Patent Publication Number: US-6656414-B2

Title: Device for continuously measuring the temperature in pelletizing furnaces

Description:
DISCLOSURE OF THE INVENTION 
     The present invention is related to a device for continuously measuring the temperature in pelletizing furnaces and, more particularly, to a system for continuously measuring the temperature in pelletizing and sintering furnaces, which is resistant to the aggressive environment found in the grate cars used for pelletizing and/or sintering operations. 
     It is known that in pelletizing and sintering processes it is always important to check the pellet burning range, in order to optimize the consumption of fuel used therein, besides assuring a suitable product quality; furthermore, said verification is required for evaluating the effect of the process temperatures on the thermal treatment of the grate cars. 
     Conventionally, in order to measure the temperature in the pelletizing grate cars, the operators promote short stops along the course of the grate car in order to insert temperature detectors on the sides thereof, thus detecting timely and promptly the temperature of the pellets, as well as that of the grate car, at that time. 
     Besides the fact that the grate car stop approach for measuring the temperature has been widely used, it brings about a number of drawbacks, examples of which can be the fact that the grate car stop generates distortions in the thermal balance of the furnace and also causes a random distribution throughout the pellet layer. 
     When such distortions occur, the actual process burning temperature cannot be attained, what it makes it difficult to get the aimed results and masks the measurement values. 
     In order to minimize the inconveniences of the grate car stops, the use of meters, called travelers, was then adopted, which meters were launched with the product as the burning process went on. This attempt has not attained compensating results, for the meters were submitted to a risk of irreversible damage, thus requiring the frequent collection thereof for analysis. 
     Therefore, one of the objects of the present invention is to provide a device for continuously measuring the temperature in pelletizing furnaces that allows for a continuous measurement of the product while the grate car moves along the furnace, without the occurrence of damages to the meters or any interference in the pelletizing or sintering process. 
     Another object of the present invention is to provide a device for continuously measuring the temperature in pelletizing furnaces that allows for a continuous evaluation of the burning process temperature and its influence on the mechanical structures of the grate car that moves along the furnace, thus making it possible to optimize the fuel consumption and improving the product quality. 
     Another object of the present invention is to provide a device for continuously measuring the temperature in pelletizing furnaces that may have different temperature measuring sites in a single grate car, thus making it possible to analyze the pelletizing and/or sintering process temperature at different levels and sites of the product present on the grate car. 
     These and other objects and advantages of the present invention are attained by using a device for continuously measuring the temperature in pelletizing furnaces comprising the provision of a plurality of temperature detectors disposed at fixed sites on the grate cars, which detectors are however selectively and vertically displaceable in relation to the grate car support plan and follow the latter along the furnace in order to continuously and instantaneously inform the actual burning temperature of the product at that site and/or product layer depth being burned and at each stage of said process; wherein all the detectors are connected to a data collector which is encapsulated and also attached to the grate car and follow the latter as it moves through the interior of the furnace, each data collector being interconnected by tightening lines to said detectors and permanently monitored by measuring units that receive and determine through graphs the thermal profile of the process between two measuring sites selected. 
    
    
     The present invention will be described below with reference to the accompanying drawings, wherein: 
     FIG. 1 represents a perspective view of a grate car having its side partially cut for a better visualization of said top temperature detectors disposed along the sites on the car platform; 
     FIG. 2 represents a top view of a grate car provided with temperature detectors of the top type and the type that can be angularly displaced in relation to the grate car support plan; 
     FIG. 3 represents an expanded perspective detailed view of the top detector disposed between the grate car structure, before receiving the bars that make out the support plan; 
     FIG. 4 represents an expanded perspective detailed view of the case for encapsulating the data collectors to be attached to the grate car; 
     FIGS. 5,  6 ,  7  and  8  represent, schematically and respectively, the connecting end of the thermal detector rod and the data collector, and the angular locking mechanism thereof in relation to the side of the grate car, and the corresponding positioning of the end of the temperature detecting rod of said thermal detector in relation to the grate car support plan; and 
     FIG. 9 represents a graph generated by the measuring unit showing the temperature values that are continuously obtained between two sites of the burning process in the interior of the furnace. 
    
    
     In accordance with these illustrations, the device for continuously measuring the temperature in pelletizing furnaces object of the present invention is basically comprised of a plurality of temperature detectors  1  and  2  disposed at fixed sites of the grate car  10  that follow the latter along the furnace, not illustrated, in order to continuously and instantaneously inform, through data collectors and measuring units, also not illustrated, the actual burning temperature of the product at the detected site. 
     As mentioned above, all the temperature detectors  1 ,  2  are connected to a data collector that is embedded in a housing  20 , shown in FIG. 4, which also is attached to the grate car  10 , in order to follow the latter as it moves through the interior of the furnace. 
     The data collector inside the housing  20  is interconnected by means of the tightening lines  21  to said detectors  1  and  2 , by means of male couplers  22  and female  23  couplers, see FIGS. 4,  5  and  7 , in such a way that all detectors  1  and  2  provided in the grate car  10  can be permanently monitored by the measuring units that receive and analyze the data and issue thermal profile graphs of the burning process, as shown in FIG.  9 . 
     As can be seen in FIG. 3, one type of the temperatures detectors  1  to be attached to the grate car  10  is defined by a linear straight cylindrical rod mounted orthogonally in relation to the support plan  11  and fixed between the structures  12  of said support plan  11  by means of the longitudinal fastening fingers  3  that incorporate the triangular projections  4  coplanar to the end of said top temperature detector  1 . 
     This type of top detector  1  is designed to measure the temperature on the upper portion of the layer of pellets loaded on the grate car  10 , which can reach a depth of 400 mm, and by using said top detector  1  it is possible to measure the temperature of the pellet interface disposed between the backing layer of 100 mm and the raw pellet layer. 
     On the other hand, in FIGS. 2,  5 ,  6 ,  7  and  8 , the detector having an “L” shaped cylindrical rod  2  and horizontally mounted coplanar to the support plan  11  and attached to the latter by means of half-jackets  5  that fasten axially the sensing rod  2  to the structures  12  of said support plan  11  but allow for a rotational and selective displacement of this longitudinal portion of the “L” shaped rod in order to allow the transversal portion of said rod  2  to angularly pivot in relation to the support plan  11  of the grate car  10 , thus making it possible to define the height required for measuring the temperature of a pellet bed disposed on the grate car  10 . 
     The positioning of the detector having the “L” shaped rod is changed by a guiding and locking mechanism defined by a through hole  6  on the side of the grate car  10 , said through hole  6  being provided with a pair of collars  7  on each of its side ends into which a locking pin  8  is selectively fitted, thus retaining the end of the male coupler  22  of the detector rod  2  between same and the respective end of the through hole  6 , therefore positioning the opposing end of the measuring unit either horizontally, as seen in FIGS. 5 and 6, or vertically, as seen in FIGS. 7 and 8. 
     The housing  20  for conditioning and protecting the data collectors, illustrated in FIG. 4, is made from a refractory material and is preferably parallelepipedical shaped and provided with two front circular openings  24  that define inspection holes that make it possible to read the data collected, without the need to open the housing  20 . The latter is provided with bolts  25  that make it possible to attach same to the grate car  10 . Thus, the detectors  1  and the  2  and the data collectors inside the housings  20  are displaced together with the grate car  10  while it moves along the furnace. 
     Although a preferred constructive concept has been described and illustrated, it should be clarified that design changes are possible and attainable without departing from the scope of the present invention.