Adsorption type dryer

Abstract

The invention relates to a method for drying a compressed gas, in particular compressed air, by means of an adsorption dryer having at least one pressure vessel with an adsorption material for adsorbing moisture from the compressed gas, in a drying operation for drying the compressed gas, compressed gas flows from the drying inlet through the drying section to the drying outlet through the pressure vessel along the adsorbent material and flows out as dried compressed gas, in a regeneration operation for regenerating the adsorbent material, regenerated gas flows from the drying outlet through the drying section to the drying inlet through the pressure vessel along the adsorbent material, in the drying mode, moisture is extracted from the adsorbent material, and in the regeneration mode, partial heating is carried out in a heating region in the pressure vessel, the heating region being arranged only in a partial region of the pressure vessel adjacent to the drying inlet.

Description

Technical Field

[0001] This invention relates to a method for drying compressed gas and an adsorption dryer. Background Technology

[0002] Adsorption dryers are known, and are particularly used for drying compressed air, or for drying other gases. Any embodiment of compressed air drying can also be applied to drying other gases.

[0003] For compressed air drying, adsorption methods are commonly used, where a stream of compressed air comes into contact with a solid adsorbent material. The adsorbent material absorbs a portion of the water vapor contained in the compressed air stream, thereby drying the compressed air. This increases the amount of water bound (adsorbed) in the adsorbent material. When the adsorbent material has absorbed so much water that it can no longer adequately dry further compressed air, the water must first be at least partially removed from the adsorbent material before it can be used again to dry compressed air. Removing water from the desiccant is called regeneration of the adsorbent material. To achieve continuous drying technically, multiple containers are typically provided so that when the adsorbent material in one container is being regenerated, another container that has already been regenerated is always available for drying.

[0004] One known regeneration method involves reducing the pressure of a portion of already dried compressed air to a low level and guiding it through a container from which the adsorbent material to be regenerated is to be regenerated. The flow direction here is typically opposite to the flow direction during compressed air drying. Dryers operating using this method are called cold-regeneration adsorption dryers.

[0005] The partial pressure of water vapor in an air stream can be as high as the vapor pressure of water. This limits the partial density of water vapor in the air. Compressed air to be dried is typically saturated with water vapor to 100%, reaching the vapor pressure of water and thus the maximum possible partial density. Given that the temperatures during drying and regeneration are approximately the same, the volume of the regenerated air must therefore be at least the same as the volume of the previously dried compressed air. Therefore, the proportion of compressed air that must be depressurized must, at approximately the same temperature, be at least as large as the pressure ratio during regeneration and drying. This is because, at approximately constant temperature, the density of an ideal gas is proportional to its pressure.

[0006] The disadvantage of this method is that a significant portion of the compressed air used for regeneration and decompression is no longer available for further use, necessitating additional compression of the compressed cavity relative to the actual required amount of compressed air. Therefore, this method is very energy-intensive.

[0007] Another known method for regeneration involves performing regeneration at elevated temperatures. The higher the temperature, the higher the vapor pressure of the water. Here, heated ambient air is used for regeneration. The temperature during regeneration is chosen so high that the vapor pressure of the water is much higher than the partial pressure of water vapor contained in the ambient air. Thus, regeneration is still possible even though the ambient air naturally contains water vapor. Dryers operating using this method are called thermally regenerated adsorption dryers.

[0008] In this method, so much heat must be introduced via heated ambient air that the dried material is heated to a high temperature, such as 150°C, and water is desorbed from the dried material. Desorption means that water changes from a bound (adsorbed) state to a gaseous state. The heating energy required in this method is lower than the energy used in the aforementioned methods to produce compressed air for regeneration.

[0009] Disadvantageously, the dried material is at a high temperature at the end of regeneration. Consequently, after container switching, compressed air flows directly through the hot dried material. As a result, the compressed air is heated to an undesirably high temperature, and the drying effect deteriorates because the hotter the dried material, the less moisture it can remove from the compressed air.

[0010] To mitigate these drawbacks, the dried material is cooled before being reused for compressed air drying. Ambient air and / or depressurized compressed air can be used to cool the material. Cooling with ambient air is limited because the dried material absorbs water vapor from the ambient air during the cooling process, thus requiring less compressed air to dry. Furthermore, cooling with depressurized compressed air can only be implemented to a very limited extent if an energy advantage over regeneration methods using depressurized compressed air is to be achieved.

[0011] Therefore, the disadvantages of high temperature and high residual humidity after switching directly to compressed air drying in the container can only be slightly mitigated, but not eliminated.

[0012] US 5,087,178 A describes a drying method in which regeneration is carried out using depressurized compressed air, as in a cold regenerative adsorption dryer. Before depressurization, the compressed air is heated by oil from a screw compressor equipped with an oil injection device. The introduced heat improves desorption. However, the heat input is limited by the heat capacity of the regeneration air. Therefore, a considerable portion of the compressed air is still required for regeneration. Disadvantageously, the desiccant is heated after regeneration, and as described, this residual heat causes a significant increase in temperature and residual humidity after switching back to drying.

[0013] A similar drying method is also described in US 4,898,599 A. However, to improve regeneration, the respective containers are directly heated during regeneration by hot oil from a screw compressor equipped with an oil injection device. As an alternative solution to regeneration using reduced-pressure compressed air, the extraction of water vapor is proposed. However, given the low vapor pressure of water, the containers must be evacuated to a very low pressure.

[0014] An advantage over US 5,087,178 A is that heat input can be independent of regenerated air. However, the disadvantage of significant waste heat is also present in US 4,898,599 A.

[0015] In EP 1 010 452 B1, at least a portion of the dried material is also heated independently of compressed air via resistance or microwave heating. Here, heating of the dried material is achieved through two or more independently activatable heating devices, such that heating of the dried material in the upper part of the container can be completed while heating in the lower part of the container is still active. This method allows for a reduction in the amount of compressed air required for cooling. However, a significant amount of cooling air is still needed to cool the entire contents of the container. An adsorption buffer is described in US 3,204,388 A. A vacuum regeneration method is described in KR 101214541 B1. Summary of the Invention

[0016] Therefore, the objective of this invention is to solve at least one of the problems mentioned above. In particular, a method should be developed that has the lowest possible energy requirement and where the temperature and humidity of the compressed air are not too high after switching the regenerated container to compressed air drying. At least an alternative solution to the solutions known to date should be proposed.

[0017] According to the present invention, a method according to claim 1 is provided. Therefore, the method relates to drying compressed gases, particularly compressed air, using an adsorption dryer. This adsorption dryer has at least one pressure vessel with an adsorbent material for adsorbing moisture from the compressed gas. This adsorbent material may be granules disposed within the pressure vessel and circulated by compressed air during operation.

