Low carbon dioxide emission centrifugal process for manufacturing mineral fibers

Abstract

The present invention relates to a method for manufacturing mineral fibers by an installation comprising an annular burner, the burner comprising a combustion chamber and a nozzle, the nozzle connecting the combustion chamber to the outside of the burner, a fiber-forming plate adapted for forming filaments of the thermoplastic material by centrifugation, the method comprising at least one step of injecting a first fluid into the combustion chamber at a first flow rate, the first fluid comprising a fuel, the fuel comprising dihydrogen, a volume fraction of dihydrogen in the first fluid being greater than 0.05. Fig 2

Description

Title of the invention: Process for manufacturing mineral fibers by low carbon dioxide emission centrifugation. Field of the invention

[0001] The present invention relates to a process for manufacturing mineral fibers by internal centrifugation and an installation adapted for implementing this process. The process can, in particular, be applied to the industrial manufacture of glass wool. Prior art

[0002] It is known to manufacture mineral wool by an internal centrifugation process. With reference to [Fig. 1], document FR305767 describes an installation 2 known for manufacturing mineral fibers 1 by internal centrifugation, comprising a fiber-spun plate 6, a basket 16, and a shaft 17 arranged along a principal axis X. The shaft 17 is configured to be driven in rotation by a motor (not shown). The shaft 17 is hollow, so as to form a conduit 18 into which molten thermoplastic material can flow. The thermoplastic material is preferably glass. The installation 2 is configured so that the principal axis X is vertical in a terrestrial frame of reference and the thermoplastic material can be poured into the conduit 18 to fall into the basket 16. The conduit 18 is fluidly connected to a molten thermoplastic material supply at one of its ends.Plate 6 and basket 16 are fixedly mounted at the other end of the tree by means of a tulip 19.

[0003] The plate 6 comprises a first annular wall 20 and a web 21. The first annular wall 20 is pierced by a plurality of orifices 7. The web 21 is arranged between the first annular wall 20 and the tulip 19. The web 21 forms an upper part of the plate 6. A diameter Da of the plate is defined as being equal to twice a radius Ra of the plate 6. The radius Ra is defined as the distance between the principal axis X and a point A of the first wall 20 furthest from the principal axis X.

[0004] The basket 16 comprises a second annular wall 22. The second annular wall 22 is pierced by a plurality of orifices. A diameter Dp of the basket 16 is defined as being equal to twice a radius Rp of the basket 16. The radius Rp is defined as the distance between the principal axis X and a point B of the second wall 22 furthest from the principal axis X. The basket is mounted inside the fiber-laying plate.

[0005] During the manufacture of mineral fibers 1 by the installation 2, the shaft 17, the fiber-forming plate 6, and the basket 16 are driven together in rotation about the main axis X. The molten thermoplastic material is poured into the conduit 18 of the shaft 17 from the thermoplastic material feed and flows into the conduit 18 up to basket 16. The material is projected onto the second annular wall 22 by centrifugation driven by the assembly of the shaft 17, the fiber-forming plate 6 and the basket 16. The material then flows into the plurality of orifices of the second annular wall 22 before being projected onto the first annular wall 20. The material then flows into the plurality of orifices 7 of the first annular wall 20 so as to form filaments 8 of the material.

[0006] When the material is projected onto the first annular wall 20, a reservoir of material is formed in the fiber-forming plate 6. This reservoir allows for the continuous feeding of the plurality of orifices 7 in the first wall 20 to form the filaments 8.

[0007] The installation 2 includes an annular burner 3. The annular burner 3 is configured to generate a drawing gas flow enabling the filaments 8 produced at the outlet of the orifices 8 of the first wall 20 to be drawn. The burner 3 has an axis of symmetry coinciding with the principal axis X of the shaft 17. The burner 3 has a gas outlet arranged above the first annular wall 20. The drawing gas flow exiting the burner 3 has a direction tangential to the first wall 20. The drawing gas flow heats both the first wall 20 and the filaments 8 that form at the outlet of the orifices 8 of the first wall 20. Under the action of the drawing gas flow, the filaments 8 are stretched, then break to form mineral fibers 1. The mineral fibers 1 are then collected under the plate 6.

[0008] With reference to document WO 03 / 069226, the drawing gas flow is produced by combustion in the annular burner 3. The annular burner 3 may include a combustion chamber 4 and a nozzle 5. The nozzle 5 connects the combustion chamber to the outside of the burner 3. The combustion chamber 4 is supplied with oxidizer and fuel. The combustion reaction is initiated in the combustion chamber. Methane is typically used as the fuel. Air is typically used as the oxidizer. The combustion reaction described above makes it possible both to maintain a drawing gas flow with a sufficient drawing temperature at the lips 11 of the nozzle 5, for example between 1100 °C and 1600 °C, and to maintain a sufficient gas flow rate to draw the filaments 8, for example between 5000 mV / hour and 8000 mV / hour.

[0009] However, the combustion reaction described above produces a very large quantity of carbon dioxide and can also produce nitrogen oxides, sulfur oxides, carbon monoxide, and hydrocarbons not consumed by the reaction. It is nevertheless desirable to reduce the production of such elements for health and / or environmental reasons. Description of the invention

[0010] An object of the invention is to propose a solution to reduce the amount of carbon dioxide produced in relation to an installation for the production of mineral fibers known for an equivalent quantity of mineral fibers produced.

