COOLING SYSTEM FOR ROTARY FURNACES

Abstract

The invention relates to a cooling system (3) for rotary furnaces (1), and also to a method for operating such a cooling system (3). The cooling system (3) comprises for this purpose an arrangement of one or more cooling modules (31, 31, 31), which are arranged in the portion (21) to be cooled of the furnace shell (2), at least along the axis of rotation (R) of the furnace shell (2), wherein each cooling module (31) comprises an activatable switching valve (311) and a fan nozzle (312) for issuing a pulsed fan-shaped cooling liquid jet (4) and, when there are a number of cooling modules, the neighbouring cooling modules (31, 31, 31) are arranged in relation to one another at a distance (A1) parallel to the axis of rotation (R) of the furnace shell (2). Each cooling module (31, 31, 31) comprises at least one first heat sensor (313), connected to a cooling system control (32), for measuring a first local temperature (T1) of the furnace shell (2) ahead of the area of impingement (41) as seen in the direction of rotation (DR) of the furnace shell (2).

Claims

1. A cooling system for rotary furnaces for cooling at least one section of a furnace shell, comprising an arrangement of one or more cooling modules for applying (A) cooling fluid from the outside onto the furnace shell in an impact area of the cooling fluid on the furnace shell, whereby the cooling modules for the section of the furnace shell that is to be cooled are arranged at a distance from the furnace shell, at least along the axis of rotation (R) of the furnace shell, each cooling module having an actuatable on-off valve and a fan nozzle that emits a pulsed fan-shaped cooling fluid jet and, if there are several cooling modules, the adjacent cooling modules are arranged at a distance (A1) relative to each other and parallel to the axis of rotation (R) of the furnace shell in such a way that the impact areas contiguously cool the furnace shell along its axis of rotation (R), at least in the section that is to be cooled, and whereby each cooling module comprises at least a first heat sensor which is connected to a cooling system control unit and which serves to measure a first local temperature (T1) of the furnace shell at a place that is in front of the impact area of the cooling fluid as seen in the direction of rotation (DR) of the furnace shell and which it serves to transmit (U1) the first local temperature (T1) to the cooling system control unit, and the cooling system control unit is configured to actuate the on-off valve of each of the cooling modules in accordance with a difference (DT1) between the appertaining first local temperature (T1) and a setpoint temperature (ST) in such a way thatby setting (E) the pulse length and/or pulse frequency of the cooling fluid jet after one rotation (2Un+1) of the furnace shellthe place (S1) of the furnace shell where the first local temperature (T1) was measured one rotation (2Un) before then has a first local temperature (T1) that is closer to the setpoint temperature (ST) than at the time of the preceding measurement, insofar as cooling fluid was applied onto the appertaining impact area during that particular rotation, whereby, however, the difference (DT1-U) between the first local temperatures (T1, T1) of these two measurements is less than 30K, preferably less than 15K.

2. The cooling system according to claim 1, characterized in that the cooling system control unit is connected to and equipped with the on-off valves of various cooling modules in such a way that it actuates the on-off valves of various cooling modules independently of each other in order to set the individual pulse length and/or pulse frequency for each cooling module.

3. The cooling system according to claim 2, characterized in that the cooling system control unit is configured in such a way that it records the first temperature (T1) along one rotation (2Un+1) of the furnace shell through the impact area for a circumference of the furnace shell in a position-dependent manner, and said cooling system control unit adapts the pulse length and/or pulse frequency for the appertaining cooling module at least on the basis of the position-dependently recorded first temperatures (T1) in such a way that the hottest position (PH) on the circumference of the furnace shell is additionally cooled by a stronger cooling by the appertaining cooling module in the neighboring area (PH-U) surrounding the hottest position (PH).

4. The cooling system according to claim 2, characterized in that, after the setpoint temperature (ST) for a cooling module has been reached, the cooling system control unit interrupts the cooling by this cooling module until the first local temperature (T1) is above the setpoint temperature (ST) by at least a selectable value, preferably 30K.