[0018] The method operates such that, during a drying operation for drying compressed gas, the compressed gas flows from the drying inlet through the drying section to the drying outlet, across the pressure vessel, along the adsorbent material, and exits as dried compressed gas. Therefore, the compressed gas flows through the pressure vessel along the adsorbent material, which can exist as particles, and releases moisture to the adsorbent material. Consequently, the dried compressed gas has less moisture than it did immediately upon entering the drying inlet and before flowing along the adsorbent material through the drying opening.

[0019] Due to structural limitations and / or for functional purposes, pressure vessels may not be completely filled with adsorbent material. In such cases, the pressure vessel has transition regions extending to the adsorbent material in the areas of the dry inlet and / or dry outlet, where no adsorbent material is present. Each transition region may occupy approximately 2%-10% of the length from the dry inlet to the dry outlet. The dry section refers to the section within the adsorbent material, i.e., the section from the dry inlet to the dry outlet minus at least one transition region.

[0020] In the regeneration operation used to regenerate the adsorbent material, the regeneration gas flows from the drying outlet through the drying section to the drying inlet, passing through the pressure vessel and flowing along the adsorbent material, where moisture is extracted from the adsorbent material. Therefore, in the regeneration operation, the flow direction is opposite to that in the drying operation, causing the regeneration gas to flow in the opposite direction to the compressed gas to be dried, and where the moisture already absorbed by the adsorbent material from the compressed gas to be dried is extracted.

[0021] Furthermore, it is proposed that during regeneration operation, partial heating occurs in the heating zone within the pressure vessel. Therefore, the pressure vessel is heated during regeneration operation, but not throughout the entire region. Here, the heating zone is located adjacent to the drying inlet and only within a portion of the pressure vessel. Thus, the regeneration gas first flows through the unheated zone within the pressure vessel and then flows through the heated zone.

[0022] The regenerated gas is heated, thereby increasing its water vapor absorption capacity. This allows it to absorb more water. The heated adsorbent material also releases moisture more effectively.

[0023] However, it has been recognized that the compressed air to be dried releases most of its moisture in the region where it flows in, i.e., near the drying inlet. Therefore, the adsorbent material has essentially the highest moisture content near the drying inlet, which decreases towards the drying outlet. This understanding is precisely what the proposed method takes full advantage of. During regeneration operation, the regeneration gas therefore first flows into the region of the pressure vessel where the adsorbent material has absorbed relatively little moisture. Furthermore, the regeneration gas itself is then quite dry, i.e., it has not yet absorbed any moisture or has not absorbed much moisture. Therefore, the relatively dry regeneration gas can absorb the small amount of moisture in the adsorbent material in the region near the drying outlet quite well.

[0024] In this sense, the amount of moisture absorbed by the regenerated gas increases from the dry outlet to the dry inlet. Therefore, even though the regenerated gas has absorbed a significant amount of moisture towards the dry inlet, it still needs to absorb a considerable amount of moisture from the adsorbent material because the adsorbent material has a high moisture content near the dry inlet.

[0025] Therefore, the pressure vessel is heated in this region near the drying inlet. The regeneration gas, especially air, is also heated and can absorb more moisture because its water vapor absorption capacity is increased by heating.

[0026] However, it is proposed that this heating be performed only in certain areas of the pressure vessel. Heating should only be performed where increased steam absorption capacity is required. It has been recognized, as mentioned above, that this is in the area of ​​the dry inlet.

[0027] It is also recognized that it is particularly advantageous for the drying air to flow in one direction, while the regenerated gas flows in the opposite direction. The flow direction of the compressed gas to be dried creates a corresponding gradient for the absorption of moisture in the pressure vessel, which is well matched by the regenerated gas flowing in the opposite direction, especially by targeted heating of the regenerated gas before its outflow.

[0028] Therefore, the improvement of the method compared to the prior art is achieved by targeting heat input only where increased efficiency is required. With the drying inlet located at the bottom of the container, most of the water vapor during drying is already adsorbed in the lower part of the pressure vessel. By targeting heat input to the lower part of the container, the regenerated air flows through this area just before exiting the container, increasing the water vapor absorption capacity of the regenerated air only from where higher capacity is needed, since only there can a large amount of water be released to the air. Unnecessary overheating of the drying material is avoided.

[0029] According to one aspect, the heating zone is located in 0% to 80%, preferably 0% to 60%, and especially 0% to 50% of the dry section. Therefore, the heating zone is located in the area facing the drying inlet.

[0030] Alternatively, it is proposed that the heating zone extends over at least 20% of the dry road section, preferably at least 30% of the dry road section, and especially at least 40% of the dry road section. In particular, it is proposed that no heating, or at most reduced heating, is carried out outside the heating zone, wherein the energy input per unit volume is less than 30% compared to the heating zone.

[0031] It has been recognized that it is particularly advantageous to heat approximately half of the drying section, i.e., the half facing the drying inlet. Therefore, the heating zone is located near the drying inlet. It lies within the 0% to 80% section, and thus certainly not within the 80% to 100% section. For the reasons stated above, this section can be left empty and does not require heating. However, it is also recognized that setting the heating within the range of 0% to 60% may be sufficient. 0% to 50% is particularly advantageous because this allows approximately half of the drying section to be heated. The pressure vessel can be installed, for example, vertically, with the drying inlet at the bottom and the drying outlet at the top. In this essentially cylindrical vessel, the adsorbent material or the frame containing the adsorbent material can be placed inside the pressure vessel, for example, on supports, such that the adsorbent material, thus the beginning of the drying section, can have a distance of approximately 5% from the drying inlet.

[0032] Alternatively, it is proposed that the heating zone extends over at least 30% of the dry road section, particularly at least 40% of the dry road section, wherein it is preferably located in the aforementioned 0% to 80%, 0% to 60%, or 5% to 50% sections. This allows heating of a significant area of ​​the dry road section, i.e., at least 30%. A larger area of ​​at least 40% can achieve a higher regeneration efficiency, but this may result in higher energy input. The heating zone should not extend over the entire dry road section, and therefore preferably extends over at most 70%, particularly at most 60%, of the dry road section.

[0033] Heating should not be performed outside the heating zone. Therefore, no heating is performed outside the heating zone throughout the entire regeneration operation. In principle, reduced heating can be considered, with energy input per unit volume reduced by 30% compared to the heating zone. However, energy input per unit volume can also be less than 10% compared to the heating zone. Heating outside the heating zone is generally discouraged, but if heating exists there for other reasons, such as for drying operations, this is not excluded; however, this would only cause undesirable energy input and should be avoided as much as possible.

[0034] According to one aspect, as part of the dried compressed gas, a portion of the compressed gas is used as regeneration gas, and the portion of the compressed gas at the dried outlet is introduced into a pressure vessel, and the compressed gas portion undergoes depressurization when or before being introduced into the pressure vessel.

