FURNACE AND METHOD FOR OPERATING A FURNACE

Abstract

The invention relates to a method for operating a furnace (10), in particular an anode furnace, the furnace being formed by a plurality of heating channels (12) and furnace chambers, the furnace chambers serving to receive carbonaceous bodies, in particular anodes, and the heating channels serving to control the temperature of the furnace chambers, the furnace comprising at least one furnace unit (11), the furnace unit comprising a heating zone (18), a fire zone (19) and a cooling zone (20), which for their part are formed by at least one section (37, 38, 39, 40, 41, 42) comprising furnace chambers, a suction ramp (15) of the furnace unit being disposed in a section of the heating zone, and a burner ramp (16) of the furnace unit being disposed in a section of the fire zone, process air in the heating channels of the fire zone being heated by means of the burner ramp, and exhaust gas being suctioned from the heating channels of the heating zone by means of the suction ramp, an operation of the ramps being controlled by means of a control device of the furnace unit, a temperature in the heating channel being measured in the fire zone, an output of the burner ramp being regulated according to the temperature measured in the heating channel by means of a regulator of the control device, wherein, by means of the control device, at least two characteristic numbers are determined and the characteristic numbers are compared, a status of the heating channel relative to an amount of fuel in the heating channel being determined on the basis of the comparison by means of the control device, a characteristic number including the temperature in the heating channel and/or a characteristic number including the output of the burner ramp and/or a characteristic number including a controlled variable of the regulator being determined as characteristic numbers. Furthermore, the invention relates to a control device for operating a furnace and to a furnace.

Claims

1. A method for operating a furnace (10), in particular an anode furnace, the furnace being formed by a plurality of heating channels (12) and furnace chambers (13), the furnace chambers serving to receive carbonaceous bodies, in particular anodes, and the heating channels serving to control the temperature of the furnace chambers, the furnace comprising at least one furnace unit (11), the furnace unit comprising a heating zone (18), a fire zone to (19) and a cooling zone (20), which for their part are formed by at least one section (37, 38, 39, 40, 41, 42) comprising furnace chambers, a suction ramp (15) of the furnace unit being disposed in a section of the heating zone, and a burner ramp (16) of the furnace unit being disposed in a section of the fire zone, process air in the heating channels of the fire zone being heated by means of the burner ramp, and exhaust gas being suctioned from the heating channels of the heating zone by means of the suction ramp, an operation of the ramps being controlled by means of a control device of the furnace unit, a temperature in the heating channel being measured in the fire zone, an output of the burner ramp being regulated according to the temperature measured in the heating channel by means of a regulator of the control device, characterized in that by means of the control device, at least two characteristic numbers are determined and the characteristic numbers are compared, a status of the heating channel relative to an amount of fuel in the heating channel being determined on the basis of the comparison by means of the control device, a characteristic number including the temperature in the heating channel and/or a characteristic number including the output of the burner ramp and/or a characteristic number including a controlled variable of the regulator being determined as characteristic numbers.

2. The method according to claim 1, characterized in that by means of the control device, the at least two characteristic numbers are continuously determined and the characteristic numbers are continuously compared.

3. The method according to claim 1 or 2, characterized in that process air is heated in the heating channels (12) by means of burners (30) of the burner ramp (16), a regulator and a measuring element (31) being assigned to each burner, a temperature in the heating channel being measured by means of said measuring element (31), by means of the respective regulator, a respective output of the burners being regulated according to the temperature measured with the measuring element.

4. The method according to any one of the preceding claims, characterized in that the method is carried out with two or more burner ramps (16).

5. The method according to any one of the preceding claims, characterized in that the control device compares the characteristic numbers determined by the control device with signs of characteristic numbers and/or characteristic numbers preset in a matrix, the status of the heating channel (12) being determined on the basis of the comparison.

6. The method according to any one of the preceding claims, characterized in that the control device standardizes a value of the respective characteristic numbers by it lying within a tolerance band stored in the control device for the respective characteristic number.

7. The method according to any one of the preceding claims, characterized in that the control device determines an exceedance of a limit value for the amount of fuel in the heating channel (12) on the basis of the comparison.

8. The method according to claim 7, characterized in that a gradient (gradT) of the temperature in the heating channel (12) and/or a gradient (gradY) of the output of the burner ramp (16) are determined as characteristic numbers.

9. The method according to claim 7 or 8, characterized in that a control deviation (Xw) of the regulator and a product (Cd) of the control deviation (Xw) and a control value (Y) of the output of the burner ramp (16) of the regulator are determined as characteristic numbers.

10. The method according to claim 9, characterized in that a control deviation (Xw) of the regulator and a product (C1) of the control deviation (Xw) and a difference of a control value (Y.sub.i1) of the output of a first burner (30) from a control value (Y.sub.i) of the output of a second burner (30) of the regulator are determined as characteristic numbers, the first burner being disposed at a heating channel (12) in the flow direction of the process air downstream of the second burner.

11. The method according to claim 10, characterized in that the control device determines a feedback of regulators of burners (30) if the product (C1) is > a value of the product (C1) stored in the control device.

