Apparatus for drying compressed air

Description

FIELD OF THE INVENTION

[0001] The present invention concerns an apparatus for drying damp compressed air, completely or mostly eliminating the humidity contained therein. The damp compressed air is introduced inside the apparatus along a defined conveyance path and, after being dried, is expelled at a substantially unchanged pressure.

BACKGROUND OF THE INVENTION

[0002] An apparatus for drying compressed air is known, which eliminates most of the relative humidity, present to about 100%, caused by the reduction in the volume of air during compression.

[0003] The apparatus comprises a box-like containing body, into which damp, warm compressed air is introduced, and from which, after being dried along a defined drying path, it is expelled. Along the path a first heat exchanger and a second heat exchanger, or evaporator, are arranged, the second arranged downstream of the first.

[0004] In the first heat exchanger the compressed air introduced exchanges heat, in a so-called pre-exchange step, with the dried air, before the latter exits from the box-like body. In the second exchanger the air is cooled by exchanging heat with a cooling circuit, in order to lower the temperature and cool the humidity to a condensation point, or dew point. The dried and cooled air is subsequently conveyed along the aforesaid path towards the first exchanger where it is again heated before exiting. Downstream of the second heat exchanger a condensation separator is arranged, which separates and expels the condensed water from the compressed air.

[0005] A first disadvantage of the known apparatus is that the first exchanger and the second exchanger are arranged in a substantially horizontal position inside the box-like containing body and, because of this arrangement, any possible condensation, which forms in the heat exchangers, remains in contact with the surfaces of the exchangers themselves, with the risk of limiting the drying process and causing a possible formation of ice on the walls of the pipes of the exchangers.

[0006] Moreover, in the known apparatus the heat exchangers in the box-like body are arranged so as to determine generally a tortuous drying path, which causes high losses of load of the compressed air.

[0007] A further disadvantage of the known apparatus is that the volumes of the heat exchangers, in most cases, occupy a great deal of space inside the box-like body, such as to prevent both any reduction in the overall size of the apparatus, and any insertion of auxiliary devices, such as for example further condensation separation devices, electronic control devices or suchlike.

[0008] It is also known from US-A-4, 287, 724 a device for cooling air to a temperature below its dew point and for separating condensed liquid from the cooled air to produce dry air. This known device comprises a cylindrical container wherein a pre-cooling section is disposed in the upper portion thereof and a chiller section is disposed in the lower portion thereof. The pre-cooling section comprises four parallel air conduits, each of which lies in a horizontal plane and is formed into a spiral configuration. Interposed with each of the spiralling air conduits are spiralling cooled dry air conduits. Also the chiller section comprises four parallel horizontally oriented, partially cooled air conduits, each of which is formed into a spiral configuration. Therefore, this know device, due to the spiral configuration of the conduits, is very complicated and cumbersome. This document can be seen as the closest prior art and corresponds to the preamble of claim 1.

[0009] One purpose of the present invention is to achieve an apparatus for drying compressed air wherein the arrangement of a first and second heat exchanger allows to reduce to a minimum the losses of load of the compressed air during a drying path.

[0010] Another purpose of the present invention is to achieve an apparatus for drying compressed air by means of which it is possible to obtain a complete separation of the condensed water, and in which the risk of the condensed water remaining on the walls of the respective heat exchangers is minimum.

[0011] A further purpose of the present invention is to achieve an apparatus for drying compressed air having a compact shape and minimum bulk.

[0012] The Applicant has devised, tested and embodied the present invention to achieve these purposes and to obtain other advantages, and to overcome the shortcomings of the state of the art.

SUMMARY OF THE INVENTION

[0013] The present invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics or variants of the main idea of the invention.

[0014] In accordance with the above purposes, an apparatus according to the invention for drying damp compressed air comprises: a box-like containing body having inlet means for the damp compressed air, outlet means for the dried air and conveyor means to convey the compressed air to define a path of the compressed air between the inlet means and the outlet means; first heat exchanger means arranged along the path, in which the damp compressed air introduced is able to exchange heat with the dried air before the latter exits from the box-like body; second heat exchanger means arranged along the path downstream of the first heat exchanger means and associated with cooling means, in order to condense the water contained in the compressed air; collection means to collect the condensed water arriving from the second heat exchanger means. According to the invention, the first heat exchanger means and the second heat exchanger means are arranged in a substantially vertical position along the path.

