Installation for manufacturing mineral fibres by centrifugation

Abstract

The invention relates to an installation (23) for manufacturing mineral fibres by centrifugation, comprising: - a first flow meter (28) suitable for measuring a first value of a fuel flow rate supplying a combustion chamber (4), - a second flow meter (29) suitable for measuring a second value of the fuel flow rate supplying the combustion chamber (4), the second flow meter being calibrated differently from the first flow meter, and - a control unit (30) configured to determine whether the fuel (9) supplying the combustion chamber (4) is a first fuel or a second fuel, and to control a fuel flow rate regulation valve (33) based on said determination.

Description

[0001] DESCRIPTION

[0002] TITLE: CENTRIFUGING MINERAL FIBER MANUFACTURING PLANT

[0003] FIELD OF INVENTION

[0004] The invention relates to an installation for manufacturing mineral fibers by centrifugation, and a process for manufacturing mineral fibers by centrifugation. The installation or the process can be applied, in particular, to the manufacture of glass wool.

[0005] STATE OF THE ART

[0006] In a mineral fiber manufacturing plant using centrifugal spinning, molten mineral material is fed into a fiber-forming plate. The molten mineral material is then propelled by centrifugal force through a perforated wall of the fiber-forming plate to create filaments of material.

[0007] The installation includes a combustion chamber configured to be supplied with fuel and oxidizer, and to generate a directed gas flow to heat the wall of the fiber-drawing plate and draw the filaments of material exiting the orifices. The fuel used is generally natural gas, such as methane. The oxidizer used is generally air.

[0008] Under the action of the gaseous drawing flow, the filaments are stretched, then break in such a way as to form mineral fibers.

[0009] The temperature and flow rate of the drawing gas affect the length and diameter of the resulting mineral fibers. These temperatures and flow rates are dependent on the temperature and pressure in the combustion chamber.

[0010] Thus, during manufacturing, the natural gas flow and the air flow supplying the combustion chamber are controlled to maintain a desired temperature and pressure in the combustion chamber.

[0011] To this end, a control unit operates a natural gas flow control valve and an air flow control valve to adjust the natural gas and air flow injected into the combustion chamber. It would be desirable to be able to change the fuel source, for example to supply the combustion chamber with biogas.

[0012] However, biogas is not always available in large quantities. Furthermore, biogas has a very different composition from natural gas. Finally, the composition of biogas varies considerably depending on the duration and quality of the fermentation process used to produce it.

[0013] Therefore, it is not possible to easily substitute biogas for natural gas to power the combustion chamber.

[0014] SUMMARY OF THE INVENTION

[0015] One aim of the invention is to allow the alternating use of a first fuel and a second fuel to supply the combustion chamber in a mineral fiber manufacturing installation by centrifugation, without the need to reprogram the control unit.

[0016] This objective is achieved within the framework of the present invention by means of a mineral fiber manufacturing installation by centrifugation, comprising: - a fiber-forming plate adapted to receive molten mineral material, the fiber-forming plate comprising a wall having orifices, and being adapted to be driven in rotation around a main axis, to cause a flow of molten mineral material through the orifices, so as to form filaments of material at the outlet of the orifices,

[0017] - a burner comprising a combustion chamber designed to be supplied with fuel and oxidizer, and to generate, through a combustion reaction between the fuel and the oxidizer, a directed gaseous flow for drawing, to heat the wall of the fiber-drawing plate and draw the filaments of material exiting the orifices,

[0018] - a first flow meter designed to measure an initial value of the fuel flow rate supplying the combustion chamber,

[0019] - a second flow meter specifically designed to measure a second value of the fuel flow rate supplying the combustion chamber, the second flow meter being calibrated differently from the first flow meter,

[0020] - a control unit configured for:

[0021] determine whether the fuel feeding the combustion chamber is a first fuel or a second fuel different from the first fuel, control a fuel flow control valve and an oxidant flow control valve, from a temperature setpoint value in the combustion chamber, a pressure setpoint value in the combustion chamber and a fuel flow value, the fuel flow value being the first fuel flow value when the fuel is the first fuel, and the fuel flow value being the second fuel flow value when the fuel is the second fuel.

[0022] Thanks to the use of the second flow meter, calibrated differently from the first flow meter, the fuel flow value used by the control unit takes into account the composition of the fuel that is used to feed the combustion chamber.

