WO2012123377A1

WO2012123377A1 - Melt pouring method and production unit

Info

Publication number: WO2012123377A1
Application number: PCT/EP2012/054170
Authority: WO
Inventors: Johannes Beuse; Frank Rheker
Original assignee: L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude; Air Liquide Deutschland G.M.B.H
Priority date: 2011-03-14
Filing date: 2012-03-09
Publication date: 2012-09-20
Also published as: DE102011013950A1

Abstract

Method of pouring a melt stream from an outflow opening of a melting furnace (19) and melt production unit whereby one burner apparatus (1) is used to generate a first flame (2.1) and a second flame (2.2) forming an angle (18) of at least 5° between them and whereby the first flame (2.1) is directed at an outflow opening (20) of the melting furnace (19) and whereby the second flame (2.2) is directed at a melt stream flowing from said outflow opening (20).

Description

MELT POURING METHOD AND PRODUCTION UNIT

The present invention relates to a melt pouring method adapted for heating an outflow opening of a furnace and a melt stream flowing therefrom, and in particular for heating an outflow opening from an enamel furnace and a stream of liquid enamel flowing therefom, as well as to a corresponding melt production unit.

To produce enamel, a mixture comprising glass-forming oxides is usually finely ground and melted in an enamel furnace. The mixture is firstly preheated in the enamel furnace using a first main burner and melted using a second main burner. The molten mixture flows through an outflow opening out of the enamel furnace and as a melt stream along a wall arranged under the outflow opening into a water bath. In order to heat the outflow opening and the wall, at least one burner is provided on the side opposite the outflow opening of the enamel furnace, the flame of which is directed at the outflow opening. It has in practice been found that a single burner is not sufficient for keeping the melt stream mixture in the molten state until it enters into the water bath. It has therefore proved to be efficient to direct a second burner at the wall under the outflow opening and therewith to heat the stream of the molten mixture further. These burners are known in the art as "door burners" and are generally operated using air as the oxidant for combustion.

It has now been found that the known door burners do not necessarily provide sufficient energy for keeping the molten mixture at a suitably high temperature or even in the liquid state. In order to sustain smooth operation of the enamel furnace, it is furthermore necessary to regularly clean the outflow opening mechanically. In this context, the arrangement of two door burners lying opposite the outflow opening of the enamel furnace is unfavourable, since at least one door burner has to be switched off to gain access to the outflow opening for cleaning. Similar problems arise with respect to other furnaces having and outflow opening from which a melt stream is poured. It is an object of the present invention, therefore, to solve at least some of the problems outlined with respect to the prior art. In particular, the intention is to provide a melt pouring method and a melt production unit which make it possible to provide high heating power at a plurality of adjacent locations.

The object is achieved by a method and a production unit as per the features in the independent claims. Further advantageous embodiments of the invention are defined in the dependent claims. It should be pointed out that the features given individually in the dependent claims can be combined with one another in any desired, technologically meaningful manner and define further configurations of the invention. In addition, the features indicated in the claims are described and explained in more detail in the description, presenting further preferred configurations of the invention.

The object is more specifically achieved by a method pouring a melt stream from an outflow opening of a melting furnace whereby a burner apparatus is used to combust fuel with an oxidant so as to generate at least a first flame and a second flame separate from the first flame, wherein the first flame and the second flame diverge and form an angle of at least 5° between them, whereby the first flame is directed substantially at the outflow opening and whereby the second flame is directed substantially at the melt stream downstream of the outflow opening. The burner apparatus used in said method preferably comprises:

at least one fuel feed having a discharge side,

an oxidant feed which surrounds the at least one fuel feed and has a discharge opening.

A nozzle portion having at least a first outlet opening for generating the first flame and a second outlet opening for generating the second flame is formed on the discharge side of the at least one fuel feed. The first outlet opening lies substantially in a first outlet plane and the second outlet opening lies substantially in a second outlet plane. The first outlet plane and the second outlet plane include a first angle of at least 5°. The burner apparatus generally extends from a supply side to a flame side, with a fuel being guided from the supply side to the flame side in at least one, preferably precisely one, fuel feed. The fuel is guided here from the so-called admission side on the supply side to the discharge side. The oxidant which is required for the combustion of the fuel is guided from the supply side to the flame side in the oxidant feed. The opening in the oxidant feed through which the oxidant leaves the oxidant feed is referred to as the discharge opening.

