Method and apparatus for detecting water leaks in metallurgical melting furnaces - Patents.com

Abstract

The present invention relates to a method for detecting water leaks in a metallurgical melting furnace. The present invention also relates to an apparatus for carrying out the method. Water leaks in the cooling or water pipes of the furnace vessel are detected by combining and correlating with each other the time-resolved measurement of exhaust gas characteristic values, such as the amount of water at the exhaust gas outlet, and the regulated pressure fluctuations of the cooling circuit, i.e. the pressure changes. In the event of a leak, the water pressure changes lead to a change in the amount of water flowing into the furnace vessel, which is time-correlated with the pressure changes of the cooling circuit. By determining the correlation of these signals, an evaluation device can determine a relationship based on the water leak.

Description

[Technical field]

[0001] The present invention relates to a method for detecting water leaks in a metallurgical melting furnace having a furnace vessel whose walls consist at least in part of water tube walls through which cooling water flows, as well as to an apparatus suitable for carrying out said method. [Background technology]

[0002] In metallurgical melting furnaces, for example electric arc furnaces, metals are melted and then cast. For this purpose, particularly high temperatures are required inside such metallurgical melting furnaces, so that the materials in the furnace vessel must withstand temperatures of up to 3500° C. Such temperatures pose special challenges for the equipment used.

[0003] Therefore, the individual components of the metallurgical melting furnace, which are in contact with the liquid metal and the hot exhaust gases, are made from refractory materials or from water-cooled components. Some parts of the metallurgical melting furnace, in particular the furnace vessel, are at least partially made of water tube walls through which water tubes pass during operation, which reduces the risk of damage or destruction of the walls of the furnace vessel by the molten metal and the hot exhaust gases.

[0004] One such metallurgical melting furnace with water tube walls is described in EP 2 601 469 B1. The water tube walls are made in the form of fluid-cooled plates or panels and are particularly suitable for use in metallurgical furnaces, in particular in electric arc furnaces for steel production. However, there is a frequent problem that strong thermal loads acting on the water tube walls, especially due to large temperature differences, lead to leaks in the water tube walls. As a result, water flows into the metallurgical melting furnace.

[0005] In principle, water is also generated in metallurgical melting furnaces by the combustion process inside the furnace vessel, for example by the combustion of added natural gas or hydrogen. In addition, at the beginning of the melting cycle, water is introduced by the metallic elements inserted in the furnace vessel. Further moisture comes from the vertically fixed graphite electrodes, where water flows down into the furnace vessel for cooling. The water present in the furnace vessel evaporates and is discharged via the exhaust system. However, even in the case of leaks, the majority of the water present in the exhaust gas comes from the abovementioned sources.

[0006] The problem with water penetrating additionally into the furnace vessel via water leaks is that it penetrates in a variably and locally manner, so that the penetrating water can accumulate at certain points. This happens because the metal parts to be melted, e.g. scrap, are usually irregularly structured and may have numerous pocket-like cavities in which the water at least partially remains and thus does not evaporate completely. This water, which accumulates in liquid form at certain points, can turn into large and ever-growing bubbles over time. If, during the further melting cycle of the scrap metal, due to the ongoing heating, very hot liquid metal comes into contact with such bubbles, there is a risk of explosive evaporation. As a result, serious damage to the metallurgical melting furnace or even its destruction can occur. Furthermore, the metal chunks that flow out of the metallurgical melting furnace (and possibly even splash around) represent a great danger to workers in the vicinity of the metallurgical melting furnace.

[0007] There are various methods for detecting such water leaks, which have hitherto been based on a relatively long-term furnace balance. DE 10 2009 051 931 A1, for example, describes a method for early detection of leaks in cooling devices for cooling industrial plants, in particular continuous casting plants. In this case, a controllable inlet valve and a controllable outlet valve are operated remotely and the deviation from the expected pressure is determined. In this case, the pressure profile can also be examined for changes over time. However, due to high process noise, such considerations cannot be used as a reliable indicator, since the dispersion effects of the entire process, in particular the input into the melting furnace, the evaporation during the process and the discharge through the exhaust gas channel, are too variable and depend on many requirements. The process noise here is the influence of process parameters, such as the influence of the flow rate, pressure, temperature or water content, caused by stochastic fluctuations and cross effects. In this case, it should be taken into account that individual parameters in complex process procedures cannot be measured in isolation, since they are mostly influenced by other occurring events. For example, water entering the exhaust gas comes from various sources that cannot be clearly identified when and where and the measured signals overlap. For example, the on / off of burners as well as the natural evaporation of water in the charged scrap usually lead to sudden increases or transitions in the moisture content in the exhaust gas.