[0011] This objective is achieved within the framework of the present invention by means of a process for manufacturing mineral fibers using an installation comprising: - an annular burner, the burner comprising a combustion chamber and a nozzle, the nozzle connecting the combustion chamber to the outside of the burner, - a fiber-forming plate with orifices, adapted to receive a molten thermoplastic material, in particular a mineral material, preferably glass, and adapted to form filaments of the thermoplastic material from the orifices by centrifuging the plate, the process comprising at least: - a first stage in the manufacturing of filaments, - a second stage of injecting a first fluid into the combustion chamber at a first flow rate, the first fluid comprising a fuel, the fuel comprising dihydrogen, a volume fraction of dihydrogen in the first fluid being greater than 0.05, - a third stage of injecting a second fluid into the combustion chamber at a second flow rate, the second fluid having an oxygen volume fraction greater than 0.10, - a fourth combustion stage of the fuel and oxygen introduced into the combustion chamber during the second and third stages, - a fifth filament stretching stage, the nozzle being arranged so that compounds contained in the combustion chamber following the combustion of the fourth stage are evacuated by the nozzle outside the burner and then stretch the filaments made in the first stage so as to form the mineral fibers.

[0012] The present invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:

[0013] - during the fourth stage, a pressure PB in the combustion chamber is between 1961 Pa (200 mm CE) and 7845 Pa (800 mm CE), in particular between 4413 Pa (450 mm CE) and 7355 Pa (750 mm CE) and preferably between 5394 Pa (550 mm CE) and 6374 Pa (650 mm),

[0014] - the plate has a diameter DA, the nozzle has a cross-section of diameter DT, and The average momentum of the compounds through the nozzle section during the fifth stage is between 2k.Dt.1961.(Da+Dt) and 2n.DT ,7354.(DA+DT), notably included between 2tï.Dt.4413.(Da+Dt) and 2tï.Dt.7355.(Da+Dt) and preferably included between 2k.Dt.5393.(Da+Dt) and 2n.DT.6374.(DA+DT),

[0015] - a richness q> of a set formed by a mixture of the first fluid and the second fluid in the combustion chamber is between 0.40 and 0.90, in particular between 0.50 and 0.80 and preferably between 0.60 and 0.70,

[0016] - the fuel comprises an organic compound and preferably methane,

[0017] - a lip defines a boundary between the nozzle and the outside of the burner, and, during the fourth stage, a temperature measured on the lip is between 1100 °C and 1600 °C, specifically between 1200 °C and 1550 °C and preferably between 1300 °C and 1550 °C,

[0018] - a composition of the first fluid and a composition of the second fluid end at a flame speed of 5 / during the fourth combustion stage, and the first fluid and the second fluid are mixed, preferably in the burner, before being introduced into the combustion chamber so as to form a mixture, the mixture being injected into the combustion chamber during the second stage and during the third stage, the average speed U of the mixture during the injection of the mixture into the combustion chamber being greater than or equal to the flame speed Sf,

[0019] - the first fluid and the second fluid are mixed, preferably in the burner, before being introduced into the combustion chamber so as to form a mixture, the mixture having a pressure greater than 102,000 Pa, and preferably greater than 103,000 Pa,

[0020] - the first fluid and the second fluid are mixed in the burner before being introduced into the combustion chamber,

[0021] - the burner includes an injector, the injector including a first inlet fluid, a second fluid inlet, a mixing duct fluidically connected to the first fluid inlet and the second fluid inlet, and comprising an outlet fluidly connecting the mixing duct to the combustion chamber, the geometry of the injector being configured such that, upon injection of the first fluid and the second fluid into the injector, the first fluid and the second fluid flow along at least a portion of the mixing duct in the same principal flow direction and so as to exhibit a rotation of the second fluid relative to the first fluid around an axis oriented along the principal flow direction,

[0022] - the injector includes an angular deflection element adapted to generate a vortex flow of the first fluid and / or the second fluid in the mixing duct,

[0023] - the volume fraction of dihydrogen in the first fluid is between 0.15 and 0.20, and the first fluid and the second fluid are mixed before being injected into the burner,

[0024] - the burner is configured to supply the injector separately with first fluid and as a second fluid,

[0025] - the geometry of the nozzle, the geometry of the burner, the first flow rate, the second flow rate, a composition of the first fluid and a composition of the second fluid are determined so that the pressure PB in the combustion chamber is between 1961 Pa (200 mm CE) and 7845 Pa (800 mm CE), in particular between 4413 Pa (450 mm CE) and 7355 Pa (750 mm CE) and preferably between 5394 Pa (550 mm CE) and 6374 Pa (650 mm),

[0026] - the plate has a diameter DA, the nozzle has a cross-section of diameter DT and the geometry of the nozzle, the geometry of the burner, the first flow rate, the second flow rate, a composition of the first fluid and a composition of the second fluid are determined such that the average momentum of the compounds through the section of the nozzle during the fifth stage is between 2k.Dt.1961.(Da+D t) and 2n.DT.7354.(DA+DT), in particular between 2k.Dt.4413.(Da+Dt) and 2k.Dt.7355.(Da+Dt) and preferably between 2k.Dt.5393.(Da+Dt) and 2^.D,.6374 ■ (Da+ Dt),

[0027] - the first flow rate, the second flow rate, a composition of the first fluid and a com The position of the second fluid is chosen so that a richness q> of a mixture of the first and second fluids in the combustion chamber is between 0.40 and 0.90, in particular between 0.50 and 0.80 and preferably between 0.60 and 0.70,

[0028] - the first fluid has a volume fraction of dihydrogen greater than 0.2, in particular greater than 0.5.

