EP3205965A1 - Adaptation of rotating furnace forms to target forms in rotating furnaces - Google Patents

Abstract

The invention relates to a cooling system (3) for a rotary kiln (1) rotating along an axis of rotation (R) for local adaptation of a present rotary kiln mold (VF) to a desired shape (SF), to a rotary kiln (1) having such a cooling system (3) and to a corresponding method with such a cooling system (3), which comprises an arrangement of one or more cooling modules (31, 31 ') for applying (130) cooling liquid (4) from the outside to the rotating furnace shell (2). in an impingement region (22) in a section (21) encircling the furnace shell (2) for local thermal deformation of the furnace shell (2) in the impingement region (22), the cooling module (s) (31, 31 ') being spaced apart to the furnace shell (2) are arranged and each comprise a controllable switching valve (311) and a fan nozzle (312) for emitting a pulsed fan-shaped cooling liquid jet (4), and wherein the cooling system (3) at least one Messeinhei t (35) with at least one fixedly arranged measuring sensor (36) suitable for the continuous determination of distances (A) in a predetermined direction between the measuring sensor (36) and the rotating furnace shell (2) in the circumferential section (21) and for calculating a location-dependent difference (D) between the present rotary kiln shape (VF) and the target shape (SF) calculated from the determined distances (A), wherein a cooling system controller (32) based on the location-dependent difference (D), the switching valve (311) for applying ( 130) of the cooling liquid (4) so that by means of adjustment (120) of a pulse length and / or a pulse frequency of the cooling liquid jet (4), the present rotary kiln mold (VF) is at least in the impingement region (22) of the desired shape (SF) adjusted.

Description

Field of the invention

The invention relates to a cooling system for a rotary kiln rotating along a rotation axis for the local adaptation of a present rotary kiln shape to a desired shape, to a rotary kiln with such a cooling system and to a corresponding method with 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.

Rotary yards that are exposed to these high temperatures have one Oven jacket made of stainless steel or high-temperature steel, which can be exposed to temperatures between 250 ° C and 500 ° C. Since the temperatures in the field of direct heating are significantly higher, the furnace shell made of steel on its inside is provided with a refractory lining of a variety of bricks or tiles made of a high-temperature ceramic. The thickness of the lining determines the temperature that the steel jacket feels during the process. If during operation radial nonuniform temperatures occur due to faults or damage in the refractory lining, the furnace shell may warp locally and change from the original circular shape (nominal shape) to an oval or irregularly bulged shape (local rotary kiln shape).

This leads to further disturbances for the refractory lining, which holds only due to their mechanical tension between the tiles or tiles. Here, the tiles or tiles can be loosened or put under an additional tension, so that one or more tiles or tiles fall or break and then fall off. In this case, the outer steel shell is no longer protected from the process heat and would melt at these locations if continued to operate. In such a case of damage, the rotary kiln would have to be stopped immediately, which would lead to a significant loss of production.

So far, such rotary furnaces are indeed cooled from the outside with air blowers, which are arranged on the outside of the rotary kiln over the entire length of the furnace shell. Such cooling fans are complex and occupy a large space around the rotary kiln. In addition, these blowers can neither detect nor individually cool strong local heating of the furnace shell and thus do not prevent faults and damage to the refractory lining.

It would therefore be desirable to have a system that can reliably avoid interference or damage in the refractory lining and that allows a longer operating time of the rotary kilns.

Summary of the invention

It is therefore an object of the invention to provide a system with which one can reliably avoid disturbances or damage in the refractory lining and which allows a longer service life of the rotary kilns.

This object is achieved by a cooling system for a rotary kiln rotating along a rotation axis for locally aligning a present rotary kiln mold with a desired shape, comprising an arrangement of one or more cooling modules for applying cooling liquid from outside onto the rotating kiln casing in an impact area in one the section corresponding to rotation about the furnace shell for local thermal deformation of the furnace shell in the impingement area, wherein the cooling module (s) are arranged spaced from the furnace shell and each comprise a controllable switching valve and a fan nozzle for emitting a pulsed fan-shaped cooling liquid jet, and wherein the cooling system at least one measuring unit with at least one fixedly arranged measuring sensor suitable for the continuous determination of distances in a predetermined direction between the measuring sensor and the rotating furnace shell in the circumferential section and the Bere tion of a location-dependent difference between the calculated from the specific distances existing rotary kiln shape and the desired shape, wherein a cooling system control based on the location-dependent difference, the switching valve for applying the cooling fluid so that by adjusting a pulse length and / or a pulse frequency of the cooling liquid jet the present rotary kiln shape is at least equalized in the impingement of the desired shape.

The term "equalize" refers to the change of the rotary kiln shape in the direction of the desired shape. Matching thus means that the difference between the present rotary kiln shape and the desired shape is reduced, not necessarily but that the present rotary kiln shape is already equal to the desired shape. The term "local approximation" refers to the fact that the cooling system can only cause deformation in the area of the cooling modules and the impact area. Thus, the deformations are limited to the impact area and thus only local. For the treatment of other sections of the furnace shell, the cooling system would have to be offset with the measuring sensor along the axis of rotation of the rotary kiln.

The impact area refers to the area in which the cooling liquid impinges on the furnace shell for cooling the furnace shell. The section of the furnace shell to be cooled is defined by the impact area and the rotary kiln rotating about its axis of rotation. As a result of the rotation, the area in which cooling water has been applied (impact area) runs around the furnace shell in the circumferential direction once every complete turn. This peripheral area thus forms the section of the furnace shell in which thermal deformations of the furnace shell can be produced with the cooling system according to the invention.

