Method for producing mineral fibers by means of low-carbon-emission centrifugal spinning

Abstract

The present invention relates to a method for producing mineral fibres 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 spinner suitable for forming filaments by means of centrifugal spinning, 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, the volume fraction of dihydrogen in the first fluid being greater than 0.05. The pressure in the combustion chamber is between 1961 Pa and 7845 Pa.

Description

[0001] Description Title of the invention: Method for manufacturing mineral fibers by centrifugation with low carbon dioxide emissions Field of the invention [1] The present invention relates to a method for manufacturing mineral fibers by internal centrifugation and an installation suitable for implementing this method. The method can be applied in particular to the industrial manufacture of glass wool. State of the art [2] It is known to manufacture mineral wool by an internal centrifugation method. With reference to Figure 1, document FR305767 describes a known installation 2 for manufacturing mineral fibers 1 by internal centrifugation comprising a fiberizing plate 6, a basket 16 and a shaft 17 arranged along a main 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 in which a molten thermoplastic material can flow.The thermoplastic material is preferably glass. The installation 2 is configured to be arranged so that the main axis X is vertical in an earth reference frame and the thermoplastic material can be poured into the pipe 18 to fall into the basket 16. The pipe 18 is fluidically connected to a supply of molten thermoplastic material at one of its ends. The plate 6 and the basket 16 are fixedly mounted at the other end of the shaft by means of a tulip 19. [3] 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 R. aof the plate 6. The radius Ra is defined by the distance between the main axis X and a point A of the first wall 20 furthest from the main axis X. [4] 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 by the distance between the main axis X and a point B of the second wall 22 furthest from the main axis X. The basket is mounted inside the fiberizing plate. [5] During the manufacture of mineral fibers 1 by the installation 2, the shaft 17,the fiberizing plate 6 and the basket 16 are integrally driven 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 supply and flows in the conduit 18 to the basket 16. The material is projected onto the second annular wall 22 by centrifugation driven by the assembly of the shaft 17, the fiberizing 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. [6] When projecting the material onto the first annular wall 20,a reserve of material is formed in the fiberizing plate 6. The reserve makes it possible to continuously supply the plurality of orifices 7 of the first wall 20 to form the filaments 8. [7] The installation 2 comprises an annular burner 3. The annular burner 3 is configured to generate a gaseous drawing flow making it possible to draw the filaments 8 produced at the outlet of the orifices 8 of the first wall 20. The burner 3 has an axis of symmetry coincident with the main axis X of the shaft 17. The burner 3 has a gaseous outlet arranged above the first annular wall 20. The drawing gas flow leaving the burner 3 has a direction tangential to the first wall 20. The drawing gas flow makes it possible to heat both the first wall 20 and the filaments 8 which are formed at the outlet of the orifices 8 of the first wall 20. Under the action of the drawing gas flow, the filaments 8 stretch,then break to form mineral fibers 1. The mineral fibers 1 are then collected under the plate 6. [8] With reference to WO 03 / 069226, the drawing gas flow is produced by combustion in the annular burner 3. The annular burner 3 may comprise a combustion chamber 4 and a nozzle 5. The nozzle 5 connects the combustion chamber to the exterior of the burner 3. The combustion chamber 4 is supplied with oxidant and fuel. The combustion reaction is initiated in the combustion chamber. Methane is typically used as the fuel. Air is typically used as the oxidant. The combustion reaction described above makes it possible both to maintain a drawing gas flow having a sufficient drawing temperature at the lips 11 of the nozzle 5, for example between 1100°C and 1600°C and at the same time to maintain a sufficient gas flow rate to draw the filaments 8,for example between 5000 m³ / hour and 8000 m³ / hour. [9] However, the combustion reaction described above produces carbon dioxide in very large quantities and can produce nitrogen oxide, 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. Disclosure of the invention

[0010] An aim of the invention is to propose a solution for reducing the quantity of carbon dioxide produced with respect to an installation for the production of mineral fibers known for an equivalent quantity of mineral fibers produced.

