EP2947409A1 - Cooling system for rotary kilns - Google Patents

Abstract

The invention relates to a cooling system (3) for rotary kilns (1), a rotary kiln (1) with such a cooling system (3) and a method for operating such a cooling system (3). For this purpose, the cooling system (3) comprises an arrangement of one or more cooling modules (31, 31 ', 31 ") arranged in the section (21) of the furnace shell (2) to be cooled at least along the axis of rotation (R) of the furnace shell (2) wherein each cooling module (31) comprises a controllable switching valve (311) and a fan nozzle (312) for emitting a pulsed fan-shaped cooling liquid jet (4) and in the case of several cooling modules the adjacent cooling modules (31, 31 ', 31 ") at a distance ( A1) parallel to the axis of rotation (R) of the furnace shell (2) are arranged so that the impact areas (41) cool the furnace shell (2) along its axis of rotation (R) at least in the section to be cooled (21) gapless. Each cooling module (31, 31 ', 31 ") comprises at least one first heat sensor (313) connected to a cooling system controller (32) for measuring a first local temperature (T1) of the furnace shell (2) in the direction of rotation (DR) of the furnace shell (2). The cooling system controller (32) is configured to switch the switching valve (311) of each cooling module (31, 31 ', 31 ") according to a difference (DT1) between the respective first local temperature (T1) and a target temperature (ST) to control so that the pulse length and / or pulse frequency of the cooling liquid jet (4) are suitable that after one revolution (2Un + 1) of the furnace shell (2) the point (S1) of the furnace shell (2), at the one Rotation (2Un) before the first local temperature (T1) was measured, then a first local temperature (T1 '), which is closer to the target temperature (ST) than in the previous measurement, the difference (DT1-U) between the first local temperatures (T1, T1 ' ) of these two measurements is less than 30K, preferably less than 15K.

Description

Field of the invention

The invention relates to a cooling system for rotary kilns, to a rotary kiln with such a cooling system and to a method for operating such a cooling system.

Background of the invention

Rotary ovens are used for continuous processes in process engineering. A rotary kiln usually consists of a partly many meters or several tens of meters long cylindrical rotary kiln with a furnace shell usually made of metal. Here, the furnace shell is slightly inclined in order to bring about with the circulation of the furnace shell a transport of the material inside along the axis of rotation of the furnace shell in the furnace from the higher inlet side to the lower outlet side. The material to be processed can be different, for example solids, rocks, sludges or powders. The required process temperature can be generated directly or indirectly in the rotary kilns. For materials that require a high process temperature, the rotary kiln is heated directly, for example by a lance as a burner on the outlet side of the rotary kiln, which is located approximately centrally in the rotary tube. Direct heated rotary furnaces are used, for example, for cement production, lime burning, ceramic glass melting, metal melting, iron ore reduction, activated carbon production and other applications. The directly heated rotary kilns are operated at very hot temperatures. For example, in cement production, the raw materials, including limestone and clay, ground and fired in the rotary kiln at about 1450 ° C to so-called clinker and then cooled after leaving the rotary kiln and further processed.

Turning furnaces exposed to these high temperatures have a furnace shell made of stainless steel or high-temperature steel, which can be exposed to temperatures of up to 550 ° C or 950 ° C. As the temperatures In the field of direct heating are significantly higher, the furnace shell of steel is lined on its inside with a high-temperature ceramic. The thickness of the lining determines the temperature that the steel jacket feels during the process. In order for the furnace shell not to warp during operation due to thermal stress or damage to the inner lining to prevent bending or even melting of the furnace shell, the furnace shell is currently externally provided with air blowers located outside the kiln shell length outside the rotary kiln. cooled.

This cooling is complex and occupies a large space around the oven. In addition, such a fan cooling is very loud and consumes a lot of electrical energy, which is expensive. Should the noise pollution of the environment have to be reduced for noise protection reasons, the rotary furnaces would have to be operated in a sound-absorbing hall, which would not be advantageous because of the high process temperatures and would be very cost-intensive because of the building costs. Moreover, such fan cooling can neither detect nor individually cool strong local heating of the furnace shell.

It would therefore be desirable to have a rotary kiln cooling system that is simple and reliable to operate at a low noise level, permits local cooling control and reduces energy consumption.

Summary of the invention

It is an object of the present invention to provide a rotary kiln cooling system which is easily and reliably operable at a low noise level, enables local cooling control and reduces energy consumption.

This object is achieved by a cooling system for rotary kilns for cooling at least a portion of a furnace shell, comprising an arrangement of one or more cooling modules for applying cooling liquid from the outside to the furnace shell in an impact region of the cooling liquid on the furnace shell, wherein the cooling modules for the cooling Section of the furnace shell spaced at least along the axis of rotation of the furnace shell are arranged to the furnace shell, each cooling module comprises a controllable switching valve and a fan nozzle for delivering a pulsed fan-shaped cooling liquid jet and several cooling modules, the adjacent cooling modules are arranged at a distance parallel to the axis of rotation of the furnace shell to each other so that the impact areas the furnace shell along the axis of rotation at least in cooling section to be cooled, and wherein each cooling module comprises at least one connected to a cooling system control first heat sensor for measuring a first local temperature of the furnace shell in the direction of rotation of the furnace shell before the impact area of the cooling liquid and for transmitting the first local temperature to the cooling system control, and the cooling system control is configured to so the control valve of each cooling module according to a difference between the respective first local temperature and a target temperature n, that by adjusting the pulse length and / or pulse frequency of the cooling liquid jet after the rotation of the furnace shell, the location of the furnace shell on which one revolution previously the first local temperature was measured, then having a first local temperature, which is closer to the target temperature than at the previous measurement, provided that in the relevant revolution cooling liquid was applied to the respective impact area, but the difference between the first local temperatures of these two measurements is less than 30K, preferably less than 15K.