The measurement sensors used to measure the distance between the measurement sensor and the rotating furnace shell may be any suitable sensors. The vapor formed by evaporation of the cooling liquid on the furnace shell affects the distance measurement only slightly, since the temporal evolution of the steam can be controlled by the choice of the pulse frequency of the cooling liquid jet. Since the present rotary kiln shape is determined by the measured distances, it is first necessary to measure the distances between the measuring sensor and the kiln shell over at least one complete revolution of the kiln shell. For the calculation of the rotary kiln form, the measuring sensor must be mounted stationary, so that any specific changes in distance, which is concluded on a furnace shell deformation, not caused by spatial fluctuations of the measuring sensor. The person skilled in the art is able to mount the measuring sensor correspondingly solid and design stationary. With the stationary mounting of the measuring sensor and the direction is determined (predetermined), in which the distance to the furnace shell is measured with the measuring sensor. The furnace shell can have different local deformations along one revolution in different regions, so that the distance measurement can result in different differences in position compared to the target shape, so that the difference between the present rotary furnace shape and target shape along a revolution is location-dependent.

The cooling system is a system of cooling modules and a cooling system control, which is in addition to the measuring unit with the individual cooling modules via one or more data lines, preferably a data bus, connected 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, 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, but without the thermal deformation of the furnace shell in the impingement area is too strong. Too much cooling, for example, due to a continuous jet of cooling fluid would cause intolerable stresses and deformations in the material of the furnace shell and possibly warp or bend the furnace shell even further, so that the rotary kiln may become inoperative. Deformations of the furnace shell, 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 also have very negative consequences for the operation of the rotary kiln, as the furnace shell material in the areas where it is unprotected inside the process temperature is exposed in the oven, can even melt. The latter also leads to the destruction of the rotary kiln. The 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, the cooling liquid is continuously applied to the impact area, while in the time between the respective pulses no cooling liquid impinges on the furnace shell. Only the cooling liquid of the next pulse then hits the furnace shell again. Thus, on the one hand, the short-term local maximum thermal deformation can be set via the pulse length, while the time-averaged thermal deformation 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 and thus greatly deformed, so that the desired alignment of the rotary kiln shape to the desired shape at each point of the furnace shell individually and mechanically depending on the local temperatures and the furnace shell material adjustable voltages are controlled and controlled. As liquids, any liquids can be used, which reduce the surface temperature by means of impact and evaporation on a hot surface and thus can exert a thermal stress on the furnace shell material and sufficient have low viscosity, so that they can be sprayed through a nozzle. 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 desired shape is stored in the cooling system control for further control and can optionally be changed by the operator of the rotary kiln. The desired shape is in cylindrical furnaces ideally a cylindrical shape. By the cooling system according to the invention, the present rotary kiln shape can be kept at least in the sprayable by the coolant jet area of the furnace shell in the sol-shape or at least very close to the desired shape, so that critical deformations for the intended operating time are excluded or very unlikely.

To achieve a cooling effect by evaporation with the subsequent local thermal deformation, the cooling liquid must impinge as reproducibly as possible on the impact surface of 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 hits the furnace shell in an easily adjustable and reproducible manner. This reproducibility is advantageous insofar as with a spray only one low or moderate approximation of the local rotary kiln shape was achieved to the desired shape and the same point to enhance the thermal deformation after a revolution to be sprayed again. In one embodiment, the fan nozzles are aligned substantially perpendicular to the impact area 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.

With a linear thermal expansion coefficient α for iron of approximately 12 * 10 ^-6 K ^-1 , protrusions in the furnace shell can be recirculated down to the centimeter range in the direction of the desired shape. With a cooling of 100K induced by the cooling, a bulge of the rotary kiln could be reduced by 1.2 parts per thousand relative to the radius of the rotary kiln. With an exemplary diameter of 5m, this change corresponds to a return of a bulged material by 5mm. Buckling of rotary kilns larger than 1 cm should be avoided for safe operation.

The cooling system according to the invention thus makes it possible to reliably avoid faults or damage in the refractory lining, which in turn makes possible a longer service life of the rotary kilns.

In one embodiment, the measuring unit is configured to measure, at least periodically, the distance between the measuring sensor and the furnace shell at least for a number of measuring points on the furnace shell along the circumferential direction. A periodic measurement facilitates the evaluation and calculation of the rotary kiln shape, since the measuring points are distributed symmetrically along a circulation around the kiln shell.

In a further embodiment, the measuring sensor for this purpose comprises a transmitter unit for emitting a measuring signal and a receiver unit for Receiving the measured from the furnace shell measuring signal and the measuring unit determines from the transmitted and received measuring signals the distance, preferably the measuring signal is a light signal in the visible spectral range, a laser signal, an ultrasonic signal and / or a radar signal. When evaluating the transit time of the measurement signals or the corresponding phase shift, the measurement signal preferably strikes the surface of the furnace shell in the radial direction. When using the triangulation method, the measurement signal can hit the surface of the furnace shell at a different angle and be reflected from there again at the geometrically predetermined angle. For this purpose, the receiving unit would have to be arranged in a suitable position for receiving the reflected measuring signal. The above distance measuring units are fundamentally known to the person skilled in the art. Advantageous for the cooling system according to the invention would be measurement signals that are not or only slightly influenced by the resulting during spraying of the furnace shell steam. Therefore, radar signals and ultrasonic signals are preferably used.