[0011] This aim is achieved within the scope of the present invention by means of 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 fiberizing plate having 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 method comprising at least: - a first step of manufacturing the filaments, - a second 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, - a third step of injecting a second fluid into the combustion chamber at a second flow rate, the second fluid having a volume fraction of oxygen greater than 0.10,- a fourth stage of combustion of the fuel and oxygen introduced into the combustion chamber during the second stage and the third stage, - a fifth stage of drawing the filaments, 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 draw the filaments produced during the first stage so as to form the mineral fibers.

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

[0013] - during the fourth step, 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 an average quantity of movement of the compounds through the cross-section of the nozzle during the fifth stage is between 2π.DT.1961.(DA+DT) and 2π.DT.7354.(DA+DT), in particular between 2π.DT.4413.(DA+DT) and 2π.DT.7355.(DA+DT) and preferably between 2π.DT.5393.(DA+DT) and 2π.DT.6374.(DA+DT),

[0015] – a richness ^ of an assembly 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 step, a temperature measured on the lip is between 1100°C and 1600°C, in particular 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 define a flame speed S, fduring the fourth combustion step, 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 step and during the third step, 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 102000 Pa, and preferably greater than 103000 Pa,

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

[0021] - the burner comprises an injector, the injector comprising a first fluid inlet,a second fluid inlet, a mixing duct fluidly connected to the first fluid inlet and to the second fluid inlet, and comprising an outlet fluidly connecting the mixing duct to the combustion chamber, the geometry of the injector being configured so that, during an 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 main flow direction and so as to present a rotation of the second fluid relative to the first fluid around an axis oriented in the main flow direction,

[0022] - the injector comprises an angular deflection element adapted to generate a swirling 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 the first fluid and the 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 so that the average momentum of the compounds through the nozzle section during the fifth step is between 2π.DT.1961.(DA+DT) and 2π.DT.7354.(DA+DT), in particular between 2π.DT.4413.(DA+DT) and 2π.DT.7355.(DA+DT) and preferably between 2π.DT.5393.(DA+DT) and 2π.DT.6374.(DA+DT),

[0027] - the first flow rate, the second flow rate, a composition of the first fluid and a composition of the second fluid are chosen so that a richness ^ of an assembly 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,

[0028] - the first fluid has a dihydrogen volume fraction 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 fiberizing 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 centrifuging 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 fluidically connected to the combustion chamber, - a second inlet, configured to receive a second fluid,the second fluid having a volume fraction of oxygen greater than 0.10, the second inlet being fluidically connected to the combustion chamber.

[0030] Advantageously, the first inlet is configured to receive a first fluid at a first flow rate, the second inlet is configured to receive a second fluid at a second flow rate, and the installation comprises a control unit configured to control the first flow rate of first fluid and the second flow rate of second fluid 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).

[0031] Advantageously, the installation comprises an injector, the injector comprising a first fluid inlet, a second fluid inlet,a mixing duct fluidly connected to the first fluid inlet and to the second fluid inlet, and comprising an outlet fluidly connecting the mixing duct to the combustion chamber, the first inlet of the burner being fluidly connected to the first fluid inlet of the injector, the second inlet of the burner being fluidly connected to the second fluid inlet of the injector, the geometry of the injector being configured so that, during an 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 main flow direction and so as to present a rotation of the second fluid relative to the first fluid around an axis oriented in the main flow direction.

[0032] Description of the figures

[0033] Other characteristics, aims and advantages of the invention will emerge from the description which follows,which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0034] [Fig.1] - Figure 1 schematically illustrates a known mineral fiber production facility,

[0035] [Fig. 2] - Figure 2 schematically illustrates a mineral fiber production facility according to an embodiment of the invention,

[0036] [Fig.3] - Figure 3 schematically illustrates a method according to an embodiment of the invention,

[0037] [Fig.4] - Figure 4 schematically illustrates the drawing of filaments according to an embodiment of the invention,

[0038] [Fig. 5] - Figure 5 illustrates a variation of a mass flow of momentum with a total flow rate of fuel introduced into a combustion chamber,

