AIR COMPRESSION AND DRYING APPARATUS AND ITS METHOD OF USE

Description

Apparatus for compressing and drying air and its method of use The present invention relates to a compression and drying apparatus of the air, especially of the type comprising an adsorption dryer. 5 The use of compressed air is required by numerous applications and, in various contexts, it is desirable that its humidity is kept as low as possible. Dry compressed air reduces the risk of corrosion damage in the pneumatic system and improves the operation of connected tools and machinery. There are many known solutions for drying compressed air, such as 10 example that described in the Korean patent KR2509455B1 which describes a dehumidification system with two units working alternately in one operational phase and a regeneration phase. The solution described in the document provides an air compressor upstream of the dehumidifier to facilitate drying the air by promoting the condensation of the water vapor present. 15 Korean patent KR1505879B1 concerns a drying apparatus for laundry dryers and requires the presence of a compressor upstream of the air dryers to improve the energy efficiency of the process. Japanese patent application JP62001434A describes a system of dehumidification and O2 generation. The two processes are carried out with devices 20 distinct and in sequence. Disadvantageously, some types of systems require humid air to be introduced into the compressor that must both compress the air and dehumidify it. This determines the need to cool the compressor by providing a cooling circuit dedicated cooling, with the associated energy costs. 25 Other types of systems involve drying under pressure, consequently requiring the presence of pressurized tanks. Again, keeping pressurized tanks and usually Cooling the air coming out of the compressor causes energy costs that affect significantly on the efficiency of a compressed air system. 5 Some systems, which make use of a compressor, are made to generate nitrogen and / or oxygen under pressure, e.g. oxygen to be disposed of in cylinders for medical use, or the nitrogen used to slow down the spoilage of packaged foods in food processing plants. In such cases, further problems arise in addition to the above. 10 described. The main disadvantage of this type of system is related to the need to use filters for the generation of compressed nitrogen or oxygen. Another disadvantage is the need to compress the entire volume of air in compressor inlet to then use only a portion of it (N2 or O2), with a 15 consequent energy expenditure. A further disadvantage is the need to provide separate devices for drying and generation of O2 or N2, resulting in higher losses of load. In the context of these needs, the Applicant has therefore noted the need for 20 optimize the systems or equipment for air compression, reducing their energy costs associated with known solutions. A further need felt by the Applicant is also linked to the possibility of reduce the size and costs associated with solutions that require the combination with filters for the generation of compressed nitrogen or oxygen. 25 Therefore, the problem underlying the present invention is to provide a air compression apparatus which allows to overcome, at least in part, to one or more of the drawbacks complained of with reference to the cited prior art. An object of the present invention is to provide an apparatus for the air compression in which it is possible to reduce energy and space costs 5 of the apparatus itself, allowing the manufacturer to make more profit from reinvest in his business. It is also an object of the invention to provide an apparatus for compressing air which achieves the above purpose by being easy to build and adaptable to the standard elements of existing systems, so that they can be integrated into these 10 last by retrofitting them. According to a first aspect of the invention, this problem is solved and one or more of these goals are at least partly achieved by a compression apparatus and air drying including: - a compressor; 15 - an air treatment device comprising a dryer adsorption, including a hygroscopic material; wherein said air handling device is preferably arranged to upstream of said compressor, with respect to a direction of air flow between a input and an output of said apparatus. 20 Preferably, said air compression and drying apparatus comprises a control unit configured to operate said air treatment device alternately in two different conditions operational, which include an adsorption operating condition, in which said hygroscopic material absorbs the humidity present in the air, and a condition 25 regeneration operation, in which said hygroscopic material releases water adsorbed. The main advantage of the invention is the presence of the treatment device of the air upstream of the compressor, allowing the introduction of already dry air inside the compressor, reducing wear and tear caused by humid air, and 5 optimize the air compression system, reducing energy costs linked to a refrigeration system of a possible refrigeration dryer and / or a pressurized circuit for any adsorption dryers. A further advantage of the invention is the use of an adsorption dryer. which avoids complicating the apparatus with refrigeration circuits. 