[0023] In this way, there is no need to modify or reprogram the control unit.

[0024] The proposed installation may also have the following characteristics:

[0025] In one embodiment, the installation includes

[0026] a distribution valve, movable between a first position in which the distribution valve connects the combustion chamber to a first source of the first fuel, and a second position in which the distribution valve connects the combustion chamber to a second source of the second fuel, such that in the first position of the distribution valve, the fuel supplying the combustion chamber is the first fuel and in the second position of the distribution valve, the fuel supplying the combustion chamber is the second fuel, and

[0027] a position sensor designed to generate a position signal indicating whether the distribution valve is in the first or second position, and the control unit determines whether the fuel feeding the combustion chamber is the first or second fuel from the position signal.

[0028] In one embodiment, the first flow meter and the second flow meter are arranged downstream of the distribution valve.

[0029] In one embodiment, the installation includes a first fuel supply conduit to the combustion chamber, the distribution valve being movable between a first position in which the distribution valve connects the first conduit to the first source of the first fuel, and a second position in which the distribution valve connects the combustion chamber to a second source of the second fuel, the first flow meter being connected to the first conduit and the second flow meter being connected to the first conduit.

[0030] In some embodiments, the first fuel feeding the combustion chamber is in a gaseous or liquid state.

[0031] When the first fuel is in a gaseous state, the first fuel comprises at least one of the following fuels: natural gas, biogas, dihydrogen, propane, butane, ammonia, a mixture of gases such as a mixture of dihydrogen, carbon monoxide, carbon dioxide and methane.

[0032] When the first fuel is in liquid form, the first fuel comprises at least one of the following fuels: ammonia, ethanol.

[0033] The second fuel is different from the first fuel.

[0034] The second fuel has a different composition than the first fuel.

[0035] In some embodiments, the second fuel supplying the combustion chamber is in a gaseous or liquid state.

[0036] When the second fuel is in a gaseous state, the second fuel comprises at least one of the following fuels: natural gas, biogas, dihydrogen, propane, butane, ammonia, a mixture of gases such as a mixture of dihydrogen, carbon monoxide, carbon dioxide and methane.

[0037] When the second fuel is liquid, the first fuel includes at least one of the following fuels: ammonia, ethanol.

[0038] In some embodiments, the first fuel is in a gaseous state and the second fuel is in a gaseous state.

[0039] In some embodiments, the primary fuel is, for example, natural gas.

[0040] In some embodiments, the second fuel is, for example, biogas. In one embodiment, the control unit includes a PID controller.

[0041] In one embodiment, the first flow meter and the second flow meter are calibrated such that for the same mass flow rate of fuel, the ratio between the second value of fuel flow measured by the second flow meter and the first value of fuel flow measured by the first flow meter is equal to the ratio between a second lower calorific value of the second fuel and a first lower calorific value of the first fuel.

[0042] The invention also relates to a process for manufacturing mineral fibers by centrifugation, comprising the steps of:

[0043] - to receive molten mineral material in a fiber-forming plate comprising a wall with orifices,

[0044] - to rotate the fiber-forming plate around a main axis, in order to cause the molten mineral material to flow through the orifices, so as to form filaments of material at the outlet of the orifices,

[0045] - to supply a burner combustion chamber with a fuel and an oxidizer, and generate, through a combustion reaction between the fuel and the oxidizer, a directed gaseous flow to heat the wall of the fiber-forming plate and stretch the filaments of material exiting the orifices, - to measure an initial value of the fuel flow rate supplying the combustion chamber using a first flow meter,

[0046] - measure a second value of the fuel flow rate feeding the combustion chamber using a second flow meter, calibrated differently from the first flow meter,

[0047] - determine whether the fuel supplying the combustion chamber is a primary fuel or a secondary fuel different from the primary fuel, - control a fuel flow control valve and an oxidizer flow control valve, based on a temperature setpoint value in the combustion chamber, a pressure setpoint value in the combustion chamber and a fuel flow rate value, the fuel flow rate value being:

[0048] the first value of the fuel flow rate when the fuel is the first fuel, and the second value of the fuel flow rate when the fuel is the second fuel.