[0008] In contrast, the ingress of water through leaks is a slow-starting, monotonous process that results in the ingress of relatively small amounts of water. The water ingressed through leaks results in a constant background of water vapor in the exhaust gases exiting through the exhaust gas outlet, which makes it difficult or impossible to clearly detect the water leak using state-of-the-art methods. This background signal of water ingressed through leaks grows only very slowly, sometimes taking several weeks. In order to be able to reliably detect such a water content, very accurate mass and furnace balances are required. Even the use of neural networks to evaluate the signal progression has proved to be very difficult so far, since such networks are too dangerous to train on a real furnace.

[0009] Balancing the water circulation system, by checking how much water flows into and out of the water cooling system per unit of time, also does not give reliable results. For example, 3 m per hour 3 A water leak that would cause water to leak into the reactor vessel would result in a total flow rate of approximately 900 m3 per hour. 3 The amount of water leaking is too small to be reliably detected at the time of the leak. Furthermore, leaks can occur at many other places, even outside the furnace. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] EP2601469B1 [Patent Document 2] DE102009051931A1 Summary of the Invention [Problem to be solved by the invention]

[0011] The invention is therefore based on the object of providing a simple and cost-effective method for reliably detecting water leaks in metallurgical melting furnaces, despite high process noise. [Means for solving the problem]

[0012] This problem is solved by a method and an arrangement with the features of the independent claims 1 and 8. Further developments are given in the dependent claims.

[0013] In particular, the object is achieved by a method for detecting a water leak in a metallurgical melting furnace, the method being carried out by means of a metallurgical melting furnace, an exhaust gas measuring device for measuring at least one exhaust gas characteristic value, a pressure regulator and an evaluation device.

[0014] In this case, the metallurgical melting furnace comprises a furnace vessel, a lid and an exhaust gas outlet, the wall of the furnace vessel being at least partially made up of a water tube wall through which cooling water flows.

[0015] The exhaust gas measuring device is arranged downstream of the exhaust gas outlet in the exhaust gas flow direction and is connected with the evaluation device in data technology. Depending on the exact arrangement of the exhaust gas device, the detected leaks are determined in different regions. According to an advantageous variant, the exhaust gas measuring device is arranged immediately after the exhaust gas outlet, which advantageously avoids the contribution of further water sources. A further advantage of such an arrangement is that leaks that occur only after the reactor vessel, i.e. in the exhaust gas line, do not contribute. Since leaks in the water tube wall of the reactor vessel in particular have a higher hazard potential, it is advantageous if it is clear whether it is really a leak in the reactor vessel. In contrast, leaks in the exhaust gas flow path are insignificant in terms of their hazard potential.

[0016] Furthermore, the evaluation device is also connected in data-technical terms to a pressure regulator, which can regulate and adjust the pressure of the cooling water in the water tube wall.

[0017] In this case, the method comprises the steps of: a) applying pressure variations to the cooling water using a pressure regulator, where the pressure variations are a sequence of temporary pressure deviations from a mean pressure; b) measuring the progression of exhaust gas characteristic values ​​using an exhaust gas measuring device, i.e. determining the measured values ​​over time; c) determining by means of an evaluation device the correlation between the course of the pressure fluctuations of the cooling water and the course of the exhaust gas characteristic values; for this purpose a correlation function is used; d) outputting said correlation by an evaluation device.

[0018] The results of said correlation can be processed in the evaluation device after each evaluation cycle so that a signal is output only if certain preconditions occur, or the correlation is output after each evaluation cycle.

[0019] In the sense of the present invention, cooling water refers to a fluid suitable for use in cooling equipment to cool technical equipment, which can in particular be water, while the method according to the invention can also be carried out with other fluids, in particular with other cooling liquids.

[0020] Preferably, the evaluation device provides an output signal, for example a warning signal, when the predetermined criterion is present.

[0021] Preferably, in order to determine the correlation according to step c), the course of the pressure fluctuations is transferred to an evaluation device or input into an evaluation device. Furthermore, the results of the measurement according to step b) are transferred to the evaluation device.

[0022] A progression of a parameter is, in the sense of the present invention, a sequence of successively determined values ​​of this parameter, i.e. the evolution of this parameter over time is shown.

[0023] Imposing pressure fluctuations on the cooling water in the sense of the present invention means the generation of pressure fluctuations, in particular the generation of sequences of defined temporary pressure deviations, i.e. sequences of defined temporary increases and / or decreases of the pressure of the cooling water, in particular the nominal pressure, which pressure can deviate upwards and / or downwards from the mean pressure, said pressure being the pressure of the cooling water or coolant in the cooling water pipes of the water pipe wall.

[0024] That is, pressure fluctuations in the sense of the present invention refer to a sequence of temporary pressure deviations from a mean pressure, where a number of successive pressure deviations follow a certain predefined pattern.

[0025] In this case, such pressure deviations have a certain duration and a certain deviation value, i.e. amplitude and deviation direction. In this sense, the deviation value refers to the degree of deviation from the mean pressure, where the deviation can be positive or negative. Furthermore, the pressure deviations can also have a certain time interval from each other.