10 According to some preferred embodiments of the invention said apparatus comprises at least one first and at least one second air treatment device, each comprising a respective absorption dryer including a respective hygroscopic material. Preferably, said control unit operates, alternatively, said first 15 air treatment device in said adsorption operating condition, in which said hygroscopic material absorbs the humidity present in the air, and said second air treatment device in said operating condition of regeneration, in which the hygroscopic material releases the absorbed water. Advantageously, this configuration, with said at least one first and at least 20 a second air treatment device in parallel fluid dynamics, allows you to produce compressed air continuously without ever having to block the apparatus for carrying out the regeneration of hygroscopic material. Preferably, said air treatment device comprises an opening air inlet and a pre-filter at least at said opening, where 25 said pre-filter is positioned in an inlet portion of said device treatment, in which the air inlet opening is defined. The treatment device may also comprise a first chamber communicating with said entrance portion and in which said material is positioned hygroscopic. 5 Said treatment device may further comprise a valve in correspondence of an air outlet opening located downstream of the said first one room. Advantageously, the described configuration includes a device compact treatment that includes both the pre-filter for preliminary cleaning 10 of the air, from dust, particulate matter, etc., both the hygroscopic material suitable for dehumidify the air, resulting in dry, clean air coming out. Preferably, said treatment device comprises at least one filter configured for the generation of N2 or O2 through which an air flow passes between said inlet opening and said outlet opening. 15 Therefore, another advantage associated with this feature is the reduction of bulk and costs due to multiple devices for drying and any generation of pure gases such as O2 and N2. According to some preferred embodiments, said treatment device comprises a second room, communicating with the said first room and in which is positioned 20 said at least one air filter. Preferably, said apparatus comprises a cooling circuit of said compressor and said air treatment device comprises a heat exchanger configured in such a way as to be traversed by a fluid heat transfer medium coming from said cooling circuit, so as to 25 heating said hygroscopic material when said treatment device operates in said operating condition. Advantageously, the heat transfer fluid used to cool the compressor during its operation it is used to heat the device treatment in the operating condition of regeneration of the hygroscopic material, 5 with a view to saving energy in the system. Preferably, said heat exchanger is arranged to contact said first chamber or so-called first and second chamber. In this way the heat transfer fluid also helps to regenerate said at least an air filter optimizing energy consumption. 10 Furthermore, said treatment device may comprise a fluid container hot placed in contact with said first chamber or said first and second chamber, said container for hot fluids being capable of regenerating said material hygroscopic or said hygroscopic material and said at least one air filter. Advantageously, the presence of said container for hot fluids allows for 15 accelerate the regeneration operating condition when working in combination with said heat exchanger, or in the absence of said heat exchanger regenerates said hygroscopic material and / or said air filter during the condition regeneration operation using the heat transfer fluid used for cool the compressor. 20 According to some preferred embodiments of the invention said device treatment includes a suction channel connected to a vacuum pump, said vacuum pump being suitable for creating a vacuum inside said first chamber or within said first and said second chamber, wherein said control unit operates said vacuum pump in said regeneration operating condition. 25 Combining the vacuum pump with the heat exchanger and / or container for hot fluids speed up the regeneration operating condition. According to some preferred embodiments of the invention, said dryer absorption includes a desiccant dehumidifying wheel comprising a hygroscopic material, called a desiccant dehumidifying wheel which includes a 5 rotating body in which are defined, alternatively, an operating portion of adsorption aimed at adsorbing the humidity present in the air and, a portion regeneration operation in which the hygroscopic material releases water absorbed. Advantageously, using said desiccant dehumidification wheel allows 10 not to interrupt the production of compressed air without having to foresee at least two treatment devices, but using only one, having the portion regeneration operational portion that regenerates while the operational portion of adsorption adsorbs moisture from the air. The treatment device, preferably when it includes the wheel of 15 desiccant dehumidification, may also comprise said at least one filter of the air for the generation of N2 or O2. In this embodiment, the air filter can be realized as a filter wheel comprising, at the same time, an operating portion designed to filter the air to generate O2 or N2 and, a regeneration portion where the filter is regenerated from particles 20 adsorbed. Advantageously, the configuration with the air filter for the generation of N2 o O2 made as a filter wheel allows the use of only one device treatment and not to interrupt the production of compressed air during the regeneration operating condition. 