[0029] Another aspect of the invention is an installation for the manufacture of mineral fibers comprising: - an annular burner, the burner comprising a combustion chamber and a nozzle, the nozzle connecting the combustion chamber to the outside of the burner, - a fiber-forming plate having orifices, adapted to receive a molten thermoplastic material, in particular a mineral material, and adapted to form filaments of the thermoplastic material from the orifices by centrifugation of the plate, the burner comprising: -a first inlet, configured to receive a first fluid, the first fluid comprising a fuel, the fuel comprising dihydrogen, a volume fraction of dihydrogen in the first fluid being greater than 0.05, the first inlet being fluidly connected to the combustion chamber, - a second inlet, configured to receive a second fluid, the second fluid having an oxygen volume fraction greater than 0.10, the second inlet being fluidly connected to the combustion chamber.

[0030] Advantageously, the installation comprises an injector, the injector comprising a first fluid inlet, a second fluid inlet, a mixing conduit fluidically connected to the first fluid inlet and the second fluid inlet, and comprising an outlet fluidly connecting the mixing conduit to the combustion chamber, the first burner inlet being fluidly connected to the first fluid inlet of the injector, the second burner inlet being fluidly connected to the second fluid inlet of the injector, the geometry of the injector being configured so that, when the first fluid and the second fluid are injected into the injector, the first fluid and the second fluid flow along at least part of the mixing conduit in the same principal flow direction and so as to exhibit a rotation of the second fluid relative to the first fluid around an axis oriented along the principal flow direction. Description of the figures

[0031] Other features, objectives and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0032] [Fig-1] - [Fig.1] schematically illustrates a fiber production installation known minerals,

[0033] [Fig.2] - [Fig.2] schematically illustrates a mineral fiber production installation according to an embodiment of the invention,

[0034] [Fig.3] - [Fig.3] schematically illustrates a process according to one embodiment of the invention,

[0035] [Fig.4] - [Fig.4] schematically illustrates the drawing of filaments according to one embodiment of the invention,

[0036] [Fig.5] - [Fig.5] illustrates a variation of a mass flux of momentum with a total flow rate of fuel introduced into a combustion chamber,

[0037] [Fig.6] - [Fig.6] illustrates a variation in mass momentum flux with a richness of reactants injected into a combustion chamber,

[0038] [Fig.7] - [Fig.7] illustrates a variation in the temperature of a burner lip with a richness of reactants injected into a combustion chamber,

[0039] [Fig.8] - [Fig.8] schematically illustrates the stabilization of a flame in a combustion chamber,

[0040] [Fig.9] - [Fig.9] schematically illustrates part of an injector according to one embodiment of the invention,

[0041] [Fig. 10] - [Fig. 10] schematically illustrates part of a burner comprising an injector according to an embodiment of the invention,

[0042] [Fig. 11] - [Fig. 11] schematically illustrates gas flows in an injector and in a combustion chamber according to an embodiment of the invention,

[0043] [Fig. 12] - [Fig. 12] schematically illustrates a ring forming an angular deflection element according to one embodiment of the invention,

[0044] [Fig. 13] - [Fig. 13] schematically illustrates a ring forming an angular deflection element according to one embodiment of the invention,

[0045] [Fig. 14] - the [Fig. 14] schematically illustrates a ring forming an angular deflection element according to an embodiment of the invention.

[0046] Throughout the figures, similar elements bear identical references. Definition

[0047] The term “richness q>” of a combustion reaction means a ratio between, on the one hand, the ratio between the mass of fuel and between the mass of air used in a combustion reaction, and on the other hand, the ratio between the mass of fuel and between the mass of air used in a reaction of the same combustion under stoichiometric conditions. Detailed description of the invention

[0048] With reference to [Fig. 2] and [Fig. 3], one aspect of the invention is a method 300 for manufacturing mineral fibers 1. The mineral fibers 1 are manufactured by an installation 2. The installation 2 comprises an annular burner 3. The annular burner 3 comprises a combustion chamber 4 and a nozzle 5. The nozzle 5 connects the combustion chamber 4 to the outside of the burner 3.

[0049] The installation 2 includes a fiber-forming plate 6 having orifices 7. The plate 6 is adapted to receive a molten thermoplastic material, in particular a mineral material and preferably glass. The plate 6 is also adapted to form filaments 8 of the molten thermoplastic material from the orifices 7 by centrifuging the plate 6.

[0050] The process 300 includes a first step 301 for manufacturing the filaments. The first step 301 includes, in a known manner, a centrifugal projection of the molten thermoplastic material onto the first annular wall 20. The material then flows into the plurality of orifices 7 of the first annular wall 20 so as to form filaments 8 of the material.

[0051] The process 300 comprises a second step 302 of injecting a first fluid 9 in combustion chamber 4 at a first flow rate. The first fluid 9 comprises a fuel. The fuel comprises dihydrogen. A volume fraction of dihydrogen in the first fluid 9 is greater than 0.15, in particular greater than 0.2 and preferably greater than 0.5. The fuel may also comprise at least one organic compound. The organic compound(s) may be selected from methane, biogas, propane, and liquefied petroleum gas. The fuel may comprise a mixture of the organic compound(s) and dihydrogen, and preferably a mixture of methane and dihydrogen.

[0052] The process 300 includes a third step 303 of injecting a second fluid 10 into the combustion chamber 4 at a second flow rate. The second fluid 10 has an oxygen volume fraction greater than 0.1. Preferably, the second fluid 10 is air. The second step 302 and the third step 303 are preferably carried out simultaneously.

[0053] The process 300 includes a fourth step 304 of combustion of the fuel injected into the combustion chamber 4 during the second step and of the oxygen injected into the combustion chamber 4 during the third step.

