PROCESS FOR ADJUSTING THE AMOUNT OF DILUTION WATER OF A BINDING COMPOUND, AND CORRESPONDING COMPUTING UNIT

Abstract

A process for manufacturing a mat of mineral fibers, wherein fibers are formed and a binding compound resulting from the mixture of a binder composition with dilution water is applied on the fibers, the fibers impregnated with the binding compound are collected on a perforated receiving device equipped with a fiber-receiving surface and, below the surface, at least one suction duct, and the mat is heat treated. The process includes determining an optimal amount of dilution water as a function of the humidity of the air in the fiberizing station, of the humidity of the intake air and of the intake air flow rate in the at least one suction duct, and of the desired amount of water in the mat at the outlet of the receiving chamber, and adjusting the amount of dilution water as a function of the optimal amount thus determined.

Claims

1. A process for adjusting an amount of dilution water of a binding compound intended to be applied on fibers in a fiberizing station of a plant for manufacturing a mat of mineral fibers, the manufacturing plant comprising a fiberizing station, comprising means for forming the fibers and means for applying, on said fibers, a binding compound resulting from the mixture of a binder composition with dilution water, a receiving chamber-O comprising a perforated receiving device equipped with a fiber-receiving surface and, below said fiber-receiving surface, at least one suction duct, means for heat treatment of the mat, the process comprising: determining humidity of ambient air in the fiberizing station, determining humidity of intake air and intake air flow rate in the at least one suction duct, determining an optimal amount of dilution water as a function at least of the humidity of the ambient air in the fiberizing station, of the humidity of the intake air and of the intake air flow rate in the at least one suction duct, and of a desired amount of water in the mat at an outlet of the receiving chamber, and adjusting the amount of dilution water as a function of said optimal amount thus determined.

2. The process as claimed in claim 1, wherein the fiberizing station comprises a plurality of members for heating or supplying air, water or other products, and the optimal amount of dilution water is determined by further taking into account the amount of usable water, resulting from one or more of said plurality of members.

3. The process as claimed in claim 2, wherein the amount of usable water is at least equal to the sum of the amount of water resulting from at least one burner and of the amount of water resulting from the binder composition.

4. The process as claimed in claim 2, wherein the amount of usable water is at least equal to the sum of the amount of water resulting from at least one burner, the amount of water resulting from the binder composition and the amount of water resulting from at least one device for supplying recycled intake air.

5. The process as claimed in claim 1, wherein the fiberizing station comprises a plurality of members for heating or supplying air, water or other products, and the optimal amount of dilution water is determined by further taking into account an amount of usable air, resulting from one or more of said plurality of members.

6. The process as claimed in claim 1, wherein the intake air flow rate in said at least one suction duct is maintained at a constant value.

7. The process as claimed in claim 1, wherein, in order to determine the humidity of the ambient air in the fiberizing station measurements of humidity of the air are carried out at various locations of the fiberizing station and an average of the values thus measured is computed.

8. The process as claimed in claim 1, wherein the adjustment of the amount of dilution water in the binding compound is carried out continuously during the manufacture of the mat of mineral fibers.

9. The process as claimed in claim 1, wherein the adjustment of the amount of water in the binding compound is carried out periodically or after each change of product.

10. A process for manufacturing a mat of mineral fibers, comprising: in a fiberizing station, forming fibers and applying a binding compound resulting from e a mixture of a binder composition with dilution water on said fibers, collecting the fibers impregnated with the binding compound in a receiving chamber comprising a perforated receiving device equipped with a fiber-receiving surface and, below said fiber-receiving surface, at least one suction duct, heat treating the mat, and the process further comprising a monitoring an amount of dilution water of a binding compound as claimed in the process of claim 1.