[0015] This arrangement reduces the space occupied by the heat exchanger means and allows to obtain a compact box-like containing body, at the same time improving the drying and the separation of the humidity. The vertical arrangement encourages the just condensed water to drop due to gravity into the lower zone of the box-like body, without being retained inside the heat exchanger means.

[0016] Moreover, the vertical arrangement of the first and second heat exchanger means allows to limit possible losses of load inside the box-like body and the compressed air is able to both enter and exit from the upper zone of the container. In this way, the path has a simple, substantially U-shaped form, without being tortuous. In a preferential embodiment of the invention, the compressed air is introduced from above descends downwards through the first and second heat exchanger means as far as the lower zone of the box-like body where it is deprived of the condensed water contained therein.

[0017] Subsequently, after the condensation has been separated, the compressed air rises, now dried, towards the outlet means, passing through the first heat exchanger means.

[0018] In a preferential solution, to allow a first separation of the water condensed from the compressed air and to prevent damage due to heat dilations, the first heat exchanger means and the second heat exchanger means are separated from each other by an intermediate compartment, able to insulate them thermally and to ensure a first separation of the condensation.

[0019] Moreover, in one embodiment, in order to optimize the drying, along the path, downstream of the second heat exchanger means, there are separation means to separate the condensed water, so as to make it fall into a relative collection compartment.

[0020] The condensation separation means are advantageously arranged vertically along the path in order to encourage the separation of the condensation, and also to further encourage the condensation to fall due to gravity.

[0021] In one embodiment, the condensation separation means are aligned, directly in sequence, after the second heat exchanger means. According to a variant, the condensation separation means are arranged off-set with respect to the second heat exchanger means.

[0022] According to another variant, the condensation separation means comprise an inclined wall arranged along the path and against which the compressed air is able to impact, to allow the water contained therein to separate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example, with reference to the attached drawings wherein:

• fig. 1 is a sectioned, three-dimensional view of a drying apparatus according to the present invention;
• fig. 2 is a flow chart of the apparatus in fig. 1;
• fig. 3 shows a first variant of the apparatus in fig. 1;
• fig. 4 shows another variant of the apparatus in fig. 1.

DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT OF THE INVENTION

[0024] With reference to figs. 1 and 2, a drying apparatus 10 according to the present invention to dehumidify damp compressed air comprises a hermetically closed container 12. The damp compressed air is able to be introduced into the container 12, through an inlet mouth 14, and to be expelled, after being dried, through an outlet mouth 16.

[0025] In this case, the damp compressed air, with a relative humidity near 100%, is introduced at a pressure of about 7 bar and at a temperature of about 35°C.

[0026] Inside the container 12 a conveyor path P of the compressed air is defined, between the inlet mouth 14 and the outlet mouth 16. The path P is defined along a first vertical channel 20 and a second vertical channel 22, adjacent to the first and separated partly therefrom by means of a wall 21.

[0027] The apparatus 10 comprises a first heat exchanger 24, in which the so-called pre-exchange of air and air takes place, and a second heat exchanger 30, or evaporator, arranged downstream of the first. According to the invention, both the first and the second exchanger 24, 30 are arranged substantially vertically and aligned in the first channel 20.

[0028] This aligned and vertical position of the exchangers allows the compressed air to pass directly, without any deviation in the path, into the second heat exchanger 30, limiting to a minimum the losses of load.

[0029] In the embodiment shown here, both the first heat exchanger 24 and the second heat exchanger 30 are of a known type and comprise a plurality of braze welded aluminum pipes which respectively form air/air circuits or air/cooling fluid circuits. It is clear that the type of heat exchanger is not restrictive for the invention and it is also possible to use any other type of air/air and air/cooling fluid heat exchanger of a known type.