25 Preferably, said air treatment device comprises a circuit auxiliary device to allow the passage of dry air in said operating condition regeneration, called dry air with flow direction opposite to the humid air entering the said operational regeneration phase. Advantageously, the presence of an auxiliary circuit means that you do not have to 5 use the main system circuit, being able to size it ad hoc minimizing energy consumption. In a second aspect, the present invention relates to a method of air treatment comprising a compressor and a device air treatment. 10 Preferably, the method provides for the provision of at least one device air treatment placed upstream of said compressor, with respect to a direction of air flow between an inlet and an outlet of said apparatus, and comprising an adsorption dryer including a hygroscopic material and, a heat exchanger traversed by a heat transfer fluid coming from a 15 cooling circuit of said compressor. Once the air treatment device has been set up, the air can be aspirated. with the said compressor making it flow first into the treatment device and then in said compressor to dehumidify the air, in an operating condition of adsorption, in which the hygroscopic material adsorbs the moisture present 20 in the air until the material itself is saturated. The method also involves regenerating the said hygroscopic material, in a operating condition of regeneration in which said hygroscopic material releases the adsorbed water during said adsorption operating condition, by making said heat transfer fluid flow at a regeneration T and being said 25 heat transfer fluid in contact with a first chamber containing said material hygroscopic, so that the water vapour contained in the material evaporates hygroscopic and let it flow out of a drain opening. By regeneration T we mean a temperature that facilitates the condition regeneration operation, promoting and / or speeding up the evaporation of water 5 contained in the hygroscopic material and / or gases retained in the air filter. The main advantage of the method of using the said apparatus for compression of the air is the use of the heat transfer fluid for the regeneration of the material hygroscopic, in which the heat transfer fluid absorbs heat in the cooling phase compressor cooling and releases it in the operating condition of 10 regeneration of the hygroscopic material, thus resulting in savings energetic. Another advantage of the invention lies in its simplicity of construction, and in the possibility of integrating the said device into an air compression system pre-existing by refitting the system. 15 Preferably, this method involves setting up a compression apparatus of the air comprising at least a first and at least a second device treatment placed fluid-dynamically in parallel and each including a respective hygroscopic material. Furthermore, the method provides for dehumidifying the air, in said operating condition of 20 adsorption, with said at least one first treatment device and simultaneously regenerating said hygroscopic material of said at least one second treatment device, in said regeneration operating condition. Finally, the method provides for alternating the said adsorption operating condition and said operating condition of regeneration between said at least one first and said 25 at least one second air handling device. Advantageously, this method allows the production of compressed air in continuous without having to interrupt the production process, optimising the compressed air production in terms of time. When a single treatment device is used, after having 5 dehumidified the air, the method preferably involves turning off the said compressor by interrupting the air flow; and after having regenerated said hygroscopic material, plans to reactivate the compressor. According to some preferred embodiments, wherein said treatment device comprises at least one air filter for the generation of N2 or O2, the method 10 comprises, during the dehumidification of the air, generating a passage of air downstream or upstream of the hygroscopic material in said air filter, so as to generate N2 or O2 at the inlet of said compressor and, during the regeneration of the hygroscopic material, flow a heat transfer fluid, at a regeneration T, in contact with a second chamber containing said air filter. 