The cooling system is a system of cooling modules and a cooling system control, which is connected to the individual cooling modules via one or more data lines, preferably a data bus, in order to control the respective switching valves. The individual cooling modules are connected by one or more media lines with a cooling fluid supply of the cooling system. The media lines can be designed separately from the individual cooling modules or supply the cooling modules in parallel with cooling fluid via a central media line. For controlling the pulse lengths and pulse frequencies of the coolant jet, the switching valves within the cooling modules in front of the respective fan nozzle in the respective media lines are arranged at a suitable position. The individual components of the cooling system such as data or Media line (s) and the controllable switching valves can be selected by the skilled person for the particular application suitable, in particular adapted to the required flow rate of the cooling liquid. The switching valves can be operated by the cooling system control, for example, so that is switched back and forth between a fully open and a fully closed state, so that the flow rate of the coolant through the fan nozzle has idealized a rectangular profile. In contrast to continuous liquid jets, a pulsed jet of cooling liquid is used in the cooling system according to the invention, where cooling liquid pulses alternate with rest phases without cooling liquid between the pulses. This is advantageous, on the one hand to achieve a good cooling effect locally, without the cooling over the furnace shell along a circumference can be made too fast. Too rapid a cooling, for example, due to a continuous jet of cooling fluid would cause intolerable stresses in the furnace shell material and warp or bend the furnace shell, rendering the rotary kiln inoperative. But even layer stresses, which do not bend the rotary kiln, but lead to a detachment of the thermal insulation materials on the inside of the furnace shell, can have very negative consequences for the operation of the rotary kiln, as the furnace shell material at the points where it is unprotected inside the process temperature in Oven is exposed, can even melt. The latter also leads to the destruction of the rotary kiln. Such pulses of cooling fluid have a pulse length per pulse and a frequency of pulses per unit time. In this case, the average flow rate can be controlled both via the pulse length and via the frequency of the pulses (pulse frequency). Within a pulse is cooled continuously with the cooling liquid, while in the time between the respective pulses no cooling liquid impinges on the furnace shell. Only the cooling liquid of the next pulse cools the furnace shell further down. Thus, on the one hand, the short-term available maximum cooling power can be adjusted via the pulse length, while the temporally averaged cooling power is set via the pulse frequency relative to the pulse length. By varying these sizes different locations on the furnace shell can be cooled to different degrees, so that the desired cooling at each point of the furnace shell, on within a Oven jacket revolution cooling liquid is applied, adjusted individually and depending on the local temperatures and the mechanically compensated by the furnace shell material voltages due to the cooling and controlled. Any liquids that can reduce the surface temperature by means of impingement and evaporation on a hot surface and that have sufficiently low viscosity so that they can be sprayed through a nozzle can be used as cooling liquids. An embodiment of suitable cooling liquids is water.

The cooling system controller used for the control can be one or more suitable processors for evaluating the measurement data and for calculating the required pulse frequencies and pulse lengths depending on the location and time of the cooling modules and the furnace positions on the respective peripheries, one or more microcontrollers for controlling the switching valves and a suitable Storage medium for time and position-dependent storage of the temperature data include. The person skilled in the art is able to select the appropriate hardware components for the cooling system control. The setpoint temperature is stored in the cooling system control for further control and can optionally be changed by the operator of the rotary kiln. The target temperature represents a desired temperature of the furnace shell, are excluded in the mechanical changes of the furnace shell due to the material heating for the intended operating time or very unlikely.

To achieve a cooling effect by evaporation, the cooling liquid must impinge as reproducibly on the furnace shell. The line pressure required at a set distance between the fan nozzle and the furnace shell, so that the coolant jet can impinge on the intended impact area without interference from external influences such as wind, is suitably selected by the person skilled in the art. The fan nozzle can be arranged for example at a distance of 1 m to 1.5 m to the furnace shell. At line pressures in the coolant lines of 3 bar - 6 bar, the coolant jet jet strikes the furnace shell in a well-adjusted manner. In one embodiment, the fan nozzles are substantially perpendicular to Impact area aligned on the furnace shell. In other embodiments, other alignment and thus cooling liquid beam angles can also be selected. Fan nozzles here denote nozzles that expand at least in one plane a jet with an opening angle dependent on the nozzle.

The section to be cooled on the furnace shell may in one embodiment relate only to the area around the fire lance, but in other embodiments, the furnace shell may also be cooled along its entire length along the axis of rotation of the rotary kiln. The furnace shell here refers to the outer shell of the rotating furnace and is usually made of temperature-resistant steel, stainless steel or high temperature steel. Although the rotary kiln is cooled by the cooling system only locally in the impingement area, the continuous rotation of the rotary kiln and thus of the kiln shell results in cooling all points on the periphery of the kiln shell which pass through the impingement area of the cooling liquid of each cooling module during one rotation , Typical revolution times are 0.5 min - 1.0 min per revolution. Since the rotational speed is kept constant at rotary kilns, the respective position of a location on the kiln shell from the rotational speed and the respective time (for example, measurement time of the first temperature, application time of the cooling fluid, etc.) is clearly given and thus usable as a basis for the position-dependent cooling system control.

In another embodiment, the current rotational speed of the rotary kiln can be measured by a microcontroller, for example by means of marks on the furnace shell or by means of encoders as a sensor for the rotation angle of the furnace shell, which selects the skilled person skilled in the rotary kiln and the respective position of a point to be cooled be calculated from it. The marks or signals of the rotary encoder or encoders can be detected, for example, by a rotary kiln control and the furnace shell position calculated therefrom can be transmitted to the coolant control. In an alternative embodiment, the marks on the furnace shell or the signals of the rotary encoders are arranged by corresponding optical or electronic means of the cooling system, for example at one or more Cooling modules or running as a separate from the cooling modules rotation angle detection unit connected to the cooling system control detected and transmitted the resulting furnace shell position to the cooling system control via the data lines.

The thermal sensors used for the measurements of the first (and / or second temperature) may be any suitable sensors. For example, infrared sensors are used in the cooling system according to the invention. The vapor formed by evaporation of the cooling liquid on the furnace shell affects the temperature measurement only slightly, since the choice of the pulse frequency of the cooling liquid jet, the time evolution of the steam can be controlled.

In contrast to currently used air cooling systems, the cooling system according to the invention by using a cooling liquid to operate very quietly, since the application of cooling liquid on the furnace shell can be made almost noiseless and the evaporation noise compared to the other operating noise of the rotary kiln are negligible. In addition, for example, with water as the cooling liquid, a cooling capacity of 1 MW dissipated power with only a quantity of water less than 1.8 m ³ per hour. For a greater cooling capacity, the amount of cooling liquid per unit time would have to be increased accordingly, which would be possible without difficulty at the low required amount. For the same cooling capacity, one would have to circulate more than 30,000 m ^{3 of} air per hour in the case of air cooling. Thus, the cooling system according to the invention is resource and energy saving operable. Due to the easy and precise metering of the amount of applied cooling liquid with correspondingly adapted to the measured temperatures quantity profiles as a function of time, the resulting stresses in the furnace shell by cooling can be kept below critical values for the mechanical stability of the furnace shell. For example, cooling of a steel furnace jacket around 100K from its surroundings would result in a shrinkage of 1 mm per meter of circumference. For circumferences of 15 meters or more, this could result in a diameter shrinkage of 6 mm. This For mechanical reasons it would be absolutely necessary to avoid this. At a temperature difference of less than 30K, however, the shrinkage of the circumference would be less than 0.3 mm per meter of circumference. Here comes in addition that the cooling in the cooling system according to the invention does not take place simultaneously over the entire circumference, but is distributed along the circumference over a revolution, ie over 0.5 min - 1.0 min, which helps to further reduce the layer stresses.