[0030] The first heat exchanger 24 comprises, in this case, first vertical pipes 26 in which the damp warm compressed air passes just after it has been introduced by the mouth 14. The damp warm compressed air exchanges heat with the dried air arriving from the second channel 20 and passing through second pipes 28 (fig. 2).

[0031] The warm compressed air cools slightly, descending to around 20°C and the dried air, which as will be described later arrives cold at around 3°C, is heated before leaving from the outlet mouth 16. To be more exact, the currents of warm and cold air take place completely in counter flow, thus ensuring maximum efficiency of the heat exchange.

[0032] The second heat exchanger 30 is associated with a cooling circuit 32, of a known type, comprising pipes 34 in which a cooling fluid flows, such as for example freon. The second exchanger 30 comprises, in this case, vertical pipes 36 in which the compressed air arriving from the first exchanger 24 passes, and which alternate with the pipes 34 of the cooling circuit 32. In contact with the cooling circuit 32 the compressed air cools to about 3°C and the water contained therein reaches the so-called dew point, and condenses.

[0033] In this case too, the currents of compressed air and of cooling fluid take place in counter flow, thus ensuring maximum efficiency of the heat exchange.

[0034] The dried compressed air at 3°C is conveyed in the second channel 22 towards the first heat exchanger 24, to be reheated to about 30°C.

[0035] The first exchanger 24 and the second exchanger 30 are separated from each other by an intermediate compartment 38, which insulates them thermally to prevent damage caused by dilations of different entities. In the intermediate compartment 38 there is also a first separation of the water condensed from the compressed air arriving from the first exchanger 24.

[0036] The vertical arrangement one above the ether of the heat exchangers 24, 30 also has the advantage that possible condensation water, which forms on the walls, respectively, of the pipes 26, 36 of the first heat exchanger 24 and of the second heat exchanger 30, falls due to gravity into the lower zone of the container 12, where there is a discharge pipe 40. To be more exact, the discharge pipe 40 is connected by means of a nipple 42 to a condensation discharger of a known type, and not shown in the drawings, which is not restrictive for the invention and can be of electronic type, volumetric with a float, timed or otherwise.

[0037] In the embodiment shown here, to facilitate the separation of the water and the compressed air, downstream of the second heat exchanger 30 there is a condensation separator 44, of a known type, such as for example a high efficiency demister. The condensation separator 44 is also arranged aligned vertically with the two heat exchangers 24 and 30, so that the compressed air, passing from the top towards the bottom, further encourages the separation of the condensation, and also guarantees that it falls due to gravity.

[0038] In the lower zone of the container 12, where there is the passage between the first and the second vertical channel 20, 22, along the path P, there is a collection compartment 45 for the fall of the condensation, which prevents the condensation from being possibly transported in the compressed air into the second channel 22.

[0039] Moreover, in the second channel 22, the dried compressed air passes at a relatively reduced speed, thanks to the fact that, in said channel, there are no restrictions in section, so that its cross section is constant. The reduced speed allows to limit the losses of load and prevent the condensation being transported.

[0040] According to a variant, shown in fig. 3, the condensation separator 44 is arranged in the lower zone of the second channel 22, so as to separate the condensed water only after a first separation due to gravity has occurred.

[0041] According to another variant, shown in fig. 4, instead of the condensation separator 44, in the lower zone of the separating wall 21 there is an oblique wall 47, facing towards the first channel 20, and able to encourage the water to separate and fall due to impact therewith.

Claims

1. Apparatus for drying compressed air, comprising: a box-like containing body (12) having inlet means (14) for the compressed air, outlet means (16) for the dried air and conveyor means (20, 22) for said compressed air in order to define a path (P) for said compressed air between said inlet means (14) and said outlet means (16); first heat exchanger means (24) arranged along said path (P) in which the compressed air introduced is able to exchange heat with the dried air before said dried air exits from said box-like body (12); second heat exchanger means (30) arranged along said path (P), downstream of said first heat exchanger means (24), and associated with cooling means (32), to condense the water contained in said compressed air; collection means (40) to collect the condensed water arriving from said second heat exchanger means (30), wherein said first heat exchanger means (24) and said second heat exchanger means (30) are arranged in a substantially vertical position along said path (P), characterized in that said path (P) is substantially U-shaped, and comprises a first vertical segment and a second vertical segment connected together in a lower zone, and in that said first and second heat exchanger means (24, 30) are arranged along said first vertical segment.

