SYSTEM FOR SUSPENDING SUBMICRON PARTICLES IN A LIQUID, AND ASSOCIATED METHOD
The closed-loop circulation system with ultrasound emission addresses the challenge of achieving uniform suspension of submicron particles by breaking down clusters and promoting dispersion, resulting in improved suspension quality and handling efficiency.
Patent Information
- Application Number
- FR2013051081
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2013-02-08
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2033-02-08
AI Technical Summary
Existing methods for dispersing submicron particles in liquids face challenges in achieving uniform suspension, particularly when dealing with dry powders, as they often result in particle clustering and inefficient mixing.
A closed-loop circulation system is employed, where a liquid containing submicron particles is circulated through a container with ultrasound emission means, ensuring optimal homogenization and dispersion of particles by breaking down clusters and promoting steric or electrostatic dispersion.
This method effectively improves the quality of the particle suspension by reducing clusters and ensuring uniform distribution, making it easier to handle and transport the particle-laden liquid.
Smart Images
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Abstract
Description
if the particles contained in space 9 are in the form of dry powder, (i.e. the container initially includes the submicron particles but does not initially include liquid), then the liquid is injected into the container through the connector 14, to mix the liquid with the particles. For this, the connector 14 is connected to a source of liquid. It is possible to add additives to the container through the connector 14. liquid so as to promote the dispersion of the particles with respect to each other in the liquid, the additives used depending on the liquid used and the nature of the particles and in particular their surface chemistry. In particular, dispersants can be used to ensure dispersion by steric or electrostatic effect, or even by both effects of the particles. if the particles are already in suspension, it is possible to supplement by adding the same or different liquid or not inject liquid through connection 14. At this stage, the space 9 therefore comprises a mixture 16 of submicron particles 17 and liquid. The liquid is a solvent or water with possibly an additive for the submicron particles, for example demineralized water or any type of compatible solvent such as isopropyl alcohol. More precisely, the internal space 9 of the container 8 comprises a liquid phase 16 comprising the liquid and the submicron particles 17 in suspension, and a gaseous phase 18. Afterwards : - the outlet connection 10 of the container 8 is connected to the pumping connection 3 of the circulation device 2, so that the outlet connection 10 opens, on the side of the space 9, onto the mixture 16 and not onto the gas phase 18, that is to say so that any liquid which leaves the space 9 via the outlet connection 10 passes directly from the mixture 16 to the outlet connection 10 without passing through the gas phase 18; and - the inlet connection 11 of the container 8 is connected to the reinjection connection 4 of the circulation device 2, so that the inlet connection 11 opens, on the side of the space 9, onto the gas phase 18 and not onto the mixture 16, that is to say so that any liquid which would enter the space 9 via the inlet connection 11 arrives in the gas phase 18 and only then falls into the mixture 16 after having passed through the gas phase 18. Then, this liquid 16 comprising the submicron particles 17 in suspension is circulated in a closed loop along a path successively comprising the internal space 9, the outlet connection 10, the pumping connection 3, pump 5, passage 6 provided with means 7 for emitting ultrasound, reinjection connection 4, and inlet connection 11 (then again the internal space 9, etc.) preferably directly from one to the other. The circulation and flow of liquid in a closed loop allows optimal homogenization of the suspension by avoiding any dead volume of fluid which would not be subjected to ultrasound. Furthermore, the circulation of fluid allows a simple implementation of the invention, notably less complicated or laborious than a conveyance of dry powders via a conduit and a diffuser. During this circulation, the pump is active so as to activate this circulation of liquid in a first direction. During this circulation, the emission means 7 emit ultrasound. The liquid 16 comprising the particles 17 and passing through the passage 6 are subjected to these ultrasounds which disassemble clusters of particles 17 stuck together. Thus, the quality of the suspension of the particles 17 in the liquid is improved, by reducing the number of clusters of particles. During circulation, the internal space 9 of the container 8 comprises only the liquid phase 16 comprising the liquid and the submicron particles 17 in suspension, and the gas phase 18 comprising a neutral gas (among helium, neon, argon, krypton, xenon, and radon) but not comprising oxygen or air. It is noted that during circulation, the mixture 16 of liquid and particles 17 suspended in this liquid is the same in the container 8 as that passing through the pump 5 and through the passage 6. No particles or molecules are filtered (and the system 1 does not include means for filtering) between the container 8 (more precisely its space 9) and the pump 5 or the passage 6. The system 1 includes a shut-off valve 19 for cutting off the circulation. The valve 19 is preferably located between the connector 10 and the pump 5 along the path of the circulating fluid. Then the circulation of the liquid is stopped. The duration of the circulation depends on the quality of the desired suspension. This duration is typically one hour for 300 liters of particle suspension. silicon carbide with an average diameter of 35 nm and for a pump with a flow rate of 6 m3 / hour and for ultrasound emission means with a typical power of 1000W and an ultrasound frequency of 25 to 40 kilohertz. Then, the pump 5 is emptied. During this emptying, the pump 5 is active so as to activate a circulation of fluid (comprising the mixture 16 and / or the gas phase 18) in a second direction opposite to the first direction: this fluid (mixture 16 and / or