EP2761241A1 - Monitoring method - Google Patents

Abstract

The invention relates to a method for monitoring an operating state of an anode firing furnace, wherein the anode firing furnace is formed from a plurality of heating ducts (12) and furnace chambers, wherein the furnace chambers are used to hold anodes and the heating ducts are used to control the temperature of the furnace chambers, wherein the anode firing furnace comprises at least one furnace unit (11) having a heating zone (18), a firing zone (19) and a cooling zone (20), wherein a suction device (15) is arranged in the heating zone and a burner device (16) is arranged in the firing zone, wherein, by means of the burner device, combustion air is heated in the heating ducts of the firing zone, wherein, by means of the suction device, hot air is sucked out of the heating ducts of the heating zone, wherein a suction output of the suction device is determined and wherein a pressure in the heating duct is measured, wherein a volume flow in the heating duct is determined from a ratio of suction output and pressure.

Description

 monitoring procedures

The invention relates to a method for monitoring an operating szustandes an anode furnace, wherein the anode furnace is formed of a plurality of heating channels and furnace chambers, wherein the furnace chambers for receiving anodes and the heating channels for controlling the temperature of the furnace chambers, wherein the anode furnace at least one furnace unit with a Heating zone, a fire zone and a

Cooling zone comprises, wherein in the heating zone from a suction device and in the fire zone, a burner device is arranged, wherein by means of the burner combustion air is heated in the heating channels of the fire zone, and wherein by means of the suction device from the hot air is sucked from the heating channels of the heating zone.

The present process finds application in the production of anodes needed for fused-salt electrolysis to produce primary aluminum. These anodes are prepared from petroleum coke with the addition of pitch as binder in a molding process as so-called "green anodes" or "raw aodes", which are subsequently sintered in an anode furnace in the molding process. This sintering process takes place in a defined heat treatment process in which the anodes pass through three phases, namely a heating phase, a sintering phase and a cooling phase.

Here are the Rohanoden in a heating zone of an assembled from the heating zone, a fire zone and a cooling zone, anode furnace formed "fire" and are preheated by the originating from the fire zone waste heat of already finished sintered anodes before the preheated anodes in the fire zone on the Sintering temperature of about 1200 ° Cel sius be heated in accordance with the state of the art, as in game swei se from the

 EP 1 785 685 A1, the various zones mentioned above are defined by a successively alternating arrangement of different units above furnace chambers or heating channels which receive the anodes. By positioning a burner device above selected furnace chambers or heating channels, the fire zone is defined, which is arranged between the heating zone and the cooling zone. In the cooling zone are immediately before burned, ie heated to sintering temperature, anodes. Above the cooling zone, a blower device is arranged, by means of which air is blown into the heating channels of the cooling zone. The air is directed through an arranged above the heating from the suction device through the heating channels of the cooling zone through the fire zone into the heating zone and passed from this as a flue gas through a flue gas cleaning system and discharged into the environment. From the suction device and the burner device together with the blower device and the heating channels form a furnace unit.

The aforementioned aggregates are displaced along the heating channels in the direction of the anode arranged in the anode crucible at regular intervals. Thus, it may be provided that an anode furnace comprises a plurality of furnace units, the aggregates of each other Subsequently, above the furnace chambers or heating channels for subsequent heat treatments of the raw anode or anodes are moved. In the case of such anode kilns, which may be designed in different designs as an open anode kiln or anode ring kiln, there is the problem that a volumetric flow of the air guided through the anode kiln can only be measured with unacceptably high outlay. A B estimmung the volume flow is needed in particular for the regular monitoring of an operating condition of the anode furnace. This is to ensure that sufficient oxygen is available for combustion of a fuel of the burner device in the heating channels of the anode furnace. Since a direct volume flow measurement is not possible due to the meandering, rectangular geometry of the heating channels, an attempt is made to determine the volume flow by an indirect measurement, for example a pressure measurement. Such an estimate of the

Volumetric flow often leads to unusable results, for example, when a heating channel cover is opened or improperly closed, or a heating channel is blocked or blocked. Even a measurement of the volume flow by means of a Venturi tube leads to unsatisfactory results, since the differential pressures necessary for the measurement can not be established. In practice, therefore, a volumetric flow rate is carried out by trained oven personnel in the context of a Ofenrundgangs at regular Zeitab states. If a malfunction of the anode furnace is detected, it is then turned off manually by the furnace personnel. However, this can lead to hazardous operating conditions of the anode furnace, which can lead to deflagration, fires or explosions, may not be detected in time.

