Energy-optimized drying system and method for drying a drying medium

Abstract

The invention relates to a drying system (1) for drying a drying medium, having: - an air-air heat exchanger (LLW) (20) which has: - a feed-in LLW exhaust-air flow assembly (100), - a discharge LLW exhaust-air flow assembly (200), - a feed-in LLW fresh-air flow assembly (2000), - a discharge LLW fresh-air flow assembly (3000); - a drying system (30) for drying the drying medium, wherein the fresh air which is heated at least by the air-air heat exchanger (20) and is discharged at least indirectly from the LLW fresh-air flow assembly (3000) interacts, as drying air, with the drying medium, absorbs evaporated moisture from the drying medium, and is dispensed to an exhaust-air line assembly (5000) as moisture-loaded exhaust air (K): - a pre-heating heat exchanger (10) for heating fresh air from an outside temperature (T_A) to the controlled fresh-air inflow temperature (T_G); and - a supply-air line assembly (1000) for feeding the fresh air which at the outside temperature (T_A). The feed-in LLW fresh-air flow assembly (2000) connects the pre-heating heat exchanger (10) to the air-air heat exchanger (20) in order to provide the fresh air at the controlled fresh-air inflow temperature (T_G) to the air-air heat exchanger (20).

Description

[0001] Energy-optimized drying system and drying process for drying a drying medium

[0002] The present invention relates to a drying system for drying a drying medium.

[0003] Furthermore, the present invention relates to a drying method for drying a drying medium using the aforementioned drying system.

[0004] Furthermore, the present invention relates to a drying medium, in particular fiber material, dried by the aforementioned drying process.

[0005] Background of the invention

[0006] It is currently known that waste heat from a fiber drying process, such as paper or cardboard, is generally used to preheat fresh air or drying air. Drying air refers to the air used in the drying process of fiber materials such as paper or cardboard to absorb and remove the moisture contained therein.

[0007] For this purpose, ambient air at an outside temperature is taken from the environment as fresh air and immediately preheated in an air-to-air heat exchanger. Such a heat exchanger is a waste heat utilization system in which fresh air is preheated by warm exhaust air from the drying process to provide drying air. Fresh air is understood to be air taken from the environment, for example from the outside area of ​​a production hall or the production hall itself. Exhaust air is understood to be air that has absorbed moisture through the drying process; it is therefore moisture-enriched drying air. The warm and moisture-enriched exhaust air flows in the air-to-air heat exchanger, for example, through thin-walled smooth tubes. This cools and condenses the exhaust air in the air-to-air heat exchanger.Cold fresh air flows around the thin-walled tubes in the air-to-air heat exchanger, is preheated by the exhaust air, and then flows out of the air-to-air heat exchanger into the further drying process. Air-to-air heat exchangers are available, for example, in cross-flow or cross-counterflow designs, particularly with reversing caps. Plate heat exchangers, for example, made of thin-walled aluminum, stainless steel, glass, or other materials, are also used. It is essential that the exhaust air and fresh air streams are separated from each other.

[0008] It is known and widely established that air-to-air heat exchangers are designed for regional winter temperatures. For Germany, for example, this means that drying systems are dimensioned for operation at an outside hall temperature of minus 15 degrees Celsius. If the outside hall temperature in summer is, for example, 35 degrees Celsius, this corresponds to a temperature gradient of 50 degrees Celsius compared to the dimensioning basis. In summer, this means that air-to-air heat recovery is uneconomical due to the air-to-air heat exchanger being oversized for the summer months, as the drying system is designed for winter operation. The reason for the winter operation design, or winter mode, is that the fresh air should be preheated to the highest possible temperature in the air-to-air heat exchanger even in cold months to ensure smooth operation of the drying system.Due to the low temperatures in winter, an oversized drying system is also essential in the summer months.

[0009] Description of the invention

[0010] Based on this situation, it is an object of the present invention to provide an energy-optimized drying system for year-round operation. This object is achieved by the features of the independent main claims. Advantageous embodiments are specified in the subclaims. Where technically feasible, the teachings of the subclaims can be combined arbitrarily with the teachings of the main and subclaims.

[0011] In particular, the object is achieved by a drying system for drying a drying medium, in particular for drying fibrous materials, the drying system comprising at least the following components: an air-to-air heat exchanger, abbreviated LLW, with an LLW exhaust air volume and an LLW fresh air volume, the air-to-air heat exchanger comprising:

[0012] - an incoming LLW exhaust air flow arrangement for the inflow of exhaust air with an initial temperature into the LLW exhaust air volume and

[0013] - a discharging LLW exhaust air flow arrangement with an exhaust air sequence temperature for the discharge of exhaust air from the LLW exhaust air volume,

[0014] - an incoming LLW fresh air flow arrangement for the inflow of fresh air with a controlled fresh air inflow temperature into the LLW fresh air volume and

[0015] - an outgoing LLW fresh air flow arrangement for the outflow of fresh air with an LLW outlet temperature from the LLW fresh air volume, wherein the LLW exhaust air volume and the LLW fresh air volume are designed such that heat can be transferred from the LLW exhaust air volume to the LLW fresh air volume in order to heat the fresh air; a drying system designed to dry the drying medium, wherein the drying system is designed such that the fresh air, which is heated at least by the air-to-air heat exchanger and at least indirectly flowed out of the LLW fresh air flow arrangement, interacts with the drying medium as drying air and absorbs evaporated moisture from the drying medium and discharges it as moisture-laden exhaust air to an exhaust air duct arrangement;wherein the drying system is designed to guide the exhaust air from the drying system via the exhaust air duct arrangement and via the LLW exhaust air flow arrangement at least indirectly to the air-to-air heat exchanger, so that an at least indirect transfer of heat from the exhaust air in the exhaust air duct arrangement to the fresh air in the air-to-air heat exchanger takes place; wherein the air-to-air heat exchanger energetically reduces the exhaust air from the feeding LLW exhaust air flow arrangement; wherein the drying system has a preheating heat exchanger with a preheating volume and a preheating flow volume, wherein the preheating heat exchanger is designed to heat fresh air, in particular ambient air, from an outside temperature to the regulated fresh air inflow temperature;wherein the drying system comprises a supply air line arrangement for feeding in the fresh air at the outside temperature, wherein the feeding LLW fresh air flow arrangement connects the preheating heat exchanger at least indirectly to the air-to-air heat exchanger in order to provide the fresh air with the regulated fresh air inflow temperature for the air-to-air heat exchanger, in particular for the LLW fresh air volume of the air-to-air heat exchanger;

[0016] Advantageous aspects of the proposed solution are explained below, and further described below are preferred modified embodiments of the proposed solution. Explanations, particularly regarding advantages and definitions of features, are essentially descriptive and preferred, but not limiting, examples. If an explanation is limiting, this will be expressly stated.

[0017] In other words, the preheating heat exchanger is specifically designed to provide a technological solution that allows year-round summer conditions to be simulated in the drying system. The preheating heat exchanger, with the incoming LLW fresh air flow arrangement, can be used to supply a constantly regulated fresh air inlet temperature, for example 35 degrees Celsius. In winter, heating can occur to this regulated fresh air inlet temperature. In summer, the preheating heat exchanger can either be switched off once a certain fresh air temperature has been reached in order to ensure constant operation all year round, or the preheating heat exchanger can regulate the fresh air inlet temperature to a higher level to further increase system efficiency. Annual energy demand is subject to fluctuations in the ambient temperature. These fluctuations also occur throughout the day.For example, during the day, the lowest outside temperature is regularly observed between approximately 4 and 6 a.m. The described invention evens out the temperature fluctuations of the fresh air, particularly the ambient air. This leads, on the one hand, to a more uniform temperature distribution between the incoming LLW exhaust air flow arrangement and the outgoing LLW exhaust air flow arrangement, and, on the other hand, between the incoming LLW fresh air flow arrangement and the outgoing LLW fresh air flow arrangement. Conventional drying systems do not provide such qualitative equalization.

