DE102013018558A1 - Method for controlling the heat input in tumble dryers - Google Patents

Abstract

The invention relates to a method for controlling the heat input in tumble driers by means of a regulation of the energy task of the changed over time air demand by regulating the air volumes. To do this in a dryer consisting of a pipe guide for transporting the air volumes via a heating stage, a drum for receiving the laundry, a fan for building the induced draft and a pipe for exhaust air and parallel out pipeline means with flaps with an involvement in the induced draft for distribution To reach the air volumes, the valves of the pipes are controlled by a temperature value by means of a guided by a temperature sensor controller in the exhaust air, the temperature value is selected as the limit value for each flap a limit and upon reaching individual limits by actuators by closing the flap, the amount of air and reduces the energy input in proportion to the sealed piping. This regulates the energy task over time.

Description

The invention relates to a method for controlling the heat input in tumble dryers, according to the preamble of claim 1 and a drying method for laundry according to claim 10.

State of the art

At a time of energy transition and the search for technical solutions to save energy in laundries, from convective drying in which the drying energy is supplied via a heated air stream and in convective drying in sorts the demand for air starting with the heating, evaporation and post-drying proportionally decreases the residual water and less air is required at the laundry to carry out the drying, known that changes the energy consumption of the laundry over the period until the end of drying and the energy losses in the hot exhaust air despite less energy consumption with a reduction increase the temperature of the heated air. Next, opportunities from the operation of these commercial dryer known that when too fast heating of the laundry, the heat is returned and the energy consumption in the course of drying z. B. is reduced by closing a steam valve. Further, energy-saving measures of these dryers in achieving the final drying are known in such a way that the temperatures are determined within the dryer and the supply of energy is stopped with the achievement of a certain temperature on the product. In this case, the drying process is controlled and terminated either empirically or empirically based on the measurement of different drying parameters. This approach is either too inaccurate to control the energy consumption so that it is low, which is important in the energy transition, or the amount of measurement technology is so high that the measurement technology for retrofitting is not suitable in the energy transition.

Furthermore, there are many dryers, some over 30 years, in commercial use, in which a rated capacity for drying at a certain amount of air is set up, but are loaded in daily operations with smaller items and changing laundry items. As energy consumption continues to be very high, the energy transition will require a simple process to reduce the energy consumption of older dryers operating for several years in daily operation.

The invention relates to the convective drying of textile-containing material, fabrics and laundry in dryers, the equipment for performing the drying and the timing and a method for controlling the convective drying associated equipment air in the drying of laundry items in commercial dryers in order to use less energy in these dryers and to provide older dryers with simpler processes with less energy consumption. Another goal is to achieve CO ₂ savings.

A clothes dryer and a method for controlling the heating power as a function of the progress of the drying is known from the document DE 103 02 973 B3 known. This heat output is controlled as a function of the time course of the moisture level by means of a control device in a tumble dryer. Disadvantage is that this control direction controls a heating capacity, defined in kW, and that the convective heat carrier, with which the energy is transported and the heat losses are not controlled by the air.

A clothes dryer and a method for treating laundry in conjunction with a control valve and a heater in a supply air line using a suction pump in which the moisture evaporates at a negative pressure, is from the document DE 39 03 186 A1 known. Disadvantage is the negative pressure on the laundry and the high energy consumption for the pressure increase (compression) of the evaporated water, H ₂ O.

A drier and a method for treating a material with a heating stage and a controllable throttle to reduce the speed in the process air stream has become known from the document 10 2006 003 817. This controllable throttle is used in the first heating phase to increase the residence time of the air and opened in the subsequent drying phase to a different extent. The drying of laundry by this method is disadvantageous depending on the residence time of the air determined by the throttle. Disadvantage is that the residence time is increased at the highest heat demand. Another disadvantage: the throttle is used to set the temperature and not the amount of energy in the process air.