15 In this way the method allows to dehumidify the air and generate O2 or N2 at the same time and regenerate the hygroscopic material and the air filter at the same time, optimizing regeneration and absorption times and filtering. Please note that the preferred aspects illustrated above in relation to an aspect can 20 find similar application also in further aspects of the invention. These features and the benefits associated with them will be even better evident from the detailed description of some favorite examples of realization of the invention which will be illustrated, for indicative and non-limiting purposes, with reference to the attached drawings in which: 25 Figure 1 is a schematic representation of a compression apparatus of the air according to the invention; Figure 2 is another schematic representation of an apparatus for the compression of air according to the invention in a second embodiment; Figure 3 is a further schematic representation of an apparatus for the 5 air compression according to the invention in a further embodiment; Figure 4 is a perspective view of an air handling device included in said apparatus according to the invention; Figure 5 is a perspective view of a preferred embodiment of the device. figure 4; and 10 Figure 6 is a schematic representation of a preferred embodiment of said apparatus. With reference to the figures, a preferred embodiment of an apparatus for compressing air globally indicated by the reference numeric 1. 15 The air compression apparatus 1 comprises a compressor 2 and a air treatment device 3. Said air treatment device 3 is arranged upstream of said compressor 2, with respect to a direction of air flow between an inlet 1a and an outlet 1b of said apparatus 1, and comprises an absorption dryer 4, 20 which in turn comprises a hygroscopic material 5. The apparatus 1 also comprises a control unit 25, illustrated for example in figure 4, configured to operate the treatment device of the air 3 alternatively in two different operating conditions, which include an adsorption operating condition, in which said hygroscopic material 25 5 absorbs the humidity present in the air, and an operating condition of regeneration, in which said hygroscopic material 5 releases the absorbed water. The main advantage of the present invention lies in the arrangement of the device air treatment 3 upstream of compressor 2, so as to introduce dry air in compressor 2 itself, reducing wear due to humid air, without the 5 need to resort to a refrigeration system, with consequent savings economical in terms of energy. As shown in figures 4, 5 and 6 the air treatment device 3 can comprise an air inlet opening 7 and a pre-filter 8 at least in correspondence of said opening 7. Advantageously, the pre-filter 8 is positioned 10 in an inlet portion 7a of said treatment device 3 and is suitable for removal of unwanted particles and / or oil particles. According to some embodiments, such as those shown in the figures, the opening of input 7 comprises a closing element 24 comprising a plurality of holes. 15 Preferably, to control the opening and closing of the inlet opening 7, the treatment device 3 comprises an inlet valve 26 and a respective pneumatic actuator 27 controlled by said control unit 25. According to some embodiments of the invention the apparatus 1 comprises at least one first 3a and at least one second 3b air handling device, each of which 20 comprises a respective absorption dryer 4a, 4b including a respective hygroscopic material 5a, 5b. It will be appreciated that the control unit 25 operates, alternatively, the first air treatment device 3a in said operating condition of adsorption, in which the hygroscopic material 5a absorbs the moisture present 25 in the air, and operates the second air treatment device 3b in said regeneration operating condition, in which the hygroscopic material 5b releases the absorbed water. Advantageously, this configuration with two devices 3a, 3b in parallel allows for the continuous production of compressed air without ever having to block plant 1 to regenerate the material 5 hygroscopic 5a, 5b. Preferably, the two devices are arranged in fluid-dynamic parallel along the plant line 1 and the flows are controlled by a group of valves 6a, 6b properly operated. In the example of the embodiment of figures 5 and 6 the valve group 6a, 6b 10 includes a three-way valve 6. According to the achievements that include a first treatment device of air 3a and a second air treatment device 3b, each device comprises a first inlet valve 26a and a second one respectively inlet valve 26b which operate alternately in opening and closing, 15 allowing the absorption operating condition to take place in the first air treatment device 3a and, at the same time, the performance of the regeneration operating condition in the second treatment device of air 3b, or vice versa. The air treatment device 3 may further comprise a first chamber 20 9 communicating with said input portion 7a and in which the material is positioned hygroscopic 5, in said operating condition of adsorption and to release it, in said regeneration operating condition. Preferably, the pre-filter 8 has a toroidal shape that develops around the first chamber 9 making a compact device 3. 