Method for drying ceramic moulded bodies in a drying chamber

Abstract

A method for drying ceramic molded parts (1) in a drying room (2) is proposed, wherein a circulating gas stream (3) is generated within the drying room (2) by means of circulating fans (4) installed in the drying room (2), wherein at least one heat exchanger (5) of a heating device (6) is arranged in the drying room (2) adjacent to at least one circulating fan (4) of the circulating fans (4) and the at least one heat exchanger (5) is passed through by at least a part of the circulating gas stream (3), wherein - during a drying phase - the part of the circulating gas stream (3) passing through the at least one heat exchanger (5) is heated by the heat exchanger (5) by a maximum of 15 degrees Celsius.

Description

[0001] The invention relates to a method for drying ceramic molded parts in a drying room according to claim 1.

[0002] In the production of ceramic goods, moist ceramic molds or blanks are typically dried in a drying chamber of a kiln and then fired in a kiln. Drying, along with firing, is one of the most energy-intensive processes in the ceramic industry.

[0003] A disadvantage of the known dryers is that a large part of the latent heat energy is lost as moist, heated exhaust air, which results in a low efficiency of the dryer.

[0004] The object of the invention is therefore to provide a method of the type mentioned above, with which the aforementioned disadvantages can be avoided and with which ceramic molded parts can be dried efficiently.

[0005] According to the invention, this is achieved by the features of claim 1.

[0006] This offers the advantage of efficient drying of ceramic molded parts. Since the circulation fans and the heat exchanger are arranged close together in the drying chamber, a high volume flow rate can be achieved through the heat exchanger with comparatively low power consumption. This ensures sufficient heat supply for drying even with a relatively small temperature increase of the gas flow in the heat exchanger. As a result, heat sources for drying can be used that are only slightly warmer than the interior of the drying chamber, thus making the drying process more efficient. Furthermore, it has been shown that the close proximity of the at least one heat exchanger and the at least one circulation fan in the drying chamber minimizes flow resistance.

[0007] The invention further relates to a dryer according to claim 8.

[0008] The invention therefore further aims to provide a dryer of the type mentioned above, with which the aforementioned disadvantages can be avoided and with which ceramic molded parts can be dried more efficiently.

[0009] According to the invention, this is achieved by the features of claim 8.

[0010] The advantages of the dryer are equivalent to the advantages of the aforementioned method.

[0011] The dependent claims relate to further advantageous embodiments of the invention.

[0012] The invention is described in more detail with reference to the attached drawing, in which only one preferred embodiment is shown by way of example. The drawing shows: Fig. 1 A schematic representation of a preferred embodiment of a dryer.

[0013] The Fig. 1 Figure 1 shows at least parts of a preferred embodiment of a dryer 9 for drying ceramic molded parts 1 comprising a drying chamber 2, circulating fans 4 and a heating device 6, wherein the circulating fans 4 are arranged within the drying chamber 2 to generate a circulating gas flow 3 in the drying chamber 2, wherein at least one heat exchanger 5 of the heating device 6 is arranged in the drying chamber 2 adjacent to at least one circulating fan 4 of the circulating fans 4 and the at least one heat exchanger 5 is passable through at least a part of the circulating gas flow 3, wherein - during a drying phase - the part of the circulating gas flow 3 passing through the at least one heat exchanger 5 can be heated by the heat exchanger 5 by a maximum of 15 degrees Celsius.

[0014] Furthermore, a method for drying ceramic molded parts 1 in a drying room 2 is provided, wherein a circulating gas stream 3 is generated within the drying room 2 by means of circulating fans 4 installed in the drying room 2, wherein at least one heat exchanger 5 of a heating device 6 is arranged in the drying room 2 adjacent to at least one circulating fan 4 of the circulating fans 4 and the at least one heat exchanger 5 is flowed through by at least a part of the circulating gas stream 3, wherein - during a drying phase - the part of the circulating gas stream 3 flowing through the at least one heat exchanger 5 is heated by the heat exchanger 5 by a maximum of 15 degrees Celsius.

