DE102017111366A1 - Variable Area Flowmeter - Google Patents

Abstract

The invention relates to a variable area flowmeter (1) for determining and / or monitoring a flow of a medium directed against gravity in a vertically extending fluid line (2), comprising: a guide (3) with a conically opening in the flow direction (RD) Section (4), and arranged in the guide float (5) which is designed such that between the inner wall (31) of the guide (3) and the outer surface (51) of the float (5) a the float (5) surrounding free space (6) is present, and that the outer surface (51) of the float (5) has a channel-shaped and in the flow direction (RD) continuous groove (7). The invention further relates to an analyzer (20) having a variable area flowmeter (1) according to the invention.

Description

The invention relates to a variable area flowmeter for determining and / or monitoring an anti-gravity flow of a medium in a vertically extending fluid line, comprising a guide with a conically opening in the flow direction section, and a floating body arranged in the guide.

The measurement principle of a variable area flowmeter is based on the float experiencing an anti-gravity force in response to an anti-gravity flow in a vertical fluid conduit. This is composed of the buoyancy force and the flow resistance force. If the force directed against the force of gravity is greater than the weight force of the float, the float is lifted in the guide which opens conically in the flow direction. With increasing height of the float in the guide thus increases a present between the inner wall of the guide and the outer surface of the float, surrounding the floating space. This in turn reduces the flow resistance force. Thus, the float rises only until there is a balance of power between the force caused by the flowing medium and the weight. In the stationary case, the height of the floating float in the guide thus represents a measure of the flow. Float flowmeters require in principle no power supply during operation. They are described in the art in a variety of publications, including, for example, in the patent DE 196 24 974 C1 ,

In the event that the medium is a non-homogeneous medium, for example with foreign bodies contained in the medium and / or air bubbles, known from the prior art variable area flowmeters are prone to failure. For example, air bubbles, which can not pass the float, accumulate below the float. As a result, the buoyancy force is increased so that an erroneously high flow rate is displayed. In the extreme case, even with a flow rate of zero, the float remains suspended through the air bubbles, so that a flow is indicated, even if there is no flow. This case is particularly problematic when the variable area flowmeter is used as a limit switch to monitor the presence of a predetermined minimum flow to be provided.

The use of variable area flowmeters as limit switches occurs, for example, in fluid lines of analyzers, particularly in on-line analyzers for analyzing a sample of a medium. Examples of online analyzers are in the DE 10 2012 102 256 A1 , of the DE 102 22 822 A1 , of the DE 102 27 032 A1 and the DE 10 2009 029 305 A1 called. In this case, the variable area flowmeters can be used to determine and / or monitor the flow in fluid lines, for example to control and / or regulate a delivery and / or metering device.

The invention is therefore based on the object to provide a float flow meter, which reliably measures the flow even with inhomogeneous media.

The object is achieved by a variable area flowmeter for determining and / or monitoring a counter to the gravity flow of a medium in a vertically extending fluid line, comprising a guide with a conically opening in the flow direction section, and arranged in the guide float, the is configured such that between the inner wall of the guide and the outer surface of the float is a free space surrounding the float, and that the outer surface of the float has a channel-shaped and continuous in the flow direction groove.

The great advantage of the solution according to the invention is that by means of the groove any air bubbles and / or possibly other foreign bodies otherwise accumulating below the float can flow freely past the float in the channel-shaped and in the flow direction continuous groove.

The channel-shaped and in the flow direction continuous groove is introduced into the outer surface, such as by a special machining of the outer surface of the float. Alternatively, the float having the groove is produced in a primary molding process. "Continuous flow direction" means in the context of this application, that by means of the channel-shaped groove a continuous channel between an area below the float and an area above the float is present, in principle, there are no restrictions on the specific shape of the channel-shaped groove. The free space surrounding the floating body completely surrounds the floating body in at least one sectional plane transversely to the direction of flow.

