Drying system and method for drying a product

Abstract

The invention relates to a drying system (10) and a method for drying a product (12), in particular a medical product, electronic product, food product or the like, the drying system comprising a process chamber (11), in which the product can be disposed, and a heating unit for heating the process chamber and / or the product. The drying system comprises a moisture measurement unit (19) having a trace moisture measurement device (20) for measuring residual moisture, in particular in the process chamber.

Description

[0001] Drying system and method for drying a product

[0002] The invention relates to a drying system and a method for drying a product, in particular a medical product, electronic product, food product or the like, comprising a process space in which the product can be arranged, and a heating unit for heating the process space and / or the product.

[0003] A drying system of the type described above is known in practice and is regularly used to dry or dehumidify a product, such as a medical device, electronic product, food product, or the like, in a trace moisture range. The term "trace moisture" refers to a small amount of moisture in the ppm range, in particular a range of < 1000 ppm.

[0004] Such a drying system typically comprises a process chamber in which the product can be arranged, and a heating unit for heating the process chamber and / or the product. To carry out a drying process, the product is then placed in the process chamber, dried by heating the process chamber and / or the product, and removed from the process chamber as dried after a certain drying time has been reached. The aim is to ensure that the trace moisture remaining in the dried product, also referred to as the residual moisture of the product, falls below a target moisture content.However, since the drying time in the drying system known from practice is based exclusively on empirical values, it frequently happens that a product either does not remain in the processing chamber long enough, resulting in the residual moisture content being above the desired target moisture content, or that a product remains in the processing chamber longer than necessary, resulting in inefficient use of energy costs and processing time. This generally results in increased waste and / or increased processing costs.

[0005] The present invention is therefore based on the object of proposing a drying system and a method which enables cost-effective drying of a product while at the same time reducing waste.

[0006] This object is achieved by a drying system having the features of claim 1 and a method having the features of claim 12.

[0007] The drying system according to the invention for drying a product, in particular a medical product, electronic product, food product or the like, comprises a process chamber in which the product can be arranged, and a heating unit for heating the process chamber and / or the product, wherein the drying system comprises a moisture measuring unit with a trace moisture measuring device for measuring a residual moisture, in particular in the process chamber.

[0008] The drying system according to the invention is suitable for drying or dehumidifying a solid product, such as a medical device, electronic product, food product, or the like, and can be used to dry or dehumidify the product in the trace moisture range or ppm range. The product can be dried or dehumidified by means of the drying system in such a way that the moisture or material moisture inherent in the product, after drying by means of the drying system, is in the trace moisture range, in particular <1000 ppm. If the moisture or material moisture of the product is already in the trace moisture range before drying, the residual moisture of the product can be further reduced by means of the drying system.

[0009] The drying system according to the invention comprises a process chamber in which the product can be arranged, and a heating unit for heating the process chamber and / or the product. The product can therefore be heated directly and / or the product can be heated indirectly by heating the process chamber. The heating of the product and / or the process chamber brings about a temperature control of the product and / or the process chamber or, in particular, of the process air located in the process chamber. As a result, liquids or liquid mixtures of substances, in particular water and / or solvents, present in the product, for example in capillaries, which are responsible for moisture or material moisture or residual moisture in the product are converted into a gaseous state and can escape from the product into the process air surrounding the product to dehumidify or dry the product. This can lead to a measurable increase in moisture orResidual moisture in the process air.

[0010] The drying system according to the invention comprises a moisture measuring unit with a trace moisture measuring device, i.e. a moisture measuring device configured to measure trace moisture, for measuring or determining trace moisture or residual moisture of the product or trace moisture or residual moisture in the process chamber or the process air located in the process chamber. The residual moisture is trace moisture within the trace moisture range. The trace moisture measuring device can be provided or configured, in particular, to measure the residual moisture of the process air, from which the residual moisture of the product can be determined or from which the residual moisture of the product can be deduced. The drying system according to the invention thus enables measurement or determination of the residual moisture of the product or the residual moisture in the process chamber or the process air located in the process chamber during a drying process.During a drying process, it is always possible to compare the current residual moisture content of the product or the current residual moisture content in the process chamber or process air with a desired target moisture content and to optimally adjust the drying time to the product. Energy costs and process time can thus be efficiently utilized and waste reduced. Therefore, the drying system according to the invention enables cost-effective drying of a product while simultaneously reducing waste.

