DE102008018889A1 - Furnace for heating aluminum strands, comprises a burner nozzle for the combustion of an air-fuel mixture in a combustion chamber, a lambda probe for analysis of flue gas composition, and a transporting means - Google Patents

Abstract

The furnace comprises a burner nozzle (5) for the combustion of an air-fuel mixture in a combustion chamber (2), a lambda probe (29) for analysis of flue gas composition, and a means for transporting aluminum strands through the combustion chamber. The lambda probe is arranged to a pilot combustion chamber (27) with a pilot burner nozzle (26). The pilot combustion chamber is configured for forming the flue gas composition unperturbed from the combustion chamber. The lambda probe analyzes the flue gas composition in the pilot combustion chamber and/or in an exhaust pipe of the chamber. The furnace comprises a burner nozzle (5) for the combustion of an air-fuel mixture in a combustion chamber (2), a lambda probe (29) for analysis of flue gas composition, and a means for transporting aluminum strands through the combustion chamber. The lambda probe is arranged to a pilot combustion chamber (27) with a pilot burner nozzle (26). The pilot combustion chamber is configured for forming the flue gas composition unperturbed from the combustion chamber. The lambda probe analyzes the flue gas composition in the pilot combustion chamber and/or in an exhaust pipe of the chamber. The lambda probe is a wideband probe. The lambda probe is a part of a control device for regulating the air-fuel ratio of the air-fuel mixture. The pilot burner nozzle is a reduced embodiment of the burner nozzle. The air-fuel mixture is supplied into the pilot burner nozzle and/or burner nozzle. The control device adjusts the air volume flow, pressure, fuel flow rate and/or fuel pressure. A catalyst is provided for cleaning the flue gas. A pipeline is provided for supplying the air-fuel mixture to the burner nozzle. A side pipeline branches off from the pipeline for supplying the air-fuel mixture to the pilot burner nozzle. An independent claim is included for a system for treating aluminum strands.

Description

The The invention relates to a furnace layer with a burner nozzle for combustion of an air-fuel mixture in a combustion chamber and with a lambda probe for analyzing a flue gas composition. The invention also relates to a plant for treating strands. Such a plant comprises a furnace, with which a strand, In particular, a continuous casting rod or continuous casting bolt in front of a Further treatment, for example by scissors or press, can be heated to forming temperature.

A furnace of the type mentioned is basically from the DE 10 2004 020 206 A1 and the DE 20 2004 006 551 U1 known. In the known furnace system, it is a question of a system for heat treating continuously cast bars or continuous casting bolts, which can be heated to a forming temperature before shearing the billet and then pressing in a press in the furnace. In the kiln plant a plurality of circumferentially rotatably arranged shaft elements for axially transporting the continuous casting rods or continuous casting bolts is provided.

to Optimization of combustion, it is known to provide a lambda probe, with which the flue gas composition within the combustion chamber is analyzed becomes. In particular, the lambda probe serves the ratio from air to fuel in the flue gas for a lambda control to determine. It has been found that by the lambda probe obtained measurement result is subject to great fluctuations. This in turn leads to the setting of the air-fuel mixture not is optimal, with the result that the fuel in the combustion chamber incomplete burns and thus the pollution of the flue gas is high. Furthermore, the observed phenomenon leads to an increased fuel consumption.

At this point is the invention of whose task it is a Furnace plant to propose, in which an improved, in particular more reliable analysis of the flue gas composition is realized. In particular, this combustion is optimized, the fuel consumption reduced and pollutant emissions are minimized. It also exists the task is to provide a correspondingly improved treatment facility of strands.

The Task is with regard to the furnace of the aforementioned Art solved by the lambda probe a pilot combustion chamber associated with a pilot burner nozzle.

Regarding the plant for treating strands, in particular of Continuous Casting Bars or Continuous Casting Studs will complete the task the provision of a furnace installation according to the invention solved.

The Invention has recognized that the variations in the measurement results of Lambda probe for false air or ambient air influences are due in the combustion chamber. To these, the Measuring results falsifying air influences comes it through the air through the unavoidable openings the combustion chamber connecting the combustion chamber to the environment. For example is in the combustion chamber an opening for a temperature measuring device provided by the ambient air can penetrate. Further are in a furnace, which is part of a treatment plant of strands is a kiln inlet opening to Supply of a strand or bolt to be heated and an outlet opening for the strand or Bolt provided. Through these openings can large amounts of ambient air enter the combustion chamber, which falsify the measurement result and thus to a faulty measurement and thus to a maladjustment of the air-fuel ratio to lead. To an exact, of environmental influences to be able to carry out at least largely free measurement of the flue gas, suggests the invention, not that of the at least to analyze a flue gas generated in the combustion chamber of a burner nozzle, but the lambda probe separate from the combustion chamber pilot combustion chamber assign in which an air-fuel mixture from a pilot burner nozzle is burned.

