Apparatus for separating o 2 and n 2 and compressing and drying them and its method of use

Abstract

Apparatus for separating O2 and N2 and compressing them which comprises a compressor and an air-processing device; wherein said air-processing device is provided upstream of said compressor, with respect to an air flow direction, and comprises an absorption generator, which in turn comprises a hygroscopic material suitable for absorbing the humidity present in the air and a filter configured to selectively adsorb gases included in the air entering said apparatus so as to separate O2 and N2, in an adsorption operating condition and, to release the water absorbed by the hygroscopic material and the gases adsorbed by the filter, in a regeneration operating condition.

Description

[0001] Apparatus for separating O2 and N2 and compressing and drying them and its method of use

[0002] The present invention refers to an apparatus for separating O2 and N2 from air, compressing them and drying the air, in particular of the type comprising an absorption generator.

[0003] 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.

[0004] In fact, dry compressed air reduces the risk of damage due to corrosion in the pneumatic system and improves the operation of connected tools and machinery. In this description as well as in the accompanying claims, certain terms and expressions are deemed to have, unless otherwise expressly indicated, the meaning expressed in the following definitions.

[0005] The term "water recovery rate" (or hygroscopy) refers to the measurement as a percentage of the dry weight of the material, that is, as a percentage of water absorbed by a certain amount of dried material. The water recovery rate is expressed as a percentage, indicating the amount of water absorbed by 100 grams of dry material. For example, a recovery rate of 10% means that 100 grams of dried material will absorb 10 grams of water.

[0006] Numerous solutions for drying compressed air are known, such as the one described in Korean patent KR.2509455B1 which describes a dehumidification apparatus with two units working alternately in an operating step and a regeneration step. The solution described in the document provides for an air compressor upstream of the dehumidifier to facilitate the drying of the air by favouring condensation of the water vapour present.

[0007] Korean patent KR.1505879B1 concerns a drying apparatus for laundry dryers and provides for the presence of a compressor upstream of the air dryers to improve the energy efficiency of the process.

[0008] Japanese patent application JP62001434A describes a dehumidification and O2 generation plant. The two processes are carried out with separate devices and in sequence.

[0009] Disadvantageously, some types of plant provide for humid air to be introduced into the compressor which must both compress the air and dehumidify it.

[0010] This results in the need to cool the compressor by providing a dedicated cooling circuit, with the associated energy costs.

[0011] Other types of plant provide for pressure drying, consequently requiring the presence of tanks kept under pressure.

[0012] Also in this case, keeping tanks under pressure and usually cooling the air leaving the compressor results in energy costs that significantly affect the efficiency of a compressed air plant.

[0013] Some plants, which use a compressor, are designed to generate nitrogen and / or oxygen under pressure, for example the oxygen to be placed in cylinders for sanitary use, or the nitrogen used to slow down the deterioration of food packaged in food plants.

[0014] In such cases, additional problems arise in addition to those described above.

[0015] The main disadvantage of this type of plants is related to the need to use filters for the generation of nitrogen or compressed oxygen.

[0016] Another disadvantage concerns the fact of having to compress the entire volume of air entering the compressor and then use only a portion thereof (N2 or O2), with a consequent energy expenditure.

[0017] As part of these needs, the Applicant saw therefore the need to optimize the plants or apparatuses for air compression, reducing the energy costs related to known solutions.

[0018] Further need felt by the Applicant is also linked to the possibility of reducing the overall dimensions and costs related to solutions that require the combination of filters for the generation of nitrogen or compressed oxygen.

[0019] Therefore, the problem underlying the present invention is to provide an apparatus for separating O2 and N2 from the air, compressing them and drying the air which makes it possible to overcome, at least in part, one or more of the drawbacks complained of with reference to the cited prior art.

[0020] An object of the present invention is to provide an apparatus for separating O2 or N2, hereinafter also referred to as separation apparatus, in which it is possible to reduce the energy and overall dimension costs of the apparatus itself.

[0021] It is also an object of the invention to provide a separation apparatus that achieves the above purpose by being easy to build and adaptable to the standard elements of existing plants, so that it can be integrated into the latter by retro-fitting.

[0022] According to a first aspect of the invention, said problem is solved and one or more of said objects are at least in part achieved by an apparatus for separating O2 and N2, compressing them and drying of the air comprising:

[0023] - a compressor;

[0024] - an air-processing device which comprises an adsorption generator comprising a filter configured to separate O2 and N2 from the air and a hygroscopic material; wherein said air-processing device is preferably provided upstream of said compressor, with respect to an air flow direction between an inlet and an outlet of said apparatus. Preferably, said O2 and N2 compression, separation and air drying apparatus comprises a control unit configured in such a way as to actuate said air- processing device alternately in two different operating conditions, including an adsorption operating condition, in which said hygroscopic material absorbs the humidity present in the air and said filter is configured to selectively adsorb gases included in the air entering said apparatus so as to separate O2 and N2, and a regeneration operating condition, in which said hygroscopic material releases the adsorbed water and said filter releases the adsorbed gases.

