US3718029A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic mass per unit volume dust monitor
Assignee: GOURDINE SYST Inc
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Filing: 1971-01-25
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Granted: 1973-02-27
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Expires: 1991-01-25
Abstract
Abstract Electrogasdynamic methods and apparatus for measuring the mass of particulate matter entrained in a gaseous flow per unit volume of such flow are disclosed. The gaseous flow is passed down a bounded flow path and the entrained particles are exposed to and charged by a corona discharge. The charged entrained particles are carried downstream to a collection section where the particles are repelled by a charged deposition electrode and driven toward a grounded electrode. A portion of the charged particles are collected on a dielectric surface positioned in front of the grounded electrode. The accumulated charge on the dielectric surface is then measured by an induction electrode and an electrometer to show the particle mass per unit volume of the flow.
Inventors
- 👤 M Gourdine
- 👤 S Law
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:11
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/60
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
123 words
A method for determining the mass per unit volume of particles entrained in an ionizable gas, comprising the steps of flowing the gas through a bounded flow path; charging the particles to a given electrical polarity by means of a first corona discharge field at an upstream portion of the flow path; exposing the charged particles to a deposition electrical field at a downstream portion of the flow path, the deposition electrode of said field having the same polarity as the polarity of the charged particles; driving the charged particles toward the ground electrode of said field; depositing a portion of said charged particles on a dielectric surface positioned in said field, and determining by induction the accumulated charge on the dielectric surface.
Claim 2
Independent Claim
123 words
A method for determining the mass per unit volume of particles entrained in an ionizable gas, comprising the steps of flowing the gas through a bounded flow path; charging the particles to a given electrical polarity by means of a first corona discharge field at an upstream portion of the flow path; exposing the charged particles to a deposition electrical field at a downstream portion of the flow path, the deposition electrode of said field having the same polarity as the polarity of the charged particles; driving the charged particles toward the ground electrode of said field; depositing a portion of said charged particles on a dielectric surface positioned in said field, and determining by induction the accumulated charge on the dielectric surface.
Claim 3
Dependent Claim
21 words
A method in accordance with claim 1 wherein the first corona discharge field is established by a constant current power supply.
Claim 4
Dependent Claim
31 words
A method in accordance with claim 1 comprising the additional step of discharging the particles by means of a second corona discharge field positioned upstream of said first corona discharge field.
Claim 5
Dependent Claim
31 words
A method in accordance with claim 1 comprising the additional step of discharging the charged particles by means of a third corona discharge field positioned downstream of said deposition electric field.
Claim 6
Dependent Claim
35 words
A method in accordance with claim 1 comprising the additional step of separating out from the gas substantially all particles above a certain size, the separation taking place upstream of said first corona discharge field.
Claim 7
Dependent Claim
56 words
A method in accordance with claim 1 wherein the accumulated charge on the dielectric surface is determined by measurement by an induction electrode and the measurement of the accumulated charge is linearly related to the mass of the particulate matter per unit volume of the gas and is independent of the size of the particulate matter.
Claim 8
Dependent Claim
106 words
A method in accordance with claim 1 wherein the maximum voltage V permissible for said deposition electrical field is given by the relation V vg eta da2/2 epsilon oEofLa where vg is the velocity of the gas in the bounded flow path, eta is the viscosity of the gas, da is the distance from the deposition electrode To the dielectric surface, epsilon o is the permittivity of the gas, Eo is the first corona charging field, f is the fraction of saturation charge attained on the particulate matter, L is the length of the dielectric surface, and a is the average radius of the particulate matter.
