EP1551533A1

EP1551533A1 - Device and method for drying a gas flow

Info

Publication number: EP1551533A1
Application number: EP03765031A
Authority: EP
Inventors: Michael Zlotos
Original assignee: Mann and Hummel GmbH
Current assignee: Protec Polymer Processing GmbH
Priority date: 2002-07-20
Filing date: 2003-07-17
Publication date: 2005-07-13
Also published as: DE10233015A1; WO2004009218A1

Abstract

The invention relates to a method and a device for drying a gas flow, in particular for a bulk material dryer. Said device comprises at least two desiccant wells (20, 21), temperature sensors (27, 28), guide elements (29, 30) and gas conduction conduits (17). According to the invention, each desiccant well (20, 21) has one inlet (25), one outlet (26), one heating device (22, 23) and one desiccant (24), whereby the latter (24) is located between the inlet (25) and the outlet (26). The heating device (22, 23) is designed to heat the gas flow, the temperature sensors (27, 28) are provided for detecting the temperature of the gas flow, the guide element (29, 30) is provided for guiding the gas flow and the gas conduction conduits (17) are connected to the desiccant wells (20, 21) by means of a circuit. The device is provided with a single fan (19), which is connected to the desiccant wells (20, 21) by means of the circuit. The guide element (29, 30) is located downstream of the desiccant wells (20, 21) in the gas flow direction and the guide element (29, 30) is connected to the temperature sensors (27, 28) by means of the circuit.

Description

Device and method for drying a gas stream

description

State of the art

The invention relates to a device for drying a gas stream, preferably in a bulk material dryer, in particular a two-chamber dryer, according to the preamble of claim 1. The invention also relates to a method for drying a gas stream according to the preamble of claim 7.

EP 0 884 085 A1 describes a method and a device for the regeneration of a moisture-adsorbing medium. There is a fan here, which ensures the circulation of the air flow to dehumidify the air and dehumidify the desiccant. The air flow is controlled by an arrangement of four valves arranged in front of the desiccant pots in the gas flow direction. With the help of this arrangement, part of the dried air can be used to dehumidify the desiccant pot to be regenerated. In one embodiment of the device, use of the ambient air is possible for this purpose, for this purpose two additional valves are integrated into the outlet lines of the desiccant pots. The desiccant heated during dehumidification, in each case via a heater arranged in the desiccant pot, is cooled by means of ambient air in each case via an additional fan which is arranged in each desiccant pot. The opening and closing of the valves is controlled by a logic controller, which processes moisture, temperature or time signals.

The invention has for its object to provide a device and a method for drying a gas stream, which is inexpensive, simple in construction and has a low energy consumption.

This object is achieved according to the invention by the features of claims 1 or 7. Furthermore, the subclaims indicate appropriate further developments. Advantages of the invention

The device according to the invention and the method according to the invention are preferably used in bulk dryers. However, there are other types of use, such as Dehumidifier or the like is conceivable.

The device according to the invention has at least two desiccant pots, furthermore steering means, gas guide channels and a single blower. The gas to be dried is sucked in via the blower and passed through the gas guide channels to a respective inlet of the desiccant pots. The gas routing channels preferably have the same channel length and preferably the same channel diameter, the basic shape of the gas routing channels being round, angular or as desired. With a preferably identical design with regard to throughput, volume and size of the desiccant pots, the gas guide channels to the individual desiccant pots should preferably have the same internal volume with the same pressure loss between the blower and the inlet of the desiccant pots. The desiccant pots each have a heating device, a desiccant and an outlet, the desiccant being arranged between the inlet and the outlet. The heating device can be a heating coil, a radiator or another means known in the prior art for achieving switched heating, and is used to selectively heat either the gas stream flowing through the drying agent or the drying agent itself. By means of this heating, the desiccant saturated with moisture is regenerated by releasing the adsorbed moisture into the flowing gas stream. The desiccant is preferably molecular sieve, but can also be any other means known in the art for adsorbing moisture from a gas stream. The moisture of the gas stream to be dried is taken up in the desiccant which is not yet saturated with moisture from the moist gas flowing through. Then, in the flow direction after the desiccant pots, steering means are provided in the gas guide channels, which guide the respective gas flows. These steering means can be designed as valves, flaps or other means known in the prior art for influencing a fluid flow. The steering means are preferably designed as a 4-way valve and as a throttle valve, the 4-way valve being arranged in the junction of the two gas guide channels led out of the desiccant pots, the third way opening into a further gas guide channel and the fourth way in a gas guide channel which with the environment is bound, flows. In the preferred embodiment of the steering means, a throttle valve, which can open and close this path, is arranged in the gas guide channel connected to the surroundings. However, other arrangements and designs of the steering means can also be envisaged, in which, for example, the steering means are arranged individually in the respective gas routing channels led out of the desiccant pots. A timing of the steering means ensures that this device realizes gas routing for gas dehumidification and complete regeneration of the desiccant with only a single fan. The low cost of materials combined with the low energy input of this device compared to the prior art is particularly advantageous here. There are fewer moving parts in the device and this logically results in a longer life of the device.