5. The cooling system according to claim 1, characterized in that the fan nozzles are configured in such a way that they generate a fan-shaped cooling fluid jet that is at a first opening angle (W1) of at least 40 along the axis of rotation (R) of the furnace shell.

6. The cooling system according to claim 5, characterized in that the fan nozzles also have a second opening angle (W2) in the direction of rotation (DR) of the furnace shell that is at least 30, preferably at least 60, and in this context, the cooling system control unit is preferably provided to establish a short setting for the pulse length of the cooling fluid jet (4)at the same pulse frequencywhen the places of the furnace shell with small differences (DT1) from the setpoint temperature (ST) are passing through the impact area, and to establish a longer setting when the places of the furnace shell with larger differences (DT1) from the setpoint temperature (ST) are passing through the impact area.

7. The cooling system according to claim 1, characterized in that the distance (A1) between the adjacent cooling modules and the pressure of the cooling fluid for the cooling modules are set in such a way that the impact areas of the cooling fluids on the furnace shell for adjacent cooling modules touch each other, preferably without overlapping over each other.

8. The cooling system according to claim 1, characterized in that the cooling module also comprises a second heat sensor in order to measure a second local temperature (T2) of the furnace shell in the direction of rotation (DR) of the furnace shell behind the impact area and said heat sensor is provided in order to transmit (U2) the second local temperature (T2) to the cooling system control unit, for which purpose it is connected thereto, whereby the cooling system control unit is configured to actuate the on-off valve of each cooling module in such a way that the difference (DT2) between the first and second local temperatures (T1, T2) during one rotation is less than 10K, preferably less than 5K.

9. The cooling system according to claim 1, characterized in that the first heat sensor in the appertaining cooling module is arranged at a first position (P1), whereby an imaginary connecting line runs between the first position (P1) and the nozzle mid-point (D1) perpendicular to the axis of rotation (R) of the furnace shell and, if there is a second heat sensor as an additional heat sensor in the cooling module, this second heat sensor is arranged at a second position (P2) that is not the same as the first position (P1), whereby an imaginary connecting line runs between the first and second positions (P1, P2) perpendicular to the axis of rotation (R) of the furnace shell, and the first and second positions (P1, P2) are at least at the same distance (A2) from the furnace shell.

10. The cooling system according to claim 8, characterized in that the pulse length and/or pulse frequency of the cooling fluid jet is set in such a way that the second temperature (T2) for the place (S1) of the furnace shell where the first temperature (T1) had already been detected during the same rotation displays a difference from the setpoint temperature (ST) that is smaller by at least 0.5K than was the case with the first temperature (T1).

11. The cooling system according to claim 1, characterized in that the cooling system control unit is configured to emit a warning signal (SW) as soon as at least the difference (DT1) between the setpoint temperature (ST) and the first temperature (T1) is above a threshold value; preferably the warning signal (SW) is transmitted electronically to a rotary furnace control unit.

12. A rotary furnace, preferably a rotary cement furnace, having a cooling system according to claim 1.

13. A method for operating a cooling system for rotary furnaces according to claim 1 for cooling at least one section of a furnace shell comprising an arrangement of one or more cooling modules that, for the section of the furnace shell that is to be cooled, are arranged at a distance from the furnace shell, at least along the axis of rotation (R) of the furnace shell, each cooling module having an actuatable on-off valve and a fan nozzle that emits a pulsed fan-shaped cooling fluid jet, and also comprising at least a first heat sensor which serves to measure a first temperature (T1), comprising the following steps: measuring (M1) the first local temperature (T1) of the furnace shell at a place that is in front of the impact area of the cooling fluid as seen in the direction of rotation (DR) of the furnace shell; transmitting (U1) the first local temperature (T1) by means of the first heat sensor to a cooling system control unit that is connected thereto; setting (E) the pulse length and/or pulse frequency of the cooling fluid jet by means of the cooling system control unit through the actuation of the on-off valve of each of the cooling modules in accordance with a difference (DT1) between the first temperature (T1) and a setpoint temperature (ST) so that, after one rotation (2Un+1) of the furnace shell, the place (S1) of the furnace shell where the first local temperature (T1) was measured one rotation (2Un) before then has a first local temperature (T1) that is closer to the setpoint temperature (ST) than at the time of the preceding measurement, insofar as cooling fluid was applied onto the appertaining impact area during that particular rotation, whereby, however, the difference (DT1-U) between the first local temperatures (T1, T1) of these two measurements is less than 30K, preferably less than 15K; and applying (A) the cooling fluid from the outside onto the furnace shell in an impact area of the cooling fluid on the furnace shell, whereby, if there are several cooling modules, the adjacent cooling modules are arranged at a distance (A1) relative to each other and parallel to the axis of rotation (R) of the furnace shell in such a way that the impact areas contiguously cool the furnace shell along the axis of rotation (R), at least in the section that is to be cooled.