A method of controlling and controlling a drying process in a gas heated dryer to form control factors from various drying parameters is disclosed in the document DE 10 2012 008 193 A1 become known, with a dryer with a recirculation damper and a variable flap position, through which the influx of heated air is adjusted. This drying-determining control by means of a recirculating-air flap has the disadvantage that the factors used to control the flap are not based on fluidic parameters and in particular the change in the pressures. The disadvantage is that fresh air is sucked in closed recirculation damper via the burner by a negative pressure and after the pressure increase is blown on the pressure side of the fan as exhaust air, but in the formed with open flap position flow channel, the absolute pressures before the exhaust air outlet and the influx of heated air equalize , Disadvantage is in a highly complex formation of the factors when the burner and the influx of air is not connected to the suction side of the fan, but to work against an increased pressure in the open flap position. Disadvantage is: the reversal of the flow in the combustion chamber and the release of vapors, combustion gases and toxic carbon monoxide by the pressure increase with the flap open. Another disadvantage: a failure of the control option.

A dryer and a method for post-drying for the saving of energy by means of limiting the amount of air and increasing the residence time of the air flow to improve the heat exchange is from the document DE 10 2012 002 249 in which, for the after-drying in a Zuluftinstallation the air flow is limited by higher pressure losses in pipeline means. This method is associated with the commercial application with the disadvantage that for a certain time provided for the after-drying, the air flow is reduced and the residence time is increased. Disadvantage is that the air flow is constant in each case and that the air flow is tuned in the transitional period between main evaporation and post-drying and in the evaporation phase is not changeable with the necessary heat transfer to carry out the drying. Disadvantage is the high energy consumption with changing evaporation z. B. at part load.

The object of the invention is, starting from the cited prior art in the control of convective cycle dryers on the temperatures before drying and a drying guide after the residence time and drying by changing the circulating air and shortening the residence time of the primary energy and the long service life single dryer sized at the relatively short energy transition and the item size of individual laundry items to propose further measures to allow better use of energy supplied, better flow of laundry and lower energy consumption over the duration of drying. Another task is to propose by appropriate measures a lower demand for energy and thus less primary energy consumption, a reduction in the cost of energy and a reduction of CO ₂ emissions and to show possibilities for reproducible implementation of the measures on existing plants and new installations.

The object is achieved on the basis of a prior art in the regulation of heat input in dryers for laundry by the method for controlling the heat application and the features in the characterizing part of claim 1 and by the features of the method according to claim 10.

Advantageous developments and embodiments of the invention are possible by the measures mentioned in subclaims 2 to 9.

An essential feature of the invention is accordingly in a method for controlling the heat in tumble driers, consisting of parallel piping means with flaps with an inclusion in the induced draft for the distribution of air volumes, and a temperature sensor for diagnosing changes in the exhaust air, that by means of a temperature sensor guided control the valves of the pipes are controlled by a temperature value, the temperature value is selected as a limit value for each flap as a limit and when reaching individual limits by adjusting motors by closing the flap, the amount of air and the energy input proportional to the sealed pipes are reduced and in particular that at Falling below the limit temperature by the actuator containing a return spring by re-opening the flap, the amount of air and the energy task can be increased.

It is true that in a convective drying of the temperature of the hot air and the residence time of the air in the dryer, although the specific heat transfer per kg of air depends, but that the amount of heat that is supplied, and the energy task in the dryer of the Air flow so the Air quantity is determined, which is fed via the suction to the dryer. Accordingly, the heat duty over the duration of the drying is controlled by a change in the amounts of air and the size of the air quantities are regulated by the cooling of the air to a temperature in the exhaust air as the maximum or limit.

Accordingly, the method for controlling the heat input in tumble driers, in which wet items are treated with hot air and the energy requirement with hot air is regulated by the change in air demand over time by means of a regulation of air volumes,
consisting of a pipe guide for transporting the air volumes via a heating stage, a drum for receiving the laundry, a fan for building the induced draft and a pipe for exhaust air, that the valves of the pipes are controlled by a temperature value guided by the exhaust air sensor, the Temperature value is selected as the limit value for each flap as a limit and when reaching individual limits by servomotors by closing the flap, the amount of air and the energy duty proportional to the sealed pipes are reduced and in particular falls below the limit temperature by a reset spring-containing actuator by re-opening the door the amount of air and the energy task are increased.