According to the invention, the oxidant feed preferably surrounds the fuel feed, this therefore meaning that the fuel feed is arranged in the oxidant feed. In order to space the at least one fuel feed apart in the oxidant feed, spacers can be provided on the outer side of the fuel feed and/or the inner side of the oxidant feed.

The nozzle portion is formed on the discharge side of the at least one fuel feed and the fuel therefore likewise flows through it during operation. The region in which a flow parameter of the fuel in the fuel feed changes is designated in particular as the nozzle portion. This change can be in particular a reduction in the flow diameter and/or a change in direction of the flow. Here, the region in which the fuel leaves the nozzle portion and therefore the burner is designated as the outlet opening. Downstream of the outlet opening, the fuel mingles with the oxidant and can undergo an exothermic reaction therewith.

According to the invention, each outlet opening can be assigned a separate fuel feed. However, it is preferable for precisely one fuel feed to be present and for the outlet openings to be formed in precisely one component of the nozzle portion. A boundary of the outlet opening determines the outlet plane. If the boundary does not lie in one plane, the outlet plane is preferably to be understood to mean an equalization plane which tangentially touches the border in at least two points, the distance between the border and the equalization plane at all points of the border being minimal. Furthermore, an outlet plane is defined with preference in such a way that it is normal to the respective main direction of flow of the jet of fuel which has left through the outlet opening in each case, i.e. to the main direction of flow of the fuel which is generated by the nozzle portion with the outlet opening. The burner has at least two outlet planes with at least one outlet opening being formed in each one of said outlet planes. The at least two outlet planes are aligned with respect to one another in such a way that they intersect at a first angle of at least 5°, the acute angle being taken as a reference. It is not necessary for the first angle to coincide with the angle included by the two corresponding flames, but this is preferred.

By virtue of the configuration according to the invention of the nozzle portion, two jets of fuel which include an angle of preferably greater than 5° are formed as the fuel flows through the outlet openings of the fuel feed. The exothermic reaction between the fuel in the two jets and the oxidant which surrounds the fuel substantially after it has left the outlet opening of the oxidant feed forms two separate flames, which likewise include an angle of preferably more than 5° with one another. In this context, a flame is understood to mean the region in which the fuel undergoes an exothermic reaction with the oxidant and from which light from the visible spectral range is emitted. Two separate flames is therefore to be understood to mean that there are two separate, unrelated regions in which the fuel undergoes an exothermic reaction with the oxidant and which each emit light from the visible spectral range.

According to the invention, it is therefore possible to heat two areas arranged separately from one another using only one burner. Compared to solutions known from the prior art, all that is additionally needed is a delivery system for the fuel, the oxidant and for control lines to the single burner. Further burners are no longer required if adjacent areas arranged separately from one another are to be heated.

According to a preferred embodiment of the invention, the nozzle portion is connected releasably to the at least one fuel feed. By way of example, a releasable connection can be realized by a thread, where provision is made of a split pin bore with which the nozzle portion can be fastened to the fuel feed in a predefinable position. It is thereby readily possible to quickly exchange the nozzle portion, it being possible to provide differently designed nozzle portions, such that, for example, the number of flames or the flame distribution is changed by exchanging the nozzle portion. This is particularly simple given precisely one fuel feed in particular.

According to a further preferred embodiment of the invention, a cross-sectional area of the first outlet opening differs from a cross-sectional area of the second outlet opening. In this case, cross-sectional area means in particular the area defined by the boundary of the outlet opening. The cross-sectional areas of the different outlet openings can therefore differ inter alia in their shape and/or in their area size. The cross-sectional area substantially determines the shape, the size and/or the intensity of a flame at least compared to the further flames. Therefore, it is possible to set a different heating power of the two flames by virtue of the ratio between the cross-sectional area of the first outlet opening and the cross-sectional area of the second outlet opening.

In a development of the invention, it is proposed that precisely one fuel feed is provided, wherein the nozzle portion has a conical outer surface. The outer surface of the nozzle portion means in particular the surface in which the outlet openings are arranged. A conical outer surface is particularly easy to produce using simple manufacturing measures. The outlet plane of the outlet openings in the conical outer surface is the tangential surface on the conical outer surface, which contains the central point of the outlet opening and which is therefore identical to the equalization plane described above.

