DE102007005256A1 - Burner for e.g. hearth-type furnace for heating and melting of glass, has nozzle equipped with supply for primary oxidizing agent and another supply for secondary oxidizing agent equipped with unit for changing passage area of both supplies - Google Patents

Abstract

The burner (1) has a burner nozzle (2) discharging into a treatment space (4) via an opening (3) of a burner receptacle (5). The burner nozzle is equipped with a supply (11) for a primary oxidizing agent and another supply for a secondary oxidizing agent, where the latter supply is equipped with an unit for changing a passage area of both the supplies. The nozzle is axially adjustably formed in relation to the burner receptacle and has a fuel supply (9). An independent claim is also included for a method for introducing gaseous fuels into a treatment space.

Description

The The invention relates to a burner with a through an opening a burner receptacle opening into a treatment room Burner nozzle with at least one fuel supply and at least one supply for an oxidizing agent equipped.

such Burners are known. So come in the firing of industrial furnaces for heating and / or melting glass, ceramics or Metals burners are used, in addition to a mostly liquid or gaseous fuel air or pure oxygen is injected as an oxidizing agent. The burners are included mounted in a burner receptacle, for example in a in the Wall of the thermal treatment room arranged burner stone or a metallic burner tube.

Among the advantages in the use of pure oxygen as the oxidant is to be counted upon combustion, a substantially increased melting performance due to the higher thermal radiation and due to the higher energy efficiency, continued low NO _x emissions and low exhaust gas volumes. Advantages of air burners, on the other hand, are lower raw material costs and a high gas flow with inert nitrogen within the treatment space, which is advantageous on a case-by-case basis. Accordingly, it is recommended to use the high thermal efficiency of fuel-oxygen burners during a heating and / or melting phase, for example of metals or glass. In contrast, in the subsequent holding phase, in which only a relatively small thermal power is required, a firing of the treatment chamber with fuel-air burners beneficial.

In order to exploit the advantages of both operating modes, burners have already been described in which it is possible to switch between oxygen-fuel operation and air-fuel operation during use. So is out of the DE 100 46 569 A1 a burner is known in which a central supply line for fuel and - coaxially thereto and to each other - supply lines for two oxidants, namely a supply line for pure oxygen and a supply line for air, is provided. By switching on and off of the respective oxidant line can be switched at will from the oxygen mode in the air mode, without the need for different, specified for the respective oxidant burner. A disadvantage of this known oxygen-air burner, however, is that due to the unchangeable burner geometry very different outflow velocities of the oxidant must be realized when using air or oxygen. Since the stability and geometry of the flame are decisively influenced by the outflow velocity, the burner can only be stabilized in a very limited range of the ratio of air to oxygen or can be optimally driven for the respective treatment.

From the DE 101 56 376 A1 is a burner known that can be driven both with pure oxygen, with air and with air and oxygen in mixed operation. In this article, an oxygen burner is housed in an air supply, which is at the same time an adjustable swirler, preferably of the "Movable Block" type preceded .. In addition to the adjustability of the pulse streams of fuel, oxygen and air can and must with this burner in addition Swirl strength can be set between S = 0 (no swirl) and S = 2 (supercritical swirl) Due to the variable swirl strength of the air, the flame length and shape as well as the control range can be changed and so the flame at least in a wide range of different mixing ratios of air and However, this is all the more incomplete as the oxygen content in the oxidant decreases, in which case the flow rate in the oxidant supply lines must be increased to compensate for the higher level of incombustible gases, but above a certain limit to flame instability f leads.

task The invention is therefore to provide a burner which is a continuous Adjustability of the oxygen content of the supplied oxidizing agent at the same time high stability of the flame or the thermal Conditions in the treatment room allowed.

Solved This object is in a burner of the type mentioned and Purpose in that the supply for the oxidizing agent with means for changing the flow cross-section the feeder is equipped.