By means of the cooling system according to the invention, rotary kilns can be cooled simply and reliably, the cooling system being operable at a low noise level, allowing a local cooling control and reducing the energy expenditure.

In one embodiment, the cooling system controller is connected to the switching valves of various cooling modules and configured to independently drive the switching valves of different cooling modules to set individual pulse length and / or pulse rate for each cooling module. As a result, the cooling for the respective circumference of the furnace shell can not only be position-dependent controlled in an impact area for a cooling module, but the cooling capacity of different cooling modules can be adapted to the rotary kiln conditions and necessities depending on the location of the respective different impact areas. In the area of the fire lance, for example, different cooling capacities are required than in the vicinity of the inlet opening for the raw material to be processed in the furnace, which has a substantially lower temperature there. Thus, the same cooling system according to the invention can be used individually for different rotary furnaces and operating phases or adapted to changed operating parameters of the furnace.

In one embodiment, the cooling system controller is configured to position-record the first temperature along a furnace shell rotation through the impingement region for a perimeter of the furnace shell and to adjust the pulse length and / or pulse rate for the particular cooling module based at least on the position-dependent recorded first temperatures the hottest position on the circumference of the furnace shell by a stronger Cooling by the relevant cooling module is additionally cooled in the ambient area surrounding the hottest position. Thus, the cooling system according to the invention can not only respond to the measured temperatures on the furnace shell following, but in advance as a function of the furnace shell position by means of recorded over the circumference of the first temperatures with increased ambient cooling to particularly cool points complementary respond.

In one embodiment, after reaching the setpoint temperature for a cooling module, the cooling system controller interrupts the cooling by this cooling module until the first local temperature is above the setpoint temperature by at least an adjustable value, preferably 30K. If the furnace shell is at or near the setpoint temperature, cooling may be dispensed with for a certain time interval for economic reasons in order to save resources.

In one embodiment, the fan nozzles are configured to produce a fan-shaped cooling fluid jet having a first opening angle of at least 40 ° along the axis of rotation of the rotary kiln. As a result, a cooling module can spray a larger area of the furnace shell with cooling fluid, so that the number of cooling modules is limited for complete cooling of the section to be cooled and the cooling system thereby manages with a smaller number of components for a predetermined size of the area to be cooled. At the same time the amount of cooling liquid is distributed over a wider impact area, so that the amount of cooling liquid per unit area on the furnace shell is easier to control and thus unwanted excessive cooling of a small area on the furnace shell is prevented. The fanning out of the cooling liquid jet can be configured via the selection and adjustment of the fan nozzle so that adjacent impact areas overlap slightly, since in the outer regions of the impact areas usually less amount of liquid per surface is applied than in the central region of the impingement of each fan nozzle. Thus, adjacent fan nozzles can complement each other in the outer regions of the impact surfaces when applying the cooling liquid. Even if the impact areas do not overlap, the areas still overlap adjacent cooling modules in which a cooling effect is achieved on the furnace shell, as this extends by means of heat conduction beyond the pure impact area addition. Such a cooling-liquid jet fanned out in the plane of the longitudinal direction of the rotary kiln may, for example, have a second opening angle of less than 10 ° in the direction perpendicular thereto (perpendicular to the rotational axis of the rotary kiln).

In another embodiment, one, several or all fan nozzles also have a second opening angle in the direction of rotation of the furnace shell (perpendicular to the axis of rotation of the furnace shell), which is at least 30 °, preferably at least 60 °. As a result, neighboring areas adjacent to one another in the direction of rotation can be locally overlapped by the same impingement area, which on the one hand distributes the cooling power over a larger area and, on the other hand, precooling subsequent areas which only then pass through the impingement area. The overlapping cooling distributes the local cooling capacity over a longer application time and thus reduces the local stresses in the furnace shell. In a preferred embodiment, the cooling system control is provided to set the pulse length of the coolant jet at the same pulse rate when passing the locations of the furnace shell with small differences to the target temperature by the impact area and longer when passing through the points of the furnace shell with larger differences from the target temperature by the impact area adjust.

In one embodiment, the distance between the adjacent cooling modules and a pressure of the cooling liquid for the cooling modules are adjusted so that the impact areas of the cooling liquids on the furnace jacket for adjacent cooling modules touch, preferably without overlapping. This ensures that the area to be cooled can be completely cooled with the least possible number of cooling modules.

In one embodiment, the cooling module further comprises a second thermal sensor for measuring a second local temperature of the furnace shell in the direction of rotation of the furnace shell behind the impact area, for transmission the second local temperature is provided to and connected to the cooling system controller, wherein the cooling system control is intended to control the switching valve of each cooling module so that the difference between the first and second local temperature during a revolution is less than 10K, preferably less than 5K , The second thermal sensor provides a reading of the local furnace jacket temperature directly after passing that point through the impingement area of the coolant. This gives the cooling system control a direct value for the cooling effect. By contrast, waiting for a complete revolution will only provide the value of typically 30s-60s (time of furnace shell rotation), whereby the comparison between the first temperature at revolution n and the first temperature will be one revolution later (revolution n + 1) due to the intervening heating of the Oven jacket at non-cooled points the value is also affected. With the measured second temperature as a supplementary measured value, the furnace shell cooling can be adapted even more precisely to the circumstances in order to avoid disadvantageous cooling effects.

In a further embodiment, the first heat sensor is arranged in the respective cooling module at a first position, wherein an imaginary connecting line between the first position and the nozzle center runs perpendicular to the axis of rotation of the furnace shell. In the case of the presence of a second heat sensor as an additional heat sensor in the cooling module of this second heat sensor is disposed at a second positions not equal to the first position, wherein an imaginary line connecting the first and second position perpendicular to the axis of rotation of the furnace shell and first and second positions at least the same distance have to the furnace shell. Thus, the measured values are taken with the first and second thermal sensors under the same spatial conditions or the first thermal sensor is directed to the center of the impact area. This center point is the point at which the largest amount of cooling fluid is applied to the impact area during a pulse and thus requires the greatest supervision. The first and / or second position of the heat sensors can be selected, for example, so that the cooling liquid evaporating on the furnace shell does not or only insignificantly through the area between the heat sensors and the Oven mantle pulls. Thus, the temperature measurement is no longer affected by the vapor evolution of the evaporating liquid.