14. The method according to claim 13, whereby the cooling system control unit actuates the on-off valves of various cooling modules independently of each other in order to set (E) the individual pulse length and/or pulse frequency for each cooling module.

15. The method according to claim 14, whereby the cooling system control unit records the first temperatures (T1) along one rotation of the furnace shell through the impact area of the cooling fluid jet of the appertaining cooling module for a circumference of the furnace shell in a position-dependent manner, and said cooling system control unit adapts the pulse length and/or pulse frequency for the appertaining cooling module on the basis of the position-dependently recorded temperatures (T1) in such a way that the hottest position (PH) on the circumference of the furnace shell is additionally cooled by a stronger cooling by the appertaining cooling module in the neighboring area (PH-U) surrounding the hottest position (PH).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] These and other aspects of the present invention are presented in detail in the drawings as follows:

[0035] FIG. 1: a schematic depiction of a conventional rotary furnace (a) in a side view and (b) in a sectional view perpendicular to the axis of rotation;

[0036] FIG. 2: a rotary furnace with an embodiment of the cooling system according to the invention, in a top view from above;

[0037] FIG. 3: a rotary furnace with another embodiment of the cooling system according to the invention, in a sectional view perpendicular to the axis of rotation;

[0038] FIG. 4: an embodiment of the method according to the invention, for operating the cooling system according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0039] FIG. 1 shows a schematic depiction of a conventional rotary furnace 1 (a) in a side view and (b) in a sectional view perpendicular to the axis of rotation R. Rotary furnaces 1 are employed for continuous processes in process engineering. The rotary furnace 1 shown here comprises a cylindrical rotary tube which is several dozen meters long and that has a furnace shell 2 made of metal and which is rotated in a direction of rotation DR around its longitudinal axis as the axis of rotation R. In this context, the furnace shell 2 is slightly inclined, for instance, by 5, so that the rotation of the furnace shell 2 causes the material to be transported inside the rotary furnace 1 along the axis of rotation R of the furnace shell 2 from the higher inlet opening (inlet side) 2E to the lower outlet opening (outlet side) 2A. The material 61 that is to be processed, which is fed into the rotary furnace 1 at the inlet opening 2E, can vary and can comprise, for instance, solids, stones, slurries or powders. The requisite processing temperature can be established directly or indirectly in the rotary furnaces 1. When it comes to materials that call for a high processing temperature, the rotary furnace 1 as shown here is heated directly, for example, by a thermal lance 51 generated by a burner 5 situated at the outlet opening 2A of the rotary furnace 1, said lance being located approximately in the middle of the rotary furnace. Directly heated rotary furnaces 1 are used, for example, for cement production, for lime calcining, to melt ceramic glass, to melt down metals, for iron reduction, to produce activated carbon as well as for other applications. In this process, the directly heated rotary furnaces 1 are operated at very high temperatures. During cement production, for example, the raw materials, namely, lime and clay, are ground up and calcined in the rotary furnace 1 at approximately 1450 C. to form so-called clinker, as the material 62 emerging from the outlet opening 2A, and subsequently cooled off and further processed after leaving the rotary furnace 1.

