阅读说明：本技术 板状物料的干燥方法及干燥设备 (Drying method and drying equipment for plate-shaped materials ) 是由 C·史特拉特曼斯 于 2020-04-05 设计创作，主要内容包括：用于干燥建筑材料板坯的方法,所述建筑材料板坯具体为包含石膏的板坯,板坯在搁板(15)中被引导通过一设备,所述设备分为干燥预备区(2)和干燥室,并且在所述设备中,板坯与干燥空气接触,其特征在于,干燥空气从干燥预备区(2)施加到区域(1)中的板坯,所述区域(1)位于预备区(2)的上游并且至少相对于板坯的输送方向在纵向侧和上侧封闭。(Method for drying building material slabs, in particular slabs containing gypsum, which are guided in shelves (15) through an apparatus which is divided into a drying preparation (2) and a drying chamber and in which the slabs are brought into contact with drying air, characterized in that drying air is applied from the drying preparation (2) to the slabs in a zone (1), which zone (1) is located upstream of the preparation (2) and is closed at least on the longitudinal side and on the upper side with respect to the conveying direction of the slabs.)

1. Method for drying building material slabs, in particular slabs containing gypsum, which are guided in shelves (15) through an apparatus which is divided into a drying preparation (2) and a drying chamber and in which the slabs are brought into contact with drying air, characterized in that drying air is applied from the drying preparation (2) to the slabs in a zone (1), which zone (1) is located upstream of the preparation (2) and is closed at least on the longitudinal side and on the upper side with respect to the conveying direction of the slabs.

2. Method according to claim 1, characterized in that the exhaust air from the drying preparation (2) flows as drying air along the mat in the closed region (1) against the conveying direction of the mat.

3. Method according to claim 1 or 2, characterized in that the drying air from the enclosed area (1) is fed into the stack (10) through a duct (8).

4. A method according to claim 3, characterized in that the drying air is extracted from the enclosed area (1) by means of a fan (9) embedded in the duct (8).

5. Method according to any of claims 1 to 4, characterized in that the supply of drying air into the enclosed area (1) is controlled or regulated by means of temperature and/or humidity sensors.

6. The method according to any one of claims 1 to 5, characterized in that a slight underpressure of 50Pa or less, in particular 25Pa or less, is generated in the closed region (1).

7. Method according to any of claims 1 to 6, characterized in that the moisture content of the air in the enclosed area (1) is controlled to a value of less than 30g, preferably 20g or less per kg of air.

8. The method according to any one of claims 1 to 7, characterized in that an air temperature of 35 ℃ to 60 ℃ is maintained in the enclosed region (1).

9. Device for drying building material slabs, in particular slabs containing gypsum, in an apparatus with drying air, which device has a shelf (15) and is divided into a drying preparation (2) and a drying chamber, characterized in that the drying preparation (2) is preceded by a closed area (1) in which drying air from the drying preparation (2) is applied to the slab.

10. The apparatus according to claim 9, characterized in that the closed region (1) has side walls and a top cover and an inlet-side cover between the shelves (15) receiving the slabs and which is open towards the drying preparation (2) for inflow of drying air.

11. The apparatus according to claim 9 or 10, characterized in that the drying air is drawn out of the enclosed area (1) by means of a fan (9) introduced into the duct (8).

12. The apparatus according to claim 11, characterized in that the duct (8) is connected to a chimney (10).

13. The apparatus according to any one of claims 9 to 12, characterised in that the apparatus comprises a control or regulating device by means of which the supply of dry air into the enclosed area (1) can be controlled or regulated by means of a temperature and/or humidity sensor.

14. The apparatus according to any of claims 9 to 13, characterized in that a bypass duct (13) is provided for evacuating excess drying air from the preparation space (2).

15. An arrangement according to claim 12 or 14, characterised in that the bypass duct (13) is connected to a stack (10).

Technical Field

The invention relates to a method and a device for drying slabs or plate-like materials, in particular slabs containing gypsum.

Background

In most cases, the drying of such plate-like materials takes place mainly by convective heat transfer in the form of hot air escape. In this process, the mat is fed through a dryer, which is usually distributed in multiple layers, by means of a conveying device such as a roller conveyor or a screen belt.

