Device for collecting particles contained in an aerosol, comprising electrometres to determine nanoparticle concentration and particle size

Patent metadata

Field	Value
Publication number	US-10675639-B2
Application number	US-201615744291-A
Country	US
Kind code	B2
Filing date	Jul 28, 2016
Priority date	Jul 28, 2015
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

The invention relates to a method and device for collecting nanoparticles which may be present in an aerosol. The invention consists of electrostatically collecting nanoparticles contained in an aerosol by a mechanism of particle charging by unipolar ion diffusion, followed by the application of a field without a corona effect, which makes it possible to deposit the particles in concentric rings on different parts of a single flat substrate oriented orthogonally to the aerosol circulation direction. The biggest particles are deposited towards the centre of the flat substrate and the finest particles towards the periphery of the flat substrate. The invention also relates to a method of operation and to the use of such a device for evaluating the exposure of workers or consumers to nanoparticles.

First claim

The invention claimed is:

1. A device for collecting nanoparticles likely to be present in an aerosol, comprising:
a conduit in the form of a hollow cylinder for rotating about a longitudinal axis (X), the conduit comprising an inlet orifice and an outlet orifice, between which the aerosol may circulate;
suction means for circulating the aerosol from the inlet orifice to the outlet orifice;
a unipolar ion diffusion charger, downstream of the inlet orifice, comprising an electrode in the form of a wire that extends along the axis (X) and is surrounded by an electrode in the form of a gate, the charger being adapted to charge the nanoparticles in the space separating the gate from a conducting portion of the internal wall of the conduit by diffusing unipolar ion through the gate;
a field electrode, downstream of the diffusion charger, which electrode is in the form of a circular plate that extends orthogonal to the axis (X), and at least one flat substrate, parallel to the field electrode, perforated in its central part with a through opening, and comprising various concentric rings around the through opening individually connected to at least one electrometer;
the potential difference applied between the field electrode and the substrate being adapted to generate an electric field without a corona effect in the space that separates them and thus, on the one hand, to allow particles bigger than nanoparticles to pass through the through opening and, on the other hand, to collect the nanoparticles previously charged by the diffusion charger by deposition onto a collection zone of the flat substrate defined by the various rings.

2. The collection device as claimed in claim 1 , further comprising a system adapted to allow the aerosol flow circulating in the space separating the gate from the internal wall of the conduit to be enveloped between two laminar flows of filtered air.

3. The collection device as claimed in claim 1 , further comprising, downstream of the through opening of the collection substrate, a filter adapted to retain the particles having passed through the through opening, the filter being able to be connected to an electrometer.

4. The collection device as claimed in claim 1 comprising, downstream of the through opening of the collection substrate, an element consisting in a disk supporting a tip connected to a high-voltage power supply for creating a corona discharge, so as to collect, on the lower face of the substrate, the particles having passed through the through opening, by means of an electric collection field imposed between the substrate and the disk.

5. The collection device as claimed in claim 1 , comprising, downstream of the through opening of the collection substrate, a trap in the form of a disk perforated with a blind hole interposed below the opening, so as to collect by inertial impaction, according to a given size range, part of the particles having passed through the through opening.

6. The collection device as claimed in claim 5 , wherein the blind hole comprises lips in the form of a tip, the disk being connected to a high-voltage power supply to create a corona discharge in the space between the lower face of the substrate and the lips of the blind hole so as to collect, according to a given size range, only part of the particles having passed through the through opening, preferably particles with dimensions between 0.1 and 4 μm.

7. The collection device as claimed in claim 5 , comprising an additional element, the disk being connected to a high-voltage power supply for creating a corona discharge in the space between the lower face or the upper face of the substrate and the additional element, so as to collect, according to a given size range, only part of the particles having passed through the through opening.

8. The collection device as claimed in claim 1 , the suction means being formed by a pump or a fan.

9. The collection device as claimed in claim 1 , the suction means being at least partly formed by plasma actuators.

10. The collection device as claimed in claim 1 , the field electrode being connected to a high-voltage power supply.

11. The collection device as claimed in claim 1 , the gate being connected to a low-voltage power supply.

12. The collection device as claimed in claim 1 , the flat substrate being connected to zero potential.

13. A method for operating a collection device as claimed in claim 1 , comprising a step of emitting an alarm in the event that a predetermined threshold value is exceeded that is measured using the one or more electrometer(s) connected to the concentric rings integrated in the collection substrate.

14. The collection device according to claim 7 , the additional element being a blade or a wire in the form of a tip.

Assignees

• Commissariat Energie Atomique

Inventors

• Clavaguera Simon
• Pourprix Michel
• Renot Quentin

Classifications

• B03C3/368

  by other than static mechanical means, e.g. internal ventilator or recycler · CPC title

• B03C3/49

  tubular · CPC title

• B03C3/12

  characterised by separation of ionising and collecting stations · CPC title

• B03C3/025 Primary

  Combinations of electrostatic separators, e.g. in parallel or in series, stacked separators or dry-wet separator combinations · CPC title

• B03C3/09

  characterised by presence of stationary flat electrodes arranged with their flat surfaces at right angles to the gas stream · CPC title