FURNACE SYSTEM AND METHOD FOR OPERATING A FURNACE

Abstract

The invention relates to a method for operating a furnace (12), comprising a furnace chamber (14), which is heated by means of at least one burner (16), wherein the method comprises a monitoring of a combustion in the furnace chamber (14), and monitoring a calorific value of a fuel determined for the burner (16). The invention further relates to a furnace system (10), and to a control unit (24).

Claims

1. Method for operating a furnace (12) having a furnace chamber (14) which is heated by means of at least one burner (16), wherein the method comprises monitoring combustion in the furnace chamber (14) and monitoring a calorific value of a fuel intended for the burner (16).

2. Method according to claim 1, further comprising regulating the burner (16) as a function of the combustion in the furnace chamber (14) and as a function of the calorific value of the fuel intended for the burner (16).

3. Method according to claim 2, wherein the regulation of the burner (16) comprises regulating an oxygen supply to the burner (16), and/or regulating a fuel supply to the burner (16), and/or regulating an additional fuel supply.

4. Method according to claim 1, wherein monitoring the calorific value of the fuel intended for the burner (16) comprises precombusting a part of the fuel intended for the burner (16), and preferably comprises ascertaining an oxygen demand for the precombustion.

5. Method according to claim 4, wherein the part of the fuel intended for the burner (16) is diverted for the precombustion from the remaining part of the fuel intended for the burner (16) before the remaining part of the part of the fuel intended for the burner (16) is supplied to the burner (16).

6. Method according to claim 1, further comprising regulating an oxygen supply into the furnace chamber (14) as a function of the combustion in the furnace chamber (14).

7. Method according to claim 1, wherein monitoring the combustion in the furnace chamber (14) comprises measuring at least one exhaust gas parameter of exhaust gases which are produced during combustion in the furnace chamber (14), wherein preferably at least one exhaust gas parameter comprises a concentration of carbon monoxide, and/or oxygen, and/or carbon dioxide, and/or nitrogen oxide.

8. Method according to claim 1, wherein a metallic feedstock is at least partially melted in the furnace chamber (14) when the furnace (12) is operating.

9. Control unit (24) for operating a furnace (12) having a furnace chamber (14) which is heated by means of at least one burner (16), wherein the control unit (24) is designed to carry out a method according to claim 1.

10. Control unit (24) according to claim 9, wherein the control unit comprises a control device and/or several control devices connected via a communications link.

11. Furnace system (10) comprising: a furnace (12) having a furnace chamber (14); a burner (16) for heating the furnace chamber (14); a control unit (24) according to claim 9.

12. Furnace system (10) according to claim 11, further comprising a precombustor (22) designed to precombust a part of the fuel intended for the burner (16), and wherein the furnace system (10) is preferably designed to ascertain an oxygen demand for the precombustion.

Description

DESCRIPTION OF THE FIGURES

[0033] FIG. 1 shows a furnace system according to a first preferred embodiment.

[0034] FIG. 2 shows a furnace system according to a second preferred embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 shows a schematic illustration of a furnace system 10 according to a first preferred embodiment. The furnace system 10 has a furnace 12 which forms or has a furnace chamber 14. Furthermore, the furnace system 10 has a burner 16 which is arranged on or integrated into the furnace 12 and is designed to heat the furnace chamber 14. The burner is supplied with fuel or oxygen, which are intended for combustion in the burner 16, via a fuel supply line or fuel line 18 and an oxygen supply line or oxygen line 20, in order to cause heat to be input via the burner 16 into the furnace chamber 14. In this case, pure oxygen does not necessarily have to be supplied to the burner 16 via the oxygen line 20, but a mixture having oxygen may, for example, also be sufficient to be combusted in the burner 16 with the fuel from the fuel line 18. For example, the burner 16 may be supplied with air via the fuel line 20.