In contrast to the oxygen-air burners according to the prior art, according to the invention, the inflow through the oxidant feed is influenced by a change in its free flow cross-section. Thus, the volume flow through the oxidant line can be increased or decreased, without necessarily also the flow velocity in the respective oxidant supply is changed. Even with a constant reduction of the oxygen content in the oxidant, such as a gradual change from the operating mode "pure oxygen" to the "air" mode can thus be dispensed with, despite the reduction of the oxygen content of almost 100% to 20%, the exit velocity of the Oxidizing agent to increase greatly with constant burner performance. As a result, in particular the formation of a stable flame or ensures stable combustion conditions in the treatment room even at different oxygen concentrations in the oxidant. A swirl adjustment is not required for flame stabilization in the burner according to the invention, but may additionally be provided.

A advantageous development of the invention provides that the burner nozzle with at least one feeder for primary Oxidizing agent and at least one feed for a secondary oxidizer is equipped, wherein at least the feeder for secondary Oxidizing agent with means for changing the flow cross-section equipped. In this embodiment contributes the primary oxidant is the base load for the burning. The amount of secondary oxidant Accordingly, in particular depending on the ratio be changed from air and oxygen. primary and secondary oxidant can thereby a different or even the same chemical composition to have.

Prefers is the flow cross-section of at least one feed for primary and / or secondary oxidant continuously changeable and allows it a continuous adjustment of the oxygen content in the oxidant.

A advantageous development of the invention provides that the burner nozzle formed axially displaceable relative to the burner holder is. For example, with "burner recording" a burner brick or the metal shell of a burner tube meant. Change by moving the burner nozzle geometry of the flame and the flow conditions in the treatment room. Due to the displaceability of the burner nozzle opposite the burner block or the metal jacket of the burner tube Thus, an additional parameter is obtained to the To optimize conditions in the treatment room.

In a again advantageous embodiment of the invention Brenners is operatively connected by an axial movement closing mechanism or at least one supply for oxidizing agent opened and / or closed. The free flow cross section The oxidant supply is thus by the axial Controlled displacement of the burner nozzle.

A Particularly preferred embodiment is characterized by the realized the following structure: The axially movable burner nozzle is equipped with a burner head attached to his Treatment room facing side is conically formed. To this conically shaped burner head corresponds to a recess in the burner holder, which is also conical and that such that at axial displacement of the burner nozzle between the burner head and the conical recess in the burner holder an annular gap opens, expands and / or closes. The annular gap is in the flow path of the feeder integrated for secondary oxidant. Thereby manages the stream of secondary oxidant in particular to be controlled by the variation of the annular gap diameter.

The at least one primary oxidant feed and / or the at least one feeder for secondary Oxidizing agent may be advantageous with a supply line for Oxygen and / or fluidly connected to an air supply line are. Here are several possibilities conceivable: On the one hand, those of feeders for primary or secondary oxidant fluidically separated from each other with the respective supply lines for oxygen or air, or it finds one first Mixing of air and oxygen to a gas mixture instead, the then both in the feeder for primary as well as in the feeder for secondary oxidant is introduced.

Around in particular a flameless combustion with outside circulating To allow combustion gas, it is advantageous that the air supply line fluidly connected to the interior of the treatment room is. At the same time as needed for combustion Oxygen is recirculated so exhaust gas from the treatment room, through the lowered the temperature in the combustion or reaction zone and at the same time a more even temperature distribution is effected in the treatment room.

A particularly maintenance-friendly embodiment of the invention Brenners provides that the supply line for oxygen and lead the supply line for air into a mixing chamber, that with both the feeder (s) for primary Oxidizing agent as well as with the / the supply / s for secondary oxidant fluidly connected is. Oxygen and air thus become a homogeneous gas mixture mixed and then the or the Oxidationsmittelzuführung / s fed.

Appropriately, the burner nozzle is associated with an automatic control by means of which the supply of air and / or oxygen in dependence on one or more physical parameters in the treatment room is adjustable. As a parameter, for example, the temperature in the treatment chamber, the temperature of the furnace wall, the oxygen concentration of the supplied oxidant, a pollutant concentration in the exhaust gas, for example, NO _x , or the state of a material to be melted detected and from the detected th data set according to a predetermined, calculated or empirically determined program the required oxygen supply.