[0026] In the event of a leak, an increase or decrease in the cooling water pressure leads to an increase or decrease in the amount of cooling water that penetrates into the furnace due to the leak, i.e. the amount of leakage. As a result, an image of the pattern of the defined pressure fluctuations applied to the cooling water, i.e. the image of the sequence of defined pressure deviations, also occurs in the exhaust gas in the form of a change in at least one exhaust gas characteristic value, for example the water concentration. This change in the exhaust gas characteristic value occurs in accordance with the defined pressure fluctuations. Via the correlation between the defined pressure fluctuations in the cooling water and the value changes of the exhaust gas characteristic value, it is possible to determine whether a leak is present in the cooling system.

[0027] Preferably, in order to obtain a sequence of pressure variations, i.e. pressure deviations, which can be well used for correlation, at least one pressure deviation parameter selected from the period, the deviation value and the interval is adapted from one pressure deviation to the next. Thus, in the sequence of pressure deviations, i.e. pressure deviations, the period and / or the deviation value and / or the interval of the pressure deviations are varied.

[0028] In this case, in the sequence of pressure fluctuations, only one pressure deviation parameter, for example only the deviation value of the pressure deviation or only the duration, or at least two of the pressure deviation parameters, for example the duration and the deviation value, can be changed. In this case, a characteristic pattern is generated that is determined by correlation in at least one of the exhaust gas characteristic values. Since the lines also cause pressure losses, the duration, also called the duration, is one of the important criteria for correlation and evaluation.

[0029] According to one advantageous design, the sequence of pressure deviation parameters is determined by a random generator (which may also be called a random number generator), by using which an irregular sequence of pressure deviations, i.e. also irregular pressure variations, can be realized, whereby the sequence of pressure deviations is determined by values ​​generated by the random generator between a minimum and a maximum pressure deviation parameter, for example between a minimum and a maximum duration.

[0030] For this purpose, a certain minimum unit can be defined, such that for example 3, 5, 8 or 10 values ​​are randomly selected for the pressure deviation parameter, a deterministic random generator can be used here.

[0031] Alternatively, a non-deterministic or hybrid random generator can be used.

[0032] In this way, it is possible to avoid or at least greatly reduce the likelihood of a coincidence of irregular changes in one of the exhaust gas characteristic values ​​with other effects, as frequently occurs, for example, in the case of periodic pressure fluctuations.

[0033] For example, the program can be used to generate a sequence of pulses for one second with varying deviation values. The number of pulses with the same deviation value is determined by a randomly generated number between the minimum and maximum durations, while the deviation value itself is determined by a randomly generated number between the minimum and maximum deviation values. Additional variations in amplitude up to a maximum value are possible.

[0034] The pressure fluctuations can, according to one possible design, be generated continuously, in which case, advantageously, leaks can be detected at any time.

[0035] Optionally, a certain time, for example 1800 seconds, is provided, which is then used for the correlation. In particular, the pattern does not repeat after said time, but a new pattern is generated, with which further correlations are then performed. Thus, in a two-step procedure, the correctness of a positive result can advantageously be verified. This increases the reliability of the method.

[0036] The exhaust gas characteristic values ​​are exhaust gas parameters, for example the proportion or amount of water contained in the exhaust gas, or the exhaust gas pressure or the exhaust gas temperature. A characteristic pattern based on the pressure application can be advantageously read out in different parameters or process values. The different exhaust gas characteristic values ​​can therefore be advantageously used for correlation measurements and can serve as more reliable indicators for leaks.

[0037] In the sense of the present invention, correlation is understood to mean the relationship between two signal sequences, i.e., here, the relationship between the time course of exhaust gas characteristic values ​​and pressure fluctuations. If the relationship between these courses is recognizable, and thus exists, this can be read into the correlation. Depending on the result of the correlation, it can be determined whether a leak exists or not, if certain values ​​and limits are determined depending on the selected evaluation method and correlation function. Since this is a statistical process, the limits can be selected depending on the desired and required probability of a correct or incorrect warning signal.

[0038] One advantage of the method is that the signal can be seen even in the presence of other possibilities for water being introduced into the reactor vessel: even in the case of very large fluctuations in the water amount due to other processes, small correlated fluctuations in the water amount seen at the exhaust gas outlet due to a leak can be reliably detected.

[0039] The amount of water introduced into the furnace process by other sources, especially in combination with its time uncertainty, makes the signal to be detected very small, but can still be successfully evaluated by the method according to the invention. Advantageously, the correlation between the pressure fluctuations of the cooling water in the water tube walls and the measurement of the amount of water in the exhaust gas is used to more reliably and successfully detect leaks in the water tube walls of the furnace vessel.

[0040] It should be noted here that even if a portion of the water that is introduced into the furnace vessel by a leak collects in liquid form, this water will always evaporate. The method according to the invention is based on the fact that the evaporated portion of the water that flows out through the exhaust gas outlet influences the signal of the exhaust gas measuring device.

