Dryer and method for operating a dryer

Abstract

A disclosed dryer includes a receptacle configured to contain material to be dried, an air duct configured to route recirculating air and/or fresh air to the receptacle, a heating device configured to heat the recirculating air, and at least one sensor. The sensor is configured to determine a relative humidity and/or temperature, and the air duct includes at least one adjusting element configured to modify a portion of recirculating air routed to the receptacle. The dryer further includes a control or regulating device configured to control or regulate the portion of recirculating air routed to the receptacle and/or a heating capacity of the heating device during a drying process. A disclosed method includes controlling a portion of recirculating air routed to the receptacle and/or a heating capacity of the heating device. Further, a mixture of recirculating air and fresh air are varied during heat-up, drying, and cool-down phases.

Claims

1. A dryer comprising: a receptacle configured to contain material to be dried; an air duct configured to route recirculating air and/or fresh air to the receptacle; a heating device configured to heat the recirculating air; at least one sensor configured to determine a relative humidity and/or temperature, wherein the air duct comprises at least one adjusting element configured to modify a portion of recirculating air routed to the receptacle; and a control or regulating device configured to control or regulate the portion of recirculating air routed to the receptacle and/or a heating capacity of the heating device during a drying process, wherein the control or regulating device is further configured to control the adjusting element to: route, during a heat-up phase, a first portion of recirculating air and a second portion of fresh air to the receptacle, wherein the first portion is a high portion and the second portion is a low portion; route, during a cool-down phase, the first portion of recirculating air and the second portion of fresh air to the receptacle, wherein the first portion is a low portion and the second portion is a high portion; reduce, during a drying phase, the first portion of recirculating air, based on a measured relative exhaust air humidity and/or based on a heating capacity of the heating device.

2. The dryer according to claim 1, wherein the adjusting element comprises a ventilation flap and/or a recirculating air blower.

3. The dryer according to claim 2, wherein a position of the ventilation flap and/or an output of the recirculating air blower is continuously adjustable.

4. The dryer according to claim 1, wherein the sensor is configured to determine a relative humidity of exhaust air discharged from the receptacle.

5. The dryer according to claim 1, wherein the sensor is configured to determine a surface temperature of the material to be dried and/or to determine an input air temperature and/or an output air temperature.

6. The dryer according to claim 4, wherein the control or regulating device controls the adjusting element to adjust the portion of recirculating air based on a determined relative exhaust air humidity.

7. The dryer according to claim 5, wherein the control or regulating device controls the adjusting element to adjust the portion of recirculating air based on a determined surface temperature of the material to be dried.

8. The dryer according to claim 4, wherein the control or regulating device controls the heating capacity of the heating device based on a determined relative exhaust air humidity.

9. The dryer according to claim 1, wherein the receptacle further comprises: a heating device configured to heat the material to be dried; a drying device configured to dry the material to be dried; a cooling device configured to cool the material to be dried; and a transport device configured to transport the material to be dried between at least at least a first and a second one of the heating device, the drying device, and the cooling device, wherein the heating device, the drying device, and the cooling device are positioned one after another along a direction in which material to be dried is transported.

10. The dryer according to claim 9, wherein the air duct is configured to provide the recirculating air as exhaust air from at least a first one to a second one of the heating device, the drying device, and the cooling device.

11. The dryer according to claim 2, wherein the receptacle is configured as a rotating drum, and wherein the control or regulating device controls or regulates the portion of recirculating air routed to the receptacle and/or the heating capacity of the heating device based on one or more parameters, the parameters including: a type of material to be dried; a heater temperature; a residual moisture of the material to be dried; a starting moisture of the material to be dried; a load quantity of material to be dried; a filling ratio of the receptacle; an air temperature or relative humidity; a blower capacity; and a motion of the rotating drum.