[0025] The main advantage of the invention is the presence of the air-processing device upstream of the compressor, allowing to introduce already dry air inside the compressor, reducing the wear deriving from humid air, and to optimize the air compression apparatus, reducing the energy costs linked to a refrigeration system of a possible refrigerant dryer and / or a pressure circuit for any adsorption dryers. Another advantage consists in having to compress only the gases of interest, since at the exit of the air- processing device there will be substantially only O2 or N2, so that with the same flow rate entering the apparatus, the compressor must compress smaller volumes with a consequent reduction in compressor wear.

[0026] In addition, lower volumes to be compressed also result in lower energy costs.

[0027] A further advantage of the invention is the use of an adsorption dryer which avoids complicating the apparatus with refrigeration circuits.

[0028] According to some preferred embodiments of the invention said apparatus comprises at least one first and at least one second air-processing device, each comprising a respective absorption generator comprising a filter configured to separate O2 and N2 and a hygroscopic material.

[0029] Preferably, said control unit alternately actuates said first air-processing device in said adsorption operating condition, in which said hygroscopic material absorbs the humidity present in the air and said filter is provided to selectively adsorb gases included in the air entering said apparatus so as to separate O2 and N2, and said second air-processing device in said regeneration operating condition, in which said hygroscopic material releases the absorbed water and said filter releases the adsorbed gases.

[0030] Advantageously, this configuration, with said at least one first and at least one second air-processing device in fluid-dynamic parallel, allows to generate O2 or N2 compressed continuously without ever having to block the apparatus to carry out the regeneration of the hygroscopic material and the filter.

[0031] Preferably, said air-processing device comprises an inlet opening for the air and a prefilter at least in the region of said opening, wherein said prefilter is positioned in an inlet portion of said processing device, wherein said inlet opening for the air is defined.

[0032] The processing device may also comprise a first chamber communicating with said inlet portion and in which said hygroscopic material or said hygroscopic material and said filter are positioned.

[0033] The processing device may also comprise a second chamber communicating with said first chamber and in which said filter is positioned. Said processing device may further comprise a valve at an air outlet opening which is arranged downstream of said first chamber.

[0034] During the regeneration of said hygroscopic material and said filter within said processing device, vapour is released which causes an increase in internal pressure leading to the opening of said valve.

[0035] Preferably, said valve is opened by internal pressures of said processing device at least equal to about 2 atm.

[0036] Advantageously, the described configuration provides for a compact processing device and which includes both the prefilter for a preliminary cleaning of the air, from dust, particulates, etc., and the hygroscopic material capable of dehumidifying the air, as well as the filter, obtaining substantially only dry and clean O2 or N2 in output.

[0037] Therefore, another advantage associated with this feature is the reduction of the overall dimensions and costs due to multiple drying devices and the possible generation of pure gases such as O2 and N2.

[0038] Preferably, said apparatus comprises a cooling circuit of said compressor and said air- processing device comprises a heat exchanger configured to be passed through by a heat-transfer fluid originating from said cooling circuit, thereby heating said hygroscopic material when said processing device operates in said operating condition.

[0039] Advantageously, the heat-transfer fluid used to cool the compressor during its operation, it is also used to heat the processing device in the regeneration operating condition of the hygroscopic material and the filter, paying attention to saving energy in the plant.

[0040] Preferably, said heat exchanger is provided to be in contact with said first chamber or said first and second chamber.

[0041] Furthermore, said processing device may comprise a hot-fluid container arranged in contact with said first chamber or said first and second chamber, said hot-fluid container being apt for regenerating said hygroscopic material or said hygroscopic material and said at least one air filter.

[0042] Advantageously, the presence of said hot-fluid container allows to accelerate the regeneration operating condition when it works in combination with said heat exchanger, or in the absence of said heat exchanger it regenerates said hygroscopic material and / or said filter during the regeneration operating condition using the heat-transfer fluid, which is also used to cool the compressor. According to some preferred embodiments of the invention said processing device comprises a suction channel connected to a vacuum pump, said vacuum pump being apt for creating the vacuum inside said first chamber or inside said first and said second chamber, wherein said control unit actuates said vacuum pump in said regeneration operating condition.

[0043] Combining the vacuum pump with the heat exchanger and / or the hot-fluid container speeds up the regeneration operating condition.