[0049] In one implementation method, the process includes the following steps:

[0050] - acquire a position signal indicating whether a distribution valve is:

[0051] in a first position in which the distribution valve connects the combustion chamber to a first source of the first fuel, so that in the first position of the distribution valve, the fuel feeding the combustion chamber is the first fuel, or

[0052] in a second position in which the distribution valve connects the combustion chamber to a second source of the second fuel, so that in the second position of the distribution valve, the fuel supplying the combustion chamber is the second fuel,

[0053] in which the step of determining whether the fuel feeding the combustion chamber is the first fuel or the second fuel is implemented from the position signal.

[0054] The first fuel is, for example, natural gas.

[0055] The second fuel is, for example, biogas.

[0056] In one embodiment, the process includes a preliminary step of calibrating the first flow meter and the second flow meter such that for the same mass flow rate of fuel, the ratio between the second value of fuel flow measured by the second flow meter and the first value of fuel flow measured by the first flow meter is equal to the ratio between a second lower calorific value of the second fuel and a first lower calorific value of the first fuel.

[0057] The invention further relates to mineral fibers obtained by a process of manufacturing mineral fibers by centrifugation as defined above.

[0058] PRESENTATION OF THE DRAWINGS

[0059] Other features and advantages will become clearer from the following description, which is purely illustrative and not exhaustive and should be read in conjunction with the attached figures, including:

[0060] - Figure 1 schematically represents a device for manufacturing mineral fibers according to a possible embodiment of the invention; - Figure 2 schematically represents a mineral fiber manufacturing installation comprising the mineral fiber manufacturing device of Figure 1.

[0061] - Figure 3 schematically represents a control unit of the mineral fiber manufacturing installation.

[0062] DETAILED DESCRIPTION OF A METHOD OF IMPLEMENTATION

[0063] In Figure 1, the mineral fiber manufacturing device 2 comprises a fiber-laying 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 about the principal axis X by a motor (not shown). The shaft 17 is hollow, forming a channel 18 through which molten mineral material can flow. The mineral material is, for example, glass.

[0064] In operation, device 2 is arranged so that the principal axis X is vertical in a terrestrial frame of reference and the mineral material flows in the conduit 18 under the effect of gravity to be collected in the basket 16. The conduit 18 is fluidly connected to a molten mineral material supply at one of its ends. The plate 6 and the basket 16 are fixedly mounted at the other end of the shaft 17 by means of a flange 19.

[0065] Plate 6 comprises a first annular wall 20 and a veil 21. The first annular wall 20 is pierced by a plurality of orifices 7. The veil 21 connects the first annular wall 20 to the tulip 19. The veil 21 forms an upper part of the fiber plate 6.

[0066] The basket 16 comprises a second annular wall 22. The second annular wall 22 is pierced by a plurality of orifices 13. The basket 16 is mounted inside the fiber plate 6. Thus, the fiber plate 6 surrounds the basket 16. In another variant, the plate is without a basket and is called a bottom plate.

[0067] In operation, the shaft 17, the fiber plate 6 and the basket 16 are driven together in rotation around the main axis X. The molten mineral material is poured into the conduit 18 of the shaft 17 from the mineral material feed and flows in the conduit 18 to the basket 16 under the effect of gravity. Under the centrifugal effect generated by the rotation of the assembly comprising the shaft 17, the plate 6 and the basket 16, the molten mineral material is projected onto the second annular wall 22, then the molten mineral material flows through the second annular wall 22, via the plurality of orifices of the second annular wall 22 before being projected onto the first annular wall 20. The molten mineral material then flows through the first annular wall 20, via the plurality of orifices 7 of the first annular wall 20 so as to form filaments 8 of material at the exit of the orifices 7.

[0068] When the molten material is projected onto the first annular wall 20, a reservoir of material is formed in the fiber-forming plate 6. This reservoir of material continuously feeds the plurality of orifices 7 in the first wall 20 to form the filaments 8.

[0069] Device 2 includes an annular burner 3. The annular burner 3 is configured to generate a drawing gas flow to draw the filaments 8 produced at the outlet of the orifices 7 of the first wall 20. 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 11 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.

[0070] The gas flow from the drawing process is produced by combustion in the annular burner 3. The annular burner 3 comprises 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 fuel 9 and oxidizer 10. The combustion reaction is initiated in the combustion chamber 4.

