阅读说明：本技术 一种联合干燥方法及其干燥装置 (Combined drying method and drying device thereof ) 是由 窦青青 陈龙 倪豪 倪月萍 严志松 陈震乾 王文斌 倪月忠 周庆东 周永东 于 2021-08-23 设计创作，主要内容包括：本申请实施例公开了一种联合干燥方法及其干燥装置,材料置于干燥介质环境,包括调控干燥介质温度的第一调温单元、调控所述干燥介质湿度的蒸汽调湿单元、令所述干燥介质形成流速的流体动力单元,还包括调控所述干燥介质温度的第二调温单元,所述第二调温单元包括多个第二调温体,所述第二调温体至少位于材料的一个表面的侧部,并与其所对应的表面之间具有间距。其能够提高干燥效率、避免干燥缺陷的形成；不依赖于含水率监控、水蒸气压力监控结果,避免了监控误差带来的问题；可提高干燥后材料的表面平整度,有助于干燥表裂的修复,避免暗裂的发生。(The embodiment of the application discloses a combined drying method and a drying device thereof, wherein a material is placed in a drying medium environment and comprises a first temperature regulating unit for regulating and controlling the temperature of the drying medium, a steam humidity regulating unit for regulating and controlling the humidity of the drying medium, and a fluid power unit for enabling the drying medium to form a flow velocity, and further comprises a second temperature regulating unit for regulating and controlling the temperature of the drying medium, wherein the second temperature regulating unit comprises a plurality of second temperature regulating bodies, and the second temperature regulating bodies are at least positioned on the side part of one surface of the material and have a distance with the corresponding surface. The drying efficiency can be improved, and the formation of drying defects can be avoided; the water content monitoring and the steam pressure monitoring result are not depended on, so that the problems caused by monitoring errors are avoided; the surface smoothness of the dried material can be improved, the repair of the dried surface cracks is facilitated, and the occurrence of dark cracks is avoided.)

1. The combined drying method is characterized by further comprising a second temperature regulating unit for regulating the temperature of the drying medium, wherein the second temperature regulating unit comprises a plurality of second temperature regulating bodies, and the second temperature regulating bodies are at least positioned on the side part of one surface of the material and have intervals with the corresponding surface.

2. The integrated drying process of claim 1, wherein the second temperature conditioner is located on the side of both surfaces of the material.

3. The integrated drying method according to claim 1, wherein the second temperature-adjusting body is spaced from the surface of the material corresponding thereto by 0.5cm to 3.0 cm.

4. The integrated drying method according to claim 3, wherein the second temperature control body is a flat plate type heat supply body.

5. The integrated drying method according to claim 1, 2, 3 or 4, wherein the first temperature regulating unit and the second temperature regulating unit are heated by the same heat source; during the drying process, the maximum temperature of the drying medium is 52-55 ℃.

6. The combined drying method according to claim 5, wherein in the drying process, the drying medium is heated to 40-45 ℃ at a heating rate of 1.5-2.0 ℃/h, and is kept warm for 8-10 h; heating to the highest temperature of the drying medium at the heating rate of 2.0-2.5 ℃/h, and keeping the temperature for 48-60 h, wherein the humidity of the drying medium is controlled to be lower than 86-92% RH; the cooling speed of the drying medium is 1.0 ℃/h to 3.0 ℃/h; the fluid power unit enables the drying medium to form a flow speed of 3-5 m/s.

7. The combined drying method according to claim 1 or 2 or 3 or 4, wherein the first temperature regulating unit and the second temperature regulating unit are respectively heated by two heat sources; during the drying process, the maximum temperature of the drying medium is 50-53 ℃.