In one embodiment, the number of measuring points is suitably selected in order to be able to calculate the present rotary kiln shape with sufficient accuracy from the measuring points and the associated measured distances. Preferably, the present rotary kiln shape is calculated from the distances associated with the measuring points by means of a method of least error squares. The measurement accuracy that can be achieved with conventional measuring units is in the range of 1 - 2 * 10 ^-3 relative to the distance. From the distance measurements, the present rotary kiln shape can then be calculated via, for example, the so-called method of least squares. With a diameter of the furnace shell of several meters and a distance of the measuring points on the furnace shell of at most 1 cm, the error in determining the present rotary kiln shape is in the range of 1 mm or smaller. With these values, for example, a sufficient accuracy of the measurement is ensured. Usual occurring during operation Projections (bulges) extend laterally over the furnace surface over several 10 cm. For a protrusion to be detected, it must have a protrusion height greater than the measurement error or fit error. Thus, protrusions with a height of, for example, 5 mm could be reliably detected and are still well below a critical height for rotary kilns of more than 1 cm.

In a further embodiment, a positive difference or a negative difference between the present rotary kiln shape and desired shape denotes a protrusion of the furnace shell to the outside or a recess of the furnace shell inwards and the cooling system control is provided to adjust the pulse length and / or the pulse frequency of the cooling liquid jet in that the corresponding cooling during passage of locations of the furnace mantle with small positive differences by the coolant jet is lower than in the passage of passages of the furnace mantle with large positive differences through the coolant jet, while no cooling liquid is applied to locations with negative difference. Due to the cooling effect of the coolant jet, protrusions due to the shrinkage process can be returned after cooling. In order to compensate for negative differences, on the other hand, thermal expansion in the material would have to be induced, which is not possible by way of a sprayed-on liquid. Instead, correspondingly strong heat sources would have to radiate to the points with negative differences. Such heat sources could be provided, for example, with infrared beam modules that could heat material to temperatures up to 900 ° C.

In one embodiment, the cooling system control is provided for short differences in the pulse length of the cooling liquid jet at the same pulse rate when passing the positions of the furnace shell with small positive differences through the cooling liquid jet and the passage of the body of the furnace shell with larger positive differences through the To set the coolant jet longer. Over the pulse length can be adjusted very precisely the cooling effect by the coolant jet. The pulse length is compared to the pulse rate and the easier to control variable for the spraying process.

In one embodiment, the fan nozzles are configured to produce a fan-shaped cooling liquid jet having a first opening angle of at least 40 ° along the rotational axis of the rotary kiln. As a result, a cooling module can spray a larger area of the furnace shell with cooling liquid, so that the number of cooling modules can be limited for a complete spraying of a designated section of the furnace shell and the cooling system thereby manages with a smaller number of components for a given size of the area to be treated , 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 coolant jet can be configured via the selection and adjustment of the fan nozzle in such a way that adjacent impact zones overlap slightly with a plurality of adjacent cooling modules, since in the outer regions of the impact regions, generally less liquid is applied per surface than in the central region the impact area 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, so still overlap the areas of 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. Such a cooling liquid jet fanned out in the plane of the longitudinal direction of the rotary kiln may, for example, have a smaller second opening angle in the direction perpendicular thereto (perpendicular to the rotational axis of the rotary kiln). In one embodiment, the fan nozzles a second opening angle in the direction of rotation of the furnace shell, which is at most 30 °, preferably between 10 ° and 15 °. This small second opening angle allows a very precise control of the cooling effect along the rotation of the rotary kiln, which indeed rotates past the cooling system.

In another embodiment, the cooling system includes a plurality of cooling modules disposed along the rotational axis of the rotary kiln, the cooling system controller being connected to the switching valves of the existing cooling modules and configured to convert the switching valves based on the calculated difference between the existing rotary kiln shape and the desired shape of different cooling modules independent of each other for setting individual pulse length and / or pulse frequency for each cooling module drives. As a result, not only can the cooling for the respective circumference of the furnace shell be position-dependent controlled in an impact area for a cooling module, but the thermal deformation can be adjusted by different cooling modules depending on the location of the respective different Auftreffbereiche to the rotary kiln conditions and needs. In the area of the fire lance, for example, other cooling capacities are required for producing a thermal deformation 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 a further embodiment, a distance between the adjacent cooling modules and a pressure of the cooling liquid for the cooling modules are adjusted so that the respective impact areas of the cooling liquids touch each other on the furnace shell for adjacent cooling modules, preferably without overlapping, and thus a common impact area define the furnace shell. This ensures that the thermally treated Area can be completely cooled with the lowest number of cooling modules.

In a further embodiment, the cooling system controller is configured to emit a warning signal as soon as at least the difference between the rotary kiln shape and the desired shape exceeds a threshold value at least in a region of the section. Thus, with critical deformation 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 value can also be stored and changed in the cooling system control. It is dependent on the particular application of the rotary kiln and the furnace shell material and the still to be accepted for deformation.