An advantageous embodiment of the device can be seen in the fact that a temperature sensor is provided for detecting the temperature of the gas streams flowing out of the desiccant pots through the gas guide channels. This single temperature sensor is preferably arranged in the gas guide channel connected to the environment after the two gas guide channels leading out of the desiccant pots have been brought together. The temperature sensor can also be arranged at further positions of the gas duct, it only has to be ensured that the temperature of the gas stream leaving the respectively regenerating desiccant pot is detected. The steering means are correspondingly connected to the temperature sensor, which connection can be mechanical, electrical or electronic in nature. This stipulates that the temperatures detected by the temperature sensor have an influence on the position of the steering means. It is thereby achieved that this device realizes gas routing for gas dehumidification and complete regeneration of the drying agent with only a single blower and this gas routing is realized by the steering means depending on the temperatures prevailing in the respective gas streams.

In a further advantageous embodiment of the device, at least two temperature sensors are provided in the flow direction after the respective outlet of the desiccant pots for detecting the temperature of the outflowing gas. These temperature sensors can be designed electrically, electronically or mechanically analogous to the above temperature sensor. As described above, the steering means are correspondingly connected to the temperature sensors, which connection can be mechanical, electrical or electronic in nature. According to a further embodiment of the invention, the heating devices of the desiccant pots can be controlled as a function of the temperatures of the gases flowing out of the desiccant pots and the position of the steering means, determined by means of the temperature sensors. The heating devices are preferably switched on or off in such a way that reaching a predetermined temperature in the gas flow or an end stop of a steering means causes the heating devices to be switched on or off, the heating devices of the various desiccant pots not being switched on at any time. There would also be the possibility that only a combination of a certain gas temperature with a predetermined position of the steering means would lead to a switching of the heating device. In this way, various possible combinations of this configuration can be remembered.

In a further advantageous embodiment of the invention, the heating device of the desiccant pots, the temperature sensors and the steering means are correspondingly connected to one another via a control device. This control device is preferably designed as an electronic microprocessor, which evaluates the incoming signals by means of stored algorithms and reacts with outgoing control signals. Furthermore, the incoming and outgoing values could be visualized directly or indirectly via a display and thus allow conclusions to be drawn about the respective process status of the device and the method, in which case error messages could also be output. This corresponding connection does not necessarily have to be realized via an electronic microprocessor, however, a mechanical connection or a simple electrical switching connection could also be used. Here, too, circuits triggered by input signals can be implemented using simple structural designs. A further modification of the invention has a further heater for heating the gas flow, the heating power of this heater and / or the blower power of the blower being changeable by means of the control device described above. The heating power is preferably adapted accordingly to the temperature prevailing in the gas stream, in order, for example, in the presence of an already heated gas flow, to reduce the heating power and thus save energy. The blower output could also be adapted to the desired gas volume flow.