[0040] Rotary furnaces 1 that are exposed to such high temperatures have a furnace shell 2 made of stainless steel or of high-temperature steel that can be exposed to temperatures of up to 550 C. or 950 C., respectively. Since the temperatures in the directly heated area are considerably higher, the inside of the furnace shell 2 made of steel is lined with high-temperature ceramic elements 7. In this context, the thickness of the lining 7 determines the temperature to which the steel shell 2 is exposed during the process. In order to prevent the furnace shell 2 from warping during operation due to the temperature load or in order to prevent damage to the inner lining that would cause the furnace shell 2 to bend or even melt, the furnace shell is cooled from the outside (not shown explicitly here). As a rule, the high-temperature ceramic elements 7 consist of ceramic tiles 71 that are arranged next to each other so as to be in contact with each other.

[0041] FIG. 2 shows a rotary furnace 1 with an embodiment of the cooling system 3 according to the invention, in a top view from above. In this embodiment, by way of example, the cooling system 3 for rotary furnaces 1 for cooling at least one section 21 of a furnace shell 21 comprises an arrangement of three cooling modules 31, 31, 31 for applying cooling fluid 4 from the outside onto the furnace shell 2 in an impact area 41 of the cooling fluid 4 on the furnace shell 2, whereby the cooling modules 31 in the section 21 of the furnace shell 2 that is to be cooled are arranged at least along the axis of rotation R of the furnace shell 2. The gray arrow here indicates that, aside from the cooling modules 31, 31, 31 shown here, in other embodiments, other cooling modules can also be arranged over the entire length of the rotary furnace 1 or of the furnace shell 2. Each cooling module 31, 31, 31 has an actuatable on-off valve 311 and a fan nozzle 312 by means of which a pulsed fan-shaped cooling fluid jet 4 is sprayed onto the furnace shell. For this purpose, adjacent cooling modules 31, 31, 31 are at a distance A1 relative to each other and parallel to the axis of rotation of the furnace shell R, said distance having been suitably selected as a function of the widening of the cooling-fluid jet by the fan nozzle 312, so that the impact areas 41 contiguously cool the furnace shell 2 along its axis of rotation R, at least in the section 21 that is to be cooled. For this purpose, each cooling module 31 comprises at least a first heat sensor 313 (see FIG. 3) which is connected to a cooling system control unit 32 via data lines 33, which serves to measure a first local temperature T1 of the furnace shell 2 at a place that is in front of the impact area 41 of the cooling fluid 4 as seen in the direction of rotation DR of the furnace shell 2, and which serves to transmit U1 the first local temperature T1 to the cooling system control unit 32 via the data lines 33. The cooling system control unit 32 is configured to actuate the on-off valve 311 of each of the cooling modules 31 via the data line 33 in accordance with a difference DT1 between the appertaining first local temperature T1 and a setpoint temperature ST in such a way thatby setting E the pulse length and/or pulse frequency of the cooling fluid jet 4 after one rotation n+1 of the furnace shell 2the place S1 of the furnace shell 2 where the first local temperature T1 was measured one rotation before (rotation n) then has a first local temperature T1 that is closer to the setpoint temperature ST than at the time of the preceding measurement, whereby, however, the difference DT1-U between the first local temperatures T1, T1 of these two measurements is less than 30K, preferably less than 15K. Regarding the features not explicitly mentioned here, reference is hereby made to FIGS. 3 and 4. The fan nozzles 312 are configured in such a way that they generate a fan-shaped cooling fluid jet 4 that has a first opening angle W1 of at least 40 along the axis of rotation R of the furnace shell 2. Therefore, in this embodiment, the cooling system control unit 32 is connected to the on-off valves 311 of various cooling modules 31, 31, 31 and configured in such a way that the cooling system control unit 32 actuates the on-off valves 311 of various cooling modules 31, 31, 31 independently of each other in order to set an individual pulse length and/or pulse frequency for each cooling module 31, 31, 31. In this context, the distance A1 between the adjacent cooling modules 31, 31, 31 is selected in such a way and the pressure of the cooling fluid 4 for the cooling modules 31, 31, 31 is set in such a way that the impact areas 41 of the cooling fluids 4 on the furnace shell 2 for adjacent cooling modules 31, 31, 31 touch, preferably without overlapping each other in this process. The distance of the fan nozzle to the furnace shell 2 can be suitably set as a function of the temperature of the furnace shell 2, of the line pressure used for the cooling fluid and of the first and/or second opening angles. Typical line pressures for the cooling fluid are, for instance, 3 bar to 6 bar.

