EP3784830A1

EP3784830A1 - Drier and method for operating a drier

Info

Publication number: EP3784830A1
Application number: EP19729172.7A
Authority: EP
Inventors: Wolf-Peter Graeser; Joachim Krause
Original assignee: Lavatec Laundry Technology GmbH
Current assignee: Lavatec Laundry Technology GmbH
Priority date: 2018-04-27
Filing date: 2019-04-25
Publication date: 2021-03-03
Anticipated expiration: 2039-04-25
Also published as: EP3784830B1; ES2949791T3; DK3784830T3; WO2019206383A1; DE102018206629A1; US11976409B2; FI3784830T3; US20210230792A1

Abstract

The invention relates to a drier comprising a receptacle (4) for the items to be dried, an air guide for guiding recirculated air (12) and/or fresh air (5) to the receptacle (4), a heating device (19) and at least one sensor (13, 17) for determining relative humidity and/or temperature, the air guide comprising at least one selection element (9, 11) so that the amount of recirculated air guided to the receptacle (4) can be varied using said selection element (9, 11). The drier according to the invention is characterized by comprising an open-loop or closed-loop controller so that the amount of recirculated air guided to the receptacle and/or the heating power of the heating device (19) can be controlled or adjusted during drying. The invention further relates to a method for operating a drier.

Description

DRYER AND METHOD FOR OPERATING A DRYER

The invention relates to a dryer with a receptacle for Trocknungsgut, an air guide for guiding circulating air and / or fresh air to the recording, a Fleizeinrichtung and at least one sensor for determining relative humidity and / or temperature, wherein the air guide comprises at least one adjustment, so in that the recirculated air portion guided to the receptacle can be changed via the adjusting element. The invention further relates to a method for controlling or regulating a dryer according to the invention.

Dryers of the type mentioned are known in practice and exist in different embodiments. Reference will be made, by way of example only, to the document WO 2016/184462 A1.

In general, after the washing process with mechanical dewatering, the residual water from the textiles is removed under the action of heat. Depending on the type of laundry, a tumble dryer is used in the drum dryer (tumbler) as a preparation for the mangling of flat linen or for the finishing of molded parts. Certain parts (e.g., toweling) undergo "full drying". Pre-drying and solid drying differ by the water content (residual moisture) of the laundry parts at the end of drying. Depending on the type of laundry and subsequent treatment, the final textile moisture content (water content based on the dry laundry) is between 35% and 50% (predrying) or 5% and 0% (full drying). A major problem in the removal of residual water under heat with the known dryers is the extremely unfavorable efficiency.

The desired textile residual moisture determined over the required drying time the drying energy demand and caused by the drying textile damage the life of the laundry parts and thus the economic situation of mostly small and medium-sized structured laundry. For heating the exhaust air dryers currently used in the laundries, the energy requirement values are up to 1.5 kWh / kg of dried textile. This, compared to the theoretically required for evaporation of water high heat energy demand is due to the fact that the porous material to be dried is heated by hot air, which is guided by blowers to the textiles and at the same time takes over the removal of the evaporated water. Due to the lower installation costs, the easier regulation of the heat energy supply and the lower energy input, gas-fired dryers have prevailed over steam-heated dryers. Electric heating is only used in small commercial machines or for household appliances

The damages caused by the drying are, in particular, textile damage such as changes in the textile dimensions, a reduction in the whiteness and the color as well as chemical damage to the fiber substrate. These textile damage occur in particular by "over-drying" of the laundry items (removal of the water contained in textiles at normal humidity, in cotton by 10%) at elevated temperature and drying time. Prolonged drying time - even at low temperatures - favors fiber abrasion due to intensive "drying mechanics".

The present invention is therefore based on the object, a dryer and a method for operating a dryer in such a way and further, that with structurally simple means a gentle drying at the lowest possible energy consumption is possible.

According to the invention the above object is achieved by the features of claim 1. Thereafter, the dryer in question with a receptacle for Trocknungsgut, an air guide for guiding circulating air and / or fresh air to the recording, a heater and at least one sensor for determining relative humidity and / or temperature, wherein the air guide comprises at least one adjustment in that the recirculated air fraction guided to the receptacle can be changed via the adjusting element, thereby in that a control or regulating device is arranged, so that the circulated air portion guided to the receptacle and / or the heating power of the heating device can be controlled or regulated during the drying process.