Object of the present invention is therefore to propose a method for monitoring an operating szustandes an anode furnace, which allows continuous monitoring of the operating condition. This object is achieved by a method with the features of claim 1 dissolved.

In the method according to the invention for monitoring an operating state of an anode furnace, the anode furnace is formed from a plurality of heating channels and furnace chambers, the furnace chambers for receiving anodes and the heating channels for controlling the temperature of the furnace chambers, wherein the anode furnace at least one furnace unit with a heating zone, a Fire zone and a cooling zone, wherein in the heating zone from a suction device and arranged in the fire zone, a burner means i st, wherein medium s the burner means combustion air is heated in the heating channels of the fire zone, being sucked by means of the suction hot air from the heating channels of the heating zone, wherein a suction power from the suction device is determined, and wherein a pressure in the heating channel is measured, wherein from a ratio of suction power and pressure from a volume flow in the heating channel is determined.

The suction of the suction is relatively reliable determinable because the suction device from indeed causes a volume flow in the heating channels, j edoch is not regulated in direct dependence of the flow rate. Therefore, a suction of the

Set from suction device on the assumption that this results in the desired volume flow. So it is also possible to determine the suction power of the suction easily and accurately. Furthermore, a pressure or a vacuum caused by the suction device is measured in the heating channel. From the ratio of suction flow to pressure, the volume flow in the heating channel can be determined comparatively accurately. For example, if a Heizkanalabdeckung open or improperly verschlo Ssen or the heating channel is clogged, there is a change in the pressure in the heating channel relative to the suction power from the suction device Ab. The measured pressure in the heating channel thus deviates from a presumed pressure at the same suction capacity. from. From this, a reduced or increased volume flow in the heating channel can be derived. The respective corresponding size of the volumetric flow results from a deviation from the presumed volumetric flow at known suction power and measured pressure. Since the determination of the suction power and the measurement of the pressure in the heating channel can be carried out continuously, via transducers and thus without furnace personnel, it is thus possible to carry out a constant monitoring of the operating state of the anode combustion furnace by the continuous determination of the volume flow.

Due to the various embodiments of the method, a pressure or negative pressure in the heating channel in the heating zone and / or the fire zone can be measured. Thus, it is conceivable to carry out a plurality of pressure measurements in the relevant zone or the respective zones in order to quickly determine the position of a malfunction.

Furthermore, it is also possible for a closer determination of an operating state to measure a pressure or negative pressure in, for example, an air channel of the suction device. If the suction device from is designed so that it spans a plurality of heating channels in the transverse direction and is connected thereto, the pressure measured in this collecting duct from the suction device can also be used to determine the volume flow. Furthermore, it can also be ensured that there is no malfunction when the suction power and the measured pressure in the suction device from Ab is in an expected relationship to each other.

The volume flow can be determined even more accurately if this is determined from a ratio of suction power and pressure in the suction device and the ratio of suction power and pressure in the heating duct. The respective conditions can in each case be formed separately from one another and the volumetric flow can be derived therefrom. Also, a volumetric flow can be determined individually for individual heating channels, for example, by setting a respective pressure in a plurality of heating channels in relation to the pressure in the suction device. A particularly high or low pressure in a heating channel compared to the other heating channels can already indicate a possible malfunction in the relevant heating channel. Next, a pressure deviation in a heating channel effects on the pressures in the other heating channels, so that here with relative reference to the suction pressure measured in the Ab a accordingly changed flow can be determined or calculated.

A B estimmung from the suction from the suction device can be done by determining a flap position of a throttle from the suction device. A cross section from a suction channel can be varied by adjusting the throttle, so that from the suction power of the suction device from Ab depends, inter alia, on the set cross-section of the suction channel from. If a throttle valve or similar such device is used, therefore, from a flap position, for example, indicated in angular degrees relative to the suction channel from, on a sauglei be inferred from stung. A flap position can be determined particularly simply and accurately, for example by means of a rotary potentiometer.