[0042] In this embodiment, the cooling system 3 and the cooling system control unit 32 are configured to emit a warning signal SW as soon as at least the difference DT1 between the setpoint temperature ST and the first temperature T1 is above a threshold value. For this purpose, the cooling system control unit 32 is electronically connected to the rotary furnace control unit 11 by means of a data line indicated by a broken line, so that the warning signal SW can be automatically transmitted to the rotary furnace control unit 11.

[0043] FIG. 3 shows a rotary furnace 1 with another embodiment of the cooling system 3 according to the invention, in a sectional view perpendicular to the axis of rotation of the rotary furnace 1. In this context, the figure description is based essentially on the components of the cooling system 3 according to the invention that are not shown in FIG. 2. When it comes to the components mentioned here that are not depicted in FIG. 3, reference is made to FIG. 2. Aside from the first heat sensor 313 that is located at position P1 and that serves to measure the first local temperature T1 at the place S1 on the furnace shell 2 before the place S1 reaches the impact area of the cooling fluid on the furnace shell 2 owing to the rotation of the furnace shell 2 in the direction of rotation DR, the cooling module 31 also comprises a second heat sensor 314 that serves to measure a second local temperature T2 of the furnace shell 2 in the direction of rotation DR of the furnace shell 2 behind the impact area 41, which is indicated by the broken-line curved brackets. Both heat sensors 313, 314 are connected to the cooling system control unit 32, as shown in FIG. 2, in order to transmit U1, U2 the first and second local temperatures T1, T2, whereby the cooling system control unit 32 is provided for purposes of actuating the on-off valve 311 of each cooling modulehere the depicted cooling module 31in such a way that the difference DT2 between the first and second local temperatures T1, T2 during one rotation is less than 10K, preferably less than 5K. Here, however, the cooling system control unit sets the pulse length and/or the pulse frequency of the cooling-fluid jet 4 in such a way that the second temperature T2 for the place ST of the furnace shell 2 where the first temperature T1 was already detected during the same rotation displays a difference of at least 0.5K less relative to the setpoint temperature ST than the first temperature T1 did. The first heat sensor 313 here is arranged at a first position P1 whereby an imaginary connecting line between the first position P1 and the mid-point D1 of the nozzle runs perpendicular to the axis of rotation R of the furnace shell 2. The second heat sensor 314 is arranged at a second position at a distance from the first position, behind the impact area of the cooling fluid on the furnace shell 2 as seen in the direction of rotation of the furnace shell 2, whereby an imaginary connecting line between the first position and second positions P1,P2 runs perpendicular to the axis of rotation R of the furnace shell 2, and the first and second positions P1, P2 are at least at the same distance A2 to the furnace shell. Moreover, P1 and P2 can be selected in such a way that the temperature measurements are not influenced by the evaporating cooling fluid 4, for instance, by means of the shape and length of the fastening means 315 of the heat sensors 313, 314 on the cooling module 32.

[0044] The fan nozzle 312 shown here allows the cooling-fluid jet 4 to have, in addition to the first opening angle, a second opening angle W2 in the direction of rotation DR of the furnace shell 2 amounting to at least 30, preferably at least 60. Preferably, the cooling system control unit 32 here is provided to establish a short setting for the pulse length of the cooling fluid jet 4at the same pulse frequencywhen the places of the furnace shell 2 with small differences DT1 from the setpoint temperature ST are passing through the impact area 41, and to establish a longer setting when the places of the furnace shell 2 with larger differences DT1 from the setpoint temperature ST are passing through the impact area 41.