11. A unit for computing an amount of dilution water of a binding compound intended to be applied on fibers in a fiberizing station of a plant for manufacturing a mat of mineral fibers, the manufacturing plant comprising a fiberizing station, comprising means for forming the fibers and means for applying, on said fibers, a binding compound resulting from the mixture of a binder composition with dilution water, a receiving chamber comprising a perforated receiving device equipped with a fiber-receiving surface and, below said fiber-receiving surface, at least one suction duct, and means for heat treatment of the mat, the computing unit further comprising: means for determining humidity of ambient air in the fiberizing station, means for determining humidity of intake air and means for determining the intake air flow rate in the at least one suction duct, means for computing an optimal amount of dilution water as a function at least of the humidity of the ambient air in the fiberizing station, of the humidity of the intake air and of the intake air flow rate in the at least one suction duct, and of a desired amount of water in the mat at an outlet of the receiving chamber, and means for adjusting the amount of dilution water as a function of said optimal amount determined by said computing means.

12. A plant for manufacturing a mat of mineral fibers, comprising: a fiberizing station, comprising means for forming the fibers and means for applying, on said fibers, a binding compound resulting from the mixture of a binder composition with dilution water, a receiving chamber comprising a perforated receiving device equipped with a fiber-receiving surface and, below said receiving surface, at least one suction duct, means for heat treatment of the mat, and a computing unit as claimed in claim 11.

13. The process as claimed in claim 1, wherein the perforated receiving device is a perforated conveyor or a grid.

14. The process as claimed in claim 2, wherein the plurality of members include at least one burner and/or means for applying the binding compound and/or at least one blowing ring and/or air guns and/or at least one device for supplying fragments of recycled product and/or at least one device for supplying recycled intake air.

15. The process as claimed in claim 2, wherein the amount of usable water, resulting from one or more of said plurality of members is measured beforehand by tests or determined by computation.

16. The process as claimed in claim 5, wherein the plurality of members include at least one burner and/or means for applying the binding compound and/or at least one blowing ring and/or air guns and/or at least one device for supplying fragments of recycled product and/or at least one device for supplying recycled intake air.

17. The process as claimed in claim 5, wherein the amount of usable air, resulting from one or more of said plurality of members is measured beforehand by tests or determined by computation.

18. The process as claimed in claim 9, wherein the adjustment of the amount of water in the binding compound is carried out every hour.

19. The process as claimed in claim 10, wherein the perforated receiving device is a perforated conveyor or a grid.

20. The unit as claimed in claim 11, wherein the perforated receiving device is a perforated conveyor or a grid.

Description

[0088] The description refers to the appended drawings, in which:

[0089] FIG. 1 is a schematic view of a plant for manufacturing a mat of mineral fibers, according to a first exemplary embodiment of the invention,

[0090] FIG. 2A is a cross-sectional view along II of FIG. 1,

[0091] FIG. 2B is a detailed view of the part IIB of FIG. 2A,

[0092] FIG. 3 is a schematic view of a plant for manufacturing a mat of mineral fibers, according to a second exemplary embodiment of the invention.

[0093] FIG. 1 is a schematic view of a plant 10 for manufacturing a mat M of glass fibers according to a first exemplary embodiment, comprising, in the order of the manufacturing procedure, a fiberizing station 12, a forming station 14 and a drying oven 16.

[0094] The fiberizing station 12 comprises at least one fiberizing device 20, preferably a plurality of such devices 20a, . . . , 20n arranged in series, as illustrated in FIG. 1.

[0095] Such a fiberizing device 20 is illustrated in greater detail in FIGS. 2A and 2B.

[0096] To manufacture the fibers, the device 20 comprises a spinner 22, also known as a fiberizing spinner, capable of rotating at high speed about an axis A, which is in particular vertical, and comprising an annular wall 24 pierced by a plurality of orifices 26 and optionally a base. A molten glass stream, introduced into the spinner 22, is projected by the plurality of orifices 26 under the effect of the centrifugal force, creating a plurality of filaments.

[0097] Each fiberizing device 20 also comprises at least one annular burner 30 generating a high-temperature attenuating gas jet 32, substantially tangential to the annular wall 24 of the spinner 22, intended to heat and thin said filaments leaving the spinner, thus transforming them into fibers F.