25 The treatment device 3 may further comprise a valve 6 in corresponding to an air outlet opening 10. According to preferred embodiments of the invention the treatment device includes at least one air filter 11 for generating N2 or O2. Therefore, an advantage of the present invention is that it provides a single 5 device 3 that includes both the dryer and air filter function for the generation of O2 or N2, in order to reduce the space required in a plant line 1 and the services of the different devices 3, with a consequent economic saving in terms of space and energy. In order to be able to arrange the air filter 11 for the generation of O2 or N2, the device 10 treatment room preferably comprises a second communicating chamber 12 with said first chamber 9 and in which the at least one air filter 11 is positioned. Preferably, the first chamber 9 and the second chamber 12 are separated by a perforated septum 21, insertable between the first 9 and the chamber 12 once the hygroscopic material 5 or the air filter 11. 15 Preferably, the air treatment device 3 comprises a circuit auxiliary 13 designed to allow the passage of dry air in the operating condition regeneration, called dry air with flow direction opposite to the humid air entering the adsorption operating condition. To allow said auxiliary circuit 13 to operate, said apparatus 1 for the compression of the air 20 may include a fan 14 that blows dry air into the device 3. For example, in the embodiment of the invention in Figure 2, while said first treatment device 3a is in the adsorption operating condition, a first valve 6a is open, allowing airflow between the first device treatment 3a and compressor 2 and a second valve 6b is closed, preventing 25 an air flow between the second treatment device 3b and the compressor 2. Furthermore, a valve C included in said auxiliary circuit 13 is closed, preventing the release of water from said hygroscopic material 5 in the form of water vapor, while a valve D is open, allowing the flow of a portion of dry air, produced in the first device 3a, in the second device 3b, 5 promoting the regeneration operating condition. Alternatively (figure 3), part of the compressed dry air is directed towards said treatment device 3 in a portion of the plant 1 fluid-dynamically isolable and, when in regenerative operating condition, a valve E is opened which allows the expansion of the compressed air in said 10 treatment device 3. Furthermore, in order to save energy of the device 1, the device treatment 3 may comprise a heat exchanger 14 through which a fluid flows heat transfer medium coming from a cooling circuit 15, preferably, of called compressor 2, with the function of regenerating the hygroscopic material 5. The 15 heat exchanger 14 may be arranged in contact with said first chamber 9 or with the said first 9 and second 12 chamber, when the latter is present. Preferably, the heat transfer fluid is oil, alternatively it is hot air. In this way, the heat transfer fluid used to cool the compressor 2 during its operation it is used to heat the device 20 treatment 3 in the operating condition of regeneration of the hygroscopic material 5, with a view to saving energy in plant 1. Preferably, the treatment device 3 comprises a sensor temperature 22, set up to monitor the fluid temperature heat transfer medium fed into the treatment device 3. Furthermore, the treatment device 25 treatment 3 may comprise a container 16 for hot fluids, also known as a heater, placed in contact with said first 9 chamber or said first 9 and second chamber 12. The container 16 for hot fluids is designed to regenerate the material hygroscopic 5 or the hygroscopic material 5 together with the air filter 11. The possible combined action of the increase in temperature due to the presence 5 of the heat exchanger 14 and / or the container 16 for hot fluids and air dry introduced into the treatment device 3, allow to regenerate the hygroscopic material 5 or hygroscopic material 5 together with air filter 11 for the generation of O2 or N2. A further embodiment of the invention provides that the treatment device 10 3 includes a suction channel 17 connectable to a vacuum pump 18 included in said apparatus 1. The vacuum pump 18 is advantageously suitable to create a vacuum inside the first chamber 9 or inside the first 9 and the second 12 chamber, to facilitate the regeneration of the hygroscopic material 5 and / or the filter of the air 11.As shown in figure 4, 5 and 6 the air treatment device 15 may include an actuator, not shown in the figure, which acts on the valve 6 at the air outlet opening 10. The actuator opens the valve 6 during the absorption operating condition allowing the air flow sucked by compressor 2. During the regeneration operating condition, the actuator deactivates and valve 6 is closed, but leaving the opening of 20 entrance 7 open to allow evaporation of the water adsorbed on the material hygroscopic 5 and the desorption of particles adsorbed on the air filter 11 for the generation of O2 or N2 transported by the convective motion of the dry air introduced through auxiliary circuit 14. According to some designs not shown in the figure, the absorption dryer 25 4 comprises a desiccant dehumidifying wheel including, at the same time, an adsorption operating portion capable of absorbing the humidity present in the air and, a regeneration operating portion in which the water absorbed on it and