In one embodiment of the cooling system, the cooling modules and the corresponding impact areas of the coolant jets are arranged relative to one another such that the impact areas of adjacent cooling modules completely cool the furnace shell along its axis of rotation at least in the section to be cooled, each cooling module having at least one first heat sensor connected to a cooling system controller for measuring a cooling system first local temperature of the furnace shell in the direction of rotation of the furnace shell seen before the impingement of the cooling liquid and the transmission of the first local temperature to the cooling system control, and the cooling system control is adapted to the switching valve of each cooling module according to a difference between the respective first local temperature and a To control target temperature so that by adjusting the pulse length and / or pulse frequency of the cooling liquid jet after a revolution of the furnace shell, the body of the Oven mantle, at which one revolution before the first local temperature was measured, then having a first local temperature, which is closer to the target temperature than in the previous measurement, if in However, the difference between the first local temperatures of these two measurements but less than 30K, preferably less than 15K, is applied to the respective revolution of cooling liquid on the respective impact area.

The invention further 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.

• fortlaufendes Bestimmen von Abständen in vorbestimmter Richtung zwischen dem Messsensor und dem sich drehenden Ofenmantel in einem der Drehung entsprechend um den Ofenmantel umlaufenden Abschnitt sowie
• Berechnen einer ortsabhängigen Differenz zwischen der aus den umlaufend bestimmten Abständen berechneten vorliegenden Drehofenform und der Soll-Form mit der Messeinheit;
• Einstellen einer Pulslänge und/oder einer Pulsfrequenz des Kühlflüssigkeitsstrahls mittels einer Kühlsystemsteuerung auf Basis der berechneten ortsabhängigen Differenz; und
• Aufbringung der Kühlflüssigkeit mittels des eingestellten Kühlflüssigkeitsstrahls von außen auf den sich drehenden Ofenmantel in einem Auftreffbereich in dem umlaufenden Abschnitt zur lokalen thermischen Verformung des Ofenmantels im Auftreffbereich, bis die vorliegende Drehofenform zumindest in dem Auftreffbereich an die Soll-Form angeglichen ist.

The invention further relates to a method for locally aligning a present rotary kiln shape of a rotary kiln rotating along a rotation axis with a furnace shell to a desired shape with a cooling system according to the invention comprising an arrangement of one or more cooling modules arranged at a distance from the furnace shell, a measuring unit having a fixed location arranged measuring sensor and a cooling system control, wherein each cooling module comprises a controllable switching valve and a fan nozzle for emitting a pulsed fan-shaped cooling liquid jet, the method comprising the steps of:

• continuously determining distances in a predetermined direction between the measuring sensor and the rotating furnace shell in a section corresponding to the rotation around the furnace shell
• Calculating a location-dependent difference between the existing rotary kiln shape calculated from the circumferentially determined distances and the desired shape with the measuring unit;
• Setting a pulse length and / or a pulse frequency of the coolant liquid jet by means of a cooling system control on the basis of the calculated location-dependent difference; and
• Application of the cooling liquid by means of the adjusted cooling liquid jet from the outside to the rotating furnace shell in an impact area in the circulating section for local thermal deformation of the furnace shell in the impact area until the present rotary kiln shape is at least in the impact area aligned with the desired shape.

In one embodiment of the method, the cooling system control adjusts the pulse length and / or the pulse frequency of the cooling fluid jet such that the corresponding cooling during passage of locations of the furnace shell with small positive differences by the coolant jet is lower than passage of locations of the furnace shell with large positive differences through the coolant jet, while no cooling liquid is applied to locations with negative difference, wherein the positive difference between the present rotary kiln shape and target shape denotes a protrusion of the furnace shell to the outside, preferably at positive differences, the pulse length of the cooling liquid jet at the same pulse rate in the passage of Setting the furnace shell with small positive differences set by the cooling liquid jet short and the passage of the body of the furnace shell with larger positive differences through the Coolant jet set longer.

In another embodiment of the method, the cooling system includes a plurality of cooling modules disposed along the rotational axis of the rotary kiln, and the cooling system controller is suitably connected to the switching valves of the existing cooling modules to independently control the switching valves of different cooling modules based on the calculated difference between the present rotary kiln shape and the target shape for setting individual pulse length and / or pulse frequency for each cooling module.

Brief description of the illustrations

Fig.1:

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

Fig.2:

eine Ausführungsform des beabstandet zum Ofenmantel angeordneten erfindungsgemäßen Kühlsystems im seitlichen Schnitt;

Fig.3:

eine schematische Darstellung der vorliegenden Drehofenform und der Soll-Form im seitlichen Schnitt durch den Drehofen senkrecht zur Rotationsachse;

Fig.4:

eine andere Ausführungsform des beabstandet zum Ofenmantel angeordneten erfindungsgemäßen Kühlsystems in Draufsicht;

Fig.5:

eine Ausführungsform des erfindungsgemäßen Verfahrens zur lokalen Angleichung einer vorliegenden Drehofenform an eine Soll-Form.

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:

an embodiment of the spaced apart from the furnace shell cooling system according to the invention in a lateral section;

Figure 3:

a schematic representation of the present rotary kiln shape and the desired shape in the lateral section through the rotary kiln perpendicular to the axis of rotation;

Figure 4:

another embodiment of the spaced apart from the furnace shell cooling system according to the invention in plan view;

Figure 5:

an embodiment of the method according to the invention for the local alignment of a present rotary kiln mold to a desired shape.

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 tens of meters 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 61 to be processed, which is introduced into the rotary kiln 1 on the inlet opening 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 61 which require a high process temperature, the rotary kiln 1, as shown here, becomes direct, 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 exposed to these high temperatures have a furnace shell 2 of stainless steel or high temperature steel which can be exposed to temperatures between 250 ° C and 500 ° 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 or ceramic tiles 71, which are arranged side by side in contact with each other.