A significant advantage is that when individual limit values are reached by means of servomotors, the closing of the flap reduces the air flow (quantities) and the energy input proportionally to the closed pipelines. The advantage is the simplicity and that one (1) temperature determines the energy task. Another advantage that the temperature value is adjustable.

Another advantage of the control function is that when the limit falls below the threshold, the original energy task becomes effective again when the damper is opened. Advantage is the high change of the energy task by switching off and on of the hot air.

A significant advantage in the function of the temperature sensor in the exhaust air is that when filled with fewer items of laundry, the exhaust air-side limit is reached earlier. The advantage is that the energy task is reduced earlier. Another advantage: the saving of energy and the prevention of overheating of the laundry.

An advantageous embodiment of the invention is given by the fact that falls below the limit temperature by the return spring-containing actuator motor by re-opening the flap of the air flow (air volumes) and the energy task can be increased. The advantage is that the temperature of the limit value is regulated by opening and closing the flap. The advantage is the simplicity of the controller. The advantage is that the control function is only dependent on 1 value. Another advantage consists in the treatment function of the laundry items in that the items of laundry are ventilated more vigorously when opening the flap. The advantage is a "flaky" laundry quality.

Another advantage is the simplicity in the technical structure: by a return spring in the drive motor of the flap.

An advantageous embodiment of the invention is given by the fact that the volume of air and the energy application are regulated by a volume flow controller in the open pipes. The advantage is that the original air volume of the open pipeline is not changed. The advantage is the reproducibility of the settings.

Advantage is the high efficiency of the control and the rule width of the changes. Another advantage: the high frequency of the fluctuations without the change of the hot air.

A preferred development of the invention consists in the higher limit values in that, when the higher limit value is reached by means of the servo motor containing a return spring, the energy input is regulated proportionally to the air flow. The advantage is the increase in the control function. Another advantage: a doubling of the control effect z. B. to 50% with 2-fold reduction in airflow by 25%.

Advantage is the dependence of the energy task in% values of the air flow and the amount of air. Another advantage: The simplicity of planning through parallel piping.

Another advantage is the simple logic of the procedure: "If the value is too high, the energy input is reduced and, conversely, it is increased".

An advantageous embodiment of the method is given in the operability of the method that the limits of the flaps are set as the setpoint on control buttons of the controller. Advantage is the simple adaptation of the limits z. B. in the drying of sensitive fluffy blankets.

An advantageous embodiment of the invention is that limits are changed before drying, adjusted to the feed of the dryer and the properties of the laundry items set. The advantage is the simplicity of the operability of the controller.

An advantageous embodiment of the method according to the invention consists in that the limit values indicate a first and further limit value as well as a maximum temperature of the exhaust air. The advantage is that the controller has the max. Temperature for the end of drying indicates, as temperature alarm TA.

An advantageous embodiment of the method is given by the fact that it is installed on a dryer in the exhaust duct. Advantage is a small footprint. Another advantage: easy retrofitting through the installation of piping equipment and accessories for air conditioning and ventilation.

Another advantageous embodiment of the method is given by the fact that it is installed in front of a dryer as Zuluftinstallation. Advantage is the alternative in the subsequent installation of the process for retrofitting.

An advantageous development of the method as a drying method for commercial laundry drying is given by the method for controlling the heat duty, in which wet items are treated with hot air and the energy requirement with hot air is regulated by the changed over time air requirement by means of a regulation of air volumes, consisting of a pipe guide for transporting the air quantities via a heating stage, a drum for receiving the laundry, a fan for building the induced draft and a pipe for exhaust air,
from parallel piping means with flaps with an integration in the induced draft for the distribution of air volumes, and a temperature sensor for the diagnosis of changes in the exhaust air, in such a way that by means of a guided over the temperature sensor controller the flaps of the pipes are driven by a temperature value,
the temperature value is selected as a limit value for each flap as a limit value and, when individual limit values are reached, the air flow and the energy input are proportionally reduced to the closed pipelines by closing the flap.

