EP3116624A1

EP3116624A1 - Oil separator for cooling and/or air conditioning plants

Info

Publication number: EP3116624A1
Application number: EP15718597.6A
Authority: EP
Inventors: Mauro Avanzini
Original assignee: Dena Line SpA
Current assignee: Dena Line SpA
Priority date: 2014-03-14
Filing date: 2015-03-16
Publication date: 2017-01-18
Also published as: WO2015136507A1

Abstract

Oil separator for cooling and/or air conditioning plants including an external shell (26), an inlet channel (1 1, 1 1 1) for the gaseous stream to be treated, connected to said external shell (26), a filtering element (12) disposed in the transit path of the gaseous stream, an outlet for the purified gaseous stream (24) made in the external shell (26), and a collection zone (21) for the oil or other particles separated from said gaseous stream. The oil separator (10) comprising a passage pipe connected to the inlet channel (1 1) of the gaseous stream and to the filtering element (12), and a diversion pipe (13), disposed around the passage pipe, and defining an outlet zone (18) of the gaseous stream, disposed below the gaseous stream outlet (24) provided in the external shell (26).

Description

OIL SEPARATOR FOR COOLING AND/OR AIR

CONDITIONING PLANTS

FIELD OF THE INVENTION

The present invention concerns an oil separator for cooling and/or air conditioning plants, suitable for the elimination of droplets of oil from a stream of fluid.

In particular, the separator can be applied, for example but not only, to remove oil from a cooling fluid such as Freon for example, used as a heat-carrying fluid in a cooling cycle to refresh and/or condition the air inside a room.

BACKGROUND OF THE INVENTION

Plants and cooling circuits are known, used to refresh the air in closed or partly closed rooms or spaces.

Such plants provide to use a heat-carrying fluid, generally a halogenated fluid such as Freon for example which, traveling along a cooling circuit, undergoes one or more changes of state, by means of which it is possible, for example, to remove heat from an internal space and give it up to the outside, guaranteeing the desired cooling and/conditioning.

The thermodynamic cycle that is established in said circuit normally comprises at least a compression step, performed mechanically by a compressor, by means of which the heat-carrying fluid is brought to optimal conditions to pass from an aeriform phase, determined by the absorption of heat from the room to be cooled and/or conditioned, to a liquid phase, with consequent emission of a stream of latent heat into the external space.

One disadvantage encountered in these circuits is that the oil can be drawn, by the heat-carrying fluid, into the different units that form the cooling circuit and located downstream of the compressor: these droplets are able to alter the overall performance of the whole cooling plant.

To overcome this disadvantage, units to separate the oil from the cooling fluid have been made, which can generally be classified into two main categories, that is, cyclonic systems and systems with coalescent filters.

Cyclonic systems are characterized by a geometric conformation, in general cylindrical, able to receive, for example with a tangential entrance, a mixed stream of oil and cooling fluid in the gaseous state: this geometric conformation allows to impart a spiral or vortex motion to the entering stream.

In this way, the centrifugal force that is created, and the greater inertia, or the weight, of the oil with respect to the cooling fluid, allow to obtain the desired separation. In particular, the droplets of oil, impacting against the walls of the unit, are separated from the gaseous stream of cooling fluid and subsequently fall into the lower part of the unit where they are collected in an appropriate zone, while the gaseous stream exits substantially without any of the oil content that was present at entry.

One disadvantage of this known solution is the high costs of the cyclonic system, which reduces its possible applications.

Systems with coalescent filters, instead, are based on the principle of filtration of the entering stream, which filtration is performed by imposing a passage of the gas and the oil, normally, from the bottom to the top with a predetermined passage speed, in general equal to about 0.5 m/s.

In this way, it is possible to promote a coalescence process of the droplets of oil which, tending to agglomerate, can be retained with greater ease by the filter and therefore separated from the gaseous stream.

