Methods and dryers for drying panels

Abstract

The present invention relates to a method for drying panels in a drying device comprising a first stage (A) and a second stage (B), each of the two stages (A, B) having levels, each of the panels being placed on a surface formed in a different level and guided through the drying device in each level of the two stages (A, B). In the first stage (A), the panels are dried by contacting them with drying air having an elevated temperature, and in the second stage (B), the panels are dried using drying air having a lower temperature. The invention is characterized in that the support surface (F1) provided in the level of the first stage (A) for placing the panel is smaller than the support surface (F2) in the second stage (B), the panel is guided in the second stage (B) with a second speed (v2) slower than the first speed (v1) in the first stage, and the product of the first support surface (F1) and the first speed (v1) is equal to the product of the second support surface (F2) and the second speed (v2).

Claims

1. A method for drying a panel in a drying device comprising a first stage (A) and a second stage (B), wherein each of the two stages (A, B) has a hierarchical structure, each of the panels is placed on a hierarchically formed surface and is passed through the drying device in each of the hierarchical stages of the two stages (A, B), the panel is dried in contact with hot dry air in the first stage (A) and dried with dry air at a lower temperature in the second stage (B), wherein the first support surface available in the hierarchical stage of the first stage (A) for arranging the panel is smaller than the second support surface in the second stage (B), the panel is passed through the second stage (B) at a second speed slower than a first speed in the first stage, and the product of the first speed and the first support surface is equal to the product of the second speed and the second support surface.

2. The method according to claim 1, wherein the panels in the second stage (B) are guided within a greater number of layers extending above and below each other or adjacent to each other.

3. The method according to claim 1 or 2, wherein the panels are transported between the first stage (A) and the second stage (B) via a transport device, a continuous conveyor, or a discontinuous conveyor, thereby slowing down the panels until they reach the second speed.

4. The method according to claim 3, wherein the panel is raised or lowered to different levels within the transfer device, or the continuous conveyor or the discontinuous conveyor, and transferred to the level of the second stage (B).

5. The method according to claim 1 or 2, wherein the panel in the area of ​​the first step (A) is dried at least substantially by the use of a nozzle box.

6. The method according to claim 1 or 2, wherein the panel is dried by an internal heat exchanger and / or by at least one external heat exchanger in the first step (A) or the second step (B).

7. The method according to claim 1 or 2, wherein the panel is heated in the first step (A) by directly using circulating air with a burner, or by using superheated steam or thermal oil, or electrically indirectly or by using lower heating heat.

8. The method according to claim 1 or 2, wherein the panel is dried with dry air at a temperature of 130°C to 300°C in the first step (A).

9. The method according to claim 1 or 2, wherein the panel is dried with dry air at a temperature of 20°C to 90°C in the second step (B).

10. The method according to claim 1 or 2, wherein the exhaust from the first stage (A) is supplied to a heat exchanger to preheat the dry air of the second stage (B).

11. The method according to claim 1 or 2, wherein the panel is dried first in a pre-drying step upstream of the first step (A), then in the first step (A), and finally in the second step (B).

12. The method according to claim 1 or 2, wherein the panel is transported by a separate transport device for each of the steps (A, B) through a plurality of sections, each having the hierarchy.

13. A dryer for drying panels in a first stage (A) and a second stage (B), wherein the panels are dried by contact with high-temperature dry air in the first stage (A) and by using lower-temperature dry air in the second stage (B), each of the two stages (A, B) having a tier, and each of the first stage (A) and the second stage (B) being equipped with a transport device for transporting the panels arranged on a tiered surface through the dryer, the first stage (A) having at least one section, the first stage (A) having a supply device, a discharge device, a recirculation device, a recirculating air duct, a heating device for the recirculating air, means for supplying supply air, and means for discharging exhaust, and a first support surface available within the tier of the first stage (A) for arranging the panels A dryer having a supply device for dry air, a discharge device for dry air, and a heating device, wherein the second stage (B) is smaller than the second support surface in the second stage (B), and the second stage (B) takes over the panel from the first stage (A), wherein a transfer device, a continuous conveyor, or a discontinuous conveyor is positioned between the first stage (A) and the second stage (B), thereby allowing the panel to be slowed from a first transport speed in the first stage (A) to a second transport speed in the second stage (B), raised or lowered to the height of the level of the transport device in the second stage (B), or distributed to adjacent tracks of the transport device in the second stage (B), and the product of the first transport speed and the first support surface is equal to the product of the second transport speed and the second support surface.

14. The dryer according to claim 13, wherein each of the first stage (A) and the second stage (B) has at least one section and is equipped with means for flowing the circulating air transversely to the conveying direction of the panel.

15. The dryer according to claim 13 or 14, wherein the first stage (A) of the dryer has a plurality of sections that at least partially mount nozzle boxes for transverse ventilation using impinging hot air.

16. The dryer according to claim 13 or 14, wherein the second step (B) is equipped with means for flowing the circulating air in the opposite direction to and / or in the direction of conveying the panel.

17. The dryer according to claim 16, wherein the second step (B) is equipped with a guide means for guiding the circulating air in a spiral manner, or at least one exhaust air fan in combination with at least one circulating air fan.

18. The dryer according to claim 13 or 14, wherein the dryer comprises at least one heat exchanger.

19. The dryer according to claim 13 or 14, wherein the conveying device has a roller conveyor or a conveyor belt.

20. The dryer according to claim 13 or 14, wherein the panels in the preceding stages (A, B) can be transported in a plurality of trucks extending adjacently within the hierarchy.

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