Advantage is the simplicity of retrofitting; Another advantage that the convective drying process is installed in addition to an existing hot air generation and switched. The advantage is that the energy task is regulated separately from the altitude. Another advantage is the saving of energy by controlling the convective energy application with hot air and the simplicity of the control with 1 temperature sensor.

Further advantages will be apparent from the attached examples, which are related to 1 to 3 to be discribed.

embodiments

Embodiments are shown as a drawing and are based on the 1 - 3 explained below. In detail show:

1 a control method with a dryer;

2 Control method in the supply air,

3 a temperature diagnosis with exhaust air sensor.

In 1 For the drying of laundry is a temperature-controlled control method for convective drying schematically with the connections to the in the induced draft through the dryer 1 shown guided air flow, which in the present case from the housing 2 of the dryer 1 , a heating stage 3 for heating the air, a rotatable drum 4 for holding wet laundry, a fan 5 to form a suction train from the heating stage 3 over the drum 4 in a continuing pipeline 6 , the pipeline 6 , parallel pipelines 7 . 8th and 9 for splitting the in the pipeline 6 guided airflow and a pipeline 10 for merging the air flow and a regulator 12 , installed in a housing 11 , a power connection 13 to the housing 11 , a temperature sensor 14 to diagnose the actual value and connected to the controller 12 , motorized flaps 15 and 16 , Servomotors 17 and 18 to close the flaps depending on the temperature of the sensor 14 and in the pipelines 7 . 8th , and 9 one volume flow controller each 19 . 20 . 21 is constructed in such a way that at the beginning of drying and reaching the setpoint T7 (T7 means temperature value relative to pipeline 7 ), as shown in the diagram, the engine 17 the flap 15 from the open position to the closed position and the air flow in the parallel pipelines 8th and 9 flows through unchanged, except that the total amount proportional to the amount separated by the closed flap 15 is reduced and that falls below the reference value S (1) in the exhaust air, the relay belonging to the power supply, the flap is reset and the temperature of the exhaust air approaches the target value S (1).

In 1 are tripping functions of the control with a relay shown in the detail A, which consists of a 2 pin power supply 22 and a relay contact 23 exists, which is closed when it reaches the limit and opens when it falls below and by the return spring of the currentless motor the flap 16 goes back to the open normal position. In addition to the described embodiment of the flap control further software-controlled flaps and pneumatically moved flaps for the regulation of the energy task are possible. When carrying out the control, it is important that a partial flow of the convection air is set to zero and that the air flow that has been shut off is switched on again if it falls below the limit, so that the advantages of the method for controlling the energy input in dryers are achieved.

Next, the temperature profile of the control with the temperature T over the time (t) as a graph in 1 shown that from the temperature 39 the heated air and a temperature curve 24 with an increase to the 1st limit ( 1 ), a flat rise between the limit ( 1 ) and the achievement of the limit value ( 2 ) and a further increase to the temperature value ( 3 ) is formed, through which the end of the drying is displayed. Advantage is the saving of energy by the cooling of the heated air on the temperature course 24 by the exhaust-air-controlled control via the temperature sensor 14 is specified as the setpoint. Another advantage: The change of the limits, adjusted to the load and half load with laundry.

Further advantages of the method are in the following 2 described:
In 2 For the drying of laundry, the temperature-controlled control method for convective drying is shown schematically with a connection on the supply side to the dryer 1 shown in the present case starting with the delivery limit 25 from a connection channel 26 to the heating level 3 of the dryer 1 , parallel pipelines 27 . 28 . 29 to give up the split air flow into the connection duct 26 , from the regulator 12 , built into the housing 11 , the power connection 13 to the housing 11 , the temperature sensor 14 connected to the regulator 12 , motorized flaps 30 and 31 with the servomotors 32 and 33 to close the flaps and in the pipes 27 . 28 . 29 one volume flow controller each 34 . 35 . 36 is constructed in such a way that at the beginning of drying and reaching the target value T27 of the engine 32 the flap 30 from the open position by a 90 ° turn and closes the air flow through the open pipes 28 and 29 sucked in unchanged. Next are the parallel pipelines 27 . 28 . 29 each with a volumetric flow controller 34 . 35 . 36 shown. In addition to this representation, one of the volumetric flow controllers could be saved, as long as it is ensured that the relevant pipeline is controlled by the lowest limit value T27 and the partial flows in the open pipelines 28 and 29 be managed.