[0015] This offers the advantage that ceramic molded parts 1 can be dried efficiently. Since the circulation fans 4 and the heat exchanger 5 are arranged adjacent to each other in the drying chamber 2, it is possible to convey a high volume flow through the heat exchanger 5 with comparatively low power consumption. This ensures that even with a relatively small temperature increase of the gas flow in the heat exchanger 5, sufficient heat is supplied for drying. As a result, heat sources for drying can be used that are only slightly warmer than the interior of the drying chamber 2, thus making the drying process more efficient. It has been shown that the adjacent arrangement of the at least one heat exchanger 5 and the at least one circulation fan 4 in the drying chamber 2 keeps the corresponding flow resistances low.

[0016] The method according to the invention is suitable for drying ceramic molded parts 1 in a drying room 2.

[0017] The ceramic molded parts 1 typically have a certain moisture content before drying to facilitate shaping. Preferably, the moisture content or water content of the ceramic molded parts 1 can be between at least 20 percent and at most 40 percent.

[0018] The moisture content of the ceramic molded parts 1 is reduced in the dryer 9, especially in the drying chamber 2.

[0019] The drying chamber 2 is preferably the chamber in a dryer suitable for drying molded parts. The dryer 9 can preferably be a chamber dryer or a tunnel dryer. Chamber dryers and tunnel dryers are dryers known to those skilled in the art. The method according to the invention can be used with these dryers. Such dryers are known to those skilled in the art, so a further embodiment of these dryers is omitted.

[0020] The dryer 9 is a device for drying goods, in particular ceramic molded parts 1. The dryer 9 comprises a drying chamber 2, circulating fans 4 and a heating device 6.

[0021] Ceramic molded parts 1 can also be referred to as ceramic blanks. These ceramic molded parts 1 may preferably be undried or unfired earthenware, such as construction ceramics or refractory ceramics, sintered materials, such as stoneware or porcelain, and special ceramic materials, such as electroceramics. The ceramic molded parts 1 may preferably be undried and unfired bricks, roof tiles, floor tiles, or wall tiles.

[0022] Drying chamber 2 has a gas inlet 7 and a gas outlet 8. The gas inlet 7 and the gas outlet 8 are in Fig. 1 As shown by way of example. The gas inlet 7 is designed to introduce fresh air 10 into the drying chamber 2. The gas outlet 8 is designed to discharge exhaust air 11 from the drying chamber 2. The fresh air 10 is preferably a gas that is introduced into the drying chamber 2. The fresh air 10 is the gas stream introduced through the gas inlet 7. The exhaust air 11 is preferably a gas that is discharged from the drying chamber 2, in particular moist and heated air from the drying chamber 2. The exhaust air 11 is the gas stream discharged through the gas outlet 8.

[0023] Preferably, the amount of fresh air 10 that can be introduced into the drying chamber 2 through the gas inlet 7 and the amount of exhaust air 11 that can be discharged from the drying chamber 2 through the gas outlet 8 can be predetermined. This can be achieved, for example, by means of an adjustable valve.

[0024] It can be provided that - viewed in the direction of flow of the circulating gas stream 3 - the gas outlet 8 is arranged before the flow through the ceramic molded parts 1.

[0025] Particularly preferably, it may be provided that - viewed in the direction of flow of the circulating gas stream 3 - the gas outlet 8 is arranged after the flow through the ceramic molded parts 1.

[0026] Preferably, the gas flow 10 or the fresh air 10 introduced through the gas inlet 7 can be preheated, in particular before being introduced into the drying chamber 2, by means of an auxiliary heater, in particular a burner, preferably a gas burner. The burner is a device for converting chemical energy, for example a liquid or gaseous fuel, in particular gas, kerosene, diesel or the like, into thermal energy. This allows the temperature in the dryer 9 to be controlled even more precisely.