8. Combined drying method according to claim 7, characterized in that it comprises the following drying phases:

s1, in a preheating stage, enabling the drying medium to be heated to 40-45 ℃ at a heating speed of 1.5-2.0 ℃/h by the first temperature regulating unit and the second temperature regulating unit;

s2, in a first heat preservation stage, when the temperature of the drying medium reaches 40-45 ℃, preserving heat for 8-10 h;

s3, in a temperature rising stage, the first temperature regulating unit and the second temperature regulating unit enable the drying medium to rise to the highest temperature of the drying medium at a temperature rising speed of 2-2.5 ℃/h;

s4, in a second heat preservation stage, after the temperature of the drying medium reaches the highest temperature, keeping the constant temperature until the relative humidity of the drying medium reaches 86-92% RH, continuing to preserve heat for 48-60 h after the relative humidity of the drying medium reaches the highest humidity, and meanwhile, keeping the relative humidity of the drying medium at the highest humidity in a dehumidification mode;

s5, in a cooling stage, after the relative humidity of the drying medium reaches the highest humidity, the first temperature regulating unit and the second temperature regulating unit enable the drying medium to be cooled to be below 40 ℃ at a cooling speed of 1.0-3.0 ℃/h, and the relative humidity of the drying medium is reduced by moisture removal;

in the S4. second heat preservation stage, when the temperature of the drying medium in the circulation branch circuit is higher than that of the drying medium in the circulation main circuit by 3.0 ℃, the second temperature adjusting body controls the drying medium in the circulation branch circuit to reduce the temperature;

in the s5, in the temperature reduction stage, when the difference between the temperature of the drying medium in the circulation branch and the temperature of the drying medium in the circulation main path is less than 3 ℃, the second temperature regulator controls the temperature of the drying medium in the circulation branch to be increased, and the temperature of the drying medium in the circulation branch is higher than the temperature of the drying medium in the circulation main path by 5.0 to 6.0 ℃.

9. A drying device for executing the combined drying method according to claim 1, comprising a drying kiln body, wherein a first temperature adjusting unit, a steam humidity adjusting unit, a fluid power unit and a control system are arranged in the drying kiln body, and the drying kiln body is provided with a second temperature adjusting unit, the second temperature adjusting unit comprises a frame body, a plurality of second temperature adjusting bodies fixedly arranged through the frame body and a pipeline communicated with the second temperature adjusting bodies, the second temperature adjusting bodies are arranged in a stacked manner, a plurality of hollow partition strips are fixedly arranged on at least one surface of each second temperature adjusting body, and the first temperature adjusting unit and the second temperature adjusting unit are heated by the same heat source.

10. A drying device for executing the combined drying method according to claim 1, comprising a drying kiln body, wherein a first temperature adjusting unit, a steam humidity adjusting unit, a fluid power unit and a control system are arranged in the drying kiln body, and the drying kiln body is provided with a second temperature adjusting unit, the second temperature adjusting unit comprises a frame body, a plurality of second temperature adjusting bodies fixedly arranged through the frame body and a pipeline communicated with the second temperature adjusting bodies, the second temperature adjusting bodies are arranged in a stacked manner, and a plurality of hollow partition strips are fixedly arranged on at least one surface of each second temperature adjusting body, the first temperature adjusting unit is heated by a first heat source, and the second temperature adjusting unit is heated by a second heat source.

Technical Field

The invention relates to the technical field of drying processes, in particular to a combined drying method and a drying device capable of executing the combined drying method.

Background

In order to relieve the pressure of raw materials caused by insufficient accumulation of hard broad-leaved wood, China begins to utilize a large amount of artificial forest wood. However, the wood quality of the artificial forest wood is lower than that of the natural forest wood, and the drying difficulty is greatly different from that of the natural forest wood.

In the prior art, kiln drying methods are commonly used for drying artificial forest wood, and a softer drying standard compared with natural forest is adopted, however, the drying methods have the problems of long drying period and high drying energy consumption, and the relatively softer drying standard still cannot completely or relieve drying defects such as shrinkage and the like.