According to the prior art, dryers are usually operated in recirculation mode. The drying air is fed onto the mat several times and reheated after each contact. In this way, the air becomes more and more rich in moisture, and only a small part of the dry air is discharged as exhaust air to the environment for removing moisture and fumes.

One significant feature of various dryer designs is the introduction of air over the material to be dried. The air can be directed to the mat essentially by cross ventilation, longitudinal ventilation or so-called impinging jet ventilation.

In the case of cross ventilation, the drying air is guided laterally over the material to be dried, transversely to the conveying direction of the plate-shaped material. This results in a difference in drying speed over the entire width, since the drying air is gradually cooled as it passes through the material to be dried.

Therefore, the process is not suitable for sensitive materials (e.g. gypsum board). By means of longitudinal ventilation, the drying air travels a long distance along the longitudinal axis of the dryer, flows through the mat, dries it and thus cools it considerably.

Under impingement ventilation, the drying air is fed from the side of the dryer into ventilation ducts called nozzle boxes (nozzle boxes) and blown through outlet nozzles perpendicularly to the surface of the material to be dried. From there, the air flows to the other side of the drying system.

One of the advantages of this type of dryer is that, since its structure consists of a number of relatively short drying chambers, each of which can be individually ventilated and heated, the desired drying temperature and environment can be freely selected over the length of the dryer. Thus, the drying conditions can be adapted to the requirements of the material to be dried. The dryer also provides excellent controllability, for example, for changing products. Such a dryer can be much shorter than a similar dryer with longitudinal air flow due to good heat transfer during impinging flow. Such a system is described in DE1946696a1 under the heading of a process and apparatus for accelerated drying of gypsum board. However, no information is provided about a particularly advantageous implementation of energy saving.

In principle, the energy efficiency of all these forms of ventilation can be increased by heating the fresh air by means of a heat exchanger. The fresh air heated in this way is then used as combustion air or for pre-drying.

DE2613512a1 discloses a secondary drying method and a drying system. According to DE2613512a1, the aim is to modify or supplement the known secondary drying process so that in particular gypsum boards or items with similar properties can be dried with particular energy savings using this process. In one feature, a heat exchanger is used to heat the circulating air in the downstream impingement jet through-air-drying zone.

DE102009059822B4 describes a method for drying a mat, in which the mat is guided in layers through a device which is divided into a plurality of drying chambers, the mat is contacted with the drying air in the drying device by means of impinging jet ventilation, and the impinging jet ventilation is provided by means of laterally ventilated nozzle boxes. Here, the drying device is the main drying stage or the final drying stage in the drying apparatus.

This process is based on the fact that the dry exhaust air should be as cold as possible before entering the heat exchanger. This further improves energy efficiency. In this connection, the use of preheated fresh air for the pre-drying of slabs in upstream cross-ventilated preparation zones (pre-zones) is also mentioned.

Disclosure of Invention

The object of the present invention is to create a drying process which is more efficient than the conventional process. For this purpose, the exhaust air of the preparation zone will be used for preheating the mat in the inlet area of the dryer. The energy transferred in this way will no longer need to be supplied by the burner in the subsequent process, resulting in a thermal advantage.

According to the invention, this object is solved as disclosed in claim 1.

In contrast to other conventional processes, according to the invention gypsum-containing board-like materials, such as gypsum board and gypsum fibre board, have been exposed to warm air from the drying preparation zone of the dryer during the setting stage (hydration). The curing phase, which typically lasts 8 to 12 minutes, includes the area in front of the dryer where the mat has been separated into layers.

The present invention is based on the following surprising findings: contrary to expectations, the mat, which has not yet been fully cured, i.e. is still in the final stage of the curing process, can be exposed to moderately warm drying air without hindering in any way the complete hydration.

Advantageous further embodiments are apparent from the dependent claims and the description, in particular with reference to the drawings.

Advantageously, the method is characterized in that the exhaust air from the drying preparation space flows as drying air along the mat in the closed area counter to the conveying direction of the mat and is cooled in the process.

It is further provided that the cooling air is drawn off and released into the environment.

In order to control the air flow, i.e. to supply dry air to the enclosed area, a temperature and/or humidity sensor is preferably provided.