[0045] In this embodiment, by way of an example for problem scenarios that might occur, the heat-insulation layer 7, made of ceramic tiles 71, is shown on the inside of the furnace shell 2, whereby such a ceramic tile 71 is missing at the place 72, so that this place 72 is exposed without having any protection to the temperature that prevails inside the rotary furnace. Consequently, the outside of the furnace shell 2 at the place PH will become considerably hotter than at the places where the protective ceramic tiles 71 are still present on the inside. In order to nevertheless be able to sufficiently cool the hot place PH, in this embodiment, the cooling system control unit 32 is configured in such a way that it records the first local temperature T1 along one rotation 2Un+1 of the furnace shell through the impact area 41 for a circumference of the furnace shell 2 in a position-dependent manner, and said cooling system control unit 32 adapts the pulse length and/or pulse frequency for the appertaining cooling module 31 at least on the basis of the position-dependently recorded first temperatures T1 in such a way that the hottest position PH on the circumference of the furnace shell 2 is additionally cooled by a stronger cooling by the appertaining cooling module 31 in the neighboring area PH-U surrounding the hottest position PH. The neighboring area PH-U is indicated here by the broken-line arrow running along the direction of rotation. Naturally, the neighboring area PH-U also extends in the direction along the axis of rotation, which is not shown here.

[0046] FIG. 4 shows an embodiment of the method according to the invention, for operating the cooling system 3 according to the invention, whereby initially the first local temperature T1 of the furnace shell 2 is measured M1 in the direction of rotation DR of the furnace shell 2 as seen in front of the impact area 41 of the cooling fluid 4. Subsequently, the first local temperature T1 is transmitted U1 by the first heat sensor 313 to the cooling system control unit 32 that is connected to it and then stored there. The setpoint temperature ST is stored in the cooling system control unit 32. The difference DT1 between the first temperature T1 and the setpoint temperature ST is measured on the basis of the measured first local temperature T1. If the first local temperatures for all points on the circumference of the furnace shell for at least one rotation of the furnace shell 2 are already available, the difference DT1-U of the first temperatures T1, T1 between the current measurement M1 and the preceding measurement during the preceding rotation is also calculated for the same places S1 on the furnace shell 2. If the cooling module 31 comprises a second heat sensor 314, the difference DT2 between the first temperature T1 and the second temperature T2, which have been measured M2 by the second heat sensor 314 and transmitted U2 to the cooling system control unit 32, is also calculated. On the basis of the calculated differences DT1, DT2 and/or DT1-U, the cooling system control unit 32 sets E the pulse length and/or pulse frequency of the cooling-fluid jet 4 by actuating the on-off valve 311 of each of the modules 31, 31, 31 in accordance with a difference DT1, so that, after one rotation 2Un+1 of the furnace shell 2, the place S1 of the furnace shell 2 where the first local temperature T1 was measured one rotation before then exhibits a first local temperature T1 that is closer to the setpoint temperature ST than in the preceding measurement, whereby the difference DT1-U between the first local temperatures T1, T1 of these two measurements, however, is less than 30K, preferably less than 15K. Depending on the embodiment of the cooling system control unit 32 and on the components present, such as the second heat sensor 314, the differences DT2 and a minimum value for the furnace shell cooling are also taken into consideration for purposes of controlling the cooling process. Once the on-off valve 311 has been actuated in accordance with the evaluation of the temperature measurements, the on-off valve 311 and the fan nozzle 312 are employed to apply A the cooling fluid 4 from the outside onto the furnace shell 2 in an impact area 41 of the cooling fluid 4 onto the furnace shell 2, whereby adjacent cooling modules 31, 31, 31 are arranged at a distance A1 relative to each other and parallel to the axis of rotation R of the furnace shell 2 in such a way that the impact areas 41 contiguously cool the furnace shell 2 along the axis of rotation R, at least in the section 21 that is to be cooled. In this process, the cooling system control unit 32 in this embodiment controls the on-off valves 311 of various cooling modules 31, 31, 31 independently of each other in order to set E individual pulse lengths and/or pulse frequencies for each cooling module 31, 31, 31.