In this case, the groove is advantageously dimensioned in particular so that the diameter of in the Medium present air bubbles smaller than the groove present by the additional space between the inner wall of the guide and the outer surface of the float is. As "additional free space" here is the conditional by the groove clearance between the inner wall of the guide and the outer surface of the float, ie in comparison to an otherwise identically designed float without groove.

It is advantageous that the float is arranged with a longitudinal axis parallel to the vertically extending guide or to the flow direction.

In one embodiment of the invention, the groove is dimensioned such that the mass of the float between 1% to 20% is smaller than the mass of an otherwise identically designed floating body without groove.

Preferably, the mass of the float is between 2% to 10% smaller than the mass of an otherwise identical designed floating body without groove.

In a particularly advantageous development of the variable area flowmeter, the guide has a cylindrical section, which is arranged in front of the conical section with respect to the flow direction. In particular, the cylindrical section of the guide is thus arranged below the conical section. In this case, the free space between the inner wall of the guide and the outer surface of the float is also present in the cylindrical section of the guide of the float surrounding the floating body. At zero flow, the float will not rise; It therefore initially rests in the cylindrical section, for example on a support arranged on a supply line of the flow in the guide, so that the free space initially exists only between the laterally arranged outer surfaces of the float and the inner wall of the guide.

It is advantageous if the cylindrical section is located immediately before the conical section, i. without any further intermediate section disposed between the two sections and when there is a substantially continuous transition between the two sections. Then, for example, the initial diameter in the conical portion corresponds to the diameter of the cylinder-shaped portion immediately upstream in the flow direction. Since the diameter increases continuously in the vertical flow direction in the conical section, the diameter in the conical section is always larger than in the cylindrical section.

Now, if a flowing medium is passed into the guide, the flow or flow rate is large enough to lift the float, the float is raised in the cylindrical portion of the guide with an initial stroke, namely until the float reaches the conical section. Such an initial stroke is particularly advantageous if the measuring range of the variable area flowmeter includes particularly small flow rates, for example, flows or flow velocities of less than 1 ml / s.

Since, in particular for small flows to be determined and / or monitored, the initially mentioned air bubbles are particularly problematic, in this development, i. the combination of the floating body according to the invention with the groove and the guide with the transition from the cylindrical portion to the conical portion, particularly strong synergy effects before.

In principle, however, the solution described in this development is also to be regarded as independent of the groove included in the solution according to the invention, since the initial stroke caused by the guidance with the transition from the cylindrical section to the conical section is in itself advantageous for a floating body. Flowmeter is that is designed to measure very small flows.

The sensitivity of the variable area flowmeter is adjusted from the free gap surface transverse to the flow direction between the float and the guide in the cylindrical portion, in particular the ratio of the mass of the float in relation to the free gap surface, as well as the configuration of the conical section.

In an advantageous embodiment of the variable area flowmeter, the float is dimensioned with respect to the guide such that in the cylindrical portion in a sectional plane transverse to the flow direction between the guide and the float disposed therein a gap surface is present, which is greater than a predetermined Spaltflächen- Minimum value is. The gap area minimum value is in particular 0.5 mm ² and preferably 2 mm ² .

In a further advantageous embodiment of the invention, the float is dimensioned in relation to the guide such that in the cylindrical portion in a sectional plane transverse to the flow direction between the guide and the float disposed therein a gap surface is present, the quotient of the mass of the Float divided by the gap surface is smaller than a predetermined quotient maximum value. The quotient maximum value is in particular 3 g / mm ² and preferably 1.4 g / mm ² .

By such a dimensioning of the float a very high sensitivity is achieved, so that the above-mentioned small flow rates of up to less than 1ml / s can be measured with the float flowmeter according to the invention.

In an advantageous embodiment of the invention, the cylindrical portion of the guide is at least 10%, in particular at least 20% of the length of the guide.

In a further advantageous embodiment of the invention, the conical portion of the guide is at least 20%, in particular at least 30% of the length of the guide.