[0035] Therefore, a portion of the dried compressed gas can be used for regeneration, i.e., for drying the adsorbent material. A practical feasibility of this implementation lies particularly in using two pressure vessels that operate alternately in drying or regeneration operation. If one pressure vessel is operating in drying operation, it continuously outputs dried compressed air, which can be used for regeneration in the other vessel operating in regeneration operation, i.e., for drying the adsorbent material. To enable the dried compressed gas, i.e., the particularly dried compressed air, to absorb more moisture from the adsorbent material, even in unheated areas, the dried compressed gas undergoes depressurization. Thus, the compressed gas itself, dried at a higher pressure, can approximately reabsorb moisture from the adsorbent material by reducing the pressure.

[0036] After the compressed gas fraction is used for regeneration, it may be discharged as humid gas or humid compressed air, and may no longer be under pressure or overpressure, or some of its moisture may be released again in a water separator. Such a water separator may operate, for example, via condensation.

[0037] One approach proposes heating within a pressure vessel using a heat exchanger, where the heat transfer section of the heat exchanger is surrounded by an adsorbent material to transfer heat to the adsorbent. However, during regeneration operation, the heat exchanger also directly transfers heat to the regeneration gas, specifically the regeneration air.

[0038] It is recognized here that by utilizing a heat exchanger, heat generated elsewhere in the system can be used to heat the pressure vessel. Here, the heat exchanger has a heat transfer section disposed within the pressure vessel. This heat transfer section is configured such that it is surrounded by an adsorbent material within the pressure vessel. Specifically, the adsorbent material is configured as granular, thus being a bulk material. The heat transfer section is configured and thus disposed within the pressure vessel such that this granular bulk material can surround the heat transfer section. In particular, the bulk material can be injected between portions of the heat transfer section, or the bulk material can be injected between portions of the heat transfer section.

[0039] For this purpose, the heat transfer section can be configured, for example, in a cylindrical or disc-shaped form, or in the form of circular sections or multiple plate-shaped sections arranged parallel to each other, such that particles can be poured around them, and in the case of sections arranged parallel to each other, there is sufficient spacing between them so that particulate material can be poured in.

[0040] It is particularly recognized here that the heating of the regenerated gas can be carried out directly and indirectly, i.e., directly by the regenerated gas also flowing through the heat transfer section. Indirectly, the regenerated gas can be heated by heating the adsorbent material surrounding the heat transfer section, and then heating the regenerated gas as it flows through or through the adsorbent material.

[0041] According to one aspect, compressed gas is generated by a pressure generating device, particularly a compressor, and the waste heat from the pressure generating device is used to heat the heating zone during regeneration. In particular, it is proposed that heating oil from a screw compressor equipped with an oil injection device be used to heat the heating zone during regeneration.

[0042] It is particularly recognized that there is a significant amount of heat available for heating during regeneration to generate the pressure of the compressed gas. By using a small heating zone that heats only a portion of the drying section, the capacity of this heating zone is also enhanced, allowing for heating by means of waste heat from the pressure generating device or compressor, thereby introducing sufficient heating energy. Compressed air systems with adsorption dryers and pressure generating devices can thus be designed efficiently.

[0043] A screw compressor with an oil injection device causes the oil to heat due to its function, and the oil can be used for heating by means of a heat exchanger, especially as a liquid heat transfer medium in such heat exchangers. The term heat transfer medium can also be used synonymously as a heat medium.

[0044] According to one approach, heating of the heating zone is performed using waste heat from a pressure generating device and active heating from an energy source, particularly enabling the temperature of the heating medium heated from waste heat to be further increased to a predetermined temperature through active heating.

[0045] Therefore, even if the waste heat alone is insufficient for heating, the heating zone can utilize the waste heat from the pressure generating device, particularly the screw compressor. Active heating can be supplemented by further heating the heat medium already heated by the waste heat from the pressure generating device. For example, the oil in a screw compressor that is injected with oil can have a temperature of 60°C to 100°C. If the temperature is, for example, 60°C, but 100°C is meaningful in a heat exchanger, particularly in the heat transfer section, then the exemplary 60°C oil can be raised by 40°C to 100°C and then used accordingly in the heat exchanger.

[0046] A particular advantage is that, in any case where heated oil is used in a screw compressor that employs injected oil, cooling of the screw compressor is simultaneously achieved. Of course, this only applies if actively and additionally heating the heated oil no longer introduces energy compared to releasing it again in the heated zone.

[0047] According to one aspect, at least two pressure vessels are used. In combined operation, at least one pressure vessel operates in drying operation, while the other pressure vessel operates in regeneration operation. The pressure vessel operating in drying operation outputs dried compressed gas, a portion of which is diverted as a compressed gas fraction and supplied to the pressure vessel operating in regeneration operation, and thereby used as regeneration gas.

[0048] In particular, using exactly two pressure vessels, which can essentially operate alternately, allows one pressure vessel to operate in drying mode while the other operates in regeneration mode. Therefore, the pressure vessel operating in drying mode not only provides the required compressed gas, especially the required compressed air, but also additionally provides regeneration gas, specifically regeneration air in the case of compressed air. The advantages described above regarding the use of compressed gas proportions for regeneration are thus well achieved.

[0049] Therefore, combined operation describes the scenario where drying and regeneration operations are carried out in parallel. However, it is also possible for only drying operations to occur.

[0050] However, it should be noted that drying and regeneration operations do not necessarily have to continue simultaneously. For example, regeneration may occur, and the regeneration operation may have already completed, while the drying operation continues for some time. Then, the drying operation only produces the dried compressed gas that has been called up, without diverting any portion of it for regeneration.

[0051] The drying operation continues until the adsorbent material in the pressure vessel operating in the drying operation can no longer adequately absorb moisture. Once the adsorbent material can no longer adequately absorb moisture, perhaps slightly earlier, a switch can be made so that the pressure vessel previously operating in the drying operation is now operating in the regeneration operation. The pressure vessel previously operating in the regeneration operation is now operating in the drying operation.

[0052] The principle has been described based on two pressure vessels that can operate alternately. However, more pressure vessels may also be used. In particular, it is considered that multiple pressure vessels are always operating in drying operation and multiple are operating in regeneration operation. Whether to use two or more pressure vessels may also depend on the standard existing structural dimensions of the pressure vessels and the volume of compressed gas that needs to be dried per unit time. If more than two pressure vessels are used, it is also considered that at least one pressure vessel is operating in drying operation, at least one pressure vessel is operating in regeneration operation, and at least one pressure vessel is in standby operation.

[0053] One approach proposes that, when switching from drying to regeneration operation, the flow of compressed gas from the drying inlet to the drying outlet is first interrupted, followed by heating of the heating zone. After heating begins, a predetermined heating time is waited until the regeneration gas enters the pressure vessel. This allows the adsorbent material to be heated in the heating zone first, before the regeneration gas is introduced, ensuring that the regeneration gas flows through the heated zone from the outset, thus achieving enhanced water vapor absorption capacity in the heating zone from the beginning.

