DE102017009465B4 - Facility for processing biomass - Google Patents

Abstract

Device (13) for processing and drying biomass (B) with a fuel dryer (2) which has a dryer drum (3), wherein • the dryer drum (3) has a filling opening (5) for filling and an outlet opening (6) for removal of biomass (B), • a device for moving the biomass (B) along the inner wall of the dryer drum (3) is arranged inside the dryer drum (3), • tempered process air for drying the biomass (B) of the dryer drum (3). (L) is supplied, • the dryer drum (3) is provided with a heater (26) for heating the biomass (B) and • the biomass (B) is simultaneously dried and shredded during operation.

Description

The invention relates to a device for processing and drying biomass.

Biomass: Organic substances of a biogenic, non-fossil type for energy use, for example for use in biomass heating systems.

According to the definition of the Federal Association of Agricultural Professional Associations: biomass heating systems. Kassel, 2008, p. 3, the energy term biomass includes animal and plant products that can be used to generate heating energy, electrical energy and as fuel. The term biomass refers exclusively to animal and plant substances, but not to microbial substances. In addition, within animal and plant materials, it only includes those substances that can be used for energy purposes.

In the context of the invention described, biomass is an energy source made from phytomass and zoomass. This also includes follow-up and by-products, residues and waste resulting from phytomass and zoomass, the energy content of which comes from phytomass and zoomass.

Heat generation from bioenergy is economically interesting, which is promoted in Germany, for example, by the Renewable Energy Heat Act (EEWärmeG). This particularly applies to the use of biomass for pellet heating.

A large amount of biomass occurs on horse farms in the form of horse manure mixed with sawdust and straw. Keeping horses, especially for breeding and as a recreational sport, has become an important, albeit little-noticed, economic factor worldwide, including in Germany. The number of horses and ponies kept for these purposes in Germany alone is estimated at around 1 million animals. The total turnover of this industry in Germany is around €6 billion annually. Approximately 57 m ³ of horse manure is produced per horse per year (approx. 25 kg of fuel per horse per day), including bedding in the form of straw or sawdust. The calorific value of horse manure is interesting and worth noting. By burning 1 kg of horse manure, 3.5 to 4.0 kWh can be obtained. The calorific value of 1 kg of horse manure in a dried form suitable for combustion is roughly comparable to the calorific value of 200 to 300 ml of heating oil.

At manure removal points in stables for pets, such as horses, pet manure or horse manure accumulates as a mixture together with the respective bedding material for the animals, for example straw or sawdust, mixed with leftover feed, such as hay.

Pellets obtained from this are suitable for filling CHP plants (combined heat and power plants), which in turn generate electricity and heat for heating.

An introduction to the basics, techniques and processes in energy production from biomass is in KALTSCHMITT, M; HARTMANN, H, HOFBAUER, H; Energy from biomass. Basics, techniques and procedures. 2nd Edition. Berlin Heidelberg: Springer-Verlag, 2009, pp. 314-332. ISBN 978-3-540-85094-6 can be found. Described for drying the biomass are, among other things, batch or box dryers with controlled recirculation. Such systems are widespread, but they are very voluminous and require complex sealing for recirculation.

A device and method for producing pellets from biomass obtained from horse manure is already available DE 10 2006 006 701 B3 disclosed. A correspondingly suitable heating system and method for operating a heating system, in particular using horse manure, is in the DE 102 26 538 A1 published.

From this, the state of the art developed from the WO 2012/152248 A2 published facility for the processing of biomass. The special highlight here was the idea of cooling process air with a refrigerant in a heat exchanger before it is fed to the fuel dryer, during which moisture is removed from the process air through condensation. However, before the process air is fed to the dryer, it is heated. Process air that has been dried and warmed up in this way would be able to remove the unwanted moisture relatively quickly when it comes into contact with the biomass in the fuel dryer and dry it.

A further step towards a more compact design with controlled recirculation is in the WO 2012/059075 A2 disclosed. There is a dryer drum with an internal rotor for drying and shredding the biomass.

However, the design effort required for controlled recirculation in these two devices described is considerable, since in addition to the components for drying the biomass, the supply and discharge of the process air and the device for pressing the dried biomass into shaped pieces, there is a refrigeration system with an evaporator is to install. In addition, there is the control and regulation effort required to coordinate the refrigeration process parameters with the process steps of drying and conveying the biomass. During the extensive testing it finally became clear that the control and the necessary equipment expenditure are economically unattractive for an operator of such a system.