[0041] According to one advantageous design of the method, inside the water tube wall, cooling water flows through at least two different sections, to which different pressure fluctuations are applied according to step a), the correlation according to step c) being carried out for each section, the pressure fluctuations being able to vary, for example, in frequency and / or amplitude and / or deviation.

[0042] In this case, according to one advantageous variant, each section is provided with an auxiliary line connected to it. The different sections preferably form different cooling circuits. In the different cooling circuits, different pressure progression patterns can be applied to each circuit. This can occur in the circuits with a time lag, i.e. successively in time, or even simultaneously. If the patterns are different, a circuit having a leak is detected by a corresponding correlation. Depending on the characteristics of the exhaust gas characteristic values ​​and the correlations determined thereby, the correlations correspond to the characteristics of the pressure application in one or more sections. Thereby, it can be advantageously ascertained in which section(s) a leak is present.

[0043] According to one possible design, each section of the water tube wall through which the cooling water flows has a separate pressure regulator or unit assigned to this section, which is able to apply pressure fluctuations to the pressure inside each section.

[0044] According to one possible design, valves are arranged inside the water tube wall between the sections. These allow different characteristics of pressurization even in connected sections or cooling circuits connected to each other. The installation of the valves divides the cooling circuit into different sections or zones, which can then be checked for leaks individually. Preferably, the exhaust gas characteristic values ​​measured in step b) are the gas velocity and / or the water content and / or the water amount and / or the exhaust gas pressure and / or the exhaust gas temperature and / or carbon monoxide (CO) or carbon dioxide (CO2) or methane (CH4) or sulfur dioxide (SO2). These exhaust gas characteristic values ​​are influenced by water leakage and are therefore suitable as parameters for correlation measurements. In this case, preferably one of the exhaust gas characteristic values ​​evaluated is the water content and / or the water amount, since this shows a particularly strong correlation with the water introduced. This is particularly beneficial for the signal-to-noise ratio.

[0045] However, if other exhaust gas characteristic values ​​are already determined for other reasons, it may also be appropriate and advantageous for these exhaust gas characteristic values ​​to be the basis for such a correlation.

[0046] Optionally, a number of exhaust gas characteristic values ​​are measured, in particular their progression is measured and examined by correlation, whereby the signal-to-noise ratio can be further improved, whereby more accurate and reliable results can be advantageously achieved.

[0047] In the variant of the method where the measured exhaust gas characteristic value is the gas velocity, the following calculation example shows the advantages of the method.

[0048] A typical leak begins with the inflow of about 1-2 liters of water per minute into the reactor vessel. One liter of water flows through the reactor vessel at about 7 m3 under normal pressure. 3 However, when temperatures above 1000°C are present, this results in a volume of water vapor of approximately 420 m 3 If the diameter of the outlet is 4m and the maximum flow rate is 25m per second, the volume of water vapor is 314m per second. 3 The maximum volumetric flow of water vapor is calculated as 1. Depending on the flow profile in the outlet, the actual volumetric flow is about 50% of the maximum, i.e. about 157 m per second. 3 of water vapor or 565,000 m per hour 3 of water vapor. Therefore, the volumetric flow of water vapor introduced by a water leak of 1 liter per minute is only 0.075% of the total volumetric flow of water vapor. If the Bernoulli equation is valid, the flow rate of an incompressible fluid varies proportionally to the square root of the pressure. Therefore, doubling the pressure increases the water leakage rate by a factor of about 1.4, which in an exemplary calculation is about 595 m per second. 3 or to 0.105% of the total volumetric flow of water vapor.

[0049] Due to typical process noise, such a change cannot be detected statistically or reliably even once, but using frequent correlated iterations it can become evident and serve as a reliable indication of leak detection.

[0050] In a variant of the method in which the proportion of water is measured directly by the exhaust gas measuring device, a further increase, i.e. an improved sensitivity of the method can be seen, where it is not necessary to measure the change in the overall composition of the exhaust gas, but only the relative change in the water.

[0051] Other processes that lead to water entering the furnace vessel are e.g. water cooling of gas burners or electrodes, where the water flows from the electrodes into the furnace vessel interior and is evaporated there immediately. This results in an inflow of about 100 liters of water per minute. In addition, the burners can cause an inflow of water of up to 2000 m 3 Up to 10000 methane / h is carried into the reactor vessel.

[0052] Although scrap charges can also result in significantly higher moisture contents on a short time scale, this quickly disappears again within the melting cycle, but the water carryover of such scrap charges is insignificant for the correlation, since it is not related to pressure fluctuations in the cooling water.

