Patent Publication Number: US-2018045464-A1

Title: An apparatus for adjusting the heat exchange

Description:
The present invention relates to an apparatus for adjusting the heat exchange, especially, but not exclusively, for use in the ceramic industry. The use of heat exchangers inside kilns for ceramic products, such as tiles, bricks, porcelain, etc. is well known. 
     In particular, the known exchangers are usually located in the cooling sections of the kiln, where the temperature of ceramic articles must be lowered. 
     Heat exchangers are used to recover energy from kilns, for example in order to heat buildings or supply dryers or the like. 
     A critical aspect of the use of the known systems consists in the fact that their absorption of heat can negatively impact the morphology of the ceramic product, in particular the planarity of tiles and regularity of the shape of porcelain products. 
     In fact, a sudden absorption of heat, especially if it takes place in a non-uniform manner, can cause changes of shape in a product that is not yet fixed, which can compromise the quality of the final product. 
     The technical task at the basis of the present invention is therefore to propose an apparatus for adjusting the heat exchange which overcomes the drawbacks of the prior art. 
     This technical task is reached by an apparatus produced in accordance with claim  1 . 
    
    
     
       Further features and advantages of the present invention will appear more clearly from the approximate, and thus non-limiting, description of a preferred but non-exclusive embodiment of the adjusting apparatus of the invention, as illustrated in the appended drawings, in which: 
         FIG. 1  is a schematic longitudinal sectional representation of a roller kiln, in which the apparatus according to the invention is implemented; 
         FIG. 2  is a schematic cross-sectional representation of the kiln in  FIG. 1 ; and 
         FIG. 3  is an enlargement of the detail K in  FIG. 1 . 
     
    
    