Proceeding from this, it is the object of the invention to provide a generic device with which the energy and equipment expenditure for processing the biomass is minimized.

According to the invention, the object is achieved by the features mentioned in the independent patent claim, namely patent claim 1.

With regard to the device for processing biomass, according to the features of patent claim 1, the biomass is fed to a fuel dryer in batches and dried by circulating it with process air. After the dried biomass has been removed from the fuel dryer, it is pressed into shaped pieces. The process air continuously flowing through the fuel dryer can be heated upstream of the fuel dryer by means of a heating medium in a heat exchanger; the process air moistened in the fuel dryer is then removed from the fuel dryer. The drying process finally comes to an end when either the biomass in the fuel dryer or the discharged process air has reached a target humidity.

The dryer drum, which is equipped with a heater, significantly accelerates the drying process in the fuel dryer, which means that the biomass is heated immediately and therefore more efficiently.

The particular advantage of this invention is that the device can be used to process the biomass for use in a heating system with a few, simple components and thus the processing process can be reliably controlled with a few control variables. The target humidity of the biomass in the fuel dryer or the discharged process air can be used as a control variable, whereby recording the target humidity of the biomass in the fuel dryer represents a more direct and precise process control. It is expedient to process the process and record and control the relevant process parameters via a programmable control device, such as a commercially available Simatic controller.

This means that important quality parameters of the shaped pieces or pellets to be produced, which are defined by relevant standards, can be maintained or controlled. This particularly concerns the water content for pellets for non-industrial and industrial use. For wood pellets, for example, ISO 17225-2 “Biogenic solid fuels - fuel specifications and classes” applies.

Due to the compact design of the device with its components, it is possible to design the device as mobile system parts that, when loaded or mounted on a vehicle, can be used for service purposes - for example in contracting companies.

In a further development of the invention, the fuel dryer is provided with an additional heater to accelerate the drying process. The heater is partially formed on the lateral surface of the dryer drum and preferably extends over a circumferential angle α of approximately 75° to 225°.

• 1 einen einfachen, schematischen Verfahrensablaufplan für ein erfindungsgemäßes Verfahren zur Aufbereitung von Biomasse,
• 2 einen schematischen Querschnitt durch eine Einrichtung zum Aufbereiten von Biomasse mit Darstellung der Massenströme,
• 3 eine Seitenansicht einer Einrichtung zum Aufbereiten von Biomasse mit Bezeichnung der Komponenten,
• 3a einen Querschnitt A-A gemäß 3 der Einrichtung,
• 4 eine perspektivische Ansicht einer Einrichtung und
• 5 eine schematischer Plan zur Darstellung des Biomassenstromes.

The invention can be better understood by reference to the accompanying 1 until 5 is taken. Show it

• 1 a simple, schematic process flow chart for a process according to the invention for processing biomass,
• 2 a schematic cross section through a device for processing biomass showing the mass flows,
• 3 a side view of a device for processing biomass with names of the components,
• 3a a cross section according to AA 3 the facility,
• 4 a perspective view of a facility and
• 5 a schematic plan to represent the biomass flow.

In 1 a schematic process flow chart for a process for processing biomass B is shown.

To carry out the method, a device 1 for processing biomass B is shown schematically. The device 1 essentially consists of a fuel dryer 2 with a dryer drum 3, which is formed in the manner of a lying hollow cylinder with a horizontally extending axis of rotation 4. The fuel dryer 2 has a closable filling opening 5, which is provided approximately in the middle of the circumference of the dryer drum 3, through which the dryer drum 3 can be charged with biomass B. The filling opening 5 lies above the axis of rotation 4 and extends approximately parallel to it, so that when the fuel dryer 2 is loaded, the biomass B falls under gravity into the center of the dryer drum 3.

Diametrically opposite the filling opening 5, on the lower jacket section, there is a closable outlet opening 6, which extends approximately parallel to the axis of rotation 4. Dried biomass B is removed from the fuel dryer 2 via this outlet opening 6. From there, the dried biomass B can be fed to a storage bunker (not shown) for pelletizing.