[0018] Compared to conventional air-to-air heat exchangers, the fresh air flowing into the outgoing LLW fresh air flow arrangement can be heated to a higher temperature year-round than is possible with conventional drying systems. At the same time, the exhaust air introduced from the incoming LLW exhaust air flow arrangement and passed through to the outgoing LLW exhaust air flow arrangement is not cooled as much as is typical with a conventional drying system. This keeps the temperature level relatively high compared to a conventional drying system, allowing additional system units to be supplied with a relatively high level of heat.

[0019] In other words, advantages include the fact that the temperature in the outgoing LLW exhaust air flow arrangement always exits the LLW exhaust air volume at a higher temperature level than with conventional drying systems. This occurs while simultaneously maintaining a higher temperature in the outgoing LLW fresh air flow arrangement compared to conventional drying systems. This allows downstream processes, such as downstream heat exchangers, to be supplied with a higher temperature level.

[0020] A key finding is the departure from the established practice of crossing the hottest medium with the coldest medium. This previously led to large temperature gradients, which are now reduced. This allows subsequent heating processes to be supplied with more heat energy, and the existing heat energy can be more effectively utilized. It is important to note that the effect of the invention occurs independently of the specific choice of air-to-air heat exchanger.

[0021] It is generally known that a paper and board machine has an air-to-air heat exchanger. This originated more than 50 years ago. At that time, there were a variety of designs, including different heat exchanger constructions, such as tube or plate heat exchangers. Humid exhaust air was a particular problem. When humid exhaust air comes into contact with cold supply air, the moisture condenses. The resulting corrosion was a significant problem at the time. In addition, the dimensional stability of the connection between any pipes and the walls was compromised. Furthermore, short circuits or contact between the exhaust air and supply air were prevented, as the drier supply air would be contaminated with moister exhaust air. To solve these problems, the company "Langbein & Engelbracht" developed a glass tube heat exchanger.The great advantage of this invention was that glass was chosen as a material that was dimensionally stable against acids, alkalis, water, oil, etc. Furthermore, the corrosiveness of water was no longer a major problem. Over the years, various air-to-air heat exchangers have become established.

[0022] The integration of a preheating heat exchanger into a drying system has so far been out of the question due to its production costs and the space it requires. However, current developments have shown that the increased efficiency provided by the preheating heat exchanger enables significantly more efficient operation of the drying system, thus amortizing the costs of purchasing and operating the preheating heat exchanger. In other words, it shows that the efficiency of the entire drying system is increased on an annual average, both in summer and winter. All flow or piping arrangements are not to be understood as pipes in the limit, but can represent any material flow volume. However, pipes and / or ducts are also possible.

[0023] Where water is mentioned below, this medium can also be a replacement or supplementary medium with a similar function and effect. For example, the water for the air-water heat exchanger can be a water-glycol mixture. Media with other freezing-point-lowering properties, such as salt, oil, or other media, are also possible. This is partly implied by the phrase "essentially water."

[0024] Preheating is not limited to one preheating heat exchanger; two or more different heat exchange systems can also be used.

[0025] Aspects of the drying system are discussed further below.

[0026] The drying system is in particular a fiber drying system, particularly preferably a paper and / or cardboard drying system.

[0027] The drying system features an air-to-air heat exchanger, abbreviated LLW, with an LLW exhaust air volume and an LLW fresh air volume. The air-to-air heat exchanger can be, for example, a tube or plate heat exchanger, but is not limited to this type.

[0028] As mentioned above, tube heat exchangers and plate heat exchangers are specific types of heat exchangers used to transfer thermal energy from one medium to another. However, they differ in their design and operation.

[0029] An exemplary and non-limiting tube heat exchanger consists of a pipe system in which a warm medium, for example, air, flows in the inner pipe and a cool medium, for example, air, flows in the outer pipe. The pipes, or the cold-hot configuration, can in principle be interchanged. It is also generally possible to use another medium, for example, primarily water, instead of air.

[0030] In particular, the media flow in opposite directions, whereby the hot medium in the inner pipe heats the cooler medium in the outer pipe.

[0031] Tube heat exchangers are often installed in heating systems and heat the medium in the heat storage tank. Tube heat exchangers are relatively easy to clean and descale. If the exhaust air is routed through an inner tube, this can be cleaned using a cleaning projectile that is subjected to compressed air and / or a liquid, especially water. The supply air around the outer tube is regularly filtered, so cleaning processes are not necessary at this point.

[0032] An exemplary and non-limiting plate heat exchanger consists of wave-shaped profiled plates which are assembled in such a way that the medium to be heated and then the heat-emitting medium flows in the successive spaces.

[0033] Plate heat exchangers are very flexible in terms of flow design and can be built very compactly and have a high heat flux density.

[0034] Plate heat exchangers must be cleaned if they become dirty or calcified. Bolted plate heat exchangers can be disassembled into their individual components for cleaning, while brazed plate heat exchangers must be replaced.

[0035] Both types of heat exchangers are used to transfer heat energy from one medium to another.

[0036] Tube heat exchangers, for example and not limited to glass tube heat exchangers, utilize a system of tubes for heat exchange, while plate heat exchangers utilize corrugated plates. Plate heat exchangers can be constructed more compactly and have a higher heat flux density than tube heat exchangers. However, large plate heat exchangers have the disadvantage of increasing laminar heat transfer with increasing distance, whereas in tube heat exchangers, the tubes repeatedly break the flowing medium, enabling or promoting turbulent flow.

[0037] However, cleaning a tube heat exchanger is easier than cleaning a plate heat exchanger, especially if it's a brazed plate heat exchanger. Therefore, the heat exchanger is selected based on requirements.

[0038] If a heat exchanger is referred to here, other heat exchanger systems can be used in addition to tube heat exchangers and plate heat exchangers.

[0039] The air-to-air heat exchanger has an incoming LLW exhaust air flow arrangement for the inflow of exhaust air with an initial temperature into the LLW exhaust air volume.

[0040] The exhaust air is, by way of example and not limitation, air that has already been part of a drying process and, consequently, has a higher humidity than fresh air, especially ambient air. The initial temperature can be, by way of example and not limitation, 85 degrees Celsius.

[0041] The air-to-air heat exchanger further comprises a discharging LLW exhaust air flow arrangement with an exhaust air follow-up temperature for the outflow of exhaust air from the LLW exhaust air volume.

[0042] The air-to-air heat exchanger further comprises an incoming LLW fresh air flow arrangement for supplying fresh air with a regulated fresh air inflow temperature into the LLW fresh air volume. Fresh air is, by way of example and not by way of limitation, air that has not yet been a specific component of a system-internal drying process. Ambient air is preferably considered fresh air. The fresh air particularly preferably has a lower humidity than the exhaust air.

[0043] The air-to-air heat exchanger further comprises an outgoing LLW fresh air flow arrangement for discharging fresh air with an LLW outlet temperature from the LLW fresh air volume.

[0044] The LLW exhaust air volume and the LLW fresh air volume are designed in such a way that heat can be transferred from the LLW exhaust air volume to the LLW fresh air volume to heat the fresh air. The thus heated fresh air is or can be used in a later process step to dry the drying medium.

[0045] The LLW outlet temperature can be, for example and not limited to, 65 degrees Celsius.

[0046] The drying system can, in particular, operate without compressing the exhaust air, with at least the air-to-air heat exchanger (LLW) preferably operating without compressing the exhaust air. Heat transfer can, for example, occur directly from the moist exhaust air to the fresh air, without the exhaust air being compressed beforehand.

[0047] The drying system further comprises a drying system designed to dry the drying medium using the heated fresh air. The drying system is configured such that the fresh air, which is heated at least by the air-to-air heat exchanger and at least indirectly discharged from the LLW fresh air flow arrangement, interacts with the drying medium as drying air. During this interaction, moisture is absorbed from the drying medium and discharged as moisture-laden exhaust air to an exhaust air duct arrangement. The temperature in the exhaust air duct arrangement preferably corresponds at least to the initial temperature. The exhaust air from the exhaust air duct arrangement is preferably passed directly into the LLW exhaust air flow arrangement, so that essentially a similar temperature, namely the initial temperature, prevails in both arrangements.However, it is also possible that one or more heat exchangers are interposed between the exhaust air duct arrangement and the subsequent LLW exhaust air flow arrangement, so that, for example, the temperature at the exhaust air duct arrangement is higher than the initial temperature.