[0044] Preferably, the vacuum pump is provided to realize in said processing device a vacuum comprised between 0.1 atm and 0.7 atm, more preferably 0.3 atm.

[0045] Preferably, said vacuum pump is provided to pump between 1 m3 / h and 10 m3 / h, preferably 5 m3 / h.

[0046] Preferably, said filter comprises a MOF- metal organic framework.

[0047] In particular, said MOF may have a water recovery rate at least equal to 50% m / m and / or require an energy comprised between 2500 kj / Kg and 3000 kj / Kg at 100 C and 1 atm for the release of gases adsorbed thereon.

[0048] According to some embodiments comprising said vacuum pump the MOF require an energy comprised between 2500 kj / Kg and 3000 kj / Kg at 70 C and 0.3 atm for the release of the gases adsorbed thereon.

[0049] According to embodiments wherein said processing device is held at 0.3 atm and 70 C, the vapour partial pressure is about 0.3 atm and the non-condensable gas partial pressure is 0.013 atm. Advantageously, the thermodynamic condition described favours the regeneration of said hygroscopic material and of said filter, reducing regeneration times.

[0050] Advantageously, the emitted vapour can be collected and condensed to produce distilled water.

[0051] According to some preferred embodiments of the invention said absorption generator comprises a generation desiccant wheel comprising a hygroscopic material and a filter, said generation desiccant wheel including a rotating body in which there are alternately defined an adsorption operating portion which is apt for adsorbing the humidity present in the air and for selectively adsorbing gases included in the air entering said apparatus thereby separating O2 and Nz and, a regeneration operating portion in which said hygroscopic material releases the absorbed water and said filter releases the adsorbed gases.

[0052] Advantageously, using said desiccant wheel allows not to interrupt the production of compressed air without having to provide for at least two processing devices, but using only one, with the regeneration operating portion being regenerated while the adsorption operating portion adsorbs the humidity of the air.

[0053] Advantageously, the configuration with the filter for the generation of N2 or O2 included in said generation desiccant wheel allows to use only one processing device and not to interrupt the production of compressed O2 or N2 during the regeneration operating condition.

[0054] Preferably, said air-processing device comprises an auxiliary circuit suitable for allowing the passage of dry air in said regeneration operating condition, said dry air with a flow direction counter to the humid air entering said regeneration operating step.

[0055] Advantageously, the presence of an auxiliary circuit allows not to have to resort to the main plant circuit, being able to size it ad hoc, minimizing energy consumption. In a second aspect thereof, the present invention concerns a method for compressing air by means of an air compression and N2 and O2 separation apparatus comprising a compressor and an air-processing device.

[0056] Preferably, the method envisages providing at least one air- processing device arranged upstream of said compressor, with respect to an air flow direction between an inlet and an outlet of said apparatus and comprising an absorption generator including a hygroscopic material and a filter, a heat exchanger passed through by a heat-transfer fluid originating from a cooling circuit of said compressor.

[0057] Once said air-processing device has been provided, the air can be sucked in with said compressor by making it flow first into the processing device and then into said compressor. In this way the air is dehumidified and O2 and N2 are separated, in an adsorption operating condition, in which said hygroscopic material adsorbs the humidity present in the air up to saturation of the material itself and said filter selectively adsorbs gases included in the air entering said apparatus, said adsorbed gases not being O2 or N2.

[0058] The method further provides for regenerating said hygroscopic material and said filter, in a regeneration operating condition in which said hygroscopic material releases the water adsorbed during said adsorption operating condition and said filter releases the gases adsorbed during said adsorption operating condition, making said heat-transfer fluid flow at a regeneration temperature T and said heattransfer fluid being in contact with a first chamber containing said hygroscopic material, so as to evaporate the water vapour contained in the hygroscopic material and to make it outflow from a discharge opening. Regeneration temperature T means a temperature that facilitates the regeneration operating condition, favouring and / or speeding up the evaporation of the water contained in the hygroscopic material and / or gases retained in the air filter.

[0059] The main advantage of the method according to the present aspect is the use of the heat-transfer fluid for the regeneration of the hygroscopic material and the filter, wherein said heat-transfer fluid absorbs heat in the cooling step of the compressor and releases it in the regeneration operating condition of the hygroscopic material and the filter, thus resulting in energy savings.

[0060] Another advantage of the invention lies in the simplicity of implementation, and in the possibility of integrating said apparatus into a pre-existing air compression plant by refitting the plant.

[0061] Preferably, said method envisages providing an air compression apparatus comprising at least one first and at least one second processing device which are placed fluid-dynamically in parallel and each including a respective hygroscopic material.