In the method according to the invention, a gas stream which is caused to flow by a single fan and contains moisture through gas guide channels, which preferably have no influence on the respective volume flows, is split up into two partial streams. divides, these two partial streams being fed via an inlet into desiccant pots. In a first desiccant pot, a partial stream is passed through a desiccant arranged in the desiccant pot, where the moisture of the gas stream is adsorbed, and the dried gas stream then leaves the first desiccant pot via an outlet. In a second desiccant pot, the second partial flow is preferably used at times at the same time as regeneration gas for the regeneration of the desiccant saturated with moisture in this desiccant pot. Regeneration consists of dehumidifying the desiccant and then cooling the desiccant. This means that the regeneration gas is preferably also used to cool the drying agent. The temperature of the desiccant should be low enough after the completion of the regeneration to be used again for the dehumidification of the gas. In practical use, this means a desiccant temperature of less than 100 ° C. The temperature of the regeneration gas is measured with the help of temperature sensors after leaving the second desiccant pot. The control of the gas flow and the regeneration gas takes place via steering means arranged in further gas guidance channels in the flow direction after the desiccant pots, whereby the volume distribution of the partial flows is also realized by the steering means. This control can also include regulation. After completion of the regeneration, a changed gas flow guidance takes place via the steering means, and thereby a changed use of the desiccant pots, so that the desiccant pot previously used for dehumidifying the gas flow is regenerated and the previously regenerated desiccant pot is now used for dehumidifying the gas flow. The advantage resulting from this method lies in the skillful use and control of the gas stream, provided by only one fan, for dehumidifying the gas stream in a first desiccant pot, for temporarily dehumidifying the desiccant in a second desiccant pot and for subsequent cooling of the desiccant of this second desiccant pot. Maximum success is achieved with a low use of materials and energy.

In an advantageous implementation of the method, the steering means are controlled as a function of the temperatures detected by the temperature sensors and, in addition, specifically specified periods of time, it being possible for a controller to also include a regulation. It is preferably provided that the steering means close the flow path through the regenerated desiccant pot when a suitable temperature of well below 100 ° C. is reached in the regeneration gas stream and after a Change the current function of the individual desiccant pots from regeneration to gas dehumidification and vice versa over a period of approximately one hour by changing the gas flows. The specified switching temperature and the specified period of time can of course differ depending on the type and amount of desiccant used and the specific properties of the gas to be dried and must be adapted to the actual circumstances.

Furthermore, an advantageous embodiment of the method consists in that a heating device is provided for each desiccant pot, and these heating devices are controlled as a function of the temperatures of the regeneration gas flow detected by the temperature sensors and the position of the steering means. The heating devices serve to heat the desiccant, either directly or via the gas flowing through, this heating releasing the moisture adsorbed in the desiccant. The desiccant and the gas stream flowing into the desiccant are heated to approx. 200-260 ° C. As the regeneration always takes place alternating with the absorption of moisture and a desiccant pot is constantly used to extract moisture from the gas flow, the heating devices should never be in operation at the same time. This option can be kept open for maintenance purposes, but this is not normally the case. One of the heating devices is preferably switched on as soon as the position of the steering means releases the flow of a partial gas flow through the desiccant pot into the environment. This can be done properly via z. B. Detect limit switches in the steering means. Then then increases the temperature of the regeneration gas flow, which is detected by the temperature sensor after the desiccant pots, to a value between 100 ° C and 160 ° C, the heating device is switched off again.

A further advantageous embodiment of the method consists in that when the temperature falls below a predetermined temperature, the steering means close the flow path through the regenerated desiccant pot and the entire gas flow is directed through the desiccant pot, which dehumidifies the gas stream. As soon as a temperature in the regeneration gas stream of approximately below 100 ° C. is reached, the regeneration of the desiccant is completed to the extent that no further cooling by the gas stream is necessary. In the course of the time in which the regenerated desiccant pot is not flowed through, the desiccant is cooled further automatically by radiation to the surroundings. Experience has shown that the desiccant is again completely free of moisture below temperatures of approx. 50 ° C - 80 ° C usable from gas flows. But here, too, the temperature values depend on the material of the desiccant or on changed times.

In a further embodiment of the method, the steering means direct the gas flow in such a way that part of the heat used in the regeneration, which is in the desiccant after the dehumidification of the desiccant has been completed, is used to heat the gas flow. In some applications, it is necessary to heat the dried gas stream using a further heating device. Part of the heat already used to dehumidify the desiccant is advantageously used for this purpose. This means energy savings through the possibility of lowering the temperature of the additional heating device. The gas stream flowing through the heated desiccant pot for cooling is not directed to the environment by means of the steering means but is fed to the dried partial gas stream and thus ensures a temperature increase in the overall gas stream. Accordingly, the temperature increase obtained in this way does not have to be applied via the additional heating device.