At the front end of the dryer drum 3, an air inlet opening 7 is provided, through which the dryer drum 3 is supplied with process air L. A heat exchanger 8 is arranged upstream of the air inlet opening 7, via which the process air L can be tempered by means of a heating medium W. The heat supply in terms of temperature and amount of heat can be controlled via a control device for process control of the device 1. A water circuit (not shown) of an exhaust gas heat exchanger of a heating system serves as the heat medium W. The heating system in turn is heated with the pellets produced by device 1. As a rule, the temperature of the process air L when it enters the fuel dryer 2 is 60 ° C.

At the opposite front end of the dryer drum 3, an exhaust air duct 9 is provided, via which the moistened process air L is removed from the dryer drum 3. For this purpose, a fan 10 is arranged downstream of the air outlet opening 9, which conveys the process air L. The pressure drop that arises in the dryer drum 3 when the fan 10 is in operation suppresses the unwanted escape of dust from the fuel dryer 2.

The fuel dryer 2 is also in the 3 , and 3a carried out in detail.

1. a) Befüllung: der Brennstofftrockner 2 wird manuell oder mechanisch mit einer Charge Biomasse B, die ungetrocknet, einschließlich des enthaltenen Wassers vorliegt, befüllt, wobei die Charge zuvor in ihrer Menge bemessen wird.
2. b) Trocknung: die in dem Brennstofftrockner 2 befindliche Frischbiomasse wird mit vorgewärmter Prozessluft L umgewälzt und auf eine vorbestimmbare Zielfeuchtigkeit (14% oder weniger) abgetrocknet, dabei nimmt die Feuchtigkeit der Prozessluft L während des Trocknungsprozesses und in stromabwärtiger Richtung innerhalb des Brennstofftrockner 2 zu.
3. c) Entleerung: die getrocknete Biomasse B (,Trockenbiomasse') wird über die Austrittsöffnung 6 vom Brennstofftrockner 2 ausgetragen und zur weiteren Verwertung abgefördert.

Using the schematic process flow chart 1 The material flow of the biomass B during the operation of the device 1 can be represented in three successive basic phases a) to c):

1. a) Filling: the fuel dryer 2 is filled manually or mechanically with a batch of biomass B that is undried, including the water it contains, the quantity of the batch being measured beforehand.
2. b) Drying: the fresh biomass located in the fuel dryer 2 is circulated with preheated process air L and dried to a predeterminable target humidity (14% or less), while the moisture of the process air L increases during the drying process and in the downstream direction within the fuel dryer 2.
3. c) Emptying: the dried biomass B ('dry biomass') is discharged from the fuel dryer 2 via the outlet opening 6 and conveyed away for further utilization.

1. A) Erwärmen der aus der Umgebungsluft entstammenden Prozessluft L über einen Wärmetauscher 8 auf ca. 70°C,
2. B) Einleitung der erwärmten Prozessluft L in den Brennstofftrockner 2, wobei die Einleitung während des Trocknungsprozesses zeitweise oder dauernd erfolgt
3. C) Aufnahme des Wasserdampfes aus der Frischbiomasse B, weitere Erwärmung der Frischbiomasse B im Brennstofftrockner 2.
4. D) Die weitgehend gesättigte Prozessluft L verlässt Brennstofftrockner 2 auf der gegenüberliegenden Seite, wobei die Prozessluft L von einem Gebläse 10 gefördert wird.

Likewise, based on the 1 the mass flow of the process air L and its process work during the operation of the device 1 are represented in the following four basic phases A) to D):

1. A) heating the process air L from the ambient air to approx. 70 ° C via a heat exchanger 8,
2. B) Introduction of the heated process air L into the fuel dryer 2, the introduction occurring temporarily or continuously during the drying process
3. C) Absorption of the water vapor from the fresh biomass B, further heating of the fresh biomass B in the fuel dryer 2.
4. D) The largely saturated process air L leaves fuel dryer 2 on the opposite side, with the process air L being conveyed by a fan 10.

The mass flow of the process air L and the material flow of the biomass B are controlled via a control unit (not shown) during the operation of the device 1, so that after the fuel dryer 2 has been filled with a batch of biomass B, the drying process is carried out in an automatically controlled manner.