[0062] Furthermore, the method provides for dehumidifying the air, in said adsorption operating condition, with said at least one first processing device and simultaneously regenerating said hygroscopic material of said at least one second processing device, in said regeneration operating condition.

[0063] Finally, the method provides for alternating said adsorption operating condition and said regeneration operating condition between said at least one first and said at least one second air-processing device.

[0064] Advantageously, this method allows to produce compressed air continuously without having to interrupt the production process, optimizing the production of compressed air in terms of time. When a single processing device is used, after dehumidifying the air, the method preferably provides for switching off said compressor interrupting the air flow; and after said hygroscopic material has been regenerated, it provides for reactivating the compressor.

[0065] According to some preferred embodiments, wherein said processing device comprises at least one filter, the method comprises, during dehumidification of the air, generating an air passage downstream or upstream of the hygroscopic material in said filter, in such a way as to separate N2 and O2 thereby creating a flow substantially only of N2 or O2 in input to said compressor and, during regeneration of the hygroscopic material, making a heat-transfer fluid flow, at a regeneration T, in contact with a second chamber containing said filter.

[0066] In this way the method allows to dehumidify the air and generate O2 or N2 in the same adsorption condition and to regenerate the hygroscopic material and the filter in the same regeneration condition, optimizing the regeneration and absorption times. Note that the preferred aspects illustrated above in relation to one aspect may find similar application in further aspects of the invention as well. These characteristics and the advantages associated with them will be even better apparent from the detailed description of some preferred embodiments of the invention which will be illustrated, by way of non-limiting example, with reference to the accompanying drawings in which: figure 1 is a schematic representation of an apparatus for separating O2 and N2 according to the invention; figure 2 is another schematic representation of an apparatus for separating O2 and N2 according to the invention in a second embodiment; figure 3 is a further schematic representation of an apparatus for separating O2 and N2 according to the invention in a further embodiment; figure 4 is a perspective view of an air-processing device comprised in said apparatus according to the invention; figure 5 is a perspective view of a preferred embodiment of the device of figure 4; and figure 6 is a schematic representation of a preferred embodiment of said apparatus.

[0067] With reference to the figures, a preferred embodiment of an apparatus for separating O2 and N2 and compressing them is represented globally indicated with reference numeral 1.

[0068] The apparatus 1 for separating O2 and N2 comprises a compressor 2 and an airprocessing device 3.

[0069] Said air-processing device 3 is provided upstream of said compressor 2, with respect to an air flow direction between an inlet la and an outlet lb of said apparatus 1, and it comprises an absorption generator 4, which in turn comprises a hygroscopic material 5 and a filter 11.

[0070] The apparatus 1 also comprises a control unit 25, illustrated for example in figure 4, configured in such a way as to actuate the air- processing device 3 alternately in two different operating conditions including: an adsorption operating condition, in which said hygroscopic material 5 absorbs the humidity present in the air and said filter 11 is configured to selectively adsorb gases comprised in the air entering said apparatus 1 thereby separating O2 and N2, and a regeneration operating condition, in which said hygroscopic material 5 releases the absorbed water and the filter 11 releases the adsorbed gases.

[0071] The main advantage of the present invention lies in arranging the air-processing device 3 upstream of the compressor 2, introducing dry O2 or N2 into the compressor 2 itself, reducing its wear due to humid air, without the need to resort to a refrigerant plant, with consequent economic savings in terms of energy.

[0072] As shown in figures 4, 5 and 6, the air-processing device 3 may comprise an inlet opening 7 for the air and a prefilter 8 at least in the region of said opening 7. Advantageously, the prefilter 8 is positioned in an inlet portion 7a of said processing device 3 and is suitable for the removal of unwanted particles and / or oil particles.

[0073] According to some embodiments, such as those shown in the figures, the inlet opening 7 comprises a closing element 24 comprising a plurality of holes.

[0074] Preferably, to control the opening and closing of the inlet opening 7, the processing device 3 comprises an inlet valve 26 and a respective pneumatic actuator 27 controlled by said control unit 25.

[0075] According to some embodiments of the invention the apparatus 1 comprises at least one first 3a and at least one second 3b air- processing device, each comprising a respective absorption generator 4a, 4b including a respective hygroscopic material 5a, 5b and a respective filter 11a, lib.

[0076] It will be appreciated that the control unit 25 alternately actuates the first airprocessing device 3a in said adsorption operating condition, in which the hygroscopic material 5a absorbs the humidity present in the air and the filter 11a is provided to selectively adsorb gases included in the air entering said apparatus 1 thereby separating O2 and N2, and actuates the second air-processing device 3b in said regeneration operating condition, in which the hygroscopic material 5b releases the absorbed water and the filter lib releases the adsorbed gases. Advantageously, this configuration with two devices 3a, 3b in parallel allows to produce O2 or N2 continuously without ever having to block the plant 1 to carry out the regeneration of the hygroscopic material 5a, 5b.