[0071] For this purpose, the burner 3 may include an injector 12 suitable for connection to an oxidizer source and a fuel source, and for injecting the fuel 9 and the oxidizer 10 into the combustion chamber 4. In the example illustrated in Figure 1, the injector 12 is configured to mix the fuel 9 and the oxidizer 10 before their introduction into the combustion chamber 4. In other words, the injector 12 is configured to form a mixture of fuel 9 and oxidizer 10 and inject the mixture into the combustion chamber 4. Alternatively, the installation does not include the injector 12. In this case, the device 2 includes a mixer connected to the oxidizer source and the fuel source and configured to mix the fuel 9 and the oxidizer 10, and a mixture supply line connected to the mixer and the combustion chamber for injecting the fuel and oxidizer mixture into the combustion chamber 4.

[0072] In Figure 2, the mineral fiber manufacturing installation 23 includes the mineral fiber manufacturing device 2 of Figure 1, a first source 24 of a first fuel, a second source 25 of a second fuel, an oxidant source 26, a distribution valve 27, a first flow meter 28, a second flow meter 29 and a control unit 30.

[0073] The first fuel is, for example, natural gas, that is, a fossil gas, generally comprising 70 to 90% methane by volume. The first fuel thus has a basic composition. The first fuel has a lower calorific value.

[0074] The lower heating value (LHV) of a fuel refers to the amount of heat released by the complete combustion of a unit of fuel, assuming no water vapor is condensed and no heat is recovered. LHV is measured in megajoules per kilogram (MJ / kg) or kilowatt-hours per cubic meter (kWh / m³). 3 ).

[0075] The second fuel is, for example, biogas, which is gas produced by the fermentation of organic matter. The composition of biogas depends on the duration and quality of the fermentation process used to produce it. Biogas typically contains 50 to 70% methane by volume. Thus, the second fuel has a different composition than the first. Furthermore, the second fuel has a lower heating value (LHV), which may differ from the LHV of the first fuel. For example, the LHV of the second fuel is lower than the LHV of the first fuel.

[0076] Advantageously, the difference between the LHV of the first fuel and the LHV of the second fuel is greater than or equal to 1 kWh / m² 3 .

[0077] Other fuels besides biogas can be used as a second fuel, such as propane.

[0078] The oxidizer is, for example, air. In the example illustrated in Figure 2, the installation 23 includes a first conduit 31 for supplying fuel to the combustion chamber 4 of the fiber manufacturing device 2 and a second conduit 32 for supplying oxidizer to the combustion chamber 4.

[0079] The distribution valve 27 is movable between a first position in which it connects the first conduit 31 to the first source 24 of the first fuel, and a second position in which it connects the first conduit 31 to the second source of the second fuel. The distribution valve 27 can be manually operated, electrically operated, or a combination of both.

[0080] In the case where the distribution valve 27 is manually operated, the passage of the distribution valve 27 from the first position to the second position, and vice versa, is controlled by a human operator.

[0081] In the case where the distribution valve 27 is electrically controlled, the passage of the distribution valve 27 from the first position to the second position, and vice versa, can be controlled by a control unit which may be the control unit 30. In this case, the control unit 30 is suitable for generating a control signal to selectively move the distribution valve 27 from the first position to the second position, and from the second position to the first position.

[0082] Thus, in the first position of the distribution valve 27, the fuel 9 feeding the combustion chamber 4 is the first fuel, and in the second position of the distribution valve 27, the fuel 9 feeding the combustion chamber is the second fuel.

[0083] The first flow meter 28 is designed to measure a first value of a fuel flow supplying the combustion chamber 4, and to generate a first measurement signal representative of the first measured flow value.

[0084] In the example illustrated in Figure 2, the first flow meter 28 is connected to the first conduit 31 and the fuel flow rate is the fuel flow rate circulating in the first conduit 31.

[0085] The second flow meter 29 is designed to measure a second value of the fuel flow rate supplying the combustion chamber 4, and to generate a second measurement signal representative of this second measured flow rate. The second flow meter is calibrated differently from the first flow meter 28. In the example illustrated in Figure 2, the second flow meter 29 is also connected to the first duct 31, and the fuel flow rate is the fuel flow rate circulating in the first duct 31.

[0086] Alternatively, it would be possible to connect each of the fuel sources 24 and 25 to the combustion chamber 4 by means of a respective fuel supply duct, and to connect each flow meter to a respective fuel supply duct.

[0087] Installation 23 also includes a fuel flow control valve 33, an oxidizer flow control valve 34, a temperature sensor 35, a pressure sensor 36 and a position sensor 37.