Of the Pilot combustion chamber is arranged separately from the combustion chamber, that in the pilot combustion chamber a largely undisturbed from the combustion chamber Forming a flue gas composition (eg, in particular oxygen, Nitrogen and / or other flue gas components) possible is.

To may, but need not, the pilot burn outside the Be formed combustion chamber. A pilot burn room can, however, completely or partially, be arranged in the combustion chamber and thereby, for forming the undisturbed flue gas composition, sufficient from be separated residual combustion chamber, z. B. by partial walls, Baffles or the like, optionally teilpermeable walls, or the like - this independent of a pilot combustion chamber outlet, which can be advantageously open to the combustion chamber.

The pilot combustion chamber is characterized in particular in that it has no inlet or outlet opening for insertion or removal of metal strands or bolts. Preference is given to the environmental influences on the combustion inside half of the pilot combustion chamber is reduced by the fact that the pilot combustion chamber has only one exhaust gas outlet opening. According to the concept of the invention, the measurement of the flue gas composition is thus independent of the Faluftuft- or ambient air in the combustion chamber feasible, so that an accurate determination of the air-fuel ratio, in particular by determining the residual oxygen content in the flue gas generated by the pilot burner nozzle is possible. This in turn ensures an optimized air-fuel ratio control and thus an optimized combustion of the burner nozzle, which in turn leads to a reduced fuel consumption and a reduced pollutant content in the flue gas.

advantageous Further developments of the invention are the dependent claims in detail, the furnace system according to the Develop the concept of the invention within the scope of the task.

In Development of the invention is provided with advantage that the Lambda probe directly analyzes the flue gas composition in the pilot combustion chamber, to determine the ratio of air to fuel. It is also conceivable the flue gas composition in one of the pilot combustion chamber wegführenden exhaust pipe using the lambda probe to measure. In particular, by means of the lambda probe, the residual oxygen content the flue gas composition measured. It is from the lambda probe generates an analog or digital voltage signal, which then, in particular, in a later to be explained Control device is further processed or evaluated.

tries have shown that particularly accurate measurement results are achieved can if the lambda probe is designed as a jump probe is. The voltage generated by the lambda probe is through described the Nernst equation. The jump probe is characterized that in a very narrow transition range around lambda = 1, the so-called lambda window, the voltage characteristic extremely is steep. The voltage changes in this transition region abruptly as a function of the air-fuel ratio.

Preferably However, a broadband probe is provided for the development of the invention, because this one more appropriate for the purposes of the scheme Output characteristic has.

Preferably, the lambda probe operates such that the residual oxygen content or CO ₂ content of the flue gas is compared with the oxygen content of the ambient air, wherein the ambient air is supplied either through an opening directly in the lambda probe or via a feed line of the lambda probe.

Around the flue gas composition in the pilot combustion chamber of the at least a burner nozzle in the combustion chamber produced flue gas composition replicate as exactly as possible, is in the development of Invention provided that the pilot burner nozzle, at least approximately, a scaled down embodiment the burner nozzle is, so the flue gas composition in the pilot room corresponds to the flue gas composition in the combustion chamber or at least easily convertible. The usage a small burner nozzle as a pilot burner nozzle has the further advantage that the fuel consumption for the determination of the flue gas composition in the pilot combustion chamber is minimal is.

According to one advantageous embodiment of the invention is provided that the lambda probe part of a control device for regulating the air-fuel ratio the burner nozzle supplied air-fuel mixture is. The fuel is preferably gaseous Fuel, but also liquid fuel such as Fuel oil or heavy oil can be used. By means of the control device, the air-fuel ratio, especially with regard to optimal combustion (Lambda regulation).

It has proven to be particularly advantageous, the pilot combustion chamber with pilot burner nozzle parallel to the at least one burner nozzle to switch the furnace system. In other words, the Pilot burner nozzle supplied the same air-fuel mixture, like the at least one burner nozzle in the combustion chamber of the furnace, so that the results determined by the lambda probe on the Flue gas composition in the combustion chamber transferable or possibly are convertible.

In Embodiment of the invention is the parallel connection of the burner nozzle and the pilot burner nozzle achieved in that the pilot burner nozzle over a side pipe is supplied with an air-fuel mixture. In this case, the side line branches with advantage of the at least a burner nozzle in the combustion chamber leading air-fuel mixture line from. Preferably, the cross section of the side conduit is less than the cross section leading to the burner nozzle Air-fuel mixture pipe (main).