evaporated. Advantageously, this configuration of the invention allows to avoid the 5 configuration with two devices 3 in parallel fluid dynamics and ensures however the continuity of the system 1, simultaneously carrying out the adsorption and regeneration operating conditions. Furthermore, said treatment device 3 may comprise at least one filter of the air 11 for the generation of N2 or O2 and wherein said air filter 11 is made 10 as a filter wheel comprising, at the same time, a portion adsorption operation designed to filter air to generate O2 or N2 and, a portion regeneration operation in which the filter is regenerated from the absorbed particles. Preferably, the filter wheel is coupled with the dehumidifying wheel desiccant, allowing the use of a single drying device 3 and 15 generation of O2 or N2 upstream of a compressor 2 along the line of the apparatus 1 for the generation of compressed air. It will be appreciated that the present invention also relates to a method of operation of an air compression apparatus 1 comprising a compressor 2 and an air treatment device 3. 20 The method involves setting up at least one air treatment device 3 placed upstream of compressor 2, with respect to one direction of air flow between an input and an output of said apparatus 1. The method also provides for use an absorption dryer 4, which in turn includes a hygroscopic material 5 and a heat exchanger 14 through which a fluid flows 25 heat transfer fluid coming from a cooling circuit 15 of compressor 2. Once the air treatment device 3 has been set up, it is possible to aspirate the air with said compressor 2 by making it flow first into the device 3 of treatment and then in compressor 2 to dehumidify the air, in an operational phase, through said hygroscopic material 5 until the material itself is saturated. 5 Preferably, in order to be able to identify the saturation of the hygroscopic material 5, the treatment device 3 comprises one or more humidity sensors connected to the control unit 25 which detects the humidity value measured by the sensors and, when this value exceeds a predetermined threshold, called control unit 25 interrupts the adsorption operating condition of the device. 10 In fact, the method involves regenerating the hygroscopic material 5, in a condition regeneration operation, by making the heat transfer fluid flow at a temperature Regeneration T around the first chamber 9 containing the hygroscopic material 5, so as to evaporate the water vapor contained in the hygroscopic material 5 and let it out from the drain opening 20. 15 According to the embodiments comprising the vacuum pump 18, the opening of exhaust 20 is in correspondence with the vacuum pump 18, as visible in figure 5. Alternatively, the exhaust opening 20 could coincide with the valve input 26, which in the regeneration operating condition allows the release of water vapor. 20 Preferably, said regeneration temperature is between 60°C and 100°C, more preferably between 65°C and 90°C, preferably 70°C. If the apparatus comprises only one treatment device 3, the method may plan to turn off compressor 2 by interrupting the air flow and, after having regenerated the hygroscopic material 5, to reactivate the compressor 2. 25 According to the embodiments wherein the air compression apparatus 1 comprising at least one first 3a and at least one second 3b treatment device placed fluid-dynamically in parallel and each including a respective material hygroscopic 5a, 5b, once set up, the method involves dehumidifying the air, in the adsorption operating condition, with the first treatment device 5 and, at the same time, regenerate the hygroscopic material 5 of the second treatment device 3b, in said regeneration operating condition. The method also provides for alternating the said adsorption operating condition and said operating condition of regeneration between said first 3a and said second 3b air treatment device. 10 Advantageously, this realization allows for continuous production of compressed air. Preferably, if the treatment device 3 comprises at least one filter of air 12 for the generation of N2 or O2, the method comprises, during the dehumidification operating condition, a passage of air downstream or upstream 15 of the hygroscopic material in said air filter 12, so as to generate N2 or O2 at the entrance to compressor 2. Furthermore, in the regeneration operating condition the method may provide for flow the heat transfer fluid, at the regeneration temperature, in contact with the second chamber 12 containing the air filter 11, so as to regenerate it before a 20 new desorption operating condition. Preferably, to be able to identify the saturation of the air filter the device 3 air treatment includes connected N2 or O2 concentration sensors with the control unit 25 suitable for regulating the operating and regeneration phase also of the air filter 11. 25 To the above-described apparatus for generating compressed air and to the related method of use, a technician in the field, in order to satisfy further and contingent needs, may make numerous further changes and variations, all also included in the scope of protection of the present invention, such as defined by the attached claims.