In one embodiment, the pulse length and / or pulse frequency of the coolant jet is adjusted so that the second temperature for the location of the furnace shell at which the first temperature was already detected during the same revolution, at least 2K smaller difference from the target temperature than the first Temperature. This ensures that, in addition to avoiding stresses in the furnace shell, sufficient cooling of the furnace shell is nevertheless achieved.

In one embodiment, the cooling system control is configured to emit a warning signal as soon as at least the difference between setpoint temperature and first temperature is above a threshold temperature, preferably the warning signal is transmitted electronically to a rotary kiln control. Thus, with inadequate cooling of the rotary kiln, it can be protected by other process settings via the rotary kiln control. If the warning signal is transmitted automatically and electronically, the rotary kiln control can react automatically and without any time delay. The threshold temperature can also be stored and changed in the cooling system control. It depends on the particular application and the rotary kiln.

The invention also relates to a rotary kiln with a cooling system according to the invention. Rotary ovens, for example, are directly heated rotary kilns for lime burning, for melting ceramic glasses, for melting metals, for iron ore reduction, for activated carbon production and for other applications. In a preferred embodiment, the rotary kiln is a cement rotary kiln.

• Messen der ersten lokalen Temperatur des Ofenmantel in Drehrichtung des Ofenmantels gesehen vor dem Auftreffbereich der Kühlflüssigkeit;
• Übermittlung der ersten lokalen Temperaturen durch den ersten Wärmesensor an eine mit ihnen verbundene Kühlsystemsteuerung;
• Einstellung der Pulslänge und/oder Pulsfrequenz des Kühlflüssigkeitsstrahls mittels Ansteuerung des Schaltventils eines jeden Kühlmoduls durch die Kühlsystemsteuerung entsprechend einer Differenz zwischen der ersten Temperatur und einer Solltemperatur, so dass nach einer Umdrehung des Ofenmantels die Stelle des Ofenmantels, an der eine Umdrehung zuvor die erste lokale Temperatur gemessen wurde, dann eine erste lokale Temperatur aufweist, die näher an der Solltemperatur liegt als bei der vorangegangenen Messung, sofern in der betreffenden Umdrehung Kühlflüssigkeit auf den jeweiligen Auftreffbereich aufgebracht wurde, wobei die Differenz zwischen den ersten lokalen Temperaturen dieser beiden Messungen aber weniger als 30K, vorzugsweise weniger als 15K, beträgt; und
• Aufbringung der Kühlflüssigkeit von außen auf den Ofenmantel in einem Auftreffbereich der Kühlflüssigkeit auf dem Ofenmantel, wobei bei mehreren Kühlmodulen die benachbarten Kühlmodule in einem Abstand parallel zur Drehachse des Drehofens zueinander so angeordnet sind, dass die Auftreffbereiche den Ofenmantel entlang der Drehachse zumindest im zu kühlenden Abschnitt lückenlos kühlen.

The invention further relates to a method for operating a rotary kiln cooling system according to the invention for cooling at least a portion of a furnace shell comprising an arrangement of one or more cooling modules suitable for the section of the furnace shell to be cooled at least along the axis of rotation of the furnace shell spaced from the furnace shell, each cooling module comprises a controllable switching valve and a fan nozzle for delivering a pulsed fan-shaped cooling liquid jet and at least a first heat sensor for measuring a first temperature, comprising the steps

• Measuring the first local temperature of the furnace shell in the direction of rotation of the furnace shell in front of the impact area of the cooling liquid;
• Transmitting the first local temperatures through the first thermal sensor to a cooling system controller connected thereto;
• Adjustment of the pulse length and / or pulse frequency of the coolant jet by controlling the switching valve of each cooling module by the cooling system control according to a difference between the first temperature and a target temperature, so that after one revolution of the furnace shell, the location of the furnace shell at the one turn before the first local Temperature was measured, then has a first local temperature, which is closer to the target temperature than in the previous measurement, if in the relevant revolution, cooling liquid was applied to the respective impact area, the difference between the first local temperatures of these two measurements but less than 30K, preferably less than 15K; and
• Application of the cooling liquid from the outside to the furnace shell in an impact region of the cooling liquid on the furnace shell, wherein at several cooling modules, the adjacent cooling modules are arranged at a distance parallel to the axis of rotation of the rotary kiln to each other so that the impact areas the furnace shell along the axis of rotation at least in the section to be cooled to cool completely.

In one embodiment of the method, the cooling system control controls the switching valves of different cooling modules independently of each other for setting individual pulse length and / or pulse frequency for each cooling module.

In a further embodiment of the method, the cooling system controller records the first temperatures along a furnace shell rotation through the impact area of the coolant jet of the respective cooling module for a perimeter of the oven mantle, and adjusts the pulse length and / or pulse rate for the particular chiller module based on position-dependent recorded temperatures such that the hottest position on the periphery of the oven mantle is enhanced by greater cooling by the particular chiller module in which the hottest position (PH ) surrounding area is additionally cooled.

Brief description of the illustrations

Fig.1:

schematische Darstellung eines üblichen Drehofens (a) in seitlicher Ansicht und (b) im Schnitt senkrecht zur Drehachse;

Fig.2:

ein Drehofen mit einer Ausführungsform des erfindungsgemäßen Kühlsystems in Draufsicht von oben;

Fig.3:

Drehofen mit einer weitern Ausführungsform des erfindungsgemäßen Kühlsystems im Schnitt senkrecht zur Drehachse des Drehofens;

Fig.4:

eine Ausführungsform des erfindungsgemäßen Verfahrens zum Betreiben des erfindungsgemäßen Kühlsystems.

These and other aspects of the invention are shown in detail in the figures as follows:

Fig.1:

schematic representation of a conventional rotary kiln (a) in a side view and (b) in section perpendicular to the axis of rotation;

Figure 2:

a rotary kiln with an embodiment of the cooling system according to the invention in plan view from above;

Figure 3:

Rotary kiln with a further embodiment of the cooling system according to the invention in section perpendicular to the axis of rotation of the rotary kiln;

Figure 4:

an embodiment of the method according to the invention for operating the cooling system according to the invention.