     With reference to the aforesaid figures,  1  generically denotes the apparatus for adjusting the heat exchange, according to the invention. The proposed apparatus  1  is especially, but not solely, intended for use in the ceramic industry. 
     In detail, the apparatus  1  was conceived to work in functional cooperation with heat exchangers located inside kilns  3  for firing ceramic products, particularly in the cooling sections. 
     Ceramic kilns  3 , like the one shown by way of example in the figures, are used for the production of ceramic articles, such as tiles, bricks, ceramics, etc . . . 
     These kilns  3 , as also shown in  FIG. 1 , have an elongated configuration defined by walls closed around a conveyor  30  which supports and conveys the ceramic articles, for example by means of rollers. 
     The exchangers  2  for which the invention is intended can be located anywhere, for example below the vault and above the conveyor  30 , or else below the conveyor  30  or on the walls of the kiln  3  alongside the conveyor  30 , etc . . . 
     In practical terms, the exchangers  2  are located inside the walls of the kiln  3  in positions such as to enable the removal of the heat irradiated by the ceramic articles in transit on top of the aforesaid conveyor  30 . 
     In the illustrated example, a plurality of exchangers  2  is provided, located both above and below the conveyor  30 ; however, this is not a mandatory aspect, since, for example, all of the exchangers  2  could be provided only above or only below the conveyor  30 , etc . . . 
     In practical terms, the invention is not limited by the positioning of the exchangers  2 . 
     The invention is particularly intended for application in the first cooling section of the kilns  3 , where rapid cooling takes place. 
     In fact, it is precisely in that section that the exchangers  2  achieve the best effectiveness of use, since it is the section in which the temperature of ceramic products can decrease, based on the different applications, from 1200-1300° C. to 600-400° C. 
     In this temperature interval, a larger portion of the heat released by the products is emitted by irradiation and a smaller part transferred by convection. 
     Since the exchangers  2  in question are suitable for absorbing irradiated heat, it can be understood that the proposed apparatus  1  has its intended use in the aforesaid first cooling section. 
     The exchangers can comprise a plurality of tubes  2 , for example bent in a serpentine manner, each extending mainly transversely to the axis of the kiln  3 , or any other configuration suited to the purpose. 
     In the example represented in the appended figures, the heat exchange tubes define respective exchangers  2  having a generically planar shape or in any case a prismatic shape with a prevalently planar extent. 
     In the specific version represented in the appended drawings, the aforementioned tubes  2  are substantially parallel to the aforesaid conveyor  30  for advancing the ceramic products. 
     In this case, the exchanger  2  has a first side turned toward the surface of the conveyor  30 , to which it is substantially parallel, and an opposite side facing, for example, a wall of the kiln  3 . 
     The proposed apparatus  1  comprises first of all shielding means  10  intended to be arranged facing an exchanger  2  (or also a number of exchangers  2 ) or at least one portion of at least one exchanger  2 . 
     Preferably, the shielding means  10  are provided in the kiln  3  in interposition between the plane in which the conveyor  30  lies, and over which the ceramic articles pass, and the exchangers  2 . 
     The shielding means  10  of the invention are variable, in that they are provided with at least one screen  11  movable between a position of maximum covering C of the exchanger  2  and at least an exposure position, in which the heat exchanger  2  is left at least partially uncovered by the screen  11  (see  FIG. 3 ). 
     Preferably, the apparatus  1  comprises a plurality of movable screens  11  and, more preferably, a number of screens  11  for each exchanger  2 . 
     More precisely, the screens  11  can be arranged in a plurality of exposure positions, including one of maximum exposure E, in which they do not cover the exchanger  2  completely or at all. 
     Hereinafter, for the sake of convenience, a generic position that may be taken on by the screens  11  will be called “operating position”. 
     In different operating positions, each screen  11  covers the exchanger  2  by a predetermined extent, i.e. over a given surface. 
     In fact, given that, as shown in  FIGS. 1 and 2 , the shielding means  10  are arranged between the plane of the conveyor  30  and the exchangers  2 , they are able to completely or partly “block off” the heat irradiated by the ceramic products toward the exchangers  2 . 
     Therefore, each operating position of the screens  11  can be characterized by the extent of the area of the exchanger  2  covered by it, taking the plane of the conveyor  30  as a reference or “point of view”. 
     Each screen is preferably planar in shape and can comprise or consist of a rigid plate-like flap  11 , for example made of insulating material. 
     Such flap  11  can have a quadrangular perimeter, preferably rectangular. 
     In particular, each flap  11  can be arranged with its length transversal to the longitudinal direction of extension of the kiln  3  and, as a consequence, of the conveyor  30 . 
     In the preferred embodiment, each screen  11  is rotatable about a respective axis of rotation A, so as to be able to be arranged in its various operating positions. 
     Therefore, each operating position is an angular position of the screen  11 , which corresponds to a degree of coverage of the exchanger  2  and, therefore, the extent of the covered area. 
     In this case, based on the inclination of a given screen  11 , and thus based on the specific operating position, one obtains a different absorption of heat by the portion of the exchanger  2  associated with that screen  11 . 
     This aspect will be discussed further in the explanation of the operation of the invention. 
     Every screen  11  can have a rotatably constrained edge, through which the axis of rotation A passes, and an opposite free edge; in addition it can have a longitudinal extent parallel to the axis of rotation A and perpendicular, therefore, to the direction of conveyance of the ceramic articles along the conveyor  30 . 
     Preferably, when the screens  11  move from the position of maximum covering C towards an exposure position, they are moved in an opposite direction relative to the exchanger  2 , i.e. toward the plane of the conveyor  30 . 
     In even more detail, according to a preferential aspect, each screen  11  has an extent that is equal to or greater than the width of the associated exchanger  2 . 
     In fact, if the exchangers  2  are arranged with their length in the direction of longitudinal extension of the conveyor  30 , they will have a width that is transverse to that direction; therefore, if the screens  11  are hinged on axes transverse to the longitudinal direction of the conveyor  30  (and of the kiln  3 ), to ensure the effective and complete lateral covering of the exchangers  2 , the screens  11  will usefully be fairly long (or wide, based on the orientation) so as to cover the cross section of the associated exchanger  2 . 