One disadvantage of this known solution concerns the low efficiency of removal of the droplets of oil from the cooling fluid obtained overall by coalescence filters, since the times required for an optimal purification are excessively high.

Documents FR 788.702, US 1.463.990 and US 3.453.198 describe separators to separate oil from a stream of compressed air.

One purpose of the present invention is to make an oil separator for cooling and/or air conditioning plants that can remove a large quantity of oil from the cooling fluid.

Another purpose of the present invention is to make an oil separator for cooling and/or air conditioning plants that has low costs, both in production and management.

Another purpose of the present invention is to make an oil separator for cooling and air-conditioning plants that can remove a large quantity of oil, at the same time guaranteeing that the gaseous stream remains inside the separator for a limited time.

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

SUMMARY OF THE INVENTION

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

In accordance with the above purposes, the present invention concerns a separator of oil, and/or of other liquid or solid impurities, for cooling and/or air conditioning plants, able to remove from a gaseous stream, such as for example a cooling fluid, droplets of oil and/or said other impurities transported in the gaseous stream.

In accordance with possible forms of embodiment, the separator according to the invention comprises a substantially cylindrical external shell, an inlet channel for the gaseous stream to be treated, connected to the external shell, a filtering element disposed in the transit path of the gaseous stream, an outlet for the purified gaseous stream made in the external shell, and a collection zone for the oil or other particles separated from the gaseous stream.

According to a characteristic of the present invention, the separator comprises a passage pipe connected to the inlet channel of the gaseous stream and comprising the filtering element, and a diversion pipe, disposed around the passage pipe, and defining an outlet zone of the gaseous stream, disposed below the gaseous stream outlet provided on the external shell.

In some forms of embodiment, the diversion pipe is disposed coaxially with respect to the passage pipe, and has a greater length and diameter than the passage pipe.

With this configuration, the gaseous stream fed to the separator, normally by the compressor, enters into the external shell passing through the passage pipe and therefore through the filtering element associated with the passage pipe. Then, it exits into the diversion pipe that, thanks to its larger diameter, determines a slowing down of the gaseous stream which then exits into the volume of the external shell through the outlet zone.

Since the outlet zone of the diversion pipe is below the exit of the gaseous stream provided on the external shell, the gaseous stream is forced to travel upward, after possibly repeatedly hitting against internal walls of the external shell.

In this way, thanks to the double effect of the reduction in speed in its passage in the diversion pipe, and to the force of gravity that acts on the stream forced upward, the separator obtains a better effect of separation and fall of the droplets of oil and other impurities, which are separated from the gaseous stream. In particular, inside the separator a progressive reduction of the speed of the gaseous stream is determined, in order to leave the droplets of oil enough time to separate from the gas.

In some forms of embodiment, the separator can provide, below the diversion pipe, a holed dividing plate, in order to complete the separation of the oil from the gaseous stream.

In accordance with possible forms of embodiment, the outlet zone of the diversion pipe can be asymmetric with respect to a vertical axis of the passage pipe, and is obtained by means of an intersection between the passage pipe and a plane inclined by an acute angle with respect to its vertical axis.

In accordance with possible forms of embodiment, in its lower part and below the holed dividing plate, the separator comprises the collection zone, from which the droplets of oil can be removed by means of a removal mean, connected to the oil outlet.

In accordance with possible forms of embodiment, the diversion pipe and the filtering element are made in a single piece, substantially constituting a single element.

In accordance with possible forms of embodiment, the filtering element can be of the replaceable type, for example if it is blocked after a certain length of time and use, or even on the basis of the specific type of application.

In accordance with possible forms of embodiment, the filtering element can be connected to the inlet channel by means of a filter holder, the inlet channel extending as far as inside the passage pipe, so as to oblige the gaseous stream to pass through the filtering element and, only afterward, to exit from the passage pipe.

