US4445911A
Expired / Lapsed
US
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Method of controlling operation of an electrostatic precipitator
Assignee: FLSmidth and Co AS
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Filing: 1981-12-15
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Granted: 1984-05-01
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Expires: 2001-12-15
Abstract
Abstract A method is disclosed for controlling the DC voltage of an electrostatic precipitator having electrodes energized by a preset DC voltage in which the preset DC voltage has pulses superimposed thereon. According to the method, the pulses are periodically turned off. Thereafter, the corona discharge current caused by the DC voltage is measured and compared against a preset value. Thereafter, the DC voltage is adjusted in dependence upon the measured corona discharge current by it being increased or decreased depending upon whether the discharge current is lower or higher than the preset value.
Inventors
- 👤 Leif Lind
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:09
CPC Classifications
B; B03; B03C; B03C3/00; B03C3/34; B03C3/66; B03C3/68; Y; Y10; Y10S; Y10S323/00; Y10S323/903
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
102 words
A method of controlling the DC-voltage in an electrostatic precipitator having electrodes energized by pulses superimposed upon a preset DC-voltage, which comprises: periodically eliminating said pulses and thereafter measuring a corona discharge current between said electrodes; comparing said measured corona discharge current against a predetermined value; and selectively adjusting the DC-voltage in accordance with said measured corona discharge current so as to maintain the DC-voltage at approximately the corona extinction voltage by increasing the DC-voltage when the measured discharge current is lower than said predetermined value and by decreasing the DC-voltage when the measured discharge current is higher than said predetermined value.
Claim 2
Independent Claim
102 words
A method of controlling the DC-voltage in an electrostatic precipitator having electrodes energized by pulses superimposed upon a preset DC-voltage, which comprises: periodically eliminating said pulses and thereafter measuring a corona discharge current between said electrodes; comparing said measured corona discharge current against a predetermined value; and selectively adjusting the DC-voltage in accordance with said measured corona discharge current so as to maintain the DC-voltage at approximately the corona extinction voltage by increasing the DC-voltage when the measured discharge current is lower than said predetermined value and by decreasing the DC-voltage when the measured discharge current is higher than said predetermined value.
Claim 3
Dependent Claim
56 words
The method according to claim 1 wherein the DC-voltage as a function of time is permanently increased by a slight slope, and the increase is maintained when the discharge current is lower than the predetermined value, and the DC-voltage is decreased by a discrete value if the discharge current measured is higher than the predetermined value.
Claim 4
Dependent Claim
24 words
The method according to claim 3 wherein the decrease of the original DC-value due to the controlling is made by a preselected discrete value.
Claim 5
Dependent Claim
53 words
The method according to claim 3 wherein the pulses, when the DC-level is selectively in either of a first state when the DC-level is increasing and a second state when the DC-level is decreasing, are regulated to keep the sum of the DC-voltage and the pulse-voltage constant before and after the measuring period.
Claim 6
Dependent Claim
87 words
The method according to claim 1 wherein the DC-voltage as a function of time can be selectively in either of a first state and a second state wherein the DC-voltage is permanently increased or decreased respectively with a slight slope, said increase being maintained and said decrease being changed into an increase when the discharge current measured is lower than the predetermined value, and said decrease being maintained and said increase being changed into a decrease when the discharge current measured is higher than the predetermined value.
Claim 7
Independent Claim
34 words
The method according to any of claims 1, 3 and 4 wherein the DC-voltage is temporarily increased by a predetermined amount and maintained at said elevated level during the measuring of the corona current.
Claim 8
Dependent Claim
23 words
The method according to claim 5 wherein the pulses are not turned off until the temporary increase of the DC-voltage has been established.
Claim 9
Dependent Claim
23 words
The method according to claim 6 wherein the pulses are turned on again towards the end of the period of temporary increased DC-level.
Claim 10
Dependent Claim
37 words
The method according to claim 8 wherein said selective increase and decrease of the original DC-voltage due to the controlling are each determined by a closed loop control regulating the DC-voltage to create a predetermined corona current.