[0053] Direct detection of the water volume at the exhaust gas outlet improves the chances of leak detection compared to measuring the total exhaust gas volume throughput at the exhaust gas outlet due to an improved signal-to-noise ratio. Thereby the required pressure fluctuations can be reduced, which minimizes the mechanical load on the components. The cooling water is typically supplied to the cooling water circuit at about 25-35°C and undergoes a temperature increase of about 15°C at nominal throughput. Small fluctuations around the appropriate water pressure are desirable, since an increase in pressure places a large load on the components over a long period of time, but a decrease in pressure leads to an increase in the water outlet temperature. An optimized evaluation is necessary, since a change in water leakage of less than 5% is expected for only a 10% pressure fluctuation.

[0054] According to one preferred variant, the pressure fluctuations are irregular, i.e. the pressure fluctuations applied according to step a) follow a predefined irregular pattern, whereby according to step a) a predefined irregular pressure deviation sequence is applied to the cooling water, so that preferably a time-specific signal arises at the exhaust gas outlet, which has no periodicity and contains a strong signal entropy over a long period of time.

[0055] Similarly, the non-periodic pressure variations repeat after a particular unit of time, the unit of time after which such pressure variations repeat being preferably greater than 30 minutes.

[0056] The measurement cycle does not necessarily have to be selected to be particularly short in order to reduce the risk. It should be noted that accidents due to explosion-like evaporation processes in the furnace vessel do not necessarily occur at every melting cycle. Water leaks can grow undetected over time, which can lead to an increase in the amount of water entering the furnace vessel. However, if water accumulations can form in the lower region of the furnace vessel due to the placement of scrap in the furnace vessel or other geometry that changes depending on the charge, this can lead to spontaneous explosions.

[0057] The time constant must be chosen so that the relative edge steepness of the actual water volume change can still be reliably detected using correlation. The water pressure change signal can range in time from tens of seconds to minutes. Therefore, multiple signal trains from different melting processes can be combined into a signal train that can be correlated.

[0058] An advantageous variant of the method provides for adapting the frequency spectrum to the pressure fluctuations of the water pressure according to step a) and thus adapting the signal of the exhaust gas measuring device, which advantageously results in an improvement of the signal-to-noise ratio.

[0059] The cooling water is preferably passed through the cooling tubes at a pressure of 6 bar. In particular, the pressure fluctuation by means of the pressure regulator according to step a) provides a pressure variation of +2 bar upwards and -2 bar downwards. A suitable pressure fluctuation is in particular the pressure around which the fluctuation takes place, i.e. usually in the range of 10% to 50% of the average value.

[0060] Such changes in water pressure will cause small changes in the hydraulically controlled amount of water flow per unit of time in the event of a leak.

[0061] The application of pressure fluctuations or in particular of irregular sequences of pressure deviations to the cooling water is thereby carried out by means of the pressure regulator described herein, which is also referred to as a pressure regulation device.

[0062] One possible design of the method provides for the correlation according to step c) to be a cross-correlation, whereby if there is a clear maximum in the cross-correlation it can be assumed that a water leak is present, whereby the cross-correlation has extracted a time pattern of the water pressure changes in the exhaust gas signal, i.e. in the signal of the exhaust gas measuring device.

[0063] The use of cross-correlation has the advantage that it allows a useful signal to be obtained even from a strongly disturbed or noisy signal, where it is important to use a sufficient time length of the signal, such that the signal contains sufficient statistical information.

[0064] The reliable formation of the cross-correlation maximum allows a reliable detection of water leaks. Interference signals due to other water intrusions, which are subject to other temporal dynamics, are suppressed by the cross-correlation to such an extent that even small water leaks can be detected. Small water leaks in the sense of the present invention are here leaks with a water outflow of 1 to 10 liters per minute, or 1 to 5 liters per minute or 1 to 2 liters per minute. Preferably, the method of the present invention allows the detection of leaks of at least 3 liters per minute, preferably 1 liter per minute.

[0065] According to one of the advantageous designs of the method, the measurement according to step b) is carried out by means of spectroscopy, which in the sense of the present invention is a measurement method using optical principles that takes into account the individual wavelengths of the evaluated signal, preferably using laser-based emission measurements or laser-based absorption measurements.

[0066] Due to the use of optical measuring systems that function using spectroscopy, the exhaust gas composition of the exhaust gas can be determined by measuring the emission or absorption spectrum in a certain wavelength range. Such optical measuring systems are preferably arranged in or on the exhaust gas pipe. In this case, online or extraction systems can be used, which preferably draw off a partial flow of the exhaust gas through a water-cooled lance. Optical measuring systems are advantageously suitable for enabling a time-resolved analysis of the exhaust gas composition. The amount of water at the exhaust gas outlet can thus be advantageously measured directly.

[0067] One advantageous embodiment of the method provides for the metallurgical melting furnace to be configured as an electric arc furnace with electrodes as heating devices.

