DE102022103236A1 - Use of a device for combining gas bubbles in a fluid-gas mixture - Google Patents

Abstract

The present application relates to the use of a device (1) for combining gas bubbles (3) located in a fluid-gas mixture (2), the device (1) comprising a pipeline (4) for conducting the fluid-gas mixture ( 2). In order to simplify the separation of gas bubbles from a fluid-gas mixture compared to the prior art, it is proposed according to the invention that the pipeline (4) is designed in the form of a helical coiled tube (5).

Description

The present application relates to the use of a device for combining gas bubbles located in a fluid-gas mixture according to the preamble of claim 1. The present application also relates to a method for combining gas bubbles located in a fluid-gas mixture.

The device includes a pipeline for conducting the fluid-gas mixture. This can in particular be a pipeline with a circular cross section, which can be integrated into a hydraulic circuit, for example. The fluid-gas mixture can in particular be a mixture in which the fluid is formed by oil and the gas by air. The oil can in particular be a hydraulic oil.

Particularly in hydraulic circuits in which circulation of a fluid-gas mixture is driven by at least one pump, it is important that the mixture mentioned contain as few gas bubbles as possible, since these can be harmful to the respective pump. Accordingly, precautions are known to at least essentially separate the gas bubbles present in a fluid-gas mixture, so that the proportion of gas bubbles in the mixture is as small as possible.

Various approaches are known to achieve this. For example, it is customary to use the largest possible tank in which the respective fluid is kept. The dwell time of the fluid in the tank is increased as a result, so that gas bubbles contained in the fluid-gas mixture have enough time to rise and escape in this way. It is also known to design a tank with separate chambers, with a return line of a respective hydraulic circuit being connected to a first chamber and a supply line being connected to a second chamber. A transfer from the first chamber into the second chamber is only possible after a certain dwell time, so that it is ensured that the gas-fluid mixture sucked in at the feed line could at least essentially be freed from gas bubbles located therein. Finally, it is also conceivable to use screens, grids, filters and the like through which the fluid-gas mixture flows, with the unwanted gas bubbles being separated on the respective component.

The techniques described are disadvantageous from various aspects. In particular when used in agricultural working machines, it is fundamentally disadvantageous to be dependent on large volumes in a respective tank for the fluid in order to ensure a sufficient reduction in the gas bubbles in the fluid-gas mixture. The reason is that tanks of this type typically do not have the required structural volume and, in addition, in the interests of the lowest possible overall mass of the respective work machine, the dead weight caused by a large tank is undesirable. Separation by means of a separate filter or the like creates a high flow resistance and generally only partially separates the gas bubbles. In addition, filters are expensive.

As an alternative for such a form of separation of gas bubbles, reference is made to the German Offenlegungsschrift DE 21 05 926 A1 referred. This application has also set itself the task of removing gas bubbles from a fluid-gas mixture, the gas being formed from air and the fluid from oil. In order to achieve this, according to a disclosed embodiment, the fluid-gas mixture can be guided along a component that is inserted into a pipeline. Together with the pipeline, the component forms a helical flow section, with the pipeline forming the housing and a helical flow being generated within the pipeline by means of the component. This structure is complex and expensive. Strong turbulence and a flow that is as turbulent as possible should be achieved within the flow section. This leads to the technical effect that the comparatively heavy fluid is pressed radially outwards as a result of acting centrifugal forces and, correspondingly, conversely, individual small gas bubbles are guided radially inwards. As a result, a fluid-gas mixture remains in a radially inner area, in which the proportion of gas bubbles is greatly increased compared to a radially outer area of the fluid-gas mixture. In other words, the gas bubbles have been “collected” radially on the inside as a result of the guidance of the fluid-gas mixture along the helical flow section. In order to discharge the proportion of the fluid-gas mixture in which the now high concentration of gas bubbles is present, a vent is provided which removes the fluid-gas mixture lying radially on the inside from the associated pipeline. The gas bubbles are then separated from the fluid-gas mixture discharged via the pipeline.