In accordance with the invention, it has first been recognized that the drying process can be considerably optimized with regard to energy efficiency and textile preservation if the circulated air portion and / or the heating power can be regulated or controlled during operation. Specifically, the recirculated air content and / or the heating power of a control or regulating device, taking into account the different drying phases be changeable, whereby it is achieved that the total drying at extremely high degree of saturation of the process air and the lowest possible air temperature is feasible. Due to the constructive design according to the invention, in addition to a high utilization of heat, it is achieved that the drying process is extremely gentle on the textile, since overheating of the material to be dried is avoided. It should be noted that the proportion of recirculated air within - for example in a hood - and / or outside - for example, in pipes - the device can be performed.

The term "fresh air" in the context of this invention refers to ambient air, which is the dryer, such as the recording or the burner supplied.

The term "process air" refers to the air contained in the receptacle during the drying process. "Exhaust air" is understood to mean the air discharged from the intake. If the exhaust air is returned to the intake and thus forms part of the process air, it is referred to as "circulating air".

The "drying material" may be textiles or goods made of other materials, such as rubber mats or mats made of polyamide pile.

The "recording" may be formed in a single dryer in particular as a drum. In an embodiment with several, for example, behind or modules arranged side by side, the recording of the entire device may be formed for example by the respective drums of the modules, ie also be present in a modular manner.

Advantageously, the adjusting element may be a ventilation flap and / or a circulating air blower. The ventilation flap can be arranged in such an air duct, that in the open position of the ventilation flap exhaust air is returned to the recording and thus serves as circulating air. In a particularly advantageous manner, the ventilation flap and possibly the air duct is designed such that in a completely open ventilation flap position, a recirculated air proportion of 100% and in a closed ventilation flap position a recirculation rate of 0% can be realized. Alternatively or additionally, a circulating air blower can be arranged in the air guide in order to promote exhaust air intake as circulating air.

In order to allow a particularly accurate adjustment of the recirculated air portion, it is conceivable that the ventilation flap position and / or the circulating air blower power is at least substantially continuously adjustable. By this design measure, a particularly energy-efficient control or regulation of the drying process is made possible. Specifically, it is possible that the ventilation flap by means of a servomotor or a cylinder-piston device (eg. Pneumatic cylinder) is operable.

In a further advantageous manner, it is conceivable for the sensor to be used for determining the relative exhaust air humidity of the exhaust air discharged from the input. This sensor may include a filter element to protect the sensor from lint. As a filter element, for example, a fabric filter or steel sintered element, in particular with a pore size of 5 pm serve. It should be noted at this point that the term "relative exhaust air humidity" is to be understood in the broadest sense, namely, the measurement of the relative air humidity can also take place in the interior of the receptacle and thus relate to the process air. Alternatively or additionally, a sensor for determining the surface temperature of the material to be dried can be arranged. For example, this may be an infrared sensor or any other temperature sensor. Also is it is possible that a combined temperature and humidity sensor is provided. It is also conceivable that a sensor for determining the input air temperature and / or the outlet air temperature is arranged. The inlet air is the air which is introduced into the receptacle, whereas the outlet air is the air which is discharged from the receptacle. It can thus be arranged any combination of the above sensors. In a modular design, the number and mode of operation of the sensors of the individual modules may differ from one another, so that the sensors are provided corresponding to the defined task of the modules. The inlet air temperature and / or the outlet air temperature can be taken into account in the control or regulation of the recirculated-air proportion and / or the heating power.

According to an advantageous embodiment, the control of the adjusting element, in particular the ventilation flap position and / or the circulating air blower, with the relative exhaust air moisture and / or with the surface temperature of the material to be dried as a measured variable and the recirculated air as a control variable. With such a construction, it is ensured that during operation the recirculated-air proportion can be adapted to the relevant, variable parameters, whereby a considerable improvement in the efficiency is accompanied and damage to the material to be dried is avoided.

Alternatively or additionally, it is furthermore conceivable that the control of the heating device takes place with the relative exhaust air humidity and / or the surface temperature of the material to be dried as the measured variable and the heating power as the control variable. Thus, the heat output of the burner is adaptable to the essential parameters that change during the drying process.