[0027] Preferably, the gas flow 10 or the fresh air 10 introduced through the gas inlet 7 can be preheated, at least partially, by means of the gas flow 11 or the exhaust air 11 discharged from the gas outlet 8, particularly by means of a portion of the gas flow 11 or the exhaust air 11 discharged from the gas outlet 8. An additional heating element can also preferably be provided. This allows for even more precise temperature control in the dryer 9.

[0028] The fact that at least one heat exchanger 5 is arranged in the drying room 2 adjacent to at least one of the circulation fans 4 means in particular that this circulation fan 4 and the heat exchanger 5 are arranged at least partially, preferably directly, one behind the other in terms of flow technology.

[0029] Preferably, viewed in the direction of flow of the circulating gas stream 3, the gas inlet 7 is arranged on the drying chamber 2, followed by at least one circulating fan 4 located adjacent to the at least one heat exchanger 5. This is exemplified in Fig. 1 This demonstrates that particularly efficient heat transfer from the heat exchanger 5 to the portion of the circulating gas stream 3 flowing through the heat exchanger 5 can be achieved. Furthermore, fresh air 10 can be efficiently introduced into the drying chamber 2 without significantly affecting the heat transfer to the circulating gas stream 3.

[0030] Particularly preferably, it can be provided that – during the drying phase – the average temperature at the gas inlet 7 of the drying chamber 2 is at least 20 degrees Celsius, preferably at least 25 degrees Celsius, and particularly at least 30 degrees Celsius. This allows for particularly efficient operation of the dryer 9.

[0031] Particularly preferably, it can be provided that – during the drying phase – the average temperature at the gas inlet 7 of the drying chamber 2 is a maximum of 300 degrees Celsius, preferably a maximum of 275 degrees Celsius, and particularly a maximum of 250 degrees Celsius. This allows for particularly efficient operation of the dryer 9.

[0032] The average temperature at gas inlet 7 is to be measured at the point where the air enters the drying chamber 2.

[0033] It is provided that two circulation fans 4 are installed in the drying chamber 2. The circulation fans 4 are designed to generate a circulating gas flow 3 in the drying chamber 2. The drying chamber 2 can be enclosed by a housing, particularly one that is thermally insulated, with the circulation fans 4 arranged inside the housing. The circulation fans 4 can also be referred to as internal recirculation fans. Preferably, axial and / or radial fans can be used as the circulation fans 4. Preferably, at least one of the circulation fans 4 is an axial or radial fan.

[0034] Preferably, at least 6, in particular at least 12, preferably at least 24, circulating fans 4 are arranged in the drying room 2.

[0035] Preferably at least 20 percent, in particular at least 40 percent, preferably at least 60 percent, of the circulating fans 4 arranged in the drying room 2 can be arranged substantially adjacent to the at least one heat exchanger 5 arranged in the drying room 2.

[0036] In the method according to the invention, the circulation fans 4 generate a circulating gas flow 3 in the drying chamber 2. Fig. 1 Only one circulating fan 4 is shown as an example, arranged adjacent to the heat exchanger 5. The circulating gas flow 3 is located within the drying chamber 2. This is illustrated by example in Fig. 1 As can be seen, the reference numerals 3 are shown by way of example to the circulating gas flow 3 after passing through the ceramic molded parts 1, after exiting the circulating fan 4, and before entering the ceramic molded parts 1. The circulating gas flow 3 is a circulating gas flow, i.e., a gas flow running in a circle, in the drying chamber 2, which is heated at least partially per revolution by the at least one heat exchanger 5.