[0011] During a drying process or heating of the process chamber and / or the product, a vacuum can be created in the process chamber, at least temporarily, to perform vacuum drying. This can lower the boiling point of the liquids or liquid mixtures according to a vapor pressure curve, allowing them to evaporate at comparatively lower temperatures. This type of vacuum drying is particularly gentle on the product and can even reach hard-to-reach areas within product geometries.

[0012] The drying system may comprise a housing, particularly a cabinet-like housing. Accordingly, the drying system may be designed as a drying cabinet. The housing may have a door, which, when opened, allows access to the process chamber for placing the product in the process chamber and for removing the dried product from the process chamber. The drying system may comprise a temperature measuring unit for measuring a temperature in the process chamber or the process air and / or the product.

[0013] The drying system may comprise a pressure measuring unit for measuring a pressure in the process space or the process air.

[0014] The heating unit can be designed to heat the process chamber or the process air and / or the product to a temperature of up to +200 °C or more.

[0015] Advantageously, the heating unit can be designed as a jacket heater. The process chamber or the housing can have a jacket that surrounds the process chamber. The heating unit can then heat the process chamber from all sides. A heat transfer medium can flow through the jacket. An oil-based heat transfer medium can preferably be used as the heat transfer medium. Designing the heating unit as a jacket heater ensures that potentially explosive atmospheres within the process chamber do not pose a threat to process safety.

[0016] Advantageously, the drying system may comprise a recirculation unit for circulating process air in the process chamber in order to achieve optimized heating of the process chamber or the process air and / or the product.

[0017] Advantageously, the drying system may comprise an inlet for supplying process air or supply air into the process chamber.

[0018] Advantageously, the drying system can comprise an outlet for removing process air or exhaust air from the process chamber. Advantageously, the recirculation unit can comprise a recirculation duct connected to the outlet and the inlet or connecting the inlet to the outlet, wherein the recirculation unit can comprise a circulation device, preferably a fan, integrated into the recirculation duct, which can be configured to circulate the process air via the recirculation duct to circulate the process air in the process chamber. By means of the circulation device, the process air can then be extracted or removed from the process chamber via the outlet and, after passing through the recirculation duct, fed back into the process chamber via the inlet. This allows a process air flow to be formed in the process chamber, whereby uniform heating of the process chamber or the process air and / or the product can be achieved.The circulation device can comprise a fan or be designed as a fan. The fan can be designed as a radial fan or an axial fan. A drive motor for the fan can be located outside the recirculation duct, with a fan impeller being connected or coupled to the drive motor via a fan shaft.

[0019] The trace moisture measuring device can operate based on the coulometric principle or on the oscillating quartz crystal microbalance principle. Accordingly, the trace moisture measuring device can be designed as a coulometric moisture sensor or a quartz crystal moisture analyzer. Alternatively, the trace moisture measuring device can also be designed as a metal oxide moisture sensor.

[0020] Advantageously, the humidity measuring unit can be integrated into the recirculation duct, such that the residual moisture in the process air discharged from the process chamber can be measured using the trace moisture measuring device. The residual moisture can then be measured while the recirculation unit is operating. The humidity measuring unit or trace moisture measuring device can then preferably be arranged upstream of the circulation device or fan, as viewed in the direction of process air flow.

[0021] In one embodiment of the drying system, the trace moisture measuring device can be arranged in the recirculation duct or integrated into the recirculation duct.