[0098] Optionally, the fiberizing device 20 may also comprise a device for heating the lower part of the spinner in the form of a magnetic induction ring 34.

[0099] Each fiberizing device 20 further comprises a blowing ring or air ring 36 positioned below the burner 30, and intended to prevent a dispersion of the fibers too far from the axis of rotation A of the spinner 22.

[0100] Each fiberizing device 20 lastly comprises a device 40 for applying a binding compound on the fibers F. This application device 40 is typically in the form of an annular ring 42 bearing spray nozzles 44 and inside which ring the glass fibers F successively pass. The ring 42 is connected to a binding compound tank 46 and each spray nozzle 44 associated with this ring is configured to receive, on the one hand, an amount of the binding compound and, on the other hand, an amount of compressed air via an independent supply (not represented) in order to project the binding compound as the glass fibers pass by.

[0101] In the binding compound tank 46, a binder composition is mixed with a greater or lesser amount of dilution water resulting from a water tank 47 connected to the binding compound tank 46 via a water supply line 48 provided with adjustment means, typically a control valve 49.

[0102] The binder composition is an aqueous solution, the solids content of which is constant, typically of the order of 15% by weight. Its solids consist of chemical precursors intended to react via polymerization within the context of a heat treatment in the drying oven 16.

[0103] The amount of dilution water, for its part, is a parameter that can be adjusted by virtue of the adjustment means 49, thus making it possible to regulate the water content of the binding compound ultimately applied on the fibers F.

[0104] Optionally, the fiberizing device 20 may further comprise, downstream of the device 40 for applying the binding compound, air nozzles 38—also known as air guns—here represented schematically by arrows, that make it possible to distribute the fibers F. The distribution of the fibers F is adjusted if need be by modifying the orientation of the nozzles and the pressure of the air which results therefrom.

[0105] The glass fibers F of each fiberizing device 20 thus fall until they arrive at the forming station 14. There, they are collected in the form of a mat M in a receiving chamber 50, on a perforated conveyor 52. As illustrated in the figures, one or more suction ducts 54 (three ducts respectively 54a, 54b, 54c in the example represented in FIG. 1) are intended to create and maintain a negative pressure below the receiving surface 52a of the conveyor 52 receiving the mat M. For this, each suction duct 54 opens, via its “upstream” end, below the receiving surface 52a of the conveyor 52, and is connected to one or more extraction fans 56 (visible in FIG. 2A) generating the suction force. The air thus taken in is referred to as forming air or intake air.

[0106] The receiving chamber 50 is typically delimited by four walls, which are orthogonal in pairs: two front and rear fixed walls 58, 60, transverse to the transportation direction of the conveyor, and two lateral walls 62, 64—also known as hood walls—consisting of moving endless belts, of which the outer portions 62a, 64a are continuously cleaned by water. The inner surfaces 62b, 64b of the hood walls recover the dust and binder inside the receiving chamber 50. This dust is discharged during the cleaning of said surface to the outside when they pass to the outside via rotation.

[0107] It should be noted that, as a variant, the four walls of the receiving chamber may be formed of moving endless belts as defined above.

[0108] The mat M is then sent in the direction of the drying oven 16 forming a crosslinking station, in which it is simultaneously dried out and subjected to a specific heat treatment which gives rise to the polymerization (or “curing”) of the resin of the binder present at the surface of the fibers.

[0109] The mat M of mineral fibers is then subjected to [0110] a longitudinal cutting of its uneven edges, in the length direction, generally by means of saws, and [0111] a cutting in a transverse direction and optionally in the thickness direction (splitting), so as to obtain blocks that will then be able to be arranged either as sheets or as rolls, generally by means of a saw or of a guillotine, in order to form for example thermal and/or sound insulation panels or rolls.

