hoods, which are also connected to a heat exchanger 3. Heat that is not reflected directly back onto slab 1 by reflector surface 4 of reflector elements 2 is cooled by means of a liquid, which is conducted in ring line 6. The liquid in the embodiment example is glycol or a mixture of glycol and water. The liquid is conveyed through a ring line 6 by means of a motorized circulating pump 7. It is also possible for a heat accumulator (not shown) to be provided within ring line 6, for keeping the cooling liquid at the desired temperature level.

(10) The majority of the heat radiating from slab 1 is therefore reflected back by the specular reflector surface 4 of reflector elements 2, thereby reducing heat loss from the slab. The portion of the heat that is absorbed by the reflector element is diverted by the illustrated closed circuit cooling system, and is thus released to the environment by means of heat exchanger 3. Reflector element 2 is thereby protected against destruction or oxidation.

(11) The fluid is conducted along the side of reflector surface 4 that faces away from slab 1, in order to absorb heat and cool reflector element 2.

(12) Reflector surface 4 of reflector elements 2 can also be embodied as curved somewhat in the longitudinal or the transverse direction, in order to increase mechanical rigidity.

(13) Scale falls onto reflector elements 2, which are arranged below slab 1. The scale particles are cleaned off periodically by blowing them away using an air flow, a process which is facilitated by the inclined mirror surfaces. It is also possible for a thin metal membrane 8 (configured as a wear part) to be attached as a protective measure in front of the mirror; this membrane is shown on the two lower right reflector elements 2. Alternatively, reflective insulation involving mirrors on the upper side can be combined with a conventional type of absorptive insulation (involving a membrane sheet and/or ceramic insulating fibers) on the lower side between the rollers.

(14) The structural configuration of the mirror segments of the reflective heat-insulating hoods 2 is shown FIG. 2 and FIG. 3. A coolant stream 13 flows through segments 9, 10, 11 and 12. The coolant can be settled in a settling section 14.

(15) The mirror of reflector element 2 is held by a mirror support 15. In this case, the flow passes through the reflector elements during the change from the drive side (AS) to the operating side (BS) and from BS to AS.

(16) Various embodiments of reflector elements, in which one side acts as a mirror, are shown in FIGS. 4a to 4f.

(17) FIG. 4a shows a wide rectangular channel, with reflector surface 4 situated on the underside thereof.

(18) FIG. 4b shows a rectangular tube/connector/rectangular tube configuration. The cooling channels are identified as 16.

(19) FIG. 4c shows a plurality of narrow rectangular channels.

(20) FIG. 4d shows a rectangular channel with ribs on the hot side (mirror side).

(21) FIG. 4e shows a pipe/connector/pipe configuration.

(22) FIG. 4f shows a plate heat exchanger with a corrugated rear wall.

(23) FIG. 5 and FIG. 6 illustrate an alternative reflective heat-insulating hood cooling (mirror cooling). Here, the rear side of the reflector is impinged by a coolant jet. The cooling device can be a spray cooling system, a laminar cooling system, a water pool cooling system or a similar apparatus.

(24) In this case, the coolant is sprayed, for example, from a coolant distribution pipe onto the rear surface of the reflector, and on the reflector runs toward the side, thereby cooling the mirror.

(25) To prevent fluid or steam from wetting the mirror surface or from cooling slab 1 or roller conveyor 5, the coolant is captured, collected and selectively diverted. The reflector (mirror) can be pivoted or moved out of the production line in the same manner as the cooling device.

(26) Optionally, this mirror cooling device may also be used, as needed, as a product cooling system (for example as a roughed strip cooler). In this case, the mirror can also be moved on its own out of the transport line, and the cooling medium (in that case, preferably pure water) can cool the roughed strip, for example.

LIST OF REFERENCE NUMERALS

(27) 1 hot material 2 reflector element 3 heat exchanger 4 reflector surface 5 roller conveyor 6 ring line 7 circulating pump 8 metal membrane 9 segment 10 segment 11 segment 12 segment 13 coolant flow 14 coolant settling section 15 mirror support 16 coolant channel F conveying direction