[0054] This prevents the regenerated gas from being wasted or underutilized initially. It is also recognized that, particularly in conjunction with waste heat heating, preheating the heating zone before the regenerated gas flows through does not cause energy loss or causes negligible energy loss. Furthermore, it is recognized that the adsorbent material can have a high heat capacity, thus preheating essentially causes only that the thermal energy is stored and, in its essence, released unused.

[0055] It was also recognized that there is sufficient time for regeneration during the operation of the adsorption equipment. This is particularly true in favorable alternating operations, where there is sufficient time for regeneration during the switching between drying and regeneration operations between at least two containers.

[0056] The predetermined heating time can be calculated based on the heat capacity of the adsorbent material in the heating zone and the heat introduced per unit time, i.e., thermal energy. Here, the adsorption equipment is designed so that the introduced heat is coordinated with the heat capacity of the adsorbent material in the heating zone. The heating time will be in the range of 3 to 25 minutes.

[0057] According to one approach, when switching from regeneration operation to drying operation, heating is first stopped, and after heating is stopped, a predetermined cooling period is allowed until compressed gas enters the pressure vessel. Specifically, it is proposed that after heating is stopped, regeneration gas continues to flow through the pressure vessel for part or all of the cooling period.

[0058] By ending the heating process before introducing compressed gas during the drying operation, cooling can be achieved in the pressure vessel, particularly in the heated area, along with other components within the heated zone. This prevents the compressed gas to be dried from being heated in the heated zone, thereby increasing its water vapor absorption capacity and releasing less moisture. Otherwise, there would be a risk that the compressed gas to be dried would not be sufficiently dried.

[0059] In particular, cooling can be facilitated by allowing the regenerated gas to continue flowing through the pressure vessel after heating has ended, thereby also flowing through the heated area. Thus, the regenerated gas can cool the heated area. Ideally, this occurs over the entire cooling time, but may be slightly shorter for technical reasons.

[0060] Specifically, in the alternating operation of at least two pressure vessels between drying and regeneration operations, the drying operation can continue in at least one pressure vessel while preparation for drying operation is carried out in the other. Preparation is achieved through the aforementioned final heating during continued flow of regeneration gas. Therefore, the regeneration gas continuing to flow through the pressure vessels during the cooling period can continue to be supplied by the pressure vessel still operating in drying operation.

[0061] Alternatively, the pressure vessel operating during drying can be switched to standby mode. In standby mode, the flow of compressed gas to be dried through the pressure vessel is interrupted, especially when no compressed gas is requested at that moment. Consequently, no other gas flows through the pressure vessel. This standby mode differs from the cooling phase after heating has ended and before the actual drying operation begins with the introduction of compressed gas to be dried. In the cooling phase, it is specifically proposed that regeneration gas flow through the pressure vessel.

[0062] The cooling time can be calculated based on the mass of the regenerated gas flowing through the container relative to the mass of the heated adsorbent now awaiting cooling. The adsorbent can also be referred to as a desiccant. It has been recognized that the ratio of the mass of the regenerated gas to the mass of the heated adsorbent used for cooling ranges from 0.025 kg / kg to 0.22 kg / kg. Therefore, the cooling time can be the time required for a corresponding mass of regenerated gas to flow through the compressed gas container.

[0063] The cooling time therefore also depends on the flow rate, i.e., the mass of regeneration gas flowing through the pressure vessel per unit time. The flow rate and the mass of the adsorbent material being heated and then cooled again are typically coordinated. This results in a predetermined cooling time ranging from approximately 1 to 30 minutes.

[0064] According to one aspect, compressed air is dried as a compressed gas, and a portion of the dried compressed air is used as a regeneration gas, such that the regeneration air is used as the regeneration gas, wherein the regeneration air flows out into the environment of the adsorption dryer after the through-flow drying section.

[0065] Therefore, the proposed method can be particularly used for drying compressed air. It also has the advantage of using ambient air, which is converted into compressed air through compression and then dried. A portion of the dried compressed air can then be reused for regeneration and can be released back into the atmosphere without problems. This eliminates the need for further drying of the moisture-rich regeneration air.

[0066] According to one approach, during regeneration operation, the pressure inside the pressure vessel is reduced to below the pressure outside the pressure vessel, particularly below atmospheric pressure. Consequently, the pressure of the regeneration gas introduced into the pressure vessel is also reduced. This allows the regeneration gas to absorb more moisture, thereby improving the drying process of the adsorbent material, i.e., its regeneration, compared to conditions with higher pressure.

[0067] A specific compressor may exist, which can also be described as a low-pressure system. One feasible implementation is that regeneration gas is introduced as regeneration air and delivered from the pressure vessel by a compressor that reduces the pressure within the pressure vessel, particularly when the regeneration gas is air, into the environment.

[0068] According to one aspect, the dried compressed air flows through an additional pressure vessel containing adsorbent material after exiting the drying outlet, and the additional pressure vessel is not integrated into the regeneration operation.

[0069] It has been recognized that the dryness of the dried compressed air, as reflected in the pressure dew point, can fluctuate due to the alternation between drying and regeneration operations. This pressure dew point may rise, particularly after switching from regeneration to drying operation. The compressed air is then wetter than expected, making it easier to release moisture.

[0070] Therefore, an additional pressure vessel is provided for this purpose, in which moisture can be released to the adsorbent material under the elevated pressure dew point. However, the adsorbent material does not need to be dried again through a separate process. Instead, when the pressure dew point of the dried compressed air decreases again, it can reabsorb moisture from the adsorbent material in the additional pressure vessel. Thus, the additional pressure vessel is unaffected by switching between drying and regeneration operations.

[0071] One measure of the water vapor content in compressed air is the pressure dew point, which is the temperature at which the partial pressure of water vapor in compressed air is exactly equal to the vapor pressure of water at the operating pressure.

[0072] Despite the improvements, a certain increase in pressure dew point still occurs in the proposed adsorption drying method based on the proposed adsorption dryer after the container switches from regeneration to drying.

[0073] Therefore, the maximum pressure dew point can be higher than the average pressure dew point even in the proposed solutions. Furthermore, it has been recognized that the maximum pressure dew point can be an important criterion, and a solution to reduce it is sought. In particular, this should be achieved without significantly increasing energy requirements, whereas reducing the average pressure dew point requires increased energy. This should be achieved, at least without increasing heating power, regeneration air volume, or shortening drying time.

[0074] As a proposed solution, the dried compressed air flows through an additional pressure vessel containing adsorbent material after exiting the drying outlet. Therefore, it is proposed that the dried compressed air flows through an adsorption buffer, which is a container filled with drying material, i.e., an additional pressure vessel.