These and other features of preferred developments of the invention are evident from the claims and also from the description and the drawing, the individual features being implemented individually or in groups in the form of subcombinations in the embodiment of the invention and in other areas, and can represent advantageous and protectable versions for which protection is claimed here.

drawing

The invention is described below in the drawing using schematic exemplary embodiments. Here shows

Figure 1 Schematic representation of a two-chamber dryer in a preferred embodiment with two temperature sensors

Figure 2 Schematic representation of a two-chamber dryer in a further embodiment with only one temperature sensor

Figure 3 Schematic representation of a two-chamber dryer to illustrate the process steps with changed flow conditions Figure 4 Schematic representation of a two-chamber dryer to illustrate the process steps with a completely closed gas routing

Figure 5 Schematic representation of a two-chamber dryer to illustrate the process steps after changing the process

Description of the embodiments

1 shows the embodiment according to the invention of a two-chamber dryer 10 with a bulk container 11, which has a container inlet 12 and a container outlet 13 for guiding the gas stream flowing through. The bulk material is preferably formed here by granules 15. Furthermore, a container lid 14 and a granulate inlet 16 are provided for introducing the granulate 15. The dried gas stream enters via the container inlet 12, flows through the granulate 15 preferably from bottom to top, absorbs moisture from the granulate 15 and leaves the bulk material container 11 with the absorbed moisture via the container outlet 13. The container lid 14 or the granulate inlet 16 offer the possibility of pressure compensation against the occurrence of a negative pressure in the bulk material container 11 by a possibility to let in ambient air. The moisture-enriched gas is then passed through gas filter channels 17 through a filter 18 in order to filter out fine particles which may have come from the granulate 15 and contaminate the gas from the gas stream. This filter 18 can be designed as a dry or as a liquid filter, it only has to be able to filter out the fine particles to be expected from the gas stream. Following the filter 18, the gas stream is fed to a blower 19. This blower 19 produces the pressure difference necessary for establishing a gas circulation. At the same time, it ensures gas circulation for dehumidifying the gas flow and also for producing a gas flow for regeneration. The gas stream pressed out of the blower is divided via a fork in the gas guide channels 17, a first partial gas stream leading to a first desiccant pot (A) 20, with a heating device (A) 22 assigned to this desiccant pot (A) 20, an inlet 25, an outlet 26 and a desiccant 24 disposed between inlet 25 and outlet 26. A second partial gas stream is passed to a second desiccant pot (B) 21, with a heating device (B) 23 assigned to this desiccant pot (B) 21, an inlet 25, an outlet 26 and a desiccant 24 arranged between inlet 25 and outlet 26. The partial gas streams passed through the desiccant pots 20, 21 are guided by gas guide channels connected to the respective outlets 26. channels 17 in a first steering means (A) 29, preferably a 4-way valve. In the gas routing channels 17, temperature sensors (temperature sensors (A) 27 and temperature sensors (B) 28) are assigned to the first desiccant pot (A) 20 and the second desiccant pot (B) 21, which are used to record 5 the temperatures of the desiccant pots 20, 21 leaving partial gas flows are provided. The steering means (A) 29 is flowed through by the two partial gas flows via the gas guide channels 17 and has the possibility of combining the gas flows in one or two further gas guide channels 17 or passing them on individually. Here, one of these further gas routing ducts leads via a further steering means (B) 30, before

10 is designed as a throttle valve, into the environment and the second through a further heating device (C) 31 back to the container inlet 12 of the bulk material container 11. In a preferred development, the steering means 29, 30, the heating devices 22, 23, 31, the temperature sensors 27 , 28 and the blower 19 are connected to one another via a control device 33 by data lines 32. The gas flow and the gas flow

15 direction is indicated by arrows in figures one to five. In Fig. 1, the steering means 29, 30 and the heating devices 22, 23, 31 are switched so that the gas flow driven by the blower 19 is divided into approximately equal parts, with dehumidification of the one partial gas flow taking place in the desiccant pot (A) 20 , the dehumidified gas is passed to the fully switched on heater (C) 31 and

