CA1172687A - Method of controlling operation of an electrostatic precipitator - Google Patents
Method of controlling operation of an electrostatic precipitatorInfo
- Publication number
- CA1172687A CA1172687A CA000392290A CA392290A CA1172687A CA 1172687 A CA1172687 A CA 1172687A CA 000392290 A CA000392290 A CA 000392290A CA 392290 A CA392290 A CA 392290A CA 1172687 A CA1172687 A CA 1172687A
- Authority
- CA
- Canada
- Prior art keywords
- spark
- over
- voltage
- pulse
- reducing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000012717 electrostatic precipitator Substances 0.000 title claims abstract description 9
- 239000012716 precipitator Substances 0.000 claims abstract description 22
- 230000009467 reduction Effects 0.000 claims abstract description 7
- 229940035564 duration Drugs 0.000 claims 6
- 230000001276 controlling effect Effects 0.000 description 7
- 230000000875 corresponding effect Effects 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 230000008033 biological extinction Effects 0.000 description 2
- 230000002301 combined effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- QHGVXILFMXYDRS-UHFFFAOYSA-N pyraclofos Chemical compound C1=C(OP(=O)(OCC)SCCC)C=NN1C1=CC=C(Cl)C=C1 QHGVXILFMXYDRS-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/66—Applications of electricity supply techniques
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/34—Constructional details or accessories or operation thereof
- B03C3/66—Applications of electricity supply techniques
- B03C3/68—Control systems therefor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S323/00—Electricity: power supply or regulation systems
- Y10S323/903—Precipitators
Abstract
Abstract A method is disclosed for controlling the operating parameters of an electrostatic precipitator of the type having electrodes energized by pulses superimposed upon a DC-voltage.
According to the method, the pulse height (i.e., amplitude) is continuously increased at a predetermined rate and spark-overs are thereby detected as reductions in the precipitator-voltage below a selectable set value and are sorted in different types according to the time of their occurrence and duration.
Thereafter, the operating parameters of the precipitator are altered in dependence upon the characteristics of the actual spark-over.
According to the method, the pulse height (i.e., amplitude) is continuously increased at a predetermined rate and spark-overs are thereby detected as reductions in the precipitator-voltage below a selectable set value and are sorted in different types according to the time of their occurrence and duration.
Thereafter, the operating parameters of the precipitator are altered in dependence upon the characteristics of the actual spark-over.
Description
~ 1 72~87 s65~ ol METHOD OF _ONTROLLING OPE ATION
OF AN ELECTROSTATIC PRECIPITATOR
Technica~ Field The invention relates to a method of controlling the operating parameters of an electrostatic precipitator which is energized by voltage pulses superimposed on a DC-voltage.
Background Art It is a documented fact that the performance of conventional two-electrode precipitators can be improved by pulse energization where high voltage pulses of suitable duration and repetition rate are superimposed on an operating DC-voltage.
For practical application, automatic control of ~;~ - any precipitator energization system is of major importance in order to secure optimum performance under changing operating conditions and to eliminate the need for supervision of the setting of the electrical parameters.
::
With conventional DC energization, commonly used - ~ control systems regulatejprecipitator v,oltage and current, and in general ~erms, the strategy is aimed at giving maximum voltage and current within the limits set by spark-over conditions. The possibilities of different strategies are extremely limited, since the precipitator voltage is the only parameter which can be regulated independently.
i ~726~'~
In contradistinction, pulse energization allows independent control of the following parameters:
1. DC Voltage level
OF AN ELECTROSTATIC PRECIPITATOR
Technica~ Field The invention relates to a method of controlling the operating parameters of an electrostatic precipitator which is energized by voltage pulses superimposed on a DC-voltage.
Background Art It is a documented fact that the performance of conventional two-electrode precipitators can be improved by pulse energization where high voltage pulses of suitable duration and repetition rate are superimposed on an operating DC-voltage.