[0075] When the residual humidity in the compressed air briefly increases, the drying material initially absorbs most of the additional water, causing a significant decrease in the pressure dew point at the outlet of the adsorption buffer compared to the inlet. When the compressed air again reaches a lower pressure dew point during further processing, the drying material releases the additional water. This results in a slight increase in the pressure dew point during the flow-through adsorption buffer over a longer period.

[0076] Throughout the entire operating time of the adsorption buffer, the amount of water vapor in the compressed air did not decrease, but the maximum pressure dew point decreased significantly. This reduction is achieved with very high energy efficiency, as only the energy required to overcome the tiny flow resistance of the adsorption buffer is needed for operation.

[0077] According to the present invention, an adsorption dryer is also proposed. Therefore, an adsorption dryer for drying compressed gases, particularly compressed air, is proposed, and the adsorption dryer has at least one pressure vessel having an adsorbent material for adsorbing moisture from the compressed gas, and the adsorption dryer is prepared to perform a method, wherein...

[0078] - In drying operations used to dry compressed gas, the compressed gas flows from the drying inlet through the drying path to the drying outlet, passes through the pressure vessel along the adsorbent material, and exits as dried compressed gas.

[0079] - In the regeneration operation used to regenerate the adsorbent material, the regeneration gas flows from the dry outlet through the dry section to the dry inlet, across the pressure vessel, along the adsorbent material, and extracts moisture from the adsorbent material there.

[0080] - During regeneration operation, partial heating occurs in the heating zone within the pressure vessel, where...

[0081] - The heating zone and the drying inlet are located adjacent to each other only in a portion of the pressure vessel.

[0082] Specifically, the adsorption dryer is configured to perform a method according to one of the aspects or embodiments described above. Preferably, the adsorption dryer is correspondingly connected such that compressed gas and regeneration gas can flow through the pressure vessel and can also be guided via corresponding connections. For control, corresponding control devices can be provided, specifically for starting, controlling, and ending the drying and regeneration operations respectively. For heating, corresponding heating devices are provided. Furthermore, the adsorption dryer is configured for connection to a pressure generating device, particularly a compressor, and a piping system for receiving and / or transmitting compressed gas.

[0083] The functions and advantages of this adsorption dryer are derived from the description of the method for drying compressed gases.

[0084] Based on one aspect, for adsorption dryers, it is proposed that...

[0085] - The heating zone is set in a section of the drying path measured from the drying inlet to the drying outlet, specifically in the range of 0% to 80%, preferably 0% to 60%, and particularly 0% to 50%.

[0086] - And extending over at least 20%, preferably at least 30%, and especially at least 40% of the dry road section, preferably up to 70%, especially up to 60% of the dry road section and / or

[0087] - A heat exchanger is provided in the pressure vessel for heating purposes.

[0088] - It has a heat transfer section disposed in the heating area, the heat transfer section being surrounded by an adsorbent material.

[0089] Therefore, a heating zone is proposed, which is specifically positioned at the location where the regeneration of the adsorbent material is thus improved.

[0090] Based on one aspect, for adsorption dryers, it is proposed that...

[0091] - It is equipped with at least two pressure vessels, and

[0092] - The adsorption dryer is prepared for combined operation, wherein at least one pressure vessel operates in drying operation, while the other pressure vessel operates in regeneration operation.

[0093] - The pressure vessels are connected to each other so that they work together to cause the pressure vessels operating in drying operation to output dried compressed gas, a portion of which is diverted as a compressed gas fraction and supplied to the pressure vessels operating in regeneration operation, and used as regeneration gas, and / or

[0094] - An additional pressure vessel with adsorbent material is provided, wherein the additional pressure vessel is connected to the other pressure vessels such that the additional pressure vessel is not integrated into the regeneration operation.

[0095] Therefore, an adsorption dryer is specifically proposed, in which multiple pressure vessels can alternate between drying and regeneration operations. The pressure vessel operating in drying operation can release regeneration gas to another pressure vessel operating in regeneration operation. The pressure vessels are correspondingly connected to each other, allowing the flow of corresponding compressed gas from one pressure vessel to another, and enabling targeted control via corresponding valves.

[0096] The auxiliary container can be configured such that a portion of the dried compressed gas discharged from one pressure vessel is used as regeneration gas in another pressure vessel, positioned upstream of the auxiliary pressure vessel in the direction of flow of the dried compressed gas. The auxiliary pressure vessel, containing its adsorbent material, can be configured entirely passively, such that no active pressure changes, heating, or cooling occur within it.

[0097] Other aspects have been described in conjunction with the methods used for drying, and are hereby referred to.

[0098] According to the present invention, a compressed gas system for providing dried compressed gas is also provided. Therefore, a compressed gas system is provided, the compressed gas system having:

[0099] - Pressure generating devices, especially compressors for compressing gases into compressed gases.

[0100] - An adsorption dryer having multiple pressure vessels filled with adsorbent material, wherein the pressure vessels are respectively

[0101] - Features a drying section for drying compressed gas, and

[0102] - A heating zone that extends only within a portion of the dry section, wherein a heat exchanger is provided, which is connected to a compressor to heat the heating zone by means of the compressor's waste heat.

[0103] Preferably, the compressed gas system has an adsorption dryer according to one of the aspects described above. Therefore, the compressed gas system benefits from the advantages already described above for adsorption dryers or methods for drying.

[0104] Of particular advantage is the synergistic effect achieved by using the waste heat of the compressor to heat the heating zone of the adsorption dryer, where the waste heat of the compressor can be advantageously used in the adsorption dryer. Attached Figure Description

[0105] The invention will now be described in detail below with reference to the accompanying drawings and embodiments.

[0106] Figures 1a to 1e Compressed gas systems with adsorption dryers are shown for different process steps.

[0107] Figures 2a to 2e A compressed gas system with an adsorption dryer is shown according to another embodiment for different method steps.

[0108] Figures 3a to 4b The different heat transfer sections of the heat exchanger are shown. Detailed Implementation

[0109] Figure 1a A compressed gas system 100 is shown in the schematic diagram. The compressed gas system 100 has a compressor 1 and an adsorption dryer 102. The compressor 1, which can also be referred to as a compressor, works in conjunction with an oil cooler 2, an oil separator 3, and a compressed air cooler 4, which will be described in more detail below. The compressor 1 supplies compressed air to the adsorption device 102, which is supplied between two valves 5 and 6.

[0110] The adsorption dryer 102 has two pressure vessels 7 and 8, which can also be simply referred to as containers. Specifically, these two pressure vessels 7 and 8 operate alternately, such that one pressure vessel operates in drying operation and the other in regeneration operation. For this purpose, compressed gas for drying in the drying operation can be correspondingly supplied to one of the two containers 7 and 8 by correspondingly providing valves 5 and 6.

[0111] Each of the two containers 7 and 8 has an upper portion 7a or 8a and a lower portion 7b or 8b, respectively. Both containers are filled with an adsorbent material, which is shown as a granular material.