[0054] The process 300 includes a fifth step of drawing the filaments 8. The nozzle 5 is arranged so that compounds contained in the combustion chamber 4 following the combustion of the fourth step are evacuated by the nozzle outside the burner 3 and then draw the filaments 8 produced in the first step so as to form the mineral fibers 1. Thus, by replacing part of the hydrocarbon used for combustion with dihydrogen, it is possible to reduce the amount of carbon dioxide produced while drawing a constant amount of filaments so as to produce mineral fibers by centrifugation.

[0055] Theoretical basis of the invention

[0056] The fuel may comprise methane and dihydrogen. A stoichiometric combustion reaction of a mixture comprising methane and dihydrogen with air can be modeled by the following equation:

[0057] [Math.l] (CH4 + aH2) + (^)(C»2 + 3.76Æ2) CO2 + (2 + d)H2O + 3J6(^ )iV2 where a is equal to the number of moles of dihydrogen.

[0058] A combustion reaction in excess air of a mixture comprising methane and dihydrogen with air can be modeled by the following equation:

[0059] [Math.2] ( CH4 + aH2 ) + ( ) À ( O2 + 3.76 AL ) CO2 + ( 2 + a ) H^O + 3.762 ( ) N2 + ( ) ( À -1 ) O2 where X is the air ratio which is defined by the following equation:

[0060] [Math.3] ; — 2 — AFR $ AFRSC where q> is the richness, AFR is the dosage, also called in English air fuel ratio, and AFRst is the ideal dosage, also called stoichiometric dosage or in English stoichiometric air fuel ratio.

[0061] The AFR assay can be defined by the following equation:

[0062] [Math.4] _ Flxfr _ _____P Air La» _ _________KO ^Air_______ rhcH4+rhH2 PcHfQcHfPu*QH, (McH*Qcf]+MH,*QH)

[0063] where mÆr is the mass flow rate of air introduced into the combustion chamber, rhc / / 4 is the mass flow rate of methane introduced into the combustion chamber, rïl / / 7 is the mass flow rate of dihydrogen introduced into the combustion chamber, P Air is the density of the air when it is introduced into the combustion chamber, Q,.is the air flow rate upon its introduction into the combustion chamber, PciiA is the density of methane upon its introduction into the combustion chamber, QCH is the methane flow rate upon its introduction into the combustion chamber, Ph2 is the density of dihydrogen upon its introduction into the combustion chamber, is the dihydrogen flow rate upon its introduction into the combustion chamber, Pinitial is the air pressure at the inlet of combustion chamber 4, R is the universal ideal gas constant, TinitM is the temperature at the inlet of combustion chamber 4, MAir is the molar mass of air, Mcha is the molar mass of methane and ^h2 is the molar mass of dihydrogen. .

[0064] The ideal AFRsl dosage can be defined by the following equation:

[0065] [Math.5] (noj ( 32+3.76*28) st sf^n, (16+2à)

[0066] where "O2 is the quantity of dioxygen introduced into the combustion chamber 4, is the quantity of nitrogen introduced into the combustion chamber 4, Pcif is the quantity of methane introduced into the combustion chamber 4 and nH2 is the quantity of dihydrogen introduced into the combustion chamber 4.

[0067] Thus, the general combustion equation including methane and dihydrogen as fuels can be defined by the following formula: [Math.6] (ncffiCH4+aH2) + ),1(^+3.76^,) -*nCHtCO-,+ (2iicni + a)HO + 3.76i.(^^ )n2 +

[0068] Thus, to know the composition of the combustion products, it is necessary to know three parameters: the quantity of methane introduced into the chamber of combustion 4, the quantity of dihydrogen introduced into the combustion chamber 4 and X. In addition, it is possible to calculate an adiabatic flame temperature and a lip temperature 11 from the previous equations by calculating the molar enthalpies of the products and reactants of the previous equation.

[0069] Drawing of filaments 8

[0070] The fifth step 305 of drawing the filaments 8 allows the mineral fibers 1 to be formed by applying an aerodynamic force driven by the compounds expelled from the combustion chamber 4 on the filaments 8 during the combustion of the fourth step 304. The acceleration of the drawing driven by this aerodynamic force controls the diameter of the mineral fibers 1.

[0071] With reference to [Fig. 4], the stretching of the filaments 8 is locally controlled by a surface density jp of momentum flux at the lips 11 of the burner 3. The surface density jp is defined by the following equation:

[0072] [Math.7]

[0073] where Mb is a mass flux of momentum and where S is a cross-section through which the compounds contained in the combustion chamber 4 are expelled by the nozzle from the burner 3 following the combustion of the fourth stage. The nozzle 5 connects the combustion chamber 4 to the outside of the burner 3. One end of the nozzle 5 forms two lips 11 defining a cross-section through which the compounds contained in the combustion chamber 4 are expelled from the burner 3 following the combustion of the fourth stage. The cross-section S is defined by the lips 11 of the burner 3.

[0074] With reference to [Fig. 5], the mass flux MB of momentum decreases for a proportion of dihydrogen that increases during combustion determined by a constant air-fuel ratio q. Curve (a) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel consisting solely of methane, for an air-fuel ratio q equal to 0.69. Curve (b) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel consisting of 90% methane and 10% dihydrogen, for an air-fuel ratio q equal to 0.69. Curve (c) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel consisting of 80% methane and 20% dihydrogen, for an air-fuel ratio q equal to 0.69. Curve (d) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel consisting of 70% methane and 30% dihydrogen, for an air-fuel ratio q equal to 0.69.Curve (e) illustrates the mass flow MB as a function of the total fuel flow rate, the fuel consisting solely of dihydrogen, for a richness q > equal to 0.69.