[0037] It is particularly preferred that the heat exchanger 5 is arranged directly in the drying chamber 2. The drying chamber 2 is provided to be a single, open space without a bypass line or enclosed compartments. In the case of a tunnel dryer, the drying chamber 2 preferably has a tunnel inlet opening, a tunnel outlet opening, and a tunnel wall. In the case of a chamber dryer, the drying chamber 2 preferably has a chamber with six enclosed sides. This allows for efficient heat flow within the drying chamber 2 and particularly good heat transfer from the heat exchanger 5 to the circulating gas stream 3, which would not be achievable if the circulating gas stream 3 were heated in a bypass line or in an enclosed compartment within the drying chamber 2.

[0038] Particularly preferably, the method may provide that the circulation fans 4 are operated with a total volume flow of at least 150 m³ / h per cubic meter of drying chamber volume during the drying phase. The total volume flow refers to the combined volume flows of all circulation fans 4 arranged in the drying chamber 2. In the case of multiple circulation fans 4, it is preferably provided that the individual circulation fans 4 have different power ratings, with differing efficient operating modes for each fan. Therefore, the method may preferably provide that the circulation fans 4 can be operated at a higher power rating, but for efficiency reasons, they are operated at a lower volume flow rate than their maximum achievable volume flow rates.Furthermore, it may also be preferably provided that the at least one circulating fan 4, which has the smallest distance to the heat exchanger 5, is operated with a higher volume flow rate than the volume flow rate with which the circulating fan 4 can be operated most efficiently, thereby increasing the amount of the part of the circulating gas flow 3 which flows through the heat exchanger 5.

[0039] In particular, the recirculating gas flow 3 is greater than the exhaust air flow 11 from the gas outlet 8. The exhaust air flow 11 typically corresponds approximately to the fresh air flow through the gas inlet 7 into the dryer. Heat exchangers 5 located outside the dryer could therefore be operated with a correspondingly smaller volume of air for supplying warm air to the dryer than with internally arranged heat exchangers 5. Furthermore, the typical designs of dryers for drying ceramic molded parts 1 allow for a structurally advantageous design of the dryer's internal heat exchangers 5, which is adapted to the increased airflow.

[0040] It is particularly preferred that the dryer 9 is configured such that the circulation fans 4 have a total achievable volume flow rate of at least 150 m³ / h per cubic meter of drying chamber volume. In this device, the total volume flow rate is the maximum achievable volume flow rate of all circulation fans 4 in the drying chamber 2.

[0041] The total volume flow rate of the circulating fans 4 is particularly preferred to be at least 5 times greater than the volume flow rate through the gas outlet 8 and / or the gas inlet 7.

[0042] Preferably, the circulating fans 4 may have a total generable volume flow of at least 500,000 m³ / h, in particular at least 750,000 m³ / h, preferably at least 1,000,000 m³ / h.

[0043] Preferably, the circulating fans 4 can generate a total volume flow of a maximum of 7,000,000 m³ / h, in particular a maximum of 4,000,000 m³ / h, preferably a maximum of 3,000,000 m³ / h, and most preferably a maximum of 2,000,000 m³ / h.

[0044] The drying room volume is the volume or space content of the drying room 2.

[0045] Volume flow rate is a physical quantity and is usually found in the data sheets of fans. It indicates how much volume of a fluid is transported through a defined cross-section per unit of time.

[0046] According to the invention, at least one heat exchanger 5 of a heating device 6 is arranged in the drying chamber 2. The at least one heat exchanger 5 is arranged adjacent to at least one of the circulation fans 4. Due to the adjacent arrangement of the at least one circulation fan 4 to the heat exchanger 5, particularly efficient heat transfer from the heat exchanger 5 to the circulating gas stream 3 can be achieved. As a result, during the drying phase, a temperature increase of a maximum of 15 degrees Celsius in the portion of the circulating gas stream 3 flowing through the heat exchanger 5 is sufficient to achieve efficient drying of the ceramic molded parts 1. Due to the adjacent arrangement of the circulation fan 4 and the heat exchanger 5, a portion of the circulating gas stream 3 can be efficiently drawn or forced through the heat exchanger 5.