[0112] The two containers 7 and 8 each have a drying inlet 103 or 104 and a drying outlet 105 or 106. In the illustrated embodiment, the drying inlets 103 and 104 are thus located at the bottom, while the drying outlets 105 and 106 are located at the top. Therefore, during drying operation, the compressed air to be dried flows from bottom to top, while the regenerated air flows from top to bottom.

[0113] The corresponding lower portions 7b or 8b of containers 7 or 8 can be heated by means of heating devices 16 or 17, which thus respectively form heating devices. Therefore, if compressed air flows in from the drying inlet 103 or 104, the compressed air first flows through the heating zone, which is shut off during drying operation, and then flows through the upper portion 7a or 8a. During regeneration operation, regeneration air flows from top to bottom, that is, flows in at the drying outlet 105 or 106, first through the upper portion 7a or 8a, and then through the lower portion 7b or 8b, which can accommodate or form the heating zone. During regeneration operation, heating devices 16 or 17 are respectively in operation.

[0114] During drying operation, the dried compressed air flows out from either drying outlet 105 or drying outlet 106, depending on which of the two containers 7 and 8 is operating during the drying operation, and essentially flows to valve 12, which may also be called the outlet valve, and from there to dryer outlet 13, i.e., generally to the outlet of adsorption device 102. However, additional containers with adsorbent material may also be connected to compensate for fluctuations in the humidity of the dried compressed air, as proposed in one embodiment, but not shown here for simplicity.

[0115] Simultaneously, a portion of the dried compressed air is guided through throttle valves 10 and 11 before valve 12, one or both of which reduce the pressure of the dried compressed air, particularly to approximately ambient pressure. Which of the two throttle valves 10 or 11 reduces the pressure, or to what extent, depends on which of the two containers 7 and 8 is in drying operation and which is in regeneration operation. In any case, a portion of the dried compressed air is guided from the container operating in drying operation to the container operating in regeneration operation via the two throttle valves 10 and 11, controlled by valve 9 located between them.

[0116] Therefore, the container operating during regeneration receives regenerated air at the drying outlet 105 or 106, which flows through the corresponding container 7 or 8, where the flow can be considered as the lower portion 7b or 8b of the heating zone, and finally exits at the drying inlet 103 or 104. From there, the regenerated air can be discharged into the environment via valve 18 or 19 and a downstream silencer 20 or 21.

[0117] Therefore, a feasible implementation is presented in a simplified form in Figure 1a As shown in the diagram, air is compressed in compressor 1. Here, oil cooled in oil cooler 2 is injected into the compressor. The warm compressed air-oil mixture is separated in oil separator 3. The compressed air flows from the oil separator through compressed air cooler 4 and is cooled there.

[0118] Similarly, the temperature or temperature level of the oil can be increased by guiding all or part of the oil past the oil heat exchanger 2 of the compressor in a bypass sense, thereby delivering it to the compressor block at a higher temperature.

[0119] According to Figure 1b In the diagram, container 7 is exemplarily used for drying, and container 8 is used for regeneration. Valves 5, 9, and 19 are open, and valves 6 and 18 are closed. Three-way valve 12 connects container 7 to drying outlet 13.

[0120] Compressed air flows through container 7 via valve 5 and is dried there. Most of the moisture removed from the compressed air is absorbed by a desiccant in the lower portion 7b of the container, where a heating device 16 is located. When container 7 is used for drying, the heating device 16 is not activated, so the material to be dried is not heated. Most of the dried compressed air flows to the drying outlet 13 via valve 12. A small portion of the dried compressed air flows from container 7 to container 8 via valve 9. The pressure is reduced to near ambient pressure via throttle valves 10 and 11 to generate the largest possible volume of regenerated air. The depressurized air absorbs water from the material to be dried in container 8 and exits the container via valve 19 and silencer 21.

[0121] The drying material in the lower portion 8b of the container 8 is heated by the heating device 17. In this container portion, i.e., the lower portion 8b, most of the water has been bound during the previous drying process. Heating the drying material enhances water desorption, and by heating the air, a larger amount of water vapor can be transported from the container per unit mass of air. Therefore, a much smaller amount of regeneration air is required compared to a cold-regeneration adsorption dryer. Thus, according to... Figure 1a , Figure 1b and Figure 1c This method is significantly more efficient than similar methods to date. Figure 1cIn the reverse operation, container 8 is used for drying, and container 7 is used for regeneration.

[0122] To further reduce the amount of regeneration air, valve 9 can remain closed at the start of regeneration until the dry material in zone 8b is sufficiently heated by heating device 17, so that regeneration can proceed efficiently from the start of the regeneration air supply. This operation... Figure 1d As shown in the image.

[0123] Compared to typical adsorption dryers that undergo thermal regeneration, much less heat is stored in the adsorbent material after regeneration because only a portion of the material is heated, and furthermore, due to the use of depressurized compressed air, it can operate at a lower temperature during regeneration.

[0124] To further reduce stored heat, heating device 17 can be deactivated in the final stage of regeneration, thus allowing the final stage of regeneration to proceed without a heat supply. Appropriately, the ratio of regeneration air mass to heated desiccant mass used here is in the range of approximately 0.025 kg / kg to 0.22 kg / kg. This operation... Figure 1e It is running in the middle.

[0125] exist Figure 2a This illustrates a particularly efficient implementation that utilizes waste heat from a compression process. The construction corresponds to... Figure 1a The structure has specific embodiments for heating devices 16 and 17.

[0126] Heating devices 16 and 17 can be supplied with warm oil from the compressor by opening valve 14 or 15. If neither heating device is activated, valves 14 and 15 are closed and ground valve 22 is opened instead.

[0127] Figure 2b The following operation is shown, in which container 7 is used for drying and container 8 is used for regeneration. Correspondingly, valve 15 is open, and valves 14 and 22 are closed.

[0128] Figure 2c The following operation is shown, in which container 8 is used for drying and container 7 is used for regeneration. Here, valve 14 is open, and valves 15 and 22 are closed.

[0129] Figure 2d The following operation is shown, where container 7 is used for drying, and container 8 is preheated at the start of regeneration. Correspondingly, valve 15 is open here, and valve 9 remains closed.

[0130] Figure 2e The following operation is shown, in which container 7 is used for drying, and container 8 is not heated in the final part of regeneration. Correspondingly, valve 15 is closed here, while valve 9 remains open.

[0131] Figures 2a to 2e The embodiments illustrate an advantageous, compact combination of compressor 1 and dryer. However, it is not necessary for the dryer to be directly coupled to the compressor. In particular, multiple compressors may supply compressed air to one dryer, one compressor may supply compressed air to multiple dryers, or multiple compressors may supply compressed air to multiple dryers. To transfer heating power from the compressor to the dryer, an alternative heat transfer medium may be used instead of compressor oil. To optimize the process, the heat transfer medium may also be additionally heated, for example by means of an electric heating device, to a temperature level above which waste heat is available.