[0077] Preferably, the two devices are arranged in fluid-dynamic parallel along the line of the plant 1 and the flows are controlled by a group of suitably actuated valves 6a, 6b.

[0078] In the embodiment example of figures 5 and 6, the valve assembly 6a, 6b comprises a three-way valve 6.

[0079] According to embodiments that provide a first air-processing device 3a and a second air-processing device 3b, each device comprises respectively a first inlet valve 26a and a second inlet valve 26b that alternately operate in opening and closing, allowing to perform the absorption operating condition in the first airprocessing device 3a and, simultaneously, to perform the regeneration operating condition in the second air-processing device 3b, or vice versa.

[0080] The air-processing device 3 may further comprise a first chamber 9 communicating with said inlet portion 7a and in which the hygroscopic material 5 is positioned, in said adsorption operating condition and to release it, in said regeneration operating condition.

[0081] Preferably, the prefilter 8 has a toroidal shape that develops around the first chamber 9 making a compact device 3.

[0082] The processing device 3 may further comprise a valve 6 at an air outlet opening 10.

[0083] According to preferred embodiments of the invention the processing device comprises at least one filter 11 for the separation of N2 and O2.

[0084] Therefore, an advantage of the present invention is to provide a single device 3 that includes both the function of dryer and O2 or N2 generator, thereby reducing the overall dimensions in a plant line 1 and the services of the different devices 3, with a consequent economic saving in terms of space and energy.

[0085] To be able to arrange the air filter 11 for the generation of O2 or N2, the processing device preferably comprises a second chamber 12, communicating with said first chamber 9 and wherein the at least one filter 11 is positioned.

[0086] Preferably, the first chamber 9 and the second chamber 12 are separated by a perforated septum 21, insertable between the first 9 and the second chamber 12 once the hygroscopic material 5 or the filter 11 is inserted.

[0087] Alternatively, the first chamber 9 is concentric to the second chamber 12 and the second chamber 2 is wrapped by the first chamber 9 so that the incoming air flow is first dehumidified and then filtered generating Gh or N2.

[0088] Preferably, the air-processing device 3 comprises an auxiliary circuit 13 suitable for allowing the passage of dry air in the regeneration operating condition, said dry air with a flow direction counter to the humid air entering the adsorption operating condition. To allow said auxiliary circuit 13 to operate, said air compression apparatus 1 may comprise a fan 14 that feeds the dry air into the device 3.

[0089] For example, in the embodiment of the invention in figure 2, while said first processing device 3a is in the adsorption operating condition, a first valve 6a is opened, allowing an air flow between the first processing device 3a and the compressor 2 and a second valve 6b is closed, preventing an air flow between the second processing device 3b and the compressor 2. Furthermore, a valve C comprised in said auxiliary circuit 13 is closed, preventing the outflow of the water released from said hygroscopic material 5 in the form of water vapour, while a valve D is opened, allowing the flow of a part of the dry air, produced in the first device 3a, in the second device 3b, favouring the regeneration operating condition. Alternatively (figure 3), part of the dry and compressed O2 or N2 is directed towards said processing device 3 in a portion of the plant 1 that can be isolated fluid- dynamical ly and, when in the regeneration operating condition, a valve E is opened which allows the expansion of the compressed gas in said processing device 3. Furthermore, with a view to saving energy in the apparatus 1, the processing device 3 may comprise a heat exchanger 14 which is passed through by a heattransfer fluid originating from a cooling circuit 15, preferably, of said compressor 2, with the function of regenerating the hygroscopic material 5. The heat exchanger 14 can be arranged in contact with said first chamber 9 or with said first 9 and second 12 chamber, when the latter is present. Preferably, said heattransfer fluid is oil, alternatively it is hot air.

[0090] In this way, the heat-transfer fluid used to cool the compressor 2 during its operation, it is also used to heat the processing device 3 in the regeneration operating condition of the hygroscopic material 5 and the filter 11, paying attention to the energy saving in the plant 1.

[0091] Preferably, the processing device 3 comprises a temperature sensor 22, provided to monitor the temperature of the heat-transfer fluid introduced into the processing device 3. Furthermore, the processing device 3 could comprise a hot- fluid container 16, also known as a heating unit, arranged in contact with said first 9 chamber or said first 9 and second 12 chamber. The hot-fluid container 16 is suitable for regenerating the hygroscopic material 5 or the hygroscopic material 5 together with the air filter 11.