[0048] Thus, the drying system is designed to guide the exhaust air from the drying system via the exhaust air duct arrangement and subsequently via the LLW exhaust air flow arrangement at least indirectly to the air-to-air heat exchanger, so that an at least indirect transfer of the heat from the exhaust air in the exhaust air duct arrangement to the fresh air in the air-to-air heat exchanger takes place.

[0049] As a result, the air-to-air heat exchanger reduces the energy consumption of the exhaust air from the incoming LLW exhaust air flow arrangement. This means that heat energy from the exhaust air is transferred from the LLW exhaust air volume to the fresh air in the LLW fresh air volume.

[0050] The drying system further comprises a preheating heat exchanger with a preheating volume and a preheating flow volume. The preheating heat exchanger is designed to heat the fresh air, in particular the ambient air, from an outside temperature to the regulated fresh air inlet temperature. The preheating heat exchanger thus serves as a means for regulating the regulated fresh air inlet temperature.

[0051] The outside temperature can, for example and without limitation, be minus 20 degrees Celsius in winter and 35 degrees Celsius in summer. This cannot generally be influenced, as ambient air is regularly fed in, which sometimes has different temperatures depending on the season. Thus, the outside temperature is, for example and without limitation, a temperature outside the drying system, in particular a not significantly heated hall temperature and / or an outside hall temperature. The drying system further comprises an air supply duct arrangement for feeding in fresh air at the outside temperature. The fresh air is preferably fed into the preheating heat exchanger, particularly preferably into the preheating volume of the preheating heat exchanger.

[0052] The feeding LLW fresh air flow arrangement connects the preheating heat exchanger at least indirectly with the air-to-air heat exchanger in order to provide the fresh air with the regulated fresh air inflow temperature for the air-to-air heat exchanger, in particular for the LLW fresh air volume of the air-to-air heat exchanger.

[0053] The regulated fresh air inlet temperature can be, for example, and not limited to, 35 degrees Celsius.

[0054] Since in conventional drying systems, the hottest air within the drying system, namely the exhaust air from the completed drying process, from the incoming LLW exhaust air flow arrangement encounters the coldest air, namely the fresh air, especially ambient air, the high temperature level of the exhaust air is already fully utilized in the air-to-air heat exchanger, which means that the achievable LLW outlet temperature is physically limited compared to the invention. The resulting LLW outlet temperature is thus essentially an average temperature of the initial temperature and the unregulated fresh air inlet temperature. This means that the LLW outlet temperature is highly dependent on the time of year or on the outside temperature of the required fresh air.

[0055] This means, for example (and not limitingly), that in a conventional drying system in winter, with an outside fresh air temperature of minus 20 degrees Celsius and an initial exhaust air temperature of 85 degrees Celsius, the LLW outlet temperature of the warmed fresh air available for drying the fiber is approximately only 45 degrees Celsius. With a required fresh air drying temperature of approximately 85 degrees Celsius in the drying system, the heat difference of 40 degrees Celsius must be compensated for in a later process step, but upstream of the drying system, using one or more additional heat exchangers. This represents a very energy-intensive process step and generally requires additional heat input from higher-calorific energy sources, such as gas burners.This process reduces the initial exhaust air temperature from 85 degrees Celsius to 55 degrees Celsius, so that the subsequent exhaust air temperature usable in subsequent process steps is essentially limited to a maximum of 55 degrees Celsius. This example mode is referred to as winter mode.

[0056] If, in the same conventional drying system, the outside fresh air temperature is 35 degrees Celsius and the initial exhaust air temperature is 85 degrees Celsius in summer, the LLW outlet temperature of the warmed fresh air available for drying the fiber, for example, is approximately 65 degrees Celsius. If the required fresh air drying temperature in the drying system is approximately 85 degrees Celsius, the heat difference of 20 degrees Celsius must be compensated for in a later process step, but upstream of the drying system, using one or more additional heat exchangers. This represents a less energy-intensive process step than in winter mode and generally requires additional heat input from higher-calorific energy sources, such as gas burners.This process reduces the initial exhaust air temperature from 85 degrees Celsius to 70 degrees Celsius, so that the subsequent exhaust air temperature usable in subsequent process steps is essentially limited to a maximum of 70 degrees Celsius. This example mode is referred to as summer mode.

[0057] The aforementioned conventional drying system therefore has the disadvantage that the usable fresh air outlet temperature and the usable exhaust air follow-up temperature depend significantly on the outside temperature. To ensure that the drying system can operate flawlessly all year round, the drying system must therefore be dimensioned for winter operation, which results in considerable production and operating costs for the higher-calorific energy sources. Only the present solution enables the simulation or imitation of a continuous summer mode, using a controlled fresh air inlet temperature, so that winter temperatures are no longer important for system dimensioning. It is worth mentioning that the energy introduced in the preheating heat exchanger is used to increase the fresh air temperature from the outside temperature to the controlled fresh air inlet temperature at a low temperature.This has the advantage that a temperature level that is unused in conventional drying systems is used, so that the overall efficiency of the drying system is increased with regard to the usable exhaust air temperature of the exhaust air.

[0058] Since the regulated fresh air inlet temperature is higher even in winter than in conventional drying systems, the exhaust air follow-up temperature in the proposed solution is similar to the summer mode year-round, enabling year-round use of the exhaust air at the exhaust air follow-up temperature for the first time. Due to the constantly simulated summer mode and the associated higher temperature level compared to winter mode, the overall efficiency of the drying system is increased compared to conventional drying systems. The medium conveyed in the outgoing LLW exhaust air flow arrangement, with the constantly higher exhaust air follow-up temperature compared to winter mode, enables higher-calorific downstream systems to be operated, which would otherwise not be possible at the same temperature level in winter.

[0059] In other words, in conventional drying systems without preheating heat exchangers, a heat exchanger was installed downstream of the outgoing LLW fresh air flow arrangement in winter mode to achieve the desired LLW outlet temperature of the conveyed medium. A heat exchanger was installed downstream of the outgoing LLW exhaust air flow arrangement if the exhaust air temperature present in winter mode was insufficient for subsequent processes. The proposed solution thus eliminates an entire heat stage in the sense of reheating by integrating the preheating heat exchanger.

[0060] If the terms are used in a calorific sense, especially low- or high-calorie, then all heat in the medium that is less than the media heat in the outgoing LLW exhaust air flow arrangement is considered low-calorie. Accordingly, all heat in the medium that is greater than the media heat in the outgoing LLW exhaust air flow arrangement is considered high-calorie. Similarly, temperatures can also be used as a reference value, in which case the exhaust air temperature in the outgoing LLW exhaust air flow arrangement is considered the transition from low- to high-calorie.

[0061] In particular, this enables direct or indirect low-temperature waste heat utilization as a precursor to air-to-air heat recovery. The waste heat from the actual drying process or from other processes can be utilized. Furthermore, an optimized, year-round design of air-to-air heat recovery based on climatic summer temperature values ​​is proposed.

[0062] One preferred aspect also concerns the use of the preheating solution as an "anti-icing substitute" in cold climates. In particular, a portion of the already preheated supply air is remixed with the intake air. This prevents the previously problematic freezing during air-to-air heat recovery. It is also possible to preheat the system to ambient safe temperatures using a suitable heat transfer medium.

[0063] Compared to a conventional air-to-air heat recovery system, the energy yield is up to 30 percent higher with the same energy input, resulting in increased performance.

[0064] This type of application can be retrofitted to any heat recovery system. The proposed solution has been shown to meet the current goal of reducing primary energy consumption. After all, high utilization of exhaust air energy throughout the year is effective, both in reducing primary energy consumption and in reducing CO2 emissions.