Next is a throttle point 37 as an aperture in a feed line 38 for primary energy, which, as part of a gas meter or a vapor measurement, allows diagnosis and evaluation of the energy saved, depending on the design of the heating stage as gas firing or as steam heating register.

This in 2 described control method is sufficiently described together with a free intake of room air or outdoor air. The invention further includes the possibility that the partial flows of the air flow by means of the pipes 27 . 28 . 29 are connected to a central line for drying air. As far as the components and the functions with the description in 1 will agree with respect to 1 the same reference numerals and the same function in FIG 2 provided.

The advantage of the representations in 1 and 2 is that the process can be retrofitted depending on the available space and the ventilation piping air supply and exhaust side. Another advantage is that the air flow and the changes in the air flow on the uninstalled side z. B. in the pipeline 6 with pitot tube or over the free cross section before the heating stage 3 can be checked with anemometer.

Further advantages will be given along with the example in 3 described:
In 3 is a temperature diagnosis and documentation of temperatures of a dryer for different laundry items and different load shown, in each of which in diagram I from 10:48 and in diagram II from 11:07 the course of the temperature of the exhaust air over the time axis and for the duration of drying as well as in Diagram I temperatures at 90 ° C over the duration of drying at low load and a very high energy input due to the hot air flow during drying from 10:48 are documented. Furthermore, it can be deduced from the comparison of the temperatures and the steep rise in the temperatures that, starting with the 2nd minute, the high energy requirement can be reduced by closing a flap. Accordingly, a rise in temperature from the 2nd minute through a 2nd threshold below 70 ° C can be avoided. example fuels Steam 8 bar Dryer - drum volume 1 m3 Air volume - measured value 3700 m3 / h at 20 ° C amount 4000 kg / h Hot air max. 1 50 ° C Retrofit - installed: Total airflow 3000 kg / h Distribution on 3 pipes (1000 + 500 + 1500) kg Savings according to diagram I at low load Duration of drying 13 minutes Rated air - 4000 kg 866 kg at 90 ° C in 13 minutes Losses in exhaust air: 866 × 0.24 × 70 14548 kcal Nominal air with control: 2000 kg 466 kg about 80 ° C in 13 minutes Losses in exhaust air: 466 × 0.24 × 60 6710 kcal saving 7838 kcal Savings per hour - 3 fillings: 3 × 7838 23515 kcal Savings in the steam network 23515/860 27.3 kWh Savings on the oil burner - 60% efficiency 27.3 / 0.6 45.5 kWh / h Saving fuel oil: 4.55 liters per hour In the year at 2600 h 11848 liters of fuel oil Saving on CO ₂ 44.9 t CO ₂ / year

The advantage is that the savings in the steam measurement in the supply line after 2 is shown.

LIST OF REFERENCE NUMBERS

1

dryer

2

casing

3

heating stage

4

Drum, rotatable

5

fan

6

pipeline

7

pipeline

8th

pipeline

9

pipeline

10

pipeline

11

casing

12

regulator

13

power connection

14

Temperature sensor, PT 100

15

flap

16

flap

17

engine

18

engine

19

Volume flow controller

20

Volume flow controller

21

Volume flow controller

22

power

23

Relay contact, open / closed for power

24

temperature

25

Delivery limit for connections

26

connecting channel

27

pipeline

28

pipeline

29

pipeline

30

flap

31

flap

32

Motor, servomotor

33

Motor, servomotor

34

Volume flow controller

35

Volume flow controller

36

Volume flow controller

37

restriction

38

Delivery line f. primary energy

39

temperature

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10302973 B3 [0005]
• DE 3903186 A1 [0006]
• DE 102012008193 A1 [0008]
• DE 102012002249 [0009]