[0092] The possible combined action of the temperature increase due to the presence of the heat exchanger 14 and / or the hot-fluid container 16 and of the dry air introduced into the processing device 3, allow to regenerate the hygroscopic material 5 and the filter 11 for the generation of O2 or N2.

[0093] A further embodiment of the invention provides that the processing device 3 comprises a suction channel 17 connectable to a vacuum pump 18 comprised in said apparatus 1. The vacuum pump 18 is advantageously suitable for creating the 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 of the filter 11. As shown in figures 4, 5 and 6, the air-processing device may comprise an actuator, not illustrated in the figure, which acts on the valve 6 at the outlet opening 10 for the air. The actuator opens the valve 6 during the absorption operating condition allowing the flow of the air sucked in by the compressor 2. During the regeneration operating condition, the actuator is deactivated and the valve 6 is closed, however leaving the inlet opening 7 open to allow the evaporation of the water adsorbed on the hygroscopic material 5 and the desorption of the particles adsorbed on the filter 11 for the separation of O2 and N2, transported by the convective motion of the dry air introduced through the auxiliary circuit 14.

[0094] According to some embodiments not shown in the figure, the absorption generator 4 comprises a generation desiccant wheel including, at the same time, an adsorption operating portion suitable for absorbing the humidity present in the air and for selectively adsorbing gases contained in the air, a regeneration operating portion in which the water absorbed thereon is evaporated and the gases are released.

[0095] Advantageously, this configuration of the invention allows to avoid the configuration with two devices 3 in fluid-dynamic parallel and in any case ensures the continuity of the plant 1, simultaneously carrying out the adsorption and regeneration operating conditions.

[0096] Furthermore, said processing device 3 may comprise at least one filter 11 for the separation of N2 and O2, wherein said filter 11 is comprised in said generating desiccant wheel comprising, at the same time, an adsorption operating portion suitable for separating O2 and N2 and, a regeneration operating portion wherein the filter 11 is regenerated by the absorbed particles.

[0097] Advantageously, the fact that the generation desiccant wheel comprises both the hygroscopic material 5 and the filter 11 allows to use a single drying and O2 or N2 generation device 3 upstream of a compressor 2 along the line of the apparatus 1 for the generation of the compressed air.

[0098] It will be appreciated that the present invention further concerns a method of operation of an air compression apparatus 1 comprising a compressor 2 and an air- processing device 3.

[0099] The method envisages providing at least one air-processing device 3 arranged upstream of the compressor 2, with respect to an air flow direction between an inlet and an outlet of said apparatus 1. The method also provides for using an absorption generator 4, which in turn comprises a hygroscopic material 5, a filter 11 and a heat exchanger 14 passed through by a heat-transfer fluid originating from a cooling circuit 15 of the compressor 2.

[0100] Once the air-processing device 3 has been provided, it is possible to suck in the air with said compressor 2 making it flow first into the processing device 3 and then into the compressor 2 to dehumidify the air and separate O2 and N2, in an absorption operating step, through said hygroscopic material 5 and the filter 11 up to saturation of the material and the filter themselves.

[0101] Preferably, to identify the saturation of the hygroscopic material 5, the processing device 3 comprises one or more humidity sensors connected with the control unit 25 which detects the humidity value measured by the sensors and, when this value exceeds a predetermined threshold, said control unit 25 interrupts the adsorption operating condition of the device.

[0102] Preferably, to identify the saturation of the filter 11, the processing device 3 comprises one or more O2 or N2 sensors connected with the control unit 25 which detects the partial pressure of said gases measured by the sensors and, when this value exceeds a predetermined threshold, said control unit 25 interrupts the adsorption operating condition of the device.

[0103] In fact, the method provides for regenerating the hygroscopic material 5 and the filter 11, in a regeneration operating condition, by making the heat-transfer fluid flow at a regeneration temperature T around the first chamber 9 containing the hygroscopic material 5 and around the second chamber 12 containing the filter 11, thereby evaporating the water vapor contained in the hygroscopic material 5 and desorb the gases from the filter 11, so that they outflow from the discharge opening 20.

[0104] According to embodiments comprising the vacuum pump 18, the discharge opening 20 is at the vacuum pump 18, as visible in figure 5. Alternatively, the discharge opening 20 could coincide with the inlet valve 26, which in the regeneration operating condition allows the outflow of the water vapour.

[0105] Preferably, said regeneration temperature is comprised between 60°C and 100°C, more preferably comprised between 65°C and 90°C, preferably it is 70°C.