• Im Inneren der Trocknertrommel 3 ist ein koaxial angeordneter Rotor 11 installiert, der mit Greifarme 12 versehen ist, die über seinen Umfang und axial verteilt angeordnet sind. Der mit einem Drehantrieb 13 gekuppelte Rotor 11 wälzt mit die in der Trocknertrommel 3 befindliche Biomasse B während des Betriebes um und bringt diese in Kontakt mit der die Trocknertrommel 3 durchströmenden Prozessluft L. Dabei wirken die radial sich erstreckenden Greifarme 12 mechanisch auf die Biomasse B ein und zerkleinern diese. Während des Betriebes ist die Drehrichtung des Rotors 11, rechts- oder linksdrehend umstellbar.

2 shows the facility 1 compared to the in 1 Device 1 shown in a higher level of detail with additional components. In addition to the in 1 Components shown is in 2 the following shown:

• Inside the dryer drum 3, a coaxially arranged rotor 11 is installed, which is provided with gripping arms 12 which are arranged axially distributed over its circumference. The rotor 11, coupled to a rotary drive 13, circulates the biomass B located in the dryer drum 3 during operation and brings it into contact with the process air L flowing through the dryer drum 3. The radially extending gripper arms 12 act mechanically on the biomass B and chop them up. During operation, the direction of rotation of the rotor 11 can be changed to clockwise or counterclockwise.

Above the filling opening 5, a filling funnel 22 is formed, via which the fuel dryer 2 is fed with bulk-like biomass B. The filling opening 5 can be closed with a slide 14, so that the fuel dryer 2 remains closed during the drying process and during operation of the rotor 11. This is a safety aspect to prevent people or objects from accidentally getting into the dryer drum 3. In addition, the slider 14 has a dust seal 24, which prevents undesirable dust contamination of the environment.

At the downstream, front end of the dryer drum 3, the exhaust air duct 9 is connected to it, via which the warmed and moist process air L is removed from the dryer drum 3 and discharged to the outside. The mass flow of the process air L is controlled via a fan 10 which is arranged in the exhaust air duct 9 and can be controlled via the control unit. The particles picked up in the process air L, such as dust, etc., are separated via a separator located further downstream and fed to the fuel dryer 2 for utilization. The process air L cleaned in this way is then released into the open air, whereby a residual dust quantity of max. 20 mg/m ³ is achieved.

Opposite the to the 1 and 2 The device 1 described is the device 1 according to 3 supplemented by further functional components.

After the biomass B has been dried to a target moisture content of a maximum of 14% that can be specified via the control unit and the long-fiber portions have been comminuted in the dryer drum 3, pelletizing takes place in a further process step. This process step makes the biomass B easier to handle for continuous feeding of a heating system. In addition, pelleted biomass B can be stored very well without significantly changing its physicochemical properties. The pellets can be temporarily stored in short-term or long-term storage facilities such as silos 16. They can also be easily transported as pellets due to their shape, which is convenient for handling with an automatic conveyor. A screw conveyor or a chain conveyor or a conveyor belt can be provided to remove the pellets from the silo and feed them to a burner of a heating device.

The waste heat generated in a heating device can be used in two ways, for example. On the one hand, a hot water circuit can be operated for a residential or commercial building or the like in the area of stables.

On the other hand, hot water can be made available for the buildings. A heat exchanger 8 can also be operated with the heating device in such a way that with the help of the heat dew shear 8 the process air L is heated for dehumidification and drying of the biomass B and a high saturation deficit is achieved.

To pelletize the biomass B, as in 3 shown, a commercially available pelletizer 17 is added to the device 1. The dried biomass B removed from the fuel dryer 2 via the outlet opening 6 is conveyed to a buffer 19 via a screw conveyor 18. From there, the biomass B reaches the pelletizer 17 for pressing the shaped pieces. The finished pressed pellets then reach the silo 16 via another conveyor 20.

The 3a shows a cross section according to AA 3 the facility 1.

The dryer drum 3 of the fuel dryer 2 can be seen in the center of the cross section AA. Its longitudinal axis also forms the axis of rotation 4 of the rotor 11, which is mounted coaxially inside the dryer drum 3. The axis of rotation 4 extends perpendicular to the plane of the cross section AA. As the direction of rotation arrow shows, the rotor 11 rotates counterclockwise during operation.

Furthermore, the cross section AA within the dryer drum 3 is divided into four quadrants I, II, III and IV to facilitate further reference with center Z lying on the axis of rotation 4, with quadrant I at the top right, quadrant II at the bottom right, quadrant III at the bottom left and quadrant IV is at the top left.