[0047] Preferably, several heat exchangers 5 of the heating device 6 can be arranged in the drying room 2.

[0048] Preferably, at least 10, preferably at least 30, preferably at least 50, heat exchangers 5 of the heating device 6 can be arranged in the drying room 2.

[0049] Preferably, the at least one heat exchanger 5 is arranged on a ceiling or wall of the drying room 2. This can promote the formation of the circulating gas flow 3.

[0050] Preferably, at least one of the circulation fans 4 is arranged on the ceiling or a wall of the drying room 2.

[0051] Preferably, viewed in the direction of flow of the circulating gas stream 3, the at least one circulating fan 4 arranged adjacent to the at least one heat exchanger 5 can be arranged downstream of the at least one heat exchanger 5. This is exemplified in Fig. 1 This is evident. As a result, a particularly large portion of the circulating gas flow 3 can be drawn through the heat exchanger 5, which further improves the efficiency of the dryer 9.

[0052] It is particularly preferred that – during the drying phase – the portion of the circulating gas stream 3 flowing through the at least one heat exchanger 5 is drawn through the heat exchanger 5 by means of the circulating fans 4. This allows for a particularly good heat transfer from the heat exchanger 5 to the circulating gas stream 3. This promotes a low temperature of the heat exchanger 5, thereby improving the efficiency of the dryer 9, in particular the heating device 6.

[0053] Preferably, the portion of the circulating gas flow 3 passing through the heat exchanger 5 is drawn or pushed by means of the circulating fans 4 - viewed in the direction of flow of the circulating gas flow 3 - from a first end of the heat exchanger 5 to a second end of the heat exchanger 5 opposite the first end and spaced apart from the first end.

[0054] During the drying phase, the portion of the circulating gas stream 3 flowing through the at least one heat exchanger 5 is heated by a maximum of 15 degrees Celsius. This temperature increase is the temperature of the circulating gas stream 3 after exiting the second end of the heat exchanger 5 compared to the temperature of the circulating gas stream 3 before entering the first end of the heat exchanger 5. The temperature increase is therefore determined by measuring the temperature of the circulating gas stream 3 immediately before entering the heat exchanger 5 (at the first end) and immediately after exiting the heat exchanger 5 (at the second end), and then calculating the difference between the measured values. Preferably, several measurements are taken and the arithmetic mean of the determined differences is calculated.

[0055] Preferably, the second end of the heat exchanger 5 faces the at least one circulating fan 4, which circulating fan 4 is arranged adjacent to the heat exchanger 5.

[0056] The dryer 9 is designed to include the heating device 6. The heating device 6 is a device for providing heat to the drying chamber 2. For this purpose, the heating device 6 includes at least one heat exchanger 5. The heat exchanger 5 can preferably also be referred to as a heat exchanger or heat transfer unit and is a device known to a person skilled in the art. The at least one heat exchanger 5 is arranged in the drying chamber 2 and transfers the generated heat to the drying chamber 2, in particular to the circulating gas stream 3.

[0057] Preferably, the heating device 6 can comprise a heating circuit 12. This is exemplified in Fig. 1 As can be seen. Preferably, a fluid is circulated in a closed loop in the heating circuit 12. Preferably, a heating circuit pump 13 can be provided in the heating circuit 12. The heating circuit pump 13 is part of the heating circuit 12. By means of the heating circuit pump 13, the fluid of the heating circuit 12, for example a liquid, in particular water, or a gas, can be circulated.