[0065] According to a modified embodiment, the drying system comprises at least one media heat exchanger configured to be supplied with a medium to adjust the fresh air from the outgoing LLW fresh air flow arrangement to a predefined process temperature, which is supplied to the drying system via a flow-through arrangement included in the drying system. The multi-stage design allows the predefined process temperature, for example, the drying temperature, to be adjusted more precisely.

[0066] Preferably, the predefined process temperature is between at least 80 and at most 120 degrees Celsius.

[0067] According to a modified embodiment, the media heat exchanger is designed to be supplied with fresh steam, oil, hot water, brine, hydrogen, district heating, electricity, gas combustion, and / or a mixture thereof to adjust the fresh air to the predefined process temperature. It has been found that the above energy sources enable reliable operation of the media heat exchanger.

[0068] According to a modified embodiment, the media heat exchanger comprises one or more waste heat exchangers between the air-to-air heat exchanger and the drying system, wherein the waste heat exchanger(s) of the media heat exchanger at least indirectly utilize(s) heat from a self-contained steam-condensate system designed to dry the drying medium in the drying system, in order to heat the fresh air of the LLW fresh air flow arrangement to the predefined process temperature and to pass it on to the drying system by means of the flow-through arrangement. A steam-condensate system is a technical system that utilizes steam that would otherwise escape unused into the environment. It is thus a self-contained system for providing the heat from the steam for drying in an energy-efficient manner.This has been shown to enable reliable operation of the media heat exchanger and provide a system-efficient design. The fresh air can preferably be heated using waste heat from the overall process, but can also be heated in isolation or additionally by the steam-condensate system.

[0069] According to a modified embodiment, it is provided that the drying system has an air-water heat exchanger, abbreviated LWW, with an LWW transfer volume and an LWW heating volume, wherein the air-water heat exchanger is designed to heat a first liquid and / or gaseous flow heat medium, in particular substantially water, in the LWW heating volume from heat from the LWW transfer volume to the LWW heating volume, wherein the drying system further comprises a flow heat arrangement which is designed to forward the first flow heat medium from the LWW heating volume.

[0070] In particular, and not necessarily related to the above feature set, the drying system further comprises a heat feed arrangement configured to feed the first and / or multiple flow heat media into the preheating flow volume. This allows heat to be extracted from the process and returned to the drying system, resulting in an increase in efficiency. This allows low-temperature energy to be utilized that was previously dissipated unused. This is therefore an efficient method for simulating a summer mode of the drying system year-round.

[0071] The wording that the fluid heat medium can essentially be water, for example, means that it is a frost-resistant medium. Therefore, the addition of the wording "essentially" implies that an antifreeze is added to the water. If the solution also proposes essentially water in other places, a similar approach should be chosen. If the wording "fluid heat medium" is used, it is preferable that it be frost-resistant. If the solution also proposes a fluid heat medium in other places, a similar approach should be chosen.

[0072] If several flow heat media are used that are fed into the preheating flow volume, these can come from various sources and are not limited to the air-water heat exchanger.

[0073] According to a modified embodiment, the first flow heat medium flows at least indirectly from the flow heat arrangement into the heat feed arrangement for at least indirect regulation of the fresh air inflow temperature, and / or wherein the flow heat arrangement connects the air-water heat exchanger at least indirectly to the preheating heat exchanger in order to transfer the heated flow heat medium from the air-water heating volume of the air-water heat exchanger to the preheating heat exchanger for at least indirect regulation of the fresh air inflow temperature. This utilizes heat in the low-calorific range that would otherwise be dissipated.

[0074] The phrase "at least indirectly" means that a fundamental functional connection exists, even if additional structural components may be interposed. For example, heat from the first flow heat medium is transferred to the fresh air, which represents at least an indirect heat transfer. If the solution also proposes the phrase "at least indirectly" in other places, a similar approach should be chosen.

[0075] According to a modified embodiment, the air-water heat exchanger is a low-temperature air-water heat exchanger, wherein the flow heat medium is a low-temperature heat medium with a low temperature, and wherein the flow heat arrangement is a low-temperature heat pipe, wherein the low temperature of the flow heat medium, starting from the air-water warm-up volume, is greater than the outside temperature in the supply air pipe arrangement. This optimizes the use of a permanent, i.e., year-round, summer mode.

[0076] If the term "low temperature" is used, the low temperature is defined as the media temperature that is lower than the exhaust air temperature in the outgoing LLW exhaust air flow arrangement. Accordingly, the high temperature is defined as any media temperature that is higher than the exhaust air temperature in the outgoing LLW exhaust air flow arrangement.

[0077] The outside temperature is the temperature of the fresh air fed into the supply air duct arrangement.

[0078] According to a modified embodiment, the drying system (1) comprises a heat feed arrangement, in particular the heat feed arrangement according to one of claims 5 to 7, which is designed to feed a first or more flow heat media with a preheat inflow temperature into the preheat flow volume, wherein the preheat inflow temperature is lower than the initial temperature. This optimizes the use of a permanent, i.e. year-round, usable summer mode.

[0079] Where temperatures are mentioned, they apply to the respective media temperature. This applies to all temperatures.

[0080] According to a modified embodiment, the drying system comprises one or more heat exchanger devices between the air-to-air heat exchanger and the air-to-water heat exchanger, wherein the heat exchanger device(s) utilize(s) heat from the exhaust air in the outgoing LLW exhaust air flow arrangement to heat a medium, preferably a liquid medium, particularly preferably essentially water. This optimizes the use of a permanent, year-round, summer mode. For example, this also allows for media heating in winter, the heat from which can be used for subsequent processes.

[0081] According to a modified embodiment, it is provided that a gas medium, in particular essentially combustion gas, is used as a carrier medium for drying the drying medium in the drying plant.

[0082] According to a modified embodiment, an existing drying system with at least one aforementioned air-to-air heat exchanger and an aforementioned drying system is retrofitted to a proposed drying system. This means that conventional drying systems can be optimized at any time to operate year-round in summer mode, thus improving overall efficiency, without having to completely demolish and rebuild the drying system. In particular, the preheating heat exchanger can be retrofitted with the connecting components to the drying system.

[0083] According to a modified embodiment, it is provided that the drying system is designed such that the fresh air in the feeding LLW fresh air flow arrangement with the regulated fresh air inflow temperature at least indirectly, in particular directly, thermally influences the LLW outlet temperature in the feeding LLW fresh air flow arrangement, wherein in particular an increasing fresh air inflow temperature brings about an increasing outlet temperature and an increasing exhaust air follow-up temperature and a decreasing fresh air inflow temperature brings about a decreasing LLW outlet temperature and a decreasing exhaust air follow-up temperature.Compared to conventional air-to-air heat exchangers, the fresh air can be heated to a higher temperature than is the case with conventional drying systems, and the exhaust air from the incoming LLW exhaust air flow arrangement to the outgoing LLW exhaust air flow arrangement is not cooled as much as, for example, with a classic counterflow heat exchanger. As a result, the temperature level at the outlet of the air-to-air heat exchanger remains less reduced than in the prior art, and further processes with high calorific values ​​and temperature gradients can be supplied. Further provided is a drying method for drying a drying medium using the aforementioned drying system, the drying method comprising at least the following step:

[0084] Heating the fresh air in the preheating heat exchanger, especially in the preheating volume, from the outside temperature to the controlled fresh air inlet temperature. The above advantages apply equally here.

[0085] According to a modified embodiment, it is provided that the heating of the fresh air in the preheating heat exchanger, in particular in the preheating volume, takes place under the influence of the first and / or several flow heat media fed from the aforementioned heat feed arrangement into the preheating flow volume.

[0086] Any feature described for an embodiment of the drying system claim category can also be used correspondingly in the drying method claim category. It is preferred that the sequence of method steps can be varied, unless technically required in an explicit order.

[0087] Further provided is a drying medium, in particular a fibrous material, dried by an above drying method.