Fig.2 shows an embodiment of the distance to the furnace shell 2 arranged cooling system 3 according to the invention for a rotary axis R rotating DR rotary kiln 1 for local adjustment of a present rotary kiln form VF to a desired shape SF in the lateral section perpendicular to the axis of rotation of the rotary kiln. The cooling system 3 in this embodiment comprises a cooling module 31 for applying 130 cooling liquid 4 of FIG on the outside of the rotating furnace shell 2 in a local limited by the shape of the coolant jet impingement area 22 in a rotation corresponding to the furnace shell 2 rotating portion 21 for local thermal deformation of the furnace shell 2 in the impingement region 22. The cooling module 31 includes a controllable switching valve 311 and a fan nozzle 312, with which a pulsed fan-shaped cooling liquid jet 4 can be discharged in the direction of the furnace shell 2, if in the impingement region 22 a local thermal deformation of the furnace shell 2 is desired. In order to determine whether a local thermal deformation is to be carried out, the cooling system 3 comprises at least one measuring unit 35 with at least one stationary measuring sensor 36 suitable for the continuous determination of distances A in the direction predetermined by the alignment of the measuring sensor 36 on the furnace shell 2 Direction between the measuring sensor 36 and the rotating furnace shell 2 in the circumferential section 21. The measuring sensor 36 comprises a transmitter unit 361 for emitting a measurement signal MS and a receiver unit 362 for receiving the reflected from the furnace shell 2 measurement signal MS. The measuring unit 35 determines the distance A from the transmitted and received measuring signals MS. The measuring sensor 36 is preferably mounted at a distance of less than 1 m from the furnace shell. The measurement signal MS is, for example, a light signal in the visible spectral range, a laser signal, an ultrasound signal and / or a radar signal. In an ultrasonic measurement, the distance can be calculated, for example, over the duration of the signal. In the case of radar signals, the distance can be calculated, for example, from a phase shift between emitted and received measurement signal. In the case of a laser signal, the distance can be calculated, for example, by means of triangulation, where the transmission angle is predetermined and the reception angle of the measurement signal is measured. The measuring unit 35 therefore comprises, in addition to the measuring sensor 36, a data processing unit, not shown here, for calculating the distances from the measuring signals and for calculating a location-dependent difference D between the one calculated from the determined distances A. present rotary kiln form VF and the target shape SF. A cooling system controller 32 then controls on the basis of the location-dependent difference D, the switching valve 311 for applying 130 of the cooling liquid 4, so that by setting 120 a pulse length and / or a pulse frequency of the cooling liquid jet 4, the present rotary kiln form VF caused at least in the impact region 22 by means of the cooling effect thermal deformation of the desired shape SF is adjusted. In this case, the time offset between measuring point 23 and impact area 22 must be taken into account, since the same position 23 on the furnace shell 2 rotates first under the measuring signal MS and then through the cooling-liquid jet 4. The rotating through the coolant jet 4 to be treated position 23 on the furnace shell 2 defines the impingement region 22 on the furnace shell 2, which is suitably struck by suitable control of the switching valve 311 by the coolant jet 4 and thus thermally deformed. The fan nozzle 312 is configured to produce a fan-shaped cooling liquid jet 4 having a first opening angle (not shown) of at least 40 ° along the rotation axis R of the rotary kiln 2 and also having a second opening angle W2 in the rotational direction DR of the furnace shell 2 which is at most 30 °, preferably between 10 ° and 15 °. This narrow second opening angle is advantageous in order to be able to precisely achieve a local thermal deformation in the direction of rotation. The measuring unit 35, the cooling system controller 32 and the switching valve 311 are connected to each other via suitable data lines 33. The cooling liquid 4 is supplied to the switching valve 311 and the fan nozzle 312 through suitable cooling liquid lines in the cooling system 3. The cooling system 3 with only one cooling module 31 shown in this embodiment can also be designed accordingly with a plurality of cooling modules in other embodiments, wherein the plurality of cooling modules can preferably be arranged adjacent to one another along the rotation axis R of the rotary kiln 1. The cooling system controller 32, which is arranged separately from the measuring unit 35 in this embodiment, can, in a further embodiment, be implemented as an integrated measuring and measuring unit Cooling system control be executed.