12. A method of operating a dryer, the dryer comprising a receptacle configured to contain a material to be dried, an air duct configured to route recirculating air and/or fresh air to the receptacle, a heating device configured to heat the recirculating air, a control or regulating device, and at least one sensor configured to determine relative humidity and/or temperature, wherein the air duct comprises at least one adjusting element configured to modify a portion of recirculating air routed to the receptacle, the method comprising: controlling during a drying process, via the control or regulating device, a portion of recirculating air routed to the receptacle and/or a heating capacity of the heating device, wherein controlling includes: routing, during a heat-up phase, a first portion of recirculating air and a second portion of fresh air to the receptacle, wherein the first portion is a high portion and the second portion is a low portion; routing, during a cool-down phase, the first portion of recirculating air and the second portion of fresh air to the receptacle, wherein the first portion is a low portion and the second portion is a high portion; measuring a relative exhaust air humidity; reducing, during a drying phase, the first portion of recirculating air, based on a measured relative exhaust air humidity and/or based on a heating capacity of the heating device.

13. The method according to claim 12, further comprising: wherein during the heat-up phase the first portion of recirculating air includes 90% to 100% recirculating air, and the second portion of fresh air includes 0% to 10% fresh air.

14. The method according to claim 12, wherein during the cool-down phase the first portion of recirculating air includes 0% to 10% recirculating air, and the second portion of fresh air includes 90% to 100% fresh air.

15. The method according to claim 12, further comprising: controlling a duration of the drying phase and/or the reduction in the first portion of recirculating air based on at least one external parameter.

16. The method according to claim 15, wherein the receptacle is configured as a rotating drum, and wherein the at least one external parameter is chosen from parameters including: a type of material to be dried; a heater temperature; a residual moisture of the material to be dried; a starting moisture of the material to be dried; a load quantity of material to be dried; a filling ratio of the receptacle; an air temperature or relative humidity; a blower capacity; and a motion of the rotating drum.

17. The dryer according to claim 5, wherein the control or regulating device controls the heating capacity of the heating device based on a determined surface temperature of the material to be dried.

Description

(1) FIG. 1 shows the typical curve of the fabric temperature as a function of the drying time during a drying process;

(2) FIG. 2 shows a schematic, sectional view of a first exemplary embodiment of a dryer according to the disclosure for implementing the method according to the disclosure;

(3) FIG. 3 shows a schematic, perspective view of a second exemplary embodiment of a dryer according to the disclosure for implementing the method according to the disclosure;

(4) FIG. 4 shows a schematic, lateral view of the exemplary embodiment according to FIG. 3;

(5) FIG. 5 shows a schematic, lateral, and partially sectional view of the exemplary embodiment according to FIG. 3;

(6) FIG. 6 shows a schematic, top view of the exemplary embodiment according to FIG. 3;

(7) FIG. 1 shows the typically chronological temperature curve in the material to be dried for the duration of the drying, wherein the fabric temperature is applied as a function of the drying time. The three phases 1, 2, 3 of the drying process can be seen. In the first phase 1, the temperature quickly increases to the value of the evaporation temperature (cooling limit temperature) in order to subsequently keep this temperature constant over the course of the second phase 2 as long as the moisture is being evaporated from the surface of the textile. In the third phase 3, the residual moisture is evaporated from the capillaries of the textiles, which leads to a strong increase in the temperature up to the level of hot air. This phase indicates that the drying process has ended, the supply of heat is stopped, and the cool-down can be initiated.

(8) FIG. 2 shows a first exemplary embodiment of a dryer according to the disclosure. The dryer is formed as a single dryer and has a receptacle 4 for the material to be dried, which is not shown. The receptacle 4 can be formed as a drum in this case. Fresh air 5 can be supplied to the receptacle 4 from outside of the device, which is guided transversely through the receptacle 4 and removes moisture there from the material to be dried as process air 6. The exhaust air 7 discharged from the receptacle passes through a lint filter 8. When viewed in the direction of flow of the exhaust air 7, a recirculating air blower 9 as well as a moisture sensor 10 are arranged downstream of the lint filter 8. This arrangement prevents the moisture sensor 10 from becoming full of lint However, it is also possible to arrange the moisture sensor 10 upstream of the lint filter 8, as viewed in the direction of flow.

