Patent Grant
11213831
The present invention relates to centrifugal separators having a device for the transformation of kinetic energy of a liquid rotating in an outlet chamber around a rotational axis to pressure energy. This device comprises an element for the discharge of liquid out of said outlet chamber, which element has a radially outer part shaped as a body of revolution about the rotational axis and arranged to be located in a rotating liquid body in said outlet chamber, at least one outlet channel formed in the element and having an inlet opening located in a surface of the body of revolution and elongated in the liquid flow direction, the inlet opening connecting to the interior of an outlet tube via said outlet channel.
In a centrifugal separator which provided with an energy transformation device of the above form, parts of the rotor of the centrifugal separator form an outlet chamber, in which the liquid rotates. The outlet chamber is arranged to receive a separated liquid continuously from the separation chamber of the centrifugal rotor. This liquid forms a rotating liquid body in the outlet chamber. Centrally in the outlet chamber an outlet device is arranged, through which liquid is discharged out of the outlet chamber and further out of the centrifugal rotor. A centrifugal separator of this kind is shown in EP 0404923, for instance.
In many cases it is important that the energy transformation device can transform as much as possible of the energy stored in the rotating liquid to pressure energy. The maximum pressure which can be achieved is determined by the equation of Bernoulli for the pressure along a flow line of the liquid.
P stat+P dyn=constant
The static pressure P stat at the inlet opening is composed of the pressure from the part of the rotating liquid body, which is located radially inside the inlet opening, and the pressure which acts on this part of the liquid body.
The dynamic pressure P dyn is in each point along a flow line determined by the equation
P dyn=½ρW2
in which ρ is the density of the liquid and W being the flow rate of the liquid at the point looked upon.
Outside the inlet opening the liquid has a total pressure which is the sum of the static and dynamic pressure there. However, in the device in a centrifugal separator known by EP 0 404 923 much of the pressure is lost in the bend where the flow direction changes from mainly horizontal to mainly axial.
The object of the present invention is to provide a centrifugal separator having a device of the kind initially described for the transformation of kinetic energy of a rotating liquid to pressure energy, which device can recover a greater part of the static and the dynamic pressure in the rotating liquid than previously known such devices without involving an increasing risk for the admixture of air in the liquid, and with minimal pressure loss at said change from horizontal, radial to axial flow direction.
It is provided a centrifugal separator having a device for the transformation of kinetic energy of a liquid rotating in a chamber around a rotational axis to pressure energy, comprising an element for the discharge of liquid out of the chamber, which element has a radially outer part shaped as a body of revolution about the rotational axis and arranged to be located in the rotating liquid body, at least one outlet channel formed in the element and having an inlet opening located in a surface of the body of revolution and elongated in the liquid flow direction, the inlet opening connecting to the interior of an outlet tube via said outlet channel, wherein said outlet channel having a defined axial height (h) and a defined width (w) and wherein a defined aspect ratio h/w being larger than 1 in an outer first part of said outlet channel and decreasing to smaller than 1 in an inner second part of said outlet channel and wherein the axial height (h) decreases inwardly along the length of said outlet channel.
The cross-sectional area of the outlet channel is constant or increases along the outlet channel in the direction of flow therethrough.
To make the entrance to the channel effective the h/w is set larger >1 at entrance, preferable in the interval 1.5 to 2. To make the transformation of kinetic energy to pressure effective the channel cross section should be not increased too fast. Also, the flow path change direction from horizontal, mainly radial to mainly axial at the connection between paring disc and the axial outlet channel. The radial extension of the axial channel (ΔR) is for number of practical reasons kept small. In the bend h transforms into ΔR, where ΔR is smaller than h. To make the transition horizontal, radial to axial with minimized pressure loss, h is reduced along flow path in the horizontal, radial part of the channel, while w is gradually increased in such rate that the channel cross section area is constant or gradually increasing. This allows to make the curvature of the bend from horizontal, radial to axial larger as measured relative channel heights or ΔR. This reduces pressure loss at bend horizontal, radial to axial.
One execution is to extend the diffusor to the axial part of the channel.