Claim 9
Independent Claim
279 words
A method for determining the mass per unit volume of particles entrained in an ionizable gas, comprising the steps of flowing the gas through a bounded flow path; charging the particles to a given electrical polarity by means of a first corona discharge at an upstream portion of the flow path; exposing the charged particles to a deposition electrical field at a downstream portion of the flow path, the deposition electrode of said field having the same polarity as the polarity of the charged particles; driving the charged particles toward the ground electrode of said field; depositing a portion of said charged particles on a dielectric surface positioned in said field, and determining by induction the accumulated surface charge density on the dielectric surface, the surface charge density Rho s being determined as a function of time by the equation Rho s ( epsilon mV/dm) (1-e t/ ) for measurement times of t << Tau , where epsilon m is the permittivity of the dielectric surface, V is the voltage of the deposition electrical field, dm is the thickness of the dielectric surface, t is the time, and Tau is the dielectric surface-charging time constant given by the relation where epsilon a is the permittivity of the air, da is the distance between the deposition field electrode and the dielectric surface, epsilon o is the permittivity of the gas, Eo is the first corona charging field, f is the fraction of saturation charge attained on the particulate matter, eta is the viscosity of the gas, delta is the bulk density of the particulate matter, and M is the mass of the particulate matter per unit volume of the gas.
Claim 10
Independent Claim
279 words
A method for determining the mass per unit volume of particles entrained in an ionizable gas, comprising the steps of flowing the gas through a bounded flow path; charging the particles to a given electrical polarity by means of a first corona discharge at an upstream portion of the flow path; exposing the charged particles to a deposition electrical field at a downstream portion of the flow path, the deposition electrode of said field having the same polarity as the polarity of the charged particles; driving the charged particles toward the ground electrode of said field; depositing a portion of said charged particles on a dielectric surface positioned in said field, and determining by induction the accumulated surface charge density on the dielectric surface, the surface charge density Rho s being determined as a function of time by the equation Rho s ( epsilon mV/dm) (1-e t/ ) for measurement times of t << Tau , where epsilon m is the permittivity of the dielectric surface, V is the voltage of the deposition electrical field, dm is the thickness of the dielectric surface, t is the time, and Tau is the dielectric surface-charging time constant given by the relation where epsilon a is the permittivity of the air, da is the distance between the deposition field electrode and the dielectric surface, epsilon o is the permittivity of the gas, Eo is the first corona charging field, f is the fraction of saturation charge attained on the particulate matter, eta is the viscosity of the gas, delta is the bulk density of the particulate matter, and M is the mass of the particulate matter per unit volume of the gas.
Claim 11
Dependent Claim
33 words
A method in accordance with claim 8 comprising the additional step of converting electrically the accumulated charge determined by induction to a measurement of the particulate mass per unit volume of the gas.
Claim 12
Independent Claim
122 words
An apparatus for determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, the flow path having at least two conductive grounded surfaces, means for establishing a first electrical discharge in the upstream end of the flow path to charge the entrained particles, means for establishing a deposition electric field at a downstream portion of the flow path, said deposition electric field having a deposition electrode and a ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface positioned in the deposition electric field adjacent the ground electrode, and an induction electrode for measuring the accumulated charge on the dielectric surface.
Claim 13
Independent Claim
122 words
An apparatus for determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, the flow path having at least two conductive grounded surfaces, means for establishing a first electrical discharge in the upstream end of the flow path to charge the entrained particles, means for establishing a deposition electric field at a downstream portion of the flow path, said deposition electric field having a deposition electrode and a ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface positioned in the deposition electric field adjacent the ground electrode, and an induction electrode for measuring the accumulated charge on the dielectric surface.
Claim 14
Dependent Claim
35 words
An apparatus as defined in claim 10 wherein the means for establishing the first electrical discharge in the upstream end of the flow path comprise a corona discharge electrode and a constant current power supply.
Claim 15
Dependent Claim
33 words
An apparatus as defined in claim 10 further comprising means for establishing a second electrical discharge in the flow path, the second electrical discharge means positioned upstream of the first electrical discharge means.
Claim 16
Dependent Claim
25 words
An apparatus as defined in claim 12 wherein the second electrical discharge means comprises at least one corona discharge electrode and an electrical power supply.
Claim 17
Dependent Claim
33 words
An apparatus as defined in claim 10 further comprising means for establishing a third electrical discharge in the flow path, the third electrical discharge means positioned downstream of the deposition electric field means.
Claim 18
Dependent Claim
25 words
An aPparatus as defined in claim 14 wherein the third electrical discharge means comprises at least one corona discharge electrode and an electrical power supply.
Claim 19
Dependent Claim
35 words
An apparatus as defined in claim 10 further comprising means for separating out from the gas substantially all particles above a certain size, the separation means positioned at the upstream end of the flow path.