[0088] The fuel flow control valve 33 is designed to be controlled to vary the fuel flow circulating in the first conduit 31 and supplying the combustion chamber 4.

[0089] The oxidant flow control valve 34 is designed to be controlled to vary the oxidant flow circulating in the second conduit 32 and supplying the combustion chamber 4.

[0090] The temperature sensor 35 is designed to measure a temperature in the combustion chamber 4 and to generate a third measurement signal representative of the value of the temperature measured in the combustion chamber 4.

[0091] Temperature sensor 35 is, for example, a thermocouple.

[0092] The pressure sensor 36 is designed to measure pressure in the combustion chamber 4 and to generate a fourth measurement signal representative of the value of the pressure measured in the combustion chamber 4.

[0093] Pressure sensor 36 is, for example, a pressure gauge.

[0094] The position sensor 37 is designed to generate a position signal indicating whether the distribution valve 27 is in the first position or the second position.

[0095] The control unit 30 can be an industrial programmable logic controller (or "PLC").

[0096] The control unit 30 is configured to receive the first measurement signal, the second measurement signal, the third measurement signal and the fourth measurement signal, and to generate a first control signal to control the fuel flow control valve 33 and a second control signal to control the oxidizer flow control valve 32. More specifically, the control unit 30 is configured to generate the first control signal and the second control signal from the temperature value measured in the combustion chamber 4, the pressure value measured in the combustion chamber 4, a temperature setpoint value in the combustion chamber 4, a pressure setpoint value in the combustion chamber 4 and a value of the fuel flow rate supplying the combustion chamber 4.

[0097] Furthermore, in the example illustrated in Figure 2, the control unit 30 is also configured to receive the position signal generated by the position sensor 37.

[0098] Furthermore, control unit 30 is configured to execute the following steps:

[0099] - determine whether the fuel 9 supplying the combustion chamber 4 is the primary or secondary fuel,

[0100] - if the fuel is the first fuel, the fuel flow rate value used by the control unit 30 to generate the control signals is the first fuel flow rate value, and

[0101] - if the fuel is the second fuel, the fuel flow value used by the control unit to generate the control signals is the second fuel flow value.

[0102] In the example illustrated in Figure 2, the control unit 30 can determine whether the fuel feeding the combustion chamber 4 is the first fuel or the second fuel from the position signal generated by the position sensor 37, indicating the position of the distribution valve 27.

[0103] The second flow meter 29 is calibrated differently from the first flow meter 28, so that the value of the fuel flow used by the control unit 30 takes into account the composition of the fuel which is used to feed the combustion chamber 4.

[0104] For example, the first flow meter 28 and the second flow meter 29 are calibrated so that for the same mass flow rate of fuel circulating in the first conduit 31, the ratio between the second value of fuel flow measured by the second flow meter and the first value of fuel flow measured by the first flow meter is equal to the ratio between the second lower calorific value of the second fuel and the first lower calorific value of the first fuel.

[0105] As illustrated in Figure 3, the control unit 30 can include a first regulator 38, a second regulator 39 and a third regulator 40.

[0106] The first regulator 38 is, for example, a PID regulator. The first regulator is designed to calculate a fuel flow rate value F1* and an oxidizer flow rate value F2* from a setpoint temperature value T*, a setpoint pressure value P*, a measured temperature value T in the combustion chamber 4 and a measured pressure value P in the combustion chamber 4.

[0107] The setpoint temperature T* and setpoint pressure P* are chosen according to the length and diameter of the mineral fibers to be manufactured. The setpoint temperature T* is, for example, within a range of 1100°C to 1500°C. The setpoint pressure is, for example, within a range of 250 mml O₂ to 900 mml O₂ (i.e., between 2452 Pa and 8826 Pa).

[0108] The pressure in combustion chamber 4 is controlled primarily by the flow rate of oxidant injected into combustion chamber 4. Increasing the flow rate of oxidant increases the pressure in combustion chamber 4, while decreasing the flow rate of oxidant decreases the pressure in combustion chamber 4.

[0109] However, an increase in the flow rate of oxidizer injected into combustion chamber 4 can lead to a decrease in the combustion chamber temperature. Therefore, to maintain a suitable combustion chamber temperature, it is necessary to increase the fuel flow rate as the oxidizer flow rate increases, in order to maintain a constant combustion mixture.