In a further advantageous manner, the receptacle can have a plurality of modules arranged one after the other and / or next to one another, which are configured in a suitable manner for heating, drying or cooling the material to be dried, in particular each module can have its own heating device. In this case, the recording can have two or more modules arranged one after the other and / or next to one another. This offers the possibility of carrying out individual process steps in a particularly efficient manner, the proportion of recirculated air and / or the heating power of the heater of each module during the drying process can be controlled. For example, a structure with a module for heating, one or more modules for drying, a module for controlling the moisture content of the item to be dried and a module for cooling the item to be dried are particularly efficient. Furthermore, the dryer can have at least one transport device assigned to a module for the further transport of the material to be dried from this module to another module. With such a transport device, a secure transport or a secure transfer of the material to be dried is made possible in the drying process effected by the modules.

In an advantageous embodiment, the air duct may be configured such that the circulating air supplied to a module is exhaust air of this module and / or exhaust air of at least one other module. In particular, it can be the exhaust air of a module arranged in front of it in the direction of transport of the material to be dried, preferably the module arranged directly in front of it or several modules arranged in front of it. Due to the at least partial use of exhaust air as circulating air, the heat contained in the exhaust air can be used in one or more other modules. Alternatively or in addition to such use of the exhaust air as supply air or recirculated air, the exhaust air can also be used as combustion air of the heating device, provided that the heating device is operated by means of a combustion process. In addition to such a mode of operation of the heating device, it is also possible to heat the air by means of steam or electrical energy-without a combustion process. In this case, an exhaust air of a module for the heater is not needed.

Alternatively or in addition to a utilization of the exhaust air of one or more modules as described above, heat from an exhaust air of a module or several modules can be arranged at least partially on an air intake and / or recirculation air, in particular in front of it, preferably directly in front of it arranged, module or more, in particular arranged in front of modules be transferable. Such a transfer process can be carried out by means of one or more heat exchangers, preferably air / air / heat exchangers. exchanger, done. This type of use of waste heat from an exhaust air differs due to a transmission means used - the heat exchanger - from a direct transfer of heat, as for example in a case when exhaust air of a module at least partially forms a supply air of another or several other modules. A heat exchanger can for example be integrated in a module or be directly associated with a module, for example to enable recirculation mode operation of the module. Alternatively or additionally, a heat exchanger or a plurality of heat exchangers may be provided, which are arranged in an air duct or integrated into an air duct, for example, if necessary, to preheat a supply air for a module by means of an exhaust air of a module.

In order to ensure a particularly good drying result and to ensure an efficient use of the required energy, a module for controlling the moisture content of the material to be dried can be arranged in front of a module for cooling the material to be dried. Such a control module can form the end of an arrangement of modules for heating and for drying, in order to check the moisture content before the drying material cools and, if necessary, to additionally perform a post-drying in the control module.

With regard to a particularly efficient use of required energy, a supply air of a module for controlling the moisture content of the material to be dried may at least partially be air, which is heated by means of a heat exchanger, preferably an air / air heat exchanger, the thermal energy from the exhaust air of a module for Heating the Trocknungsguts and / or from the exhaust air of another module or module for controlling the moisture content of the drying material itself refers. In this case, efficient use of energy can take place by supplying preheated supply air. In a particularly advantageous manner, the supply air to this control module is formed exclusively by preheated to the type described air.

One or more usually arranged as a completion of the arrangement of different modules module for cooling the drying material supply air or fresh air can be supplied from the installation room in which this module or modules are located or from outside the building.

In a further advantageous manner, it is conceivable that the air duct, which may be formed, for example, at least partially corresponding pipes, additional fans or fans. This makes it possible to support the air flow, so that a reliable operation of the dryer is ensured, especially in air ducts over long distances.

In a particularly advantageous embodiment, a transport device can be arranged between each two modules. The transport device may preferably have a conveyor belt or a chute or a slide chute. In the case of a chute or slide chute, a suitable height offset between the modules is useful so that the material to be dried passes from one module to the next module due to gravity. Possibly. A compressed air support can be provided which ensures a safe onward transport of the material to be dried. As an alternative to the aforementioned embodiments, the transport device may be formed as an internal mechanism of a module or integrated into a module. Such a transport device or mechanism can move the transported goods between modules by means of suitable gripping and / or guiding elements. When selecting a suitable transport device, the required amount of material to be transported can be taken into account.

