EP2741029A2

EP2741029A2 - Oil separator

Info

Publication number: EP2741029A2
Application number: EP13196122.9A
Authority: EP
Inventors: Ken Watanabe; Takayuki Hattori; Takayuki Suzuki
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2012-12-10
Filing date: 2013-12-06
Publication date: 2014-06-11
Anticipated expiration: 2033-12-06
Also published as: EP2741029A3; JP2014115018A; TR201900560T4; JP6219032B2; EP2741029B1

Abstract

This oil separator including the following elements: a shell pipe (2) that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space; a gas inlet pipe (5) that introduces gas along a tangential direction of the cylindrical internal space; an approximately-linear oil return pipe (3) that guides oil separated in the cylindrical internal space to the outside; and an approximately-linear gas outlet pipe (4) that is opposed to the oil return pipe (3) and that guides gas separated in the cylindrical internal space to the outside, in which a central axis line (L2) of the gas outlet pipe (4) is provided eccentrically with respect to a central axis line (L1) of the shell pipe (2).

Description

Technical Field

The present invention relates to an oil separator that is suitable for use in a refrigerator or an air conditioner.

Background Art

There is a known centrifugal oil separator in which refrigerant oil contained in refrigerant discharged from a compressor is separated by centrifugation, thus separating gas-phase refrigerant and refrigerant oil.
In such a conventional oil separator, an appropriate positional relation between an outlet pipe and an inlet pipe is not defined. Thus, in a system in which a refrigerant flow rate changes depending on fluctuations between high pressure and low pressure in a refrigeration cycle caused by load fluctuation etc., or in a system in which the capacity of a compressor is controlled according to the load, even if an appropriate operation can be performed when the refrigerant flow rate is large, when the refrigerant flow rate is reduced, the whirling speed of refrigerant (gas) in the oil separator is reduced, which may reduce the efficiency of oil separation provided by a cyclone effect.
PTL 1 discloses a countermeasure for this.
PTL 1 discloses an oil separator including the following: a shell having a cylindrical part and a tapered part that is integrally formed at a lower portion of the cylindrical part and that is tapered downward; an outlet pipe that is inserted into the shell from an upper portion of the shell so as to be coaxial with the shell; a discharge pipe that is connected to an opening provided at a lower portion of the tapered part; and an inlet pipe that is connected along the tangential direction of an inner wall surface of the cylindrical part and through which a gas-liquid two-phase fluid flows into the shell, in which the distance between the opening and a shell side end portion of the outlet pipe is equal to or more than five times the inner diameter of the inlet pipe.
In the oil separator having the above-described structure, the inlet pipe has a straight pipe portion connected to the cylindrical part of the shell, and the length of the straight pipe portion is equal to or more than eight times the inner diameter of the inlet pipe; as a result, when the gas flow rate is small, the efficiency of oil separation can be improved at a low cost.

Citation List

Patent Literature

{PTL 1} Publication of Japanese Patent No. 4356214

Summary of Invention

Technical Problem

PTL 1 discloses the outlet pipe, which is inserted into the shell from the upper portion of the shell so as to be coaxial with the shell, and the discharge pipe, which is opposed to the outlet pipe. With the structure disclosed in PTL 1, because the outlet pipe and the discharge pipe are opposed to each other and coaxial with the shell, a pressure field produced by the flow in the shell tends to be point symmetrical as viewed in a transverse section of the shell, and a specific vibration tends to be excited.
Specifically, as shown in Fig. 6, a mixture fluid of refrigerant gas and oil is supplied from a gas inlet pipe 5 and is separated into gas and oil in the shell pipe 2.
At this time, as shown in Fig. 7, a pressure field 6 tends to be formed in the refrigerant flow flowing in and around a center portion of the shell pipe 2. Because the pressure field 6 is formed into a ring shape (point symmetry) as viewed in a transverse section of the shell pipe 2, a specific vibration mode tends to be excited.
Furthermore, pressure fluctuation tends to occur between an inner circumferential side and an outer circumferential side of the pressure field 6. Thus, if the pressure fluctuation occurs continuously at the same place in the shell pipe 2, the specific vibration generated by the pressure fluctuation is transferred to the pipes, thus causing resonance and noise.
The present invention has been made in view of such circumstances, and an object thereof is to provide an oil separator that prevents the occurrence of resonance by preventing a specific vibration in the shell pipe.