[0088] The following is an exemplary and non-limiting example of the drying system, whereby individual system units, as explained below, do not necessarily have to be part of the drying system. Thus, as already mentioned, the following example of the drying system is not limiting in nature. In particular, the features can be excluded or combined with one another according to the teachings of the individual claims from the following explanation. The drying system comprises in particular the preheating heat exchanger, the air-to-air heat exchanger and the drying system. Optionally and non-bindingly, the heat exchanger device with the described features can be integrated into the drying system. Furthermore, optionally and non-bindingly, the air-to-water TI

[0089] Heat exchangers with the described features can be integrated into the drying system. The media heat exchanger with the described features can also be integrated into the drying system optionally and not mandatory. It is possible to include only the heat exchanger device, only the air-water heat exchanger, or only the media heat exchanger. However, permutations of heat exchanger device, air-water heat exchanger, and media heat exchanger are also possible. For example, heat exchanger device and air-water heat exchanger, media heat exchanger and air-water heat exchanger, or even heat exchanger device and media heat exchanger. All three system devices can also be present.

[0090] The fresh air flows, in particular, via the supply air duct arrangement into the preheating heat exchanger, in particular into its preheating volume, and leaves the preheating heat exchanger via the incoming LLW fresh air flow arrangement. Likewise, in particular, a first flow heat medium, in particular essentially water, and optionally further flow heat media flow into the preheating heat exchanger, in particular into the preheating flow volume, and then leaves the preheating heat exchanger. The fresh air flowing into the preheating volume has, in particular with its outside temperature, a lower temperature than the first or further flow heat media at the preheating inflow temperature, so that the fresh air subsequently has a regulated fresh air inflow temperature, i.e., a temperature adjusted as desired by heat transfer.

[0091] The preheating heat exchanger is operatively connected, in particular, to the air-to-air heat exchanger. The air-to-air heat exchanger has an air-to-air exhaust air volume. The air-to-air exhaust air volume takes in air, preferably moisture-laden exhaust air, particularly preferably moisture-laden exhaust air from the drying process in the drying system, at an initial temperature via an incoming air-to-air exhaust air flow arrangement and discharges this air via the outgoing air-to-air exhaust air flow arrangement at the subsequent exhaust air temperature. The air-to-air heat exchanger also has an air-to-air fresh air volume. The air-to-air fresh air volume takes in the fresh air from the incoming air-to-air fresh air flow arrangement at the regulated fresh air inlet temperature and discharges this fresh air to the outgoing air-to-air fresh air flow arrangement at the outlet temperature.

[0092] The fresh air flowing from the preheating heat exchanger via the incoming LLW fresh air flow arrangement into the air-to-air heat exchanger, in particular into the LLW fresh air volume, has a lower temperature than the air at the initial temperature from the incoming LLW exhaust air flow arrangement. However, the fresh air flowing via the incoming LLW fresh air flow arrangement into the air-to-air heat exchanger, in particular into the LLW fresh air volume, with its regulated fresh air inflow temperature, has a higher temperature than the ambient air. This results in the LLW outlet temperature being higher than if the fresh air had flowed into the LLW fresh air volume at the ambient temperature.This also means that the temperature in the LLW exhaust air volume does not drop as in conventional drying systems, so that the air in the outgoing LLW exhaust air flow arrangement with the exhaust air subsequent temperature, unlike in conventional drying systems, is of high interest and usable for subsequent processes.

[0093] Regardless of the other features, the fresh air is designed to flow at the LLW outlet temperature via the outgoing LLW fresh air flow arrangement into the media heat exchanger. Various heat transfer processes can take place in this media heat exchanger, so that the fresh air then flows out of the media heat exchanger at a predefined process temperature and along the flow arrangement into the drying system. If no media heat exchanger is provided, the LLW outlet temperature can also directly correspond to the predefined process temperature.

[0094] Coming from the flow-through arrangement, or if no media heat exchanger is present, from the outgoing LLW fresh air flow arrangement, the fresh air flows into the drying system for the drying process of the drying medium. After the drying process of the drying medium, it flows from there into the exhaust air duct arrangement. The fresh air then becomes moisture-laden exhaust air. The moisture in the exhaust air originates from the dried drying medium.

[0095] This moisture-laden exhaust air can be fed directly or indirectly, for example after further heat transfer processes, into the air-to-air heat exchanger via the incoming LLW exhaust air flow arrangement at the temperature which is referred to as the initial temperature from the process step onwards.

[0096] The air flowing from the air-to-air heat exchanger along the outgoing LLW exhaust air flow arrangement can flow via the heat exchanger device, interacting with a liquid medium for heat transfer, along one or more fluid lines to the air-to-water heat exchanger. Optionally, the exhaust air flowing from the air-to-air heat exchanger along the outgoing LLW exhaust air flow arrangement can also flow directly to the air-to-water heat exchanger.

[0097] The air-water heat exchanger has, in particular, an air-water transfer volume and an air-water heating volume. In the air-water heat exchanger, the exhaust air flows through, in particular, an air-water transfer volume and exchanges heat with a first flow heat medium flowing through the air-water heating volume.

[0098] The first flow heat medium and / or additional flow heat media can then flow out of the LWW heating volume through a flow heat arrangement into a heat feed arrangement, which in turn flows into the preheat flow volume of the preheating heat exchanger for heat exchange. Following this cycle, residual heat from the preheating heat exchanger is returned to the preheating heat exchanger.

[0099] Short description of the drawing

[0100] The invention will be explained in more detail below with reference to the accompanying drawings using preferred embodiments. The drawing shows

[0101] Figure 1 is a diagram of a drying system according to a preferred embodiment of the invention.

[0102] Detailed description of an embodiment

[0103] The described embodiment is to be understood merely as an example that can be modified and / or supplemented in a variety of ways within the scope of the claims. Each described feature can be used independently or in combination with other features in any other embodiment.

[0104] Any feature described for an embodiment of the claim category of a drying system can also be used in a corresponding manner in the claim category of a drying method.

[0105] Figure 1 shows a drying system 1 for drying a drying medium. The drying of the drying medium is particularly a drying of fibrous materials, for example and not limited to paper or cardboard.

[0106] The drying system 1 shown in Figure 1 comprises, according to a preferred embodiment, the components described below.

[0107] The arrows shown in Figure 1, particularly the arrangements with the reference numerals 100, 200, 300, 400, 500, 1000, 2000, 3000, 4000, and 5000, are schematic representations of media-carrying flow systems, particularly pipes or ducts, with the flow direction shown. Constant media have constant hatching in the arrows. It should be clarified that Figure 1 is a schematic diagram that is not limited to cocurrent or cross-countercurrent heat transfer. In principle, both heat transfer options are covered by the scope of protection.

[0108] The drying system 1 has an air-to-air heat exchanger, abbreviated LLW, 20 with an LLW exhaust air volume 21 and an LLW fresh air volume 22. The air-to-air heat exchanger LLW 20 is, for example, a tube or plate heat exchanger.

[0109] The air-to-air heat exchanger 20 has an incoming LLW exhaust air flow arrangement 100 for the inflow of exhaust air K with an initial temperature TI into the LLW exhaust air volume 21.

[0110] The exhaust air K is, by way of example and not limitation, air that has already been part of a drying process and, consequently, has a higher humidity than fresh air, especially ambient air. The initial temperature TI can be, by way of example and not limitation, 85 degrees Celsius.

[0111] The air-to-air heat exchanger 20 further comprises a discharging LLW exhaust air flow arrangement 200 exhaust air sequence temperature T_AF for the outflow of exhaust air K from the LLW exhaust air volume 21.

[0112] The air-to-air heat exchanger 20 further comprises an incoming LLW fresh air flow arrangement 2000 for the inflow of fresh air with a regulated fresh air inflow temperature T_G into the LLW fresh air volume 22.

[0113] Fresh air is, by way of example and not limitation, air that has not yet been an internal component of a drying process. Ambient air is preferably considered fresh air. Fresh air is particularly preferably lower in humidity than the exhaust air K.