Another drying method is respiratory hot-press drying, for example, chinese patent CN201910476778.2 discloses a "respiratory wood hot-press drying process formulation method based on the change of the internal vapor pressure of wood", which discloses a staged hot-press opening and closing process determined by using the water content and the internal vapor pressure of wood as indexes, i.e., a respiratory hot-press drying process. However, such a drying method has problems that drying defects (such as internal crack, dark crack, shrinkage, etc.) are relatively large, the drying process is difficult to monitor, the drying defects are mainly caused by the limitations of hot press drying, the drying process is difficult to monitor, the differences are large among the plates, and the differences exist among various parts in the plates, so that the sample representativeness is poor.

Therefore, the prior art lacks a drying process for artificial forest wood with relatively high drying efficiency and relatively good drying quality.

Disclosure of Invention

A first technical object of the present invention is to overcome the above technical problems, and to provide a combined drying method, wherein a second temperature adjusting unit is disposed on a circulation branch of a drying medium, so that the heating rates and real-time temperatures of the drying medium in a main circulation path and the circulation branch are consistent, thereby improving the drying efficiency and avoiding the formation of drying defects; meanwhile, the kiln drying device has the advantages of kiln drying, can adopt a drying standard of which the time standard is assisted by the water content standard, does not depend on the water content monitoring and water vapor pressure monitoring results, and avoids the problems caused by monitoring errors; on the other hand, the second temperature regulating body is separated from the surface of the material, so that steam ironing treatment similar to steam ironing is performed on the material, the surface flatness of the dried material can be improved, the repair of dry surface cracks is facilitated, and the occurrence of dark cracks is avoided. A second technical object of the present invention is to provide a drying apparatus that can perform the combined drying method.

In order to achieve the above object, a first embodiment of the present invention provides a combined drying method, in which a material is placed in a drying medium environment, and the combined drying method includes a first temperature adjustment unit for adjusting a temperature of the drying medium, a steam humidity adjustment unit for adjusting a humidity of the drying medium, a hydrodynamic unit for making the drying medium flow, and a second temperature adjustment unit for adjusting the temperature of the drying medium, where the second temperature adjustment unit includes a plurality of second temperature adjustment bodies, and the second temperature adjustment bodies are located at least on a side portion of one surface of the material and have a distance from the corresponding surface.

In the kiln type drying method in the prior art, when the drying medium in the center of a material frame formed by stacking single material sheets reaches 60-65 ℃, the temperature of the drying medium in a main circulation path (the main drying medium circulation path refers to an airflow channel between the material frame and the wall of a kiln body, and a branch drying medium circulation path refers to an airflow channel formed between materials in the material frame) may reach 68-72 ℃, and the drying medium is heated too high to increase drying energy consumption. The temperature difference between the high temperature and the low temperature outside the temperature rise process makes the water in the center of the thickness of the material difficult to discharge, and influences the drying speed of the process. This is because the moisture of the material outside the material rack is discharged faster than the material in the center of the material rack, and the relative humidity of the drying medium around the material outside the material rack is higher than the drying medium around the material in the center of the material rack, which makes it difficult to discharge the moisture of the material in the center of the material rack. In the prior art, in order to avoid that the reduction of the water content of the material frame center material is smaller than that of the material frame outside material in the temperature rise stage and avoid the formation of the early drying defect, a kiln closing mode is often adopted, namely, in a period of time, the temperature rise is avoided, steam is not sprayed, an exhaust window is closed, the internal and external temperatures of the material frame in the kiln are consistent, and the next step of the drying reference is executed after the water content of the material frame center material is close to that of the material outside.