Said aspect ratio may decrease from between 1.25-2.00 to 0.25-0.75.
Said aspect ratio may decrease from between 1.50-2.00 to 0.40-0.60.
Said decrease may be in an inner second part of said outlet channel, wherein said inner second part is attached to the said outlet tube.
Said inner second part may be extending essentially straight radially inwardly.
The outlet tube may be arranged coaxially around a stationary axial inlet tube.
The inner second part of the outlet channel attaches to the outlet tube by a bend directed upwards with a radius R1.
The height (h) of the outlet channel may decrease by an upper wall of outlet channel which is sloping inwardly along the length of said outlet channel.
Said element may have 2 to 8 outlet channels.
Said element may have 4 to 7 outlet channels.
The cross-sectional area of the outlet channel may gradually increase along the outlet channel in the direction of flow therethrough.
Said cross section of the outlet channel may be substantially rectangular.
Said inlet opening may be formed in an essentially radially facing surface of the element.
The inlet opening may be of one of the following shapes: triangular, NACA duct profile or rectangular shape.
Further aspects of the invention are apparent from the dependent claims and the description.
Further objects, features and advantages will appear from the following detailed description of several embodiments of the invention with reference to the drawings, in which:
A centrifugal separator shown in
Inside the separation chamber 5 there is arranged a disc stack 10 consisting of a number of conical separation discs held between a distributor 11 and the upper part 2. The upper part forms at its upper end, as shown in the figure, a ring-formed chamber 12 around the rotational axis, into which chamber 12 in this case a specific lighter liquid component of the mixture can flow from the separation chamber 5 via an inlet 13. The liquid present in the chamber 12 during operation of the rotor forms a rotating liquid body having a radially inwards facing free liquid surface 14.
Centrally through the chamber 12 a stationary inlet tube 15 extends axially, which delivers fluid to be separated into the separation chamber. Around the inlet tube 15 there is arranged a stationary coaxial outlet tube 16 for the specific lighter liquid component collected in the chamber 12.
In the chamber 12, a device for the transformation of kinetic energy of liquid rotating in the chamber 12 to pressure energy is arranged, comprising a discharge element 17, for the discharge of liquid out of the chamber 12, arranged around the inlet tube 15 and connected to the outlet tube 16. The discharge element 17 is stationary but in an alternative outlet arrangement a similar outlet element can be arranged to rotate with a rotational speed which is lower than the rotational speed of the rotor.
The discharge element 17 extends radially outwards and has outside the radial level of the free liquid surface 14 of the rotating liquid body a part, which has at least one inlet opening 18. This inlet opening 18 is connected to the interior of the outlet tube 16 via an outlet channel 19 formed in the discharge element 17. The inlet opening 18 can be of a triangular, NACA duct profile, rectangular or other shape.
The discharge element 17 shown in
The outlet channel 19 has a defined height h and a defined width w which vary along its extension from its inlet opening 18 to its connection to said outlet tube 16. The height and the width may be used to define an aspect ratio h/w which thus also vary along the channel extension. It has been discovered that the aspect ratio, and especially the variation of the aspect ratio has an impact on the pressure loss in the discharge element. In
The outlet channel 19 comprises an outer first part 19a extending circumferentially in the rotational direction with a slight curve inwardly, growing in abruptness, and said inner second part 19b attached to the outer first part 19a. The inner second part 19b is extending essentially straight radially inwardly.
The aspect ratio h/w is larger than 1 in said outer first part 19a of said outlet channel 19 and decreases to smaller than 1 in said inner second part 19b of said outlet channel 19. The height (h) decreases inwardly along the length of said outlet channel 19.
The aspect ratio may decrease from between 1.25-2.00 to 0.25-0.75, preferably from between 1.50-2.00 to 0.40-0.60.
As can be seen in
In order to further bring down pressure losses and unwanted mechanical impact on the streaming liquid the inner second part 19a of the outlet channel 19 is attached to the outlet tube 16 by a smooth direction change from radial to axial.
The inner second part 19b of the outlet channel 19 attaches to the outlet tube 16 by a bend directed upwards with a radius R1. The height (h) of the outlet channel 19 decreases by an upper wall 19c of the outlet channel 19 which is sloping inwardly along the length of said outlet channel 19.