For practical application, automatic control of ~;~ - any precipitator energization system is of major importance in order to secure optimum performance under changing operating conditions and to eliminate the need for supervision of the setting of the electrical parameters.
::
With conventional DC energization, commonly used - ~ control systems regulatejprecipitator v,oltage and current, and in general ~erms, the strategy is aimed at giving maximum voltage and current within the limits set by spark-over conditions. The possibilities of different strategies are extremely limited, since the precipitator voltage is the only parameter which can be regulated independently.
i ~726~'~
In contradistinction, pulse energization allows independent control of the following parameters:
1. DC Voltage level
2. Pulse voltage level
3. Pulse repetition frequency 4O Pulse widt4 The possibility of combining the setting of several parameters enables development of highly efficient control strategies, if the phenomena taking place in the precipitator are measured and interpreted correctly.
~5 I have invented a method of controlling these parameters to obtain an optimum operation of a pulse energized precipitator. More particularly, I have invented a method of controlling the pulse height in a manner to maintain the sum of the DC-voltage and the pulse height as high as possible, that is as high as it can be without causing an excessive number of spark-overs, when the DC-voltage is set or regulated to an optimal value.
Disclosure of the Invention The present invention relates to a method of controlling the operating parameters of an electrostatic ; precipitator having electrodéslenergized by pulses superimposed upon a DC-voltage which comprises, ~ 3~ continuously increasing the height of the pulses according ;~ to a predetermined rate, determining reductions in the precipitator-~oltage below a preselected value in order to determine spark-over thereof, categorizing the spark-overs according to the time of their occurrence and duration~
` ~ 35 .
2 6 ~
--3~
and adjusting the operating parameters of the electrostatic precipitator in dependence upon the characteristics of the actual spark-over~
Thus, according to the invention, such control can be achieved by allowing the height of the pulses to increase linearly with a preselected slope; detecting spark-overs as drops in the ~recipitator-voltage below a preselected set value; sorting the voltage drops in different types according to the time of their occurrence and the duration of the voltage drop; and modifying the operating parameters of the precipitator in dependance upon the type of spark-over.
When a spark-over occurs, the voltage pulses may be stopped for the period of time during which the precipitator voltage is below the set value plus a preselected period thereafter.
The spark-overs can be sorted into the following four types:
(a) spark-over occuring during a pulse and causing a voltage drop of short duration;
(b) spark-over occurring during a pulse and causing a voltage drop of long duration;
i. ,. ~.
(c~ spark-over occurring between pulses and causing a voltage drop of long duration;
(d) spark-over occurring between pulses and causing a voltage drop of short duration.
~ ~ ~ 2 ~
As a type (a) spark-over may indicate that the pulse voltage is too high, this type of pulse can be arranged to cause the pulse height to be reduced by a certain amount.
A type (b) spark-over can be arranged to cause the pulse height to be reduced and further causes the DC-~IT (HT, i.e., high tension) supply to be turned off for a certain period.
; A type (c) spark-over may be arranged to cause one or more of the following precautions to be taken:
-Reduction of the DC-level by a certain predetermined amount and subsequently raising of it again;
-Reduction of the pulse repetition frequency by a certain amount and subsequently raising of it again;
-Reduction of the set value for the precipitator dis-~ 15 charge current by a certain amount and subsequently raising of ; it again;
-Increase of the plateau voltage where the DC-voltage is controlled by using a periodically occuring plateau of increased voltage.
A type (d) spark-over may cause a similar reaction as a type (c) spark-over, or no reaction may be caused except for the pulse voltage blocking which is caused by any spark-over.
l 1 7 ~
Brief Description of the Drawings Preferred embodiments of the invention will now be des-cribed with reference to the accompanying drawings wherein:
Fig. l illustrates schematically, pulses superimposed on a DC-voltage for energizing an electrostatic precipi-ta-tor;
Fig. 2 illustrates schematically, a voltage/time diagram of a classification of spark-overs during a pulse; and Fig. 3 illustrates schematically, a voltage/time diagram of a classification of spark-overs between pulses.