In accordance with possible forms of embodiment, the separator can also comprise a safety valve, connected in its upper part or in a lateral portion of the external shell, to enable the gaseous stream to exit in an emergency and/or in the event of a malfunction of the separator.

BRIEF DESCRIPTION OF THE DRAWINGS

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

- fig. 1 is a section view of an oil separator for cooling and/or air conditioning plants in accordance with the present invention;

- fig. 2 is an enlarged schematic representation of part of an oil separator for cooling and/or air conditioning plants of fig. 1 in accordance with the present invention;

- fig. 3 is a section view of an oil separator for cooling and/or air conditioning plants according to a variant of fig. 1.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DETAILED DESCRIPTION OF SOME FORMS OF EMBODIMENT

We shall now refer in detail to the various forms of embodiment of the present invention, of which one or more examples are shown in the attached drawing. Each example is supplied by way of illustration of the invention and shall not be understood as a limitation thereof. For example, the characteristics shown or described insomuch as they are part of one form of embodiment can be adopted on, or in association with, other forms of embodiment to produce another form of embodiment. It is understood that the present invention shall include all such modifications and variants.

In accordance with the present invention, forms of embodiment of the invention described here concern an oil separator 10 for cooling and/or air conditioning plants, able to treat a gaseous stream such as, for example but not only, a cooling fluid containing droplets of oil to be removed.

In some forms of embodiment, the separator 10 can comprise a substantially cylindrical external shell 26, an entrance channel 1 1 for the gaseous stream to be treated, a passage pipe defined, in the solutions shown, by a filtering element 12, possibly of the replaceable type, of a tubular shape, and a diversion pipe 13, inside which the filtering element 12 is located, in this case coaxially, an outlet for the gaseous stream 24 and an outlet for the oil 23 located, respectively, above and below a lower end 17 of the diversion pipe 13.

The separator 10 also comprises a holed dividing plate 20, located below the lower end 17 of the diversion pipe 13, in order to complete the separation of the oil from the gas.

In forms of embodiment described here, the path is such as to obtain a passage of the gaseous stream in sections of increasing sizes, so as to allow a progressive slowing down of the gaseous stream in order to leave the droplets of oil enough time to separate from the gas.

In particular, the gaseous stream containing oil is introduced inside the separator 10 through the entrance channel 1 1, for example with a circular section, at a speed in general comprised between about 25 m/s and about 35 m/s, for example about 30 m/s.

Then, the gaseous stream is forced to pass through the filtering element 12, thus achieving a first purifying step by filtration, and is then introduced inside the diversion pipe 13.

The diversion pipe 13 is provided with a section, circular for example, of a bigger size than that associated with the entrance channel 1 1. This increase therefore allows to slow down the gaseous stream, whose speed can generally be comprised between about 5 m/s and about 10 m/s, for example about 8 m/s.

After passing through the diversion pipe 13, the gaseous stream exits from its lower end 17, thus occupying the whole section of the separator 10, of a greater size than the diversion pipe 13. A further slowing down of the gaseous stream is thus obtained, which can assume a speed comprised between about 0.3 m/s and about 1 m/s, for example about 0.5 m/s. The decelerations described above allow the gaseous stream to be treated to remain for longer in the zone near the lower end 17 of the diversion pipe 13, allowing a greater separation of the droplets of oil from the gaseous stream also due to the effect of gravitational pull, which is greater for the droplets of oil.

The separator 10 thus obtains a separation of the droplets of oil from the gaseous stream using different removal mechanisms: filtration, thanks to the presence of the filtering element 12; gravity, thanks to the greater density of the droplets of oil compared to the gas particles; and/or impact, thanks to the greater inertia of the droplets of oil that cannot follow the flow lines of the gas particles, and consequently impact against internal walls 19 of the external shell 26.

In forms of embodiment described here with reference to fig. 1, the entrance channel 1 1 can be located in the upper portion of the separator 10 and can have a filter holder 14 at its end, intended to support the filter element 12, possibly of the replaceable type and contained inside the diversion pipe 13.