The procedure described is comparatively complex, since a special component must be provided within the respective pipeline in order to provide the helical flow. Furthermore, a separate deduction is required to the fluid-gas mixture in the Draw off the area in which the concentration of the gas bubbles was deliberately increased from the pipeline.

The present application is therefore based on the object of simplifying the separation of gas bubbles from a fluid-gas mixture compared to the prior art.

The underlying object is achieved according to the invention by using the features of claim 1 . Advantageous refinements result from the associated subclaims.

The invention is based on the fundamental idea that a separation of gas bubbles is particularly easy when large-volume gas bubbles are involved. A comparatively high buoyancy acts on such gas bubbles, so that they rise rapidly to a surface of the fluid-gas mixture. The invention provides that a pipeline, which is designed in the form of a helical coiled tube, is used in order to combine gas bubbles located in the respective fluid-gas mixture. The invention is therefore based on the fundamental idea that instead of directly separating gas bubbles in the respective mixture, a simplification can be achieved by first combining a large number of small gas bubbles to form individual, large gas bubbles.

In order to achieve this, the use of a helical coiled tubing has proven to be particularly suitable. The fluid-gas mixture is conducted through the pipeline formed in this way, with the heavy fluid being moved radially outwards and vice versa, the lighter gas bubbles radially inward relative to the pipeline as a result of acting centrifugal forces and thus being separated. The individual gas bubbles can then be combined to form larger gas bubbles on a wall section of the respective pipeline that is located radially on the inside relative to a central axis of the coiled tubing. This has the particular advantage that larger gas bubbles of this type can be separated particularly easily in a tank. In particular, it is not necessary to provide longer dwell times for the fluid-gas mixture in a tank, since the now combined gas bubbles rise very quickly and therefore a short dwell time of the fluid-gas mixture in the tank is sufficient to ensure adequate degassing of the to ensure the mixture. In order to achieve a combination of individual gas bubbles to form large gas bubbles, it is particularly advantageous if the gas-fluid mixture flows as laminarly as possible through the coiled tubing.

Many advantages are achieved by means of the use according to the invention. On the one hand, the design of the device is particularly simple compared to the prior art, since instead of installing a separate component in a pipeline, only the respective pipeline as such is guided in a coil. All that is required for this is to shape the pipeline accordingly, while separate components or the like can be dispensed with. Furthermore, there is the particular advantage that no separate exhaust or the like is required to remove the undesired gas bubbles from the fluid-gas mixture. Instead, the gas-fluid mixture can be fed into a tank in the usual way, in which, due to the combination of small gas bubbles to form a few larger gas bubbles, the latter can now rise rapidly. In contrast to the prior art, no large-volume tank is required for this either, which would take up a significant amount of construction volume. The provision of separate components, such as grids, filters or the like, can be completely dispensed with.

In a particularly advantageous embodiment, the device is used in an agricultural working machine. This can in particular be a tractor, a combine harvester or a forage harvester. In particular, the device can be used in a hydraulic circuit of such a working machine.

Furthermore, the use is particularly advantageous when the gas of the fluid-gas mixture is air and the fluid is oil. The oil can in particular be a hydraulic oil. Hydraulic circuits are typically particularly susceptible to high concentrations of gas bubbles in the respective fluid-gas mixture. The risk of damage to the pumps used in each case has already been explained at the outset.

In a further advantageous embodiment, the device is used in a separate secondary circuit in which hydraulic pressure acts on the fluid-gas mixture as a result of the operation of at least one pump. In this case, the device can be arranged directly downstream of the pump. This has the technical effect that said mixture is actively routed through the secondary circuit. Additionally or alternatively, the use of the device described can be advantageous in a return line in which the fluid-gas mixture is conducted at least essentially without pressure. In terms of process technology, a cooler and a filter can be arranged upstream of the device. Because the flow rate of the fluid-gas mixture in a return line is typically lower than in a secondary circuit, it can also be advantageous if the pipeline has a larger diameter in a return line in the area of the helical coiled tubing, so that the flow rate of the fluid-gas mixture is not additionally impeded by the coiled tubing. This leads to higher absolute centrifugal forces acting on the gas-fluid mixture, which in turn promotes the desired collection and subsequent combination of gas bubbles radially on the inside of the pipeline.