Detailed description of the embodiments

Fig.1 shows a schematic representation of a conventional rotary kiln 1 (a) in a side view and (b) in section perpendicular to the rotation axis R. rotary kilns 1 are used for continuous processes in process engineering. The rotary kiln 1 shown here comprises a many ten-meter-long cylindrical rotary tube with a furnace shell 2 made of metal, which is rotated about its longitudinal axis as a rotation axis R in a rotational direction DR. Here, the furnace shell 2 is slightly inclined, for example by 5 °, with the circulation of the furnace shell 2 a transport of the material inside along the axis of rotation R of the furnace shell 2 in the rotary kiln 1 from the higher inlet opening (inlet side) 2E to the lower outlet opening (outlet side) 2A bring about. The material to be processed 61, which is introduced into the rotary kiln 1 on the inlet port 2E, may be different, for example, solids, rocks, sludges or powders. The required process temperature can be generated directly or indirectly in the rotary kiln 1. For materials that require a high process temperature, the rotary kiln 1 as shown here directly, for example, by a fire lance 51 generated by a burner 5 at the outlet opening 2A of the rotary kiln 1, which is arranged approximately centrally in the rotary tube heated. Direct heated rotary furnaces 1 are used, for example, for cement production, lime burning, ceramic glass melting, metal melting, iron ore reduction, activated carbon production and other applications. The directly heated rotary kilns 1 are operated at very hot temperatures. For example, in cement production, the raw materials are ground limestone and clay and fired in rotary kiln 1 at about 1450 ° C to so-called clinker as emerging from the outlet opening 2A material 62 and then cooled after leaving the rotary kiln 1 and further processed.

Turning furnaces 1, which are exposed to these high temperatures, have a furnace shell 2 made of stainless steel or high-temperature steel, which can be exposed to temperatures of up to 550 ° C or 950 ° C. Since the temperatures in the region of direct heating are significantly higher, the furnace shell 2 made of steel is lined on its inside with a high-temperature ceramic 7. The thickness of the lining 7 determines the temperature that the steel jacket 2 feels during the process. So that the furnace shell 2 does not warp in the course of operation due to the temperature load or damage to the inner lining does not lead to bending or even melting of the furnace shell 2, the furnace shell is cooled from the outside (not explicitly shown here). The high-temperature ceramic 7 is usually formed of ceramic tiles 71, which are arranged in juxtaposition in contact with each other.

Fig.2 shows a rotary kiln 1 with an embodiment of the cooling system 3 according to the invention in plan view from above. The cooling system 3 for rotary kilns 1 for cooling at least one section 21 of a furnace shell 2 comprises in this embodiment, as an example, an arrangement of three cooling modules 31, 31 ', 31 ". for applying cooling liquid 4 from the outside to the furnace shell 2 in an impact region 41 of the cooling liquid 4 on the furnace shell 2, wherein the cooling modules 31 are arranged in the section 21 of the furnace shell 2 to be cooled at least along the axis of rotation R of the furnace shell 2. The gray arrow indicates that, in addition to the cooling modules 31, 31 ', 31 "shown here, other cooling modules can also be arranged over the entire length of the rotary kiln 1 or the furnace shell 2. In other embodiments, each cooling module 31, 31', 31" includes a controllable switching valve 311 and a fan nozzle 312, via which a pulsed fan-shaped cooling liquid jet 4 is sprayed onto the furnace shell. Adjacent cooling modules 31, 31 ', 31 "have for this purpose a distance A1, suitably selected as a function of the widening of the cooling liquid jet by the fan nozzle 312, parallel to the axis of rotation R of the furnace shell 2, such that the impact areas 41 surround the furnace shell 2 along its axis of rotation R, For this purpose, each cooling module 31 comprises at least one first heat sensor 313 connected to a cooling system controller 32 via data lines 33 (see FIG Figure 3 ) for measuring a first local temperature T1 of the furnace shell 2 in the direction of rotation DR of the furnace shell 2 before the impingement region 41 of the cooling liquid 4 and for transmitting U1 the first local temperature T1 via the data lines 33 to the cooling system controller 32. The cooling system controller 32 is designed to to control the switching valve 311 of each cooling module 31 via the data line 33 according to a difference DT1 between the respective first local temperature T1 and a target temperature ST such that by setting E the pulse length and / or pulse frequency of the cooling liquid jet 4 after one revolution n + 1 of the furnace shell 2 the location S1 of the furnace shell 2, at which one revolution previously (revolution n) the first local temperature T1 was measured, then a first local temperature T1 ', which is closer to the target temperature ST than in the previous measurement, the difference DT1-U between the first local temperatures T1, T1 'd but less than 30K, preferably less than 15K, of these two measurements. For the features not explicitly shown here is on FIG. 3 and 4 directed. The fan nozzles 312 are designed such that they produce a fan-shaped cooling liquid jet 4, which has a first opening angle W1 of has at least 40 ° along the axis of rotation R of the rotary kiln 2. The cooling system controller 32 in this embodiment is connected to the switching valves 311 of various cooling modules 31, 31 ', 31 "and configured to independently switch the switching valves 311 of various cooling modules 31, 31', 31" to set individual pulse length and / or pulse frequency For each cooling module 31, 31 ', 31 ", the distance A1 between the adjacent cooling modules 31, 31', 31" is selected and a pressure of the cooling liquid 4 for the cooling modules 31, 31 ', 31 "is set so that the impact areas 41 of the cooling liquids 4 on the furnace shell 2 for adjacent cooling modules 31, 31 ', 31 "touch, preferably without overlapping. The distance of the fan nozzle to the furnace shell 2 can be suitably adjusted depending on the temperature of the furnace shell 2, the line pressure used for the cooling liquid and the first and / or second opening angle. Typical line pressures for the cooling liquid are for example 3 bar - 6 bar.

In this embodiment, the cooling system 3 and the cooling system controller 32 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 temperature. For this purpose, the cooling system controller 32 is electronically connected via a data line shown in dashed lines with the rotary kiln control 11 in order to be able to transmit the warning signal SW to it automatically.