Claim 20
Dependent Claim
32 words
An apparatus as defined in claim 10 wherein the induction electrode is positioned below the ground electrode and the ground electrode is adapted to be adjustably removed from adjacent the dielectric surface.
Claim 21
Dependent Claim
67 words
An apparatus as defined in claim 10 wherein the accumulated charge measured by the induction electrode is converted electrically to a measurement of the mass of the particulate matter by an electrometer circuit, the accumulated charge and the mass of the particulate matter per unit volume of the gas measurements being linearly related and the accumulated charge measured being independent of the size of the particulate matter.
Claim 22
Dependent Claim
21 words
An apparatus as defined in claim 10 further comprising means for inducing a flow of the gas in the flow path.
Claim 23
Dependent Claim
24 words
An apparatus as defined in claim 19 wherein the flow inducing means comprises a fan positioned adjacent the downstream end of the flow path.
Claim 24
Independent Claim
271 words
An apparatus for determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, means for establishing an electrical discharge in the upstream end of the flow path to charge the entrained particles, means for establishing a deposition electric field at a downstream portion of the flow path, said deposition electric field having a deposition electrode and a ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface positioned in the deposition electric field between the deposition electrode and the ground electrode, and induction means for determining the accumulated surface charge density on the dielectric surface, the surface charge density Rho s being determined as a function of time by the equation Rho s ( epsilon mV/dm) ( 1-e t/) for measurement times of t << Tau , where epsilon m is the permittivity of the dielectric surface, V is the voltage of the deposition electrical field, dm is the thickness of the dielectric surface, t is the time, and Tau is the dielectric surface-charging time constant given by the relation where epsilon a is the permittivity of the air, da is the distance between the deposition field electrode and the dielectric surface, epsilon o is the permittivity of the gas, Eo is the first corona charging field, f is the fraction of saturation charge attained on the particulate matter, eta is the viscosity of the gas, delta is the bulk density of the particulate matter, and M is the mass of the particulate matter per unit volume of the gas.
Claim 25
Independent Claim
271 words
An apparatus for determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, means for establishing an electrical discharge in the upstream end of the flow path to charge the entrained particles, means for establishing a deposition electric field at a downstream portion of the flow path, said deposition electric field having a deposition electrode and a ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface positioned in the deposition electric field between the deposition electrode and the ground electrode, and induction means for determining the accumulated surface charge density on the dielectric surface, the surface charge density Rho s being determined as a function of time by the equation Rho s ( epsilon mV/dm) ( 1-e t/) for measurement times of t << Tau , where epsilon m is the permittivity of the dielectric surface, V is the voltage of the deposition electrical field, dm is the thickness of the dielectric surface, t is the time, and Tau is the dielectric surface-charging time constant given by the relation where epsilon a is the permittivity of the air, da is the distance between the deposition field electrode and the dielectric surface, epsilon o is the permittivity of the gas, Eo is the first corona charging field, f is the fraction of saturation charge attained on the particulate matter, eta is the viscosity of the gas, delta is the bulk density of the particulate matter, and M is the mass of the particulate matter per unit volume of the gas.
Claim 26
Dependent Claim
37 words
An apparatus as defined in claim 21 wherein the accumulated surface charge density determined is converted electrically to a measurement of the mass of the particulate matter per unit volume of the gas by an electrometer circuit.
Claim 27
Independent Claim
125 words
An apparatus for continuously determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, means for establishing an electrical discharge in the upstream end of the flow path to charge the entrained particles, means for establishing a deposition electric field at a downstream portion of the flow path, said deposition electric field having a deposition electrode and a ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface being movable, endless and positioned with at least one portion thereof iN the deposition electric field, means for moving the endless dielectric surface, and an induction electrode for measuring the accumulated charge on the dielectric surface.
Claim 28
Independent Claim
125 words
An apparatus for continuously determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, means for establishing an electrical discharge in the upstream end of the flow path to charge the entrained particles, means for establishing a deposition electric field at a downstream portion of the flow path, said deposition electric field having a deposition electrode and a ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface being movable, endless and positioned with at least one portion thereof iN the deposition electric field, means for moving the endless dielectric surface, and an induction electrode for measuring the accumulated charge on the dielectric surface.