[0022] In an alternative embodiment of the drying system, the moisture measuring unit can comprise a bypass line connected to the recirculating air line, in which bypass line the trace moisture measuring device can be arranged or integrated. Furthermore, the moisture measuring unit can comprise a sample gas pump arranged in the bypass line, preferably downstream of the trace moisture measuring device, and / or a cooling section arranged in the bypass line, preferably upstream of the trace moisture measuring device. The trace moisture measuring device and, if applicable, the sample gas pump and / or the cooling section are then arranged in the bypass line, connected parallel to the recirculating air line. By arranging the trace moisture measuring device in the bypass line, a reduction in the flow velocity of the process air in the recirculating air line can be avoided.A comparatively small amount of process air, which can form a sample gas, can flow through the bypass line and be used to measure the residual moisture. The sample gas pump ensures continuous and precise supply of the trace moisture measuring device. The sample gas can be cooled by means of the cooling section or a cooling device if its temperature is too high for the trace moisture measuring device. The sample gas pump or cooling section is preferably arranged downstream of or upstream of the trace moisture measuring device in the flow direction of the sample gas in the bypass line.

[0023] Advantageously, the drying system can comprise an evacuation unit for evacuating the process chamber. By means of the evacuation unit, process air can be removed from the process chamber or drying system, for example, into an environment, and a vacuum can be created or established in the process chamber. In principle, it is conceivable for the vacuum to be a rough vacuum, a fine vacuum, or a high vacuum. The evacuation unit can be configured to create a pressure of at least <100 mbar in the process chamber.

[0024] Advantageously, the evacuation unit can comprise an evacuation line and an evacuation device, preferably a vacuum pump, integrated into the evacuation line. The evacuation line can preferably be connected to the recirculation line, preferably between the moisture measuring unit or the trace moisture measuring device and the circulation device or the fan, resulting in a simplified arrangement. Furthermore, the residual moisture can thus also be measured during the evacuation. After passing through the moisture measuring unit or the trace moisture measuring device, for example via a three-way valve, the process air can then be either redirected back into the process chamber via the circulation device or the fan, depending on the operating mode of the drying system, or discharged from the drying system via the evacuation unit, for example into the environment.It is also conceivable that the drying system includes an additional outlet to which the evacuation line can be connected.

[0025] Advantageously, the drying system can comprise a heat exchanger integrated into the evacuation line. The heat exchanger can preferably be arranged upstream of the evacuation device or vacuum pump, as viewed in the direction of process air flow in the evacuation line. The heat exchanger can transfer heat from the process air to a cooling medium. This allows energy recovery or cooling of the process air to be extracted or discharged.

[0026] Advantageously, the drying system can comprise a purging unit with at least one purging device for purging the process chamber with a purge gas, in particular an inert gas, preferably nitrogen or dry air. After the process chamber has been purged with the purge gas, optionally after a prior evacuation of the process chamber by means of the evacuation unit, the purge gas can be located in the process chamber or the process chamber can be filled with the purge gas as process air, so that the purge gas can essentially form the process air located in the process chamber. The purge unit can comprise at least one purge line, via which the purge device, preferably viewed in the flow direction of the process air in the recirculation line, follows the circulation device orthe fan, can be connected to the recirculation line, so that the purge gas can reach the process chamber, preferably via the inlet, resulting in a simplified arrangement. It is also conceivable for the drying system to comprise a further inlet to which the purge line can be connected. Furthermore, the purge device can have a metering valve by means of which an amount of the purge gas can be metered. In an advantageous embodiment of the drying system, the drying system can comprise two purge devices, wherein a first purge device can be configured to purge the process chamber with nitrogen and a second purge device can be configured to purge the process chamber with dry air. The purge unit can then comprise two purge lines. Further advantageous embodiments of the drying system emerge from the feature descriptions of the subclaims referring back to method claim 12.

[0027] In the method according to the invention for drying a product, in particular a medical product, electronic product, food product or the like, by means of a drying system, the product is arranged in a process chamber of the drying system, wherein the process chamber and / or the product is heated by means of a heating unit of the drying system, wherein a residual moisture, in particular in the process chamber, is measured by means of a trace moisture measuring device of a moisture measuring unit of the drying system.

[0028] For the advantageous effects of the method according to the invention, reference is made to the description of the advantages of the drying system according to the invention.

[0029] Advantageously, the product can be placed in the process chamber at an ambient temperature. The ambient temperature can then prevail in the process chamber.

[0030] Advantageously, the residual moisture in the process chamber or in the process air contained within the process chamber can be measured. The residual moisture in the process air can be used to determine the residual moisture of the product, or to infer the residual moisture of the product. The residual moisture of the product can therefore be easily determined from the residual moisture in the process chamber or in the process air.