In order to exploit the waste heat of the flue gas generated in the pilot combustion chamber and thus to increase the efficiency of the furnace, it is advantageously provided that the flue gas generated in the pilot combustion chamber is discharged into the combustion chamber and thus in a system for Treatment of strands in addition to heating the strands is exploited.

The Supply of the flue gas of the pilot combustion chamber in the combustion chamber is particularly advantageous if the combustion chamber in training the invention downstream of a catalyst for flue gas cleaning is, so that the flue gas formed in the pilot combustion chamber also the catalyst is supplied. By providing a Catalyst can pollutant emissions of the flue gas drastically reduced.

The Invention also leads to a plant for treating Strands with a shearing and / or pressing arrangement for forming continuous casting bars or bolts, the shearing and / or pressing arrangement with a lambda probe associated with a pilot space previously described a pilot space for analyzing the flue gas composition of a pilot burner nozzle Is provided.

embodiments The invention will now be described below with reference to the drawing. This is not necessarily an embodiment to scale, rather the drawing is probably for explanation, in schematic and / or slightly distorted shape. With regard to supplements the teachings directly recognizable from the drawing will be referred to the pertinent ones Referenced prior art. It is important to take into account the varied modifications and changes concerning the shape and the detail of an embodiment can be made without departing from the general idea to deviate from the invention. The in the description, in the drawing as well in the claims disclosed features of the invention can both individually and in any combination for the Embodiment of the invention be essential. In particular, apply all values within specified ranges are disclosed as and can individually as well as as any area with each other Combined and essential for the embodiment of the invention be and be claimed. The general idea of the invention is not limited to the exact shape or detail of the following shown and described, preferred embodiment or limited to an object restricted would be compared to that claimed in the claims Object.

Further Advantages, features and details of the invention will become apparent the following description of a preferred embodiment as well as the drawing.

This shows in the only one 1 a schematic structure of a furnace as part of a plant for treating strands.

In 1 is an open system with the reference numeral 1 generally marked. The open system 1 includes a combustion chamber 2 with a plurality of axially adjacent control zones, of which in this exemplary embodiment, by way of example, a control zone 3 is shown. Inside the combustion chamber 3 is a strand preferably formed of an aluminum alloy 4 stored, by means of a transport device, not shown, to a likewise not shown, the furnace system 1 downstream forming device is transportable. The combustion chamber 2 is provided at its axial end sides with furnace doors, not shown, around the strand 4 in the direction of thrust S in the combustion chamber into and out of this addition to the forming device to transport.

In the axial direction along the strand 4 is in the combustion chamber 2 a number of burner nozzles 5 arranged. The burner nozzles 5 Be with an air-fuel mixture over an air-fuel mixture pipe 6 provided.

The air-fuel mixture pipe 6 includes a compensator tube section 7 to compensate for changes in length and angle due to temperature influences.

The air-fuel mixture pipe 6 is a mixer 8th upstream, in which a fuel line 9 for in this embodiment, gaseous fuel and an air line 10 lead. The fuel is preferably propane or natural gas. In the mixer 8th be through the air line 10 supplied air and through the fuel line 9 supplied fuel uniformly mixed to form an air-fuel mixture to be burned. In an entrance area of the air duct 10 there is a fan 11 who has an adequate supply of the mixer 8th ensures with ambient air. Further, in the air line 10 an air throttle 12 arranged by means of an air servo motor 13 is adjustable, causing the in the mixer 8th reaching air volume is adjustable. The air pressure inside the air line 10 is by means of an air pressure measuring device 16 measurable, the axial between the fan 11 and the air throttle 12 is arranged.

In the fuel line 9 is a fuel throttle 14 integrated, by means of a fuel servo motor 15 is adjustable, causing the in the mixer 8th reaching fuel quantity is adjustable. In the air line 10 is still in the air flow direction immediately before the mixer 8th a first pressure monitor 23 , A second pressure switch 24 is directly to the mixer 8th downstream in the air-fuel mixture line 6 , The pressure monitors 23 . 24 have the task to monitor a minimum and maximum pressure.

Further, in the fuel line 10 in the fuel flow direction in front of the fuel throttle 14 a ball valve 17 , two series gas solenoid valves 18 . 19 , a flow meter 20 , a check valve 21 as well as a constant pressure or low pressure regulator 22 integrated.