It is particularly advantageous if the volume flow in the heating channel of the heating zone and / or the fire zone is determined. Since, as the case may be, the volume flow differences caused by the combustion process result here, these can thus be taken into account. Thus, a volume flow in the heating channel of the aforementioned zones can in each case be determined separately from one another. Thus, a more differentiated consideration of the operating state in the respective zones of the anode furnace becomes possible. Overall, an operating state can be derived from the ratio of suction power and pressure and / or the specific volume flow. Thus, it is possible to determine, based on the measured data or the volume flow, in which phase of the anode production of the anode furnace or the relevant furnace unit is currently located. For example, the determination of the operating condition can be used to determine a point in time for converting the suction device and the burner device as well as a blower device even more accurately. In a further embodiment of the method, a temperature in the heating channel can be measured. An assessment of an operating szustandes is thereby further simplified, since such a required firing temperature can be monitored.

Furthermore, a temperature gradient in the heating channel can also be measured. Accordingly, a temperature profile can be monitored over a period of time, with a falling or rising temperature or a negative or positive temperature gradient allowing conclusions to be drawn about a change in operation.

The temperature gradient and / or the temperature can or can be measured in a collecting duct of the suction device and / or the heating zone and / or the fire zone. The collecting duct or the aforementioned zones require a specific temperature gradient or temperature range, in each case for a proper operation of the furnace unit, so that an even more accurate determination of an operating state is possible with a metrological monitoring of these sections.

Also, the volumetric flow can be determined even more accurately if a change in density of air in the heating channel is calculated from the temperature gradient and the temperature, and this density change is taken into account in the determination of the volumetric flow. Which is through an increase or decrease in a temperature in the heating channel resulting volume change of the air located in the heating channel can significantly affect a flow in the heating channel. A calculation of the volumetric flow can therefore be corrected by a correction factor, which can be derived from a calculation of the density change on the basis of temperature gradient and temperature.

From a ratio of temperature gradient and volume flow, a B setriebszustand can be derived. Depending on the volume flow in the heating channel, there is a progressive heating in the heating zone. Consequently, a relationship between temperature gradient and volume flow can be established. For example, a negative or very high temperature gradient in the heating zone at a low flow rate may indicate a blockage of the relevant heating channel. The ratio formation of the temperature gradient and the volume flow can therefore even be used to determine a possible cause of a malfunction.

In this context, it is advantageous if the operating state is evaluated, wherein, in the event of a deviation from a presumed operating state, a switch-off of the burner device takes place. Thus it can be avoided that a malfunction of the furnace unit has a possible damage to the same result. From the circuit of the burner device or the entire furnace unit can also be done automatically without oven staff must be on site. In this respect, it may be provided that processing of the measured values and operating state variables detected in the context of the monitoring method takes place by means of a device for data processing or a corresponding control and regulating device. Thus, the operation szustand can also be influenced or corrected automatically by influencing control of the relevant units of the furnace unit. It is also possible to store the operating state parameters describing the operating state, wherein an evaluation of the current operating state can be carried out by comparing the stored operating state parameters with the current operating state. In particular, if a device for data processing is used, a continuous comparison of the current operating state parameters with the stored operating state parameters can be carried out. In this case, it is possible to define threshold values for the various operating state parameters, which trigger a disconnection or corrective control of units.

Advantageously, a plausibility check of transducers can also be carried out prior to each start or startup or recommissioning of the furnace unit. It can thus be ensured that, after the aggregates of the furnace unit have been transferred, the transducers of the furnace unit are connected to one another in the intended manner. Among other things, it can thus be ensured that, in the event of a malfunction of a measuring transducer, there is no undesired operating state influencing.

Hereinafter, a preferred embodiment of the invention will be explained in more detail with reference to the accompanying drawings.

Show it:

Fig. 1: A schematic representation of an anode furnace in a perspective view;

FIG. 2 is a schematic representation of a furnace unit of the anode furnace in a longitudinal sectional view; FIG.