In order to achieve the described effect of separating fluid and gas bubbles to the greatest possible extent, it is particularly advantageous if the coiled tubing has at least one winding, preferably a plurality of windings, more preferably a large number of windings. In particular, such an embodiment can be particularly advantageous in which the coiled tubing has at least five turns, preferably at least ten turns. A higher number of turns is usually associated with a longer flow distance that the fluid-gas mixture has to cover in the coiled tubing. This creates time for the gas bubbles to combine as comprehensively as possible along the coiled tubing.

Furthermore, the use of such a device is particularly advantageous if, taking into account the prevailing boundary conditions in the respective application situation, it is set up so that the gas-fluid mixture flows through the pipeline in the form of a laminar flow. In particular, it has been shown that, moving away from a turbulent vortex flow proposed by the prior art, the combination of individual gas bubbles in the helical coiled tube works more efficiently if the flow characteristics of the fluid-gas mixture are laminar. In particular, the individual small gas bubbles that collect on a radially inner wall section of the coiled tubing due to the principles described above are not swirled, which would make merging more difficult. In the calm of a laminar flow, on the other hand, the gas bubbles can combine particularly easily.

The underlying object is also achieved by means of a method having the features of claim 8. This method is intended to combine gas bubbles present in a fluid-gas mixture. For this purpose, the fluid-gas mixture is passed through a helical coiled tube, as a result of which centrifugal forces act on the fluid-gas mixture. As a result of these centrifugal forces, the fluid in the fluid-gas mixture is pressed radially outwards, as a result of which individual gas bubbles in the fluid-gas mixture collect radially inward relative to a central axis of the coiled tubing on a wall section of the respective pipeline and combine to form larger gas bubbles. This method can be carried out in a particularly simple manner by using a pipeline designed in the form of a helical coiled tube according to one of the configurations described above. The resulting advantages have already been explained above. In particular, by means of the method according to the invention, individual gas bubbles are combined particularly effectively to form larger gas bubbles, as a result of which they can be separated off in a particularly simple manner. Additional components, such as filters, or other elements that come into direct contact with the fluid-gas mixture can be dispensed with.

In an advantageous embodiment of the method according to the invention, the fluid-gas mixture is passed through the coiled tubing in such a way that an at least substantially laminar flow is established within the coiled tubing. The resulting advantages have already been explained above.

Furthermore, such an embodiment of the method can be particularly advantageous in which the fluid-gas mixture flows downstream of the coiled tubing into a tank in which the combined gas bubbles rise and are thereby separated from the fluid-gas mixture. Because the gas bubbles are now combined, the buoyancy of each individual gas bubble is greatly increased compared to gas bubbles that are particularly finely distributed in the fluid-gas mixture. This has the technical effect that even after the fluid/gas mixture has been in a tank for a comparatively short time, the gas bubbles can rise to a surface of the fluid/gas mixture and thereby escape from the fluid/gas mixture. A longer dwell time of the fluid-gas mixture in the respective tank is accordingly not necessary, at least for the purpose of separating the respective gas. Accordingly, there is no need to construct comparatively large-volume tanks, the purpose of which is to provide long residence times for the respective fluid-gas mixture.

Finally, such an embodiment of the method according to the invention is particularly advantageous in which the fluid-gas mixture is passed through the coiled tubing in such a way that a centrifugal force of at least 10 times the gravitational acceleration, preferably at least 15 times the gravitational acceleration, more preferably at least 20 times the acceleration due to gravity, acts on the fluid-gas mixture. With this procedure, the centrifugal forces acting on the fluid-gas mixture are particularly large Amount so that the separation of fluid and gas according to the manner described above is particularly effective. In order to "set" a desired centrifugal force in individual cases, it is particularly advantageous to set the design parameters of the pipeline depending on the prevailing boundary conditions. This relates in particular to a number of turns of the helical coiled tubing, a diameter of the pipeline and a radius of the coiled tubing.