20 heated to the dehumidification of the granules 15 is passed through the bulk container 11. The second partial gas stream is heated in the desiccant pot (B) 21 by the heating device (B) 23 and passed through the desiccant 24 saturated with moisture to regenerate the desiccant 24. Here, the moisture stored in the desiccant 24 is evaporated by the heated gas and thus the desiccant

Taken from 25 24. In the further course, the partial gas flow, which is now enriched with moisture, is directed via the steering means (A) 29 to the steering means (B) 30 which is in the open position and from there to the surroundings. The temperature of the regeneration gas stream, i.e. the partial gas stream which is used for drying agent regeneration, is recorded via the temperature sensor (B) and via the data lines.

30 gen 32 passed on to the control device 33. The position of the steering means 29, 30 is also transmitted to the control device 33. The section of the dehumidification process shown in FIG. 1 thus shows the simultaneous dehumidification of the granules 15 via a gas stream with subsequent dehumidification of part of this gas stream and part of the regeneration of the drying agent 24

35 by dehumidifying the desiccant 24 by means of a heated partial gas flow and then removing the moisture to the surroundings. The realization takes place by using a single blower 19 and the corresponding effect of the temperature sensors 27, 28, the heating devices 22, 23, 31 and the steering means 29, 30, these parts of the device in the embodiment shown being connected to the control device 33 via data lines 32 and it comes to the gas flow described above.

FIG. 2 shows an embodiment of the device according to the invention, with only a single temperature sensor 27, 28 being provided for detecting the regeneration gas temperature. 1 corresponding components are provided with the same reference numerals. This is arranged in the section of the gas guide duct 17 which is located between the steering means (A) 29 and the steering means (B) 30. The corresponding position of the steering means 29, 30 ensures that the temperature of the partial gas stream dehumidifying the desiccant 24 is always detected. The gas routing and the arrangement and function of the other components of the device is carried out as in FIG. 1.

FIG. 3 shows the gas dehumidification process, which is continued over time, with component positions changed with reference to FIG. 1. 1 corresponding components are provided with the same reference numerals. As soon as the temperature of the regeneration gas flow detected by the temperature sensor (B) 28 has exceeded a predetermined temperature, preferably between approximately 100 ° C. and 160 ° C., the gas routing channel 17, which is connected to the surroundings, becomes 30 via the steering means (B) 30 closed and the steering means (A) releases the regeneration gas flowing out of the desiccant pot (B) 21 to the dehumidified gas flowing out of the desiccant pot (A) 20. As a result, this common gas stream is heated and the thermal energy to be introduced into the gas stream flowing through the bulk material container 11 can be reduced via the additional heating device (A). This can e.g. B. via the control device 33. Furthermore, when the predetermined temperature limit value of the regeneration gas flow of approximately 130 ° C. is reached, the heating device (B) 23 is switched off. At the beginning of the dehumidification of the drying agent 24, the partial gas stream flowing through the drying agent pot (B) 21 is heated to a temperature of approximately 200 to 260 ° C. by means of the heating device before the drying agent 24 flows through it. When the drying agent 24 flows through, a large part of the heat stored in the gas stream is converted into the enthalpy of vaporization of the moisture stored in the drying agent 24. The vaporized moisture is then carried away by the gas stream as it passes through the desiccant 24. The temperature measured by the temperature sensor (B) 28 downstream of the desiccant pot (B) 21 remains constant. meanwhile roughly constant. As soon as the moisture stored in the drying agent 24 has been almost completely evaporated, the temperature of the gas stream leaving the drying agent rises further. A recorded temperature between 100 ° C and 160 ° C, depending on material constants, location of the measuring point, etc., indicates an almost complete evaporation. In addition, there should be a certain degree of security against the temperature fluctuation occurring in the evaporation process, and that there is an unnecessary expenditure of energy due to the heating up of the gas flow for too long. The small proportion of residual moisture in the desiccant 24 after the heating device (B) 23 is switched off is evaporated by the heat still stored in the desiccant 24. In the further course, the no longer heated partial gas stream flowing through the desiccant pot (B) 21 cools the through-flow desiccant 24, so that the heat absorbed in the further course of the gas flow, by the above-described change in the position of the steering means 29, 30, for heating the total gas flow is used. The temperature value between 100 ° C and 160 ° C is a value chosen from experience, which allows sufficient security. However, depending on the desiccant 24, its volume or the position of the temperature sensors 27, 28, temperatures deviating from this value can be used as the switching temperature.