12. The method according to any one of claims 7 to 11, characterized in that a control deviation (Xw) of the regulator and a product (Ct) of the control deviation (Xw) and a gradient (gradT) of the temperature in the heating channel (12) are determined as characteristic numbers.

13. The method according to any one of claims 9 to 11 and 12, characterized in that the control device determines the exceedance of a limit value if the fire zone (19) spans heating channels (12) which run straight and if the fire zone spans heating channels which run in a bending manner via a collecting channel.

14. The method according to claim 13, characterized in that the control device determines an exceedance of a limit value for the amount of fuel in the heating channel (12) in the case of a negative temperature gradient if the product (Cd) is <a value of the product (Cd) stored in the control device and the product (Ct) is >0.

15. The method according to claim 13 or 14, characterized in that the control device determines an exceedance of a limit value for the amount of fuel in the heating channel (12) in the case of a positive temperature gradient if the product (Cd) is <than a value of the product (Cd) stored in the control device and the product (Ct) is 0.

16. The method according to any one of the preceding claims, characterized in that the output of the burner ramp (16) is adjusted by means of the control device in such a manner that a target ratio of the process air and the amount of fuel in the heating channel (12) is reached, said target ratio being preset in the control device.

17. The method according to claim 16, characterized in that the adjustment is made by lowering, increasing and/or dynamically limiting a respective output of burners (30) of the burner ramp (16) by means of the regulator.

18. A control device for operating a furnace (10), in particular an anode furnace, the furnace being formed by a plurality of heating channels (12) and furnace chambers (13), the furnace chambers serving to receive carbonaceous bodies, in particular anodes, and the heating channels serving to control the temperature of the furnace chambers, the furnace comprising at least one furnace unit (11), the furnace unit comprising a heating zone (18), a fire zone (19) and a cooling zone (20), which for their part are formed by at least one section (37, 38, 39, 40, 41, 42) comprising furnace chambers, a suction ramp (15) of the furnace unit being disposed in a section of the heating zone, and a burner ramp (16) of the furnace unit being disposed in a section of the fire zone, process air in the heating channels of the fire zone being heatable by means of the burner ramp, and exhaust gas being capable of being suctioned from the heating channels of the heating zone by means of the suction ramp, an operation of the ramps being controllable by means of the control device of the furnace unit, a temperature in the heating channel being measurable in the fire zone by means of measuring elements (31) of the burner ramp, an output of the burner ramp being capable of being regulated according to the temperature measured in the heating channel by means of a regulator of the control device, characterized in that by means of the control device, at least two characteristic numbers are determinable and the characteristic numbers are comparable, a status of the heating channel relative to an amount of fuel in the heating channel being determinable on the basis of the comparison by means of the control device, a characteristic number including the temperature in the heating channel and/or a characteristic number including the output of the burner ramp and/or a characteristic number including a controlled variable of the regulator being determinable as characteristic numbers.

19. A furnace (10), in particular an anode furnace, comprising a control device according to claim 18.

Description

[0051] FIG. 1: shows a schematic illustration of a furnace in a perspective view;

[0052] FIG. 2: shows a schematic illustration of furnace unit of the furnace in a longitudinal section view;

[0053] FIG. 3: shows a temperature distribution in the furnace unit.

[0054] A combined view of FIGS. 1 and 2 shows a schematic illustration of an anode furnace or furnace 10 comprising a furnace unit 11. Furnace 10 has a plurality of heating channels 12, which extend parallel to each other along interposed furnace chambers 13. In this case, furnace chambers 13 serve to receive anodes or carbonaceous bodies (not shown in more detail). Heating channels 12 extend in a meandering shape in the longitudinal direction of furnace 10 and have heating channel openings 14 at regular intervals, which are each covered by a heating channel cover (not shown in more detail).

[0055] Furnace unit 11 further comprises a suction ramp 15, one or multiple burner ramps 16 and a cooling ramp 17. Their positions on furnace 10 functionally define a heating zone 18, a fire zone 19 and a cooling zone respectively. In the course of the production process of the anodes or carbonaceous bodies, furnace unit 11 is displaced in the longitudinal direction of furnace 10 relative to furnace chambers 13 or the carbonaceous bodies by shifting suction ramp 15, burner ramps 16 and cooling ramp 17 with the result that all anodes or carbonaceous bodies located in anode furnace 10 pass through zones 18 to 20.

[0056] Suction ramp 15 is essentially formed by a suction channel 21, which is connected to an exhaust gas cleaning system (not shown in the case at hand) via an annular channel 22. Suction channel 21 for its part is connected to a heating channel opening 14 via a connecting channel 23 in each case, a throttle valve 24 being disposed on connecting channel 23 in the case at hand. Furthermore, a measuring element (not shown in the case at hand) for pressure measuring is disposed within collecting channel 21, and another measuring element 25 for temperature measuring is disposed in each heating channel 12 directly upstream of collecting channel 21 and is connected thereto via a data line 26. Moreover, a measuring ramp 27 comprising measuring elements 28 for each heating channel 12 is disposed in heating zone 18. A pressure and a temperature in the respective heating channel 12 can be determined by means of measuring ramp 27.