Figure 3 shows a schematic representation of the calculated existing rotary kiln mold VF and the desired shape SF in the lateral section through the rotary kiln 1 and its rotary kiln shell 2 perpendicular to the rotation axis R. The measuring unit 35 is configured in this embodiment, periodically the distance A in the radial direction between the Measuring sensor 36 and the furnace shell 2 for a number of measuring points 23 on the furnace shell 2 with equal distances on the furnace shell 2 to each other along the circumferential direction DR to measure. The complete circulation defines the section 21 of the furnace shell 2 to be treated on the rotary kiln 2. Although the respective individual measuring point 23 is always measured in absolute coordinates by the measuring unit 35 (at least in the case of an existing rotary kiln shape equal to the desired shape), wherein the rotation DR of the furnace shell 2 causes the measuring points 23 to be distributed over the circumference of the furnace shell 2 in a circle over the circumference of the furnace shell 2, resulting in the rotary furnace form VS in this section 21 (corresponding to the sectional area at this point of the axis of rotation R perpendicular to the axis of rotation R) of the furnace shell 2 can be determined. In this case, the number of measuring points 23 is selected in order to be able to calculate the present rotary kiln shape VF with sufficient accuracy from the measuring points 23 and the associated measured distances A. Preferably, the present rotary kiln shape VF is obtained from the distances A associated with the measuring points 23 by means of a method the least squares error. The number of measuring points 23 over the circumference of the furnace shell 2 or the relative distance of adjacent measuring points 23 on the furnace shell 2 to each other can be determined by the number of emitted measuring signals MS per unit time in a periodic measurement, since the rotational frequency of the rotary kiln 1 is constant. Here, the calculated difference D is referred to as a positive difference DP or as a negative difference DN between existing rotary kiln shape VF and target shape SF, if a protrusion of the furnace shell 2 to the outside of the Rotary axis off or a recess of the furnace shell 2 inwards to the axis of rotation is present (see dashed arrows). The positive difference DP is highlighted in gray. The small negative difference DN is not highlighted in color here to distinguish. The cooling system controller 32 is provided to set the pulse length and / or the pulse frequency of the cooling liquid jet 4 120 so that the corresponding cooling during passage of locations of the furnace shell 2 with low positive differences DP by the cooling liquid jet 4 fails lower than during passage of locations of the furnace shell 2 with large positive differences DP through the cooling liquid jet 4 in order to be able to dose the thermal deformation correspondingly to the targeted thermal deformation for matching to the desired shape SF. Preferably, the cooling system controller 32 may be provided to set the pulse length of the cooling liquid jet 4 at the same pulse rate when passing through the locations of the furnace shell 2 with low positive differences DP by the coolant jet 4 at positive differences and the passage of the body of the furnace shell 2 with larger positive To set differences DP longer with the coolant jet (4). In contrast, no cooling liquid 4 is applied to locations with a negative difference DN, since a thermal shortening of the material due to the cooling would increase the negative difference. In order to be able to achieve an approximation to the desired shape even with negative differences, this range would have to be heated accordingly for a thermal expansion required there. This could be done via likewise controlled by the cooling system control heat sources. Suitable heat sources for this purpose would be, for example, a plurality of infrared radiators arranged adjacent to one another which, at least for stainless steel oven shells, can produce temperatures above 250 ° C. for local material expansion. These heat sources would be arranged appropriately spaced from the furnace shell analogous to the fan nozzle. Corresponding optics or shields could allow a beam guidance of the heat sources analogous to the beam guidance of the coolant.

Figure 4 shows another embodiment of the spaced from the furnace shell 2 arranged cooling system according to the invention in plan view. Here, the cooling system 3 comprises two cooling modules 31, 31 'juxtaposed along the rotation axis R of the rotary kiln 1, the cooling system controller 32 being connected to the switching valves 311 of the existing cooling modules 31, 31' and configured to control the switching valves 311 on the basis of FIG calculated difference D between present rotary kiln shape and the desired shape of various cooling modules 31, 31 'independently for setting 120 individual pulse length and / or pulse frequency for each cooling module 31, 31' drives. The distance A1 between the two adjacent cooling modules 31, 31 'and the pressure of the cooling liquid 4 for the cooling modules 31, 31' is adjusted so that the respective impact areas of the cooling liquids 4 on the furnace shell 2 for adjacent cooling modules 31, 31 'touch , preferably without overlapping, thereby defining a common impingement region 22 on the furnace shell 2. In addition, the cooling system controller 32 may be configured to emit a warning signal W as soon as at least the difference D between the rotary kiln mold VF and the target shape SF exceeds a threshold SW at least in a region of the section 21, preferably the warning signal W becomes a rotary kiln control electronically 11 transmitted. The possibility of sending a warning signal W to the rotary kiln control 11 is independent of the number of cooling modules 31, 31 'used and thus applies equally to the exemplary embodiment in FIG Fig.2 with only one cooling module 31. The in Figure 3 embodiment shown may be configured in other embodiments with three or more cooling modules, whereupon also the description of the Fig.2 - 4 apply equally mutatis mutandis.