[0106] If the apparatus comprises only one processing device 3, the method may provide for switching off the compressor 2 interrupting the air flow and, after the hygroscopic material 5 has been regenerated, reactivating the compressor 2. According to embodiments in which the air compression apparatus 1 comprises at least one first 3a and at least one second 3b processing device being placed fluid- dynamically in parallel and each including a respective hygroscopic material 5a, 5b, once provided, the method provides for dehumidifying the air, in the adsorption operating condition, with the first processing device and, simultaneously regenerating the hygroscopic material 5b to the filter lib of the second processing device 3b, in said regeneration operating condition.

[0107] The method also provides for alternating said adsorption operating condition and said regeneration operating condition between said first 3a and second 3b airprocessing device.

[0108] Advantageously, this embodiment allows a continuous production of dry and compressed O2 or N2.

[0109] Since the processing device 3 comprises at least one generation filter 11 for the generation of N2 or O2, the method comprises, during the absorption operating condition, a passage of the air downstream or upstream of the hygroscopic material 5 in said filter 11, thereby generating N2 or O2 in input to the compressor 2.

[0110] Furthermore, in the regeneration operating condition, the method may provide for making the heat-transfer fluid, at the regeneration T, flow in contact with the second chamber 12 containing the air filter 11, thereby regenerating it before a new absorption operating condition.

[0111] Preferably, to identify the saturation of the generation filter 11, the air-processing device 3 comprises N2 or O2 concentration sensors connected to the control unit 25 suitable for regulating the operating and regeneration step of the air filter 11 as well. To satisfy further and contingent needs, a person skilled in the art may make numerous further modifications and variations to the compressed air generation apparatus and related method of use described above, all of which are included in the scope of protection of the present invention, as defined by the attached claims.

Claims

Claims1. An apparatus (1) for separating O2 and N2 and compressing them comprising:- a compressor (2);- an air-processing device (3) which comprises an adsorption generator (4) comprising a filter (11) configured to separate O2 and N2 and a hygroscopic material (5);- a control unit (25) configured so as to actuate said air-processing device (3) alternately in two different operating conditions including: an adsorption operating condition, in which said hygroscopic material (5) absorbs the humidity present in the air and said filter (11) is configured to selectively adsorb gases included in the air entering said apparatus (1) thereby separating O2 and N2, and a regeneration operating condition, wherein said hygroscopic material (5) releases the adsorbed water and said filter (11) releases the adsorbed gases; wherein said air-processing device (3) is provided upstream of said compressor (2), with respect to an air flow direction between an inlet (la) and an outlet (lb) of said apparatus (1).

2. The apparatus (1) according to claim 1, wherein said apparatus (1) comprises:- at least one first (3a) and at least one second (3b) air-processing device, each comprising a respective filter (11a, lib) and a respective absorption generator (4a, 4b) including a respective hygroscopic material (5a, 5b); wherein said control unit (25) alternately actuates said first air- processing device (3a) in said adsorption operating condition, wherein said hygroscopicmaterial (5a) absorbs the humidity present in the air and said filter (11a) is provided to selectively adsorb gases comprised in the air entering said apparatus (1) thereby separating O2 and N2, and said second air-processing device (5b) in said regeneration operating condition, in which said hygroscopic material (5b) releases the adsorbed water and said filter (11) releases the adsorbed gases.

3. The apparatus (1) according to any one of the preceding claims, wherein said air-processing device (3) comprises:- an inlet opening (7) for the air and a prefilter (8) at least in the region of said opening (7), wherein said prefilter (8) is positioned in an inlet portion (7a) of said air-processing device (3) in which said inlet opening (7) for the air is defined;- a first chamber (9) communicating with said inlet portion (7a) and wherein said hygroscopic material (5) is positioned;- a second chamber (12), communicating with said first chamber (9) and wherein said at least one filter (11) is positioned; said processing device (3) further comprises a valve (6) at an air outlet opening (10) which is arranged downstream of said first chamber (9).

4. The apparatus (1) according to any one of the preceding claims, wherein said filter (11) is passed through by an air flow between said inlet opening (7) and said outlet opening (10), wherein said outlet air flow comprises at least 90% v / v of N2.

5. The apparatus (1) according to any one of claims 1 to 3, wherein said filter (11) is passed through by an air flow between said inlet opening (7) and said outlet opening (10), wherein said outlet air flow comprises at least 90%v / v Of O2.

6. The apparatus (1) according to any one of the preceding claims, comprising a cooling circuit (15) of said compressor (2), said air-processing device (3) comprising a heat exchanger (14) configured so as to be passed through by a heat-transfer fluid originating from said cooling circuit (15) thereby heating said hygroscopic material (5) and said filter (11) when said processing device (3) operates in said regeneration operating condition.

7. The apparatus (1) according to the preceding claim, wherein said heat exchanger (14) is provided in contact with said first chamber (9) or said first (9) and second (12) chamber.