In the technical scheme of the application, by means of the method, firstly, the second temperature regulating unit is arranged on the circulation branch of the drying medium, so that the heating speeds and the real-time temperatures of the drying medium of the circulation main path and the circulation branch in the heating process can be kept consistent to a certain extent, and in the practice of the technical scheme, the real-time temperature difference between the two can be smaller than 3.0 ℃. In one aspect, therefore, the temperature of the drying medium in the main flow path and the temperature of the drying medium in the branch flow path are maintained to be equal to each other during the temperature rise of the drying medium, so that the moisture in the material in the center of the rack can be discharged at a rate close to the rate of discharging the moisture in the material outside the rack during the temperature rise. The drying speed in the temperature rise stage is accelerated, so that the drying efficiency can be improved to a certain extent. In practice, the difference between the detected real-time moisture content reduction values can be less than 4%. In the second aspect, because the heating rates and the real-time temperatures of the drying media of the main circulation path and the branch circulation path are basically consistent in the heating process, the drying defects caused by temperature fluctuation, such as dark cracks, can be avoided to a certain extent without the condition of temperature fluctuation, and the formation of the drying defects can be effectively avoided. In the third aspect, the drying medium in the main circulation path is not heated too high, and the temperature fluctuation of the drying medium in the kiln is not required to be stabilized additionally (the temperature of the drying medium in the kiln is uniform and does not depend on the circulation flow of the drying medium), and the drying period can be shortened by accelerating the drying speed, so that the drying energy consumption can be reduced to a certain extent.

Secondly, the combined drying method has the advantages of kiln drying, can adopt a drying standard of which the time standard is assisted by the water content standard, does not depend on the results of water content monitoring and water vapor pressure monitoring, and avoids the problems caused by monitoring errors.

Finally, the second temperature regulating body is spaced from the surface of the material, so that steam ironing treatment similar to steam ironing can be performed on the material by means of a drying medium with relatively high relative humidity in the later drying period, and the surface flatness of the dried material can be improved; the moisture absorption treatment of material surface (in dry later stage, in order to reduce material surface and sandwich layer moisture content deviation, when promoting material sandwich layer moisture migration, need make material surface moisture absorption) in the dry later stage is helped, makes the moisture content even in the material thickness direction to help the restoration of dry table fracture, avoid the emergence of dark fracture.

As a preferred embodiment, the second temperature-regulating body is located on the side of both surfaces of the material.

In a preferred embodiment, the second temperature control member is spaced from the surface of the corresponding material by a distance of 0.5cm to 3.0 cm.

In a preferred embodiment, the second temperature control body is a flat plate type heat supply body.

In a preferred embodiment, the first temperature regulating unit and the second temperature regulating unit are heated by the same heat source; during the drying process, the maximum temperature of the drying medium is 52-55 ℃.

As a preferred embodiment, in the drying process, the drying medium is heated to 40-45 ℃ at the heating rate of 1.5-2.0 ℃/h and is kept at the temperature for 8-10 h; heating to the highest temperature of the drying medium at the heating rate of 2.0-2.5 ℃/h, and keeping the temperature for 48-60 h, wherein the humidity of the drying medium is controlled to be lower than 86-92% RH; the cooling speed of the drying medium is 1.0 ℃/h to 3.0 ℃/h; the fluid power unit enables the drying medium to form a flow speed of 3-5 m/s.

In a preferred embodiment, the first temperature regulating unit and the second temperature regulating unit are respectively heated by two heat sources; during the drying process, the maximum temperature of the drying medium is 50-53 ℃.

In the prior art, with the progress of drying, the moisture of the material is volatilized to rapidly raise the temperature of a drying medium in the center of a material rack, the formed temperature fluctuation greatly influences the drying quality of the material, and the drying defects in the early drying stage such as dark cracks are formed. Meanwhile, in order to reduce the temperature of the drying medium in the center of the material rack to 50 ℃ -55 ℃ (the temperature which the drying medium is actually expected to reach is the standard), a skylight is opened for multiple times and a long time to perform exhaust, temperature reduction and humidity reduction (the temperature control in the drying kiln is a repeated regulation and control process), the drying medium in the main circulation path caused by the exhaust process is reduced before the drying medium in the branch circulation path, the first temperature control unit is triggered to heat the drying medium in the kiln, and the temperature fluctuation of the drying medium is caused again. The temperature fluctuation of the drying medium not only affects the drying quality and causes drying defects such as surface cracks, dark cracks and the like to be formed, but also consumes a large amount of drying energy to maintain the temperature of the drying medium.