Claim 11
Dependent Claim
27 words
The method according to claim 8 wherein said selective increase and decrease of the original DC-value due to the controlling is made by a preselected discrete value.
Claim 12
Dependent Claim
53 words
The method according to claim 8 wherein the pulses, when the DC-level is selectively in either of a first state when the DC-level is increasing and a second state when the DC-level is decreasing, are regulated to keep the sum of the DC-voltage and the pulse-voltage constant before and after the measuring period.
Claim 13
Dependent Claim
37 words
The method according to claim 6 wherein said selective increase and decrease of the original DC-voltage due to the controlling are each determined by a closed loop control regulating the DC-voltage to create a predetermined corona current.
Claim 14
Dependent Claim
27 words
The method according to claim 6 wherein said selective increase and decrease of the original DC-value due to the controlling is made by a preselected discrete value.
Claim 15
Dependent Claim
53 words
The method according to claim 6 wherein the pulses, when the DC-level is selectively in either of a first state when the DC-level is increasing and a second state when the DC-level is decreasing, are regulated to keep the sum of the DC-voltage and the pulse-voltage constant before and after the measuring period.
Claim 16
Dependent Claim
23 words
The method according to claim 5 wherein the pulses are turned on again towards the end of the period of temporary increased DC-level.
Claim 17
Dependent Claim
37 words
The method according to claim 7 wherein said selective increase and decrease of the original DC-voltage due to the controlling are each determined by a closed loop control regulating the DC-voltage to create a predetermined corona current.
Claim 18
Dependent Claim
27 words
The method according to claim 7 wherein said selective increase and decrease of the original DC-value due to the controlling is made by a preselected discrete value.
Claim 19
Dependent Claim
53 words
The method according to claim 7 wherein the pulses, when the DC-level is selectively in either of a first state when the DC-level is increasing and a second state when the DC-level is decreasing, are regulated to keep the sum of the DC-voltage and the pulse-voltage constant before and after the measuring period.
Claim 20
Dependent Claim
37 words
The method according to claim 5 wherein said selective increase and decrease of the original DC-voltage due to the controlling are each determined by a closed loop control regulating the DC-voltage to create a predetermined corona current.
Claim 21
Dependent Claim
27 words
The method according to claim 5 wherein said selective increase and decrease of the original DC-value due to the controlling is made by a preselected discrete value.
Claim 22
Dependent Claim
53 words
The method according to claim 5 wherein the pulses, when the DC-level is selectively in either of a first state when the DC-level is increasing and a second state when the DC-level is decreasing, are regulated to keep the sum of the DC-voltage and the pulse-voltage constant before and after the measuring period.
Claim 23
Dependent Claim
37 words
The method according to claim 4 wherein said selective increase and decrease of the original DC-voltage due to the controlling are each determined by a closed loop control regulating the DC-voltage to create a predetermined corona current.
Claim 24
Dependent Claim
53 words
The method according to claim 4 wherein the pulses, when the DC-level is selectively in either of a first state when the DC-level is increasing and a second state when the DC-level is decreasing, are regulated to keep the sum of the DC-voltage and the pulse-voltage constant before and after the measuring period.
Claim 25
Dependent Claim
37 words
The method according to claim 1 wherein said selective increase and decrease of the original DC-voltage due to the controlling are each determined by a closed loop control regulating the DC-voltage to create a predetermined corona current.
Claim 26
Dependent Claim
27 words
The method according to claim 1 wherein said selective increase and decrease of the original DC-value due to the controlling is made by a preselected discrete value.
Claim 27
Dependent Claim
53 words
The method according to claim 1 wherein the pulses, when the DC-level is selectively in either of a first state when the DC-level is increasing and a second state when the DC-level is decreasing, are regulated to keep the sum of the DC-voltage and the pulse-voltage constant before and after the measuring period.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-01 | 1987-10-31 | 1988-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-01 | 1991-10-31 | 1992-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-01 | 1995-10-31 | 1996-05-01 | $7700.00 | Window Closed / Lapsed |