2. Apparatus as in claim 1, characterized in that said compressed air is able to enter from above, to descend passing through said first and second heat exchanger means (24, 30), and to rise towards said outlet means (16) passing through said second vertical segment, after giving up said condensed water contained therein, the collection of said condensed water taking place in said lower zone.

3. Apparatus as in claim 1 or 2, characterized in that said first heat exchanger means (24) and said second heat exchanger means (30) are separated from each other by an intermediate compartment (38), able to insulate them thermally and to allow a first separation of said condensed water.

4. Apparatus as in any claim hereinbefore, characterized in that it comprises condensation separation means (44, 47) arranged, along said path (P), downstream of said second heat exchanger means (30).

5. Apparatus as in claim 4, characterized in that said condensation separation means (44) are arranged vertically along said path (P).

6. Apparatus as in claim 4 or 5, characterized in that said condensation separation means (44) are aligned with said first heat exchanger means (24) and with said second heat exchanger means (30).

7. Apparatus as in claim 4, characterized in that said condensation separation means (44) comprise an inclined wall (47) arranged along said path (P) against which said compressed air is able to impact, to allow the separation of the water contained therein.

8. Apparatus as in claim 4, characterized in that said condensation separation means (44) are arranged along said path (P) in an off-set position with respect to said second heat exchanger means (30).

9. Apparatus as in any claim hereinbefore, characterized in that said conveyor means comprise a first channel (20) in which said first heat exchanger means (24) and said second heat exchanger means (30) are arranged, and a second channel (22), through which the dried compressed air is conveyed towards said first heat exchanger means (24), before exiting.

10. Apparatus as in claim 9, characterized in that said second channel (22) is connected at the lower part with said first channel (20), by means of a collection compartment (45) for said condensed water.

11. Apparatus as in claim 9 or 10, characterized in that the transverse section of said second channel (22) is substantially constant in order to prevent variations in the speed of said compressed air after the condensed water has been discharged.

12. Apparatus as in claims 4 and 9, characterized in that said condensation separation means (44) are arranged in said first channel (20).

13. Apparatus as in claims 4 and 9, characterized in that said condensation separation means (44) are arranged in said second channel (22).

Ansprüche

1. Gerät zum Trocknen von Druckluft, umfassend: einen schachtelartigen Behälterkörper (12) mit einer Einlaßeinrichtung (14) für die Druckluft, eine Auslaßeinrichtung (16) für die getrocknete Luft und einer Beförderungseinrichtung (20, 22) für die Druckluft, um einen Pfad (P) für die Druckluft zwischen der Einlaßeinrichtung (14) und der Auslaßeinrichtung (16) zu definieren; eine erste Wärmeaustauscheinrichtung (24), die längs des Pfads (P) angeordnet ist, und in der die eingeführte Druckluft Wärme mit der getrockneten Luft austauschen kann, bevor die getrocknete Luft aus dem schachtelartigen Körper (12) austritt; eine zweite Wärmeaustauscheinrichtung (30), die längs des Pfads (P) stromabwärts von der ersten Wärmeaustauscheinrichtung (24) angeordnet und mit einer Kühlungseinrichtung (32) verbunden ist, um das in der Druckluft enthaltene Wasser zu kondensieren; eine Sammeleinrichtung (40) zum Sammeln des von der zweiten Wärmeaustauscheinrichtung (30) kommenden Kondenswassers, wobei die erste Wärmeaustauscheinrichtung (24) und die zweite Wärmeaustauscheinrichtung (30) in einer im wesentlichen vertikalen Position längs des Pfads (P) angeordnet sind, dadurch gekennzeichnet, daß der Pfad (P) im wesentlichen U-förmig ist und ein erstes vertikales Segment und ein zweites vertikales Segment aufweist, die miteinander in einer unteren Zone verbunden sind, und dadurch, daß die erste und die zweite Wärmeaustauscheinrichtung (24, 30) längs des ersten vertikalen Segments angeordnet sind.