Claims

1. Apparatus (1) for compressing and drying air comprising: - a compressor (2); - an air treatment device (3) comprising an adsorption dryer (4), including a hygroscopic material (5); a control unit (25) configured to operate said air treatment device (3) alternatively in two different operating conditions, which include an adsorption operating condition, in which said hygroscopic material (5) absorbs moisture present in the air, and a regeneration operating condition, in which said hygroscopic material (5) releases the absorbed water; wherein said air treatment device (3) is arranged upstream of said compressor (2), with respect to a direction of air flow between an inlet (1a) and an outlet (1b) of said apparatus (1).

2. Apparatus (1) according to claim 1, wherein said apparatus (1) comprises: - at least a first (3a) and at least a second (3b) air treatment device, each comprising a respective adsorption dryer (4a,4b) including a respective hygroscopic material (5a,5b); wherein said control unit (25) alternatively operates said first air treatment device (3a) in said adsorption operating condition, in which said hygroscopic material (5a) absorbs the humidity present in the air, and said second air treatment device (5b) in said regeneration operating condition, in which said hygroscopic material (5b) releases the absorbed water.

3. Apparatus (1) according to any of the preceding claims, wherein said air treatment device (3) comprises: - an air inlet opening (7) and a pre-filter (8) at least at said opening (7), wherein said pre-filter (8) is positioned in an inlet portion (7a) of said air treatment device (3) in which said air inlet opening (7) is defined; - a first chamber (9) communicating with said inlet portion (7a) and in which said hygroscopic material (5) is positioned; said treatment device (3) further comprises a valve (6) at an air outlet opening (10) arranged downstream of said first chamber (9).

4. Apparatus (1) according to the preceding claim, wherein said adsorption dryer (4) comprises at least one air filter (11) configured for the generation of N2 or O2 through which an air flow passes between said inlet opening (7) and said outlet opening (10).

5. Apparatus (1) according to claim 4, wherein said treatment device (3) comprises a second chamber (12), communicating with said first chamber (9) and in which said at least one air filter (11) is positioned.

6. Apparatus (1) according to any of the preceding claims, comprising a cooling circuit (15) of said compressor (2), said air treatment device (3) comprising a heat exchanger (14) configured in such a way as to be traversed by a heat transfer fluid coming from said cooling circuit (15) in such a way as to heat said hygroscopic material (5) when said treatment device (3) operates in said regeneration operating condition.

7. Apparatus (1) according to the preceding claim, wherein said heat exchanger (14) is arranged to contact said first chamber (9) or said first (9) and second (12) chambers.