According to the technical scheme, the first temperature regulating unit and the second temperature regulating unit are heated by different heat sources by means of the method, so that the first temperature regulating unit and the second temperature regulating unit can work respectively. Along with the drying, when the material moisture volatilizes and makes the drying medium temperature in material frame center rise fast, can make the reverse work of second thermoregulation unit to the drying medium cooling in material frame center avoids drying medium temperature to fluctuate, thereby improves drying quality, reduces the drying energy consumption.

As a preferred embodiment, the combined drying method comprises the following drying stages:

s1, in a preheating stage, enabling the drying medium to be heated to 40-45 ℃ at a heating speed of 1.5-2 ℃/h by the first temperature regulating unit and the second temperature regulating unit;

s2, in a first heat preservation stage, when the temperature of the drying medium reaches 40-45 ℃, preserving heat for 8-10 h;

s3, in a temperature rising stage, the first temperature regulating unit and the second temperature regulating unit enable the drying medium to rise to the highest temperature of the drying medium at a temperature rising speed of 2-2.5 ℃/h;

s4, in a second heat preservation stage, after the temperature of the drying medium reaches the highest temperature, keeping the constant temperature until the relative humidity of the drying medium reaches 86-92% RH, continuing to preserve heat for 48-60 h after the relative humidity of the drying medium reaches the highest humidity, and meanwhile, keeping the relative humidity of the drying medium at the highest humidity in a dehumidification mode;

s5, in a cooling stage, after the relative humidity of the drying medium reaches the highest humidity, the first temperature regulating unit and the second temperature regulating unit enable the drying medium to be cooled to be below 40 ℃ at a cooling speed of 1-3 ℃/h, and the relative humidity of the drying medium is reduced by moisture removal;

in the S4. second heat preservation stage, when the temperature of the drying medium in the circulation branch circuit is higher than that of the drying medium in the circulation main circuit by 3 ℃, the second temperature adjusting body controls the drying medium in the circulation branch circuit to be cooled;

in the s5, in the temperature reduction stage, when the difference between the temperature of the drying medium in the circulation branch and the temperature of the drying medium in the circulation main path is less than 3 ℃, the second temperature regulator controls the temperature of the drying medium in the circulation branch to be increased, and the temperature of the drying medium in the circulation branch is higher than the temperature of the drying medium in the circulation main path by 5 ℃ to 6 ℃.

By means of the method, in the S4. second heat preservation stage, when the temperature of the drying medium in the circulation branch circuit is 3 ℃ higher than that of the drying medium in the circulation main circuit, the second temperature regulating body controls the drying medium in the circulation branch circuit to cool, at the moment, the real-time temperature of the material is higher than that of the drying medium in the drying medium circulation branch circuit, and therefore moisture absorption treatment of the surface of the material can be completed at the later stage of drying, the moisture content of the material in the thickness direction is uniform, repair of drying surface cracks is facilitated, and the occurrence of dark cracks is avoided. Further, in s5, in the cooling stage, when the difference between the temperature of the drying medium in the circulation branch path and the temperature of the drying medium in the circulation main path is less than 3 ℃, the second temperature adjusting body controls the temperature of the drying medium in the circulation branch path to rise, at this time, the second temperature adjusting body is in a heating state, and a distance is provided between the second temperature adjusting body and the surface of the material, so that the material can be subjected to steam ironing treatment similar to steam ironing by using the drying medium with still relatively high relative humidity in the later drying stage (the drying process in the cooling stage), and the surface flatness of the dried material can be improved.