Claims (10)

Method for controlling the heat input in tumble dryers, in which wet laundry items are treated with hot air and the energy requirement is regulated with hot air after changing the air demand over time by means of a regulation of air volumes, consisting of a pipe guide for transporting the air volumes via a heating stage 3 , a drum 4 for holding the laundry, a fan 5 for the construction of the induced draft and a pipeline 6 . 8th for exhaust air, from parallel piping means 7 . 8th . 9 ; 27 . 28 . 29 with flaps 15 . 16 ; 30 . 31 with an integration into the induced draft for the distribution of the air quantities, as well as a temperature sensor 14 for the diagnosis of changes in the exhaust air, characterized in that by means of a temperature sensor via the 14 guided regulator 12 the flaps 15 . 16 ; 30 . 31 the piping 7 . 9 ; 27 . 29 ; be controlled by a temperature value, the temperature value as a limit, for each flap 15 . 16 ; 30 . 31 is selected as a limit value and when individual limit values are reached by means of servomotors 17 . 18 ; 32 . 33 ; by closing the flap 15 . 16 ; 30 . 31 the amounts of air and the energy input proportional to the closed pipes 7 . 9 . 27 . 29 be reduced. Method according to the preceding claim 1, characterized in that falls below the limit temperature by the actuating spring containing a return spring 17 . 18 ; 32 . 33 ; by reopening the flap 15 . 16 ; 30 . 31 the amount of air and the energy task are increased. Method according to one of the preceding claims, characterized in that by a volumetric flow controller 19 . 20 . 22 ; 34 . 35 . 36 in the open pipelines the amount of air and the energy input are regulated. Method according to one of the preceding claims, characterized in that when the higher limit value is reached by means of the servomotor comprising a return spring 17 . 18 ; 32 . 33 ; the energy task is regulated in proportion to the amount of air. Method according to one of the preceding claims, characterized in that on control buttons of the controller 12 the limits of the flaps 15 . 16 ; 30 . 31 be set as the setpoint. Method according to one of the preceding claims, characterized in that limits are changed before drying, adjusted to the loading of the dryer and the properties of the laundry items set. Method according to one of the preceding claims, characterized in that the limit values indicate a first and further limit value and a maximum temperature TA at which the drying is stopped. Method according to one of the preceding claims, characterized in that it enters the pipeline 6 is installed for exhaust air. Method according to one of the preceding claims, characterized in that it is installed in front of a dryer as a supply air installation. Drying method with a control of the heat application according to the method of claim 1, in which wet laundry items are treated with hot air and the energy requirement with hot air is controlled by the changed air demand over time by means of a regulation of air volumes, consisting of a pipe guide for transporting the Air volumes via a heating stage, a drum for holding the laundry, a fan for building the induced draft and a pipe for exhaust air, from parallel piping means 7 . 8th . 9 ; 27 . 28 . 29 with flaps 15 . 16 ; 30 . 31 with an integration into the induced draft for the distribution of the air quantities, as well as a temperature sensor 14 for the diagnosis of changes in the exhaust air, characterized in that by means of a temperature sensor via the 14 guided regulator 12 the flaps 15 . 16 ; 30 . 31 the piping 7 . 9 ; 27 . 29 be controlled by a temperature value, the temperature value as a limit, for each flap 15 . 16 ; 30 . 31 is selected as the limit value and when individual limit values are reached by means of servomotors 17 . 18 ; 32 . 33 by closing the flap 15 . 16 ; 30 . 31 the amount of air and the energy input proportional to the sealed pipes 7 . 9 ; 27 . 29 ; is reduced and falls below the limit temperature by the return spring-containing actuator 17 . 18 ; 32 . 33 by reopening the flap 15 . 16 ; 30 . 31 the amount of air and the energy task are increased.

Images