[0110] The combustion efficiency refers to the ratio between the amount of oxidizer actually used and the theoretical amount of oxidizer required for complete (stoichiometric) combustion. The combustion efficiency (O) is calculated as follows:

[0111] Actual oxidizer

[0112] (J, > Actual fuel

[0113] Stoichiometric Oxidizer

[0114] Stoichiometric Fuel

[0115] where "Actual Oxidizer" and "Actual Fuel" denote the quantities of oxidizer and fuel actually used, and "Stoichiometric Oxidizer" and "Stoichiometric Fuel" denote the quantities of oxidizer and fuel required to achieve complete consumption of the oxidizer and fuel during combustion, the quantities being expressed in normo cubic meters (Nm³). 3), that is to say that these quantities are volumes measured under normal conditions of temperature and pressure (temperature at 0°C and pressure at 1 atmosphere, i.e. 101,325 Pascals).

[0116] If <t>> 1, then the mixture is rich (there is an excess of fuel).

[0117] If <t>< 1, then the mixture is lean (there is an excess of oxidizer).

[0118] If <t>= 1, then the mixture is stoichiometric.

[0119] Thus, the temperature in the combustion chamber is controlled primarily by the ratio between the fuel flow rate and the oxidant flow rate injected into the combustion chamber.

[0120] The first regulator 38 is configured such that the oxidant flow value F2* calculated by the first regulator 38 increases when the setpoint pressure value P* is greater than the pressure value P measured in the combustion chamber 4, and that the oxidant flow value F2* calculated by the first regulator 38 decreases when the setpoint pressure value P* is less than the pressure value P measured in the combustion chamber 4.

[0121] The first regulator 38 is also configured such that the ratio between the value of fuel flow F1* and the value of oxidant flow F2* calculated by the first regulator 38 increases when the value of setpoint temperature T* is greater than the value of temperature T measured in the combustion chamber 4, and that the ratio between the value of fuel flow F1* and the value of oxidant flow F2* calculated by the first regulator 38 decreases when the value of setpoint temperature T* is less than the value of temperature T measured in the combustion chamber 4.

[0122] The second controller 39 is designed to control the fuel flow control valve 33 based on the difference between the fuel flow value F1* calculated by the controller 38 and a measured fuel flow value. The measured fuel flow value is the fuel value F1 measured by the first flow meter 28 when the fuel is the first fuel, and the measured fuel flow value is the fuel value F1' measured by the second flow meter 29 when the fuel is the second fuel. The second controller 39 is configured to calculate a position P1 of the control valve 33 from this difference and generate the first control signal to operate the fuel flow control valve 33.

[0123] The third regulator 40 is designed to control the oxidizer flow control valve 34 based on the oxidizer flow value F2*. The third regulator 40 is configured to calculate a position P2 of the control valve 34 from this value, and to generate the second control signal to operate the oxidizer flow control valve 32.< / t> < / t> < / t>

Claims

DEMANDS 1. Installation (23) for the manufacture of mineral fibers by centrifugation, comprising: - a fiber-forming plate (6) adapted to receive molten mineral material, the fiber-forming plate (6) comprising a wall (20) having orifices (7), and adapted to be driven in rotation around a principal axis (X), to cause a flow of molten mineral material through the orifices (7), so as to form filaments of material (8) at the outlet of the orifices, - a burner (3) comprising a combustion chamber (4) suitable for being supplied with a fuel (9) and an oxidizer (10), and for generating by a combustion reaction between the fuel and the oxidizer, a directed gaseous flow of drawing to heat the wall (20) of the fiber-drawing plate (6) and to draw the filaments of material (8) at the exit of the orifices (7), - a first flow meter (28) suitable for measuring a first value of a fuel flow rate supplying the combustion chamber (4), - a second flow meter (29) designed to measure a second value of the fuel flow rate supplying the combustion chamber (4), the second flow meter being calibrated differently from the first flow meter, - a control unit (30) configured for: determine whether the fuel (9) feeding the combustion chamber (4) is a primary fuel or a secondary fuel different from the primary fuel, control a fuel flow control valve (33) and an oxidizer flow control valve (34), from a temperature setpoint value in the combustion chamber, a pressure setpoint value in the combustion chamber and a fuel flow value, the fuel flow value being the first fuel flow value when the fuel is the first fuel, and the fuel flow value being the second fuel flow value when the fuel is the second fuel.