[0036] Both the fuel line 18 and the oxygen line 20 have a branch 18a or 20a, respectively, via which fuel or oxygen is diverted from the fuel line 18 or the oxygen line 20 and supplied to a precombustor 22. The portions of the fuel and of the oxygen which are diverted via the branches 18a and 20a from the fuel or oxygen to be supplied to the burner 16 are preferably very low, so that, nevertheless, the greatest portion of the fuel and oxygen to be supplied to the burner is available for combustion in burners. Precombustion of the diverted portions of the fuel and oxygen then takes place in the precombustor 22, wherein the calorific value of fuel is ascertained or monitored. In particular, the diversion of fuel and oxygen can take place continuously—in particular, when the burner 16 is in operation—in order to preferably allow permanent or continuous monitoring of the fuel and/or oxygen that is to be supplied or is supplied to the burner 16. The findings concerning the fuel ascertained during precombustion in the precombustor 22 can then be forwarded by the precombustor 22 to a control unit 24 which can, for example, store, and/or evaluate, and/or further use the data, and/or measured values, and/or findings received from the precombustor 22.

[0037] In the embodiment shown, the control unit 24 is, furthermore, connected to an exhaust gas sensor 26 which is arranged in and/or at an exhaust gas outlet 28 of the furnace 12 and is designed to at least partially measure or monitor the exhaust gases 30 flowing in the direction 100 out of the furnace chamber 14, and, in this way, to monitor or characterize the combustion in the furnace chamber 14. The exhaust gas sensor 26 preferably transmits data and/or findings about the combustion in the furnace chamber 14 to the control unit 24, which data and/or findings can then be stored, and/or evaluated, and/or further used by the control unit 24.

[0038] The control unit 24 is designed in such a way that the control unit 24 regulates the burner 16 on the basis of or as a function of the data or findings concerning the calorific value of the fuel transmitted by the precombustor 22, and on the basis of or as a function of the data or findings concerning the combustion in the furnace chamber 14 ascertained by the exhaust gas sensor 26 (fuel quantity, composition and/or stoichiometry) in order to achieve optimal combustion of the fuel in the burner 16 and, accordingly, optimal generation of heat and/or flame 32 and, in this way, optimize the combustion process or melting process of the feedstock 34 in the furnace chamber.

[0039] For example, the burner 16 may have means by which the combustion of the fuel in the burner 16, and/or the supply of fuel to the burner 16, and/or the supply of oxygen to the burner 16 can be adapted by means of regulation by the control unit 24. Alternatively or additionally, such means may be provided separately from the burner 16—for example, via controllable valves (not shown) in the fuel line 18 and/or in the oxygen line 20.

[0040] The control unit 24 can be designed to calculate an energy content of the heated and/or molten metal or feedstock based upon the employed fuel and/or oxygen amounts, and to propose from this calculated energy content the next steps of the melting cycle, such as a charge release for the next batch and/or combustion performance and/or an oxygen quantity, a temperature curve to be attained, and/or a composition of the furnace atmosphere to be provided or exhaust gas values to be achieved.

[0041] In addition, the furnace system 10 has a control path 25 for a volume flow and/or pressure of the oxygen or the air and/or the fuel, which are supplied to the burner 16. This control path 25 can, for example, be controlled or regulated or monitored by the control unit 24.

[0042] FIG. 2 shows a schematic representation of a furnace system 10 according to a second preferred embodiment. Explanations regarding elements which have already been explained with reference to FIG. 1 also apply to the embodiment shown in FIG. 2, unless they are replaced by other explanations.

[0043] The shown furnace system 10 has a plurality of sensors which serve to monitor the combustion in the furnace chamber 14 and/or the calorific value. For example, the furnace system 10 has a pressure sensor 36 which is designed to ascertain a pressure difference between the interior of the furnace chamber 14 and the outside environment of the furnace 12. In addition, the furnace system 10 has one or more furnace temperature sensors 38 which are used to measure the temperature in and/or on the furnace chamber 14. In addition, an exhaust gas temperature sensor 40 is arranged at the exhaust gas outlet 28 to ascertain the temperature of the exhaust gases 30 flowing through the exhaust gas outlet 28. The furnace system 10 also has a further exhaust gas sensor 26 which is designed, in particular, to ascertain portions or concentrations of various gases in the exhaust gases 30, such as the concentrations of carbon monoxide, and/or oxygen, and/or carbon dioxide, and/or nitrogen oxides.

