A device for estimating an outer surface temperature of a radiant coil which is provided in an cracking furnace for ethylene production including a convection coil that preheats hydrocarbons as raw materials and steam, a radiant coil that thermally decomposes the preheated hydrocarbons and steam, and a housing for accommodating them, and which includes an imaging camera that images a region to be imaged of the radiant coil, and an image analyzer that processes an output signal from the imaging camera and estimates an outer surface temperature of the radiant coil.

A method relates in particular to the repair of a refractory lining of a metallurgical vessel (10) in the hot state. This repair takes place here by means of an supplying apparatus (15). In addition, recording of at least the worn regions and monitoring of the repair are carried out by means of a device (20). Before, during and/or after the supplying of at least a partial region of the areas (13) of the refractory lining (12) of the vessel (10) to be repaired or the gunning jet (18) is recorded photographically here with visualisation of the temperature ranges (26, 27, 28), and this results in an evaluation with regard to different parameters such as properties, layer thickness and/or distribution of the supplied material. It has been demonstrated that by means of this visualisation of the temperature ranges of the areas to be repaired and of the refractory material during supplying different parameters can be established very accurately, and as a result optimal coating of the wall lining can be achieved.

A method for operating an extinguishing system comprisesan electronic controller (15) with a computer module (18) for data processing and a memory device (17), wherein the controller (15) comprises an image processing device which receives and evaluates data from a camera (8), at least one extinguishing agent dispenser (9) connected to the controller, which extinguishing agent dispenser is connected to an extinguishing agent line for supplying extinguishing agent andat least one camera (8) connected to the controller. The image processing device evaluates image regions that indicate a hotspot (6) with regard to isothermal regions (22), compares these regions (22) with stored patterns and, depending on the comparison, controls the extinguishing agent dispenser (9) to discharge extinguishing agent or prevents the discharge of extinguishing agent.