[0075] The mass flux MB of momentum is defined by the following equation:

[0076] [Math. 8] MB^Q^UB^PBS

[0077] where Qb is the mass flow rate of compounds evacuated outside burner 3, UB is the velocity of compounds evacuated outside burner 3 and PB is the pressure in combustion chamber 4.

[0078] Thus, the pressure PB in the combustion chamber 4 allows control of the stretching of the filaments 8 so that the formed mineral fibers 1 exhibit thermal and / or acoustic insulation characteristics. Preferably, during the fourth step 304, the pressure PB in the combustion chamber 4 is between 1961 Pa (200 mm CE) and 7845 Pa (800 mm CE), in particular between 4413 Pa (450 mm CE) and 7355 Pa (750 mm CE), and preferably between 5394 Pa (550 mm CE) and 6374 Pa (650 mm CE). Therefore, it is possible to manufacture mineral fibers 1 with a flow rate between 3 L / min and 24 L / min, in particular between 6 L / min and 20 L / min, using at least some of dihydrogen as fuel. The rotation speed of the plate can be greater than 2000 rpm. The fiber pull by the plate can be less than 1 kg per day per orifice 7 of the plate 6, and in particular less than 0.6 kg per day per orifice 7 of the plate 6.

[0079] The combustion defined by the fourth step 304 is preferably continuous. Thus, during the fourth step 304, the pressure PB in the combustion chamber 4 can be maintained between 1961 Pa (200 mm CE) and 7845 Pa (800 mm CE). By "maintained" is meant that the pressure is maintained for a period greater than 10 minutes, in particular greater than one hour, preferably greater than three hours.

[0080] The pressure PB in the combustion chamber 4 can be determined by the geometry of the combustion chamber 4, the geometry of the nozzle 5, the first flow rate, the second flow rate, a composition of the first fluid 9 and a composition of the second fluid 10. For example, a combustion chamber 4 and a nozzle 5 described in document WO 03 / 069226 can be used. The combustion reaction can be maintained in the combustion chamber 4 by introducing a mass flow rate of methane equal to 9.96 kg / h, a mass flow rate of dihydrogen equal to 0.75 kg / h, the volume fraction of dihydrogen in the first fuel thus being 0.07, and a mass flow rate of the second fluid consisting of air equal to 285 kg / h. The combustion reaction described above allows a mass flux MB of 18.9 Kg.m / s2 to be applied to the plate while controlling a pressure PB in the combustion chamber 4 of 6002 Pa (612 mm CE).

[0081] The fourth step 304 may be preceded by a combustion ignition step. During the combustion ignition step, a pressure PB in the combustion chamber may be between 0 Pa (0 mm CE) and 1961 Pa (200 mm CE).

[0082] The plate has a diameter DA and the nozzle has a cross-section of diameter DT. Due to the PB pressures in the combustion chamber 4 previously defined, an average momentum of the compounds through the nozzle section during the fifth stage can be between 2k.Dt.1961.(Da+Dt) and 2n.DT ,7354.(Da+Dt), in particular between 2k.Dt.4413.(Da+Dt) and 2k.Dt.7355.(Da+Dt) and preferably between 2k.Dt.5393.(Da+Dt) and 2k.Dt.6374.(Da+Dt). For a diameter DT equal to 7.7 mm and for a diameter DA of the plate equal to 400 mm, an average momentum of the compounds through the section of the nozzle during the fifth stage can be between 38.7 kg.m.s2 and 154 kg.m.s2, in particular between 87.0 kg.m.s2 and 145 kg.m.s2 and preferably between 106 kg.m.s2 and 126 kg.m.s2.For a diameter DT equal to 7.7 mm and for a diameter DA of the plate equal to 600 mm, an average momentum of the compounds through the nozzle section during the fifth stage can be between 57.7 kg.m.s2 and 231 kg.m.s2, in particular between 130 kg.m.s2 and 216 kg.m.s2 and preferably between 159 kg.m.s2 and 187 kg.m.s2.

[0083] Combustion richness

[0084] With reference to [Fig. 6], the air-fuel ratio q of a mixture of the first fluid 9 and the second fluid 10 in the combustion chamber 4 is between 0.40 and 0.90, in particular between 0.50 and 0.80, and preferably between 0.60 and 0.70. Thus, it is possible to compensate for a decrease in the mass flux density MB caused by the use of dihydrogen in combustion by injecting a higher proportion of the second fluid 10 into the chamber 4. This makes it possible to implement combustion using dihydrogen as fuel while producing a mass flux density MB sufficient to stretch the filaments 8 formed by centrifugation. For air-fuel ratio values ​​below 0.40, flame stability in the combustion chamber 4 is not guaranteed.For richness values ​​greater than 0.90, the mass flux density MB is too small to stretch the filaments 8 to form the mineral fibers 1, and fuel is present in the evacuated compounds, which is polluting. Figure 6 illustrates mass flux densities MB as a function of richness q for a molar ratio of dihydrogen to methane of 0.43. The richness q of the combustion reaction of the fourth stage 304 can be determined by the first flow rate, by the second flow rate, by a composition of the first fluid 9 and by a composition of the second fluid 10.