[0039] [Fig. 6] - Figure 6 illustrates a variation of a mass flow of momentum with a richness of the reactants injected into a combustion chamber,

[0040] [Fig. 7] - Figure 7 illustrates a variation in the temperature of a lip of a burner with a richness of the reactants injected into a combustion chamber,

[0041] [Fig. 8] - Figure 8 schematically illustrates the stabilization of a flame in a combustion chamber,

[0042] [Fig. 9] - Figure 9 schematically illustrates a part of an injector according to an embodiment of the invention,

[0043] [Fig. 10] - Figure 10 schematically illustrates a part of a burner comprising an injector according to an embodiment of the invention,

[0044] [Fig.11] - Figure 11 schematically illustrates gas flows in an injector and in a combustion chamber according to an embodiment of the invention,

[0045] [Fig. 12] - Figure 12 schematically illustrates a ring forming an angular deflection element according to one embodiment of the invention,

[0046] [Fig. 13] - Figure 13 schematically illustrates a ring forming an angular deflection element according to an embodiment of the invention,

[0047] [Fig. 14] - Figure 14 schematically illustrates a ring forming an angular deflection element according to an embodiment of the invention.

[0048] Throughout the figures, similar elements bear identical references. Definition

[0049] The term "richness ^" of a combustion reaction is understood to mean 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

[0050] With reference to Figure 2 and Figure 3,one aspect of the invention is a method 300 for manufacturing mineral fibers 1. The mineral fibers 1 are manufactured by a plant 2. The plant 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.

[0051] The plant 2 comprises a fiberizing 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.

[0052] The method 300 comprises a first step 301 of manufacturing the filaments. The first step 301 comprises, in a known manner, a projection by centrifugation 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.

[0053] The method 300 comprises a second step 302 of injecting a first fluid 9 into the 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 chosen 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.

[0054] The method 300 comprises 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 implemented concomitantly.

[0055] The method 300 comprises 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.

[0056] The method 300 comprises 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 manufactured during 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 decrease the amount of carbon dioxide produced while drawing a constant amount of filaments so as to produce mineral fibers by centrifugation.

[0057] Theoretical bases of the invention

[0058] 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:

[0059] [Math 1] ( ) ^^^^ ^ ( ) ^^^

[0060] ^^, ^ + ^^ ^ + ^ ^ ^ + 3.76 ^ ^ → ^^ ^ + (2 + ^)^ ^ ^ + 3.76 ^ ^ ^ ^ ^ in which a is equal to the number of moles of dihydrogen.

[0061] An excess air combustion reaction of a mixture comprising methane and dihydrogen with air can be modeled by the following equation:

[0062] [Math 2]

[0063] ( ^^ ^ + ^^ ^ ) + ^^^^ ^ ^ ^ ( ^ ^ + 3.76 ^^^^ ^ ^ (^ − 1)^ ^ where λ is the air ratio which is defined by the following equation:

[0064] [Math 3] ^ ^^^

[0065] ^ = ^ = ^^^ ^^ where ^ is the richness, AFR is the dosage, also called in English air fuel ratio, and AFR st is the ideal dosage, also called stoichiometric dosage or in English stoichiometric air fuel ratio.

[0066] The AFR dosage can be defined by the following equation:

[0067] [Math 4]

[0069] where ṁ ^^^ is the mass flow rate of air introduced into the combustion chamber, ṁ ^^^ is the mass flow rate of methane introduced into the combustion chamber, ṁ ^^ is the mass flow rate of hydrogen introduced into the combustion chamber, ^ ^^^ is the density of the air when it is introduced into the combustion chamber, ^ ^^^ is the air flow rate when it is introduced into the combustion chamber, ^ ^^^is the density of methane when it is introduced into the combustion chamber, ^ ^^^ is the flow rate of methane when it is introduced into the combustion chamber, ^ ^^ is the density of dihydrogen when it is introduced into the combustion chamber, ^ ^^ is the flow rate of dihydrogen when it is introduced into the combustion chamber, ^ ^^^^^^^ is the air pressure at the inlet of the combustion chamber 4, R is the universal constant of ideal gases, ^ ^^^^^^^ is the temperature at the inlet of the combustion chamber 4, ^ ^^^ is the molar mass of air, ^ ^^^ is the molar mass of methane and ^ ^^ is the molar mass of dihydrogen.