3 shows a temperature distribution in the furnace unit;

4 shows a graphic representation of the ratio of volume flow to operating state parameters; 5: a graphical representation of the ratio of volume flow to temperature gradient;

6 shows a flowchart for an embodiment of the method for monitoring a operating state.

A synopsis of FIGS. 1 and 2 shows a schematic representation of an anode furnace 10 with a furnace unit 11. The anode baking oven 10 has a plurality of heating channels 12 extending in parallel along intermediate furnace chambers 13. The oven chambers 13 serve to receive anodes not shown here. The heating channels 12 extend in a meandering manner in the longitudinal direction of the anode furnace 10 and have at regular intervals from heating channel openings 14, which are in each case covered with a heating channel cover, not shown here.

The furnace unit 1 1 further comprises a suction device from 1 5, a burner device 16 and a blower 17. Their position at the anode furnace 10 defines in each case functionally a heating zone 1 8, a fire zone 19 and a cooling zone 20. In the course of the production process of the anodes the furnace unit 1 1 relative to the furnace chambers 13 and the anodes displaced by reacting the devices 1 5 to 17 in the longitudinal direction of the anode furnace 10, so that all anodes located in the anode furnace 10, the zones 1 8 to 20 run through.

The suction device 1 5 is essentially formed from a collecting channel 21 which is connected via an annular channel 22 to an exhaust gas purification system not shown here. The collecting channel 21 is in turn connected in each case via a connecting channel 23 to a heating channel opening 14, wherein here a throttle valve 24 is arranged on the connecting channel 23. Furthermore, a measuring sensor, not shown here, for measuring the pressure within the collecting channel 21 and another measuring sensor 25 for measuring the temperature in each heating Channel 12 is arranged immediately in front of the collecting channel 21 and connected via a data line 26 with this. In addition, a measuring ramp 27 with measuring sensors 28 for each heating channel 12 is arranged in the heating zone 18. By means of the measuring ramp 27, a pressure and a temperature in the relevant section from the heating channel 12 can be determined.

The burner device 16 comprises three burner ramps 29 with burners 30 and transducers 3 1 for each heating channel 12. The burners 30 in each case burn a flammable fuel in the heating channel 12, a burner temperature being measured by means of the transducers 3 1. It thus becomes possible to set a desired burner temperature in the area of the fire zone 19.

The cooling zone 20 comprises the blower device 17, which is formed from a feed channel 32 with respective connecting channels 33 and throttle valves 34 for connection to the heating channels 12. Fresh air is blown into the heating channels 12 via the feed channel 32. The fresh air cools the heating channels 12 and the anodes located in the furnace chambers 13 in the region of the cooling zone 20, wherein the fresh air is continuously heated until it reaches the fire zone 19. FIG. 3 is a diagram of the temperature distribution based on the length of a heating channel 12 and the zones 1 8 to 20 refer to this.

Furthermore, a measuring ramp 35 with transducers 36 is arranged in the cooling zone 20. The transducers 36 serve to detect a pressure in the respective heating channels 12. In the region of the transducers 36, the pressure in the heating channel 12 essentially assumes the value zero, wherein between the transducers 36 and the fan 17 an overpressure and between the transducers 36 and from the suction device 1 5 a negative pressure in the heating channels 12 is formed. Consequently, the fresh air flows from the fan 17 through the heating channels 12 to the suction device from 1 5 5. With the method sequence shown by way of example in FIG. 6, it is now possible to determine a volume flow of the air and thus a working condition. With reference to the anode furnace according to FIGS. 1 and 2, a check of all transducers 25, 28, 3 1, 36 as well as the transducer, not shown here for determining the position of the throttle valve 24 from the suction device 1 is carried out first 5. So it can be ensured that no measured values of possibly defective transducers are read out. This test takes place immediately after the furnace unit 1 1 has been moved and the devices 1 5 to 17 have been put into operation again. During operation of the furnace unit 11, a temperature in the heating channel 12 and a temperature gradient by means of the measuring sensor 25 or 28 detected, these measurements being used to density correction of the air in the heating channel 12 or hot air. In parallel with this, a measurement of a position of the respective throttle valves 24, a pressure measurement in the collecting channel 21 and a pressure measurement in the heating channels 12 are carried out by means of the measuring transducer 28. From the measured values for the throttle valve position and the respective measured values for a negative pressure in the collecting channel 21 and in the heating channel 12 in each case relations are formed, which together with the above-described