[0068] A further aspect of the invention relates to an apparatus for carrying out the method according to the invention, comprising a metallurgical melting furnace, in particular configured as an electric arc furnace, an exhaust gas measuring device for measuring at least one exhaust gas characteristic value in accordance with step b), a pressure regulator for applying pressure fluctuations to the cooling water pressure in accordance with step a), and an evaluation device data-technically connected to the pressure regulator for carrying out the correlation in accordance with step c).

[0069] In this case, the metallurgical melting furnace comprises a furnace vessel and an exhaust gas outlet, the wall of the furnace vessel at least partially consisting of a water tube wall through which cooling water flows, the exhaust gas measuring device is arranged in the flow direction of the exhaust gas after the exhaust gas outlet and is data-technically connected to the evaluation device.

[0070] In particular, the metallurgical melting furnace is configured as an arc furnace with electrodes as heating devices.

[0071] Preferably, the metallurgical melting furnace has a lid, particularly preferably a pivotable lid.

[0072] In this case, the application of a random sequence of pressure fluctuations or in particular pressure deviations to the cooling water is carried out by means of a pressure regulator, which in the sense of the present invention is a device capable of controlling and / or regulating the pressure of the cooling medium flowing through the water tube walls.

[0073] The pressure regulator usually comprises a controlled and / or adjustable main pump in the main line for conveying the cooling water through the water pipes of the water pipe wall. In one possible variant, the pressure change can then be achieved by controlling and / or regulating said main pump. In this case, said main pump is in particular configured in such a way that the start-up of the pump directly leads to a pressure change in the cooling medium and thus to the application of a pressure variation to the cooling water. In this case, the pattern of the pressure variation is therefore achieved by changing or adapting the conveying performance of the main pump. This is a simple way in which the application of the pressure variation can be implemented without the need for the installation of additional components.

[0074] One advantageous design of the pressure regulator provides for it to be configured as a pressure regulating device, which, besides the main pump, has an auxiliary line on the main cooling water line, connected to the cooling circuit, in particular to the water pipe wall, for flowing through a part of the cooling water as in a bypass. The auxiliary line is provided with at least one, optionally several, controllable and / or adjustable valves, which vary the flow through the auxiliary line and therefore also through the main line. Thereby, the pressure in the main cooling line is influenced, so that pressure fluctuations in the cooling water can be generated. The generation of pressure fluctuations by varying the volume flow in the auxiliary line advantageously leads to a situation in which the main pump has to realize less frequent and less intense pressure changes. This advantageously protects the main pump from premature wear.

[0075] One possible design of the pressure regulator provides that the pressure regulator is configured as a pressure regulating device, whereby a change in volume in the cooling water circuit generates the pressure fluctuations. For this, inter alia, a piston, such as a plunger, is arranged to be movable in the volume change area of ​​the water tube wall, so that the movement of the piston changes the volume and, as a result, the pressure in the water tube wall. In this case too, it is advantageous to dispense with the generation of pressure fluctuations by the main pump, which is protected against wear.

[0076] According to one advantageous design, the pressure regulator comprises, besides the main pump for generating the cooling water flow, an auxiliary pump. In this case, the auxiliary pump is configured to be controllable and / or adjustable so that an additional volume flow is generated and thus a pressure fluctuation is generated by the main pump. In this case, inter alia, the auxiliary pump has smaller dimensions than the main pump. Preferably, the auxiliary pump has a pumping capacity of 5% to 20% of the main pump. A smaller auxiliary pump can advantageously be controlled more quickly and accurately, which increases the efficiency of the method.

[0077] In particular, the pressure regulator is configured as a pressure regulator, which comprises, in addition to the main pump, an auxiliary line connected to the cooling circuit and for passing through a part of the cooling water as a bypass on the main cooling water line, on which the auxiliary pump controls and / or regulates the cooling water flow through the auxiliary line. In this case, the generation of pressure fluctuations by the auxiliary pump advantageously results in a larger gradient of the pressure deviation compared to the pressure deviation that can be generated by means of the main pump, and further results in a situation in which the main pump, which has a normally larger dimension, has to realize less frequent and less intense pressure changes for a larger part of the cooling water flow. This advantageously protects the main pump from premature wear. In this case, the auxiliary line is preferably dimensioned such that a throughflow of 5% to 20% of the cooling water is generated by the bypass.

[0078] According to an alternative design, the auxiliary pump is arranged directly on the main cooling water line, with the result that an additional volume flow is also generated by the auxiliary pump and the main pump can be protected from wear due to frequent pressure changes.

[0079] Particularly preferably, the water pipe wall through which the cooling water flows consists of at least two sections, to which different pressure fluctuations can be applied by means of a number of pressure regulators, whereby valves can be arranged between the sections.

