Method and device for drying boards

Abstract

In a method for drying boards, which are guided in decks through a drying device, wherein the boards (8) in the drying device are brought into contact with drying air by means of an impinging jet ventilation and wherein the impinging jet ventilation is ensured by means of transversely ventilated nozzle boxes (7), the drying air is supplied by means of at least two fans (4a, 4b) arranged next to one another in an airflow of the drying air produced by a burner (1), which guides the drying air to the fans (4a, 4b).

Claims

1. A method for drying boards, wherein the method comprises guiding the boards through a drying device, bringing the boards in the drying device into contact with drying air by an impinging jet ventilation, the impinging jet ventilation being ensured by transversely ventilated nozzle boxes, and the drying air being heated by a single burner in a ceiling unit arranged above the nozzle boxes and being supplied to at least two fans arranged next to one another in an air flow of the drying air and thereafter being passed to a pressure chamber which is located at a side of the nozzle boxes, the drying device comprising the ceiling unit in which the single burner heats the drying air, and the ceiling unit comprising the at least two fans arranged next to one another and in a way such that they can be supplied with the heated drying air from the single burner, and a ratio of an intake height of the at least two fans, in relation to an outer impeller diameter, being at least 0.5.

2. The method of claim 1, wherein each of the at least two fans comprises a direct drive.

3. The method of claim 1, wherein each of the at least two fans is enclosed by a volute housing.

4. The method of claim 1, wherein each of the at least two fans comprises a four-pole motor or an asynchronous motor.

5. The method of claim 1, wherein the ratio of the intake height of the at least two fans, in relation to the outer impeller diameter, is greater than 0.8.

6. The method of claim 1, wherein a ratio of the outer impeller diameter of one of the at least two fans to a distance between a lateral impeller outlet for drying air exiting the at least two fans and a wall of the ceiling unit above the pressure chamber and adjacent to the nozzle boxes is greater than 3.5.

7. The method of claim 1, wherein the at least two fans can be operated with opposite rotations.

8. The method of claim 1, wherein the nozzle boxes are tapered in a direction of flow of air.

9. The method of claim 1, wherein the at least two fans are separated by a partition.

10. The method of claim 1, wherein the at least two fans are arranged in the ceiling unit in a way such that they are capable of sucking heated air from the single burner into the at least two fans from below and passing it through lateral impeller outlets into the pressure chamber.

11. A method for drying boards, wherein the method comprises guiding the boards through a drying device, bringing the boards in the drying device into contact with drying air by an impinging jet ventilation, the impinging jet ventilation being ensured by transversely ventilated nozzle boxes, and the drying air being heated by a single burner in a ceiling unit arranged above the nozzle boxes and being supplied to at least two fans arranged next to one another in an air flow of the drying air and thereafter being passed to a pressure chamber which is located at a side of the nozzle boxes, the drying device comprising the ceiling unit in which the single burner heats the drying air, and the ceiling unit comprising the at least two fans arranged next to one another and in a way such that they can be supplied with the heated drying air from the single burner, and a ratio of an outer impeller diameter of one of the at least two fans to a distance between a lateral impeller outlet for drying air exiting the at least two fans and a wall of the ceiling unit above the pressure chamber and adjacent to the nozzle boxes being greater than 3.5.

12. The method of claim 11, wherein each of the at least two fans comprises a direct drive.

13. The method of claim 11, wherein each of the at least two fans is enclosed by a volute housing.

14. The method of claim 11, wherein each of the at least two fans comprises a four-pole motor or an asynchronous motor.

15. The method of claim 11, wherein the at least two fans can be operated with opposite rotations.

16. The method of claim 11, wherein the nozzle boxes are tapered in a direction of flow of air.

17. The method of claim 11, wherein the at least two fans are separated by a partition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the device in accordance with the invention is described further with the aid of an illustrative embodiment. The figures show:

(2) FIG. 1 a longitudinal section of a drying device and

(3) FIG. 2 a level sectional view along a section line A-A shown in FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENT OF THE INVENTION

(4) Drying air flows in a drying device (FIGS. 1, 2), the direction of flow of which is indicated by arrows. Pre-heated fresh air is fed to a burner 1 as combustion air. The further conveyance of the air heated by the burner 1 into a pressure chamber 5 occurs via recirculation fans 4a, 4b (FIG. 2). The pressure chamber 5 serves to distribute the air evenly into the individual decks of a drying chamber 6. In the process, the air is first pressed into nozzle boxes 7 (merely one of which is depicted illustratively in FIG. 1), from which it is blown perpendicularly onto gypsum boards 8 or other boards to be dried via hole nozzles 70 (only a few hole nozzles 70 are depicted illustratively in FIG. 1), which for the sake of clarity are only illustrated in the upper drying level of the drying chamber 6 and which are arranged on the top or bottom side of the nozzle boxes. The boards 8 lie on supports (not illustrated here), such as e.g. supporting rollers, and are conveyed by means of a transport installation (also not described here further) in a direction perpendicular to the viewing plane.

(5) In order to ensure an even distribution of the air over the width, the nozzle boxes 7 are configured to be tapered in the direction of flow of the air. The air escaping from the nozzle boxes 7 via the hole nozzles 70 then flows above and below the boards 8 into a vacuum chamber 9. A part of the air, which in sum essentially corresponds to the combustion gases, the fresh air and the water vapour generated by the drying action, escapes via an exhaust-air outlet. The air flow circuit is completed at the burner 1. The section above the pressure chamber 5, the drying chamber 6 and the vacuum chamber is the ceiling unit 11, also referred to as the overhead unit.

(6) The fans 4a, 4b arranged in the ceiling unit 11 are arranged next to one another at a distance from the burner 1 and separated from one another by a partition 40. Both fans 4a, 4b are respectively enclosed by a volute housing 41. Both fans 4a, 4b are preferably arranged eccentrically in the area between the partition 40 and an outer wall 42 or 43 of the ceiling unit 11, wherein they are mounted closer to the outer walls 42, 43 than to the partition 40. It has been shown that, this way, for reasons relating to fluid dynamics, a more even supply of the drying air into the pressure chamber 5 is achieved.

(7) The ratio of the outer impeller diameter of each fan 4a, 4b to a distance d between a lateral impeller outlet of the air exiting the fans 4a and 4b and a wall 50 of the ceiling unit 11 above the pressure chamber 5 is greater than 3.5.

(8) For guiding the drying air exiting the burner to the underside of the fans 4a, 4b, an air guiding profile 12 and a wall 13 are provided.