Electrostatic particle filtering

Patent metadata

Field	Value
Publication number	US-11413628-B2
Application number	US-201716465588-A
Country	US
Kind code	B2
Filing date	Dec 1, 2017
Priority date	Dec 1, 2016
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

An electrostatic air cleaning device comprises a particle charging section, a particle precipitation section, a current sensor for measuring an electric current flowing through electrode plates of the precipitation section and a relative humidity sensor. The voltage applied to the electrode plates and the air flow through the device are controlled in dependence on the measured current flowing through the electrode plates. In this way, control is provided to prevent excessive electric leakage currents inside the precipitation section, that may lead to a hazard, and to optimize the energy efficiency of the cleaning device in relation to its cleaning performance. The relative humidity information also enables diagnosis of the cause of the high leakage current and the status of the precipitation section concerning the amount of precipitated particles therein.

First claim

The invention claimed is:

1. An electrostatic air cleaning device, comprising:
a particle charging section;
a particle precipitation section, comprising parallel electrode plates;
a source of electric potential for applying a voltage between adjacent electrode plates in the particle precipitation section;
a current sensor for measuring an electric current flowing through the electrode plates;
a relative humidity sensor for sensing relative humidity of air;
a flow controller; and
a device controller,
wherein the device controller is adapted to control the source of electric potential and the flow controller in dependence on the measured electric current flowing through the electrode plates, and wherein the device controller is adapted to implement:
a first, normal, operation mode when the measured electric current flowing through the electrode plates is below a current threshold;
a second operation mode when the measured electric current flowing through the electrode plates is above the current threshold and the source of electric potential is controlled to reduce the electric current, wherein the flow controller is controlled to achieve a desired filtration efficiency, and wherein the measured electric current being above the current threshold is caused by a high relative humidity; and
a third operation mode when the measured electric current flowing through the electrode plates is above the current threshold and the source of electric potential is controlled to reduce the electric current, wherein the flow controller is controlled to achieve the desired filtration efficiency, wherein the measured electric current being above the current threshold is caused by a level of particle deposition in the particle precipitation section, and wherein, in the third operation mode, the device controller is adapted to provide output information as an output signal indicating that cleaning or replacement of the particle precipitation section is required.

2. The electrostatic air cleaning device as claimed in claim 1 , wherein the device controller is adapted to implement the first operation mode by applying a maximum electric potential between the adjacent electrode plates, and wherein the flow controller is adapted to implement a flow rate as selected by a user of the electrostatic air cleaning device.

3. The electrostatic air cleaning device as claimed in claim 1 , wherein the device controller is adapted to implement the second operation mode when the sensed relative humidity exceeds a humidity threshold and to reduce the electric potential applied between the adjacent electrode plates until the measured electric current flowing through the electrode plates reduces to the current threshold, and wherein the flow controller is adapted to implement a flow rate reduction until the desired filtration efficiency reaches an efficiency threshold.

4. The electrostatic air cleaning device as claimed in claim 1 , wherein the device controller is adapted to implement the third operation mode when the sensed relative humidity is below a humidity threshold and to reduce the electric potential applied between the adjacent electrode plates until the measured electric current flowing through the electrode plates reduces to the current threshold, and wherein the flow controller is adapted to implement a flow rate reduction until the desired filtration efficiency reaches an efficiency threshold.

5. The electrostatic air cleaning device as claimed in claim 3 , wherein the efficiency threshold comprises a fractional filtration efficiency for a particular particle size.

6. The electrostatic air cleaning device as claimed in claim 5 , wherein the particular particle size is 200 nm particle diameter and the efficiency threshold is 0.9.

7. The electrostatic air cleaning device as claimed in claim 1 , wherein the flow controller is a fan.

8. An electrostatic air cleaning method, comprising:
charging airborne particles in an air flow using a charging section;
filtering the air flow using a particle precipitation section which comprises parallel electrode plates having a voltage between adjacent electrode plates;
measuring an electric current flowing through the electrode plates;
sensing a relative humidity; and
controlling the voltage between the adjacent electrode plates and controlling the air flow in dependence on the measured electric current flowing through the electrode plates, wherein a device controller, comprised in an electrostatic air cleaning device, implements:
a first, normal, operation mode when the measured electric current flowing through the electrode plates is below a current threshold;
a second operation mode when the measured electric current flowing through the electrode plates is above the current threshold, and a source of electric potential is controlled to reduce the electric current, wherein a flow controller, comprised in the electrostatic air cleaning device, is controlled to achieve a desired filtration efficiency, and wherein the measured electric current being above the current threshold is caused by a high relative humidity; and
a third operation mode when the measured electric current flowing through the electrode plates is above the current threshold and the source of electric potential is controlled to reduce the electric current, wherein the flow controller is controlled to achieve the desired filtration efficiency, wherein the measured electric current being above the current threshold is caused by a level of particle deposition in the particle precipitation section, and wherein, in the third operation mode, the device controller provides output information as an output signal indicating that cleaning or replacement of the particle precipitation section is required.

9. The electrostatic air cleaning method as claimed in claim 8 , comprising implementing the first operation mode by applying a maximum electric potential between the adjacent electrode plates, and implementing a flow rate as selected by a user of the electrostatic air cleaning device.

10. The electrostatic air cleaning method as claimed in claim 8 , comprising implementing the second operation mode when the sensed relative humidity exceeds a humidity threshold and by reducing the electric potential between the adjacent electrode plates until the measured electric current flowing through the electrode plates reduces to the current threshold, and implementing a flow rate reduction until the desired filtration efficiency reaches an efficiency threshold.

11. The electrostatic air cleaning method as claimed in claim 8 , comprising implementing the third operation mode when the sensed relative humidity is below a humidity threshold and by reducing the electric potential applied between the adjacent electrode plates until the measured electric current flowing through the electrode plates reduces to the current threshold, and implementing a flow rate reduction until the desired filtration efficiency reaches an efficiency threshold.

12. The electrostatic air cleaning method as claimed in claim 10 , wherein the efficiency threshold comprises a fractional filtration efficiency for a particular particle size, for example, 200 nm particle diameter, and wherein the efficiency threshold is 0.9.

13. A non-transitory computer readable recording medium storing a computer program comprising computer program code means which is adapted, when said computer program is run on a computer, to implement the electrostatic air cleaning method of claim 8 .

Assignees

• Koninklijke Philips Nv

Inventors

• Marra Johannes
• Koerber Achim Gerhard Rolf
• Ronda Cornelis Reinder

Classifications

• B03C3/12 Primary

  characterised by separation of ionising and collecting stations · CPC title

• B03C3/68 Primary

  Control systems therefor {(electricity supply or control systems for cleaning the electrodes B03C3/746, B03C3/763)} · CPC title

• B03C3/08

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

• B03C2201/32

  Checking the quality of the result or the well-functioning of the device · CPC title

• B03C3/47

  flat, e.g. plates, discs, gratings · CPC title