According to the invention, a slight underpressure of 50Pa or less, in particular 20Pa or less, is generated in the enclosed area by the fan. Preferably, the moisture content of the air in the enclosed area is controlled to a value of less than 30g, preferably 20g or less per kg of air. Preferably, an air temperature of 35 ℃ to 60 ℃ is maintained in the enclosed area. The environment created in this way has the effect that dew point undershoots (an undershoot of the dew point) can be effectively avoided, in particular where the slab enters the enclosed area. For example, such dew point undershoots can lead to water droplets dripping in punctiform fashion onto the surface of the slab and causing undesirable discoloration there.

The apparatus according to the invention also provides a multi-deck dryer for drying a mat containing gypsum. The apparatus is characterized in that the drying preparation is preceded by an enclosed area in which drying air from the drying preparation is applied to the mat.

Preferably, the enclosed region includes side walls and a top cover and an inlet-side cover between the shelves that receive the slabs; it opens towards the drying preparation area for the inflow of drying air. The walls and covers may also be provided with doors or windows.

Furthermore, it is advantageous to use a fan in the area of the duct, by means of which the drying air is drawn from the enclosed area after it has absorbed moisture from the mat in the enclosed area and has heated it somewhat.

It is also advantageous to use a duct to discharge the drying air with saturated moisture through a duct connected to a chimney.

If the apparatus further comprises a control or regulating device by means of which the supply of drying air to the closed area can be controlled by means of a temperature and/or humidity sensor, the operating mode of the closed area upstream of the preparation area is optimized.

Furthermore, a bypass duct is preferably provided to remove excess drying air from the preparation area that is not needed in the enclosed area. In this way, when the bypass duct is connected to the stack, excess drying air can be discharged together with air from the enclosed area.

Drawings

The invention will be explained in more detail below with reference to the drawings. The method comprises the following specific steps:

fig.1 is an isometric view of a closed area in front of a preparation area of a drying apparatus for drying board-like items, with the segmented board forming the outer wall omitted,

figure 2 is a vertical cross-sectional view of the longitudinal enclosed area along section line II-II in figure 1,

FIG.3 is a vertical cross-sectional view of the enclosed area along section line III-III in FIG.1, an

Fig.4 is a horizontal cross-sectional view of the enclosed area along section line IV-IV in fig. 1.

Detailed Description

An enclosed area 1 (fig. 1-4) extends between a loading area 20 (or feed device) and a preparation area 2 of the drying apparatus. In this region, the hardening or curing process of the board blank, in particular of the plasterboard, is completed. The preparation space 2 is connected without any transition to the area 1 and extends to the front wall 3 of the preparation space 2, so that the drying air flows from the preparation space 2 into the area 1 and heats the mat to a temperature of up to 60 ℃. At the same time, a negative pressure and a humidity of less than 30 grams of water per kilogram of air are maintained in zone 1 so that the drying air absorbs moisture from the mat and supports the curing process in the mat.

In the top zone, the drying air is supplied by two protrusions 4, 5, each located laterally and on both sides of the zone 1. The moisture-enriched air flows from the protrusions 4, 5, through the inlet ducts 6, 7 to the central exhaust duct 8 and into the chimney 10, the central exhaust duct 8 extending above the zone 1 and comprising a fan 9, the chimney 10 in turn being equipped with a filter system 11.

On the front wall 3 of the preparation space 2, on one or both sides of the front wall 3, there are provided exhaust openings 12, from which exhaust openings 12a bypass duct 13 leads to a flange 14, which bypass duct 13 is connected to the exhaust duct 8 via the flange 14, so that the drying air is discharged from the preparation space 2 if necessary.

Internally, zone 1 has a shelf 15 with rollers 16 (fig. 3). The wall is formed by a plurality of segmented panels 17 (fig. 4) which are preferably hinged to allow easy access to the interior of the area 1 for inspection work and control.

In the direction of the feed zone for slab feeding, sheet metal strips (not shown) are connected to the feed openings between the shelves 15, which are open only when the slab is conveyed on the shelves 15 to such an extent that it can be introduced, but the rest of the zone 1 remains closed. Sealing elements are also arranged on two sides of the plate blank at the feeding opening.