Another development of the invention is characterized in that the first outlet opening and the second outlet opening are in the form of bore openings of bores. With bores, it is possible to introduce particularly simple structures into the nozzle portion, with which the fuel can be guided. In this context, it is particularly preferable for the bores to have bore axes and for the bore axes to include a second angle of 20° to 40°, preferably of 25° to 35°. The bores therefore form ducts by which the original direction of flow of the fuel in the fuel feed is diverted into the direction of flow of the emerging fuel. The second angle therefore preferably corresponds to the angle included by the flames during operation. By setting the second angle, it is therefore possible to adapt the flame distribution to the predefined operating conditions.

A cross section of the outlet opening of the oxidant feed preferably has a circular cross section. In a particularly preferred embodiment of the invention, the cross section of the outlet opening of the oxidant feed has a first length in a first direction and a second length in a second direction, wherein the second direction is orthogonal to the first direction and the quotient of the first length and the second length is not equal to 1, preferably greater than 1.2. This means in particular that the cross section of the outlet opening of the oxidant feed is not circular. By way of example, the cross section is elliptical or oval. Cross section means a section through the burner which is orthogonal to the longitudinal axis of the burner and therefore substantially also orthogonal to the fuel feed and the oxidant feed. It is preferable for the first length to lie in the plane in which the angle included by the flames lies, if two flames are formed. This should ensure that the oxidant is conducted with preference into the region of the flames.

According to the invention, it is preferable for the burner to have an apparatus for detecting the flames. The apparatus for detecting the flames is preferably connected to a control device, such that the operation of the burner according to the invention can be monitored from a control station. In this context, it is also advantageous for the burner to have an automatic ignition apparatus.

According to a further aspect of the invention, the method comprises at least the following steps:

- oxidant is guided through the oxidant feed,

- fuel is guided in the at least one fuel feed, which is surrounded by the oxidant feed, - the fuel is guided through at least the first outlet opening and the second outlet opening out of the fuel feed in order to generate at least two jets of fuel, such that at least the first flame and the second flame separate from the first flame are formed, wherein the first flame and the second flame include an angle, called third angle of at least 5°. The first flame and the second flame preferably include an angle between 20° and 40°. However, the two flames can also include a third angle of up to 90°.

The two jets of fuel react with the oxidant which typically surrounds them and therefore form the at least two flames in an exothermic reaction. Via operating parameters such as the volumetric flow rate and/or pressure of the oxidant and of the fuel and also the ratios thereof in relation to one another, it is possible to change parameters of the at least two flames. If the pressure of the fuel is increased, for example, it is possible for the flame to be lengthened.

It is particularly advantageous if the oxidant comprises at least 30% by volume, particularly preferably at least 50% by volume and very particularly preferably at least 90% by volume oxygen. An oxidant of this type is provided, for example, by oxygen-enriched air or by pure oxygen. Using an oxidant with a high oxygen content, it is possible to generate a very high flame temperature during the exothermic reaction with the fuel. It is therefore possible to generate at least two separate flames which each have a very high flame temperature and heat areas arranged separately from one another more effectively. Furthermore, it is advantageous if the fuel is a combustible gas mixture, natural gas, liquid gas, biogas, acetylene, propane or hydrogen.

Yet another aspect of the invention proposes a melt production unit and in particular an enamel production unit, comprising a furnace having an outflow opening for a melt, such as liquid enamel, a wall which is located under the outflow opening and a burner as described above, wherein the burner apparatus is set up in such a way that, during operation, a flame, "first flame" is directed at the outflow opening and a further flame, "second flame" is directed at the wall underneath the outflow opening. During operation, the melt, which is generally heated by at least one main burner of the furnace, passes through the outflow opening, the melt flowing through the outflow opening and the melt stream then flowing down along the wall being heated by the burner apparatus.

The furnace having the outflow opening may be a melting furnace in which a melt is generated by melting solid material or another furnace containing a melt such as a melt holding furnace or a melt transfer furnace.

A flame, first flame and/or second flame, which is generated according to the invention preferably has a length of 40 cm [centimetre] to 100 cm, particularly preferably of 50 cm to 90 cm. It is preferable for the burner apparatus to be operated with a heating power of 100 kW [kilowatt] to 200 kW, preferably of 130 kW to 170 kW.