8. Apparatus (1) according to any of claims 3 to 7, wherein said treatment device (3) comprises a hot fluid container (16) disposed in contact with said first chamber (9) or said first (9) and second (12) chambers, said hot fluid container (16) being adapted to regenerate said hygroscopic material (5) or said hygroscopic material and said at least one air filter (11).

9. Apparatus (1) according to any of claims 3 to 8, wherein said treatment device (3) comprises a suction channel (17) connected to a vacuum pump (18), said vacuum pump (18) being suitable to create vacuum inside said first chamber (9) or inside said first (9) and said second (12) chamber, wherein said control unit (25) operates said vacuum pump (18) in said regeneration operating condition.

10. Apparatus (1) according to claim 1 wherein said absorption dryer (4) comprises a desiccant dehumidifying wheel comprising a hygroscopic material (5), said desiccant dehumidifying wheel including a rotating body in which are defined, alternatively, an adsorption operating portion suitable for adsorbing the humidity present in the air and, a regeneration operating portion in which said hygroscopic material (5) releases the absorbed water.

11. Apparatus (1) according to claim 10, wherein said treatment device (3) comprises said at least one air filter (11) for generating N2 or O2 and wherein said air filter (11) is constructed as a filter wheel comprising, simultaneously, an operating portion adapted to filter the air to generate O2 or N2 and, a regeneration portion wherein the filter (11) is regenerated by the adsorbed particles.

12. Apparatus (1) according to any of the preceding claims, wherein said air treatment device (3) comprises an auxiliary circuit (13) adapted to allow the passage of dry air in said regeneration operating condition, said dry air with flow direction opposite to the moist air entering said regeneration operating phase; preferably said apparatus (1) comprising a single treatment device (3).

13. Method of compressing air by means of an air compression and drying apparatus (1) comprising a compressor (2) and an air treatment device (3), the method comprising: - providing at least one air treatment device (3) arranged upstream of said compressor (2), with respect to a direction of air flow between an inlet (1a) and an outlet of said apparatus (1b), and comprising an absorption dryer (4) including a hygroscopic material (5) and, a heat exchanger (14) through which a heat transfer fluid flows from a cooling circuit (15) of said compressor (2); - drawing in the air with said compressor (2) by making it flow first into the treatment device (3) and then into said compressor (2); - dehumidifying the air, in an adsorption operating condition, in which said hygroscopic material (5) adsorbs the humidity present in the air until the material is saturated;- regenerating said hygroscopic material (5), in a regeneration operating condition in which said hygroscopic material (5) releases the water adsorbed during said adsorption operating condition, by causing said heat transfer fluid to flow, at a regeneration T, into contact with a first chamber containing said hygroscopic material (5) so as to evaporate the water vapour contained in the hygroscopic material and cause it to escape from a discharge opening (20).; 14. Method according to claim 13, wherein said method comprises: - providing an air compression apparatus (3) comprising at least one first (3a) and at least one second (3b) treatment device arranged fluid-dynamically in parallel and each including a respective hygroscopic material (5a, 5b); - dehumidifying the air, in said adsorption operating condition, with said at least one first treatment device (3a); simultaneously - regenerating said hygroscopic material (5b) of said at least one second treatment device (3b), in said regeneration operating condition; - alternating said adsorption operating condition and said regeneration operating condition between said at least one first (3a) and said at least one second (3b) air treatment device.

15. Method according to claim 13, wherein after having dehumidified the air, said method comprises: - switching off said compressor (2) by interrupting the air flow; and after having regenerated said hygroscopic material (5) - reactivating the compressor (2).

16. Method according to claim 13 or 14, wherein said treatment device comprises at least one air filter (11) for generating N2 or O2, the method comprising, during said dehumidifying the air, generating an air passage downstream or upstream of the hygroscopic material (5) in said air filter (11), so as to generate N2 or O2 at the inlet to said compressor (2) and, during said regenerating said hygroscopic material (5), causing a heat transfer fluid to flow, at a regeneration T, into contact with a second chamber (12) containing said air filter (11).