In order to achieve the above object, a second embodiment of the present invention provides a drying device for performing the combined drying method, including a drying kiln body, wherein a first temperature adjustment unit, a steam humidity adjustment unit, a fluid power unit, and a control system are disposed in the drying kiln body, a second temperature adjustment unit is disposed in the drying kiln body, the second temperature adjustment unit includes a frame body, a plurality of second temperature adjustment bodies fixedly mounted on the frame body, and a pipeline communicating the plurality of second temperature adjustment bodies, the plurality of second temperature adjustment bodies are stacked, and at least one surface of the second temperature adjustment body is fixedly provided with a plurality of hollow partition strips, and the first temperature adjustment unit and the second temperature adjustment unit are heated by the same heat source.

In order to achieve the above object, a third embodiment of the present invention provides a drying device for performing the combined drying method, including a drying kiln body, wherein a first temperature adjustment unit, a steam humidity adjustment unit, a fluid power unit, and a control system are disposed in the drying kiln body, a second temperature adjustment unit is disposed in the drying kiln body, the second temperature adjustment unit includes a frame body, a plurality of second temperature adjustment bodies fixedly mounted on the frame body, and a pipeline communicating the plurality of second temperature adjustment bodies, the plurality of second temperature adjustment bodies are stacked, and at least one surface of the second temperature adjustment body is fixedly provided with a plurality of hollow partition strips, the first temperature adjustment unit is heated by a first heat source, and the second temperature adjustment unit is heated by a second heat source.

In summary, compared with the prior art, the invention has the beneficial effects that:

(1) the drying efficiency can be improved, and the formation of drying defects can be avoided;

(2) the water content monitoring and the steam pressure monitoring result are not depended on, so that the problems caused by monitoring errors are avoided;

(3) the surface smoothness of the dried material can be improved, the repair of dry surface cracks is facilitated, and the occurrence of dark cracks is avoided;

(4) the drying energy consumption is relatively low, and the whole drying process can reduce the drying energy consumption by at least 45%.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive exercise.

Fig. 1 is a schematic structural view of a drying apparatus according to embodiments 1 to 3 of the present invention;

fig. 2 is a schematic structural diagram of a second temperature adjustment unit according to embodiments 1 to 3 of the present invention.

In the figure: 100-a second temperature adjusting body, 200-a hollow parting strip, 300-a pipeline, 400-a frame body, 500-a drying kiln body, 600-a fluid power unit, 700-a first temperature adjusting unit, B-a test material, C1-a first dry bulb thermometer, C2-a second dry bulb thermometer, C3-a first wet bulb thermometer and C4-a second wet bulb thermometer.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Example 1: referring to fig. 1, the combined drying device includes a drying kiln body 500, wherein a first temperature adjusting unit 700 for adjusting and controlling a temperature of a drying medium, a steam humidity adjusting unit (not shown in the figure) for adjusting and controlling a humidity of the drying medium, a fluid power unit 600 for making the drying medium form a flow velocity, and a control system (not shown in the figure) are disposed in the drying kiln body 500. Specifically, the drying kiln body 500 is an aluminum alloy kiln body; the first temperature adjusting unit 700 is arranged at the top of the drying kiln body 500 and comprises an oil heating plate and a radiator positioned above the oil heating plate, the first temperature adjusting unit 700 is connected with a heat source outside the drying kiln body 500 and supplies heat by the heat source, and the heat source is any hot-pressing oil heating system in the prior art; the steam humidifying unit is any one of steam spraying systems in the prior art; the fluid power unit 600 comprises three fans which are positioned above the oil heating plate and between the radiators; the control system is a PLC control system.