[0044] All said sensors are connected in a communications network to the control unit 24 which, among other things, receives and processes, and/or forwards, and/or stores the measured values or data ascertained by said sensors.

[0045] Furthermore, the furnace system 10 according to the second preferred embodiment has a precombustion analyzer 44 which is designed to analyze the exhaust gases from precombustion produced in the precombustor 22 and, in particular, to ascertain the portions or concentrations of carbon monoxide, and/or carbon dioxide, and/or hydrogen in the exhaust gases from precombustion, and also to provide them to the control unit 24 via the communications network 42.

[0046] The control unit 24 is designed in this case to ascertain suitable parameters for the regulation of the combustion furnace chamber 14 and, in particular, for the operation of the burner 16 on the basis of the received data or measured values of the aforementioned sensors and the precombustion analyzer 44, and to appropriately control the corresponding elements in order to correspondingly regulate the desired combustion in the furnace chamber 14 and the combustion in the burner 16. For this purpose, for example, the burner 16 can be connected to the communications network 42 or to the control unit 24 via a separate burner regulator 46 so that the burner regulator 46 controls or regulates or adapts the combustion process in the burner 16 on the basis of control commands which the burner regulator 46 receives from the control unit 24. In addition, the burner regulator 46 may be designed to return data to the control unit 24 via the communications network 42, which data, for example, provide information about the operation, and/or the behavior, and/or possible disturbances of the burner 16. According to other preferred embodiments, the burner regulator 46 or its functionality can also be integrated into the control unit 24 or be taken over by the control unit 24.

[0047] Furthermore, the furnace system 10 has controllable valves 18b and 20b by means of which the flows of fuel and oxygen via the fuel line 18 or the oxygen line 20 can be adapted, and/or controlled, and/or regulated in order to thereby be able to adapt to the operation or the combustion process in burner 16. Furthermore, via an additional controllable or regulatable additional fuel line 18c, a further additional fuel can be added to the fuel supplied via the fuel line 18 to the burner 16 in order, for example, to change the calorific value of the fuel. For example, when a low-grade fuel is supplied to the burner 16 via the fuel line 18, natural gas, and/or hydrogen, and/or propane, and/or other hydrocarbons can be added to the fuel in order to increase its calorific value and adapt it to the desired or required calorific value. Accordingly, the oxygen line 20 has an additional line 20c via which, for example, pure oxygen can be added to the gas flowing through the oxygen line 20 as needed in order, for example, to allow efficient combustion of the fuel and the optionally added, additional fuel in the burner 16. These controllable or regulatable additional lines 18c and 20c are also connected via the communications network 42 to the control unit 24 and can preferably be controlled or regulated thereby.

[0048] In addition, the furnace system 10 has a controllable and/or regulatable oxygen lance 48 via which oxygen and/or an oxygen-containing gas mixture can be directly injected into the furnace chamber 14 in order, for example, to supply oxygen to the combustion in the furnace chamber 14 without it having to pass through the burner 16.

REFERENCE NUMBERS

[0049] 10 Furnace system [0050] 12 Furnace [0051] 14 Furnace chamber [0052] 16 Burner [0053] 18 Fuel line [0054] 20 Oxygen line [0055] 22 Precombustor [0056] 24 Control unit [0057] 25 Mechanical control path for air/oxygen and fuel [0058] 26 Exhaust gas sensor [0059] 28 Exhaust gas outlet [0060] 30 Exhaust gases [0061] 32 Flame [0062] 34 Feedstock [0063] 36 Pressure sensor [0064] 38 Furnace temperature sensor [0065] 40 Exhaust gas temperature sensor [0066] 42 Communications network [0067] 44 Precombustion analyzer [0068] 46 Burner regulator [0069] 48 Oxygen lance [0070] 100 Flow direction of the exhaust gases