Figure 5 shows an embodiment of the method according to the invention for the local alignment of a present rotary kiln mold VF to a desired shape SF. To the embodiments of the rotary kiln and the cooling module is on the Figures 1 - 4 directed. The method in this embodiment comprises the steps of continuously determining 100 of distances A in a predetermined direction between the measuring sensor 36 and the rotating furnace shell 2 in a section 21 rotating around the furnace shell 2 according to rotation and calculating a location-dependent difference D between them from the rotary kiln mold VF and the target shape SF calculated with circulatingly determined intervals with the measuring unit 35; setting 120 a pulse length and / or a pulse frequency of the cooling liquid jet 4 by means of a cooling system controller 32 based on the calculated location-dependent difference D; and applying 130 the cooling liquid 4 by means of the adjusted cooling liquid jet 4 from the outside to the rotating furnace shell 2 in an impingement region 41 in the circulating section 21 for local thermal deformation of the furnace shell 2 in the impingement region 22 until the present rotary furnace form VF at least in the impingement region 22 is aligned with the target shape SF (represented by the back arrow from "130" to "100"). Here, the cooling system controller 32 sets the pulse length and / or the pulse frequency of the cooling liquid jet 4 such that the corresponding cooling during passage of locations of the furnace shell 2 with small positive differences DP by the cooling liquid jet 4 fails less than passage of locations of the furnace shell 2 at large positive differences DP by the coolant jet 4, while no negative pressure fluid 4 is applied to negative-negative points DN. For this purpose, in a test step of the cooling system control, it is queried whether a present difference D is a positive difference DP (query D = DP). If the answer to this is "J", the cooling liquid 4 is applied to the furnace shell in steps 120 and 130. If the answer to this is "N", no cooling liquid 4 is applied. Preferably, in the case of positive differences DP, the pulse length of the cooling liquid jet 4 is set short at the same pulse frequency during passage through the locations of the furnace shell 2 with small positive differences DP through the coolant jet 4 and when the passages of the furnace shell 2 pass through the coolant jet 4 with larger positive differences DP set longer. If the cooling system 3 a plurality of cooling modules 31, 31 'arranged along the rotation axis R of the rotary kiln 1, the cooling system controller 32 is suitably connected to the switching valves 311 of the existing cooling modules 31, 31' in order to calculate, based on the calculated difference D between the present rotary kiln mold VF and the setpoint Form SF, the switching valves 311 different cooling modules 31, 31 'independently of each other for setting 120 individual pulse length and / or pulse frequency for each cooling module 31, 31' to control. In one embodiment, the cooling system controller 32 may be configured (shown in phantom) to emit a warning signal W as soon as at least the difference D between the rotary kiln mold VF and the target shape SF exceeds a threshold SW at least in a region of the section 21; Warning signal W electronically transmitted to a rotary kiln control 11. The query as to whether the difference D exceeds a threshold value SW can preferably be carried out before the query as to whether the difference D is a positive difference DP, since possibly too large negative differences DN could be critical for the operation of the rotary kiln.

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 SIGNS

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

21

circumferential section of the furnace shell

22

Impact area of the coolant on the furnace shell

23

Measuring points on the furnace shell, for which the distance to the measuring sensor is determined

3

Cooling system according to the invention

31, 31 '

cooling module

311

Switching valve in the cooling module

312

Fan nozzle in the cooling module

32

Cooling system control

33

Data lines in the cooling system

34

Coolant pipes in the cooling system

35

measuring unit

36

Measuring sensor (for sending a measuring signal)

361

Transmitter unit (for the measuring signal)

362

Receiver unit (for the measuring signal)

4

Coolant, coolant jet

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

100

continuous determination of the distances between the measuring sensor and the furnace shell

110

Calculate a location-dependent difference between rotary kiln shape and target shape

120

Setting the pulse length and pulse frequency of the coolant jet

130

Application of coolant to the furnace shell

A

Distance between the measuring sensor and the furnace shell

A1

Distance between adjacent cooling modules

D

Difference between rotary kiln shape (actual shape) and nominal shape

DP

positive difference between rotary kiln shape and target shape

DN

negative difference between rotary kiln shape and target shape

DR

Direction of rotation of the furnace shell, circumferential direction of the section 21

MS

measuring signal

R

Rotation axis of the furnace shell

SF

Target shape of the rotary kiln (furnace shell)

SW

Threshold for difference DF

VF

present rotary kiln form

W

Warning signal emitted by the cooling system

W1

first opening angle of the coolant jet

W2

second opening angle of the coolant jet

Claims (15)