[0114] The air-to-air heat exchanger 20 further comprises an outgoing LLW fresh air flow arrangement 3000 for the outflow of fresh air with an LLW outlet temperature T AT from the LLW fresh air volume 22. The LLW exhaust air volume 21 and the LLW fresh air volume 22 are designed such that heat can be transferred from the LLW exhaust air volume 21 to the LLW fresh air volume 22 in order to heat the fresh air.

[0115] The outlet temperature T AT can be, for example and not limited to, 67 degrees Celsius.

[0116] The drying system 1 further comprises a drying system 30 designed to dry the drying medium. The drying system 30 is designed such that the fresh air, which is heated at least by the air-to-air heat exchanger 20 and at least indirectly discharged from the LLW fresh air flow arrangement 3000, interacts with the drying medium as drying air. In the process, evaporated moisture is absorbed from the drying medium and discharged as moisture-laden exhaust air K to an exhaust air duct arrangement 5000. The temperature in the exhaust air duct arrangement 5000 preferably corresponds at least to the initial temperature TI. The exhaust air K from the exhaust air duct arrangement 5000 is preferably passed directly into the LLW exhaust air flow arrangement 100, so that essentially a similar temperature, namely the initial temperature TI, prevails in both arrangements 100, 5000.However, it is also possible that one or more heat exchangers are interposed between the exhaust air duct arrangement 5000 and the subsequent LLW exhaust air flow arrangement 100, so that the temperature at the exhaust air duct arrangement 5000 is greater than the initial temperature T I.

[0117] Thus, the drying system 1 is designed to guide the exhaust air K from the drying system 30 via the exhaust air duct arrangement 5000 and subsequently via the LLW exhaust air flow arrangement 100 at least indirectly to the air-to-air heat exchanger 20, so that an at least indirect transfer of the heat from the exhaust air K in the exhaust air duct arrangement 5000 to the fresh air in the air-to-air heat exchanger 20 takes place.

[0118] As a result, the air-to-air heat exchanger 20 reduces the energy of the exhaust air K from the incoming LLW exhaust air flow arrangement 100. This means that heat energy from the exhaust air K is transferred from the LLW exhaust air volume 21 to the fresh air in the LLW fresh air volume 22.

[0119] The drying system 1 further comprises a preheating heat exchanger 10 with a preheating volume 11 and a preheating flow volume 12, wherein the preheating heat exchanger 10 is designed to heat the fresh air, in particular the ambient air, from an outside temperature TA to the controlled fresh air inflow temperature T_G.

[0120] The outside temperature TA can, for example, be minus 20 degrees Celsius and not limited to this.

[0121] The drying system 1 further comprises an air supply line arrangement 1000 for feeding in fresh air with the outside temperature T A.

[0122] The feeding LLW fresh air flow arrangement 2000 connects the preheating heat exchanger 10 at least indirectly to the air-to-air heat exchanger 20 in order to provide the fresh air with the regulated fresh air inflow temperature T_G for the air-to-air heat exchanger 20, in particular for the LLW fresh air volume 22 of the air-to-air heat exchanger 20.

[0123] The controlled fresh air inlet temperature T_G can be, for example and not limited to, 35 degrees Celsius.

[0124] The exhaust air temperature T AF can, for example, be 70 degrees Celsius, but is not limited to this.

[0125] The drying system 1 has at least one media heat exchanger 40, which is designed to be supplied with a medium in order to adjust the fresh air from the outgoing LLW fresh air flow arrangement 3000 to a predefined process temperature TP. The fresh air adjusted to the predefined process temperature TP is supplied to the drying system 30 via a flow arrangement 4000 included in the drying system 1. The media heat exchanger 40 is designed to be supplied with fresh steam, oil, hot water, brine, hydrogen, district heating, electricity, gas combustion, and / or a mixture thereof in order to adjust the fresh air to the predefined process temperature TP.

[0126] Furthermore, it is provided that the media heat exchanger 40 has one or more waste heat exchangers between the air-to-air heat exchanger 20 and the drying system 30. In this case, one or more waste heat exchangers of the media heat exchanger 40 at least indirectly utilize heat from a self-sufficient steam condensate system, which is designed to dry the drying medium in the drying system 30, in order to heat the fresh air of the LLW fresh air flow arrangement 3000 to the predefined process temperature TP and to pass it on to the drying system 30 by means of the flow arrangement 4000.

[0127] The drying system 1 shown in Figure 1 comprises an air-water heat exchanger, abbreviated LWW, 60 with an LWW transfer volume 61 and an LWW heating volume 62. The air-water heat exchanger 60 is designed to heat a first liquid and / or gaseous flow heat medium S, in particular essentially water, in the LWW heating volume 62 from heat from the LWW transfer volume 61 to the LWW heating volume 62.

[0128] The drying system 1 further comprises a flow heat arrangement 400 which is designed to forward the first flow heat medium S from the LWW heating volume 62.

[0129] In particular, the drying system 1 further comprises a heat feed arrangement 500 which is designed to feed the first and / or several flow heat media S, X into the preheating flow volume 12.

[0130] Preferably, the first flow heat medium S flows at least indirectly from the flow heat arrangement 400 into the heat feed arrangement 500 for at least indirect regulation of the fresh air inflow temperature T_G. Alternatively or additionally, the flow heat arrangement 400 connects the air-water heat exchanger 60 at least indirectly, by way of example and independently of the other associated features, via the heat feed arrangement 500, to the preheating heat exchanger 10 in order to pass the heated flow heat medium S from the air-water heating volume 62 of the air-water heat exchanger 60 into the preheating heat exchanger 10 for at least indirect regulation of the fresh air inflow temperature T_G.

[0131] Preferably, the air-water heat exchanger 60 is a low-temperature air-water heat exchanger. In this case, the flow heat medium S is a low-temperature heat medium with a low temperature TN, and the flow heat arrangement 400 is a low-temperature heat pipe. Furthermore, it is also provided that the low temperature TN of the flow heat medium S, starting from the air-water heating volume 62, is greater than the outside temperature TA in the supply air pipe arrangement 1000.

[0132] The drying system 1 preferably has a heat feed arrangement 500 configured to feed a first or more flow heat media S, X having a preheat inflow temperature TV into the preheat flow volume 12, wherein the preheat inflow temperature TV is lower than the initial temperature TI. In particular, at least the first flow heat medium S is passed from the flow heat arrangement 400 directly, or via intermediate arrangements, into the heat feed arrangement 500. This can also be done independently of the associated features.

[0133] Furthermore, it is provided that the drying system 1 has one or more heat exchanger devices 50 between the air-to-air heat exchanger 20 and the air-to-water heat exchanger 60. The heat exchanger device 50 or the heat exchanger devices 50 utilize heat from the exhaust air K in the outgoing LLW exhaust air flow arrangement 200 to heat a medium W, in particular essentially water. In particular, a gas medium, in particular essentially combustion gas, is used as a carrier medium for drying the drying medium in the drying system 30.

[0134] In particular, an existing drying system 1 with at least one air-to-air heat exchanger 20 and a drying system 30 can be retrofitted to a drying system 1 shown in Figure 1.

[0135] The drying system 1 is preferably designed such that the fresh air in the incoming LLW fresh air flow arrangement 2000 with the regulated fresh air inflow temperature T_G thermally influences the LLW outlet temperature T AT in the outgoing LLW fresh air flow arrangement 3000 at least indirectly, in particular directly. An indirect influence generally occurs when additional components are arranged between the LLW fresh air flow arrangement 2000 and the outgoing LLW fresh air flow arrangement 3000. In particular, an increasing fresh air inflow temperature T_G leads to an increasing outlet temperature T AT and a decreasing fresh air inflow temperature T_G leads to a decreasing LLW outlet temperature T AT.

[0136] This allows the fresh air to be heated to a higher temperature than in existing systems compared to conventional air-to-air heat exchangers 20. Consequently, the drying air in the drying system 30 is not cooled as much as in the prior art or as in a conventional counterflow heat exchanger. As a result, the temperature level in the exhaust air duct arrangement 5000 is maintained at the outlet of the drying system 30, which is designed as an example air-to-air heat exchanger, and subsequent processes can be supplied with high calorific values ​​and a temperature gradient.