[0058] Particularly preferably, the heating device 6 includes a heat pump 23. Preferably, the fluid in the heating circuit 12 is heated by means of the heat pump 23. Preferably, the heated fluid can be conveyed to the heat exchanger 5 in the drying chamber 2 by means of the heating circuit pump 13. In the drying chamber 2, the heat exchanger 5 can transfer the heat to the environment, in particular to the portion of the circulating gas stream 3 flowing through the heat exchanger 5. This allows for the use of a particularly environmentally friendly heating system for operating the dryer 9. In synergy with the adjacent arrangement of the at least one heat exchanger 5 and the at least one circulating fan 4, as well as the heating – during the drying phase – of the portion of the circulating gas stream 3 flowing through the at least one heat exchanger 5 by a maximum of 15 degrees Celsius, a particularly efficient operation of the heat pump 23 can be achieved.This synergistic effect significantly improves the efficiency of the heat pump 23, as the heat pump 23 requires a smaller temperature difference between the "cold side" and the "hot side." The "cold side" is the side of the heat pump 23 that is normally supplied with heat from the heat source. In the present invention, the "cold side" is the energy that is at least partially extracted from the exhaust air 11 of the dryer 9, i.e., from the gas flow that is discharged through the gas outlet 8 of the drying chamber 2. The "hot side" is the energy that the heat pump 23 must supply to the heat exchanger 5. This allows the COP value of the heat pump 23 to be increased.

[0059] Alternatively, instead of the heat pump 23, the heating device 6 can preferably comprise a heat exchanger which is thermally coupled to an alternative heat source. The heating device 6 can preferably use process heat, in particular waste heat from another process, for example during firing in a kiln, for drying the ceramic molded parts 1.

[0060] Preferably, it can be provided that - during the drying phase - the part of the circulating gas stream 3 flowing through the at least one heat exchanger 5 is heated by the heat exchanger 5 by a maximum of 12 degrees Celsius, in particular a maximum of 10 degrees Celsius.

[0061] A heat pump is a device known to a person skilled in the art. Preferably, the heat pump 23 can be a compression heat pump. The heat pump 23 preferably comprises a compressor 14, a condenser 15, an expansion valve 16, and an evaporator 17. The compressor 14, the condenser 15, the expansion valve 16, and the evaporator 17 are in Fig. 1 As shown by way of example. In the conventional sense, a working medium or fluid is circulated in the heat pump 23. This means that the fluid absorbs heat in the evaporator 17, causing it to evaporate. It is then compressed in the compressor 14, which increases the temperature of the working fluid. It is condensed or liquefied in the condenser 15 and subsequently expanded through the expansion valve 16. This cycle can also be referred to as the working cycle of the heat pump 23.

[0062] Alternatively, the heat pump 23 can also be an absorption heat pump.

[0063] It is particularly advantageous to provide that the heat pump 23 is thermally coupled to a gas outlet 8 of the drying room 2. This is in Fig. 1 This is illustrated by the arrow pointing to reference numeral 11. This allows the energy of the exhaust air 11, in particular the gas flow discharged through the gas outlet 8, to be used for drying, thereby improving the efficiency of the dryer 9. Thus, thermal energy is recovered.

[0064] Preferably, the heat pump 23 can be thermally coupled to an outlet pipe of the drying chamber 2. The outlet pipe of the drying chamber 2 is preferably a part of the dryer 9. Preferably, a first end of the outlet pipe is connected to the gas outlet 8 of the drying chamber 2. Preferably, the exhaust air not required for heat recovery can be discharged via a second end of the outlet pipe.

[0065] Preferably, the heating device 6 can include a heat recovery circuit 18. This is exemplified in Fig. 1 As can be seen. Preferably, a fluid, in particular a liquid or a gas, is circulated in a closed loop in the heat recovery circuit 18. Preferably, a recovery circuit pump 19 can be provided in the heat recovery circuit 18. The recovery circuit pump 19 is part of the heat recovery circuit 18. By means of the recovery circuit pump 19, the fluid of the heat recovery circuit 18, for example a liquid, in particular water, or a gas, can be circulated. Preferably, the heat pump 23 can be thermally coupled to the gas outlet 8 of the drying chamber 2 via the heat recovery circuit 18.

