DEVICE AND METHOD FOR LOADING A LIQUID WITH A GAS

Abstract

A device for loading an in particular higher-viscosity liquid, such as a silicon resin, for example, with air or another gas. The device has a pressure vessel receiving the liquid and the gas, in which pressure vessel an agitator, having a drive shaft set through the pressure vessel at least in part, is arranged. In order to enable the particularly fast and homogeneous intermixing of the liquid and gas, the drive shaft is arranged in a conveying pipe and drives a conveying organ, in particular a screw conveyor, which transports the liquid through the conveying pipe to at least one outlet, and there is an running-off surface underneath the outlet from the conveying pipe for the liquid flowing out of the outlet. Upon actuation of the agitator, the liquid is thus not only well intermixed together with the air already received therein, but at the same time conveyed through the conveying pipe to the running-off surface, on which it can discharge in a thin layer and has a particularly large exchange area with the gas as a result.

Claims

1-17. (canceled)

18. A device for loading an in particular higher-viscosity liquid with a gas, in particular with air, said device comprising: a pressure vessel receiving an associated liquid and an associated gas, an agitator being arranged in said pressure vessel, said agitator having a drive shaft vertically passing through the pressure vessel at least in part, the drive shaft is arranged in a conveying pipe and drives a conveying organ, which transports the associated liquid through the conveying pipe to at least one outlet and there is a running-off surface below the outlet from the conveying pipe for the associated liquid flowing out of the outlet.

19. The device according to claim 18, wherein the conveying organ is formed by a screw conveyor arranged in the conveying pipe being torque-proven coupled to the drive shaft.

20. The device according to claim 19, wherein the screw conveyor slightly protrudes from a lower end of the conveying pipe.

21. The device according to claim 18, wherein the running-off surface is formed by a conical or a frusto-conical surface being arranged around the conveying pipe.

22. The device according to claim 18, wherein an angle of inclination of the running-off surface is adjustable between a minimum value and a maximum value.

23. The device according to claim 22, wherein the angle of inclination of the running-off surface is infinitely adjustable between the minimum value and the maximum value.

24. The device according to claim 18, wherein the pressure vessel has at least one liquid inlet arranged above the running-off surface.

25. The device according to claim 18, further including at least one pressurised gas connection.

26. The device according to claim 25, wherein the at least one pressurised gas connection includes a pressurised gas connection that leads into the pressure vessel above a liquid level.

27. The device according to claim 25, wherein the at least one pressurised gas connection includes a pressurised gas connection that leads into the pressure vessel below a liquid level.

28. The device according to claim 27, wherein the at least one pressurised gas connection comprises a gas loading ring having a plurality of gas outlets arranged at a base of the vessel.

29. The device according to claim 18, further including a liquid discharge line being connected to the pressure vessel below a liquid level and a recirculation line being connectable, on the one hand, to the liquid discharge line and, on the other hand, to at least one liquid inlet.

30. The device according to claim 29, further including a gas loading measuring device being connected to a measuring point at least one of below the liquid level and in the liquid discharge line.

31. The device according to claim 18, wherein at least one overflow opening is arranged in the running-off surface.

32. The device according to claim 31, wherein the at least one overflow opening is closed off from downward flows from above by a valve member.

33. The device according to claim 32, wherein the valve member includes a valve plate.

34. The device according to claim 18, wherein a vertical guide surface is connected to the lower edge of the running-off surface.

35. The device according to claim 34, wherein the vertical guide surface is at least one of cylindrical and extends at least to a level of a liquid level.

36. A method for loading an in particular higher-viscosity liquid with a gas, in particular with air, wherein the liquid received by a pressure vessel is agitated by means of an agitator and conveyed inside the vessel through a conveying pipe to a level above the liquid level and conveyed through an outlet onto a running-off surface, on which the liquid discharges in a thin layer and at the same time is loaded with the pressurised gas located above the liquid level.

37. The method according to claim 36, wherein at least one of the pressure level inside the vessel, the amount conveyed through the conveying pipe per unit of time and the inclination of the running-off surface are adjustable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which form a part hereof and wherein:

[0020] FIG. 1 a vertical section of an embodiment of the device according to the invention; and

[0021] FIG. 2 a modified form of the device according to the invention shown in a simplified and schematic manner.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0022] Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting the same, reference sign 10 designates a device in its entirety used to load a higher-viscosity liquid 11, for example a silicone material used to produce a foam gasket, with air under superatmospheric pressure. When using such sealing material, the loading with air has a considerable effect on the subsequent quality of the foam gasket, in particular its surfaces and their pore structure. In general terms, it is intended to load the liquid, in other words the raw sealing material, with air until reaching the saturation limit, without any free air bubbles being present in the liquid. The device 10 according to the invention achieves fast and even dissolution of the air in the liquid, resulting in excellent foam quality when processing the material further at a later stage.

[0023] The device 10 has a pressure vessel 12 receiving the liquid 11, having a pressurised air connection 14 arranged on its cover 13. An agitator 15 is provided inside the vessel, having a drive shaft 16 vertically passing through the pressure vessel 12 being rotatably mounted at the centre of the vessel cover 13. The end of the shaft protruding upwardly from the vessel cover 13 is coupled—if need be, with interposition of a transmission—to a drive motor, which is schematically shown in FIG. 2 and designated with number 17.