[0137] Where temperatures are mentioned above, these are preferred but not strictly limiting. For example, deviations of up to and including 20 percent, but at least up to and including 10 percent, may be included. It is particularly preferable for the temperature conditions to be scalable, provided the drying system technically allows this.

[0138] If the figure description contains definitions, these can also apply in isolation and do not necessarily have to be in the context of the entire figure 1.

[0139] The following example of the drying system 1 corresponds to Figure 1 and is not limiting in nature. In particular, the features can be excluded or combined with one another according to the teachings of the individual claims from the following explanation. The drying system 1 includes, in particular, the preheating heat exchanger 10, the air-to-air heat exchanger 20, and the drying system 30. Optionally, the heat exchanger device 50 with the described features can be integrated into the drying system 1. Furthermore, optionally, the air-to-water heat exchanger 60 with the described features can be integrated into the drying system 1. Furthermore, optionally, the media heat exchanger 40 with the described features can be integrated into the drying system 1. It is possible for only the heat exchanger device 50, only the air-to-water heat exchanger 60, or only the media heat exchanger 40 to be included.However, permutations of heat exchanger device 50, air-water heat exchanger 60 and media heat exchanger 40 are also possible.

[0140] The fresh air flows via the supply air line arrangement 1000 into the preheating heat exchanger 10, in particular into its preheating volume 11, and leaves the preheating heat exchanger 10 via the feeding LLW fresh air flow arrangement 2000. Likewise, a first flow heat medium S, in particular essentially water, and optionally further flow heat media X flow into the preheating heat exchanger 10, in particular into the preheating flow volume 12, and then leaves the preheating heat exchanger 10. The fresh air flowing into the preheating volume 11, with its outside temperature TA, has a lower temperature than the first or further flow heat media S, X with the preheating inflow temperature TV, so that the fresh air subsequently has a regulated fresh air inflow temperature T_G, i.e., one set as desired by heat transfer. The preheating heat exchanger 10 is operatively connected to the air-to-air heat exchanger 20.The air-to-air heat exchanger 20 has an air-to-air exhaust air volume 21. The air-to-air exhaust air volume 21 receives air, preferably moisture-laden exhaust air K, particularly preferably moisture-laden exhaust air K from the drying process in the drying system 30, at an initial temperature TI via an incoming air-to-air exhaust air flow arrangement 100 and discharges this air via the outgoing air-to-air exhaust air flow arrangement 200 at the subsequent exhaust air temperature TAF. The air-to-air heat exchanger 20 also has an air-to-air fresh air volume 22. The LLW fresh air volume 22 takes in the fresh air from the incoming LLW fresh air flow arrangement 2000 with the controlled fresh air inflow temperature T_G and delivers this fresh air to the outgoing LLW fresh air flow arrangement 3000 with the LLW outlet temperature T AT.

[0141] The fresh air flowing from the preheating heat exchanger 10 via the incoming LLW fresh air flow arrangement 2000 into the air-to-air heat exchanger 20, in particular into the LLW fresh air volume 22, has a lower temperature than the air with the initial temperature TI from the incoming LLW exhaust air flow arrangement 100. However, the fresh air flowing via the incoming LLW fresh air flow arrangement 2000 into the air-to-air heat exchanger 20, in particular into the LLW fresh air volume 22, with its regulated fresh air inflow temperature T_G, has a higher temperature than the ambient air. This results in the LLW outlet temperature T_AT having a higher temperature than if the fresh air had flowed into the LLW fresh air volume 22 at the ambient temperature.This also means that the temperature in the LLW exhaust air volume 21 does not drop as in conventional drying systems, so that the air in the outgoing LLW exhaust air flow arrangement 200 with the exhaust air follow-up temperature T AF is of high interest and usable for subsequent processes, unlike in conventional drying systems.

[0142] As further illustrated in Figure 1, and independent of the other features of this figure, the fresh air is provided with the LLW outlet temperature T AT via the outgoing LLW fresh air flow arrangement 3000 into the media heat exchanger 40. Various heat transfer processes can take place in this media heat exchanger 40, so that the fresh air subsequently flows at a predefined process temperature TP from the media heat exchanger 40 and along the flow arrangement 4000 into the drying system 30. If no media heat exchanger 40 is provided, the LLW outlet temperature T AT can also directly correspond to the predefined process temperature TP.

[0143] Coming from the flow arrangement 4000, or if no media heat exchanger 40 is present, from the outgoing LLW fresh air flow arrangement 3000, the fresh air for the drying process of the drying medium flows into the drying system 30 and, after the drying process of the drying medium, flows from there into the exhaust air duct arrangement 5000, whereby the fresh air is then moisture-laden exhaust air K. The moisture from the exhaust air K originates from the dried drying medium.

[0144] This moisture-laden exhaust air K can be fed directly or indirectly, for example after further heat transfer processes, into the air-to-air heat exchanger 20 via the feeding LLW exhaust air flow arrangement 100 at the temperature which is referred to as the initial temperature TI from the process step onwards.

[0145] The air flowing from the air-to-air heat exchanger 20 along the outgoing LLW exhaust air flow arrangement 200 can flow via the heat exchanger device 50, interacting with a liquid medium for heat transfer, along one or more fluid lines to the air-to-water heat exchanger 60. Optionally, the exhaust air flowing from the air-to-air heat exchanger 20 along the outgoing LLW exhaust air flow arrangement 200 can also flow directly to the air-to-water heat exchanger 60.

[0146] The air-water heat exchanger 60 has, in particular, an air-water transfer volume 61 and an air-water heating volume 62. In the air-water heat exchanger 60, the exhaust air flows, in particular, through an air-water transfer volume 61 and exchanges heat with a first flow heat medium S flowing through the air-water heating volume 62. The first flow heat medium S and / or further flow heat media X can then flow out of the air-water heating volume 62 through a flow heat arrangement 400 into a heat feed arrangement 500, which in turn flows into the preheat flow volume 12 of the preheat heat exchanger 10 for heat exchange. Following this cycle, residual heat from the preheat heat exchanger 10 is returned to the preheat heat exchanger 10.

[0147] List of reference symbols

[0148] I Drying system

[0149] 10 preheating heat exchangers

[0150] II Preheating volume

[0151] 12 Preheating flow volumes

[0152] 20 air-to-air heat exchangers

[0153] 21 LLW- exhaust air volumes

[0154] 22 LLW fresh air volume

[0155] 30 drying plant

[0156] 40 media heat exchangers

[0157] 50 heat exchanger device

[0158] 60 air-water heat exchangers

[0159] 61 LWW transmission volume

[0160] 62 LWW heating volume

[0161] 100 incoming LLW exhaust air flow arrangement

[0162] 200 outgoing LLW exhaust air flow arrangement

[0163] 300 fluid line(s)