Specifically, as shown in fig. 2, a second temperature adjusting unit for adjusting and controlling the temperature of the drying medium is disposed in the kiln body 500 of the drying kiln in the present embodiment, and the second temperature adjusting unit includes a frame body 400, a plurality of second temperature adjusting bodies 100 fixedly mounted on the frame body 400, and a pipeline 300 communicating with the plurality of second temperature adjusting bodies, wherein a plurality (for example, 5 layers) of the second temperature adjusting bodies 100 are stacked, and a plurality of hollow partition bars 200 are fixedly disposed on at least one surface of the second temperature adjusting bodies 100. In this embodiment, the second temperature controller 100 is a flat heat supply body, such as an oil-heating hot plate, the hollow spacers 200 are welded and fixed on two surfaces of the second temperature controller 100, the hollow spacers 200 are welded and fixed only on the lower surface of the second temperature controller 100 located at the top layer, and the hollow spacers 200 are welded and fixed only on the upper surface of the second temperature controller 100 located at the bottom layer. The plurality of second temperature control bodies 100 are heated by the same heat source as the first temperature control unit 700 through the extended line of the pipeline 300.

A first dry bulb thermometer C1 and a first wet bulb thermometer C3 are arranged on one kiln body wall of the drying kiln body 500 and are used for monitoring and feeding back the temperature and the relative humidity of the drying medium in the main drying medium circulation path, and a second dry bulb thermometer C2 and a second wet bulb thermometer C4 are arranged on one side of the hollow parting strip 200 and are used for monitoring and feeding back the temperature and the relative humidity of the drying medium in the branch drying medium circulation path.

The test material B of this example is a peach blossom heartwood blank purchased from the market, and has a specification of 930mm × 130mm × 23mm, and the actual treatment volume in the kiln is about 50m³. The test material B without layer is laid across above the hollow division bar 200 of the layer and forms a space between the upper and lower hollow division bars 200 and the upper and lower second temperature control bodies 100. The thickness of the hollow division bar 200 is 0.5cm to 2.0cm, the distance between the test material B and the second temperature control body 100 therebelow is 0.5cm to 2.0cm, the distance between the hollow division bar 200 above and below the test material B may be the same as or slightly larger than the thickness of the test material B, and generally, the distance between the test material B and the second temperature control body 100 thereabove is 0.5cm to 3.0 cm. For example, if the thickness of the hollow dividing bar 200 is 1.8cm and the distance between the upper and lower hollow dividing bars 200 in the same layer is 2.5cm, the test material B is spaced 1.8cm from the second temperature control body 100 below the test material B and 2.5cm from the second temperature control body 100 above the test material B. The transverse distance between the test materials B on the same layer is the same as the stacking mode in the prior art, for example, 0.5-1.0 cm.

The combined drying device is used for drying the test material B, and the test material B is stacked in the drying kiln body 500. In the drying process, the temperature of the drying medium is increased to 43 ℃ at the heating rate of 1.5 ℃/h, and the temperature is kept for 9 h; then heating to 53.5 +/-1.5 ℃ at the heating rate of 2.0 ℃/h, and keeping the temperature for 54h, wherein the humidity of a drying medium is controlled to be not more than 90% RH; the cooling speed of the drying medium is 2 ℃/h; the fluid power unit brings the drying medium to a flow velocity of 4 m/s.

In the other drying process, the drying medium is heated to 40 ℃ at the heating rate of 2.0 ℃/h and is kept warm for 10 h; then heating to 53.5 +/-1.5 ℃ at the heating rate of 2.5 ℃/h, and keeping the temperature for 60h, wherein the humidity of a drying medium is controlled to be not more than 86% RH; the cooling speed of the drying medium is 2.5 ℃/h; the fluid power unit brings the drying medium to a flow rate of 3 m/s.

In the other drying process, the drying medium is heated to 45 ℃ at the heating rate of 2.0 ℃/h and is kept warm for 8 h; then heating to 53.5 +/-1.5 ℃ at the heating rate of 2.0 ℃/h, and keeping the temperature for 48h, wherein the humidity of a drying medium is controlled not to exceed 92% RH; the cooling speed of the drying medium is 1.5 ℃/h; the fluid power unit brings the drying medium to a flow velocity of 5 m/s.

