Abstract:
In an industrial plant for producing or processing liquid, red-hot or hot metal a safety-relevant area is formed in the direct vicinity of the liquid or red-hot metal and the presence of a person is at least periodically not allowed. A detector unit is provided for the surveillance of the area, detecting electromagnetic radiation emitted by a present person or identifying the absence of electromagnetic radiation blocked by a present person. Furthermore, an evaluation unit is able to detect the presence of a person from the output data of the detector unit, and for a control unit which is connected to the evaluation unit. If a person is present in the safety-relevant area, the control unit automatically initiates an action acting against the presence of the person. By forming a plurality of safety-relevant areas having different danger levels, gentle stopping of the industrial plant is made possible.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Stage Application of International Application No. PCT/EP2007/056214 filed Jun. 21, 2007, which designates the United States of America, and claims priority to German Application No. 10 2006 032 955.4 filed Jul. 17, 2006, the contents of which are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to an industrial plant for producing or processing liquid, incandescent or hot metal, particularly a blast furnace installation or a rolling mill in which a safety-relevant area, in which the presence of a person is not permitted at least temporarily, is formed in the direct environment of the liquid or incandescent metal. 
       BACKGROUND 
       [0003]    Devices for the surveillance of spatial areas are known, e.g. from DE 101 63 534 A1, DE 102 21 578 A1 and DE 10 2004 047022 A1. In this context, sensors are used which provide three-dimensional information about the monitored area. The principle of the 3D CMOS sensor is thus based on the fact that a laser and an electronic lock are exactly synchronized. The lock opens exactly with the emission of the laser pulse. The extremely short light pulse illuminates an obstacle—if present—and the reflected light pulse impinges on the 3D CMOS image converter. The sensor registers the propagation times which are evaluated as a measure of the distance and the shape of the obstacle. A light-emitting diode or a laser can be used as transmitter. One pixel of the CMOS sensor can in each case comprise one photodiode and an associated pixel capacitor which is discharged by illumination of the photodiode when the time window is open. 
         [0004]    Modern industrial plants must be planned and operated in such a manner that the risk to persons is reduced to a minimum. As a rule, therefore, certain plant sections with high hazard potential are partitioned off or the access to some areas is blocked. For this purpose, protective grids and gates can be provided. 
         [0005]    For the partitioning or control of hazardous areas around machines or in simple industrial plants, so-called switching mats or also optical systems, e.g. light barriers are also known. Like fences with access gates, switching mats have high constructional complexity. Optical or radiation-based systems are not taken into consideration under extreme environmental conditions. 
       SUMMARY 
       [0006]    According to various embodiments, a safety-relevant area can be secured and checked in a constructionally simple manner in an industrial plant having a very strong heat emission, namely in an industrial plant for producing or processing liquid, incandescent or hot metal. 
         [0007]    According to an embodiment, an industrial plant for producing or processing liquid or incandescent metal, particularly a blast furnace installation or rolling mill in which a safety-relevant area, in which the presence of a person is not permitted at least temporarily, is formed in the direct environment of the liquid or incandescent metal, characterized by a surveillance device for the safety-relevant area, may comprise: a) a detector unit which detects electromagnetic radiation emanating from a present person or the absence of electromagnetic radiation blocked out by a present person, wherein the detector unit is based on a combination of at least two of the following detector types:—a motion detector,—a light barrier,—a video camera or a CCD camera,—a thermal camera,—a combination of light transmitter and semiconductor matrix sensor, particularly in CMOS technology, b) an evaluating unit which detects from output data of the detector unit the presence of a person, and c) a control unit connected to the evaluating unit, which, when a person is present in the safety-relevant area, automatically initiates an action acting against the presence of the person, and d) a plant control device which is connected to the control unit in such a manner that when an endangered person is detected, the plant control device can automatically carry out an intervention in the plant operation which reduces the hazard, particularly in real time. 