Solution to Problem

In order to solve the above-described problems, the oil separator of the present invention employs the following solutions.
A first aspect of the present invention provides an oil separator comprising the following elements: a housing (shell pipe) that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space; a gas inlet pipe that introduces gas to the shell pipe along a tangential direction of the cylindrical internal space; an approximately-linearly-formed oil return pipe that guides the oil separated in the cylindrical internal space to the outside; and an approximately-linearly-formed gas outlet pipe that is located oppositely to the oil return pipe and that guides gas separated in the cylindrical internal space to the outside, wherein a central axis line of the gas outlet pipe is provided eccentrically with respect to a central axis line of the shell pipe.
With the first aspect of the present invention, the gas outlet pipe is provided eccentrically with respect to the central axis line of the shell pipe. Thus, the flow and the pressure field in the shell pipe can be prevented from being point symmetrical. Thus, excitation of a specific vibration mode can be prevented. As a result, vibrations in the shell pipe can be prevented, and then the occurrence of resonance in the shell pipe can be prevented. Therefore, noise can be prevented from occurring.
Furthermore, a second aspect of the present invention provides an oil separator comprising the following elements: a shell pipe that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space; a gas inlet pipe that introduces gas to the shell pipe along a tangential direction of the cylindrical internal space; an approximately-linearly-formed oil return pipe that guides the oil separated in the cylindrical internal space to the outside; and an approximately-linearly-formed gas outlet pipe that is located oppositely to the oil return pipe and that guides the gas separated in the cylindrical internal space to the outside, wherein an open end surface of a tip portion of the gas outlet pipe that is located inside the shell pipe is configured so as to form an angle with respect to a plane perpendicular to a central axis line of the shell pipe.
With the second aspect of the present invention, the open end surface of the tip portion of the gas outlet pipe, which is located inside the shell pipe, is configured so as to form an angle with respect to a plane perpendicular to the central axis line of the shell pipe. Thus, the flow of suctioned gas from the open end surface of the tip portion can be made uneven. Therefore, even though the gas outlet pipe is provided concentrically with respect to the central axis line of the shell pipe, the flow and the pressure field in the shell pipe can be prevented from being point symmetrical. Thus, vibrations in the shell pipe can be prevented, and then the occurrence of resonance in the shell pipe can be prevented.
Furthermore, a third aspect of the present invention provides an oil separator comprising the following elements: a shell pipe that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space; a gas inlet pipe that introduces gas to the shell pipe along a tangential direction of the cylindrical internal space; an approximately-linearly-formed oil return pipe that guides the oil separated in the cylindrical internal space to the outside; and an approximately-linearly-formed gas outlet pipe that is located oppositely to the oil return pipe and that guides the gas separated in the cylindrical internal space to the outside, wherein the gas outlet pipe is provided such that a central axis line of the gas outlet pipe is inclined with respect to a central axis line of the shell pipe.
With the third aspect of the present invention, the gas outlet pipe is provided so as to be inclined with respect to the central axis line of the shell pipe. Thus, even though the gas outlet pipe is provided concentrically with respect to the central axis line of the shell pipe, the flow and the pressure field in the shell pipe can be prevented from being point symmetrical. Thus, vibrations in the shell pipe can be prevented, and then the occurrence of resonance in the shell pipe can be prevented.
Furthermore, a fourth aspect of the present invention provides an oil separator comprising the following elements: a shell pipe that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space; a gas inlet pipe that introduces gas to the shell pipe along a tangential direction of the cylindrical internal space; an approximately-linearly-formed oil return pipe that guides the oil separated in the cylindrical internal space to the outside; and a gas outlet pipe that is located oppositely to the oil return pipe and that guides the gas separated in the cylindrical internal space to the outside, wherein a tip portion of the gas outlet pipe is curved so that the tip portion of the gas outlet pipe has a predetermined angle with respect to a central axis line of the shell pipe.
With the fourth aspect of the present invention, the tip portion of the gas outlet pipe is curved with respect to the central axis line of the shell pipe. Thus, even though the gas outlet pipe is provided concentrically with respect to the central axis line of the shell pipe, the flow and the pressure field in the shell pipe can be prevented from being point symmetrical. Thus, vibrations in the shell pipe can be prevented, and then the occurrence of resonance in the shell pipe can be prevented.