It is advantageous if the conical section of the guide is longer than the cylindrical section causing the initial stroke, in particular by at least 10%, preferably by at least 20%, of the length of the guide.

In an advantageous embodiment of the invention, the channel-shaped groove extends substantially parallel to the flow direction. In this case, it is therefore a straight groove, which runs along a longitudinal axis of the float, so that the air bubbles passing through the floating body is as short as possible the distance covered by the channel-shaped groove.

In a further embodiment of the invention, the groove has a substantially V-shaped or U-shaped profile.

In the case of a V-shaped profile, it is advantageous if the V-shaped profile has an opening angle between 60 ° and 120 °, in particular between 80 ° and 100 °.

It is advantageous if the groove has a maximum groove depth which is between 0.5 and 3 mm. It is also advantageous if the groove has a maximum groove depth which is between 10 and 30% of the diameter of the float.

In particular, it is furthermore advantageous for the invention if the float does not have more than one groove. With just one groove, a slight asymmetry is introduced into the float. So that the float can still stably float in the guide, and e.g. not jammed by an imbalance, the float must be sufficiently long along its longitudinal axis (i.e., parallel to the vertical flow direction or guide).

In a further advantageous embodiment of the invention, therefore, the float in the flow direction on a length of at least 5% of the length of the guide. In particular, the float in the flow direction has a length of at least 4mm.

In one embodiment of the invention, the float on a cylindrical portion.

In a further embodiment of the invention, the float has a recess, in particular a bore, introduced in an upper end face of the float, which is perpendicular to the flow direction. By means of the recess, on the one hand, the mass of the floating body can be reduced. This is advantageous, for example, to compensate for a large additional mass, which is caused by a required length of the float, which in turn is caused by the groove. On the other hand, such a recess impedes the adhesion of foreign bodies and / or air bubbles to the upper end face.

In an advantageous development, the roughness of the outer surface of the float is reduced by means of a surface finish, in particular by means of an electropolishing. Characterized an adhesion of foreign matter contained in the medium and / or air bubbles is minimized to the float so that they pass the float as simple as possible and can flow through the channel-shaped groove, and further can not adhere to upper and / or lower end faces of the float ,

The invention further relates to an analyzer for automated determination of a measured variable of a sample of a medium, in particular a fluid, with a variable area flowmeter according to the invention, which is designed to determine against the gravity directed flow of the medium in a vertically extending fluid line of the analyzer and / or monitor.

In one embodiment of the analyzer, the fluid line of the analyzer flows through the medium substantially continuously in a normal mode.

• 1: Eine perspektivische Ansicht einer Ausgestaltung eines Schwebekörpers eines erfindungsgemäßen Schwebekörper-Durchflussmessgeräts;
• 2a: Eine schematische Schnittansicht eines Analysegeräts eines erfindungsgemäßen Schwebekörper-Durchflussmessgeräts.
• 2b: Eine Schnittansicht einer Ausgestaltung eines erfindungsgemäßen Schwebekörper-Durchflussmessgeräts.

The invention will be explained in more detail with reference to the following, not to scale figures, wherein like reference numerals designate like features. If it requires clarity or otherwise makes sense, it will open already mentioned reference numerals omitted in subsequent figures. It shows:

• 1 : A perspective view of an embodiment of a floating body of a variable area flowmeter according to the invention;
• 2a : A schematic sectional view of an analyzer of a variable area flowmeter according to the invention.
• 2 B : A sectional view of an embodiment of a variable area flowmeter according to the invention.

1 shows a perspective view of an embodiment of a floating body 5 as in a variable area flowmeter according to the invention 1 , see. 2 B , is used. The outer surface 51 of the float 5 has a groove 7 with a V-shaped profile and an opening angle of about 90 °.