[0132] Other aspects or further descriptions of the invention are mentioned below.

[0133] In a further description, it is assumed that the container flows upwards during drying and downwards during regeneration. However, other installation locations are equally feasible.

[0134] Therefore, the core aspect of this invention is:

[0135] - A method using a cold-regeneration adsorption dryer.

[0136] - During regeneration operation, heat is transferred only to the lower part of the container via a heating device.

[0137] Advantageously, existing waste heat, such as the heat contained in the oil of a screw compressor, can be used for the heating device. Hot water can also be used in facilities with water cooling systems. Other heat sources advantageously available near the dryer can also be used. The method can also be carried out using an electric heating device.

[0138] The heated lower portion of the container accounts for approximately 20% to 70% of the total container.

[0139] Compared to heating the air first, and then using the air to heat the desiccant and desorb the water, direct heating offers the feasibility of delivering more heat per unit volume of air. This reduces the amount of regenerated air required. The amount of regenerated air can be further reduced by first heating the drying material without cross-flow, and then guiding the regenerated air through the container to be regenerated.

[0140] Because dry air is used for regeneration, the required temperature is not as high as that of dryers that regenerate using heated ambient air. Therefore, existing low-temperature waste heat can be utilized.

[0141] In one embodiment, hot oil from a screw compressor with an oil injection device is used for heating during regeneration. The oil typically has a temperature between 60°C and 100°C.

[0142] Because the dried material is directly heated, the regenerated air is used only to transport the desorbed water vapor. The amount of regenerated air can be further reduced by lowering the pressure during regeneration. The lower the regeneration pressure, the less compressed air needs to be depressurized to produce the required volumetric flow rate.

[0143] Figure 3a , Figure 3b , Figure 4a and Figure 4b Pressure vessels with heating zones having different or different configurations are shown. For better comparability, the same reference numerals are used in the accompanying drawings to denote elements or areas that are not necessarily the same. In particular, all four figures show a pressure vessel 300 with adsorbent packing 302, i.e., packing of particularly granular adsorbent material, and a heating zone 304 with a heat exchanger 306, which is symbolically shown. The adsorbent packing 302, i.e., the area in which it is located, is shaded with dotted lines. The heating zone 304 is outlined by a dashed line and is also shaded with a dashed line. Thus, the heating zone 304 is located in the area of ​​the adsorbent packing 302, which is indicated by the superimposed shading lines. Similarly, for the sake of scale, the vessel height h is drawn in all four figures. A drying inlet 322 and a drying outlet 324 are also drawn in all four figures.

[0144] It should be mentioned that heat exchanger 306 is symbolically drawn in the figures. The heat exchanger extends over the entire cross-section of the adsorbent packing 302. In particular, but not exclusively, the pressure vessel and the corresponding adsorbent packing may have a cylindrical cross-section, over which heat exchanger 306 extends entirely. Figure 3a , Figure 3b , Figure 4a and Figure 4b The purpose is to specifically describe the different extensions in the flow direction, i.e., the height h direction, for heat exchanger 306.

[0145] The heating region 304 of the heat exchanger 306 roughly corresponds in size to the structural space of the heat exchanger 306. An adsorbent, also synonymously referred to as an adsorbent material, is also present here. Therefore, the heat exchanger 306 is surrounded by an adsorbent.

[0146] There are essentially implementations of adsorption dryers that do not have a sieve bottom or perforated plate at the lower end of the pressure vessel 300. In these implementations, the adsorbent packing material, or simply packing material, is placed directly on the bottom of the vessel.

[0147] Figure 3a and Figure 3b This pressure vessel is shown. Figure 3aIn the heat exchanger, due to its structural design, the heating zone 304 begins at approximately 2% of the container height h and extends to approximately 30% of the container height h. The container height h is the length from the drying inlet to the drying outlet.

[0148] exist Figure 3b In the heat exchanger, due to its structural design, the heating zone 304 begins at approximately 2% of the container height h and extends to approximately 60% of the container height h. Here, in... Figure 3a and Figure 3b In this context, the dry section 326 extends along the entire height h. Here, the dry section is illustrated only by arrows indicating its length. In practice, the dry section extends within the pressure vessel 300, i.e., within the adsorbent packing 302. The same applies to what will be further explained below. Figure 4a and Figure 4b Dry section 426. Basically, the area defined by the adsorbent filler 302 is dry section 326 or 426.

[0149] Furthermore, some implementations of adsorption dryers include a sieve bottom, perforated plate, etc., in the lower region of the pressure vessel, referred to herein as a staggered bottom section 308. This staggered bottom section is slightly spaced from the bottom of the pressure vessel and has sufficiently small pores to prevent adsorbent particles from passing through, while allowing process air to pass through. Therefore, the adsorbent packing is placed on the staggered bottom section 308, which can be, for example, a sieve bottom. As a result, after the process air flows in from the bottom, it can be distributed in the space below the staggered bottom section 308 before flowing upwards through the packing. Advantageously, if condensate is not 100% separated after the heat exchanger, the condensate or liquid water can accumulate below the sieve bottom at the bottom of the vessel when it enters the bottom of the vessel with the compressed air. Thus, the adsorbent is not in "liquid water."

[0150] This embodiment, having staggered bottom segments 308, in Figure 4a and Figure 4b As shown in [the text]. Therefore, in [the text] Figure 4a and Figure 4b In the middle, dry section 426 does not extend over the entire height h.

[0151] Figure 4a A pressure vessel 300 is shown, having a staggered bottom section 308, which may be configured as a sieve bottom or an orifice plate, and the staggered bottom section 308 is located at approximately 3% of the vessel height h. Due to the structure-determined heat exchanger, a heating zone 304 begins at approximately 5% of the vessel height h and extends to approximately 30% of the vessel height h.

[0152] The packing can be compressed from above by means of, for example, an orifice plate 310 with a pressure spring 312, so that when the flow direction is changed by compressed gas, i.e., the flow is reversed, particle movement or agitation is impossible. This provides protection against mechanical wear of the particles. Here, the particles extend to approximately 92% of the container height h.

[0153] Figure 4b A pressure vessel 300 is shown, having a staggered bottom section 308, which may be configured as a sieve bottom or an orifice plate, and the staggered bottom section 308 is located at approximately 3% of the vessel height h. Due to the structure-defined heat exchanger, a heating zone 304 begins at approximately 5% of the vessel height h and extends to approximately 60% of the vessel height h.

[0154] Here, the packing can also be compressed from above by means of, for example, an orifice plate 310 with a pressure spring 312, so that when the flow direction is changed by compressed gas, i.e., the flow is reversed, particle movement or agitation is impossible. This provides protection against mechanical wear of the particles. Here, the particles extend to approximately 92% of the container height h.