[0066] Preferably, the heat recovery circuit 18 is routed at least partially in the outlet pipe of the drying room 2. Preferably, a heat exchanger of the heat recovery circuit 18 is arranged in the outlet pipe of the drying room 2. This allows heat from the exhaust air from the outlet pipe, in particular via the heat exchanger in the outlet pipe, to be absorbed and supplied to the heat pump 23.

[0067] Preferably, the heat recovery circuit 18 can be at least partially conducted in a heat absorption chamber 20. This is exemplified in Fig. 1 As can be seen. Preferably, the heat absorption chamber 20 is thermally coupled to the gas outlet 8 of the drying chamber 2. Preferably, a heat exchanger 22 of the heat recovery circuit 18 is arranged in the heat absorption chamber 20. This allows heat from the exhaust air 11 from the drying chamber 2 to be transferred into the heat absorption chamber 20 and heat the heat absorption chamber 20. The exhaust air 11 can be passed completely or at least partially through the heat exchanger 22, which cools the gas stream 11, causes water vapor to condense, and releases energy. This allows heat to be absorbed from the heat absorption chamber 20, particularly via the heat exchanger 22 in the heat absorption chamber 20, and supplied to the heat pump 23.

[0068] Preferably, a condensate drain line 21 can be arranged in the outlet line or the heat absorption chamber 20. Preferably, condensate formed in the outlet line or the heat absorption chamber 20 can be drained away by means of the condensate drain line 21. This is exemplified for the heat absorption chamber 20 in Fig. 1 shown.

[0069] Alternatively, instead of using the heating circuit 12, the heat exchanger 5 can be the condenser 15 of the heat pump 23. In this preferred embodiment, the condenser 15 of the heat pump 23 is located in the drying chamber 2. In this case, the heating circuit 12 can be omitted, since the fluid heated by the heat pump 23 can release the heat in the drying chamber 2 via the condenser 15 after compression. This allows for a simpler design of the dryer 9.

[0070] Preferably, liquids or gases are used as the fluid in the heating device 6, which are particularly well suited as working fluids in heat pumps 23. The boiling point of the fluid can play a role in the choice of fluid, but environmental aspects can also influence the choice of fluid, so that a special fluid does not have to be used for the working circuit, the heating circuit 12 and / or the heat recovery circuit 18 of the heat pump 23.

[0071] Thermally coupled according to the invention means that components, circuits, or at least one component and a circuit are connected in such a way that heat or thermal energy can be transferred or supplied from one component to one or more other components, from one circuit to one or more other circuits, from one component to another circuit, or from one circuit to another component. The thermal coupling can be achieved in particular by means of heat transfer devices. The thermal coupling can be direct or indirect via intermediate circuits.

[0072] Preferably, the dryer 9 can be operated in different phases, in particular in a heating phase and / or a drying phase. Preferably, in the heating phase, the temperature in the drying chamber 2 is continuously increased. Preferably, in the drying phase, the temperature in the drying chamber 2 is kept constant for at least a predefinable period of time. The temperature in the drying chamber 2 is the average temperature at different points in the drying chamber 2.

[0073] Preferably, the dryer 9 can include a control unit for carrying out the method according to the invention. Preferably, the control unit controls the heating device 6 and / or the circulation fans 4 and / or valves that control the inflow of a gas stream via the gas inlet 7 and the outflow of a gas stream via the gas outlet 8, and / or pumps, in particular the heating circuit pump 12 and / or the recovery circuit pump 19.