2. Gerät nach Anspruch 1, dadurch gekennzeichnet, daß die Druckluft von oben eintreten kann, um durch die erste und die zweite Wärmeaustauscheinrichtung (24, 30) hindurch abzusteigen und um durch das zweite vertikale Segment hindurch zur Auslaßeinrichtung (16) aufzusteigen, nachdem das darin enthaltene Kondenswasser abgegeben wurde, wobei das Sammeln des Kondenswassers in der unteren Zone stattfindet.

3. Gerät nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die erste Wärmeaustauscheinrichtung (24) und die zweite Wärmeaustauscheinrichtung (30) voneinander durch eine Zwischenkammer (38) getrennt sind, die dazu ausgelegt ist diese thermisch zu isolieren und eine erste Trennung des Kondenswassers zu ermöglichen.

4. Gerät nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß es eine Kondensationstrenneinrichtung (44, 47) aufweist, die längs des Pfads (P) stromabwärts von der zweiten Wärmeaustauscheinrichtung (30) angeordnet ist.

5. Gerät nach Anspruch 4, dadurch gekennzeichnet, daß die Kondensationstrenneinrichtung (44) vertikal längs des Pfads (P) angeordnet ist.

6. Gerät nach Anspruch 4 oder 5, dadurch gekennzeichnet, daß die Kondensationstrenneinrichtung (44) auf die erste Wärmeaustauscheinrichtung (24) und die zweite Wärmeaustauscheinrichtung (30) ausgerichtet ist.

7. Gerät nach Anspruch 4, dadurch gekennzeichnet, daß die Kondensationstrenneinrichtung (44) eine längs des Pfads (P) angeordnete schräge Wand (47) aufweist, gegen die die Druckluft anstoßen kann, um die Trennung des darin enthaltenen Wassers zu ermöglichen.

8. Gerät nach Anspruch 4, dadurch gekennzeichnet, daß die Kondensationstrenneinrichtung (44) längs des Pfads (P) in einer versetzten Position bezüglich der zweiten Wärmeaustauscheinrichtung (30) angeordnet ist.

9. Gerät nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Beförderungseinrichtung einen ersten Kanal (20), in dem die erste Wärmeaustauscheinrichtung (24) und die zweite Wärmeaustauscheinrichtung (30) angeordnet sind, und einen zweiten Kanal (22), durch den die getrocknete Druckluft vor Ihrem Austritt zu der ersten Wärmeaustauscheinrichtung (24) befördert wird, aufweist.

10. Gerät nach Anspruch 9, dadurch gekennzeichnet, daß der zweite Kanal (22) an dem unteren Abschnitt mit dem ersten Kanal (20) durch eine Sammelkammer (45) für das Kondenswasser verbunden ist.

11. Gerät nach Anspruch 9 oder 10, dadurch gekennzeichnet, daß der Querbereich des zweiten Kanals (22) im wesentlichen konstant ist, um Variationen in der Geschwindigkeit der Druckluft nach der Abgabe des Kondenswassers zu verhindern.

12. Gerät nach Anspruch 4 und 9, dadurch gekennzeichnet, daß die Kondensationstrenneinrichtung (44) in dem ersten Kanal (20) angeordnet ist.

13. Gerät nach Anspruch 4 und 9, dadurch gekennzeichnet, daß die Kondensationstrenneinrichtung (44) in dem zweiten Kanal (22) angeordnet ist.