[0164] 400 flow heat arrangement

[0165] 500 heat feed arrangement

[0166] 1000 supply air duct arrangement

[0167] 2000 feeding LLW fresh air flow arrangement

[0168] 3000 outgoing LLW fresh air flow arrangement

[0169] 4000 flow arrangement

[0170] 5000 exhaust air duct arrangement

[0171] LLW air-to-air heat exchanger

[0172] TI initial temperature

[0173] TA outside temperature

[0174] T_G Controlled fresh air inlet temperature

[0175] T_N Low temperature TV Preheat inflow temperature

[0176] T AT LLW- Outlet temperature

[0177] T_AF exhaust air follow-up temperature

[0178] T_N Low temperature TP Predefined process temperature

[0179] S First flow heat medium, in particular essentially water

[0180] X Multiple flow heat medium

[0181] W Liquid medium, especially water K Moisture-laden exhaust air

Claims

Claims 1. Drying system for drying a drying medium, in particular for drying fibrous materials, the drying system (1) comprising at least the following components: an air-to-air heat exchanger (LLW) (20) with an LLW exhaust air volume (21) and an LLW fresh air volume (22), the air-to-air heat exchanger (20) comprising: - a feeding LLW exhaust air flow arrangement (100) for the inflow of exhaust air (K) with an initial temperature (TI) into the LLW exhaust air volume (21) and - a discharging LLW exhaust air flow arrangement (200) with an exhaust air sequence temperature (T AF) for discharging exhaust air (K) from the LLW exhaust air volume (21), - a feeding LLW fresh air flow arrangement (2000) for the inflow of fresh air with a controlled fresh air inflow temperature (T_G) into the LLW fresh air volume (22) and - an outgoing LLW fresh air flow arrangement (3000) for outflowing fresh air with an LLW outlet temperature (T AT) from the LLW fresh air volume (22), wherein the LLW exhaust air volume (21) and the LLW fresh air volume (22) are designed such that heat can be transferred from the LLW exhaust air volume (21) to the LLW fresh air volume (22) in order to heat the fresh air; a drying system (30) designed to dry the drying medium, wherein the drying system (30) is designed such that the fresh air heated at least by the air-to-air heat exchanger (20) and flowed out at least indirectly from the LLW fresh air flow arrangement (3000) interacts with the drying medium as drying air and absorbs evaporated moisture from the drying medium and discharges it as moisture-laden exhaust air (K) to an exhaust air duct arrangement (5000);wherein the drying system (1) is designed to guide the exhaust air (K) from the drying plant (30) via the exhaust air duct arrangement (5000) and via the LLW exhaust air flow arrangement (100) at least indirectly to the air-air heat exchanger (20), so that an at least indirect transfer of the heat from the exhaust air; (K) in the exhaust air duct arrangement (5000) to the fresh air in the air-to-air heat exchanger (20); wherein the air-to-air heat exchanger (20) energetically reduces the exhaust air (K) from the feeding LLW exhaust air flow arrangement (100); wherein the drying system (1) has a preheating heat exchanger (10) with a preheating volume (11) and a preheating flow volume (12), wherein the preheating heat exchanger (10) is designed to heat fresh air, in particular ambient air, from an outside temperature (TA) to the regulated fresh air inflow temperature (T_G);wherein the drying system (1) has a supply air line arrangement (1000) for feeding the fresh air at the outside temperature (TA) into the preheating heat exchanger (10), wherein the feeding LLW fresh air flow arrangement (2000) connects the preheating heat exchanger (10) at least indirectly to the air-to-air heat exchanger (20) in order to provide the fresh air with the regulated fresh air inflow temperature (T_G) for the air-to-air heat exchanger (20), in particular for the LLW fresh air volume (22) of the air-to-air heat exchanger (20); 2. Drying system according to claim 1, wherein the drying system (1) has at least one media heat exchanger (40) which is designed to be supplied with a medium in order to adjust the fresh air from the outgoing LLW fresh air flow arrangement (3000) to a predefined process temperature (TP), which is supplied to the drying system (30) via a flow-through arrangement (4000) comprised by the drying system (1).

3. Drying system according to claim 2, wherein the media heat exchanger (40) is designed to be supplied with fresh steam, oil, hot water, brine, hydrogen, district heating, electricity, gas combustion and / or a mixture thereof in order to adjust the fresh air to the predefined process temperature (TP).

4. Drying system according to one of claims 2 or 3, wherein the media heat exchanger (40) has one or more waste heat exchangers between the air-to-air heat exchanger (20) and the drying system (30), wherein the waste heat exchanger(s) of the media heat exchanger (40) at least indirectly uses or use heat from a self-sufficient steam condensate system which is designed to dry the drying medium in the drying system (30) in order to heat the fresh air of the LLW fresh air flow arrangement (3000) to the predefined process temperature (TP) and to pass it on to the drying system (30) by means of the flow arrangement (4000).

5. Drying system according to at least one of claims 1 to 4, wherein the drying system (1) comprises an air-water heat exchanger (LWW) (60) with an LWW transfer volume (61) and an LWW heating volume (62), wherein the air-water heat exchanger (60) is designed to heat a first liquid and / or gaseous flow heat medium (S), in particular substantially water, in the LWW heating volume (62) from heat from the LWW transfer volume (61) to the LWW heating volume (62), wherein the drying system (1) further comprises a flow heat arrangement (400) which is designed to forward the first flow heat medium (S) from the LWW heating volume (62), and wherein in particular the drying system (1) further comprises a heat feed arrangement (500) which is designed to feed the first and / or several flow heat media (S, X) into the preheating flow volume (12).

6. Drying system according to claim 5, wherein the first flow heat medium (S) flows at least indirectly from the flow heat arrangement (400) for at least indirectly regulating the fresh air inflow temperature (T_G) into the heat feed arrangement (500), and / or wherein the flow heat arrangement (400) connects the air-water heat exchanger (60) at least indirectly to the preheating heat exchanger (10) in order to heated flow heat medium (S) for at least indirect control of the fresh air inflow temperature (T_G) from the LWW heating volume (62) of the air-water heat exchanger (60) into the preheating heat exchanger (10).

7. Drying system according to one of claims 5 or 6, wherein the air-water heat exchanger (60) is a low-temperature air-water heat exchanger, wherein the flow heat medium (S) is a low-temperature heat medium with a low temperature (T_N), and wherein the flow heat arrangement (400) is a low-temperature heat pipe, wherein the low temperature (T_N) of the flow heat medium (S) starting from the air-water heating volume (62) is greater than the outside temperature (TA) in the supply air pipe arrangement (1000).

8. Drying system according to at least one of claims 1 to 7, wherein the drying system (1) has a heat feed arrangement (500), in particular the heat feed arrangement (500) according to one of claims 5 to 7, which is designed to feed a first or more flow heat media (S, X) with a preheat inflow temperature (TV) into the preheat flow volume (12), wherein the preheat inflow temperature (TV) is lower than the initial temperature (TI).

9. Drying system according to at least one of claims 1 to 8, wherein the drying system (1) has one or more heat exchanger devices (50) between the air-to-air heat exchanger (20) and the air-to-water heat exchanger (60), wherein the heat exchanger device(s) (50) uses or use heat from the exhaust air (K) in the outgoing LLW exhaust air flow arrangement (200) to heat a medium (W), in particular substantially water.

10. Drying system according to at least one of the preceding claims, wherein a gas medium, in particular substantially combustion gas, is used as a carrier medium for drying the drying medium in the drying system (30).

11. Drying system according to at least one of the preceding claims, wherein an existing drying system (1) with at least one air-air heat exchanger (20) according to at least one of claims 1 to 10 and a drying system (30) according to at least one of claims 1 to 10 is retrofitted to a drying system (1) according to at least one of claims 1 to 10.

12. Drying system according to at least one of the preceding claims, wherein the drying system (1) is designed such that the fresh air in the feeding LLW fresh air flow arrangement (2000) with the regulated fresh air inflow temperature (T_G) thermally influences the LLW outlet temperature (T AT) in the feeding LLW fresh air flow arrangement (3000) at least indirectly, in particular directly, wherein in particular a rising fresh air inflow temperature (T_G) brings about a rising outlet temperature (T AT) and a rising exhaust air follow-up temperature (T AF) and a falling fresh air inflow temperature (T_G) brings about a falling LLW outlet temperature (T AT) and a falling exhaust air follow-up temperature (T AF).

13. A drying method for drying a drying medium using a drying system (1) according to at least one of claims 1 to 12, the drying method comprising at least the following step: Heating the fresh air in the preheating heat exchanger (10), in particular in the preheating volume (11), from the outside temperature (TA) to the controlled fresh air inflow temperature (T_G).

14. Drying method according to claim 13, wherein the heating of the fresh air in the preheating heat exchanger (10), in particular in the preheating volume (11), takes place under the influence of the first and / or more flow heat media (S, X) fed from the heat feed arrangement (500) according to at least one of claims 5 to 12 into the preheating flow volume (12).

15. Drying medium, in particular fiber material, dried by a drying process according to at least one of claims 13 or 14.

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