         [0008]    According to a further embodiment, the detector unit can be based on at least one and preferably on a combination of several of the following detector principles:—1-D sensor or line scan, particularly light barrier,—2-D sensor or area scan, particularly light curtain or 2D camera,—3-D sensor, particularly comprising a light transmitter, a semiconductor matrix sensor with one photodiode and one capacitor per pixel for integrating the reflected transmitter light and a delay determining unit. According to a further embodiment, the detector unit may generate an image from the safety-relevant area and the evaluating unit may carry out image processing. According to a further embodiment, the image processing may carry out object or pattern recognition, preferably on the basis of a neural network, so that a person can be distinguished from a non-human object. According to a further embodiment, there may be no protective grids or fences or there may be fewer protective grids or fences for securing the safety-relevant area than would be necessary for ensuring adequate or prescribed safety without surveillance device. According to a further embodiment, at least one further safety-relevant area may be formed which differs or differ in its/their risk potential from the first-mentioned safety-relevant area and the further safety-relevant area or areas can be monitored separately for the presence of a person by the surveillance device. According to a further embodiment, at least one of the safety-relevant areas may have a danger level of between “maximum hazard” and “no hazard”. According to a further embodiment, the intervention can be carried out with its intensity depending on the risk potential of the safety-relevant area in which the forbidden person has been detected. According to a further embodiment, the intervention, in the case of a rolling mill, may include a reduction of the rate of rolling or of throughput and/or a stopping of the mill train. According to a further embodiment, the intervention may include in the case of a steel mill or blast furnace a delay and/or an interruption of an opening of the furnace. According to a further embodiment, the industrial plant may comprise an input device for establishing a locking area by the operating personnel of a control room. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    An exemplary embodiment of an industrial plant will be explained in greater detail with reference to the drawing in the text which follows. 
           [0010]    The single FIGURE shows an embodiment of a continuous-casting plant with hot rolling mill in a greatly diagrammatic form. 
       
    
    
     DETAILED DESCRIPTION  
       [0011]    As mentioned above, according to various embodiments, a surveillance device for the safety-relevant area, may comprise:
       a detector unit which detects electromagnetic radiation emanating from a present person or the absence of electromagnetic radiation blocked out by a present person,   an evaluating unit which detects from output data of the detector unit the presence of a person, and   a control unit connected to the evaluating unit, which, when a person is present in the safety-relevant area, automatically initiates an action acting against the presence of the person.       
 
         [0015]    According to various embodiments, a radiation-based surveillance device can guarantee the required safety for a safety-relevant area also in industrial plants having a high heat and infrared radiation emission. The various embodiments are thus breaking with a technical prejudice. The experts have hitherto not considered such detector units for blast furnace installations or rolling mills. Instead, a great amount of effort is expended with mechanical access barriers now as before. The various embodiments have the advantage that elaborate mechanical latching devices such as innumerable electrically latched gates in a fence etc. are not necessary for guaranteeing adequate safeguarding of persons. Dispensing with or reducing the number of such protective grids and/or gates also has considerable advantages in the case of plant maintenance because these fences and gates do not then impede the access to the plant. 
         [0016]    The detector unit can be preferably based on at least one of the following detector types:
       a motion detector,   a light barrier,   a video camera or a CCD camera,   a thermal camera,   a combination of light transmitter and semiconductor matrix sensor, particularly in CMOS technology.       
 
         [0022]    The combination of at least two of the aforementioned detector types in the detector unit may be particularly preferred as a result of which a particularly high safety standard can be achieved. 
         [0023]    It can also be of special advantage if detector principles with different detection dimensionality are used in the detector unit such as, e.g. a one-dimensional sensor or a line scan, particularly a light barrier, and/or a two-dimensional sensor or an area scan, particularly a light curtain or a 2D camera, and/or a three-dimensional sensor, the latter comprising, in particular, a light sensor, a semiconductor matrix sensor with one photodiode per pixel and a capacitor for integrating the reflected transmitter light and a delay determining unit. 
         [0024]    According to a further embodiment, the detector unit is set up for generating an image from the safety-relevant area and the evaluating unit processes the image. In the image processing, an object or pattern recognition can preferably be carried out, preferably based on a neural network so that a person can be distinguished from a non-human object. 
         [0025]    Apart from the detection of a hazard to persons, this also makes it possible to detect other unplanned or irregular movements, e.g. by vehicles or falling parts, in the plant. 
         [0026]    According to a further development, at least one further safety-relevant area is formed in the industrial plant which differs or differ in its/their risk potential from the first-mentioned safety-relevant area wherein the further safety-relevant area or areas can be monitored separately for the presence of a person by the surveillance device. In this context, at least one of the safety-relevant areas preferably has a danger level of between “maximum hazard” and “no hazard”. 
         [0027]    According to another embodiment, the control unit is connected to a plant control device so that, when an endangered person is detected, the plant control device can automatically carry out an intervention in the plant operation which reduces the hazard, particularly in real time, online and/or without the interposition of human inputs. 
         [0028]    In this context, it is of quite particular advantage if the intervention can be carried out with its intensity depending on the risk potential of the safety-relevant area in which the forbidden person has been detected. This advantageously results in the possibility for a “gentle” stopping of the plant, e.g. by initially reducing the rate of rolling or throughput in a rolling mill when a person is detected in an area of medium risk potential and only reducing the rate of rolling or throughput to zero, i.e. stopping the plant, if the person penetrates the area of maximum risk potential. 
         [0029]    In a steel mill or a blast furnace, the response to a person penetrating can consist of a delay and/or a complete interruption of an opening of the furnace. 