With regard to a reliable feeding of the material to be dried to the receptacle, a drying material supply device can be arranged before the receptacle, which preferably has a weighing device for the material to be dried. This ensures that the dryer and, in concrete terms, the receptacle is loaded with a suitable amount of material to be dried. An overload of the dryer can be excluded thereby. To further optimize the drying process, it is possible that the control or regulating device as further parameters, the drying material (type of material to be dried), the heating temperature, the residual moisture content, the drying initial moisture, the loading rate, the filling ratio, the process air state variables, the fan power (a circulating air blower and / or a heater blower), the drum movement and / or the burner temperature taken into account. For example, the user can specify that the material to be dried is rubber mats or mats made of polyamide pile of a certain loading quantity. Corresponding parameters can for example be input via an input device and taken into account by the control or regulation device. In other words, the user may select a particular program for a dry good to perform the drying process. It is also conceivable that the adjusting element or the adjusting elements can be regulated as a function of the pressure prevailing in the air guide. For this purpose, one or more air pressure sensors can be arranged.

The underlying object is achieved with regard to the method by the features of the independent claim 12. Thereafter, a method for operating a dryer, in particular according to one of claims 1 to 11, with a receptacle for Trocknungsgut, an air guide for guiding circulating air and / or fresh air to the recording, a heater and at least one sensor for determining relative humidity and or temperature, wherein the air guide comprises at least one adjusting element, so that the guided to the intake air recirculation portion is changed via the adjusting element, characterized in that a guided to the intake air recirculation and / or the heating power of the heater during the drying process via a control or regulating device is controlled or regulated.

In accordance with the invention, it has been recognized that a considerable improvement in the efficiency can be achieved by adapting the recirculated-air portion and / or the heating power during the drying process. It should be noted that the device claims 1 to 11 also have features with a procedural expression. These can expressly also form part of the method according to the invention. The same applies to the above general description of the dryer according to the invention.

In an advantageous manner, during a heating phase, a high proportion of recirculated air, in particular between 90% and 100% recirculated air and a small proportion of fresh air, in particular between 0% and 10% fresh air, are conducted to the receptacle. Alternatively or additionally, the recirculated air portion during a drying phase in dependence on the measured relative exhaust air moisture is reduced and / or the heating power of the heater is reduced. Furthermore, it is possible that during a cooling phase, a low proportion of recirculated air, in particular from 0% to 10% and a high proportion of fresh air, in particular from 90% to 100%, are conducted to the receptacle. If the receptacle has several modules, it is possible that one or more modules only perform the heating phase or the drying phase or the cooling phase of the drying process.

With regard to a gentle and efficient drying, it may be provided that the duration of the drying phase and / or the reduction of the recirculated air portion during the drying phase is adjusted taking into account at least one external parameter. The external parameters may be the type of material to be dried, the heating temperature, the drying residue moisture, the initial charge moisture content, the charge quantity, the filling ratio, process air state variables, the blower output (a circulating air blower and / or a fan heater), the drum movement and / or the burner temperature.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, on the one hand to the claims 1 and 12 subordinate claims and on the other hand to the following description of preferred embodiments of the invention with reference to the drawing reference. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawings will also In general, preferred embodiments and further developments of the teaching explained. In the drawing show

1 shows the typical course of the tissue temperature as a function of the drying time in a drying process,

Fig. 2 shows a schematic, sectional view of a first

Embodiment of a dryer according to the invention for carrying out the method according to the invention,

Fig. 3 shows a schematic, perspective view of a second

4 shows in a schematic, lateral representation of the exemplary embodiment according to FIG. 3,

Fig. 5 shows in a schematic, side and partially cut

Representation of the embodiment of FIG. 3,

FIG. 6 shows a schematic plan view of the exemplary embodiment according to FIG. 3.

Fig. 1 shows the typical temporal temperature profile in the drying material for the duration of drying, wherein the fabric temperature is plotted as a function of the drying time. Evident are the three phases 1, 2, 3 of the drying process. In the first phase 1, the temperature rises rapidly to the value of the evaporation temperature (cooling limit temperature) in order to keep it constant during the course of the second phase 2 as long as the moisture is evaporated from the surface of the textile. In the third phase 3, the residual moisture from the capillaries of the textiles is evaporated, which leads to a sharp increase in the temperature up to the hot air level. These Phase indicates that the drying process is completed, the heat supply stopped and the cool-down can be initiated.