A cooling system (3) for a rotary kiln (1) rotating along a rotation axis (R) for locally aligning a present rotary kiln mold (VF) with a desired shape (SF) comprising an arrangement of one or more cooling modules (31, 31 ') for applying (130) cooling liquid (4) from the outside onto the rotating furnace shell (2) in an impact area (22) in a section (21) rotating locally around the furnace shell (2) for local thermal deformation of the furnace shell (2 ) in the impact area (22), wherein the one or more cooling modules (31, 31 ') spaced from the furnace shell (2) are arranged and each comprise a controllable switching valve (311) and a fan nozzle (312) for emitting a pulsed fan-shaped cooling liquid jet (4) , and wherein the cooling system (3) at least one measuring unit (35) with at least one fixedly arranged measuring sensor (36) suitable for the continuous determination of distances (A) in a predetermined direction between Measuring sensor (36) and the rotating furnace shell (2) in the rotating portion (21) and for calculating a location-dependent difference (D) between the calculated from the determined distances (A) present rotary kiln mold (VF) and the desired shape (SF) wherein a cooling system controller (32) based on the location-dependent difference (D) controls the switching valve (311) for applying (130) the cooling liquid (4) such that by setting (120) a pulse length and / or a pulse frequency of the cooling liquid jet ( 4) the present rotary kiln mold (VF) is aligned at least in the impact area (22) of the desired shape (SF). The cooling system (3) according to claim 1,
characterized,
in that the measuring unit (35) is designed, at least periodically, to measure the distance (A) between the measuring sensor (36) and the furnace shell (2) at least for a number of measuring points (23) on the furnace shell (2). along the circumferential direction (DR). The cooling system (3) according to claim 2,
characterized,
in that the measuring sensor (36) comprises a transmitter unit (361) for emitting a measuring signal (MS) and a receiver unit (362) for receiving the measuring signal (MS) reflected by the furnace casing (2) and the measuring unit (35) from the transmitted and received signals Measurement signals (MS) determines the distance (A), preferably, the measurement signal (MS) is a light signal in the visible spectral range, a laser signal, an ultrasonic signal and / or a radar signal. The cooling system (3) according to claim 2 or 3,
characterized,
that the number of measurement points (23) is suitably selected, in order to calculate from the measurement points (23) and the associated measured distances (A), the present rotary kiln form (VF) with sufficient accuracy, preferably, the present rotary kiln form (VF) from the to the measuring points (23) associated distances (A) calculated by a method of least squares. The cooling system (3) according to one of the preceding claims,
characterized,
that a positive difference (DP) and a negative difference (DN) between the present rotary kiln form (VF) and desired form (SF) a protrusion of the furnace shell (2) outwards or a recess of the furnace shell (2) referred to the inside and the cooling system controller (32) is provided to set (120) the pulse length and / or the pulse frequency of the cooling liquid jet (4) so that the corresponding cooling during passage of locations of the furnace shell (2) with low positive differences (DP) by the cooling liquid jet (4 ) less than when passing through locations of the furnace mantle (2) with large positive differences (DP) through the coolant jet (4), while no coolant (4) is applied to negative difference sites (DN). The cooling system (3) according to claim 5,
characterized,
that the cooling system control (32) is provided to set the pulse length of the cooling liquid jet (4) at positive pulse differences (DP) at the same pulse frequency when passing through the positions of the furnace shell (2) with low positive differences (DP) by the cooling liquid jet (4) and during the passage of the positions of the furnace shell (2) with larger positive differences (DP) through the cooling liquid jet (4) to adjust longer. 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 (3) according to claim 7,
characterized,
in that the fan nozzles (312) additionally have a second opening angle (W2) in the direction of rotation (DR) of the furnace shell (2) which is at most 30 °, preferably between 10 ° and 15 °. The cooling system (3) according to any one of the preceding claims "
characterized,
that the cooling system (3) has several along the axis of rotation (R) of the Rotary kiln (1) arranged cooling modules (31, 31 ') and the cooling system control (32) is so connected to the switching valves (311) of the existing cooling modules (31, 31') and configured that they (32) the switching valves (311) based on the calculated difference (D) between the present rotary kiln shape and the desired shape of different cooling modules (31, 31 ') independently for setting (120) individual pulse length and / or pulse frequency for each cooling module (31, 31') drives. The cooling system (3) according to claim 9,
characterized,
that a distance (A1) between the adjacent cooling modules (31, 31 ') and a pressure of the cooling liquid (4) for the cooling modules (31, 31') are set so that the respective impingement of the cooling liquid (4) on the furnace shell (2) for adjacent cooling modules (31, 31 ') touch, preferably without overlapping, and define a common impact area (22). 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 (W) as soon as at least the difference (D) between the rotary kiln mold (VF) and the desired shape (SF) reaches a threshold value (at least in a region of the section (21)). SW), preferably the warning signal (W) is transmitted electronically to a rotary kiln control (11). A rotary kiln (1), preferably cement rotary kilns, with a cooling system (3) according to claim 1. A method for locally aligning a present rotary kiln mold (VF) of a rotary kiln (1) rotating along an axis of rotation (R) with a furnace shell (2) to a desired shape (SF) with a cooling system (3) Claim 1 comprising an arrangement of one or more cooling modules (31, 31 ') arranged at a distance from the furnace shell (2), a measuring unit (35) having a stationary measuring sensor (36) and a cooling system controller (32), each cooling module (31, 31 ') comprises a controllable switching valve (311) and a fan nozzle (312) for emitting a pulsed fan-shaped cooling liquid jet (4), comprising the steps - continuously determining (100) distances (A) in a predetermined direction between the measuring sensor (36) and the rotating furnace shell (2) in a rotation of the furnace shell (2) circumferential portion (21) and - calculating (110) a location-dependent difference (D) between the present rotary kiln shape (VF) calculated from the circumferentially determined distances and the desired shape (SF) with the measuring unit (35); - Setting (120) a pulse length and / or a pulse frequency of the cooling liquid jet (4) by means of a cooling system control (32) on the basis of the calculated location-dependent difference (D); and - Application (130) of the cooling liquid (4) by means of the adjusted cooling liquid jet (4) from the outside on the rotating furnace shell (2) in an impact area (41) in the peripheral portion (21) for local thermal deformation of the furnace shell (2) in Impact region (22) until the present rotary kiln mold (VF) is at least in the impingement region (22) aligned with the desired shape (SF). The method of claim 13, wherein the cooling system controller (32) sets (120) the pulse length and / or the pulse frequency of the cooling liquid jet (4) such that the corresponding cooling passes through locations of the furnace shell (2) with low positive differences (DP). through the coolant jet (4) is less than passage of locations of the furnace shell (2) at large positive differences (DP) by the Coolant jet (4), while no negative liquid (4) is applied to negative-negative points (DN), wherein the positive difference (DP) between existing rotary kiln mold (VF) and target shape (SF) a protrusion of the furnace shell (2) denoted outside, preferably at positive differences (DP), the pulse length of the cooling liquid jet (4) at the same pulse frequency during passage of the points of the furnace shell (2) with low positive differences (DP) by the cooling liquid jet (4) set short and the passage of the Set the oven shell (2) longer with larger positive differences (DP) through the coolant jet (4). The method of claim 13 or 14, wherein the cooling system (3) comprises a plurality of cooling modules (31, 31 ') arranged along the rotational axis (R) of the rotary kiln (1) and the cooling system controller (32) with the switching valves (311) of the existing cooling modules (31, 31 ') is suitably connected, based on the calculated difference (D) between the present rotary kiln mold (VF) and the desired shape (SF), the switching valves (311) of different cooling modules (31, 31') independently of each other for adjustment (120) individual pulse length and / or pulse frequency for each cooling module (31, 31 ') to control.

Images