[0074] For drying the ceramic molded parts 1, the ceramic molded parts 1 are preferably placed in the dryer 9, in particular the chamber dryer or the tunnel dryer. In the case of the tunnel dryer, the dryer 9 is preferably already in operation, or in the case of the chamber dryer, the dryer 9 is preferably started up. The drying chamber 2 of the dryer 9 is heated by means of the heating device 6. In addition, the drying chamber 2 can preferably be heated by the introduced heated fresh air 10. The recirculating gas stream 3 is generated in the drying chamber 2 by means of the circulating fans 4, and a portion of the recirculating gas stream 3 is drawn through the heat exchanger 5. This allows for particularly good heat transfer from the heat exchanger 5 to the recirculating gas stream 3. A gas stream can be discharged from or drawn off the drying chamber 2 via the gas outlet 8. This gas stream is the exhaust air 11.The exhaust air 11 can be used for heat recovery by the heating unit 6, in particular by means of the heat pump 23. This allows the temperature difference at the heat pump 23 to be kept small, thereby improving the efficiency of the heat pump 23 and enabling the dryer 9 to be operated particularly efficiently.

[0075] The following are principles for understanding and interpreting the disclosure in question.

[0076] Characters are usually introduced with an indefinite article "ein, eine, eines, einer". Unless the context indicates otherwise, "ein, eine, eines, einer" should therefore not be understood as a numeral.

[0077] Value ranges include the endpoints unless the context indicates otherwise.

Claims

1. Method for drying ceramic molded parts (1) in a drying room (2), wherein a circulating gas stream (3) is generated within the drying room (2) by means of circulating fans (4) installed in the drying room (2), wherein at least one heat exchanger (5) of a heating device (6) is arranged in the drying room (2) adjacent to at least one circulating fan (4) of the circulating fans (4) and the at least one heat exchanger (5) is passed through by at least a part of the circulating gas stream (3), wherein - during a drying phase - the part of the circulating gas stream (3) passing through the at least one heat exchanger (5) is heated by the heat exchanger (5) by a maximum of 15 degrees Celsius.

2. Method according to claim 1, characterized by the fact that - during the drying phase - the part of the circulating gas flow (3) flowing through the at least one heat exchanger (5) is drawn through the heat exchanger (5) by means of the circulating fans (4).

3. Method according to claim 1 or 2, characterized by the fact that - during the drying phase - an average temperature at a gas inlet (7) of the drying chamber (2) is at least 20 degrees Celsius, preferably at least 25 degrees Celsius, in particular at least 30 degrees Celsius.

4. Method according to claim 1 or 2, characterized by the fact that - during the drying phase - the average temperature at a gas inlet (7) of the drying chamber (2) is a maximum of 300 degrees Celsius, preferably a maximum of 275 degrees Celsius, and in particular a maximum of 250 degrees Celsius.

5. Method according to any one of claims 1 to 4, characterized by the fact that per cubic meter of drying room volume, the circulation fans (4) - during the drying phase - with a total volume flow of at least 150 m³ 3 / h 6. Method according to any one of claims 1 to 5, characterized by the fact that the heating system (6) includes a heat pump (23).

7. Method according to claim 6, characterized by the fact thatthe heat pump (23) is thermally coupled to a gas outlet (8) of the drying room (2).

8. Dryer (9) for drying ceramic molded parts (1), in particular according to a method according to claims 1 to 7, comprising a drying chamber (2), circulating fans (4) and a heating device (6), wherein the circulating fans (4) are arranged within the drying chamber (2) to generate a circulating gas flow (3) in the drying chamber (2), wherein at least one heat exchanger (5) of the heating device (6) is arranged in the drying chamber (2) adjacent to at least one circulating fan (4) of the circulating fans (4) and the at least one heat exchanger (5) is passable through at least a part of the circulating gas flow (3), wherein - during a drying phase - the part of the circulating gas flow (3) passing through the at least one heat exchanger (5) can be heated by the heat exchanger (5) by a maximum of 15 degrees Celsius.

9. Dryer (9) according to claim 8, characterized by the fact that the heat exchanger (5) is located directly in the drying room (2).

10. Dryer (9) according to claim 8 or 9, characterized by the fact that the circulation fans (4) must generate a total volume flow of at least 150 m³ 3 / h per cubic meter of drying room volume.

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