[0057] According to the illustration in FIG. 1, furnace unit 11 is disposed in such a manner that heating channels 12 run straight along furnace unit 11. Heating channels 12 end in collecting channels 29 of furnace 10 such that the process air flowing through heating channels 12 enters a collecting channel 29 and is, from there, again diverted into heating channels 12 when furnace unit 11 is disposed in the area of a collecting channel 29 and/or spans it. In this case, heating channels 12 run essentially in a bending manner and/or in opposite directions in the area of furnace unit 11.

[0058] Three burner ramps 16 comprising burners 30 and measuring elements 31 for each heating channel 12 are placed in fire zone 19. Burners 30 each burn a flammable fuel in heating channel 12, a burner temperature being measured by means of measuring element 31. This makes it possible for to a desired burner temperature to be set or regulated for each of the burners 30 in the area of fire zone 19. The burner temperature is regulated by means of a regulator (not shown in the case at hand), in particular a PID controller, for each of the burners 30.

[0059] Cooling zone 20 comprises cooling ramp 17, which is formed by a feeding channel 32 comprising respective connecting channels 33 and throttle valves 34 for being connected to heating channels 12. Fresh air is blown into heating channels 12 via feeding channel 32. The fresh air cools heating channels 12 or the anodes or carbonaceous bodies located in furnace chambers 13 in the area of cooling zone 20, the fresh air continuously heating up until it reaches fire zone 19. In this context, FIG. 3 shows a diagram of the temperature distribution relative to the length of heating channel 12 and zones 18 to 20. Furthermore, a measuring ramp 35 or what is referred to as a zero pressure ramp comprising measuring elements 36 is disposed in cooling zone 20. Measuring elements 36 serve to detect a pressure in respective heating channels 12. The pressure in heating channel 12 is therefore essentially 0 in the area of measuring elements 36, a high pressure forming between measuring elements 36 and cooling ramp 17, and a low pressure forming in heating channels 12 between measuring elements 36 and suction ramp 15. Consequently, the fresh air flows from cooling ramp 17 through heating channels 12 toward suction ramp 15. Ramps 15 to 17 are each disposed in sections 37 to 42, sections 37 to 42 for their part each being formed by heating channel portions 12. Sections adjacent to sections 37 to 42 are not shown in more detail in the case at hand for the sake of clarity of FIG. 2.

[0060] During an operation of furnace 10, suction ramp 15, burner ramp 16 and cooling ramp 17 are controlled by means of a control device of furnace unit 11 (not shown in the case at hand), the control device comprising at least one means for data processing, such as a programmable logic controller or a computer, which is used to execute a computer program product or at least one software. In fire zone 19, a temperature in heating channel 12 is measured by means of the control device, an output of the burner being regulated according to the temperature measured in heating channel 12 by means of the regulators of burners 30 (also not shown in the case at hand) or the control device. The control device determines at least two characteristic numbers and compares the characteristic numbers, a status of the respective heating channel 12 relative to an amount of fuel in heating channel 12 being determined on the basis of the comparison by means of the control device. The control device uses a characteristic number including the temperature in the heating channel and/or a characteristic number including the output of burner ramp 16 or burners 30 and/or a characteristic number including a controlled variable of the regulator as characteristic numbers. The respective characteristic numbers are determined by means of the control device by measurement and/or calculation. The determination of the at least two characteristic numbers by means of the control device is carried out continuously, as is the comparison of the characteristic numbers. On the basis of the comparison, the control device determines an exceedance of a limit value for the amount of fuel in the heating channel and/or the presence of a so-called flooding situation.

[0061] A gradient (gradT) of the temperature in a heating channel 12 and a gradient (gradY) of the output of burner ramp 16 or burners 30 can be determined as characteristic numbers by the control device. Furthermore, a control deviation (Xw) of the regulator and a product (Cd) of the control deviation (Xw) and a control value (Y) of the output of burner ramp 16 or burners 30 of the regulator can be determined as characteristic numbers. It is also possible that a control deviation (Xw) of the regulator and a product (C1) of the control deviation (Xw) and a difference of a control value (Y.sub.i1) of the output of a first burner 30 from a control value (Y.sub.i) of the output of a second burner 30 of the regulator are determined as characteristic numbers, first burner 30 being disposed at a heating channel 12 in a flow direction of the process air downstream of second burner 30. Moreover, the control device can determine a feedback of regulators of burners 30 if the product (C1) is a value of the product (C1) stored in the control device. In addition, a control deviation (Xw) of the regulator and a product (Ct) of the control deviation (Xw) and a gradient (gradT) of the temperature in heating channel 12 can be determined from characteristic numbers. Due to the continuous determination of these characteristic numbers by means of the control device, it is possible to identify directly and reliably the presence of a flooding situation independently of a position of furnace unit 11 at heating channels 12.