CURING OVEN AND METHOD OF CONTROLLING CURING OVEN

Abstract

A curing oven for curing a mineral wool web includes an air permeable conveyor for advancing the mineral wool web through a substantially closed cabinet from a mineral wool web inlet provided at one end of the cabinet to a mineral wool web outlet provided at another end of the cabinet. The curing oven also includes a heated air inlet arranged for directing a flow of heated air through the conveyor. The curing oven includes at least one wool deformation detector.

Claims

1. A curing oven for curing a mineral wool web, comprising: an air permeable conveyor for advancing the mineral wool web through a substantially closed cabinet from a mineral wool web inlet provided at one end of the cabinet to a mineral wool web outlet provided at another end of the cabinet; a heated air inlet arranged for directing a flow of heated air through the conveyor; wherein the curing oven comprises at least one wool deformation detector configured for detecting wool deformation inside the curing oven.

2. The curing oven according to claim 1, wherein the wool deformation detector comprises a transmitter arranged at a first edge region at one side of the conveyor and a receiver arranged at a second edge region of at an opposite side of the conveyor to transmit an electromagnetic signal transversely through the web.

3. The curing oven according to claim 2, wherein the electromagnetic signal is X-ray.

4. The curing oven according to claim 2, wherein the receiver has a vertical extension of 10-20 mm.

5. The curing oven according to claim 1, wherein the curing oven comprises a plurality of zones, and a wool deformation detector is arranged in at least one of the zones.

6. The curing oven control system for a curing oven according to claim 1, wherein the control system is configured to regulate pressure of the flow of heated air based on input from the wool deformation detector.

7. A method for curing mineral wool in a curing oven comprising the steps of: advancing a mineral wool web through a substantially closed cabinet from a mineral wool web inlet provided at one end of the cabinet to a mineral wool web outlet provided at another end of the cabinet, directing a flow of heated air through the conveyor and into the mineral wool web, detecting potential wool web deformation in the curing oven.

8. The method according to claim 7, wherein the step of detecting potential wool web deformation comprises: emitting an electromagnetic signal transversely through the web from a first edge region, receiving the electromagnetic signal at a second edge region opposite the first edge region, analysing the received electromagnetic signal to provide a control value, generating a first signal if the control value indicates deformation of the wool, generating a second signal if the control value indicates no deformation of the wool, the method further comprising a step of regulating the pressure of heated air at the heated air inlet based on the first or second signal.

9. A method for curing mineral wool, comprising: curing mineral wool with a curing oven according to claim 1; wherein the mineral wool web has a density in the range of 15-50 kg/m.sup.3.

10. The method according to claim 9, wherein the mineral wool web is a mineral wool web made of fibres having a median diameter below 3 μm.

11. The curing oven according to claim 5, wherein the wool deformation detector is arranged in the first half of the curing oven seen in direction of transport of the conveyor.

Description

DETAILED DESCRIPTION OF THE DRAWINGS

[0026] In the following the invention will be described in more detail with reference to examples and the figures, of which:

[0027] FIG. 1 is a longitudinal section of part of a prior art mineral wool production line;

[0028] FIG. 2 is a cross sectional sketch of a curing oven;

[0029] FIG. 3 is another cross sectional sketch of the curing oven;

[0030] FIG. 4 is another cross sectional sketch of the curing oven; and

[0031] FIG. 5 is a sketch of method steps.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Production of mineral wool is illustrated in the longitudinal section of FIG. 1. FIG. 1 illustrates production of fibres 9, application of binder 10, collection of the fibres as a mineral wool web 2 on a collection conveyor 11. The mineral wool web 2 is transported to a curing oven 1 having a cabinet 4 (shown in longitudinal section), into a mineral wool web inlet 5 of the cabinet 4, through the curing oven 1 on an air permeable conveyor 3 to a mineral wool web outlet 6. Heated air enters into the curing oven 1 through a heated air inlet 7 and is forced through the conveyor 3 and into the wool web 2 for curing the binder 10 of the mineral wool web 2. Exhaust from the curing oven is through an exit 8, and the air may be recycled and reheated or undergo waste gas treatment. In the example shown the curing oven comprises two zones 16, 17, but there may be only one or a plurality, such as seven.

[0033] Man-made vitreous fibres may be produced in different ways, such as in a spinning cup (typically used for producing glass wool fibres) or on a cascade spinner (typically used for producing stone wool fibres).

[0034] In FIG. 2 is seen a curing oven 1 in cross section. The curing oven 1 comprises a set of conveyors 3 arranged in the cabinet 4 of the curing oven 1. The conveyors 3 are permeable to air, e.g. using perforated slats or panels. The mineral wool web 2 is arranged between conveyors 3 and transported thereby through the curing oven 1. Heated air at elevated pressure is forced into the mineral wool web 2 to heat the web and cure the binder. The temperature of the air may be adjusted to ensure drying of the web and curing of the binder. Suitable temperature depends inter alia on the specific binder and may be in the range of 180-260° C., although higher and lower temperatures are possible and may be advantageous in some cases.

[0035] If the pressure of the heated air in the curing oven is too high there is a risk of unwanted deformation of the mineral wool web as the wool web may lift from the conveyor and compress in areas as illustrated by the void 14 between the web and the lower conveyor seen in FIG. 3. In this event the mineral wool web is deformed prior to curing and the mineral wool web will be cured in the deformed state meaning that the product is sub standard and must be discarded.

[0036] An emitter 12 is provided at one edge region of the web to emit an electromagnetic signal crosswise through the web to a receiver 13 arranged at an opposite edge region of the web as illustrated in FIG. 4 and making up a wool deformation detector. The signal received by the receiver 13 will depend on the mineral wool between emitter 12 and the receiver 13. In case of unwanted compression leading to the wool web not being in contact with the conveyor there suddenly is less mineral wool present in the line of the emitted signal from the emitter 12 to the receiver, and hence the received signal will be different from when the signal has to pass mineral wool all the way from emitter to receiver. The signal may be analysed in a processor 15 providing a control value and a first signal indicating web deformation or a second signal indicating no web deformation. Based on the first or second signal the heated air pressure may be regulated down or up, respectively, to maximise the curing oven performance.

[0037] The emitter 12 and receiver 13 should be arranged close to the conveyor 3 into which the heated air is forced as illustrated in FIG. 4.

[0038] Method steps in operating a curing oven comprises providing a sensor system, feeding the signal therefrom into a signal analyser producing a value and generating an output using an output generator based on this value as schematically illustrated in FIG. 5. The sensor system may be an X-ray emitter and an X-ray receiver. The output from the output generator may be used for a control system regulating pressure of heated air.

[0039] The estimated potential of the invention is increasing curing oven capacity by up to 20% if the curing oven is controlled to operate closer to the limit of deforming the mineral wool web.