Best Mode For Carrying Out the Invention Referring to Fig. 1, there is shown schematically volt-age pulses of height Up superimposed on a DC-voltage UDc for energizing an electrostatic precipitator. The Fig. shows the voltage on the discharge electxode as a function of time. This voltage will usually be negative, so what is depicted here is the numeric (or absolute) value of the voltage. In the follow-ing explanation voltage levels and increases or decreases ac-cordingly refer to the numerical value of the voltage.
In order to fully benefit from the pulse technique, it is important that the DC-level is maintained as high as possi-ble, that is, slightly below the corona extinction voltage, or at a voltage creating a certain corona current depending on actual application.
- 6 _ ll 7~6~7 For applications with high resistivity dust, optimum performance is obtained with the DC-voltage maintained slightly below the corona extinction voltage. The object is -to ex-tin-guish completely the corona discharge after each pulse. Com-bined with suitably long intervals between pulses, this allowsthe DC field to remove the ion space charge from the interelec-trode spacing, before the next pulse is applied, and thus per-mits high pulse peak voltages without sparking. Furthermore, it allows full control of the corona discharge current by means of pulse height and repetition frequency.
In applications with lower resistivity dust, a certain amount of corona discharge at the DC-voltage level is advant-ageous to secure a continuous current flow through the precipi-tated dust.
When the DC-voltage is controlled to its optimum, the ; optimal pulse height is established and controlled on the basis of the demand for the highest possible sum of the DC plus pulse voltage by means of the procedure described hereinbelow.
At start-up, the voltage pulses are inactivated until the DC-voltage level has reached the desired value. Thereafter, the pulse height is increased to a start value (selectable, for ex-ample, between 33 and 67% of the maximum pulse height).
From this value the pulse amplitude increases continuous-ly until a spark-over occurs during a pulse. The amplitude of the pulses increases with an adjusted ` ` 1~26~7 rate of rise. After a spark-over the pulse amplitude is reduced by a certain amount (selectable, for example, between 1 and 5%
of the rated value), and thereafter increased 1inearly with the same rate of rise (corresponding, for example, to a variation from 0 to rated value within a selectable period between 1 and 10 min). The pulse height can be limited to a maximum value lower than the ra-ted value (selectable, for example, between 50 and 100% of the rated value).
When the DC plus pulse voltage is brought to the opti-mum value, the corona discharge current is controlled to main-tain a set value (selectable, for example, between 20 and 100%
of the rated generator current) by a closed loop control con-trolling the repetition frequency.
A lower and upper limit can be set in the total range of the pulse repetition frequency.
In another embodiment, the corona discharge current is measured with selectable time intervals, and the pulse repeti-tion frequency is increased or decreased by a selectable value,depending upon whether the measured value is lower or higher than a set value.
At start-up, the pulse repetition frequency control is inactivated until the DC-voltage level has reached the desired value as described. The above men-tioned setting of a lower li-mit is used as an initial value in the embodiment, where the corona discharge current is controlled.
As outlined above, the controlling of the operating para-meters of the precipitator is to a great extent based upon the detection of spark-overs, as L L 7 ~
.
reductions in the precipitator voltage below a set value, controlling the different parameters of the precipitator, depending upon the time for and the duration of such voltage reductions.
Fig. 2 schematically shows a spark-over during one of a series of linearly increasing pulses. The pulse period is defined in the control device as a time interval equal to the pulse width after the ignition of the switch element initiating the application of a pulse. The control device determines the occurrence of a spark-over if the precipitator voltage falls below a certain level Uset (selectable for example, between 0-50kV). If the voltage within a certain period [selectable for example, between 20 ~s (i.e., microseconds) and 20 ms (i~e., milliseconds)] returns to a value ahove the set level, the spark-over is classified as type I. If not, it is classified as type II.
In Fig. 2, the voltage is shown as falling below the level Uset. The curve ~a) shows a type I
spark-over, as the voltage increases over the set level Uset before the lapse of the set time, tset. In the same way the curve (b) is seen to represent a type II
spark-over, as Uset is not reached within the time period tset.