[0047] In this embodiment, the cooling system control unit 32 records the first temperatures T1 along one rotation of the furnace shell through the impact area 41 of the cooling fluid jet 4 of the appertaining cooling module 31, 31, 31 for a circumference of the furnace shell 2 in a position-dependent manner, as a result of which the cooling system control unit 32 identifies the hottest position PH on the furnace shell (if applicable several hot positions PH on the furnace shell) on the basis of the data and then adapts the pulse length and/or pulse frequency for the appertaining cooling module 31, 31, 31 through whose impact area 41 the hottest place PH or the hottest places PH pass, on the basis of these position-dependently recorded temperatures T1 in such a way that the hottest position PH on the circumference of the furnace shell 2 is additionally cooled by a stronger cooling by the appertaining cooling module 31, 31, 31 in the neighboring area PH-U surrounding the hottest position PH.

[0048] In another embodiment, after the setpoint temperature ST for a cooling module 31, 31, 31 has been reached, the cooling system control unit 32 interrupts the cooling by this cooling module 31, 31, 31 until the first local temperature T1 is above the setpoint temperature ST by at least a selectable value (switch-on threshold), preferably 30K. For instance, the setpoint temperature in a cement rotary furnace is 210 C., so that the switch-on threshold for a renewed cooling procedure would then be 240 C.

[0049] The embodiments shown here constitute merely examples of the present invention and consequently should not be construed in a limiting manner. Alternative embodiments that might be considered by the person skilled in the art are likewise encompassed by the scope of protection of the present invention.

LIST OF REFERENCE NUMERALS

[0050] 1 rotary furnace [0051] 11 rotary furnace control unit [0052] 2 furnace shell [0053] 2E inlet opening for the material that is to be processed [0054] 2A outlet opening for the processed material [0055] 2Un furnace shell after n rotations (before one rotation) [0056] 2Un+1 furnace shell after n+1 rotations (before one additional rotation) [0057] 21 section of the furnace shell that is to be cooled [0058] 3 cooling system according to the invention [0059] 31, 31, 31 cooling module [0060] 311 on-off valve in the cooling module [0061] 312 fan nozzle in the cooling module [0062] 313 first heat sensor [0063] 314 second heat sensor [0064] 315 fastening means for heat sensor(s) on the cooling module [0065] 32 cooling system control unit [0066] 33 data lines in the cooling system [0067] 34 cooling-fluid lines in the cooling system [0068] 4 cooling fluid, cooling-fluid jet [0069] 41 impact area of the cooling fluid on the furnace shell [0070] 5 burner of the rotary furnace [0071] 51 thermal lance [0072] 61 material that is to be processed by the rotary furnace [0073] 62 material be processed by the rotary furnace [0074] 7 heat-insulation layer on the inside of the furnace shell [0075] 71 ceramic tiles [0076] 72 ceramic tile missing in the heat-insulation layer [0077] A application of cooling fluid from the outside onto the furnace shell [0078] A1 distance of adjacent cooling modules relative to each other and parallel to the axis of rotation R [0079] A2 distance between the furnace shell and the first and/or second positions of the first and/or second heat sensors [0080] D1 mid-point of the nozzle [0081] DR direction of rotation of the furnace shell [0082] DT1 difference between the first temperature and the setpoint temperature [0083] DT2 difference between the first temperature and the second temperature during the same rotation of the furnace shell [0084] DT1-U difference between two first temperatures of the same places on the furnace shell after one rotation of the furnace shell [0085] E setting the pulse frequency and the pulse length of the cooling-fluid jet [0086] M1 measuring the first local temperature [0087] M2 measuring the second local temperature [0088] P1 position where the first heat sensor is located [0089] P2 position where the second heat sensor is located [0090] PH hottest position on the circumference of the furnace shell for a given impact area [0091] PH-U surroundings of the hottest position [0092] R axis of rotation of the furnace shell [0093] S1 place on the furnace shell where the first local temperature is measured [0094] ST setpoint temperature of the furnace shell [0095] SW warning signal emitted by the cooling system [0096] T1, T1 first temperature [0097] T2 second temperature [0098] U1 transmission of the first temperature to the cooling system control unit [0099] U2 transmission of the second temperature to the cooling system control unit [0100] W1 first opening angle of the cooling-fluid jet [0101] W2 second opening angle of the cooling-fluid jet