METHOD FOR CONTROLLING A COMBUSTION AND FURNACE

Abstract

The invention relates to a method for controlling a combustion in a furnace (100) which is heated by a burner (160) with at least one oxygen lance (120), wherein a fuel is supplied via a fuel supply (110) of the burner (110) and oxygen is supplied at least in part with a high speed of 100 m/s or more by the at least one oxygen lance (120), and wherein oxygen in an overstoichiometric range is supplied. The invention further relates to a furnace (100) for carrying out said method.

Claims

1-12. (canceled)

13. A method of closed-loop control of combustion in a furnace (100) heated by a burner (160) having at least one oxygen lance (120), compromising: supplying fuel by a fuel feed (110) of the burner (160); and supplying oxygen at least partly at a speed of at least 100 ms through the at least one oxygen lance (120), wherein the supplying the oxygen is in a superstoichiometric range.

14. The method of claim 13, wherein the oxygen is at least partly supplied at a speed in the region of the speed of sound in oxygen of between 290 m/s and 320 m/s.

15. The method of claim 13, wherein the burner comprises a plurality of the oxygen lances (120) through which the oxygen is supplied.

16. The method of claim 13, further comprising actuating the oxygen supply under automatic closed-loop control via an offgas measurement.

17. The method of claim 16, further comprising measuring a content of the oxygen in the offgas measurement.

18. The method of claim 16, further comprising measuring a CO content and/or a content of other reaction gases in the offgas measurement.

19. The method of claim 13, further comprising actuating the oxygen supply under automatic closed-loop control via a measurement of a flame signal.

20. The method of claim 19, further comprising measuring the flame signal with a UV light sensor.

21. The method of claim 13, further comprising manually actuating the oxygen supply.

22. The method of claim 13, wherein the furnace (100) comprises a rotary drum furnace.

23. The method of claim 13, wherein the furnace (100) melts contaminated aluminum scrap (101).

24. A furnace (100) having closed-loop control of combustion in the furnace, comprising: a burner (160) having at least one oxygen lance (120), the burner (160) configured to supply fuel via a fuel supply (110), and the at least one oxygen lance (120) configured to supply oxygen at a speed of at least 100 m/s through the at least one oxygen lance (120); a sensor unit (140) for detection of a stoichiometry; and a control unit (150) to adjust the oxygen supply responsive to a signal from the sensor unit (140) such that an oxygen concentration supplied is within a superstoichiometric range.

Description

DESCRIPTION OF FIGURES

[0027] FIG. 1 shows a schematic of a preferred configuration of a furnace of the invention which is in the form of a rotary drum furnace and is set up to perform a preferred embodiment of a method of the invention.

[0028] The sole FIGURE, FIG. 1, shows a schematic of a furnace in the form of a rotary drum furnace, labeled 100. The rotary drum furnace 100 in this specific example is set up to melt contaminated aluminum scrap 101. By means of a door 102, the aluminum scrap 101 can be introduced into the rotary drum furnace 100. In addition, the rotary drum furnace 100 is closed by means of the door 102. The rotary drum furnace 100 also has a burner 160 having a fuel supply 110 that may be disposed in the door 102, for example.

[0029] The burner 110 takes the form of an LTOF burner and also has an oxygen supply in the form of at least one oxygen lance 120. By means of the oxygen lance 120, an amount of oxygen is supplied to the rotary drum furnace 100. The oxygen is supplied at a high speed of 100 m/s or more. More particularly, the amount of oxygen is such that oxygen is supplied in a superstoichiometric range.

[0030] The burner flames 111 and 121 from the burner 110 heat the aluminum scrap 101, which leads to pyrolysis of the aluminum scrap 101, especially of organic components of the aluminum scrap 101. This forms carbon monoxide as combustion gas. Offgas is removed via an offgas duct 103 in an offgas stream from the rotary drum furnace 100.

[0031] By virtue of the high speed or high momentum with which the amount of oxygen is supplied to the rotary drum furnace through the oxygen lance 120, the carbon monoxide and the other combustion gases circulates in the rotary drum furnace 100 and is sucked in by the gas flowing out of the oxygen lance 120. Since the oxygen is injected at high speed (above 100 m/s), no flame in the conventional sense can form; instead, a semi-flameless flame (not shown) propagates with high convection. The rotary drum furnace or a control unit 150 are set up to perform a preferred embodiment of a method of the invention.

[0032] In this embodiment, a sensor device 140 is disposed in the offgas duct 103, where it detects an amount of oxygen or an amount of carbon monoxide. This sensor device 140, which may possibly also be a UV probe, is connected to the control unit 150 via a connection 154.

[0033] The particular amount of carbon monoxide and other reaction gases is utilized to adjust the amount of oxygen supplied through the oxygen lance 120, especially in the course of closed-loop control. Depending on the determined amount of carbon monoxide and other reaction gases, the control unit 150 calculates the amount of oxygen to supply oxygen in a superstoichiometric ratio. Accordingly, the control unit 150 actuates the oxygen lance 120, indicated by reference numeral 152, in order that the determined amount of oxygen is supplied to the rotary drum furnace 100.

[0034] In addition, the control unit 150 appropriately controls a rotary motion of the rotary drum furnace 100, indicated by reference numeral 155.

[0035] In addition, as well as the sensor device 140, an oxygen inlet may also be provided, by means of which a small amount of oxygen can be added, in order to ignite CO in the event of the presence thereof, and to produce a flame visible to the sensor device 140 and hence to start the closed-loop control process.