(9) Furthermore, a ventilation flap 11 is shown in FIG. 2. If the air flap 11 is closed, the exhaust air 7 is routed out of the dryer. If the air flap 11 is completely or partially open, the exhaust air 7 can be supplied, wholly or partially, to the receptacle 4 as recirculating air 12.

(10) With the device shown in FIG. 2, which is suitable for executing the method according to the disclosure, the position of the air flap 11 and/or the capacity of the recirculating air blower 9 can be varied during operation as a function of the humidity of the exhaust air 7 measured with the moisture sensor 10. Furthermore, it is conceivable that a temperature sensor 13, which is used to determine the surface temperature of the material to be dried, is arranged in the receptacle 4. A sensor can also be provided for determining the input air temperature and/or a sensor for determining the output air temperature.

(11) FIGS. 3 to 6 show, in various schematic views, a further exemplary embodiment of a device according to the disclosure, which is suitable for implementing a method according to the disclosure. In this exemplary embodiment, the receptacle 4 is formed by several devices 14, 14, 14, arranged after one another, for example for heating, drying, or cooling of the material to be dried. The individual devices 14, 14, 14 in this case may be formed according to the exemplary embodiment shown in FIG. 2 to the extent that reference is made to the related designs. With such an embodiment, the receptacle 4 of the entire device can be formed by the individual receptacles and/or drums of the devices 14, 14, 14.

(12) Furthermore, FIGS. 3 to 6 show that fresh air can be supplied to the individual devices via a fresh air duct 15. Furthermore, each device has a recirculating air duct 16, by which recirculating air can be supplied to the receptacle 4, i.e. to each device 14, 14, 14, in that specifically the adjusting elements, which are not shown, are regulated and/or controlled. The exhaust air of the respective device 14, 14, 14 can be dissipated via an exhaust air duct 21.

(13) Furthermore, a heat exchanger 17 is arranged, by which the heat from the exhaust air can be transferred to the infeed air.

(14) In order to further improve the energy efficiency, the first device 14 has a hot air supply 18, by which the heating mechanism 19 can be supplied with fresh air, which can be preheated via the heat exchanger 17. In this case, it is conceivable that all devices 14, 14, 14 have a corresponding hot air supply 18.

(15) An infeed for the material to be dried is arranged upstream of the first device 14, the device 14 being loaded with the material to be dried via said infeed. A transport mechanism 20, for further transport of the material to be dried, is arranged between device 14 and device 14, as well as between device 14 and device 14.

(16) Due to the modular design of the device, the material to be dried can be heated, for example, in the first device 14, i.e. the heat-up phase takes place in this device 14. The actual drying of the material to be dried takes place in the second device 14, i.e. the drying phase takes place in this device 14. The cooling of the material to be dried, for example, can take place in the last device 14, i.e. the cool-down phase takes place. The portion of recirculating air supplied to the individual devices 14, 14, and 14 can occur during the drying process as a function of the measured air humidity and/or surface temperature of the material to be dried. Alternatively or additionally, the heating capacity of the heating mechanisms of devices 14, 14, and 14 can be varied as a function of these measured values.

(17) With regard to other advantageous embodiments of the device according to the disclosure and of the method according to the disclosure, to avoid repetition, reference is made to the general part of the description and also to the accompanying claims.

(18) Finally, it is expressly pointed out that the above-described exemplary embodiments of the device according to the disclosure and of the method according to the disclosure serve only to explain the claimed teaching, but do not restrict it to the exemplary embodiments.

LIST OF REFERENCE NUMERALS

(19) 1 First phase

(20) 2 Second phase

(21) 3 Third phase

(22) 4 Receptacle

(23) 5 Fresh air

(24) 6 Process air

(25) 7 Exhaust air

(26) 8 Lint filter

(27) 9 Recirculating air blower

(28) 10 Moisture sensor

(29) 11 Ventilation flap

(30) 12 Recirculating air

(31) 13 Temperature sensor

(32) 14, 14, 14 Device

(33) 15 Fresh air infeed

(34) 16 Recirculating air infeed

(35) 17 Heat exchanger

(36) 18 Hot air infeed

(37) 19 Heating mechanism

(38) 20 Transport mechanism

(39) 21 Exhaust air duct