Example 2: embodiment 2 is different from embodiment 1 in that the first temperature adjusting unit is heated by the first heat source, and the second temperature adjusting unit is heated by the second heat source. The first heat source is a hot oil heat supply source, and the second heat source is a hot oil and cold oil switching heat supply source.

The combined drying device is used for drying the test material B, and the test material B is stacked in the drying kiln body 500. The drying process comprises the following drying stages:

s1, in a preheating stage, a first temperature regulating unit and a second temperature regulating unit enable a drying medium to be heated to 43 ℃ at a heating speed of 1.5 ℃/h;

s2, in a first heat preservation stage, when the temperature of a drying medium reaches 43 ℃, preserving heat for 9 hours;

s3, in a temperature rise stage, enabling the drying medium to rise to 51.5 +/-1.5 ℃ at a temperature rise speed of 2 ℃/h by the first temperature regulating unit and the second temperature regulating unit;

s4, in a second heat preservation stage, after the temperature of the drying medium reaches 51.5 +/-1.5 ℃, keeping constant temperature until the relative humidity of the drying medium reaches 90% RH, continuing to preserve heat for 54h after the relative humidity of the drying medium reaches the highest humidity, and simultaneously keeping the relative humidity of the drying medium at the highest humidity in a dehumidification mode;

and S5, in the cooling stage, after the relative humidity of the drying medium reaches the highest humidity, the first temperature regulating unit and the second temperature regulating unit enable the drying medium to be cooled to be below 40 ℃ at a cooling speed of 2 ℃/h, and the relative humidity of the drying medium is reduced by moisture removal.

Example 3: the difference between the embodiment 3 and the embodiment 2 is that in the second heat preservation stage, when the temperature of the drying medium in the circulation branch circuit is higher than that of the drying medium in the circulation main circuit by 3 ℃, the second temperature adjusting body controls the temperature of the drying medium in the circulation branch circuit to be reduced, so that the temperature difference between the drying medium in the circulation branch circuit and the drying medium in the circulation branch circuit does not exceed 3 ℃; in the s5, in the temperature reduction stage, when the difference between the temperature of the drying medium in the circulation branch and the temperature of the drying medium in the circulation main path is less than 3 ℃, the second temperature regulator controls the temperature of the drying medium in the circulation branch to be increased, and the temperature of the drying medium in the circulation branch is higher than the temperature of the drying medium in the circulation main path by 5 ℃ to 6 ℃.

The drying quality of examples 1 to 3 of the present application is shown in table 1.

TABLE 1 drying quality Table

The test materials of the control group 1 are the same as those of the examples 1 to 3, and a kiln type drying process is adopted in the same kiln body, and the specific drying process is as follows: keeping the temperature for 4h at 30 ℃, heating to 40 ℃ within 12h, heating to 45 ℃ again within 2h and keeping the temperature for 22h, heating to 55 ℃ within 10h and keeping the temperature for 24h, heating to 70 ℃ within 30h and keeping the temperature for 72h, cooling to 40 ℃ and taking out of the kiln.

The comparison group 2 adopts a common hot-pressing drying process; the control group 3 is an embodiment described in chinese invention patent CN 201910476778.2. The kiln drying and hot-pressing drying modes are different, and the comparison groups 2 and 3 are processed for 20 times (namely 4.8 m) by 1 8 laminating machines³Volume) of material recorded for dry defects, other non-dry defects, multiplied by 10 (about 48 m)³) And (4) performing conversion to obtain.

The non-drying defect is a defect not caused by drying, for example, surface roughness, wormhole, node shedding, and the like.

The foregoing description is for the purpose of illustration and is not for the purpose of limitation. Many embodiments and many applications other than the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego the subject matter and should not be construed as an admission that the applicant does not consider such subject matter to be part of the disclosed subject matter.