Fig. 2 shows a first embodiment of a dryer according to the invention. The dryer is designed as a single dryer and has a receptacle 4 for the drying material, not shown. The receptacle 4 may be formed as a drum. The receptacle 4, fresh air 5 can be supplied from outside the device, which is guided transversely through the receptacle 4 and withdraws there as process air 6 the drying material moisture. The exhaust air 7 discharged from the receptacle passes through a lint filter 8. In the flow direction of the exhaust air 7, a circulation fan 9 and a moisture sensor 10 are arranged downstream of the lint filter 8. By this arrangement it is avoided that the moisture sensor 10 is full of lint. However, it is also possible to arrange the moisture sensor 10 in the flow direction before the lint filter 8.

Furthermore, a ventilation flap 11 is shown in FIG. If the ventilation flap 11 is closed, the exhaust air 7 is led out of the dryer. In the case of complete or partial opening of the ventilation flap 11, the exhaust air 7 can be supplied in whole or in part as circulating air 12 of the receptacle 4.

In the device shown in Fig. 2, which is suitable for carrying out the method according to the invention, the position of the venting flap 11 and / or the performance of the circulating air blower 9 in dependence on the measured with the humidity sensor 10 humidity of the exhaust air 7 during operation be adjusted. Furthermore, it is conceivable that in the receptacle 4, a temperature sensor 13 is arranged, which serves to determine the surface temperature of the material to be dried. Also, a sensor for determining the input air temperature and / or a sensor for determining the output air temperature can be provided.

FIGS. 3 to 6 show, in different schematic representations, a further exemplary embodiment of a device according to the invention which is suitable for carrying out a method according to the invention. at In this embodiment, the receptacle 4 is formed by a plurality of successively arranged modules 14, 14 ', 14 ", for example, for heating, drying or cooling of the material to be dried. The individual modules 14, 14 ', 14 "can be designed according to the embodiment shown in Fig. 2, so that reference is made to the relevant embodiments. In such a configuration, the receptacle 4 of the entire device can be formed by the individual receptacles or drums of the modules 14, 14 ', 14 ".

It is also apparent from FIGS. 3 to 6 that fresh air can be passed to the individual modules via a fresh air duct 15. Furthermore, each module has a circulating air guide 16, via which the intake 4, that is, each module 14, 14 ', 14 ", can be supplied with circulating air, namely by regulating or controlling the adjusting elements (not illustrated). The exhaust air of the respective module 14, 14 ', 14 "can be removed via an exhaust air duct 21.

Furthermore, a heat exchanger 17 is arranged, via which the heat from the exhaust air can be transmitted to the supply air.

To further improve energy efficiency, the first module 14 has a Heizluftzuführung 18, via which the heater 19 can be supplied with fresh air, which can be preheated via the heat exchanger 17. It is conceivable that all modules 14, 14 ', 14 "have a corresponding Heizluftzuführung 18.

Before the first module 14, a Trocknungsgut feed is arranged, via which the module 14 is loaded with the Trocknungsgut. Between the modules 14, and module 14 'and between module 14' and module 14 ", a transport device 20 is arranged for further transport of the material to be dried.

Due to the modular design of the device, the drying material can be heated, for example in the first module 14, ie the heating phase takes place in this module 14. In the second module 14 ', the actual drying of the material to be dried can take place, ie the drying phase takes place in this module 14'. In the last module 14 ", for example, the cooling of the material to be dried can take place, ie the cooling phase takes place. The the individual modules 14, 14 'and 14 "supplied recirculated air can be done during the drying process in dependence on the measured humidity and / or surface temperature of the material to be dried. Alternatively or additionally, the heating power of the heating devices of the modules 14, 14 'and 14 "can be adapted as a function of these measured values.

With regard to further advantageous embodiments of the device according to the invention and of the method according to the invention, reference is made to avoid repetition to the general part of the description and to the appended claims.

Finally, it should be expressly pointed out that the above-described embodiments of the device according to the invention and of the method according to the invention merely serve to discuss the claimed teaching, but do not restrict it to the exemplary embodiments.

LIST OF REFERENCE NUMBERS

1 first phase

2 second phase

3 third phase

4 recording

5 fresh air

6 process air

7 exhaust air

8 lint filter

9 circulating air blower

10 humidity sensor

11 ventilation flap

12 circulating air

13 temperature sensor, 14 ', 14 "module

15 fresh air supply

16 circulating air supply

17 heat exchangers

18 heating air supply

19 heating device

20 Transport device 21 Exhaust air duct

Claims

1. dryer with a receptacle (4) for Trocknungsgut, an air guide for guiding circulating air (12) and / or fresh air (5) to the receptacle (4), a Fleizeinrichtung (19) and at least one sensor (13, 17) for Determination of relative humidity and / or temperature, wherein the air guide comprises at least one adjusting element (9, 11), so that the recirculated air portion guided to the receptacle (4) can be changed via the adjusting element (9, 11),

That is, a control or regulating device is arranged, so that the recirculated-air portion and / or the Fleizleistung of the Fleizeinrichtung (19) led to the admission can be controlled or regulated during the drying process.