Figure 3 shows a rotary kiln 1 with a further embodiment of the cooling system 3 according to the invention in section perpendicular to the axis of rotation of the rotary kiln 1. Here, the figure description is substantially to the in Fig. 2 not shown components of the cooling system 3 according to the invention aligned. For the components mentioned here that are not in FIG. 3 are shown is on Fig.2 directed. In addition to the first heat sensor 313 arranged at position P1 for measuring the first local temperature T1 at the point S1 on the furnace shell 2 before the point S1 reaches the impact area of the cooling liquid on the furnace shell 2 by rotation of the furnace shell 2 in the direction of rotation DR, the cooling module comprises 31 further includes a second thermal sensor 314 for measuring 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, indicated by the dashed curved bracket. Both heat sensors 313, 314 are for transmitting U1, U2 of the first and second local temperatures T1, T2, as in FIG Fig.2 shown connected to the cooling system controller 32, wherein the cooling system controller 32 is provided to the switching valve 311 of each cooling module, here the cooling module 31 shown to drive so that the difference DT2 between first and second local temperature T1, T2 during a revolution less than 10K , preferably less than 5K. However, the cooling system control adjusts the pulse length and / or pulse frequency of the coolant jet 4 in such a way that the second temperature T2 for the point ST of the furnace shell 2 at which the first temperature T1 was already detected during the same revolution is increased by at least 0.5 The first heat sensor 313 is arranged at a first position P1, wherein an imaginary connecting line between the first position P1 and nozzle center D1 extends perpendicular to the axis of rotation R of the furnace shell 2. The second heat sensor 314 is arranged at a second position remote from the first position behind the impact area of the cooling liquid on the furnace shell 2 in the direction of rotation of the furnace shell 2, wherein an imaginary line connecting first and second position P1, P2 perpendicular to the axis of rotation R of the furnace shell. 2 runs and first and second positions P1, P2 have at least the same distance A2 to the furnace shell. Furthermore, P1 and P2 can be chosen so that the temperature measurements are not influenced by the evaporating cooling liquid 4, for example via the shape and length of the fastening means 315 of the heat sensors 313, 314 on the cooling module 32.

The fan nozzle 312 shown here allows for the coolant jet 4 in addition to the first opening angle a second opening angle W2 in the direction of rotation R of the furnace shell 2, which is at least 30 °, preferably at least 60 °. Preferably, the cooling system control 32 is provided to briefly set the pulse length of the coolant jet 4 at the same pulse rate during passage of the locations of the furnace shell 2 with small differences DT1 to the target temperature ST by the impact area 41 and To set the passage of the furnace shell 2 with larger differences DT1 to the target temperature ST by the impact area 41 longer.

In this embodiment, as an example of possible problem cases arising, the heat insulating layer 7, made of ceramic tiles 71, shown on the inside of the furnace shell 2, wherein at the point 72 such a ceramic tile 71 is missing, so that this point 72 of the temperature inside the rotary kiln without Protection is exposed. Thus, the furnace shell 2 will heat much more outside at the point PH than at the points where on the inside protective ceramic tiles 71 continue to exist. Nevertheless, in order to sufficiently cool this hot spot PH, in this embodiment, the cooling system controller 32 is configured to position-record the first temperature T1 along a furnace shell rotation 2Un + 1 through the landing area 41 for a circumference of the furnace shell 2, and / or or pulse frequency for the respective cooling module 31 at least on the basis of the position-dependent recorded first temperatures T1 so adapted that the hottest position PH on the periphery of the furnace shell 2 by a stronger cooling by the cooling module 31 in the hottest position PH surrounding surrounding area PH-U additionally cooled becomes. The surrounding area PH-U is indicated here by the dashed arrow along the direction of rotation. Of course, the surrounding area PH-U also extends in the direction along the rotation axis, which is not shown here.

Figure 4 shows an embodiment of the method according to the invention for operating the cooling system 3 according to the invention, wherein initially the first local temperature T1 of the furnace shell 2 in the direction of rotation DR of the furnace shell 2 is measured before the impact region 41 of the cooling liquid 4 measured M1. Subsequently, the first local temperature T1 is transmitted by the first heat sensor 313 to the cooling system controller 32 connected to it U1 and stored there. In the cooling system controller 32, the target temperature 32 is deposited. On the basis of the measured first local temperature T1, the difference DT1 between the first temperature T1 and the setpoint temperature ST is calculated. If the first local temperatures already exist for all points in one revolution of the furnace shell for at least one rotation of the furnace shell 2, the difference also becomes DT1-U of the first temperatures T1, T1 'between the current measurement M1 and the previous measurement in the previous revolution for the same locations S1 on the furnace shell 2 calculated. If the cooling module 31 includes a second heat sensor 314, the difference DT2 between the first temperature T1 and the M2 measured by the second heat sensor 314 and the second system temperature T2 transmitted to the cooling system controller 32 is also calculated. Based on the calculated differences DT1, DT2 and / or DT1-U, the cooling system controller 32 adjusts the pulse length and / or pulse frequency of the cooling liquid jet 4 by driving the switching valve 311 of each cooling module 31, 31 ', 31 "corresponding to a difference DT1, E after a revolution 2Un + 1 of the furnace shell 2, the point S1 of the furnace shell 2 at which a revolution 2Un previously the first local temperature T1 was measured, then a first local temperature T1 ', which is closer to the target temperature ST than in the previous However, the difference DT1-U between the first local temperatures T1, T1 'of these two measurements is less than 30K, preferably less than 15 K. Depending on the embodiment of the cooling system controller 32 and the existing components such as the second thermal sensor 314, the Differences DT2 and a minimum value for the furnace shell cooling are taken into account for controlling the cooling process Switching valve 311 was driven according to the evaluation of the temperature measurements, the cooling liquid 4 is applied from the outside to the furnace shell 2 in an impingement region 41 of the cooling liquid 4 on the furnace shell 2 via switching valve 311 and fan nozzle 312, wherein adjacent cooling modules 31, 31 ', 31 " are arranged at a distance A1 parallel to the axis of rotation R of the rotary kiln 2 to each other so that the impact areas 41 cool the furnace shell 2 along the axis of rotation R at least in the section to be cooled 21 gapless. In this embodiment, the cooling system controller 32 controls the switching valves 311 of different cooling modules 31, 31 ', 31 "independently of one another for setting E individual pulse lengths and / or pulse frequencies for each cooling module 31, 31', 31".