[0031] During heating of the process chamber and / or the product, a vacuum can be created in the process chamber, at least temporarily, to perform vacuum drying. Advantageously, by heating the process chamber and / or the product, the process chamber and / or the product can be heated to a target temperature.

[0032] The residual moisture can be measured during heating of the process chamber and / or the product.

[0033] Advantageously, the residual moisture can be measured or determined at least once after the target temperature has been reached.

[0034] The residual moisture can also be measured at least once after heating the process chamber and / or the product.

[0035] Advantageously, the residual moisture content can be compared with a target moisture content. As soon as the target moisture content is reached or exceeded, the drying process can be terminated. The dried product can then be removed from the process chamber, preferably after the process chamber has cooled down, preferably to ambient temperature.

[0036] Advantageously, the process air present in the process chamber and / or the product can be circulated, at least temporarily, by means of a recirculation unit of the drying system during heating of the process chamber and / or the product in order to achieve uniform heating of the process chamber or the process air and / or the product. The residual moisture can be measured while the recirculation unit is operating in order to obtain a reliable value for the residual moisture.

[0037] Advantageously, the residual moisture of process air or exhaust air discharged from the process chamber during or by circulating the process air in the process chamber can be measured. Advantageously, before heating the process chamber and / or the product, the process chamber can be evacuated by means of an evacuation unit of the drying system and, following the evacuation of the process chamber, the process chamber can be purged with a purge gas, in particular an inert gas, preferably nitrogen or dry air, by means of at least one purge device of a purge unit of the drying system, such that after purging the process chamber with the purge gas, the purge gas can be present in the process chamber. During evacuation, a vacuum can first be formed or built up in the process chamber. A pressure in the process chamber, which can correspond to ambient pressure before evacuation, can then be, for example, < 100 mbar.During evacuation, air or process air with a comparatively high humidity, which may initially be present in the process chamber, for example because ambient air may have flowed into the process chamber as a result of the product being arranged in the process chamber, can be discharged from the process chamber or drying system, for example into an environment. During purging, the vacuum previously built up in the process chamber as a result of evacuating the process chamber can be reduced again. The pressure in the process chamber can then essentially correspond to ambient pressure after purging the process chamber with the purge gas. Since the inert gas is, in particular, free of water vapor, purging or filling the process chamber with the purge gas can initially result in essentially dry process air in the process chamber after purging. In principle, evacuation can also take place without purging and purging can also take place without evacuation.

[0038] Advantageously, the residual moisture can be measured before heating the process chamber and / or the product to determine an initial value. Advantageously, the residual moisture can be measured after evacuating and purging the process chamber with the purge gas to determine the initial value. Advantageously, the heating of the process chamber and / or the product can be carried out after measuring the residual moisture to determine the initial value.

[0039] Advantageously, particularly if the residual moisture content, preferably measured after the target temperature has been reached, is above the target moisture content, the process chamber can be evacuated at least once by means of an evacuation unit of the drying system during heating, preferably at the target temperature, or following heating of the process chamber and / or the product, and following evacuation of the process chamber, the process chamber can be purged with a purge gas, in particular an inert gas, preferably nitrogen or dry air, by means of at least one purge device of a purge unit of the drying system, such that after the process chamber has been purged with the purge gas, the purge gas can be present in the process chamber. The evacuation and subsequent purging can therefore each take place at least once. During the evacuation, a vacuum can first be formed or built up in the process chamber.The pressure in the process chamber, which may correspond to ambient pressure before evacuation, can then be reduced to a target pressure, for example < 100 mbar. As a result of the heating of the process chamber and / or the product, liquid in the product can or could be converted into a gaseous state and increase the humidity or residual moisture of the process air, which may have previously been essentially dry. During evacuation, this process air, which has a comparatively high humidity or residual moisture, can be removed from the process chamber. During purging, the vacuum previously built up in the process chamber as a result of evacuating the process chamber can be reduced again. The pressure in the process chamber can then essentially correspond to ambient pressure after purging the process chamber with the purge gas. Since the inert gas is, in particular, free of water vapor, the purging orFilling the process chamber with purge gas ensures that the process air in the process chamber initially contains essentially dry process air after purging. If evacuation and purging occur during heating, the recirculation unit can be switched off during evacuation and purging and switched on again after evacuation and purging. If evacuation and purging occur after heating, heating can be continued after evacuation and purging, if necessary following a residual moisture measurement. In principle, evacuation can also occur without purging, and purging can also occur without evacuation.