The float 5 has a cylindrical section 52 , and tapers conically at one end. This will cause the float 5 stabilized in the flow or can in the event that there is no flow, with its conically tapered end on one below the guide 3 (please refer 2 B ) arranged rest, such as a circular ring, rest.

The length LS of the float 5 is 9 mm, and the groove 7 has a maximum groove depth of 1.5 mm. At an upper end face 9 of the float 5 this has a bore introduced in the longitudinal direction of the float. This serves on the one hand, the mass ms of the float 5 on the other hand, this will cause air bubbles to adhere to the upper face 9 prevented. This is the outer surface 51 of the float 5 additionally treated with electropolishing, which reduces the roughness of the outer surface 51 of the float 51 is reduced.

The outer dashed line in 1 also indicates the inner wall 31 the leadership 3 on, cf. 2 B , The float 5 is dependent on the leadership 3 dimensioned such that the float 5 surrounding open space 6 the float 5 surrounding, between the outer surface 51 of the float 5 in the inner wall 31 the leadership 3 is present. This is in the cylindrical section 8th in a sectional plane transverse to the flow direction RD a gap surface SF, which is indicated by the dashed lines in FIG 1 is limited. The gap surface SF is greater than a predetermined gap surface minimum value SFM, or the gap surface SF and the mass Ms of the float 5 are matched to one another such that the quotient Ms / SF is smaller than a predetermined quotient maximum value QM. This fine adjustment can be done with the variable area flowmeter 1 , see. 2 B , even very small flow rates of less than 1 ml / h can be measured.

When measuring these very small flows flow in the medium 22 (please refer 2a , b) existing air bubbles through the channel-shaped and in the flow direction RD continuous groove 7 on the float 5 so that even with such inhomogeneous media 22 the very small flow rates can be reliably detected without any disturbing influence of the air bubbles. This is especially important in the event that the float flow meter 1 in an analyzer 20 is used, for example, as a limit switch, the presence of a minimum existing flow in a fluid line 2 to monitor. In this case, as described above, one would only be through air bubbles, but not through the flow at a wrong height in the guide 3 held float 5 Particularly problematic because the float incorrectly indicates too high a flow and thus possibly a wrong switching status.

Such an analyzer is shown in the schematic sectional view in FIG 2a shown a section of an analyzer 20 represents, with the II designated area the variable area flowmeter 1 shows. This variable area flowmeter 1 is in a sectional view in 2 B shown in detail, the features already described above may not be explained again.

The leadership 3 Float flowmeter 1 is designed as a bore, of course, but it is within the scope of the invention also possible a guide 3 to obtain with other methods known in the art.

In the lower part of the guide 3 this has a cylindrical section 8th on, which causes an initial stroke at low flow rates, with which the float 5 up to the conical section 4 is raised. The in flow direction RD continuous groove 7 is in this sectional view of the side of the float 5 visible, noticeable.

The height of the float 5 in the conical section 4 the leadership 3 represents a measure of the flow.

In the event that the leadership 3 is made of a transparent material, the height is, for example, by means of the guide 3 attached markings read.

Alternatively or additionally, with the in 2 B shown detection unit 21 the height of the float 5 in the conical section 4 and thus determines and / or monitors the flow. The detection unit 21 is for example designed as an electronic unit, which, based on a capacitive or optical measuring principle, the height of the float 5 in the conical section 4 detected.

For example, passing the floating body 5 detected at a certain height and thus the achievement of a predetermined flow; This is important in the event that the float flow meter 1 is used as a limit switch, with which a minimum vorzuliegender flow is monitored.