In this embodiment, the cooling system controller 32 draws the first temperatures T1 along a furnace shell rotation through the impingement region 41 of the cooling liquid jet 4 of the respective cooling module 31, 31 ', 31 "for one Circumference of the furnace shell 2 depending on position, whereby the cooling system controller 32 from the data identifies the hottest position PH on the furnace shell (possibly several hot positions PH on the furnace shell) and fits pulse length and / or pulse frequency for the respective cooling module 31, 31 ', 31 " , whose impact area 41 is traversed by the hottest point PH or the hot spots PH, due to these position-dependent recorded temperatures T1 so that the hottest position PH on the circumference of the furnace shell 2 by a greater cooling by the respective cooling module 31, 31 ', 31 "in which the hottest position PH surrounding surrounding area PH-U is additionally cooled.

In a further embodiment, the cooling system controller 32 additionally interrupts the cooling by this cooling module 31, 31 ', 31 "after reaching the setpoint temperature ST for a cooling module 31, 31', 31" until the first local temperature T1 has at least an adjustable value ( Switch-on threshold), preferably 30 K, is above the setpoint temperature ST. For example, the setpoint temperature for a cement rotary kiln is 210 ° C, the switch-on threshold for re-cooling would then be 240 ° C.

The embodiments shown herein are only examples of the present invention and therefore should not be considered as limiting. Alternative embodiments contemplated by one skilled in the art are equally within the scope of the present invention.

List of reference numbers

1

rotary kiln

11

Rotary kiln control

2

furnace shell

2E

Inlet opening for the material to be processed

2A

Outlet opening for the machined material

2un

Oven mantle after n turns (one revolution before)

2un + 1

Oven jacket after n + 1 revolutions (one more revolution)

21

to be cooled section of the furnace shell

3

Cooling system according to the invention

31, 31 ', 31 "

cooling module

311

Switching valve in the cooling module

312

Fan nozzle in the cooling module

313

first heat sensor

314

second heat sensor

315

Fastener for heat sensor (s) on the cooling module

32

Cooling system control

33

Data lines in the cooling system

34

Coolant pipes in the cooling system

4

Coolant, coolant jet

41

Impact area of the coolant on the furnace shell

5

Burner of the rotary kiln

51

Firelance

61

material to be processed by the rotary kiln

62

the material processed by the rotary kiln

7

heat-insulating layer on the inside of the oven shell

71

tiles

72

missing ceramic tile in the heat-insulating layer

A

Application of cooling fluid from the outside to the furnace shell

A1

Distance between adjacent cooling modules parallel to the axis of rotation R

A2

Distance between the furnace shell and the first and / or second position of the first and / or second thermal sensor

D1

Nozzle center

DR

Direction of rotation of the furnace shell

DT1

Difference between the first temperature and the setpoint temperature

DT2

Difference between first and second temperature during the same circulation of the furnace shell

DT1-U

Difference between two first temperatures of the same places on the furnace shell after one revolution of the furnace shell

e

Setting the pulse frequency and pulse length of the coolant jet

M1

Measuring the first local temperature

M2

Measuring the second local temperature

P1

Position at which the first thermal sensor is arranged

P2

Position at which the second thermal sensor is arranged

PH

Hottest position on the circumference of the furnace shell for an impact area

PH-U

Environment of the hottest position

R

Rotary axis of the furnace shell

S1

Place on the oven mantle where the first local temperature is measured

ST

Target temperature of the furnace shell

SW

Warning signal emitted by the cooling system

T1, T1 '

first temperature

T2

second temperature

U1

Transmitting the first temperature to the cooling system controller

U2

Transmitting the second temperature to the cooling system controller

W1

first opening angle of the coolant jet

W2

second opening angle of the coolant jet

Claims (15)