[0040] The residual moisture can be measured following evacuation and rinsing.

[0041] Advantageously, the evacuation of the process chamber and the purging of the process chamber with the purge gas, and if necessary, the continuation of heating, if the evacuation and purging follow heating, can be repeated until the residual moisture reaches or falls below the target moisture level. The residual moisture can thus be successively reduced by running through the above loop until the desired target moisture level is reached.

[0042] The target humidity can, for example, be between 1 ppm and 1000 ppm.

[0043] Further advantageous embodiments of the method emerge from the feature descriptions of the subclaims referring back to device claim 1.

[0044] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings. They show:

[0045] Fig. 1 Schematic diagram of a drying system;

[0046] Fig. 2a Partial schematic diagram of another drying system in an area of ​​a moisture measuring unit of the drying system;

[0047] Fig. 2b Partial schematic diagram of another drying system in an area of ​​a moisture measuring unit of the drying system;

[0048] Fig. 2c Partial schematic diagram of another drying system in an area of ​​a moisture measuring unit of the drying system;

[0049] Fig. 3 Flow chart of a process for drying a product;

[0050] Fig. 4 Diagrammatic representation of residual moisture over time during the implementation of the process.

[0051] Fig. 1 shows a drying system 10, comprising a process chamber 11 in which a product 12 is arranged, and a heating unit designed as a jacket heater for heating the process chamber 11 and the product 12, the heating unit not being shown here. The drying system 10 further comprises a recirculation unit 13 for circulating process air located in the process chamber 11. The recirculation unit 13 comprises a recirculation line 16 connected to an outlet 14 of the drying system 10 and to an inlet 15 of the drying system 10 and a fan 17 integrated into the recirculation line 16, which is configured to circulate the process air in the process chamber 11 via the recirculation line 16 in a flow direction marked by an arrow 18.Furthermore, the drying system 10 comprises a moisture measuring unit 19 integrated into the recirculating air line 16 upstream of the fan 17 in the flow direction, with a trace moisture measuring device 20 arranged in the recirculating air line 16, by means of which a residual moisture of process air discharged from the process chamber 11 via the outlet 14 can be measured. Furthermore, the drying system 10 comprises an evacuation unit 21 for evacuating the process chamber 11. The evacuation unit 21 comprises an evacuation line 22 connected to the recirculation line 16 between the moisture measuring unit 19 or the trace moisture device 20 and the fan 17, and a vacuum pump 23. By means of the vacuum pump 23, process air can be sucked out or discharged from the process chamber 11 in sections via the recirculation line 16 and in a further flow direction marked by an arrow 24 via the evacuation line 22, for example into an environment.In addition, the drying system 10 comprises a purging unit 25 with a first purging device 26 for purging the process chamber 11 with nitrogen and a second purging device 27 for purging the process chamber 11 with dry air. The first purging device 26 or second purging device 27 is connected to the recirculation line 16 via a first purging line 28 of the purging unit 25 or second purging line 29 of the purging unit 25, viewed in the direction of flow, downstream of the fan 17, so that the nitrogen or the dry air can reach the process chamber 11 via the inlet 15. The first purging device 26 or second purging device 27 has a first metering valve 30 or second metering valve 31, respectively.

[0052] Fig. 2a shows a moisture measuring unit 32 of a drying system (not shown in detail here), with a trace moisture measuring device 34 arranged in a recirculation line 33 of a recirculation unit of the drying system (not shown in detail here). The moisture measuring unit 32 corresponds to the moisture measuring unit 19. In this respect, Fig. 2a can be understood as a partial view of Fig. 1 in a region of the moisture measuring unit 19. The drying system can therefore be the drying system 10.