LIST OF REFERENCE NUMBERS

1

Variable Area Flowmeter

2

fluid line

3

guide

31

Inner wall of the guide

4

conical section of the guide

5, 5 '

float

51

Outer surface of the float

52

cylindrical portion of the float

6

free space

7

groove

8th

cylindrical section of the guide

9

upper face

10

recess

20

analyzer

21

detecting

22

medium

RD

Flow direction

Ms, Ms'

Mass of the hover body

SF

cleavage face

SFM

Cleavages minimum value

QM

Ratio maximum value

LS

Length of Schwebekörpes

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19624974 C1 [0002]
• DE 102012102256 A1 [0004]
• DE 10222822 A1 [0004]
• DE 10227032 A1 [0004]
• DE 102009029305 A1 [0004]

Claims (15)

Variable area flowmeter (1) for determining and / or monitoring an anti-gravity flow of a medium (22) in a vertically extending fluid conduit (2), comprising: - A guide (3) with a flow direction (RD) conically opening portion (4), and; - A floating body (5) arranged in the guide, which is configured such that between the inner wall (31) of the guide (3) and the outer surface (51) of the floating body (5) a free space (6) surrounding the floating body (5) is present, and that the outer surface (51) of the float (5) has a channel-shaped and in the flow direction (RD) continuous groove (7). Float flowmeter according to Claim 1 , wherein the groove (7) is dimensioned such that the mass (Ms) of the float between 1% to 20%, preferably between 2% to 10%, smaller than the mass (Ms') of an otherwise identically designed float (5 ') without groove (7). Float flowmeter according to Claim 1 or 2 wherein the guide (3) has a cylindrical portion (8) which is arranged in front of the conical portion (4) with respect to the flow direction (RD). Float flowmeter according to Claim 3 in that the float (5) is dimensioned with respect to the guide (3) in such a way that in the cylindrical portion (8) in a sectional plane transverse to the flow direction (RD) between the guide (3) and the floating body (5 ) is a gap area (SF) which is greater than a predetermined gap area minimum value (SFM), wherein the minimum gap area value (SFM) is 0.5 mm ² , preferably 2 mm ² . Float flowmeter according to Claim 3 or 4 in that the float (5) is dimensioned with respect to the guide (3) in such a way that in the cylindrical portion (8) in a sectional plane transverse to the flow direction (RD) between the guide (3) and the floating body (5 ) is a gap surface (SF), wherein the quotient of the mass (Ms) of the floating body (5) divided by the gap surface (SF) is smaller than a predetermined quotient maximum value (QM), and wherein the quotient maximum value (QM) in particular, 3 g / mm ^2, preferably 1.4 g / mm ^2. Float flowmeter according to at least one of the preceding claims, wherein the cylindrical portion (8) of the guide (3) is at least 10%, in particular at least 20% of the length of the guide (3). Float flowmeter according to at least one of the preceding claims, wherein the conical portion (4) of the guide (3) is at least 20%, in particular at least 30% of the length of the guide (3). Variable area flowmeter according to at least one of the preceding claims, wherein the channel-shaped groove (7) extends substantially parallel to the flow direction (RD). Float flowmeter according to at least one of the preceding claims, wherein the groove (7) has a substantially V-shaped or U-shaped profile. Float flowmeter according to at least one of the preceding claims, wherein in the flow direction (RD) of the float (5) has a length (LS) of at least 5% of the length of the guide (3), in particular at least 4mm. Float flowmeter according to at least one of the preceding claims, wherein the float (5) has a cylindrical portion (52). Variable area flowmeter according to at least one of the preceding claims, wherein the float (5) has a recess (10), in particular a bore, introduced in an upper end face (9) of the float (5) perpendicular to the flow direction (RD). Variable area flowmeter according to at least one of the preceding claims, wherein the roughness of the outer surface (51) of the float (5) by means of a surface finishing, in particular by means of an electropolishing, is reduced. Analysis device (20) for the automated determination of a measured quantity of a sample of a medium (22), in particular a fluid, with a variable area flowmeter (1) according to at least one of the preceding claims, which is designed to prevent a flow of the medium against gravity ( 22) in a vertically extending fluid line (2) of the analyzer (20) to determine and / or monitor. Analyzer (20) after Claim 14 , In a normal operation, the fluid line (2) of the analyzer (20) is flowed through substantially continuously by the medium (22).

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