In forms of embodiment described here for example with reference to fig. 2, the entrance channel 1 1 can extend as far as inside the diversion pipe 13, so as to make the gaseous stream pass through the filtering element 12 and, only afterward, exit from the lower part of the diversion pipe 13.

The filtering element 12 can comprise a micro-holed filtering mesh, of a rhomboid shape for example, with a diameter of the holes less than about 1 mm, for example comprised between about 0.3 mm and about 0.5 mm, in particular about 0.4 mm: the size must be such as to allow to retain most of the droplets of oil present in the gaseous stream to be treated, but avoiding high losses of load as the gaseous stream passes through the mesh.

Following filtration, the gaseous stream, following the path indicated by the arrows F, is retained in a channel 15 delimited by walls of the diversion pipe 13, and is subsequently conveyed to the outside of the diversion pipe 13 by means of the lower end 17.

In forms of embodiment described with reference to fig. 2, the lower end 17 of the diversion pipe 13 can be made non-symmetrically with respect to its vertical axis X.

In particular, the lower end 17 can be provided with an outlet zone 18, obtained by means of intersection of the diversion pipe 13 and a plane inclined according to an angle a with respect to the axis X of the diversion pipe 13 : the angle a is comprised between about 30° and about 60°, more in particular between about 40° and about 50°, for example about 45°.

The gaseous stream is then sent into the lower part of the separator 10 through the lower end 17, where the exit zone 18 allows to divert the normal path of the gaseous stream, about parallel to the axis X, according to the direction indicated by an arrow G, obtaining a substantial elbow-shaped inversion of the gaseous stream (fig. 1).

In this way, it is possible to obtain another purification, exploiting the greater inertia of the droplets of oil with respect to the gaseous stream: indeed, since these are not able to follow the same path as the gaseous stream because they are heavier, they impact against internal walls 19 of the external shell 26, falling downward and thus separating from the gaseous stream.

Finally, the droplets of oil are forced to pass through the holed dividing plate 20, which can have a group of holes with a diameter comprised between about 1 mm and about 2 mm, for example equal to about 1.5 mm, said holed dividing plate 20 being provided to prevent the separated droplets of oil from drawing the gas toward the bottom of the separator 10.

In a variant form of embodiment, described with reference to fig. 3, the entrance channel 1 1 1 of the gaseous stream can be provided in a lateral portion of the external shell 26, for example lower than the outlet of the gaseous stream 24. In this case, the entrance channel extends, with a substantially elbow-shaped path facing upward, as far as inside the diversion pipe 13. In this configuration, the gaseous stream is conveyed to the filtering element 12, supported by the filter holder 14, by an ascending motion, thus obliging it to pass through the filtering element 12 from the bottom to the top, and only afterward, to exit into the diversion pipe 13.

The droplets of oil, retained by the filtering element 12, tend to fall by gravity into the same entrance channel 1 1 1 , for example in its elbow-shaped zone, from which they can be removed by means of a stagnant oil discharge 27. In this case, there can be a manual or automatic evacuation, or a simple downward discharge, that is, toward the holed dividing plate 20. The droplets of oil that have been separated from the gaseous stream during the travel tend, by gravity, to collect toward the bottom of the separator 10, in particular, with reference to figs. 1 and 3, they can be deposited in a collection zone 21, from which the oil can be removed by means of a removal mean 22 and expelled through the oil outlet 23 : the removal mean 22 is, for example, a suction tube wound in concentric spirals so as to reduce the bulk (fig. 1).

On the contrary, since it is lighter, the purified gaseous stream rises upward, helped also by the specific conformation of the outlet zone 18, and can be removed through the gaseous stream outlet 24: the purified gaseous stream can be used without encountering problems connected to its performance.