• 1: Einen Querschnitt durch eine landwirtschaftliche Arbeitsmaschine in Form eines Mähdreschers,
• 2: Eine schematische Darstellung eines Hydraulikkreislaufs, in dem eine helixförmige Rohrwendel verwendet wird, um Gasblasen eines Fluid-Gas-Gemischs zu vereinen,
• 3: Eine schematische Darstellung eines weiteren Hydraulikkreislaufs und
• 4: Ein schematischer Querschnitt durch eine Rohrleitung einer helixförmigen Rohrwendel.

The invention is explained in more detail below using an exemplary embodiment which is illustrated in the figures. It shows:

• 1 : A cross section through an agricultural working machine in the form of a combine harvester,
• 2 : A schematic representation of a hydraulic circuit in which a helical coiled tubing is used to combine gas bubbles of a fluid-gas mixture,
• 3 : A schematic representation of another hydraulic circuit and
• 4 : A schematic cross section through a pipeline of a helical coiled tubing.

An embodiment in the 1 until 4 is shown deals with a device 1 for combining gas bubbles 3 located in a fluid-gas mixture 2. The device 1 is used here in an agricultural working machine 6, which is designed in the form of a self-propelled combine harvester. This is based on 1 recognizable. The working machine 1 comprises a cutting element 13, by means of which plants to be harvested can be cut off from a field. These are then fed by means of a conveyor element 14 to a threshing element 15, by means of which fruits are detached from the remaining plant remains. The fruits are separated from the plant residues by means of a downstream separating device 16 , the separated fruits being collected in a grain tank 17 .

The device 1 comprises a pipeline 4 through which the fluid-gas mixture 2 can be conducted or is conducted. The pipeline 4 is in the form of a helical coiled tubing 5, which is particularly based on the 2 and 3 results. As such, the helical coil tubing 5 comprises a plurality of individual coils winding in a radius about a central axis 10 of the coil tubing 5 . Using the example of 2 the device 1 is integrated into a hydraulic circuit 7 which is operatively connected to a tank 11 . The gas-fluid mixture 2 is held in the tank 11 so that it can be routed to a consumer via a supply line 19 for further use and can be routed back to the tank 11 via a return line 18 . In the example shown, the fluid is a hydraulic fluid in which gas in the form of air is undesirably dissolved. In order to protect pumps of a respective hydraulic circuit 7, it is necessary to separate at least a significant portion of the gas bubbles 3 contained in the fluid-gas mixture 2 from the same.

This takes place according to the invention by means of the inventive use of the pipeline 4 designed as a helical coiled tube 5. For this purpose, using the example of the use of the described device 1 in a secondary circuit 8, the fluid-gas mixture 2 is pumped by means of a pump 9 under a comparatively high pressure into the pipeline 4 pumped. Due to the helical design, in which the fluid-gas mixture 2 winds helically around the central axis 10 of the device 1, centrifugal forces act on the fluid-gas mixture 2. These cause the comparatively heavy fluid 22 to radially contact an outer wall section of the pipeline 4 is pressed in relation to the central axis 10, while gas bubbles 3 migrate radially inwards and collect on an inner wall area of the pipeline 4 and unite there to form larger gas bubbles 3.

This has the technical effect that the gas-fluid mixture is separated after flowing through the device 1 at least in such a way that the gas is dissolved in a few large gas bubbles 3 in the fluid 22 . The fluid-gas mixture 2 prepared in this way is routed back to the tank 11 in which the gas bubbles 3 created in this way rise particularly easily and can thus be separated from the fluid-gas mixture 2 .