[0112] In certain manufacturing plants, the uneven edges of the panels are recovered, ground, then reintroduced upstream into the process. The fiberizing station 12 may then, in addition to the foregoing, comprise one or more devices 68 for supplying fragments of recycled product: each device 68 for supplying fragments of recycled product is located for example between two fiberizing devices 20, preferably between two spinners 22, as illustrated in FIG. 3.

[0113] According to the invention, the manufacturing process comprises a step of computing the optimal amount of dilution water as a function of several parameters measured at different levels of the process and—for other parameters—computed or set beforehand.

[0114] This computation is carried out by a unit 70 for computing the optimal amount of dilution water, which unit 70 is connected to a plurality of measurement devices described subsequently, by means of which the following are determined: [0115] the humidity of the ambient air in the fiberizing station, [0116] the humidity of the intake air in the at least one suction duct, and [0117] the intake air flow rate in the at least one suction duct.

[0118] By using these measured data and other parameters of the process that are computed or set beforehand, the computing unit determines the optimal amount of dilution water by using an equation of the type:

[Math1]

D.sub.d=D.sub.m+D.sub.aa*(H.sub.aa−H.sub.ai)+C.sub.a*H.sub.ai−C.sub.e  (1)

where
D.sub.d is the mass flow rate of water to be added to the binding compound (in kg/h)
D.sub.m is the target mass flow rate of water desired in the moving mat at the outlet of the receiving chamber and upstream of the drying oven (in kg/h)
D.sub.aa is the mass flow rate of air taken in by the at least one suction duct (in kg/h)
H.sub.aa is the absolute humidity of the air in the at least one suction duct (kg of water/kg of dry air)
H.sub.ai is the average absolute humidity of the air in the fiberizing station (kg of water/kg of dry air)
C.sub.a is a value representative of the amount of air resulting from the members of the fiberizing station
C.sub.e is a value representative of the amount of water resulting from the members of the fiberizing station.

[0119] The absolute humidity of the ambient air in the fiberizing station 12 may be obtained by computation from the relative humidity and from the temperature of the air, measured using at least one relative humidity measuring device 72 and at least one temperature measuring device 74, which are positioned in a zone representative of the general hygrometry and temperature conditions of the fiberizing station.

[0120] As the hygrometry and the temperature may vary locally, the plant preferably comprises, at the fiberizing station 12, a plurality of relative humidity measuring devices 72a, . . . , 72n, and also a plurality of temperature measuring devices 74a, . . . , 74n, positioned respectively in various zones referred to as test zones. All of these humidity and temperature measuring devices are connected to the unit 70 for computing the optimal amount of dilution water, which, on the basis of the measurements thus obtained, computes an average of the humidity and temperature values, and deduces therefrom an average absolute humidity that can be used in the aforementioned equation as H.sub.ai.

[0121] The test zones are for example determined beforehand by producing a map of the hygrometry of the induced air using hygrometric probes distributed over the whole of the fiberizing station. These probes make it possible to detect the air flows and the differences in hygrometry, and to thus define the zones that have to be taken into account for the determination of the average ambient humidity.

[0122] The target mass flow rate of water desired in the mat D.sub.m (in kg/h) is determined by tests and depends on the required characteristics of the cured mat: it depends in particular on the density of the fibers F, on the formula of the binder composition, and on the amount of binder.

[0123] The mass flow rate of air taken in by the at least one suction duct D.sub.aa (in kg/h) is easily measurable and adjustable.

[0124] A device 76 for measuring the flow rate inside the duct 54b is here represented schematically in FIG. 2A. Advantageously, when a variation in flow rate is detected by the measuring device 76, the control device 80 accordingly adjusts the speed of the extraction fan(s) 56 to bring the flow rate back to its nominal/desired value. The intake air flow rate in said at least suction duct 54 is thus maintained at a constant value.

[0125] The measuring device 76 may communicate directly with the unit 70 for computing the optimal amount of dilution water (communication not represented in FIG. 2A).