[0085] Temperature of a lip 11 of the burner 3

[0086] With reference to [Fig.7], at least one lip 11 defines a boundary between the nozzle 5 and the outside of burner 3. A lip temperature 11 can be calculated based on the reactants introduced into the combustion chamber, considering in particular the reaction equations presented previously and the molar enthalpies of the The curve (f) illustrates the temperature of lip 11 as a function of the gas richness q of the combustion reaction for a volume fraction of zero dihydrogen and for a volume fraction of methane equal to 1. The curve (g) illustrates the temperature of lip 11 as a function of the gas richness q of the combustion reaction for a volume fraction of dihydrogen equal to 0.11 and for a volume fraction of methane equal to 0.89. The curve (h) illustrates the temperature of lip 11 as a function of the gas richness q of the combustion reaction for a volume fraction of dihydrogen equal to 0.25 and for a volume fraction of methane equal to 0.75. The curve (i) illustrates the temperature of lip 11 as a function of the gas richness q of the combustion reaction for a volume fraction of dihydrogen equal to 0.43 and for a volume fraction of methane equal to 0.57.Curve (j) illustrates the temperature of lip 11 as a function of the richness q> of the combustion reaction for a volume fraction of dihydrogen equal to 1 and for a volume fraction of methane of zero.

[0087] During the fourth step 304, a temperature measured on the lip 11 can be between 1100 °C and 1600 °C, in particular between 1200 °C and 1550 °C and preferably between 1300 °C and 1550 °C. The volume fraction of dihydrogen in the fuel and / or the air-fuel ratio can be adjusted so that the temperature measured on the lip 11 is within the ranges defined above. Preferably, a richness q> of a set formed by a mixture of the first fluid 9 and the second fluid 10 in the combustion chamber 4 is between 0.40 and 0.90, in particular between 0.50 and 0.80 and preferably between 0.60 and 0.70, and a temperature measured on the lip 11 can be between 1100 °C and 1600 °C, in particular between 1200 °C and 1550 °C and preferably between 1300 °C and 1550 °C.The inventors have indeed discovered that it is possible to produce mineral fibers 1 by centrifugation by combining these different parameters and using dihydrogen as fuel. A temperature measured on the lip 11 can be maintained at a temperature between 1100 °C and 1600 °C during the fourth combustion stage 304.

[0088] Flame stability

[0089] With reference to [Fig. 8], a composition of the first fluid 9 and a composition of the second fluid 10 define a flame speed S / during the fourth combustion stage 304. "Flame speed" is understood to be the speed of the flame front extension during the combustion reaction. The flame speed depends on the rate of fuel and oxidizer consumption during the combustion reaction. The first fluid 9 and the second fluid 10 can be mixed, preferably in the burner 3, before being introduced into the combustion chamber 4 to form a mixture. The mixture can be injected into the combustion chamber. Combustion 4 occurs during the second stage 302 and the third stage 303. An average velocity U of the mixture upon injection into the combustion chamber 4 can be greater than or equal to the flame velocity Sf. This prevents flashback during the combustion reaction. Indeed, if the flame velocity Sf is higher than the average velocity U, the flame travels towards the source of the mixture, leading to risks of explosion or burner damage.

[0090] Initial pressure of the first fluid 9

[0091] The first fluid 9 and the second fluid 10 can be mixed, preferably in the burner 3, before being injected into the combustion chamber 4. The mixture injected into the combustion chamber 4 can have a pressure greater than 102,000 Pa and preferably greater than 103,000 Pa. Thus, by increasing the pressure of the mixture, it is possible to increase the temperature of the mixture before combustion. This makes it possible to increase the adiabatic temperature of the flame during combustion, and thus, for a predetermined adiabatic flame temperature, to reduce the production of carbon dioxide.

[0092] Mixture of the first fluid 9 and the second fluid 10

[0093] The first fluid 9 and the second fluid 10 can be mixed in the burner 3 before being introduced into the combustion chamber 4. Thus, it is possible that the compounds of the first fluid 9 and the second fluid 10 are distributed homogeneously in the combustion chamber 4 while avoiding a risk of combustion outside the burner 3 potentially caused by a mixing of the first fluid 9 and the second fluid 10 upstream of the burner 3.

[0094] With reference to [Fig. 9], the burner 3 may include an injector 12. The injector 12 includes a first fluid inlet 9, a second fluid inlet 10, a mixing line 13 fluidly connected to the first fluid inlet 9 and to the second fluid inlet 10. A lateral line 24 fluidly connects the first fluid inlet 9 to the mixing line 13. The injector 12 includes an outlet 28 separating the mixing line 13 from the combustion chamber 4.

[0095] The geometry of the injector 12 is configured so that, when the first fluid 9 and the second fluid 10 are injected into the injector 12, the first fluid 9 and the second fluid 10 flow along at least a portion of the mixing line 13 in the same principal flow direction 14, and such that the second fluid 9 rotates relative to the first fluid 10 around an axis oriented along the principal flow direction 14. Thus, the density of the first fluid 9 and the density of the second fluid 10 are more homogeneous in the combustion chamber 4 than in the absence of the injector 12 as previously defined. This increases flame stability during combustion. Indeed, it can be advantageous to implement the process in a so-called "lean" regime, i.e., for a lower fuel-air ratio. at 0.9. If the first fluid 9 and the second fluid 10 are not distributed homogeneously in the combustion chamber 4, the richness may be locally much lower than the richness predetermined by the flow rates of first fluid 9 and second fluid 10, which may lead to flame instability.