FIG. 4 shows the gas dehumidification process, which is continued over time, with the component positions changed with reference to FIG. 3. 1 corresponding components are provided with the same reference numerals. As soon as the regeneration gas flow temperature detected by the temperature sensor (B) 28 falls below a value of approximately 100 ° C., the connection to the dehumidified gas flow, which flows through the desiccant pot (A) 20, is closed via the steering means (A) 29. Since the connection to the environment is still closed by the steering means (B) 30, the entire gas flow made available by the blower 19 flows through the desiccant pot (A) 20 for dehumidification Heating power of the additional heating device (C) 31 increased again, since the additional heat is eliminated from the regeneration gas stream. The regeneration of the desiccant 24 in the desiccant pot (B) 21 has now been completed. Experience has shown that the desiccant 24 is again fully absorbable for moisture below a temperature of approximately 100 ° C. Furthermore, after the flow path has been closed, there is an additional cooling of the desiccant 24 by heat radiation to the environment. The cooling depends on the ambient temperature and the further cooling time allowed. The initial temperature of well below 100 ° C is based on experience, but depending on the desiccant 24 used, the amount of dry The corner means 24 or the position of the temperature sensors 27, 28 vary. Likewise, the condition of the drying means 24 could also be determined by means of moisture sensors which either detect the moisture of the gas flowing through or directly sense the moisture of the drying agent. A corresponding connection to the control device 31 could then be used to switch the components influencing the flow and the dehumidification on the basis of the detected moisture values.

FIG. 5 shows the gas dehumidification process, which is continued over time, with the component positions changed with reference to FIG. 4. 1 corresponding components are provided with the same reference numerals. After a predetermined period of time, a change in the gas flow is achieved by changing the position of the steering means 29, 30. The steering means (A) 29 now connects the gas duct 17, which comes out of the desiccant pot (A) 20, via the steering means (B) 30 with the environment. The second gas guide channel 17, which comes from the desiccant pot (B) 21, is connected via the steering means (A) 29 to the gas guide channel 17 to the bulk goods container 11. Furthermore, the heater (A) 22 is turned on. The drying agent 24 is now regenerated in the drying agent pot (A) 20, while the dehumidifying of the gas flowing through takes place in the drying agent pot (B) 21. Due to the special arrangement of the steering means 29, 30, it is possible to achieve continuous dehumidification of a gas stream with only a single fan. In this case, a gas stream is dehumidified in a desiccant pot 20, 21 and the desiccant 24 contained is temporarily regenerated simultaneously in the second desiccant pot 20, 21. The change of the desiccant pot 20, 21, which is respectively active for gas dehumidification, takes place via the steering means 29, 30 and the heating devices 22, 23 and is controlled via a control device 33, wherein the control can also include a regulation. The timing, which was shown in the figure descriptions 1 and 3 to 5, takes place alternately for both desiccant pots 20, 21 depending on the position of the steering means 29, 30. The period of time until the gas streams change and thus the change of the desiccant pot 20, 21 used for gas dehumidification is preferably predefined as a function of the desired drying capacity, but it is also conceivable that this period of time was determined by the respective process parameters, such as recorded temperatures Make moisture, bulk quantity and heating and blower performance dependent. The time period could be set individually by the control device 33.

Claims

claims

1. Device for drying a gas stream, in particular for a bulk material dryer, comprising at least two desiccant pots (20, 21), steering means (29, 30) and gas guide channels (17), the desiccant pots (20, 21) each having an inlet (25), having an outlet (26), a heating device (22, 23) and a drying agent (24), the drying agent (24) being arranged between the inlet (25) and the outlet (26), the heating device (22, 23) is provided for heating the gas flow and / or the desiccant, the steering means (29, 30) being provided for guiding the gas flow, and the gas guide channels (17) correspondingly connected to the desiccant pots (20, 21), characterized in that that a single blower (19) is provided which is correspondingly connected to the desiccant pots (20, 21) and wherein the steering means (29, 30) is arranged in the gas flow direction after the desiccant pots (20, 21) dnet is.