[0070] The ideal dosage AFRst can be defined by the following equation:

[0071] [Math 5]

[0073] where ^ ^^ is the quantity of oxygen introduced into the combustion chamber 4, ^ ^^ is the amount of nitrogen introduced into the combustion chamber 4, ^^^^ is the amount of methane introduced into the combustion chamber 4 and ^ ^^ is the amount of dihydrogen introduced into the combustion chamber 4.

[0074] Thus, the general equation for combustion involving methane and dihydrogen as fuels can be defined by the following formula:

[0075] [Math 6] ^ ^^

[0076] ^^ ^^^ ^^ ^ + ^^ ^ ^ + ^ ^ ^^ ^ ^ ^ ^(^ ^ + 3.76 ^ ^ ) → ^ ^^^ ^^ ^ + ^2^ ^^^ + ^ ^ ^ ^^ ^^ ^ ^^ ^^ + 3.76^ ^ ^ ^ ^^ + ^^^ ^^ ^ ^^ ^ ^ ( ^ − 1 ) ^^

[0077] Thus, to know the composition of the combustion products, it is necessary to know three parameters: the quantity of methane introduced into the combustion chamber 4, the quantity of dihydrogen introduced into the combustion chamber 4 and λ. 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.

[0078] Drawing of the filaments 8

[0079] The fifth step 305 of drawing the filaments 8 makes it possible to form the mineral fibers 1 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.

[0080] With reference to Figure 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:

[0081] [Math 7]

[0082] ^. ^ = ∬ ^ ^ ^ . ^^

[0083] where M B is a mass flux of momentum and where S is a section through which the compounds contained in the combustion chamber 4 are discharged by the nozzle outside 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 section through which the compounds contained in the combustion chamber 4 are discharged outside the burner 3 following the combustion of the fourth stage. The section S is defined by the lips 11 of the burner 3.

[0084] With reference to Figure 5, the mass flux MB of momentum decreases for a proportion of hydrogen which increases during combustion determined by a constant richness ^. Curve (a) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel comprising only methane, for a richness ^ equal to 0.69. Curve (b) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel comprising 90% methane and 10% hydrogen, for a richness ^ equal to 0.69. Curve (c) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel comprising 80% methane and 20% hydrogen, for a richness ^ equal to 0.69. Curve (d) illustrates the mass flux MB as a function of the total fuel flow rate, the fuel comprising 70% methane and 30% hydrogen, for a richness ^ equal to 0.69. Curve (e) illustrates the mass flux M Bas a function of the total fuel flow rate, the fuel comprising only dihydrogen, for a richness ^ equal to 0.69.

[0085] The mass flow MB of momentum is defined by the following equation:

[0086] [Math 8]

[0087] ^ ^ = ^ ^ . ^ ^ = ^ ^ . ^

[0088] where Q B is the mass flow rate of compounds discharged outside burner 3, U B is the speed of the compounds evacuated outside the burner 3 and P B is the pressure in the combustion chamber 4.

[0089] Thus, the pressure P B in the combustion chamber 4 makes it possible to control the stretching of the filaments 8 so that the mineral fibers 1 formed have thermal and / or acoustic insulation characteristics. Preferably, during the fourth step 304, the pressure P Bin 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). Thus, it is possible to manufacture mineral fibers 1 having a micronaire of between 3 L / min and 24 L / min, in particular between 6 L / min and 20 L / min, using at least partly dihydrogen as fuel. The rotation speed of the plate may be greater than 2000 rpm. The fiber drawn by the plate may be less than 1 kg per day and per orifice 7 of the plate 6, and in particular less than 0.6 kg per day and per orifice 7 of the plate 6.

[0090] 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 may 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 3 hours.

[0091] 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 makes it possible to subject the plate to a mass flow MB equal to 18.9 Kg.m / s. 2by controlling a pressure PB in the combustion chamber 4 equal to 6002 Pa (612 mm CE).