Advantageous Effects of Invention

According to the oil separator of the present invention, the position and the shape of the gas outlet pipe are not aligned with the central axis line of the shell pipe. Thus, the flow and the pressure field in the shell pipe can be prevented from being point symmetrical. Thus, excitation of a specific vibration mode can be prevented. Furthermore, vibrations in the shell pipe can be prevented, and then the occurrence of resonance in the shell pipe can be prevented. Therefore, noise can be prevented from occurring.

Brief Description of Drawings

{Fig. 1} Fig. 1 is a perspective view showing, in outline, a configuration of an oil separator according to a first embodiment of the present invention.
{Fig. 2} Fig. 2 is a sectional side view showing the oil separator according to the first embodiment of the present invention.
{Fig. 3} Fig. 3 is a sectional side view showing an oil separator according to a second embodiment of the present invention.
{Fig. 4} Fig. 4 is a sectional side view showing a modification of the oil separator according to the second embodiment of the present invention.
{Fig. 5} Fig. 5 is a sectional side view showing a modification of the oil separator according to the second embodiment of the present invention.
{Fig. 6} Fig. 6 is a horizontal sectional view showing a reference-example oil separator.
{Fig. 7} Fig. 7 is a horizontal sectional view showing a reference-example pressure field produced in a shell pipe.

Description of Embodiments

First Embodiment

An oil separator according to a first embodiment of the present invention will be described below with reference to Figs. 1 and 2.
Fig. 1 is a perspective view showing, in outline, a configuration of an oil separator 1 of this embodiment. The oil separator 1 is used in a refrigerator or an air conditioner. The oil separator 1 is provided with a shell pipe 2, an oil return pipe 3, a gas outlet pipe 4, and a gas inlet pipe 5.
The shell pipe 2 of the oil separator 1 is formed in a cylindrical shape. Furthermore, a cylindrically-formed internal space is provided inside the shell pipe 2. The gas inlet pipe 5 that introduces gas is inserted into the shell pipe 2 along the tangential direction of the cylindrical internal space. The gas inlet pipe 5 is provided on a side portion of the shell pipe 2 when viewed in the axial direction of the shell pipe 2.
Furthermore, the approximately-linearly-formed oil return pipe 3 that guides oil separated in the internal space of the shell pipe 2 to the outside is connected to a lower surface of the shell pipe 2. Furthermore, the approximately-linearly-formed gas outlet pipe 4 that is disposed so as to be opposed to the oil return pipe 3 and that guides gas separated in the internal space of the shell pipe 2 to the outside is provided through an upper surface of the shell pipe 2.
As shown in Fig. 1, the centrifugal oil separator 1 is provided with the gas inlet pipe 5, through which a mixture fluid of refrigerant gas and oil is supplied from a compressor (not shown) located near the shell pipe 2, and the gas outlet pipe 4, through which only the separated gas flows out. Furthermore, the oil return pipe 3, through which oil separated from the gas flows out, is connected to a bottom portion of the shell pipe 2.
As shown in Fig. 2, the central axis line L2 of the gas outlet pipe 4 provided in the shell pipe 2 is provided so as to be eccentric with respect to the central axis line L1 of the shell pipe 2. Regarding the eccentric distance between the central axis line L1 and the central axis line L2, when the diameter of the shell pipe 2 is 50 mm, and the diameter of the gas outlet pipe 4 is 15 mm, for example, the central axis line L2 of the gas outlet pipe 4 is provided 2 mm to 3 mm eccentrically with respect to the central axis line L1 of the shell pipe 2.
Next, the operation of the oil separator 1 having the above-described structure will be described below.
While the compressor (not shown) is operated, a mixture fluid of gas and oil flowing out from the compressor through the gas inlet pipe 5 collides with an inner wall surface of the cylindrical shell pipe 2, and the mixture of gas and oil is rotated at high speed along the inner wall surface of the cylindrical shell pipe 2. The oil is centrifugally pushed against the inner wall surface of the shell pipe 2 and is separated, and the gas flows out through the gas outlet pipe 4.
On the other hand, the oil drips down along the inner wall surface of the shell pipe 2, the dripped oil flows into the oil return pipe 3 from a junction point of the oil return pipe 3 and the shell pipe 2, and the oil returns to a suction pipe of the compressor (not shown).
According to this embodiment, the following advantageous effect can be achieved.
As shown in Fig. 2, the central axis line L2 of the gas outlet pipe 4 is provided eccentrically with respect to the central axis line L1 of the shell pipe 2. Thus, a pressure field 6 (see Fig. 6) produced by the flow in the shell pipe 2 is prevented from being point symmetrical. Furthermore, by providing the central axis lines L1 and L2 eccentrically, the pressure field 6 can be prevented from being produced.
Thus, vibrations in the shell pipe 2 can be prevented, and then the occurrence of resonance in the shell pipe can be prevented. Therefore, noise can be prevented from occurring.