The The object of the invention is also achieved by a method solved with the features of claim 11.

at a method for introducing fuel gases into a treatment room, in which a fuel through a fuel supply and an oxidizing agent by at least one oxidant supply is introduced through into the treatment room is, as Oxidant oxygen and air in a given or during implementing the changing relationship, depending on the ratio of air and oxygen the amount of oxidant introduced by change the free flow cross-section of at least one of the Oxidationsmittelzuführungen will be changed. The change of the flow cross section allows the influx of different gas volumes at constant or only slightly changed outflow velocity. As a result, in particular different oxygen concentrations of the oxidizing agent at different mixing ratios taken into account by oxygen and air. The invention Process in which preferably the inventive Burner is used, allows oxygen and Air in any ratio to each other, so with an oxygen content between 20% and 100% in the treatment room enter and yet a stable combustion in the treatment room to maintain.

Flame-less combustion preferably takes place in the treatment chamber. In "flameless combustion", also referred to as "mild" or "dilute" combustion, the furnace gas recirculates in the treatment space and causes a more even temperature distribution throughout the treatment space while reducing the temperature in the area of the burner nozzle Combustion with flame a significant reduction in NO _x values.The principle of flameless combustion is known per se and is used for example in the EP 0 463 218 A1 described.

Based of the drawings, an embodiment of the invention be explained in more detail. In schematic views demonstrate:

1 A burner according to the invention in a first setting position in a longitudinal section and

2 : The burner off 1 in a second setting position with closed annular gap.

In the 1 and 2 are the same features provided with the same reference numerals. The burner shown in the drawings 1 includes a burner nozzle 2 passing through the opening 3 one in the wall of a metallurgical treatment room 4 taken in burner brick 5 opens. Alternatively or in addition to the burner stone 5 can the burner nozzle 2 for example, be arranged in the metal shell of a burner tube, which opens into the treatment room. Without limitation of generality, the arrangement of the burner nozzle will be described below 2 in a burner stone 5 closer look. The burner nozzle 2 is in a burner housing 6 arranged, the solid and at least largely gas-tight with the burner block 5 connected is. The burner nozzle 2 is axially displaceable in the burner housing 6 recorded, with the displacement of the burner nozzle 2 in a manner not shown here, either by means of a servomotor or mechanically, for example via a manual handwheel, or hydraulically or pneumatically.

The burner nozzle 2 includes a burner head 7 , of the holders not shown here on an axis 8th coaxial with the circular cylindrical opening 3 of the burner brick 5 is held. Central through the burner head 7 and the burner housing 6 extends through a fuel supply 9 , which at their exit from the nozzle 10 opposite end is connected in a manner not shown here to a supply line for gaseous or liquid fuel. Coaxial to the fuel supply 9 extends through the burner head 7 through a feeder 11 for primary oxidant, also at the nozzle exit 10 opens. At the nozzle exit 10 opposite end face 13 of the burner head 7 the feeder flows 11 in contrast, in the interior 14 of the burner housing 6 one.

The burner housing 6 is with one or more, in the embodiment with two, leads 15 . 16 equipped for oxidizing agent. In the feeders, which may be configured as a flange or as a screw, it is in the embodiment to a supply line 15 for oxygen and a supply line 16 for air. Of course, in the context of the invention by the leads 15 . 16 to other oxidants, in particular oxidants with different amounts of oxygen, in the interior 14 of the burner housing 6 be initiated. The influx of oxygen or air through the supply lines 15 . 16 can be adjusted or regulated independently by means of valves not shown here. In the embodiment, therefore, both leads open 15 . 16 for air and oxygen in the interior 14 one; The interior 14 acts as a mixing chamber in which mix air and oxygen to form a homogeneous gas mixture whose acid content is determined by the amounts of oxygen supplied or the air supplied. However, it is also possible in the context of the invention, the supply line 15 for oxygen via a conduit with the feeder 11 to connect for primary oxidant and thus the gas flows of oxygen and air to the nozzle exit 10 to keep away from each other.