[0092] The installation may comprise a control unit. The control unit may be configured to control the first flow rate of the first fluid and the second flow rate of the second fluid 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). Thus, the installation makes it possible to manufacture mineral fibers 1 having a micronaire of between 3 L / min and 24 L / min, in particular between 6 L / min and 20 L / min, using at least partly dihydrogen as fuel. The PB pressure can be calculated according to a predetermined model from the first flow rate and the second flow rate. The PB pressure can also be measured by a pressure sensor.The pressure sensor may be chosen from a pitot tube and a sensor arranged on the lips of the burner configured to emit a signal representative of the pressure in the combustion chamber.

[0093] 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).

[0094] The plate has a diameter DA and the nozzle has a cross-section of diameter DT. Due to the pressures PB in the combustion chamber 4 previously defined, an average quantity of movement of the compounds through the section of the nozzle during the fifth stage can be between 2π.DT.1961.(DA+DT) and 2π.DT.7354.(DA+DT), in particular between 2π.DT.4413.(DA+DT) and 2π.DT.7355.(DA+DT) and preferably between 2π.DT.5393.(DA+DT) and 2π.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 quantity of movement of the compounds through the section of the nozzle during the fifth stage can be between 38.7 kg.ms -2 and 154 kg.ms -2 , in particular between 87.0 kg.ms -2 and 145 kg.ms- 2 and preferably between 106 kg.ms -2 and 126 kg.ms -2 . For a diameter DT equal to 7.7 mm and for a diameter DA of the plate equal to 600 mm, an average quantity of movement of the compounds through the section of the nozzle during the fifth stage can be between 57.7 kg.ms -2 and 231 kg.ms -2 , in particular between 130 kg.ms -2 and 216 kg.ms -2 and preferably between 159 kg.ms -2 and 187 kg.ms -2.

[0095] Combustion richness

[0096] With reference to Figure 6, the richness ^ 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, in particular between 0.50 and 0.80 and preferably between 0.60 and 0.70. Thus, it is possible to compensate for a reduction in the mass flow density M Bdriven by the use of dihydrogen in the combustion by a higher proportion of second fluid 10 injected into the chamber 4. This makes it possible to implement a combustion in which dihydrogen is used as fuel while producing a mass flux density MB sufficient to stretch the filaments 8 formed by centrifugation. For richness values ​​below 0.40, the stability of a flame in the combustion chamber 4 during combustion is not ensured. For richness values ​​above 0.90, the mass flux density MB is too small to stretch the filaments 8 so as to form the mineral fibers 1, and fuel is present in the evacuated compounds, which is polluting. Figure 6 illustrates mass flux densities M Bas a function of the richness ^ for a molar ratio between dihydrogen and methane equal to 0.43. The richness ^ of the combustion reaction of the fourth step 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.

[0097] Temperature of a lip 11 of the burner 3

[0098] With reference to FIG. 7, at least one lip 11 defines a limit between the nozzle 5 and the exterior of the burner 3. A temperature of the lip 11 can be calculated as a function of the reactants introduced into the combustion chamber, considering in particular the reaction equations presented previously and the molar enthalpies of the different reactants and products involved in the reaction. Curve (f) illustrates the temperature of the lip 11 as a function of the richness ^ of the combustion reaction for a zero dihydrogen volume fraction and for a methane volume fraction equal to 1.Curve (g) illustrates the temperature of lip 11 as a function of the richness ^ 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. Curve (h) illustrates the temperature of lip 11 as a function of the richness ^ 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. Curve (i) illustrates the temperature of lip 11 as a function of the richness ^ 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 ^ of the combustion reaction for a volume fraction of dihydrogen equal to 1 and for a volume fraction of methane equal to zero.

[0099] During the fourth step 304, a temperature measured on the lip 11 may 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 richness may be adjusted so that the temperature measured on the lip 11 is within the ranges defined previously. Preferably, a richness ^ 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, in particular between 0.50 and 0.80 and preferably between 0.60 and 0.70, and a temperature measured on the lip 11 may 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 in fact 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 step 304.