Density correction can derive a volume flow in the heating channel 12. From a ratio of volume flow and temperature gradient in the heating channel 12, in turn, a B sszustand is determined for the flow rate. Here is provided, the corresponding measured values or

Store operating state parameters and thus to calibrate an operating state or to describe a proper operating state. During repetitive operation, it is then possible to make a comparison between the calibrated or assumed proper operating state and the current operating state.

For example, as shown in FIG. 4, this comparison may be made by comparing a current operating pressure to a throttle flap with a presumed operating pressure. It is also possible to evaluate a ratio of volume flow and temperature gradient as shown in FIG. 5. In the example shown, the ratio in a region 37 of the graph could be considered to be proper for the operating state, critical in a region 38 and unsatisfactory in a region 39. These operating states can be signaled, for example, as a graphical representation in the manner of a traffic light or acoustically to an operator.

Claims

claims A method of monitoring an operating condition of an anode furnace (10), wherein the anode furnace is formed of a plurality of heating channels (12) and furnace chambers (13), the furnace chambers for receiving anodes and the heating channels for controlling the temperature of the furnace chambers, wherein the anode furnace comprises at least one furnace unit (11) with a heating zone (18), a fire zone (19) and a cooling zone (20), wherein in the heating zone a suction device (15) and in the fire zone a burner device (16) is arranged, wherein combustion air is heated in the heating channels of the fire zone by means of the burner device, hot air being sucked out of the heating channels of the heating zone by means of the suction device,  characterized, that a suction of the suction device is determined, and that a pressure in the heating channel is measured, wherein from a ratio of suction and pressure, a volume flow in the heating channel is determined. 2. The method according to claim 1,  characterized,  that a pressure in the heating channel (12) of the heating zone (18) and / or the fire zone (19) is measured. 3. The method according to claim 2,  characterized,  that a pressure in the suction device (15) is measured. 4. The method according to claim 3,  characterized,  in that the volume flow in the heating channel is determined from a ratio of suction power and pressure in the suction device (15) and the ratio of suction power and pressure in the heating duct (12). 5. The method according to claim 3 or 4,  characterized,  a respective pressure in a plurality of heating channels (12) is set in relation to the pressure in the suction device (15). 6. The method according to any one of the preceding claims,  characterized,  a determination of the suction power of the suction device (15) is carried out by determining a flap position of a throttle flap (24) of the suction device (15). 7. The method according to any one of the preceding claims,  characterized, that the volume flow in the heating channel (12) of the heating zone (18) and / or the fire zone (19) is determined. 8. The method according to any one of the preceding claims, characterized  that an operating state is derived from the ratio and / or the volume flow. 9. The method according to any one of the preceding claims,  characterized,  that a temperature in the heating channel (12) is measured. 10. The method according to claim 9,  characterized,  that a temperature gradient in the heating channel (12) is measured. 11. The method according to claim 10,  characterized,  that the temperature gradient and / or the temperature in a collecting channel (21) of the suction device (15) and / or the heating zone (18) and / or the fire zone (19) is measured. 12. The method according to claim 10 or 11,  characterized,  a temperature change of air in the heating channel (12) is calculated from the temperature gradient and the temperature, the density change being used to determine the volume flow. 13. The method according to any one of claims 10 to 12,  characterized, that an operating state is derived from a ratio of temperature gradient and volume flow. 14. The method according to claim 8 or 13,  characterized,  that the operating state is evaluated, wherein in the case of deviation from a presumed operating state, a shutdown of the burner device (16) takes place. 15. The method according to claim 14,  characterized,  that the operating state descriptive operating state parameters are stored, wherein an assessment of the current operating state by a comparison of the stored with the current operating state parameters takes place. 16. The method according to any one of the preceding claims,  characterized,  a plausibility check of transducers (25, 28, 31, 36) is carried out before the furnace unit (11) is put into operation.