2. Dryer according to claim 1, characterized in that the adjusting element as a ventilation flap (11) and / or as a circulating air blower (9) is formed.

3. Dryer according to claim 2, characterized in that the ventilation flap position and / or the Umluftgebläseleistung is at least substantially continuously variable.

4. Dryer according to one of claims 1 to 3, characterized in that the sensor (10) for determining the relative exhaust air humidity of the input (4) discharged exhaust air (7) is used.

5. Dryer according to one of claims 1 to 4, characterized in that the sensor (13) for determining the surface temperature of the material to be dried and / or for determining an input air temperature and / or an outlet air temperature is used.

6. Dryer according to claim 4 or 5, characterized in that the regulation of the adjusting element (9, 11) takes place with the relative exhaust air humidity as a measured variable and the recirculated air as a control variable.

7. Dryer according to one of claims 4 to 6, characterized in that the control of the adjusting element (9, 13) with the surface temperature of the material to be dried as a measured variable and the recirculated air as a control variable.

8. Dryer according to one of claims 4 to 7, characterized in that the control of the heating device (19) with the relative exhaust air moisture and / or the surface temperature of the material to be dried as a measured variable and the heating power as a manipulated variable.

9. Dryer according to one of claims 1 to 8, characterized in that the receptacle (4) has a plurality of successively and / or juxtaposed modules (14, 14 ', 14 ") for heating, drying or cooling of the material to be dried and that at least one Module (14, 14 ', 14 ") is associated with a transport device (20) for further transport of the drying material from this module (14, 14', 14") to another module (14, 14 ', 14 ").

10. Dryer according to claim 9, characterized in that the air guide is designed such that it in the one module (14, 14 ', 14 ") supplied circulating air (12) to exhaust air (7) of this module (14, 14' , 14 ") and / or exhaust air (7) of at least one other module (14, 14 ', 14") acts.

11. Dryer according to one of claims 1 to 10, characterized in that the control or regulating device as further parameters, the drying material and / or the heating temperature and / or the Trocknungsgutrest- moisture and / or the Trocknungsgutanfangsbefuchte and / or the loading amount and / or the filling ratio and / or process air state variables and / or the fan power and / or the drum movement and / or the burner temperature taken into account.

12. A method for operating a dryer, in particular according to one of claims 1 to 11, with a receptacle (4) for Trocknungsgut, an air guide for guiding circulating air (12) and / or fresh air (5) to the receptacle (4), a Heating device (19) and at least one sensor (10, 13) for determining relative humidity and / or temperature, wherein the air duct at least an adjusting element (9, 11), so that the recirculated air portion guided to the receptacle (4) is changed via the adjusting element (9, 11),

That is, a recirculated-air portion conducted to the receptacle (4) and / or the heating power of the heating device (19) are controlled or regulated by a control or regulation device during the drying process.

13. The method according to claim 12, characterized in that during a heating phase, a high recirculated air, in particular between 90% and 100% recirculated air and a small proportion of fresh air, in particular between 0% and 10% fresh air, to the receptacle (4). is directed.

14. The method according to claim 12 or 13, characterized in that the recirculated air content is reduced during a drying phase in dependence on the measured relative exhaust air humidity and / or the heating power of the heating device (19) is reduced.

15. The method according to any one of claims 12 to 14, characterized in that during a cooling phase, a small proportion of recirculated air, in particular from 0% to 10% and a high proportion of fresh air, in particular from 90% to 100%, to the receptacle (4) is passed ,

16. The method according to any one of claims 12 to 15, characterized in that the duration of the drying phase and / or the reduction of the recirculated air content during the drying phase is adjusted taking into account at least one external parameter.

17. The method according to claim 16, characterized in that as an external parameter, the drying material and / or the heating temperature and / or the Trocknungsgutrestfeuchte and / or the Trocknungsgutanfangsfeuchte and / or the loading amount and / or the filling ratio and / or Prozeßluftzustands- sizes and / or the blower power and / or the drum movement and / or the burner temperature is used.