Revendications

1. Dispositif servant à sécher l'air comprimé, comprenant : une enceinte caissonnée (12) comportant des moyens d'entrée (14) de l'air comprimé, des moyens de sortie (16) de l'air séché et des moyens d'amenée (20, 22) dudit air comprimé, afin de définir un parcours (P) dudit air comprimé entre lesdits moyens d'entrée (14) et lesdits moyens de sortie (16) ; un premier système d'échangeur de chaleur (24) disposé le long dudit parcours (P), dans lequel l'air comprimé introduit peut échanger la chaleur avec l'air séché avant que ledit air séché ne sorte dudit corps en caisson (12) ; un second système d'échangeur de chaleur (30) disposé le long dudit parcours (P), en aval dudit premier système d'échangeur de chaleur (24), et associé à des moyens de refroidissement (32) destinés à condenser l'eau contenue dans ledit air comprimé ; des moyens de récupération (40) destinés à récupérer l'eau condensée arrivant dudit second système d'échangeur de chaleur (30), dans lequel ledit premier système d'échangeur de chaleur (24) et ledit second système d'échangeur de chaleur (30) sont disposés en position sensiblement verticale le long dudit parcours (P), caractérisé en ce que ledit parcours (P) est sensiblement en forme de U et comprend un premier segment vertical et un second segment vertical reliés entre eux dans une zone inférieure, et en ce que lesdits premier et second systèmes d'échangeur de chaleur (24, 30) sont disposés le long dudit premier segment vertical.

2. Dispositif selon la revendication 1, caractérisé en ce que ledit air comprimé peut entrer par le dessus, descendre en traversant lesdits premier et second systèmes d'échangeur de chaleur (24, 30), et remonter vers lesdits moyens de sortie (16) en traversant ledit second segment vertical, après s'être déchargé de l'eau condensée qu'il contenait, la récupération de ladite eau condensée s'effectuant dans ladite zone inférieure.

3. Dispositif selon la revendication 1 ou 2, caractérisé en ce que ledit premier système d'échangeur de chaleur (24) et ledit second système d'échangeur de chaleur (30) sont séparés l'un de l'autre par un compartiment intermédiaire (38), apte à les isoler thermiquement et à permettre une première séparation de ladite eau condensée.

4. Dispositif selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comprend des moyens séparateurs de condensation (44, 47) disposés, le long dudit parcours (P), en aval dudit second système d'échangeur de chaleur (30).

5. Dispositif selon la revendication 4, caractérisé en ce que lesdits moyens séparateurs de condensation (44) sont disposés verticalement le long du parcours (P).

6. Dispositif selon la revendication 4 ou 5, caractérisé en ce que lesdits moyens séparateurs de condensation (44) se trouvent dans l'alignement dudit premier système d'échangeur de chaleur (24) et dudit second système d'échangeur de chaleur (30).

7. Dispositif selon la revendication 4, caractérisé en ce que lesdits moyens séparateurs de condensation (44) comprennent une paroi inclinée (47) disposée le long dudit parcours (P) et contre laquelle peut cogner ledit air comprimé pour permettre la séparation de l'eau contenue dans celui-ci.

8. Dispositif selon la revendication 4, caractérisé en ce que lesdits moyens séparateurs de condensation (44) sont disposés le long dudit parcours (P) en position décalée par rapport audit second système d'échangeur de chaleur (30).

9. Dispositif selon l'une quelconque des revendications précédentes, caractérisé en ce que lesdits moyens d'amenée comprennent un premier canal (20) dans lequel sont disposés ledit premier système d'échangeur de chaleur (24) et ledit second système d'échangeur de chaleur (30), et un second canal (22) par lequel l'air comprimé et séché est amené vers ledit premier système d'échangeur de chaleur (24) avant de sortir.

10. Dispositif selon la revendication 9, caractérisé en ce que ledit second canal (22) est relié, au niveau de la partie inférieure, audit premier canal (20) par l'intermédiaire d'un compartiment de récupération (45) de ladite eau condensée.

11. Dispositif selon la revendication 9 ou 10, caractérisé en ce que la section transversale dudit second canal (22) est sensiblement constante afin de prévenir des variations de vitesse dudit air comprimé après l'évacuation de l'eau condensée.

12. Dispositif selon les revendications 4 et 9, caractérisé en ce que lesdits moyens séparateurs de condensation (44) sont disposés dans ledit premier canal (20).

13. Dispositif selon les revendications 4 et 9, caractérisé en ce que lesdits moyens séparateurs de condensation (44) sont disposés dans ledit second canal (22).

Drawing