[0096] The injector 12 may include an angular deflection element 15 adapted to generate a vortex flow of the first fluid 9 and / or the second fluid 10 in the mixing conduit 13. Thus, the angular deflection element 15 makes it possible to implement a flow in which the first fluid 9 and the second fluid 10 flow along at least a portion of the mixing conduit 13 in the same principal flow direction 14 and such as to exhibit a rotation of the second fluid 9 relative to the first fluid 10 around an axis oriented along the principal flow direction 14. The angular deflection element 15 may be adapted to generate a vortex flow of the first fluid 9 or the second fluid 10 in the mixing conduit 13.

[0097] With reference to [Fig. 12], [Fig. 13] and [Fig. 14], the angular deflection element 15 can have a vortex number S which satisfies the equation S = 2 / 3 tan(rp), rp being the angular deflection angle of the flow of first fluid 9 and / or second fluid 10 after passing through the injector 15. The vortex number S is between 0.10 and 2.00, preferably between 0.25 and 1.70, more preferably between 0.35 and 1.40, more preferably between 0.45 and 1.10, more preferably between 0.50 and 0.90, more preferably between 0.65 and 0.70.

[0098] The intensity of the rotary motion of the flow is characterized by the value of the swirl number S at the injector outlet 12. The swirl number S defines the ratio between the tangential and axial momentum fluxes. It can be defined by the following equation:

[0099] [Math.9] _ f(. UWr^dr 7fJ0 U2rdr where U and W are respectively the axial and tangential components of the average flow velocity, and Re is the radius of the mixing pipe 13. This vortex number S is approximated by the formula S = 2 / 3 tan rp-

[0100] Increasing the number of vortices S reduces the flame height and increases the flame opening. A wide flame opening limits the number of injectors arranged around the perimeter of the combustion chamber 4, while still allowing for homogeneous heating of the latter.

[0101] With reference to [Fig. 10] and [Fig. 11], the angular deflection element 15 can be formed, at least in part, by a ring arranged coaxially to the Main flow direction 14. The ring may be removable. The ring may include a conduit adapted to allow the introduction of the swirling flow of the first fluid 9 and / or the second fluid 10 into the mixing conduit 13 of the injector 12 with an angular deflection angle rp, the value of which is preferably between 10° and 80°, in particular between 20° and 70°, more preferably between 30° and 60°, and again preferably between 40° and 50°. Thus, it is possible to maximize the mixing between the first fluid 9 and the second fluid 10 before their introduction into the combustion chamber 4. It is therefore possible to reduce the quantity of fuel to be injected, for the same quantity of oxidant involved in combustion. The conduit adapted to allow the introduction of the swirling flow may form part of the lateral conduit 24.

[0102] The angular deflection element can be a set of deflectors arranged in the mixing conduit 13 so as to rotate the flow of the first fluid 9 and the second fluid 10 around an axis along the main direction 14.

[0103] With reference to [Fig. 10], the burner 3 is configured to supply the injector 12 separately with a first fluid 9 and a second fluid 10. The burner 3 may include a first inlet 26 for the first fluid 9. The injector 12 may include an axial conduit 25 fluidically connecting the first inlet 26 to the mixing conduit 13. The burner 3 may include a second inlet 27 for the second fluid 10. The second inlet 27 may be connected to the lateral conduit 24. The mixing of the first fluid 9 and the second fluid 10 takes place in the mixing conduit 13 before being injected into the combustion chamber 4 of the burner 3. Thus, by separating the first inlet 26 and the second inlet 27, it is possible to prevent a flashback upstream of the burner 3.

[0104] With reference to [Fig. 11], a wall of the lateral conduit 24 may have a frustoconical shape, the frustoconical shape having a principal axis along the principal direction 14. The diameter of the frustoconical shape may be decreasing along the principal direction 14. Thus, it is possible to avoid separation of the boundary layer of the vortex flow, in order to reduce the risks of the appearance of unwanted turbulence.

[0105] The second fluid 10 can be preheated, preferably by at least 5°C, before being injected into the burner 3. The preheating of the second fluid 10 can be carried out by recovering heat from the gases from the combustion of the fourth stage 304 and / or heat from the glass melting furnace.

[0106] The vortex flow generated in the mixing line 13 causes recirculation of the fluids in the combustion chamber 4. This recirculation allows the flame generated during combustion to adhere near the injector outlet in the combustion chamber 4. Flame adhesion is promoted by the presence of toroidal recirculation zones which bring back part of the burnt gases towards the outlet of the injector, which leads to a preheating of the gases coming from injector 12. The flame being more stable, it is thus possible to reduce the amount of fuel used for combustion without risking blowing out the flame.

[0107] The axial conduit 25 may have an outlet in the mixing conduit 13. The distance between the outlet of the axial conduit 25 and the outlet of the injector 13 may be strictly between 0 and 45 mm. Thus, since the distance is less than 45 mm, it is possible to increase the mixing efficiency. Furthermore, since the distance is strictly greater than zero, it is possible to limit injector wear caused by high combustion temperatures. The distance is in particular greater than 5 mm, preferably greater than 10 mm, preferably greater than 15 mm, and preferably greater than 20 mm.

[0108] The outlet of the injector 12 may have a straight cross-section. By "straight cross-section," it is understood that the outlet of the injector 12 is formed by the wall of the mixing line 13 at the same point along the main direction 14. Indeed, the inventors have observed that cutting an injector outlet at a bevel, as practiced in the prior art, impedes the swirling circulation of the oxidizer / fuel mixture and therefore reduces the associated beneficial technical effects. Conversely, cutting the injector outlet with a straight cross-section increases flame stability during combustion.

[0109] The combustion chamber 4 is formed by at least one wall. The wall includes a distal portion. The outlet 28 can be arranged at the center of the distal portion with respect to the principal axis X. Thus, the outlet is arranged equidistant from the upper and lower walls of the combustion chamber 4, which allows, through gas recirculation, for a more homogeneous and stable flame.