[0080] In concept, water leaks in the cooling or water pipes of the reactor vessel are detected by combining and correlating with each other time-resolved measurements of exhaust gas characteristic values, such as the amount of water on the exhaust gas outlet, and regulated pressure fluctuations of the cooling circuit, i.e. pressure changes. The water pressure changes, in the event of a leak, result in a change in the amount of water flowing into the reactor vessel, which is time-correlated with the pressure changes of the cooling circuit. By determining the correlation of these signals, an evaluation device can determine a relationship based on the water leak. In this case, one advantageous design provides for different cooling circuits to which different pressure progression patterns can be applied. This makes it possible, besides detecting the leak, to also detect in which section, i.e. in which cooling circuit the leak has occurred. Thereby, the leak position can be advantageously localized and therefore more efficiently determined.

[0081] Further details, features and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments, taken in conjunction with the associated drawings. [Brief description of the drawings]

[0082] [Figure 1] Metallurgical melting furnace [Diagram 2]Pressure Fluctuations with an Irregular Pattern Figure 1 shows a metallurgical melting furnace 1 for melting metals, with a furnace vessel 2 containing a metal melt 3 and a pivotable lid 4. In the wall area of ​​the furnace vessel 2, a water tube wall 5 through which water flows, i.e. a wall with water tubes 6, is arranged. The water tubes 6 of the water tube wall 5 ensure water cooling by cooling water 7 flowing through them. The furnace vessel 2 is thereby protected from damage due to the high temperatures of the metal melt 3.

[0083] A heating device 6 is arranged on the furnace vessel 2, which has three electrodes 7. The electrodes 7, which protrude into the furnace vessel 2, are preferably designed to supply three-phase alternating current. The electrodes 7 generate an arc 10, the heat of which is used to melt the metal in the furnace vessel 2. Furthermore, a gas burner 11 and an oxygen supply element 12 configured as an oxygen lance 12 are arranged on the furnace vessel 2.

[0084] The exhaust gases resulting from the combustion and melting processes in the furnace vessel 2 are led via an exhaust gas outlet 13 into an exhaust gas line 14. In order to determine exhaust gas characteristic values ​​and to monitor the resulting exhaust gases, an exhaust gas measuring device 15 is further arranged in the exhaust gas line 14 connected to the exhaust gas outlet 13, which is configured to measure one or more exhaust gas characteristic values. In this case, the exhaust gases flow through the exhaust gas outlet 13, pass through an air supply opening 14 (here configured as an air supply ring 16) and then pass by the at least one exhaust gas measuring device 15.

[0085] Alternatively, the exhaust gas measuring device 15 is arranged in front of the air supply opening 16 in the exhaust gas flow direction R. However, arranging the exhaust gas measuring device behind the air supply opening 16 has constructional advantages, since this region of the exhaust gas pipe 14 can be thermally isolated from the furnace vessel 2. This reduces the thermal load on the exhaust gas measuring device 15.

[0086] Downstream of the air supply device, a cooler 17 for cooling the flue gas flow and a filter 18 for separating solid particles from the flue gas are arranged in the flue gas pipe 14. The flue gas is then guided into the chimney via a ventilation fan 19.

[0087] To detect leaks in the water pipe wall 5, pressure fluctuations, in particular a sequence of pressure deviations, are applied to the cooling water 7 flowing into the water pipe 6 of the water pipe wall 5 by means of a pressure regulator 21. The pressure fluctuations of the cooling water 7, i.e. in particular the course of the pressure fluctuations of the cooling water 7 or also the pattern of the sequence of the pressure deviations of the cooling water 7, are compared with the course of exhaust gas characteristic values ​​measured by the exhaust gas measuring device 15. For this purpose, the signal of the exhaust gas characteristic value is transferred by means of a data cable 22 to an evaluation device 23. The course of the pressure fluctuations of the cooling water 7 is likewise transferred from the pressure regulator 21 via the data cable 22 to the evaluation device 23. The evaluation device 23 establishes a correlation between the pressure fluctuations of the cooling water 7, i.e. also referred to as the pressure course, of the defined sequence of pressure deviations of the cooling water 7, and the course of the exhaust gas measurement values ​​measured by the exhaust gas measuring device 15, so that a correlation is found and a reliable detection of the leak is possible.

[0088] 2 shows the progression of pressure 24 when pressure fluctuations having an irregular pattern are applied, where the pressure fluctuations are formed by a number of successive pressure deviations 25, i.e. deviations from a mean pressure 26. Therefore, the progression of pressure 24 acquires a specific pattern.

[0089] Each pressure deviation 25 here has a deviation value 25 and a duration 28, also called period 28. By using a random generator, it is possible to realize an irregular sequence, in which the values ​​generated by the random generator between a minimum 29 and a maximum 30, for example between a minimum and a maximum deviation value and / or between a minimum and a maximum duration, determine the sequence of pressure deviations 25. For this purpose, a certain minimum unit can be defined, in which for example 8 or 10 values ​​are selected randomly.