gas phase 18) is circulated in a closed loop along a path successively comprising the internal space 9, the inlet connector 11, the reinjection connector 4, the passage 6 provided with means 7 for emitting ultrasound, the pump 5, the pumping connector 3, and the outlet connector 10, (then again the internal space 9, etc.). During this emptying, the emission means 7 do not emit ultrasound. During emptying, the internal space 9 of the container 8 still only comprises the liquid phase 16 comprising the liquid and the submicron particles 17 in suspension, and the gas phase 18. Then, after circulation in the first direction and emptying: disconnect the outlet connection 10 from the pumping connection 3, and disconnect the inlet connection 11 from the reinjection connection 4 so as to separate the container 8 from the circulation device 2 while retaining the liquid comprising the suspended particles inside the internal space 9. Disconnection of the fittings is preferably done using quick couplings, which prevents outside air from being introduced into the system and maintains a controlled atmosphere. Then, optionally, the container is transported so as to move it away from the device 2, for example to take it (for example by truck) to a site or factory of a manufacturer using submicron particles within an industrial process. Then, the discharge valve 12 is opened by coupling with an “active” valve and the liquid 16 comprising the suspended submicron particles is discharged through the discharge valve. The circulation device 2 further comprises a control panel (not shown, typically provided with buttons, levers, etc.) arranged for: order the start of pump 5, choose the direction of circulation (first direction of circulation for the emission of ultrasound or second direction of circulation for emptying) actuated by pump 5, order the start-up of the means 7 for emitting ultrasounds, adjust the frequency of the ultrasound emitted by the means 7. Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. For example, the order of the steps of the method according to the invention can be modified. Of course, the various features, forms and variant embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.
Claims
R.ECLAIMS 1. Method for suspending submicron particles in a liquid, implemented in a system for suspending submicron particles in a liquid which comprises: - a circulation device (2) comprising a liquid pumping connection (3) and a liquid reinjection connection (4), said device being arranged to circulate a liquid from the pumping connection (3) to the reinjection connection (4) via a pump (5) and a liquid passage (6) provided with means (7) for emitting ultrasound in this passage (6), - a container (8) of submicron particles, comprising: • an internal space (9) for storing submicron particles, • an outlet connection (10) arranged to be open to allow passage of liquid therethrough from the internal space (9) to the outside of the container (8) when connected to the complementary liquid pumping connection (3). • an inlet connection (11) arranged to be open to allow passage of liquid therethrough from outside the container to the internal space (9) when connected to the complementary reinjection connection (4). Said method comprising the following steps: the container (8) is provided detached from the circulation device (2), then the outlet connection (10) of the container is connected to the pumping connection (3) of the circulation device, and the inlet connection (11) of the container is connected to the reinjection connection (4) of the circulation device, then a liquid comprising submicron particles suspended in a closed loop is circulated along one path successively comprising the internal space (9), the outlet connection (10), the pumping connection (3), the assembly comprising the pump (5) and the passage (6) provided with means (7) for emitting ultrasound, the reinjection connection (4), and the inlet connection (11), the emission means (7) emitting ultrasound during this circulation. said method being characterized in that the container initially comprises the submicron particles but does not initially comprise liquid, and in that the liquid is injected into the container before the circulation of the liquid.
2. Method according to claim 1, characterized in that during circulation, the internal space (9) of the container comprises only a liquid phase comprising the liquid and the submicron particles in suspension, and a gaseous phase.
3. Method according to any one of the preceding claims, characterized in that the container (8) further comprises a discharge valve (12) for the submicron particles having an open state allowing the submicron particles to pass through it between the internal space and the exterior of the container and a closed state preventing the submicron particles from entering or leaving the internal space through it.
4. Method according to claim 3, characterized in that the unloading valve is a valve of a double valve mechanism, said unloading valve being equipped with locking means arranged to lock the unloading valve in its closed state and prevent its opening when this unloading valve is not connected to another valve of a double valve mechanism, complementary to the unloading valve and provided with specific unlocking means.
5. Method according to any one of claims 3 to 4, characterized in that the circulation of the liquid is stopped then the discharge valve is opened and the liquid comprising the suspended submicron particles is discharged through the discharge valve.
6. Method according to claim 5, characterized in that the steps of opening the unloading valve and unloading the liquid only take place after having: disconnected the outlet connection (10) from the pumping connection (3), and disconnected the inlet connection (11) from the reinjection connection (4).
7. Method according to any one of claims 1 to 6, characterized in that, after circulation, one: disconnects the outlet connection (10) from the pumping connection 3, and disconnects the inlet connection (11) from the reinjection connection 4 so as to separate the container (8) from the circulation device (2) while retaining the liquid comprising the suspended particles inside the internal space (9).
8. Method according to any one of the preceding claims, characterized in that the pump (5) is a peristaltic pump.