[0110] A section of the outlet 28 may have a diameter adapted to the flame's stabilization distance. The smaller the diameter, the greater the flow velocity of the mixture at the outlet 28, which increases the flame's stabilization distance. The flame is then said to be "lifted." Beyond a certain ejection velocity, the flame is said to be "blown out." Conversely, the larger the diameter, the lower the flow velocity at the outlet 28. Below a predetermined flow velocity of the mixture at the outlet 28, the flame risks stabilizing inside the injector 12, which is undesirable.

[0111] The burner 3 may include several injectors 12. The burner 3 may include a distribution ring for first fluid 9 and / or second fluid 10 in the injectors 12. The ring may include inlets evenly distributed around its periphery. The number of inlets may be equal to the number of injectors. Thus, the fluid flow can be homogeneous in the injectors 12. The increase in The number of crown inlets allows for increased homogeneity of fluid distribution in the injectors.

Claims

Demands

1. A method for manufacturing mineral fibers (1) by means of an installation (2) comprising: - an annular burner (3), the burner (3) comprising a combustion chamber (4) and a nozzle (5), the nozzle (5) connecting the combustion chamber (4) to the outside of the burner (3), - a fiber-forming plate (6) having orifices (7), adapted to receive a molten thermoplastic material, in particular a mineral material, and adapted to form filaments (8) of the thermoplastic material from the orifices (7) by centrifugation of the plate (6), the process comprising at least: - a first stage of filament manufacturing (8), - a second stage of injecting a first fluid (9) into the combustion chamber (4) at a first flow rate, the first fluid (9) comprising a fuel, - a third stage of injecting a second fluid (10) into the combustion chamber (4) at a second flow rate, the second fluid (10) having an oxygen volume fraction greater than 0.10, - a fourth stage of combustion of the fuel and oxygen introduced into the combustion chamber (4) during the second and third stages, - a fifth filament drawing stage (8), the nozzle (5) being arranged so that compounds contained in the combustion chamber (4) following the combustion of the fourth stage are evacuated by the nozzle outside the burner (3) and then draw the filaments (8) produced during the first stage so as to form the mineral fibers (1), the process being characterized in that, during the second stage the fuel comprises dihydrogen, a volume fraction of di-hydrogen in the first fluid (9) being greater than 0.05, and in that during the fourth stage, a pressure PB in the combustion chamber is between 1961 Pa (200 mm CE) and 7845 Pa (800 mm CE).

2. A method according to claim 1, wherein, during the fourth step, a pressure PB in the combustion chamber is between 4413 Pa (450 mm CE) and 7355 Pa (750 mm CE) and preferably between 5394 Pa (550 mm CE) and 6374 Pa (650 mm).

3. Method according to claim 1 or 2, wherein a richness q> of an assembly formed by a mixture of the first fluid (9) and the second fluid (10) in the combustion chamber (4) is between 0.40 and 0.

90.

4. A method according to any one of claims 1 to 3, wherein the fuel comprises an organic compound, in particular methane.

5. A method according to any one of the preceding claims, wherein a lip (11) defines a boundary between the nozzle (5) and the outside of the burner (3), and wherein, during the fourth step, a temperature measured on the lip (11) is between 1100 °C and 1600 °C.

6. A method according to any one of the preceding claims, wherein a composition of the first fluid (9) and a composition of the second fluid (10) define a flame speed S / during the fourth combustion stage, and wherein the first fluid (9) and the second fluid (10) are mixed, preferably in the burner (3), before being introduced into the combustion chamber (4) so ​​as to form a mixture, the mixture being injected into the combustion chamber (4) during the second stage and during the third stage, the average speed U of the mixture during the injection of the mixture into the combustion chamber (4) being greater than or equal to the flame speed Sf.

7. A method according to any one of the preceding claims, wherein the first fluid (9) and the second fluid (10) are mixed, preferably in the burner (3), before being introduced into the combustion chamber (4) so ​​as to form a mixture (4), the mixture having a pressure greater than 102000 Pa, and preferably greater than 103000 Pa.

8. A method according to any one of the preceding claims, wherein the first fluid (9) and the second fluid (10) are mixed in the burner (3) before being introduced into the combustion chamber (4).

9. The method of claim 8, wherein the burner (3) comprises an injector (12), the injector (12) comprising a first fluid inlet (9), a second fluid inlet (10), a mixing conduit (13) fluidly connected to the first fluid inlet (9) and the second fluid inlet (10), and comprising an outlet fluidly connecting the mixing conduit (13) to the combustion chamber (4), the geometry of the injector (12) being configured such that, during a injection of the first fluid (9) and the second fluid (10) into the injector (12), the first fluid (9) and the second fluid (10) flow along at least a part of the mixing conduit (13) in the same main flow direction (14) and so as to exhibit a rotation of the second fluid (9) relative to the first fluid (10) around an axis oriented along the main flow direction (14).

10. Method according to the preceding claim, wherein the injector (12) comprises an angular deflection element (15) adapted to generate a vortex flow of the first fluid (9) and / or the second fluid (10) in the mixing conduit (13).

11. A method according to any one of claims 1 to 7, wherein the volume fraction of dihydrogen in the first fluid (9) is between 0.15 and 0.2, and wherein the first fluid (9) and the second fluid (10) are mixed before being injected into the burner (3).

12. Method according to claim 9 or 10, wherein the burner (3) is configured to supply the injector (12) separately with first fluid (9) and second fluid (10).

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