Claims

1. Method for drying compressed gas, in particular compressed air, with a sorption dryer, which has at least one pressure vessel with an adsorbent material for adsorbing moisture from the compressed gas, wherein - in a drying operation for drying the compressed gas, the compressed gas flows through the pressure vessel along the adsorbent material from a drying inlet through a drying path to a drying outlet and flows out as dried compressed gas, - in a regeneration operation for regenerating the adsorbent material, a regeneration gas flows through the pressure vessel along the adsorbent material from the drying outlet through the drying path to the drying inlet and extracts moisture from the adsorbent material there, and - in the regeneration operation, partial heating is carried out in a heating region in the pressure vessel, wherein - the heating region is provided only in a partial region of the pressure vessel adjacent to the drying inlet.

2. Method according to claim 1, characterized in that - the heating region is provided in a section of the drying path of 0% to 80%, preferably 0% to 60%, in particular 0% to 50%, measured from the drying inlet to the drying outlet, and / or - the heating region extends over at least 20% of the drying path, preferably at least 30% of the drying path, in particular at least 40% of the drying path, preferably at most 70% of the drying path, in particular at most 60% of the drying path, and especially - no heating or reduced heating is carried out outside the heating region, wherein the energy input per volume is less than 30% compared to the heating region.

3. Method according to claim 1 or 2, characterized in that - as part of the dried compressed gas, a compressed gas fraction is used as regeneration gas, - the compressed gas fraction at the drying outlet is introduced into the pressure vessel, and - the compressed gas fraction is subjected to a pressure reduction when or before being introduced into the pressure vessel.

4. Method according to any of the preceding claims, characterized in that - the heating is carried out in the pressure vessel by means of a heat exchanger, wherein - a heat transfer section of the heat exchanger is surrounded by the adsorbent material in order to output heat to the adsorbent material.

5. Method according to any of the preceding claims, characterized in that - the compressed gas is generated by a pressure generating device, in particular a compressor, and - waste heat of the pressure generating device is used for heating the heating region during the regeneration, wherein in particular - the heating region is heated during the regeneration using heating oil of a screw compressor with oil injection.

6. Method according to any of the preceding claims, characterized in that - the heating of the heating region is carried out using - one pressure generating device or waste heat of the pressure generating device and - active heating from an energy source, in particular such that - the energy source is a heat exchanger, in particular a heat exchanger of a pressure generating device, in particular a compressor, and / or - the active heating is carried out by means of a heating oil of a screw compressor with oil injection. - the temperature of the heating medium heated from the waste heat is further increased to a predetermined temperature by the active heating.

7. The method according to any of the preceding claims, characterized in that - at least two pressure vessels are used, - in combined operation, at least one of the pressure vessels works in the drying operation, while the other pressure vessel works in the regeneration operation, and - the pressure vessel working in the drying operation outputs dried compressed gas, a portion of which is tapped off as a compressed gas fraction and is fed to the pressure vessel working in the regeneration operation and serves as regeneration gas.

8. The method according to any of the preceding claims, characterized in that - upon switching from the drying operation to the regeneration operation, - the flow of compressed gas from the drying inlet to the drying outlet is first interrupted, - the heating of the heating region is then started, and - after the start of heating, a predetermined heating period is waited until the regeneration gas enters the pressure vessel.

9. The method according to any of the preceding claims, characterized in that - upon switching from the regeneration operation to the drying operation, - the heating is first ended, and - after the end of heating, a predetermined cooling period is waited until the compressed gas enters the pressure vessel, wherein in particular - after the end of heating, during part or the entire cooling period, regeneration gas continues to flow through the pressure vessel.

10. The method according to any of the preceding claims, characterized in that - compressed air is dried as compressed gas, and in particular - a portion of the dried compressed air is used for the regeneration gas, so that - regeneration air is used as regeneration gas, wherein the regeneration air flows out into the environment of the adsorption dryer after passing through the drying section.

11. The method according to any of the preceding claims, characterized in that - in the regeneration operation, the pressure in the pressure vessel is reduced below the pressure outside the pressure vessel, in particular below atmospheric pressure.

12. The method according to any of the preceding claims, characterized in that - dried compressed air flows through an additional pressure vessel having adsorption material after flowing out of the drying outlet, and the additional pressure vessel is not incorporated into the regeneration operation.

13. An adsorption dryer for drying compressed gas, in particular compressed air, and having at least one pressure vessel with adsorption material for adsorbing moisture from the compressed gas, and being prepared to carry out a method, wherein - in a drying operation for drying the compressed gas, the compressed gas flows through the pressure vessel along the adsorption material from a drying inlet through a drying section to a drying outlet and flows out as dried compressed gas, - in a regeneration mode for regenerating the adsorbent material, a regeneration gas flows along the adsorbent material through the pressure vessel from the drying outlet through the drying section to the drying inlet, and here extracts moisture from the adsorbent material, and - in the regeneration mode, partial heating takes place in a heating zone in the pressure vessel, and - the heating zone is provided only in a partial region of the pressure vessel adjacent to the drying inlet, and / or - the adsorption dryer is designed to carry out the method according to any of the preceding claims.

14. Adsorption dryer according to claim 13, characterized in that - the heating zone is provided in a section of the drying section of 0% to 80%, preferably 0% to 60%, in particular 0% to 50%, measured from the drying inlet to the drying outlet, - and extends over at least 20% of the drying section, preferably at least 30% of the drying section, in particular at least 40% of the drying section, and / or - a heat exchanger is provided in the pressure vessel for carrying out the heating, which heat exchanger - has a heat transfer section provided in the heating zone, which heat transfer section is surrounded by the adsorbent material.

15. Adsorption dryer according to claim 13 or 14, characterized in that - at least two pressure vessels are provided, and - the adsorption dryer is designed for a combined mode in which at least one of the pressure vessels works in the drying mode while the other pressure vessel works in the regeneration mode, wherein - the pressure vessels are connected to one another such that they act together, so that the pressure vessel working in the drying mode outputs dried compressed gas, a portion of which is tapped off as a compressed gas fraction and fed to the pressure vessel working in the regeneration mode and used as a regeneration gas, and / or - an additional pressure vessel with adsorbent material is provided, wherein the additional pressure vessel is connected to the remaining pressure vessels such that it is not incorporated into the regeneration mode.

16. Compressed gas system for providing dried compressed gas, having - a pressure generating device, in particular a compressor for compressing gas to the compressed gas, - an adsorption dryer having a plurality of pressure vessels filled with adsorbent material, wherein the pressure vessels each - have a drying section for drying the compressed gas, and - a heating zone which extends only over a portion of the drying section, wherein a heat exchanger is provided which is connected to the compressor for heating the heating zone in order to heat the heating zone by means of waste heat from the compressor, wherein - in particular an adsorption dryer according to any of claims 13 to 15 is used.

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