In order to make it possible to rapidly cool the fuel feed after the burner apparatus has been switched off, cooling air is preferably fed to the burner apparatus.

The details and advantages which are disclosed for the production unit according to the invention can be transferred and applied to the method according to the invention, and vice versa.

The invention and the technical field will be explained in more detail below on the basis of the figures. The figures show particularly preferred exemplary embodiments, to which the invention is however not restricted. It should be pointed out in particular that the figures, and in particular the illustrated dimensional relationships, are merely schematic. Schematically: Figure 1 : shows a burner apparatus adapted for use in the invention, Figure 2: shows a nozzle portion of a burner apparatus adapted for use in the invention in a sectional illustration,

Figure 3 : shows a view from below of the nozzle portion shown in Figure 2,

Figure 4: shows the nozzle portion shown in Figure 2,

Figure 5 : shows a partial schematic view of an enamel production unit according to the invention,

Figure 6: shows a cross section through the burner apparatus shown in Figure 1.

Figure 1 schematically shows a burner apparatus 1 comprising a fuel feed 3 and an oxidant feed 5 which surrounds the fuel feed 3 for generating two flames 2.1, 2.2. The flames 2.1, 2.2 include a third angle 18. The fuel feed 3 has a discharge side 4, on which a nozzle portion 7 is fastened. The oxidant feed 5 has a discharge opening 6 on the side of the burner apparatus 1 on which the flames 2.1, 2.2 form. At least in the region of the discharge side of the fuel feed 3, the oxidant feed 5 has a cross section 15, which is shown in Figure 6.

During operation, a fuel is conducted through the fuel feed 3 and an oxidant is conducted through the oxidant feed 5. The nozzle portion 7, through which the fuel leaves the fuel feed 3 and which is described in more detail with reference to Figures 2 to 4, is designed in such a way that two jets of fuel form, such that two flames 2 which include a third angle 18 form during an exothermic reaction between the fuel and the oxidant.

Figures 2 to 4 show a nozzle portion 7, which is shown in a sectional illustration in Figures 2 and 4 and is shown in a view from below in Figure 3. The nozzle portion 7 comprises a conical outer surface 24, in which a first outlet opening 8.1 and a second outlet opening 8.2 are formed. The first outlet opening 8.1 and the second outlet opening 8.2 are formed by a bore 12 having a bore opening 1 1. The first outlet opening 8.1 lies in a first outlet plane 9.1, the first outlet plane 9.1 lying tangentially against the first outlet opening 8.1. The first outlet plane 9.1 is, however, also parallel to an imaginary equalization plane through the outlet opening 8.1. The second outlet opening 8.2 lies accordingly in a second outlet plane 9.2. The first outlet plane and the second outlet plane intersect with a first angle 10.

The bores 12 have a bore axis 13, which intersects with a second angle 14. The second angle 14 is of a similar size to the third angle 18 included by the flames 2 during operation.

Figure 5 schematically shows the use of a burner apparatus 1 with an enamel furnace 19. The burner apparatus 1 comprises at least one fuel feed and one oxidant feed 5. A melt from the enamel furnace 19 emerges through an outflow opening 20 and flows as a melt stream down along a wall 21. The region of the outflow opening 20 and the wall 21 are heated by the burner apparatus 1 using two separate flames 2, which include a third angle 18. By using the burner apparatus 1 according to the invention, it is therefore no longer necessary to install and operate two separate burner apparatus. It is merely necessary to provide a supply line to the one burner apparatus 1 according to the invention. When only one burner apparatus 1 is thus used, it is possible to mechanically clean the outflow opening 20 during operation, since the holding devices and delivery lines to an otherwise required second burner are not present in the vicinity of the outflow opening 20.

Figure 6 schematically shows a cross section through the burner apparatus shown in Figure 1. The cross section of the fuel feed 3 is circular, whereas the cross section 15 of the oxidant feed is elliptical. The cross section 15 of the oxidant feed therefore has a first length 22 in a first direction 16 which differs from a second length 23 in a second direction 17. As a result of such a cross section of the burner apparatus 1, oxidant is preferably distributed in the plane in which the two flames 2.1, 2.2 include the third angle 18. With the burner apparatus 1, it is possible to dispense with the installation of a plurality of burner apparatus for heating two adjacent locations. In addition, the region at which flames are directed is better accessible for maintenance work.