Second Embodiment

Next, a second embodiment of the present invention will be described with reference to Figs. 3 to 5.
In this embodiment, the central axis line L2 of the gas outlet pipe 4, which is inserted into the shell pipe 2 shown in the first embodiment, and the central axis line L1 of the shell pipe 2 are concentrically provided. Identical symbols are assigned to the corresponding structures of the first embodiment, and a description thereof will be omitted.
As shown in Fig. 3, the central axis line L1 of the shell pipe 2 and the central axis line L2 of the gas outlet pipe 4 are concentric.
An open end surface of a tip portion 4a of the gas outlet pipe 4 that is located inside the shell pipe 2 is formed so as to form an angle with respect to a plane perpendicular to the central axis line L1 of the shell pipe 2. The angle of inclination of the tip portion 4a is set to 45 degrees, for example, or may be set larger or smaller than 45 degrees. By providing the tip portion 4a of the gas outlet pipe 4 with an angle of inclination, suctioning gas from the tip portion 4a differs between both ends of the tip portion 4a.
According to this embodiment, the flow of suctioned gas from the open end surface of the tip portion 4a of the gas outlet pipe 4 can be made uneven. Therefore, even though the central axis line L2 of the gas outlet pipe 4 is provided concentrically with respect to the central axis line L1 of the shell pipe 2, it is possible to prevent the pressure field 6 (see Fig. 6), which can be produced by the flow in the shell pipe 2, from being point symmetrical. Thus, vibrations in the shell pipe 2 can be prevented, and then the occurrence of resonance in the shell pipe can be prevented.
Furthermore, because the central axis line L2 of the gas outlet pipe 4 is provided concentrically with respect to the central axis line L1 of the shell pipe 2, manufacturing process can be reduced compared with a case in which they are eccentrically provided.
Note that the following modification can be adopted in the second embodiment.
Fig. 4 is a sectional side view showing a modification of the oil separator 1 of the second embodiment of the present invention. As shown in Fig. 4, the gas outlet pipe 4 is provided in the shell pipe 2 so as to extend across the central axis line L1 of the shell pipe 2 and so as to be inclined with respect to the central axis line L1.
Because the gas outlet pipe 4 is inclined with respect to the central axis line L1 of the shell pipe 2, even though the gas outlet pipe 4 is provided concentrically with respect to the central axis line L1 of the shell pipe 2, it is possible to prevent the flow in the shell pipe and the pressure field from being point symmetrical. Thus, vibrations in the shell pipe can be prevented, and then the occurrence of resonance in the shell pipe can be prevented.
Furthermore, the following modification can be adopted in the second embodiment.
Fig. 5 is a sectional side view showing a modification of the oil separator 1 of the second embodiment of the present invention. As shown in Fig. 5, a tip portion 4b of the gas outlet pipe 4 in the shell pipe 2 is curved so as to have a predetermined angle with respect to the central axis line L1 of the shell pipe 2. The predetermined angle is set to an angle at which the central axis line L1 of the shell pipe 2 is located outside an opening of the tip portion 4b, for example.
The tip portion 4b of the gas outlet pipe 4 is curved with respect to the central axis line L1 of the shell pipe 2. Furthermore, the gas outlet pipe 4 is provided concentrically with respect to the central axis line L1 of the shell pipe 2. Thus, the flow in the shell pipe 2 and the pressure field (see Fig. 6) can be prevented from being point symmetrical. Specifically, because vibrations in the shell pipe 2 can be prevented, the occurrence of resonance in the shell pipe can be prevented.