         [0030]    The industrial plant also may preferably have an input device for establishing a locking area by the operating personnel of a control room. The operating personnel can thus flexibly define, for instance within an area of medium risk potential, a section, the so-called locking area which temporarily has a higher or the maximum risk level, for instance because a machine with increased risk potential is temporarily stored in this area. 
         [0031]    The single FIGURE shows as the industrial plant  1  a continuous-casting plant with hot rolling mill in a greatly diagrammatic form. The invention can also be applied in a cold rolling mill where the steel, e.g., is hotter than 100° C. 
         [0032]    Liquid metal  2 , e.g. iron, is conducted through a funnel mold  3  and deflection rollers from a vertical feed direction to a horizontal feed direction. In the horizontal, the ribbon  6 , which is still glowing, passes through several rolling stands  5  after it has been heated in an induction furnace  7 . 
         [0033]    Around the continuous-casting and rolling area of the industrial plant  1 , several safety-relevant areas B 1 , B 2 , B 3  are formed which are monitored in each case separately by themselves by a surveillance device. The monitoring has the aim of finding out which processes occur in the respective area B 1 , B 2 , B 3  and, in particular, whether a person has penetrated in forbidden manner in the respective area B 1 , B 2 , B 3 , who would be exposed to an unacceptable hazard in this area. The safety-relevant areas comprise a secure area B 3 , a less hazardous area B 2  and a very hazardous area B 1 . 
         [0034]    The surveillance device, particularly for the safety-relevant areas B 1  and B 2 , comprises a detector unit having a number of different detectors. These are a CCD camera or video camera  10  which generates a two-dimensional image (projection) of the area monitored, furthermore a three-dimensional image sensor having a combination  12  of a light transmitter and a semiconductor matrix sensor arranged in the immediate vicinity of the light transmitter, furthermore a motion detector  14  and a light barrier  16 A,  16 B. The motion detector  14  is based, for example, on the so-called pyroelectric effect. The light barrier can be operated with visible or invisible light. As the 3-D sensor, for example, a semiconductor matrix sensor in CMOS technology is used such as is described, for example, in DE 10 2004 047022 A1, DE 101 63 534 A1 or DE 102 21 578 A1. 
         [0035]    Due to the interaction of these different detector types and detector principles, an evaluating unit  22  which is supplied wirelessly or in wire-connected manner with the output data of the said detectors, can detect in a particularly reliable manner the presence of a person in the safety-relevant area B 1  or B 2  and distinguish him for example from artifacts generated from the continuous-casting or rolling area due to interference radiation. To further secure the person detection process, an object and pattern recognition of the image generated by the detector unit also takes place in the evaluating unit  22  by means of a neural network. 
         [0036]    The different safety-relevant areas B 1 , B 2  can be separately monitored as images in that there is a separate camera or a separate matrix detector for each area, i.e. that the different areas B 1 , B 2  are defined and specified by the respective acquisition cone of the associated detectors. As an alternative, the areas B 1 , B 2  can be monitored jointly by a common detector, preferably a 3-D sensor, wherein the distinction whether there is an unwanted person in the area B 1  or in the area B 2  can then be carried out as an evaluation by means of position data which are supplied by the detector. 
         [0037]    In a control unit  24  functionally following the evaluating unit  22 , for the case where an unwanted person is detected in a safety-endangered area B 1  or B 2 , an action acting against the presence of this person is initiated. This can consist in that the person is first warned, e.g. for a short time, by a light or tone signal, e.g. by means of a loudspeaker  26 . At a higher escalation level, the control unit  24  acts directly functionally on the plant control device  30  which, together with the evaluating unit  22  and the control unit  24 , is accommodated in a control room  20  of the industrial plant  1 . In the case where the person, after a short audible warning time, is still located in the hazardous area B 1  or B 2 , the mill train  5  is stopped or the rate of throughput, respectively, is reduced. This is done without requiring an intervention by the operating personnel. 
         [0038]    In the case where the safety-relevant areas B 1 , B 2  are monitored by a 3-D sensor, in particular, it is of special advantage that the operating personnel in the control room  20  can establish via an input device  40  a locking area V which is temporarily graded as having an increased risk potential. The locking area V shown can thus be temporarily graded in the risk potential of the area B 1 , for example, i.e. if a person enters the locking area V, an action of the highest escalation level is immediately triggered, e.g. the immediate stopping of the rolling mill. 
         [0039]    According to one variant, a thermal camera is used as camera, which results in the advantage that it is not only persons in unwanted areas which can be identified but also other unusual temperature variations can be detected in the industrial plant, for instance if liquid metal emerges at an unwanted location or hot iron parts have fallen down.