List of reference numerals

1 Burner apparatus

2 Flame

3 Fuel feed

4 Discharge side

5 Oxidant feed

6 Discharge opening

7 Nozzle portion

8.1 First outlet opening

8.2 Second outlet opening

9.1 First outlet plane

9.2 Second outlet plane

10 First angle

11 Bore opening

12 Bore

13 Bore axis

14 Second angle

15 Cross section

16 First direction

17 Second direction

18 Third angle

19 Enamel furnace

20 Outflow opening

21 Wall

22 First length

23 Second length

24 Outer surface

Claims

A method of pouring a melt stream from an outflow opening (20) of a

melting furnace whereby a burner apparatus (1) is used to combust fuel with an oxidant so as to generate at least a first flame (2.1) and a second flame (2.2) separate from the first flame (2.1), wherein the first flame (2.1) and the second flame (2.2) diverge and form an angle (18) of at least 5° between them, whereby the first flame (2.1) is directed substantially at the outflow opening and whereby the second flame (2.2) is directed substantially at the melt stream downstream of the outflow opening.

Method of claim 1, whereby the burner apparatus (1) comprises at least one fuel feed (3) having a discharge side (4), an oxidant feed (5) which surrounds the at least one fuel feed (3) and has a discharge opening (6), wherein

a nozzle portion (7) having at least a first outlet opening (8.1) for generating the first flame and a second outlet opening (8.2) for generating the second flame is formed on the discharge side (4) of the at least one fuel feed (3), wherein the first outlet opening (8.1) lies substantially in a first outlet plane (9.1) and the second outlet opening (8.2) lies substantially in a second outlet plane (9.2), and the first outlet plane (9.1) and the second outlet plane (9.2) include a first angle (10) of at least 5°.

Method according to claim 2, comprising at least the following steps:

- oxidant is guided through the oxidant feed (5),

- fuel is guided in the at least one fuel feed (3),

- the fuel is guided through at least the first outlet opening (8.1) and the second outlet opening (8.2) out of the fuel feed (3) in order to generate at least two jets of fuel, such that at least the first flame (2.1) and the second flame (2.2) separate from the first flame (2.1) are formed. Method according to any one of the preceding claims, whereby the first flame (2.1) and the second flame (2.2) provide different heating power.

Method according to any one of the preceding claims, wherein the oxidant comprises at least 30% by volume oxygen.

Method according to any one of the preceding claims, wherein the fuel is natural gas.

Method according to any one of the preceding claims, whereby the furnace

(19) is an enamel furnace

Melt production unit comprising a furnace (19) having an outflow opening

(20) for a melt, a wall (21) located under the outflow opening (20) and a burner apparatus (1) for generating at least a first flame (2.1) and a second flame (2.2) separate from the first flame, so that the first flame (2.1) and the second flame (2.2) diverge and form an angle (18) of at least 5° between them, wherein the burner apparatus (1) is set up in such a way that, during operation of the melt production unit, the first flame (2.1) is directed at the outflow opening (20) and the second flame (2.2) is directed at the wall (21) underneath the outflow opening (20).

Melt production unit, whereby the burner apparatus comprises:

at least one fuel feed (3) having a discharge side (4),

an oxidant feed (5) which surrounds the at least one fuel feed (3) and has a discharge opening (6), wherein

Melt production unit according to claim 9, wherein the nozzle portion (7) of the burner apparatus (1) is connected releasably to the at least one fuel feed (3).

Melt production unit according to claims 9 or 10, wherein a cross-sectional area of the first outlet opening (8.1) differs from a cross-sectional area of the second outlet opening (8.2).

Melt production unit according to any one of claims 9 to 11, wherein the nozzle portion (7) has a conical outer surface.

Melt production unit according to any one of claims 9 to 12, wherein at least the first outlet opening (8.1) and the second outlet opening (8.2) are in the form of bore openings (11) of bores (12).

Melt production unit according to any one of claims 9 to 13, wherein the bores (12) have bore axes (13) and the bore axes (13) include a second angle (14) of 20° to 40°.

Use of a melt production unit according to any one of claims 8 to 14, in the method of either one of claims 1 to 7.