At his to the nozzle exit 10 pointing end face, the burner head 7 a conically shaped front section 17 on. With the same angle as the conical front section 17 of the burner head 7 extends in the burner stone 5 (or in the case of the burner nozzle 2 surrounding burner tube in the metal jacket), coaxial with the opening 3 a likewise conical recess 18 , In the in 1 shown positioning position is the burner nozzle 2 spaced from the burner stone 5 or the metal shell, wherein between the conical front portion 17 of the burner head 7 and the conical recess 18 in the burner stone 5 an annular gap 20 extends. The annular gap 20 is with the interior 14 of the burner housing 6 fluidly connected and thus allows the supply of oxidant from the interior 14 as a secondary oxidant.

In the in 2 shown positioning position is the burner nozzle 2 with the conical front section 17 in the conical recess 18 of the burner brick 5 move into it, and the annular gap 20 is closed. In this position you are fed with the supply of oxidizing agent exclusively via the feeder 11 for primary oxidant.

When using a servomotor to move the burner nozzle 2 this can also be in data connection with an automatic regulation not shown here, which is the feed of the burner nozzle 2 depending on certain measured parameters, for example the temperature or the concentration of certain gases in the treatment room 4 or the condition of one in the treatment room 4 present Behandlungsguts, regulates.

When operating the burner 1 is about the fuel supply 9 a liquid or gaseous fuel, such as natural gas, in the treatment room 4 initiated. Will the burner 1 operated as a pure oxygen burner, the burner is in the setting position, as in 2 is shown. The oxygen used as the oxidizing agent is supplied via the supply line 15 for oxygen in the interior 14 initiated and passes from there via the feeder 11 for primary oxidant in the treatment room 4 , The supply line 16 Air is closed during this time. In this operating mode as a pure oxygen burner has the burner 1 a high melting capacity with low exhaust gas volumes.

If it is desired during the course of the treatment to switch to mixed air-oxygen mode or air mode, for example after completing a reflow process and starting a holding phase, air is supplied via the supply line 16 in the interior 14 initiated; at the same time the supply of the amount of oxygen via the supply line 15 throttled according to the stoichiometric ratios. Shall be over in the treatment room 4 introduced amount of fuel defined capacity of the burner 1 kept constant, a correspondingly larger volume must be supplied due to the high nitrogen content of the air. For this purpose, the burner nozzle 2 in the direction of the burner stone 5 moved away, for example, in the 1 shown position, wherein the annular gap 20 opens. Due to the enlarged outlet cross section can now a higher volume of oxidant in the treatment room 4 be introduced without the exit velocity of the oxidant at the nozzle exit 10 must be significantly increased. The lower the oxygen content in the oxidizing agent, the larger the outlet cross-section of the annular gap becomes 18 selected, that is, the farther the conical front section is located 17 from the conical recess 18 of the burner brick 5 away. In this way, the free flow cross section through the annular gap 18 continuously changed and can be adapted to the respective requirements. This will be inside the treatment room 4 ensures stable combustion conditions.

In the operating mode as an air burner is the burner 1 especially for use in flameless combustion in the treatment room 4 suitable. The flameless combustion in the treatment room leads to a lowering of the temperatures in the area of the nozzle outlet 10 and overall a reduction in the NO _x values in the exhaust gas. For this purpose, the supply line 16 for air also with the treatment room 4 be in flow communication, so that during the treatment exhaust gas from the treatment room 4 taken and over the supply line 15 back to the treatment room 4 can be fed (so-called "external recirculation").

The burner according to the invention 1 can be used both for hearth furnaces and for rotary furnaces and is particularly suitable for melting non-ferrous metals or glass but also for heating furnaces of any kind. Without impairing the flame stability, the oxygen content in the oxidizing agent can be varied between 20% by volume and 100% by volume. It combines the positive qualities of air burners with those of pure oxygen burners, including the possibility to flam without combustion and is easy to install in existing stoves. Its construction makes it particularly robust and low maintenance. Particularly in the metal industry, the burner according to the invention makes possible a higher productivity, lower energy consumption and more flexible methods of operation, with at the same time significantly lower pollutant emissions.