[0126] According to another implementation example, the intake air flow rate may be measured as indicated previously, and the value thus measured may be taken into account as a variable in the determination of the optimal amount of dilution water. In this precise case, a direct communication between the measuring device 76 and the computing unit 70 is particularly advantageous.

[0127] The absolute humidity of the air H.sub.aa in the at least one suction duct 54b is, itself, measured or obtained by any suitable means (or combination of means) provided inside the duct, referenced 78 in FIG. 2A, it too in communication with the computing unit 70.

[0128] The value C.sub.e is preferably approximated by a value at least equal to the sum of the amount of water resulting from the burner 30 and of the amount of water resulting from the binder composition, which can be calculated by knowing respectively the flow rate and the composition of the air incinerated, and the flow rate of binder composition defined by adjustment and the water content of the binder composition.

[0129] More preferentially still, the value C.sub.e is approximated by a value equal to the sum of the amount of water resulting from the burner 30 and from the binder composition, but also of the amount of water resulting from the air ring 36 and/or from the air guns 38 and/or from the device 40 for applying the binding compound and/or from the possible device(s) 68 for introducing edge fragments.

[0130] The value C.sub.a is preferably approximated by a value at least equal to the sum of the amount of air resulting from the air guns 38 and from the possible device(s) 68 for introducing edge fragments.

[0131] More preferentially still, the value C.sub.a is approximated by a value equal to the sum of the amount of air resulting from the air guns 38 and from the possible device(s) 68 for introducing edge fragments, but also of the amount of air resulting from the burner 30 and from the air ring 36.

[0132] Once the optimal amount of dilution water has been computed by the computing unit 70, this amount is compared to the actual amount of dilution water at the moment considered and, if need be, the computing unit 70 controls means for adjusting the amount of dilution water so that it reaches said optimal value, here the control valve 49.

[0133] FIG. 3 is a schematic view of a plant for manufacturing a mat of mineral fibers, according to a second implementation example of the invention.

[0134] This plant differs from that described in connection with FIGS. 1 and 2 in that it comprises a circuit 90 for recirculating a portion of the intake air to the fiberizing station 12, where this air is reintroduced. As illustrated in FIG. 3, a recirculation line 92 connects each suction duct 54a, 54b, 54c to devices 94a, . . . , 94d for supplying recycled intake air which are each positioned between two fiberizing devices 20.

[0135] The recycled air flow rate represents for example X=20% to 70% of the intake air flow rate.

[0136] The determination of the optimal amount of dilution water is in this case carried out by using an equation of the type:

[Math2]

D.sub.d=D.sub.m+D.sub.aa*(H.sub.aa−H.sub.ai−X*H.sub.ar)+C.sub.a*H.sub.ai−C.sub.e  (2)

where
D.sub.d is the mass flow rate of water to be added to the binding compound (in kg/h)
D.sub.m is the target mass flow rate of water desired in the moving mat at the outlet of the receiving chamber and upstream of the drying oven (in kg/h)
D.sub.aa is the mass flow rate of air taken in by the at least one suction duct (in kg/h)
H.sub.aa is the absolute humidity of the intake air in the at least one suction duct (kg of water/kg of dry air)
H.sub.ai is the average absolute humidity of the air in the fiberizing station (kg of water/kg of dry air)
H.sub.ar is the absolute humidity of the recycled air (kg of water/kg of dry air)
X is the recycled air mass flow rate/intake air mass flow rate ratio
C.sub.a is a value representative of the amount of air resulting from the members of the fiberizing station
C.sub.e is a value representative of the amount of water resulting from the members of the fiberizing station.

[0137] It should be noted that the absolute humidity of the recycled air H.sub.ar may—or may not—be equal to the absolute humidity of the intake air H.sub.aa.

[0138] Preferably, the hygrometry of the recycled air inside the recirculation line 92 is measured by means of at least one relative humidity measuring device and of a temperature measuring device (which are not represented), each connected to the unit 70 for computing the optimal amount of dilution water.