[0024] At its lower end, the drive shaft 16 of the agitator 15 supports a mixer 18, which is fully immersed in the liquid 11. A conveying organ in the form of a screw conveyor 19 is coupled to the shaft 16 in a non-rotatable manner above the mixer 18 on the drive shaft 16. The drive shaft 16 and the screw conveyor 19 arranged thereon are contained in a conveying pipe 20 vertically passing through the pressure vessel and extending until slightly above the lower end of the screw conveyor. At the upper end of the conveying pipe 20, just below the bearing for the drive shaft 16, it is fitted with a plurality of drains 21 forming an outlet 22 for liquid 11, which is transported upwardly from below by the screw conveyor through the conveying pipe 20 when rotating the drive shaft.

[0025] On the outside of the conveying pipe 20 below the outlet 22, a conically inclined rotary discharge plate 23 is arranged having an adjoining guide cylinder 24 at its outer and lower edge that extends downwards in a parallel way in relation to the axis of the drive shaft 16. On its upper surface, the discharge plate 23 forms a running-off surface 25 for the liquid 11, which drains from the drains 21 and thus reaches the discharge plate 23, where it spreads in a thin layer on the upper running-off surface 25, the thickness of said layer depending, on the one hand, on the viscosity of the material and, on the other hand, the inclination of the upper frusto-conical surface of the discharge plate 23. The liquid flows over the lower edge of the running-off surface 25 and subsequently further along the outer cylindrical guide surface 26 of the guide cylinders 24 back into the liquid reservoir located below in the pressure vessel 12 and being intermixed by the mixer 18.

[0026] By means of the pressurised air connection 14 provided on the cover 13 of the pressure vessel 12, pressurised air can be introduced into the pressure vessel 12 and the desired level of pressure in the vessel 12 can be adjusted. In the embodiment shown in FIG. 1, the pressurised air connection 14 in the vessel cover 13 above the liquid level 28 is the only connection through which the gas to be dissolved in the liquid 11 is introduced into the vessel 12. In contrast, in the embodiment according to FIG. 2, an additional pressurised gas connection 29 is located below the liquid level 28 in the form of a gas loading ring 30 arranged down in the vessel below the mixer 18, said gas loading ring 30 having a plurality of gas outlets 31 through which the pressurised air can be directly introduced into the liquid 11 in the form of air bubbles. In this embodiment, the upper air connection 14 primarily serves as a regulating or controlling connection to maintain the pressure in the pressure vessel 12 at the desired level.

[0027] A liquid discharge line 33 is connected to the vessel base 32 of the pressure vessel 12, through which the material loaded with gas can be discharged from the vessel by means of a conveying pump 34. A gas loading measuring device 36 connected to a measuring point 35 before the conveying pump 34 determines the degree at which the liquid 11 is saturated with air, wherein this measurement can be used to adjust the adjustable parameters of the device such as the pressure in the vessel 12, the speed of the mixer 18 and the like, which is indicated here by the data line 37. A recirculation line 38 is connected to the discharge line 33 after the conveying pump 34 via a three-way valve, which can also receive an actuating signal from the gas load measuring device, for example when the detected degree of saturation has not (yet) reached the required level and the material must therefore be circulated back into the pressure vessel 12 to continue to be loaded with air. The recirculation line 38 leads into a liquid inlet 39, through which unprocessed liquid, i.e. liquid not having been loaded with gas, can be introduced into the pressure vessel 12.

[0028] By means of the device 10 depicted and described here, the gas, in particular air, can be particularly finely spread and dissolved in the liquid 11, for example a viscous silicone material, after only a short processing period. The mixer 18 of the agitator 15 ensures homogenisation of the material, which is pumped upwardly inside the conveying pipe above the liquid level 28 by means of the conveyor screw 19, 20, where it reaches the inclined running-off surface 25, on which it discharges back down in a thin layer. There is a large exchange area between the liquid and the pressurised gas located above the liquid level, through which the pressurised air can be dissolved in the liquid 11 and through which, on the other hand, air bubbles having formed due to a local over-concentration can outgas from the liquid in a particularly fast manner. The thin layer gassing and degassing in the pressure vessel 12 results in particularly fast homogenisation and dissolution of the gas in the liquid, which can then be discharged for further processing through the discharge line.

[0029] In order to prevent a gas bubble from forming below the discharge plate 23 inside the guide cylinder 24 when the liquid level 28 rises above the lower edge of the guide cylinder 24, overflow openings 40 are provided in the upper, conical discharge plate 23, which ensure an equalisation of pressure and thus an equally high liquid level in and outside the guide cylinder. In order to be able to prevent liquid flowing over the running-off surface 25 from passing through the overflow openings 40 from above, the overflow openings 40 can be closed off against liquid passing through downwardly from above by means of valve plates or other suitable valve members being elastically or flexibly attached to the upper surface of the discharge plate.

[0030] The invention is not limited to the exemplary embodiment shown, instead different changes and additions are possible, without departing from the scope of the invention. As an example, it is also possible for the inclination of the running-off surface 25 to be variable in order to change the flow velocity and the layer thickness of the liquid material flowing over the running-off surface 25. The device can be used to load a liquid with gas in batches; however, it is also possible to operate it in a continuous manner, introducing unloaded liquid and pressurised gas into the pressure vessel in equal measures, wherein the material already loaded with gas is discharged at the lower end of the vessel. The device is in particular suitable for processing silicone raw materials to produce silicone foam gaskets; however, it is also suitable for other materials, such as polyurethane resin and the like.

[0031] Further, while considerable emphasis has been placed on the preferred embodiments of the invention illustrated and described herein, it will be appreciated that other embodiments, and equivalences thereof, can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. Furthermore, the embodiments described above can be combined to form yet other embodiments of the invention of this application. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.