[0100] Flame stability

[0101] With reference to FIG. 8, a composition of the first fluid 9 and a composition of the second fluid 10 define a flame speed Sf during the fourth combustion step 304. “Flame speed” means the speed of extension of a flame front during the combustion reaction. The flame speed depends on the consumption speed of the fuel and the oxidant during the combustion reaction.The first fluid 9 and the second fluid 10 may be mixed, preferably in the burner 3, before being introduced into the combustion chamber 4 so as to form a mixture. The mixture may be injected into the combustion chamber 4 during the second step 302 and during the third step 303. An average speed U of the mixture during its injection into the combustion chamber 4 may be greater than or equal to the flame speed S. f. Thus, it is possible to avoid a flashback during the combustion reaction. Indeed, if the flame speed Sf is higher than the average speed U, the flame moves towards the source of the mixture, leading to risks of explosion or degradation of the burner.

[0102] Initial pressure of the first fluid 9

[0103] The first fluid 9 and the second fluid 10 may be mixed, preferably in the burner 3, before being injected into the combustion chamber 4. The mixture injected into the combustion chamber 4 may have a pressure greater than 102000 Pa and preferably greater than 103000 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 temperature of the flame, to reduce the production of carbon dioxide.

[0104] Mixing of the first fluid 9 and the second fluid 10

[0105] The first fluid 9 and the second fluid 10 may be mixed in the burner 3 before being introduced into the combustion chamber 4. Thus, it is possible for the compounds of the first fluid 9 and the second fluid 10 to be distributed homogeneously in the combustion chamber 4 while avoiding a risk of combustion outside the burner 3 potentially caused by a mixture of the first fluid 9 and the second fluid 10 upstream of the burner 3.

[0106] With reference to FIG. 9, the burner 3 may comprise an injector 12. The injector 12 comprises a first fluid inlet 9, a second fluid inlet 10, a mixing pipe 13 fluidically connected to the first fluid inlet 9 and to the second fluid inlet 10. A lateral pipe 24 fluidically connects the first fluid inlet 9 to the mixing pipe 13.The injector 12 comprises an outlet 28 separating the mixing pipe 13 from the combustion chamber 4.

[0107] The geometry of the injector 12 is configured so that, during an 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 portion of the mixing pipe 13 in the same main flow direction 14 and so as to present a rotation of the second fluid 9 relative to the first fluid 10 around an axis oriented in the main 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 previously defined. This makes it possible to increase the stability of the flame during combustion. Indeed, it may be advantageous to implement the process in a so-called "lean" regime, i.e. for a richness lower than 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 the first fluid 9 and the second fluid 10, which may cause instability of the flame.

[0108] The injector 12 may comprise an angular deflection element 15 adapted to generate a swirling flow of the first fluid 9 and / or the second fluid 10 in the mixing pipe 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 pipe 13 in the same main flow direction 14 and so as to present a rotation of the second fluid 9 relative to the first fluid 10 around an axis oriented in the main flow direction 14.The angular deflection element 15 may be adapted to generate a swirling flow of the first fluid 9 or the second fluid 10 in the mixing conduit 13.

[0109] With reference to Figure 12, Figure 13 and Figure 14, the angular deflection element 15 may have a swirl number S which satisfies the equation S = 2 / 3 tan(ψ), ψ being the angular deflection angle of the flow of first fluid 9 and / or second fluid 10 after passing through the injector 15. The swirl 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.

[0110] The intensity of the rotary movement of the flow is characterized by the value of the vortex number S at the outlet of injector 12.The swirl number S, also called "swirl number" in English, defines the ratio between the tangential and axial momentum fluxes. It can be defined by the following equation:

[0111] [Math. 9]. where U and W are the axial and tangential components of the mean flow velocity, respectively, and R eis the radius of the mixing pipe 13. This swirl number S is approximated by the formula S = 2 / 3 tan ψ.

[0113] Increasing the swirl number S makes it possible to reduce the flame height and increase the flame opening. A wide flame opening makes it possible to limit the number of injectors arranged around the periphery of the combustion chamber 4, while still allowing homogeneous heating of the latter.