Claim 29
Dependent Claim
47 words
An apparatus as defined in claim 23 wherein the endless dielectric surface is attached to a rotatable cylinder, the means for moving the endless dielectric surface is connected to the cylinder, and the cylinder is grounded and acts as the ground electrode for the deposition electric field.
Claim 30
Dependent Claim
20 words
An apparatus as defined in claim 23 further comprising means for discharging the accumulated charge on the endless dielectric surface.
Claim 31
Dependent Claim
38 words
An apparatus as defined in claim 23 wherein the endless dielectric surface comprises an endless belt positioned around at least two rollers and the means for moving the surface is connected to at least one of the rollers.
Claim 32
Independent Claim
185 words
An apparatus for determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, the flow path having at least two grounded conductive surfaces, a first corona discharge electrode, power supply means for establishing a corona discharge from the first corona discharge electrode to the grounded conductive surfaces in the upstream end of the flow path to charge the entrained particles, a deposition field electrode and a deposition field ground electrode positioned at a downstream portion of the flow path, power supply means for establishing a deposition electric field between the deposition electrode and the ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface positioned in the deposition electric field adjacent the ground electrode, an induction electrode for measuring the accumulated charge on the dielectric surface, the induction electrode positioned below the ground electrode, and an electrometer circuit for receiving the accumulated charge measured by the induction electrode and converting the measurement to a measurement of the particulate mass per unit volume of gas.
Claim 33
Independent Claim
185 words
An apparatus for determining the mass per unit volume of particles entrained in an ionizable gas comprising means defining a bounded flow path for passage of the gas, the flow path having at least two grounded conductive surfaces, a first corona discharge electrode, power supply means for establishing a corona discharge from the first corona discharge electrode to the grounded conductive surfaces in the upstream end of the flow path to charge the entrained particles, a deposition field electrode and a deposition field ground electrode positioned at a downstream portion of the flow path, power supply means for establishing a deposition electric field between the deposition electrode and the ground electrode, a dielectric surface for collecting the charges associated with the particles, the dielectric surface positioned in the deposition electric field adjacent the ground electrode, an induction electrode for measuring the accumulated charge on the dielectric surface, the induction electrode positioned below the ground electrode, and an electrometer circuit for receiving the accumulated charge measured by the induction electrode and converting the measurement to a measurement of the particulate mass per unit volume of gas.
Claim 34
Dependent Claim
78 words
An apparatus as defined in claim 27 wherein the means defining the bounded flow path, the corona discharge electrode, the deposition field electrode and the dielectric surface are contained in a sampling module, the deposition field ground electrode, the induction electrode and the electrometer circuit are contained in an electrometer module, and the corona discharge power supply means and the deposition field power supply means are contained in a supply module, the three modules adapted to be separable.
Claim 35
Dependent Claim
25 words
An apparatus as defined in claim 28 wherein the power supply means for the first corona discharge electrode is a constant current power supply means.
Claim 36
Dependent Claim
39 words
An apparatus as defined in claim 28 further comprising a fan for inducing a flow of gas in the flow path, the fan positioned in the supply module and in communication with the downstream end of the flow path.
Claim 37
Dependent Claim
37 words
An apparatus as defined in claim 27 further comprising a second corona discharge electrode in the flow path to discharge the charged entrained particles, the second corona discharge electrode positioned upstream of the first corona discharge electrode.
Claim 38
Dependent Claim
36 words
An apparatus as defined in claim 27 further comprising a third corona discharge electrode in the flow path to discharge the charged entrained particles, the third corona discharge electrode positioned downstream of the deposition electric field.
Claim 39
Dependent Claim
71 words
An apparatus as defined in claim 27 further comprising a holding plate and a lance attached to the holding plate, the means defining the bounded flow path, the corona discharge electrode, the deposition field electrode and the dielectric surface contained in a sampling module, and the sampling module positioned on the holding plate whereby the mass per unit volume of particles entrained in the gas in a stack can be determined.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-27 | 1976-08-28 | 1977-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-27 | 1980-08-28 | 1981-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-27 | 1984-08-28 | 1985-02-27 | $7700.00 | Window Closed / Lapsed |