Reference Signs List

1 oil separator
2 shell pipe
3 oil return pipe
4 gas outlet pipe
4a tip portion
4b tip portion
5 gas inlet pipe
6 pressure field
L1 central axis line (shell pipe)
L2 central axis line (gas outlet pipe)

Claims

An oil separator comprising:
a shell pipe (2) that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space;

a gas inlet pipe (5) that introduces gas to the shell pipe (2) along a tangential direction of the cylindrical internal space;

an approximately-linearly-formed oil return pipe (3) that guides the oil separated in the cylindrical internal space to the outside; and

an approximately-linearly-formed gas outlet pipe (4) that is located oppositely to the oil return pipe and that guides the gas separated in the cylindrical internal space to the outside,

wherein a central axis line (L2) of the gas outlet pipe (4) is provided eccentrically with respect to a central axis line (L1) of the shell pipe (2).
An oil separator comprising:
a shell pipe (2) that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space;

a gas inlet pipe (5) that introduces gas to the shell pipe (2) along a tangential direction of the cylindrical internal space;

an approximately-linearly-formed oil return pipe (3) that guides the oil separated in the cylindrical internal space to the outside; and

an approximately-linearly-formed gas outlet pipe (4) that is located oppositely to the oil return pipe and that guides the gas separated in the cylindrical internal space to the outside,

wherein an open end surface of a tip portion (4a) of the gas outlet pipe that is located inside the shell pipe (2) is configured so as to form an angle with respect to a plane perpendicular to a central axis line (L1) of the shell pipe (2).
An oil separator comprising:
a shell pipe (2) that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space;

a gas inlet pipe (5) that introduces gas to the shell pipe (2) along a tangential direction of the cylindrical internal space;

an approximately-linearly-formed oil return pipe (3) that guides the oil separated in the cylindrical internal space to the outside; and

an approximately-linearly-formed gas outlet pipe (4) that is located oppositely to the oil return pipe (3) and that guides the gas separated in the cylindrical internal space to the outside,

wherein the gas outlet pipe (4) is provided such that a central axis line (L2) of the gas outlet pipe (4) is inclined with respect to a central axis line (L1) of the shell pipe (2).
An oil separator comprising:
a shell pipe (2) that has a cylindrical internal space and that separates gas and oil in the cylindrical internal space;

a gas inlet pipe (5) that introduces gas to the shell pipe (2) along a tangential direction of the cylindrical internal space;

an approximately-linearly-formed oil return pipe (3) that guides the oil separated in the cylindrical internal space to the outside; and

a gas outlet pipe (4) that is located oppositely to the oil return pipe (3) and that guides the gas separated in the cylindrical internal space to the outside,

wherein a tip portion (4b) of the gas outlet pipe (4) is curved so that the tip portion (4b) of the gas outlet pipe has a predetermined angle with respect to a central axis line (L1) of the shell pipe (2).