A cooling system (3) for rotary kilns (1) for cooling at least a portion (21) of a furnace shell (2), comprising an arrangement of one or more cooling modules (31, 31 ', 31 ") for applying (A) cooling liquid (4 ) from the outside on the furnace shell (2) in an impingement region (41) of the cooling liquid (4) on the furnace shell (2), wherein the cooling modules (31, 31 ', 31 ") for the section (21) of the furnace shell to be cooled ( 2) at least along the axis of rotation (R) of the furnace shell (2) spaced from the furnace shell (2) are arranged, each cooling module (31) comprises a controllable switching valve (311) and a fan nozzle (312) for delivering a pulsed fan-shaped cooling liquid jet (4) and in the case of a plurality of cooling modules (31, 31 ', 31 "), the adjacent cooling modules (31, 31', 31") are arranged at a distance (A1) parallel to the axis of rotation (R) of the furnace shell (2) relative to each other such that the impact areas (41) the furnace shell (2) along its axis of rotation (R) at least in küh Cooling lenden section (21) gapless and each cooling module (31, 31 ', 31 ") at least one connected to a cooling system controller (32) first heat sensor (313) for measuring a first local temperature (T1) of the furnace shell (2) in the direction of rotation (DR) of the furnace shell (2) as seen in front of the impingement region (41) of the cooling liquid (4) and for transmission (U1) of the first local temperature (T1) to the cooling system controller (32), and the cooling system controller (32) is configured thereto to control the switching valve (311) of each cooling module (31, 31 ', 31 ") according to a difference (DT1) between the respective first local temperature (T1) and a setpoint temperature (ST) such that by setting (E) the pulse length and / or pulse frequency of the coolant jet (4) after one revolution (2Un + 1) of the furnace shell (2) the location (S1) of the furnace shell (2) at which one revolution (2Un) previously the first local temperature (T1) was measured , then a first local Te Temperature (T1 '), which is closer to the target temperature (ST) than in the previous measurement, if in the relevant revolution, cooling liquid was applied to the respective impact area, wherein the difference (DT1-U) but is less than 30K, preferably less than 15K, between the first local temperatures (T1, T1 ') of these two measurements. The cooling system (3) according to claim 1,
characterized,
in that the cooling system controller (32) is connected to the switching valves (311) of different cooling modules (31, 31 ', 31 ") and configured to (32) switch the switching valves (311) of different cooling modules (31, 31', 31") independently of each other for setting individual pulse length and / or pulse frequency for each cooling module (31, 31 ', 31 ") drives. The cooling system (3) according to claim 2,
characterized,
in that the cooling system controller (32) is designed such that it records position-dependent the first temperature (T1) along a furnace shell rotation (2Un + 1) through the impact area (41) for a circumference of the furnace shell (2) and measures the pulse length and / or pulse frequency for the respective cooling module (31, 31 ', 31 ") at least on the basis of the position-dependent recorded first temperatures (T1) so that the hottest position (PH) on the circumference of the furnace shell (2) by a stronger cooling by the respective cooling module ( 31, 31 ', 31 ") in which the hottest position (PH) surrounding the surrounding area (PH-U) is additionally cooled. The cooling system (3) according to one of claims 2 or 3,
characterized,
that the cooling system controller (32) after reaching the set temperature '' cooling by this cooling module (31, 31 (, 31, 31 (ST) for a cooling module 31, 31) "') as long as interrupts, until the first local temperature (T1) at least by an adjustable value, preferably 30 K, above the setpoint temperature (ST). The cooling system (3) according to one of the preceding claims,
characterized,
in that the fan nozzles (312) are designed such that they produce a fan-shaped coolant jet (4) having a first opening angle (W1) of at least 40 ° along the rotation axis (R) of the rotary kiln (2). The cooling system according to claim 5,
characterized,
in that the fan nozzles (312) additionally have a second opening angle (W2) in the direction of rotation (R) of the furnace shell (2) which is at least 30 °, preferably at least 60 °, preferably the cooling system controller (32) is provided for the pulse length the cooling liquid jet (4) at the same pulse rate when passing through the points of the furnace shell (2) with small differences (DT1) to set temperature (ST) by the impingement (41) short and when passing through the positions of the furnace shell (2) with larger differences ( DT1) to set temperature (ST) by the impact area (41) longer. The cooling system (3) according to one of the preceding claims,
characterized,
in that the distance (A1) between the adjacent cooling modules (31, 31 ', 31 ") and a pressure of the cooling liquid (4) for the cooling modules (31, 31', 31") are set such that the impact areas (41) the cooling liquids (4) on the furnace shell (2) for adjacent cooling modules (31, 31 ', 31 ") touch, preferably without overlapping. The cooling system (3) according to one of the preceding claims,
characterized,
in that the cooling module (31, 31 ', 31 ") furthermore has a second heat sensor (314) for measuring 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) comprising means for communicating (U2) the second local temperature (T2) to and connected to the cooling system controller (32), the cooling system controller (32) provided therefor is to control the switching valve (311) of each cooling module (31, 31 ', 31 ") so that the difference (DT2) between first and second local temperature (T1, T2) during one revolution is less than 10K, preferably less than 5K , The cooling system (3) according to one of the preceding claims,
characterized,
that the first thermal sensors (313) is arranged in each cooling module (31, 31 ', 31 ") at a first position (P1), wherein an imaginary connecting line between the first position (P1) and the nozzle center (D1) perpendicular to the axis of rotation (R) of the furnace shell (2) and in the case of the presence of a second heat sensor (314) as an additional heat sensor in the cooling module (31, 31 ', 31 "), this second thermal sensor (314) at a second positions (P2) not equal to the first position (P1 ), wherein an imaginary connecting line between first and second position (P1, P2) is perpendicular to the axis of rotation (R) of the furnace shell (2) and first and second positions (P1, P2) have at least the same distance (A2) to the furnace shell , The cooling system (3) according to one of claims 8 or 9,
characterized,
in that the pulse length and / or pulse frequency of the coolant jet (4) is set such that the second temperature (T2) for the location (ST) of the furnace shell (2) at which the first temperature (T1) has already been detected during the same revolution , a smaller by at least 0.5 K difference to the target temperature (ST) identifies as the first temperature (T1). The cooling system (3) according to one of the preceding claims,
characterized,
in that the cooling system controller (32) is designed to emit a warning signal (SW) as soon as at least the difference (DT1) between setpoint temperature (ST) and first temperature (T1) is above a threshold temperature, preferably the warning signal (SW) electronically becomes a Rotary kiln control (11) transmitted. Rotary kiln (1), preferably Zementdrehofen, with a cooling system (3) according to claim 1. Method for operating a cooling system (3) for rotary kilns (1) according to claim 1 for cooling at least one section (21) of a furnace shell (2), comprising an arrangement of one or more cooling modules (31, 31 ', 31 ") suitable for the cooling section (21) of the furnace shell (2) spaced from the furnace shell (2) at least along the axis of rotation (R) of the furnace shell (2) are arranged, each cooling module (31, 31 ', 31 ") a controllable switching valve (311) and a fan nozzle (312) for emitting a pulsed fan-shaped cooling liquid jet (4) and at least one first thermal sensor (313) for measuring a first temperature (T1), comprising the steps - Measuring (M1) the first local temperature (T1) of the furnace shell (2) in the direction of rotation (DR) of the furnace shell (2) seen in front of the impingement region (41) of the cooling liquid (4); - transmitting (U1) the first local temperatures (T1) through the first thermal sensor (313) to a cooling system controller (32) connected thereto; - Setting (E) the pulse length and / or pulse frequency of the cooling liquid jet (4) by controlling the switching valve (311) of each cooling module (31, 31 ', 31 ") by the cooling system control (32) corresponding to a difference (DT1) between the first Temperature (T1) and a setpoint temperature (ST), so that after one revolution (2Un + 1) of the furnace shell (2) the point (S1) of the furnace shell (2), at one revolution (2Un) before the first local temperature ( T1), then has a first local temperature (T1 ') which is closer to the setpoint temperature (ST) than in the previous measurement, if cooling liquid was applied to the respective impact area in the relevant revolution, the difference (DT1- U) between the first local temperatures (T1, T1 ') of these two measurements is less than 30K, preferably less than 15K; and - Application (A) of the cooling liquid (4) from the outside to the furnace shell (2) in an impingement region (41) of the cooling liquid (4) on the furnace shell (2), wherein at several cooling modules, the adjacent cooling modules (31, 31 ', 31 ") at a distance (A1) parallel to the rotation axis (R) of the rotary kiln (2) are arranged to each other that the impact areas (41) the furnace shell (2) along the axis of rotation (R) at least in the section to be cooled (21) gapless cool. The method of claim 13, wherein the cooling system controller (32) independently controls the switching valves (311) of different cooling modules (31, 31 ', 31 ") to set (E) individual pulse length and / or pulse rate for each cooling module (31, 31', 31 "). The method of claim 14, wherein the cooling system controller (32) measures the first temperatures (T1) along a furnace shell rotation through the impingement region (41) of the cooling liquid jet (4) of the respective cooling module (31, 31 ', 31 ") for a perimeter of the furnace shell (FIG. 2) records position-dependent and pulse length and / or pulse rate for the respective cooling module (31, 31 ', 31 ") due to the position-dependent recorded temperatures (T1) so adapted that the hottest position (PH) on the circumference of the furnace shell (2) greater cooling by the relevant cooling module (31, 31 ', 31 ") in which the hottest position (PH) surrounding the surrounding area (PH-U) is additionally cooled.

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