[0053] Fig. 2b shows a moisture measuring unit 35 of a drying system (not shown in detail here), with a bypass line 37 connected to a recirculation line 36 of a recirculation unit (not shown in detail here) of the drying system, in which bypass line 37 a trace moisture measuring device 38 of the moisture measuring unit 35 is arranged. The moisture measuring unit 35 further comprises a measuring gas pump 39 arranged in the bypass line 37 downstream of the trace moisture measuring device 38. The drying system can otherwise be configured like the drying system 10.

[0054] Fig. 2c shows a moisture measuring unit 40 of a drying system (not shown in detail here), with a bypass line 42 connected to a recirculation line 41 of a recirculation unit (not shown in detail here) of the drying system, in which bypass line 42 a trace moisture measuring device 43 of the moisture measuring unit 40 is arranged. The moisture measuring unit 40 further comprises a measuring gas pump 44 arranged in the bypass line 42 downstream of the trace moisture measuring device 43 and a cooling section 45 arranged in the bypass line 42 upstream of the trace moisture measuring device 43. The drying system can otherwise be designed like the drying system 10.

[0055] Fig. 3 shows a flow chart of a method for drying the product 12. The method is carried out using the drying system 10. After a start 46, the product 12 is arranged in the process chamber 11 in a first step 47. The process chamber 11 is then evacuated in a second step 48, preferably to a pressure of < 100 mbar, by means of the evacuation unit 21 and subsequently rinsed to ambient pressure in a third step 49 by means of the purging unit 25. Subsequently, in a fourth step 50, an initial measured value of a residual moisture content in the process chamber 11 is measured or determined by means of the trace moisture measuring device 20. In a fifth step 51, the process chamber 11 and the product 12 are heated to a target temperature by means of the heating unit during operation of the recirculation unit 13.After heating, the process chamber 11 is evacuated to a target pressure in a sixth step 52 by means of the evacuation unit 21 and subsequently purged to ambient pressure in a seventh step 53 by means of the purging unit 25. In an eighth step 54, the residual moisture in the process chamber 11 is measured or determined using the trace moisture measuring device 20 and compared with a target moisture content in a ninth step 55. The fifth step 51, the sixth step 52, the seventh step 53, the eighth step 54, and the ninth step 55 are repeated until the target moisture content is reached or undercut.The sixth step 52, the seventh step 53, the eighth step 54, and the ninth step 55 can also be carried out during heating, in particular while the process chamber and the product have been heated to the target temperature, so that in this case the sixth step 52, the seventh step 53, the eighth step 54, and the ninth step 55 can be repeated until the target moisture content is reached or undershot. The eighth step 54 and the ninth step 55 can also be carried out before the sixth step 52. When the residual moisture content reaches or undershoots the target moisture content, the process chamber 11 can be cooled in a tenth step 56, and the product 12 can be removed or taken out of the process chamber 11 in an eleventh step 57. An end 58 is reached.

[0056] Of course, the procedure can also be used with the ones shown in Fig.

[0057] 2a to 2c. Fig. 4 shows on an ordinate 59 a residual moisture or a moisture content or a saturation of the process air over time on an abscissa 60 during the implementation of the method according to the flow chart shown in Fig. 3. Shown are a first measurement curve 61, a second measurement curve 62 and a third measurement curve 63 for the

[0058] Residual moisture. The measurement curves 61, 62, 63 each initially rise because, as a result of heating, liquid in the product 12, in particular water, is converted into a gaseous state and enters the process air, and then finally reach a substantially constant value (not shown here), running essentially parallel to the abscissa 60. Fig. 4 illustrates how, by repeating in the present example twice, especially the sixth step 52 and the seventh step 53, the residual moisture can be successively reduced until the residual moisture lies below a target moisture level indicated by a straight line 64.