8. The apparatus (1) according to any one of claims 3 to 7, wherein said processing device (3) comprises a hot-fluid container (16) arranged in contact with said first chamber (9) or said first (9) and second (12) chamber, said hot-fluid container (16) being suitable for regenerating said hygroscopic material (5) and said filter (11).

9. The apparatus (1) according to any one of claims 3 to 8, wherein said processing device (3) comprises a suction channel (17) connected to a vacuum pump (18), said vacuum pump (18) being suitable for creating the vacuum inside said first chamber (9) or inside said first (9) and said second (12) chamber, wherein said control unit (25) actuates said vacuum pump (18) in said regeneration operating condition.

10. The apparatus (1) according to claim 1 wherein said adsorption generator (4) comprises a generation desiccant wheel comprising a hygroscopic material (5) and a filter (11), said generation desiccant wheel including a rotating body in which there are alternately defined an adsorption operatingportion apt to absorb the humidity present in the air and for selectively adsorbing gases comprised in the air entering said apparatus (1) thereby separating O2 and N2 and, a regeneration operating portion wherein said hygroscopic material (5) releases the absorbed water and said filter (11) releases the adsorbed gases.

11. The apparatus (1) according to any one of the preceding claims, wherein said air-processing device (3) comprises an auxiliary circuit (13) suitable for allowing the passage of dry air in said regeneration operating condition, said dry air with a flow direction counter to the humid air entering said regeneration operating step; said apparatus (1) preferably comprising a single processing device (3).

12. The apparatus (1) according to any one of the preceding claims, wherein said filter (11) comprises a metal organic network (MOF).

13. The apparatus (1) according to claim 12 wherein said MOF has a water recovery rate at least equal to 50% m / m.

14. The apparatus (1) according to claim 12 or 13, wherein said MOF requires an energy comprised between 2500 kj / Kg and 3000 kj / Kg at 100°C for releasing the gases adsorbed thereon.

15. A method for compressing air by an air compression and N2 and O2 separation apparatus (1) comprising a compressor (2) and an air-processing device (3), the method comprising:-providing at least one air-processing device (3) arranged upstream of said compressor (2), with respect to an air flow direction between an inlet (la) and an outlet of said apparatus (lb), and comprising an absorption generator (4) including a hygroscopic material (5) and a filter (11), a heatexchanger (14) passed through by a heat-transfer fluid which originates from a cooling circuit (15) of said compressor (2);-sucking in the air with said compressor (2) making it flow first into the airprocessing 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 up to saturation of the material itself;-separating O2 or Nz from the air, in said adsorption operating condition, in which said filter (11) selectively adsorbs gases comprised in the air entering said apparatus (1), said adsorbed gases not being O2 or N2;-regenerating said hygroscopic material (5) and said filter (11), in a regeneration operating condition in which said hygroscopic material (5) releases the water adsorbed during said adsorption operating condition and said filter (11) releases the gases adsorbed during said adsorption operating condition, making said heat-transfer fluid flow, at a regeneration T, in contact with a first chamber containing said hygroscopic material (5) and in contact with a second chamber containing said filter (11), so as to evaporate the water vapour contained in the hygroscopic material and to release the gases adsorbed on said filter (11) and to make them outflow from a discharge opening (20).

16. The method according to claim 15, wherein said method comprises:- providing an air compression apparatus (3) comprising at least one first (3a) and at least one second (3b) processing device which are placed fluid- dynamically in parallel and each including a respective hygroscopic material (5a, 5b) and a respective filter (11a, lib);-dehumidifying the air, in said adsorption operating condition, with said at least one first air-processing device (3a);-separating O2 or N2 from the air, in said adsorption operating condition, with said at least one first air-processing device (3a); simultaneously-regenerating said hygroscopic material (5b) and said filter (lib) of said at least one second processing 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-processing device.

17. The method according to claim 15, wherein after dehumidifying the air, said method comprises:-switching off said compressor (2) interrupting the air flow; and after regenerating said hygroscopic material (5) and said filter (11);- reactivating the compressor (2).

18. The method according to claim 15 or 16, wherein said filter (11) is passed through by an air flow, wherein said outlet air flow comprises at least 90% v / v of O2.

19. The method according to claim 15 or 16, wherein said filter (11) is passed through by an air flow, wherein said outlet air flow comprises at least 90% v / v of N2.

20. The method according to claim 15 or 16 wherein in said regeneration operating condition it comprises- sucking in with a vacuum pump (18) connected to said first chamber (9)or to said first (9) and second chamber (12), said vacuum pump (18) being suitable for creating the vacuum inside said first chamber (9) or inside said first (9) and said second (12) chamber.

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