From the air-fuel mixture pipe 6 branches immediately before the Kompensatorrohrabschnitt 7 a side line 25 whose cross section is substantially smaller than the cross section of the air-fuel mixture line 6 , The side line 25 supplies a pilot burner nozzle 26 with an air-fuel mixture from the air-fuel mixture pipe 6 , The pilot burner nozzle 26 therefore burns the same air-fuel mixture as the number of burner nozzles 5 , The pilot burner nozzle 26 is in this respect the number of burner nozzles 5 connected in parallel. The pilot burner nozzle 26 burns the air-fuel mixture in a pilot combustion chamber 27 In this embodiment, with advantage completely outside and thus separate from the combustion chamber 2 is arranged. It is also possible to separate this, except for an exhaust pipe 28 enclosed space within or in the area of the combustion chamber 2 to arrange. The inside of the pilot burn room 27 resulting flue gas is via the exhaust pipe 28 in the combustion chamber 2 directed and serves there for additional warming of the strand 4 , The inside of the combustion chamber 27 resulting flue gas as well as in the combustion chamber 2 resulting flue gas are passed through a catalyst, not shown, to reduce pollutant emissions.

In the pilot burn room 27 opens a lambda probe 29 , The designed as a broadband probe lambda probe 19 generates a voltage signal λ, which is proportional to the air-fuel ratio in the flue gas of the pilot burner nozzle 26 is. Alternatively, the lambda probe and the flue gas within the exhaust pipe 28 the pilot burn room 27 measure up.

The voltage signal λ becomes a logic unit 30 fed, like the lambda probe 29 Part of a control device 31 is. As a function of the voltage signal λ, the fuel actuating motor is activated in this exemplary embodiment, whereby by adjusting the fuel throttle valve 14 the air-fuel ratio in the air-fuel mixture line is changed. Additionally or alternatively, the air actuator motor 13 be driven, causing the in the mixer 8th reaching air volume via an adjustment of the air throttle 12 is varied.

Because of the lambda probe 29 the flue gas composition within the pilot combustion chamber 27 or optionally the exhaust pipe 28 measures, is at least largely free from external interference influences voltage signal λ obtained on the basis of the logic unit 30 regulating the air-fuel ratio.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004020206 A1 [0002]
• - DE 202004006551 U1 [0002]

Claims (12)

Furnace plant, in particular for heating aluminum strands with a burner nozzle ( 5 ) for combustion of an air-fuel mixture in a combustion chamber ( 2 ) and with a lambda probe ( 29 ) for analyzing a flue gas composition, characterized in that the lambda probe ( 29 ) a pilot burn room ( 27 ) with a pilot burner nozzle ( 26 ), wherein the pilot combustion chamber is designed to form a combustion gas chamber undisturbed flue gas composition. Furnace installation according to claim 1, characterized in that the lambda probe ( 29 ) the flue gas composition in the pilot combustion chamber ( 27 ) and / or in an exhaust pipe ( 28 ) of the pilot combustion chamber ( 27 ) analyzed. Furnace installation according to one of claims 1 or 2, characterized in that the lambda probe ( 29 ) is designed as a broadband probe. Furnace installation according to one of the preceding claims, characterized in that the pilot burner nozzle ( 26 ), at least approximately, a downsized embodiment of the burner nozzle ( 5 ). Furnace installation according to one of the preceding claims, characterized in that the lambda probe ( 29 ) Part of a control device ( 31 ) is for controlling the air-fuel ratio of the air-fuel mixture. Furnace installation according to claim 5, characterized in that with the control device ( 31 ) the air volume flow and / or the air pressure and / or the fuel volume flow and / or the fuel pressure is adjustable. Furnace installation according to one of the preceding claims, characterized in that the pilot burner nozzle ( 26 ) and the burner nozzle ( 5 ), the same air-fuel mixture can be fed. Furnace installation according to one of the preceding claims, characterized in that an air-fuel mixture line ( 6 ) for supplying the burner nozzle ( 5 ) is provided with the air-fuel mixture, and that of the air-fuel mixture line ( 6 ) a side line ( 25 ) for supplying the pilot burner nozzle ( 26 ) branches off with the air-fuel mixture. Furnace installation according to one of the preceding claims, characterized in that in the pilot combustion chamber ( 27 ) resulting flue gas into the combustion chamber ( 2 ) is derivable. Furnace installation according to one of the preceding claims, characterized in that a catalyst for flue gas cleaning is provided. Furnace installation according to one of the preceding claims, characterized in that transport means for transporting a strand ( 4 ), in particular a Stranguss rod or a bolt, in particular an aluminum strand through the combustion chamber ( 2 ) are provided. Plant for treating strands ( 4 ), in particular extruded rods or bolts, in particular of aluminum, comprising a furnace installation ( 1 ) according to one of the preceding claims, which is arranged upstream of a shearing and / or pressing arrangement.