2. Device according to claim one, characterized in that a single temperature sensor (27, 28) is provided for detecting the temperature in the gas flow, which is arranged in the gas flow direction after the desiccant pots (20, 21) and corresponding to these and wherein the steering means (29, 30) is correspondingly connected to the temperature sensor (27, 28).

3. Apparatus according to claim one, characterized in that at least two temperature sensors (27, 28) are provided for detecting the temperature in the gas flow, which are arranged in the gas flow direction after the desiccant pots (20, 21) and corresponding to them and wherein the steering means (29, 30) are correspondingly connected to the temperature sensors (27, 28).

4. Device according to one of the preceding claims, characterized in that the heating devices (22, 23) of the desiccant pots (20, 21) are controllable as a function of the temperature prevailing in the gas stream and the position of the steering means (29, 30).

5. Device according to one of the preceding claims, characterized in that the heating devices (22, 23) of the desiccant pots (20, 21), the temperature sensors (27, 28) and the steering means (29, 30) via a control device (33) , are correspondingly connected to each other.

6. The device according to claim 4, characterized in that a heater (31) is provided for heating the gas flow, the heating power of the heater (31) and / or the blower power of the blower (19) being changeable by means of the control device (33).

7. A method for drying a gas stream, in particular a drying gas from a bulk material dryer, in which a gas stream containing moisture is fed via gas guide channels (30) through an inlet (25) to a desiccant pot (20, 21), the moisture being applied to a, in the desiccant pot (20, 21) arranged desiccant (24) is dispensed, and the dehumidified gas stream leaves the desiccant pot (20, 21) via an outlet (26) again, the desiccant (24) being regenerated after reaching a certain moisture saturation, the Regeneration of the drying agent (24) takes place with a regeneration gas and the gas flow and the regeneration gas flow are controlled with steering means (29, 30), characterized in that a single blower (19) is provided, the gas flow conveyed by the blower (19) is divided into partial streams, with the len arranged in the flow direction after the desiccant pots control means (29, 30) control the gas flows in such a way that a first partial flow flows through a first desiccant pot (20, 21) for dehumidifying the gas flow, and that at times at the same time a second partial flow as the regeneration gas flow the desiccant (24) in a second desiccant pot (20, 21) regenerated, this second partial stream being used to cool the desiccant (24) after the dehumidification of the desiccant (24), the regeneration of the desiccant (24) being formed by the dehumidification and the subsequent cooling of the desiccant (24) ,

8. The method according to claim 7, characterized in that the temperature of the regeneration gas leaving the desiccant (24) is detected by means of temperature sensors (27, 28).

9. The method according to any one of claims 7 or 8, characterized in that the

The gas flow is directed by the steering means (29, 30) arranged in the gas flow direction after the desiccant pots (20, 21), depending on the temperatures of the regeneration gas flow detected by the temperature sensors (27, 28) and additionally in a specifically predetermined time period.

10. The method according to any one of claims 7 to 9, characterized in that at least two heating devices (22, 23) are provided, which are provided for heating the gas stream and / or the drying agent (24), the heating devices (22, 23) as a function of the temperatures of the regeneration gas flow detected by the temperature sensors (27, 28) and the position of the steering means (29, 30).

11. The method according to any one of claims 7 to 10, characterized in that the heating device (22, 23) of the desiccant pot (20, 21) being regenerated is switched off when a certain temperature in the regeneration gas stream is exceeded.

12. The method according to any one of claims 7 to 11, characterized in that the steering means (29, 30) arranged in the gas flow direction after the desiccant pots (20, 21) direct the gas flow in such a way that when the temperature falls below a predetermined temperature, through the outlet ( 26) of the regenerated desiccant pot (20, 21) flowing gas, this flow path is closed and the entire gas flows through the desiccant pot (20, 21) dehumidifying the gas stream.

13. The method according to any one of claims 7 to 12, characterized in that the steering means (29, 30) arranged in the gas flow direction after the desiccant pots (20, 21) steer the gas flow in such a way that part of the regeneration of the desiccant (24) used heat, which is in the desiccant (24) after the dehumidification of the desiccant (24) is used to heat the gas stream.