In a variant form of embodiment described with reference to fig. 3, the oil removal mean 22 can be, for example, a curved dip tube, which removes the oil from the collection zone 21 and distances it from the separator 10 through the oil outlet 23 : the curved dip tube can have an angle of curvature comprised between about 35° and about 55°, for example about 45°.

In forms of embodiment described with reference to fig. 1, the separator 10 can also comprise in its upper portion a safety valve 25, which allows the gaseous stream to vent if there are particular critical conditions for the integrity of the separator 10, for example if there is a considerable increase in pressure because of a malfunctioning.

In a variant form of embodiment described with reference to fig. 3, the safety valve 25 can also be located for example in a lateral portion of the external shell 26, allowing in any case the exit of the gaseous stream if necessary.

It is clear that modifications and/or additions of parts may be made to the oil separator for cooling and/or air conditioning plants as described heretofore, without departing from the field and scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of oil separator for cooling and/or air conditioning plants, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

1. Oil separator for cooling and/or air conditioning plants including an external shell (26), an inlet channel (1 1, 111) for the gaseous stream to be treated, connected to said external shell (26), a filtering element (12) disposed in the transit path of the gaseous stream, an outlet for the purified gaseous stream (24) made in said external shell (26), and a collection zone (21) for the oil or other particles separated from said gaseous stream, said separator comprising a passage pipe connected to the inlet channel (1 1, 1 1 1) of the gaseous stream and to said filtering element (12), and a diversion pipe (13), disposed around said passage pipe, and defining an outlet zone (18) of the gaseous stream, disposed below said gaseous stream outlet (24) provided in the external shell (26), characterized in that said outlet zone (18) of the diversion pipe (13) is asymmetric with respect to a vertical axis (X) of the diversion pipe (13), and is obtained by means of an intersection between the diversion pipe (13) and a plane inclined by an acute angle (a) with respect to said axis (X).

2. Oil separator for cooling and/or air conditioning plants as in claim 1 , characterized in that the diversion pipe (13) is disposed coaxially with respect to the passage pipe, and has a greater diameter and length than the passage pipe.

3. Oil separator for cooling and/or air conditioning plants as in any claim hereinbefore, characterized in that it provides, below the diversion pipe (13), a holed dividing plate (20), in order to complete the separation of the oil from the gaseous stream.

4. Oil separator for cooling and/or air conditioning plants as in claim 3, characterized in that, in its lower part and below the holed dividing plate (20), it comprises said collection zone (21), from which the droplets of oil can be removed by means of a removal mean (22), connected to the oil outlet (23).

5. Oil separator for cooling and/or air conditioning plants as in any claim hereinbefore, characterized in that the diversion pipe (13) and the filtering element (12) are made in a single piece, substantially constituting a single element, said filtering element (12) being the replaceable type.

6. Oil separator for cooling and/or air conditioning plants as in any claim hereinbefore, characterized in that the filtering element (12) is connected to the inlet channel (11) by means of a filter holder (14), said inlet channel (1 1) extending as far as inside the diversion pipe (13), so as to oblige the gaseous stream to pass through the filtering element (12) and, only afterward, to exit from the diversion pipe (13).

7. Oil separator for cooling and/or air conditioning plants as in any claim hereinbefore, characterized in that the inlet channel (1 1) is provided in an upper portion of the external shell (26), above the outlet of the gaseous stream (24) and is connected to the upper part of the filtering element (12) to generate a stream entering from above and toward the bottom through said filtering element (12).

8. Oil separator for cooling and/or air conditioning plants as in any of the claims hereinbefore up to claim 6, characterized in that the inlet channel (111) is provided in a lateral portion of the external shell (26), below the outlet of the gaseous stream (24).

9. Oil separator for cooling and/or air conditioning plants as in claim 8, characterized in that said inlet channel (1 1 1) has an elbow conformation and is connected to the lower part of the filtering element (12) to generate a stream entering from the bottom toward the top through said filtering element (12).