To make the entrance to the channel effective the h/w is set larger >1 at entrance, preferable in the interval 1.5 to 2. To make the transformation of kinetic energy to pressure effective the channel cross section should be not increased too fast. Also, the flow path change direction from horizontal, mainly radial to mainly axial at the connection between paring disc and the axial outlet channel. The radial extension of the axial channel (ΔR) is for number of practical reasons kept small. In the bend h transforms into ΔR, where ΔR is smaller than h. To make the transition horizontal, radial to axial with minimized pressure loss, h is reduced along flow path in the horizontal, radial part of the channel, while w is gradually increased in such rate that the channel cross section area is constant or gradually increasing. This allows to make the curvature of the bend from horizontal, radial to axial larger as measured relative channel heights or ΔR. This reduces pressure loss at bend horizontal, radial to axial.
Said discharge element 17 may have one outlet channel 19 as is disclosed in
The cross-sectional area of the outlet channel 19 may be chosen to gradually increase along the outlet channel 19 in the direction of flow therethrough.
The cross section of the outlet channel 19 may be substantially rectangular. Other cross section configurations may be possible like triangular, multi-angled or other shapes.
The discharge element 17 may consist of a circular cylindrical disc.
The inlet opening 18 may have triangular, NACA duct profile or rectangular shape but other shapes may be possible.
Said inlet opening 18 is formed in an essentially radially facing surface of the discharge element 17.
In
In
By designing a centrifugal separator having an energy transformation device as described in the above embodiments, the kinetic energy of the rotating liquid can be recovered and transformed into pressure energy much more effectively than has been previously possible.
In all the embodiments described above the inlet openings are formed in a circular cylindrical surface and facing radially. However, the invention is also applicable to devices having inlet openings which face in another direction, for instance axially.
The invention is not limited to the embodiments described above and shown on the drawings, but can be supplemented and modified in any manner within the scope of the invention as defined by the enclosed claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18179557 | Jun 2018 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/065387 | 6/12/2019 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2020/001981 | 1/2/2020 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2125453 | Hans | Aug 1938 | A |
| 2171136 | Bergner | Aug 1939 | A |
| 2230210 | Brecour et al. | Jan 1941 | A |
| 5147280 | Carlsson et al. | Sep 1992 | A |
| 5160311 | Inge | Nov 1992 | A |
| 7041045 | Thiemann | May 2006 | B2 |
| 9358554 | Pitkämäki et al. | Jun 2016 | B2 |
| 20040242395 | Thiemann | Dec 2004 | A1 |
| 20140051563 | Mackel et al. | Feb 2014 | A1 |
| 20140341714 | Casa | Nov 2014 | A1 |
| 20150175439 | Quiter et al. | Jun 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 1426843 | Jul 2003 | CN |
| 101415499 | Apr 2009 | CN |
| 103153474 | Jun 2013 | CN |
| 104582857 | Apr 2015 | CN |
| 101 43 405 | Apr 2003 | DE |
| 0 404 923 | Jan 1991 | EP |
| 1323477 | Jul 2003 | EP |
| WO 9007983 | Jul 1990 | WO |
| WO 2007114766 | Oct 2007 | WO |
| Entry |
|---|
| “Centrifugal seperators and milk standardization”, Dairy Processing Handbook, Chapter 6.2, prior to Aug. 22, 2017, URL: http://dairyprocessinghandbook.com/chapter/centrifugal-separators-and-milk-standardization. |
| International Preliminary Report on Patentability, issued in PCT/EP2019/065387, dated Apr. 24, 2020. |
| International Search Report, issued in PCT/EP2019/065387, dated Aug. 28, 2019. |
| Written Opinion of the International Searching Authority, issued in PCT/EP2019/065387, dated Aug. 28, 2019. |
| English translations of the Chinese Office Action and Search Report, dated Apr. 26, 2021, for Chinese Application No. 201980042494.0. |
| Number | Date | Country | |
|---|---|---|---|
| 20210245176 A1 | Aug 2021 | US |