In the area of quadrant IV, the filling opening 5 is formed on the circumference of the dryer drum 3, via which the dryer drum 3 is fed with biomass B. In the area of quadrant III, the outlet opening 6, which can be closed via a flap 23, is designed on the circumference of the dryer drum 3, via which dried biomass B is conveyed out of the dryer drum 3. Both filling opening 5 and outlet opening 6 have, as in 3 can be seen, in addition to the expansion in the circumferential direction, there is also an expansion in the axial direction of the dryer drum 3.

The design of the outlet opening 6, which is laterally offset with respect to the center Z, benefits when emptying the dryer drum 3. Due to the left-handed rotor 11 in the example, the biomass B is moved along the inner wall of the dryer drum 3 over the areas of the quadrants in the order of the circumferential direction III-II-I, raised and finally falls to the left of the rotor 11, in the area of quadrant III Bottom of the dryer drum 3 down, where the initially closed outlet opening 6 is located. The laterally offset design of the outlet opening 6 thus makes it considerably easier to empty the dryer drum 3 with as little residue as possible and also reduces the overall height of the fuel dryer 2. By reversing the direction of rotation of the rotor 11 once or several times, a largely complete emptying via the opened outlet opening 6 is made possible.

To accelerate the drying process, the fuel dryer 2 is provided with an additional heater 26, whereby the biomass B is heated directly and therefore more efficiently. The heater 26 partially contacts the inner wall of the dryer drum 3 in the area of quadrants I, II and III over a circumferential angle α of approximately 150 °. The heater 26 is formed by meandering pipes, not shown, which are connected to a hot water heater. In the longitudinal direction, the heater 26 extends just over the effective inner length of the dryer drum 3.

The heater 26 thus predominantly heats the lower right inside of the dryer drum 3 so that when the rotor 11 is operated counterclockwise, the biomass B is moved by the gripping arms 12 over the areas of the quadrants in the order of the circumferential direction III-II-I. The biomass B passes over the heated inside and is thus heated up. In the area of quadrants I and IV, the biomass B falls from the inner surface down into the area of quadrants II and III, from where the biomass B is heated again along the heated inner wall until the drying process is completed. Heating in the area of quadrant IV is not necessary and is therefore unnecessary, especially since there is practically no contact between the biomass B and the inner wall there.

By designing the heater 26 in the area of the inner wall of the dryer drum 3 coated with the biomass B, the biomass B present as bulk material is moved by the rotor 11 along the heated inner wall. What is important here is that the heater 26 is designed in the area of the gripper arms 12 that rise during operation of the rotor 11, since there the biomass B is conveyed upwards by the gripper arms 12 on the inner wall. The heat transfer from the heated inner wall to biomass B is therefore immediate and optimal.

Six radially extending gripping arms 12 are attached to the rotor 11 at the same angular distance and extend radially to the inner wall of the dryer drum 3 and form a small gap of a few mm with it. The gap is large enough to compensate for different, operational expansions between the gripper arms 12 and the dryer drum 3 without the gripper arms 12 touching the inner wall during operation. At the same time, the gap is small enough that the biomass B can be completely gripped and circulated without biomass being deposited on the inner wall of the dryer drum 3. At the drum-side end of the gripper arms 12, plate-shaped grippers 21 are attached, which convey the biomass B from the bottom of the dryer drum 3, throw it up and bring it into the stream of process air L. The biomass B is shredded and dried by circulating it with the process air L.

In 4 shows the device 1 in a perspective view. The fuel dryer 2 is provided with thermal insulation 26 on the outer circumference of the dryer drum 3 in order to avoid heat losses during operation of the fuel dryer 2 and to optimize the efficiency of the device. In addition, the expansion of the heater 26 attached to a partial lateral surface of the dryer drum 3 can be seen in the longitudinal and circumferential directions.

1. a) Separierung der rohen, unbehandelten Biomasse B in deren Bestandteile Dung und Einstreu, Zuführen des Dungs zum Brennstofftrockner 2, Weiterverarbeitung des Dungs als Dünger,
2. b) Separierung der rohen, unbehandelten Biomasse B in deren Bestandteile Dung und Einstreu, Zuführen des Einstreus zum Brennstofftrockner 2, Weiterverarbeitung des Einstreus als Brennstoff oder
3. c) Zuführen der unbehandelten Biomasse B zum Brennstofftrockner 2, Weiterverarbeitung der Biomasse B als Brennstoff.