Claims

Patent claims Drying system (10) for drying a product (12), in particular a medical product, electronic product, food product, or the like, comprising a process chamber (11) in which the product can be arranged, and a heating unit for heating the process chamber and / or the product, characterized in that the drying system comprises a moisture measuring unit (19, 32, 35, 40) with a trace moisture measuring device (20, 34, 38, 43) for measuring residual moisture, in particular in the process chamber. Drying system according to claim 1, characterized in that the heating unit is designed as a jacket heater. Drying system according to claim 1 or 2, characterized in that the drying system (10) comprises a recirculation unit (13) for circulating process air located in the process chamber (11). Drying system according to claim 3, characterized in that the drying system (10) comprises an outlet (14) for discharging process air from the process chamber (11) and an inlet (15) for supplying process air into the process chamber, wherein the recirculation unit (13) comprises a recirculation line (16, 33, 36, 41) connected to the outlet and to the inlet, wherein the recirculation unit comprises a circulation device, preferably a fan (17), integrated into the recirculation line, which is designed to circulate the process air via the recirculation line for circulating the process air in the process chamber. Drying system according to claim 4, characterized in that the moisture measuring unit (19, 32, 35, 40) is integrated into the recirculating air line (16, 33, 36, 41) in such a way that the residual moisture of process air discharged from the process chamber (11) can be measured by means of the trace moisture measuring device (20, 34, 38, 43).Drying system according to claim 5, characterized in that the trace moisture measuring device (20, 34) is arranged in the recirculating air line (16, 33). Drying system according to claim 5, characterized in that the moisture measuring unit (35, 40) comprises a bypass line (37, 42) connected to the recirculating air line (36, 41), in which bypass line the trace moisture measuring device (38, 43) is arranged, wherein the moisture measuring unit further comprises a sensor arranged in the bypass line, preferably downstream of the trace moisture measuring device. A measuring gas pump (39, 44) and / or a cooling section (45) arranged in the bypass line, preferably upstream of the trace moisture device. Drying system according to one of the preceding claims, characterized in that the drying system (10) comprises an evacuation unit (21) for evacuating the process chamber (11). Drying system according to claim 8, characterized in that the evacuation unit (21) comprises an evacuation line (22) and an evacuation device, preferably a vacuum pump (23), integrated into the evacuation line. Drying system according to claim 9, characterized in that the drying system (10) comprises a heat exchanger integrated into the evacuation line (22).Drying system according to one of the preceding claims, characterized in that the drying system (10) comprises a purging unit (25) with at least one purging device (26, 27) for purging the process chamber (11) with a purge gas, in particular an inert gas, preferably nitrogen or dry air. A method for drying a product (12), in particular a medical product, electronic product, food product, or the like, by means of a drying system (10), wherein the product is arranged in a process chamber (11) of the drying system, wherein the... Process space and / or the product is heated by means of a heating unit of the drying system, characterized in that a residual moisture, in particular in the process space, is measured by means of a trace moisture measuring device (20, 34, 38, 43) of a moisture measuring unit (19, 32, 35, 40) of the drying system. Method according to claim 12, characterized in that the process space (11) and / or the product (12) is heated to a target temperature, wherein the residual moisture is measured at least once after the target temperature has been reached. Method according to claim 12 or 13, characterized in that at least temporarily during the heating of the process space (11) and / or the product (12) in the process chamber is circulated by means of a recirculation unit (13) of the drying system (10). Method according to claim 14, characterized in that the residual moisture of the process air discharged from the process chamber during the recirculation of the process air in the process chamber (11) is measured. Method according to one of claims 12 to 15, characterized in that before heating the process chamber (11) and / or the product (12) the process space is evacuated by means of an evacuation unit (21) of the drying system (10) and subsequently subjected to the evacuation ieren the process space, the process space is flushed with a flushing gas, in particular inert gas, preferably nitrogen or dry air, by means of at least one flushing device (26, 27) of a flushing unit (25) of the drying system, such that after flushing the process space with the flushing gas, the flushing gas is located in the process space.Method according to one of claims 12 to 16, characterized in that during the heating or subsequent to the heating of the process chamber (11) and / or the product (12), the process chamber is evacuated at least once by means of an evacuation unit (21) of the drying system (10), and following the evacuation of the process chamber, the process chamber is purged with a purge gas, in particular an inert gas, preferably nitrogen or dry air, by means of at least one purge device (26, 27) of a purge unit (25) of the drying system, such that after the purge of the process chamber with the purge gas, the purge gas is present in the process chamber. Method according to claim 17, characterized in that the evacuation of the process chamber (11) and the purge of the process chamber with the purge gas are repeated until the residual moisture content reaches or falls below a target moisture content.

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