[0090] The pressure deviations 25 shown here do not have any spacing between each other. However, it is also possible to have spacing between the pressure deviations 25 without any variation from the average value, i.e. the mean pressure 26. These spacings can be varied as well. According to one simple design of the method, only the spacing between the pressure deviations 25 can be varied. [Explanation of symbols]

[0091] 1 Metallurgical melting furnaces, electric arc furnaces 2 Furnace vessel 3. Metal melt 4 Lid 5 Water pipe wall 6 water tube 7 Cooling water 8 Heating Devices 9 electrodes 10. Arc 11 Gas burner 12 Oxygen supply element, oxygen lance 13 Exhaust gas outlet 14 Exhaust gas pipe 15 Exhaust Gas Measurement Devices 16 Air supply opening, air supply ring 17 Cooler 18 Filters 19 Ventilator 20 Chimney 21 Pressure Regulator 22 Data Cable 23 Evaluation Devices 24 Pressure 25 Pressure Deviation 26 Mean Pressure 27 Standard deviation 28 period 29 min 30 max R Exhaust gas flow direction

Claims

1. a metallurgical melting furnace (1) comprising a furnace vessel (2) and an exhaust gas outlet (13), the walls of said furnace vessel (2) consisting at least in part of a water tube wall (5) through which cooling water (7) flows; an exhaust gas measuring device (15) arranged in the flow direction (R) of the exhaust gas after the exhaust gas outlet (13) for measuring at least one exhaust gas characteristic value; a pressure regulator (21) for adjusting the pressure of the cooling water (7) in the water tube wall (5); and an evaluation device (23) connected in a data-technical manner to the exhaust gas measuring device (15) and to the pressure regulator (21); A method for detecting water leaks in a metallurgical melting furnace (1) using Next steps: a) applying pressure variations to the cooling water (7) using the pressure regulator (21), where the pressure variations are a sequence of temporary pressure deviations from a mean pressure; b) measuring the course of exhaust gas characteristic values ​​with the exhaust gas measuring device (15); c) determining by the evaluation device (23) a correlation between the course of the pressure fluctuations of the cooling water (7) and the course of the exhaust gas characteristic values; d) outputting said correlation by said evaluation device (23); The method comprising:

2. 2. The method of claim 1, wherein the pressure variations applied according to step a) follow a predetermined irregular pattern.

3. 3. The method according to claim 2, characterized in that a random generator is used to generate the irregular sequence of pressure deviations (25).

4. 4. The method according to claim 1, characterized in that inside the water tube wall (5) at least two different sections are traversed by the cooling water (7), to which different pressure variations are applied according to step a) and for each of said sections a correlation is carried out according to step c).

5. 5. The method according to claim 4, characterized in that in the water pipe wall (5) valves are arranged between the sections.

6. 6. The method according to claim 1, wherein the exhaust gas characteristic values ​​measured in step b) are the gas velocity and / or the water content and / or the water amount.

7. The method according to any one of claims 1 to 6, characterized in that the pressure variations in step a) are not periodic.

8. Method according to any one of the preceding claims, characterized in that the correlation according to step c) is a cross-correlation.

9. 9. The method according to claim 1, wherein the measurement according to step b) is carried out using a spectroscopic method.

10. 10. The method of claim 9, wherein the measurement is a laser-based emission measurement or a laser-based absorption measurement.

11. The method according to any one of claims 1 to 10, characterized in that the metallurgical melting furnace (1) is configured as an electric arc furnace (1) with electrodes (9) as heating devices (8).

12. An apparatus for carrying out the method according to any one of claims 1 to 11, comprising: A metallurgical melting furnace (1) with a furnace vessel (2) and an exhaust gas outlet (13), the walls of which consist at least in part of a water tube wall (5) through which cooling water (7) flows; and an exhaust gas measuring device (15) arranged in the flow direction (R) of the exhaust gas after said exhaust gas outlet (13) for measuring at least one exhaust gas characteristic value according to step b); a pressure regulator (21) for applying a pressure variation to the pressure of said cooling water (7) according to step a); and an evaluation device (23) connected in data-technical terms to said pressure regulator (21) and to said exhaust gas measuring device (15) for carrying out the correlation according to step c); The apparatus comprising:

13. 13. The apparatus according to claim 12, characterized in that the pressure regulator comprises a main pump and an auxiliary pump, the auxiliary pump being configured to be controllable and / or adjustable such that a volume flow additionally generated by the auxiliary pump generates a pressure fluctuation.

14. 14. The device according to claim 12 or 13, characterized in that the pressure regulator (21) comprises an auxiliary line connected to the water pipe wall, and a valve is configured and arranged in the auxiliary line such that the throughflow through the auxiliary line can be controlled and / or adjusted by the valve.

15. 15. The device according to claim 14, characterized in that the pressure regulator (21) comprises a volume change area, in which a piston is constructed and arranged so that a volume change caused by the movement of the piston affects the pressure at the water tube wall.

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