2. Installation (23) according to claim 1, comprising: - a distribution valve (27), movable between a first position in which the distribution valve (27) connects the combustion chamber (4) to a first source (24) of the first fuel, and a second position in which the distribution valve (27) connects the combustion chamber (4) to a second source (25) of the second fuel, such that in the first position of the distribution valve (27), the fuel (9) supplying the combustion chamber (4) is the first fuel and in the second position of the distribution valve (27), the fuel (9) supplying the combustion chamber (4) is the second fuel, and - a position sensor (37) suitable for generating a position signal indicating whether the distribution valve (27) is in the first position or the second position, in which the control unit (30) determines whether the fuel (9) supplying the combustion chamber (4) is the first fuel or the second fuel from the position signal.

3. Installation (23) according to claim 2, wherein the first flow meter (28) and the second flow meter (29) are arranged downstream of the distribution valve (27).

4. Installation (23) according to any one of claims 1 to 3, wherein the first fuel is natural gas.

5. Installation (23) according to any one of claims 1 to 4, wherein the second fuel is biogas.

6. Installation (23) according to any one of claims 1 to 5, wherein the control unit (30) comprises a PID controller (38).

7. Installation (23) according to any one of claims 1 to 6, wherein the first flow meter (28) and the second flow meter (29) are calibrated such that, for the same mass flow rate of fuel, the ratio between the second fuel flow rate value measured by the second flow meter (29) and the first fuel flow rate value (28) measured by the first flow meter is equal to the ratio between a second lower calorific value of the second fuel and a first lower calorific value of the first fuel.

8. Process for manufacturing mineral fibers by centrifugation, comprising the steps of: - to receive molten mineral material in a fiber-forming plate (6) comprising a wall (20) having orifices (7), - to rotate the fiber-forming plate (6) around a main axis (X), to cause the molten mineral material to flow through the orifices (7), so as to form filaments of material (8) at the outlet of the orifices, - to supply a combustion chamber (4) of a burner (3) with a fuel (9) and an oxidizer (10), and to generate, by a combustion reaction between the fuel and the oxidizer, a directed gaseous flow of drawing to heat the wall (20) of the fiber-drawing plate (6) and to draw the filaments of material (8) at the exit of the orifices, - measure a first value of a fuel flow rate supplying the combustion chamber (4) using a first flow meter (28), - measure a second value of the fuel flow rate supplying the combustion chamber (4) using a second flow meter (29), calibrated differently from the first flow meter (28), - determine whether the fuel (9) supplying the combustion chamber (4) is a primary fuel or a secondary fuel different from the primary fuel, - control a fuel flow control valve (33) and an oxidizer flow control valve (34), based on a temperature setpoint in the combustion chamber, a pressure setpoint in the combustion chamber and a fuel flow rate value, the fuel flow rate value being: the first value of the fuel flow rate when fuel (9) is the first fuel, and the second value of the fuel flow rate when the fuel (9) is the second fuel.

9. A method according to claim 8, comprising the steps of: - acquire a position signal indicating whether a distribution valve (37) is: in a first position in which the distribution valve (37) connects the combustion chamber (4) to a first source (24) of the first fuel, so that in the first position of the distribution valve (37), the fuel (9) supplying the combustion chamber (4) is the first fuel, or in a second position in which the distribution valve (27) connects the combustion chamber (4) to a second source (25) of the second fuel, so that in the second position of the distribution valve (27), the fuel (9) supplying the combustion chamber (4) is the second fuel, in which the step of determining whether the fuel (9) feeding the combustion chamber (4) is the first fuel or the second fuel is implemented from the position signal.

10. A method according to any one of claims 8 and 9, wherein the first fuel is natural gas.

11. A method according to any one of claims 8 to 10, wherein the second fuel is biogas.

12. A method according to any one of claims 8 to 11, comprising a preliminary step of calibrating the first flow meter (28) and the second flow meter (29) such that for the same mass flow rate of fuel, the ratio between the second value of fuel flow measured by the second flow meter (29) and the first value of fuel flow measured by the first flow meter (28) is equal to the ratio between a second lower calorific value of the second fuel and a first lower calorific value of the first fuel (29).

13. Mineral fibers obtained by a process for manufacturing mineral fibers by centrifugation according to any one of claims 8 to 12.

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