In addition to using the device 1 in a secondary circuit 8, it can also be used in a return line 12, as is the case, for example, with reference to FIG 3 shown. In a hydraulic circuit 7 there, which is also operated by means of a pump 9, the device 1 is preceded by a filter 20 and a cooler 21. In order to protect them from damage, the fluid-gas mixture 2 can only be passed through the return line 12 with a low pressure. A combination of gas bubbles 3 according to the above principle by means of a pipeline 4 designed as a helical coiled tube 5 is nevertheless possible. It may be advantageous here to adapt the device 1 as required to the respective application, for example a cross-section of the pipeline 4 compared to an application in which a gas-fluid Mixture 2 is passed through the device 1 at high pressure, is increased in order to avoid inhibition of the flow rate of the fluid-gas mixture 2 in the pipeline 4.

In principle, it is of particular advantage if the device 1 is designed and constructed in such a way that an at least essentially laminar flow is established within the pipeline 4 in the course of its operation. Such is advantageous for the separation and subsequent combination of gas bubbles 3 from the fluid 22 of a respective fluid-gas mixture 2 .

Reference List

1

contraption

2

fluid-gas mixture

3

gas bubble

4

pipeline

5

coiled tubing

6

work machine

7

hydraulic circuit

8th

subgroup

9

pump

10

central axis

11

tank

12

return line

13

cutting organ

14

funding body

15

threshing organ

16

separator

17

grain tank

18

hydraulic return

19

hydraulic flow

20

filter

21

cooler

22

Fluid

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 2105926 A1 [0006]

Claims (11)

Use of a device (1) for combining gas bubbles (3) located in a fluid-gas mixture (2), the device (1) comprising a pipeline (4) for conducting the fluid-gas mixture (2), characterized that the pipeline (4) is designed in the form of a helical coiled tubing (5). use after claim 1 , characterized in that the device (1) is used in an agricultural working machine (6), in particular in a hydraulic circuit (7) of an agricultural working machine (6). Use according to one of the preceding claims, characterized in that the gas consists of air and the fluid consists of oil, in particular a hydraulic oil. Use according to one of the preceding claims, characterized in that the device (1) is used in a secondary circuit (8) in which hydraulic pressure acts on the fluid-gas mixture (2) as a result of the operation of at least one pump (9). , so that this is actively conducted in the secondary circuit (8). Use according to one of the preceding claims, characterized in that the device (1) is used in a return line (12) in which the fluid-gas mixture (2) is conducted at least essentially without pressure. Use according to one of the preceding claims, characterized in that the coiled tubing (5) has at least one winding, preferably a plurality of windings, more preferably a large number of windings. use after claim 6 , characterized in that the coiled tubing (5) has at least five turns, preferably at least ten turns. Method for combining gas bubbles (3) in a fluid-gas mixture (2), in which the fluid-gas mixture (2) is passed through a helical coiled tube (5), in which case, as a result of centrifugal forces acting in relation to a central axis (10th ) the coiled tubing (5) a fluid of the fluid-gas mixture (2) is pressed radially outwards, whereby individual gas bubbles (3) of the fluid-gas mixture (2) radially inward relative to the central axis (10) in a Collect the pipeline (4) of the coiled tubing (5) and combine to form larger gas bubbles (3). procedure after claim 8 , characterized in that the fluid-gas mixture (2) is passed through the coiled tubing (5) in such a way that an at least substantially laminar flow is established within the coiled tubing (5). Method according to one of the preceding claims, characterized in that the fluid-gas mixture (2) downstream of the coiled tubing (5) enters a tank (11) in which the combined gas bubbles (3) rise and thereby from the fluid-gas -Mixture (2) are deposited. Method according to one of the preceding claims, characterized in that the fluid-gas mixture (2) is passed through the coiled tubing (5) in such a way that a centrifugal force of at least 10 times the gravitational acceleration, preferably at least 15 times the gravitational acceleration, more preferably at least 20 times the gravitational acceleration, acts on the fluid-gas mixture (2).

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