[0114] With reference to FIG. 10 and FIG. 11, the angular deflection element 15 may be formed, at least in part, by a ring arranged coaxially with the main flow direction 14. The ring may be removable.The ring may comprise a pipe adapted to allow the introduction of the swirling flow of first fluid 9 and / or second fluid 10 into the mixing pipe 13 of the injector 12 with an angular deflection angle ψ, the value of which is preferably between 10° and 80°, in particular between 20° and 70°, still preferably between 30° and 60°, still 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 thus possible to reduce the quantity of fuel to be injected, for the same quantity of oxidant involved in the combustion. The pipe adapted to allow the introduction of the swirling flow may form a part of the lateral pipe 24.

[0115] The angular deflection element may be a set of deflectors arranged in the mixing pipe 13 so as to rotate the flow of the first fluid 9 and the second fluid 10 along an axis following the main direction 14.

[0116] With reference to FIG. 10, the burner 3 is configured to separately supply the injector 12 with first fluid 9 and second fluid 10. The burner 3 may comprise a first inlet 26 for first fluid 9. The injector 12 may comprise an axial pipe 25 fluidically connecting the first inlet 26 to the mixing pipe 13. The burner 3 may comprise a second inlet 27 for second fluid 10. The second inlet 27 may be connected to the lateral pipe 24. The mixture between the first fluid 9 and the second fluid 10 is implemented in the mixing pipe 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.

[0117] With reference to FIG. 11, a wall of the lateral conduit 24 may have a frustoconical shape, the frustoconical shape having a main axis along the main direction 14. The diameter of the frustoconical shape may decrease along the main direction 14. Thus, it is possible to avoid a separation of the boundary layer of the swirling flow, in order to reduce the risks of the appearance of unwanted turbulence.

[0118] The second fluid 10 may be preheated, preferably at least by 5°C, before being injected into the burner 3. The preheating of the second fluid 10 may be implemented by recovering heat from the gases resulting from the combustion of the fourth step 304 and / or heat from the glass melting furnace.

[0119] The swirling flow generated in the mixing pipe 13 causes a recirculation of the fluids in the combustion chamber 4. The recirculation allows the flame generated during combustion to cling near the outlet of the injector in the combustion chamber 4. The clinging of the flame is favored by the presence of toroidal recirculation zones which bring a portion of the burnt gases back to the outlet of the injector, which causes a preheating of the gases coming from the injector 12. The flame being more stable, it is thus possible to reduce the quantity of fuel used for combustion without risking blowing out the flame.

[0120] The axial pipe 25 may have an outlet in the mixing pipe 13. The distance between the outlet of the axial pipe 25 and between 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 efficiency of the mixture. In addition, since the distance is strictly greater than zero, it is possible to limit the wear of the injector caused by a high combustion temperature. 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.

[0121] The outlet of the injector 12 may have a straight section. By "straight section", it is meant that the outlet of the injector 12 is formed by the wall of the mixing pipe 13 at the same point of the main direction 14. Indeed, the inventors have found that the beveled cutting of an outlet of an injector, as practiced in the state of the art, opposes a swirling circulation of the oxidant / fuel mixture and therefore reduces the beneficial technical effects linked thereto.Conversely, cutting the injector outlet along a straight section makes it possible to increase the stability of the flame during combustion.

[0122] The combustion chamber 4 is at least formed by one wall. The wall comprises a distal portion. The outlet 28 may be arranged in the center of the distal portion relative to the main axis X. Thus, the outlet is arranged equidistant from the upper and lower walls of the combustion chamber 4, which, due to gas recirculation, makes the flame more homogeneous and more stable.

[0123] A section of the outlet 28 may have a suitable diameter determined by the stabilization distance between the flame and the outlet 28. The smaller the diameter, the greater the speed of the flow of the mixture at the outlet 28, which increases the stabilization distance of the flame. The flame is then said to be "lifted". Beyond a certain ejection speed value, the flame is said to be "blown".On the contrary, the larger the diameter, the smaller the flow speed at the outlet 28. Below a determined flow speed of the mixture at the outlet 28, the flame risks stabilizing inside the injector 12, which is to be avoided.