     The coverage (and exposure) of the exchangers  2  in the direction of their length effected, and above all adjusted, by setting the screens  11  into rotation, something that will be returned to during the explanation of the operation of the invention. 
     If the exchangers  2  and the plane of the conveyor  30  are parallel, in its position of maximum exposure E, every screen  11  can be arranged perpendicular to that plane and, in the position of maximum covering C (or minimum exposure), it can be parallel to the same plane. 
     Preferably, the screens  11  intended to adjust the coverage of a same exchanger  2  (or at least a portion thereof) are mutually arranged in such a way that, in the respective positions of maximum covering C, they will completely cover the aforesaid portion of the exchanger  2 . 
     In particular, in their position of maximum covering C, the screens  11  associated with a same exchanger  2  can be parallel to one another and, preferably, substantially coplanar, so as to define a substantially continuous covering wall, except for possible small slits between one screen  11  and another which do not appreciably impact the functionality of the apparatus  1  of the invention. 
     In this case, the covering wall is parallel to the plane of the conveyor  30 . In the preferred embodiment, in which the screens  11  are rotatable, those associated with a same conveyor  30  preferably have coplanar axes and are arranged at a mutual distance substantially equal to the distance between the aforesaid constrained edge and the opposite free edge. 
     If the screens  11  extend with their length in the direction of the axis of rotation A, the distance identified in the preceding paragraph is the width of the screen  11  itself. 
     Optional and non-mandatory constructive aspects of the shielding means  10  are described below. 
     The shielding means  10  can comprise, at least for each exchanger  2 , a support structure  4  provided for attaching the screens  11 , and which can be passed through by the tubes of the exchanger  2 . 
     In detail, this structure  4  can comprise one or more support elements  41 , for example plate-like elements preferably set vertically, provided with through holes for the passage of one or more rows of tubes  2  of the exchanger (see  FIG. 3 ). 
     In practical terms, the support elements  41 , besides supporting the screens  11  (and optionally further components described below) can also act like templates  11  for positioning the tube bundles of the exchanger  2 . 
     In the case represented in the figures, the tubes  2  are set in two horizontal rows at a predetermined mutual distance, the tubes of one row being staggered relative to those of the other row for reasons of efficiency of absorption that are not pertinent to the present description. 
     As partly alluded to above, the flaps  11  of the screens are revolutely coupled to the support structure  4 , for example by hinge pins  12  fixed at one of the sides of the individual flap  11 , for example one of the larger sides, in the case of a parallelepiped shape. 
     Even more in detail, in each of the aforementioned support elements  41  there can be fashioned a guide and coupling aperture  42 , which originates from a lower edge of the element itself and defines an indentation of an arched shape, which in turn defines the guide for inserting the pin  12 . 
     The aperture  42  ends in a seat for the pin  12  to rest in, for example U shaped. 
     The pins  11  and the aforesaid templates  11  can be made of 253 MA, stainless steel, or so-called “black steel” or another material with high heat resistance. 
     The proposed apparatus  1  can comprise activating means  5 , for example of a motorized type, able to automatically move the screens  11 . 
     In detail, the activating means  5  can be capable of individually activating the screens  11  or else can activate a plurality thereof simultaneously. 
     In both cases, the activating means  5  are intended to perform an adjustment in moving of the screens  11  in multiple operating positions. 
     The activating means  5  can comprise servo-controls, for example mounted at the templates  11 , or more complex kinematic systems. 
     For example, the aforementioned pins  12  can protrude externally of the templates  11  with a prismatic section suitable for mechanical coupling with the servo-controls  5 . 
     If use is made of kinematic systems based on levers or chains, a number of pins  12  can be constrained to the same transmission gears, so that the associated flaps  11  can be activated together. 
     Furthermore, the apparatus  1  of the invention can include a processing unit, such as a computer or a PLC or the like, configured to control the activating means  5  so as to adjust the exposure of the heat exchanger  2 , according to a predefined program, which is comprised and runs in the unit itself. 
     The operation of the invention is described below. 
     Based on the type of ceramic article produced in the kiln  3  and based on the specific cooling section in which the invention is implemented, and also based on further parameters tied to technological processes in the industry, the desired degree of heat absorption must be provided within a given section of the kiln  3 . 
     Given that, as explained above, the irradiation of heat from the tiles toward the exchangers  2  is reduced by the position of the screens  11 , the apparatus  1  of the invention enables the different screens  11  to be arranged in such a way as to obtain the desired level of heat absorption. 
     In order to obtain this, the screens  11  of a given exchanger  2 , or a part of these screens  11  placed opposite a certain portion of the exchanger  2 , are activated in rotation by the servo-controls, or other activating means  5 , so as to place them in the angular position corresponding to the desired absorption. 
     In this manner, therefore, one avoids both an over-absorption which could create morphological defects in the ceramic article, particularly in the planarity of tiles, and an under-absorption, which would decrease the effectiveness in the use of the exchangers  2  and would make the cooling process longer. 
     In summary, based on the aforesaid technological production requirements, the flaps  11  are arranged in a respective operating position which is comprised between the maximum covering one C, in which there is minimal heat absorption, ideally none, and the one of maximum absorption, in which the efficiency of the exchanger  2  is exploited 100%. 
     Various flaps  11  of the same apparatus  1 , which may even be associated with the same exchanger  2 , will thus be located in different angular positions, positions that can be changed over time as desired based on the changed technological and production requirements, with an extreme level of versatility and adaptability of the invention. 
     One example of application is that of exploiting the aforesaid processing unit not only to control and adjust the positions of the screens  11 , but also for an initial learning phase, in which the program for adjusting the screens  11  is obtained through a series of experiments serving to identify the characteristic parameters of the specific kiln  3  and the specific exchangers  2  with which the invention functionally cooperates.