The schematic process diagram below 3 illustrates the separation of biomass B before it enters the fuel dryer 2. Using the example of biomass B coming from stables, there are generally three types of operation for processing biomass B:

1. a) Separating the raw, untreated biomass B into its components, manure and litter, feeding the manure to the fuel dryer 2, further processing the manure as fertilizer,
2. b) Separating the raw, untreated biomass B into its components, manure and litter, feeding the litter to the fuel dryer 2, further processing the litter as fuel or
3. c) feeding the untreated biomass B to the fuel dryer 2, further processing the biomass B as fuel.

Production parameters from the test operation of facility 1 are explained below. In a first drying cycle, a batch with 165 kg of biomass B with a water content of originally 42% was reduced to 13%. 55kg of water were removed from the batch over a period of 8h13min. The resulting energy balance is shown in the table below: Energy balance (165 kg with 42% to 13%) Oil price 0.6 € amount of heat used 7.03 kWh Calorific value of 1 liter of oil 10.00 kWh theoretical oil consumption 0.70 I theoretical cost of oil 0.42 € corresponds to wood briquette at F. 2.5 1.75 kg Power consumption 10.19 kWh Electricity costs €0.20/kWh 2.04 € Total cost of energy 2.46 € Total weight after drying 110.00 kg excess 25.98 € Surplus converted into oil 43.30 1 theoretical annual surplus 9482.70 €

In a second drying cycle, a batch with 228 kg of biomass B with a water content of originally 54% was reduced to 18%. 100 kg of water were removed from the batch over a period of 11 hours and 25 minutes. The resulting energy balance is shown in the table below: Energy balance (228 kg with 54% to 18%) Oil price 0.6 € amount of heat used 9.74 kWh Calorific value of 1 liter of oil 10.00 kWh theoretical oil consumption 1.00 1 theoretical cost of oil 0.60 € corresponds to wood briquette at F. 2.5 2.50 kg Power consumption 17.00 kWh Electricity costs €0.20/kWh 3.40 € Total cost of energy 4.00 € Total weight after drying 127.80 kg excess 30.07 € Surplus converted into oil 50.12 I theoretical annual surplus 10975.55 €

Reference symbol list

1

Furnishings

2

Fuel dryer

3

Dryer drum

4

Axis of rotation

5

Filling opening

6

Exit opening

7

Air inlet opening

8th

Heat exchanger

9

exhaust duct

10

fan

11

rotor

12

Gripping arms

13

Rotary drive

14

Slider

15

separator

16

silo

17

Pelletizer

18

Auger

19

Cache

20

funding

21

Grabber

22

Filling funnel

23

flap

24

Dust seal

25

Rotary drive

26

Heating

27

Thermal insulation

b

Biomass

L

Process air

W

heat medium

Z

center

Claims (6)

Device (13) for processing and drying biomass (B) with a fuel dryer (2) which has a dryer drum (3), wherein • the dryer drum (3) has a filling opening (5) for filling and an outlet opening (6) for removing biomass (B), • a device for moving the biomass (B) along the inner wall of the dryer drum (3) is arranged inside the dryer drum (3), • tempered process air (L) is supplied to the dryer drum (3) to dry the biomass (B), • the dryer drum (3) is provided with a heater (26) for heating the biomass (B) and • During operation, the biomass (B) is dried and shredded at the same time. Setup after Claim 1 characterized in that the device for moving and shredding the biomass (B) has a rotor (23) with grippers (24) and a rotary drive (25) for rotating the rotor (23). Setup according to one of the Claims 1 until 2 , characterized in that the device for moving and shredding the biomass (B) has a rotor (23) which is arranged coaxially within the dryer drum (3). Setup according to one of the Claims 1 until 3 , characterized in that the heating of the fuel dryer (2) is operated via a heating medium or electrically. Setup according to one of the Claims 1 until 4 , characterized in that the heating is carried out over part of the surface of the jacket of the dryer drum 3 along a peripheral section. Setup according to one of the Claims 1 until 5 , characterized in that a cross section of the cylindrical dryer drum 3 in the circumferential direction (UR) describes quadrants I, II, III and IV and wherein the heater (26) is at least partially on the jacket of the dryer drum 3 at least in the area of quadrants I and II or IV and III is trained.

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