[0124] The burner 3 may comprise several injectors 12. The burner 3 may comprise a distribution ring for the first fluid 9 and / or the second fluid 10 in the injectors 12. The ring may comprise inlets uniformly distributed around its periphery. The number of inlets may be equal to the number of injectors. Thus, the flow of fluid may be homogeneous in the injectors 12. Increasing the number of inlets of the ring makes it possible to increase the homogeneity of the fluid distribution in the injectors.

Claims

Claims

1. A method of manufacturing mineral fibers (1) by 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 fiberizing plate (6) having orifices (7), adapted to receive a molten mineral material, and adapted to form filaments (8) of the mineral material from the orifices (7) by centrifuging the plate (6), the method comprising at least: - a first step of manufacturing the filaments (8), - a second step 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 step of injecting a second fluid (10) into the combustion chamber (4) at a second flow rate, the second fluid (10) having a volume fraction oxygen greater than 0.10,- a fourth step of combustion of the fuel and oxygen introduced into the combustion chamber (4) during the second step and the third step, - a fifth step of drawing the filaments (8), the nozzle (5) being 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 during the first step so as to form the mineral fibers (1), the method being characterized in that the fuel comprises dihydrogen, a volume fraction of dihydrogen in the first fluid (9) being greater than 0.05, and in that during the fourth step, a pressure P, B 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, in the fourth step, a pressure P Bin 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 ^ 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. Method according to one of claims 1 to 3, wherein the fuel comprises an organic compound, in particular methane.

5. Method according to one of the preceding claims, wherein a lip (11) defines a boundary between the nozzle (5) and the exterior 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. Method according to 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 Sf during the fourth combustion step, 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 step and during the third step, 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 S. f.

7. Method according to 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. Method according to 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. Method according to 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) connected fluidly to the first fluid inlet (9) and to the second fluid inlet (10), and comprising an outlet fluidly connecting the mixing duct (13) to the combustion chamber (4), the geometry of the injector (12) being configured so that, during an 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 portion of the mixing duct (13) in the same main flow direction (14) and so as to present a rotation of the second fluid (9) relative to the first fluid (10) around an axis oriented in the main flow direction (14).

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

11. Method according to 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).

13. Installation (2) for the manufacture of mineral fibers (1), the installation 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 fiberizing plate (6) having orifices (7), adapted to receive a molten mineral material, and adapted to form filaments (8) of the mineral material from the orifices (7) by centrifuging the plate (6), the burner (3) comprising: - a first inlet (26) configured to receive a first fluid (9) at a first flow rate, the first fluid (9) comprising a fuel, the fuel comprising dihydrogen, a volume fraction of dihydrogen in the. first fluid (9) being greater than 0.05, the first inlet (26) being fluidically connected to the combustion chamber (4), - a second inlet (27), configured to receive a second fluid (10) at a second flow rate, the second fluid (10) having a volume fraction of oxygen greater than 0.10, the second inlet (27) being fluidically connected to the combustion chamber (4), the installation comprising a control unit configured to control the first flow rate of first fluid and the second flow rate of second fluid so that the pressure PB in the combustion chamber is between 1961 Pa (200 mm CE) and 7845 Pa (800 mm CE).

14. Installation according to claim 13, comprising an injector (12), the injector (12) comprising a first fluid inlet (9), a second fluid inlet (10), a mixing conduit (13) fluidically connected to the first fluid inlet (9) and to the second fluid inlet (10),and comprising an outlet fluidly connecting the mixing duct (13) to the combustion chamber (4), the first inlet (26) of the burner (3) being fluidly connected to the first fluid inlet (9) of the injector (12), the second inlet (27) of the burner (3) being fluidly connected to the second fluid inlet (10) of the injector (12), the geometry of the injector (12) being configured so that, during an 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 portion of the mixing duct (13) in the same main flow direction (14) and so as to present a rotation of the second fluid (9) relative to the first fluid (10) around an axis oriented in the main flow direction (14).,

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