1

burner

2

burner

3

opening

4

treatment room

5

Brennerstein

6

burner housing

7

burner head

8th

axis

9

fuel supply

10

nozzle exit

11

feed for primary oxidant

12

13

front

14

inner space

15

supply for oxygen

16

supply for air

17

conical front section

18

conical recess

19

20

annular gap

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 10046569 A1 [0004]
• - DE 10156376 A1 [0005]
• EP 0463218 A1 [0020]

Claims (12)

Burner with one through an opening ( 3 ) of a burner recording ( 5 ) into a treatment room ( 4 ) merging burner nozzle ( 2 ) provided with at least one fuel supply ( 9 ) and at least one feeder ( 11 . 20 ) is equipped for an oxidizing agent, characterized in that the supply ( 11 . 20 ) for the oxidant with agents ( 17 . 18 ) for changing the flow cross-section of the feeder ( 11 . 20 ) is equipped. Burner according to claim 1, characterized in that the burner nozzle ( 2 ) with at least one feeder ( 11 ) for primary oxidant and at least one feed ( 20 ) is equipped for a secondary oxidant, wherein at least the feed ( 20 ) for secondary oxidant with agents ( 17 . 18 ) is equipped for changing the flow cross-section. Burner according to claim 1 or 2, characterized in that the flow cross-section of at least one feed ( 11 . 20 ) is continuously variable for primary and / or secondary oxidant. Burner according to one of the preceding claims, characterized in that the burner nozzle ( 2 ) axially displaceable relative to the burner receptacle ( 5 ) is trained. Burner according to claim 4, characterized in that by a with the axial movement of the burner nozzle ( 2 ) operatively connected closing mechanism the at least one feed ( 20 ) can be opened and / or closed for oxidizing agent. Burner according to claim 5, characterized in that the burner nozzle ( 2 ) with a burner head ( 7 ) located at the treatment room ( 4 ) facing side is conically formed and with a conical recess ( 18 ) of the burner holder ( 5 ) corresponds in such a way that with axial displacement of the burner nozzle ( 2 ) between burner head ( 7 ) and the recess ( 18 ) of the burner holder ( 5 ) an annular gap ( 20 ) opens, extends and / or closes which annular gap ( 20 ) into the flow path of the feeder ( 20 ) is integrated for secondary oxidant. Burner according to one of the preceding claims, characterized in that the feeder ( 11 ) for primary oxidant and / or the feed ( 20 ) for secondary oxidant with a feed line ( 15 ) for oxygen and / or with an air supply line ( 16 ) is fluidly connected / are. Burner according to one of the preceding claims, characterized in that the air supply line ( 16 ) with the interior of the treatment room ( 4 ) is fluidly connected. Burner according to one of the preceding claims, characterized in that the supply line ( 15 ) for oxygen and the air supply ( 16 ) into a mixing chamber ( 14 ), which are connected to the feeder ( 11 ) for primary oxidant and with the feed ( 20 ) is fluidly connected to secondary oxidant. Burner according to one of the preceding claims, characterized in that the burner nozzle ( 2 ) is assigned an automatic control by means of which the supply of air and / or oxygen in dependence on physical parameters in the treatment room ( 4 ), such as temperature, oxygen content, etc. is adjustable. Method for introducing fuel gases into a treatment room ( 4 ), in which a fuel through a fuel supply ( 9 ) and an oxidizing agent by at least one oxidant supply ( 11 . 20 ) is introduced into the treatment space, characterized in that oxygen and air in a predetermined or during the introduction of changing ratio is used as the oxidizing agent, wherein depending on the ratio of air and oxygen, the amount of in the treatment room ( 4 ) introduced oxidizing agent by changing the free flow cross-section of at least one of the Oxidantmittelzuführungen ( 20 ) will be changed. Method according to claim 11, characterized in that in the treatment room ( 4 ) a flameless combustion takes place.