Correspondinglyl Fig. 3 shows.a spark-over between pulses, the curve (d) represents a type I
spark-over, and curve (c) shows a type II spark-over.
The spark-overs are sorted in four categories and at each spark-over different precautions are taken with respect to its category.
~ i L 7 ~ fi ~ 7 g At all spark-overs, the voltage pulses are turned off un-til -the DC voltage again r;ses above the voltage set value and for a selectable time thereafter. E'or a type I spark-over dur-ing a pulse, the pulse height must be reduced. This is done by a certain amount (selectable for example, between 1 and 5% of the rated pulse height).
A type I spark-over between pulses can also be reacted to as to a corresponding type II as will be described, or -the above mentioned turning off of the pulse voltage, taking place after all spark-overs, can be the only reaction.
A type II spark-over causes the DC-HT supply to be turned off for a certain period (selectable, for example, between 10 and 500 ms). This is to extinguish the current and thus elimi-nate the conduction path created by the spark-over. If it occurs during a pulse it further causes the reduction of pulse height described above.
If it occurs between pulses, the turning off of the DC-~T supply may be the only reaction, or one or more of the following precautions may be taken, depending on the main reason for the spark-over in the actual situation, which is the combined effect of the electrical fièld from the DC-voltage and the co-rona discharge current.
a. The DC voltage level is reduced by a certain amount (selectable, for example, between 0 and 6Kv).
b. The pulse repetition frequency is reduced by a cer-tain amount (selectable, for example, between 5 and 50% of the value previous to the spark-over).
;
`" i L 7;~6~7 c. The set value of -the discharge current is reduced by a certain amount (selectable, for example, between 5 and 25% of the value previous to the spark-over). HereaEter, the set value is either maintained or raised linearly with a given slope (cor-responding, for example, to a variation between 0 and 100% ofthe maximum generator current within a period selectable between 1 and 10 min).
d. If the ~C-voltage is controlled using a periodically occuring finger of a preset increased voltage, this finger-vol-tage is increased.
~5 I have invented a method of controlling these parameters to obtain an optimum operation of a pulse energized precipitator. More particularly, I have invented a method of controlling the pulse height in a manner to maintain the sum of the DC-voltage and the pulse height as high as possible, that is as high as it can be without causing an excessive number of spark-overs, when the DC-voltage is set or regulated to an optimal value.
Disclosure of the Invention The present invention relates to a method of controlling the operating parameters of an electrostatic ; precipitator having electrodéslenergized by pulses superimposed upon a DC-voltage which comprises, ~ 3~ continuously increasing the height of the pulses according ;~ to a predetermined rate, determining reductions in the precipitator-~oltage below a preselected value in order to determine spark-over thereof, categorizing the spark-overs according to the time of their occurrence and duration~
` ~ 35 .
2 6 ~
--3~
and adjusting the operating parameters of the electrostatic precipitator in dependence upon the characteristics of the actual spark-over~
Thus, according to the invention, such control can be achieved by allowing the height of the pulses to increase linearly with a preselected slope; detecting spark-overs as drops in the ~recipitator-voltage below a preselected set value; sorting the voltage drops in different types according to the time of their occurrence and the duration of the voltage drop; and modifying the operating parameters of the precipitator in dependance upon the type of spark-over.
When a spark-over occurs, the voltage pulses may be stopped for the period of time during which the precipitator voltage is below the set value plus a preselected period thereafter.
The spark-overs can be sorted into the following four types:
(a) spark-over occuring during a pulse and causing a voltage drop of short duration;
(b) spark-over occurring during a pulse and causing a voltage drop of long duration;
i. ,. ~.
(c~ spark-over occurring between pulses and causing a voltage drop of long duration;
(d) spark-over occurring between pulses and causing a voltage drop of short duration.
~ ~ ~ 2 ~
As a type (a) spark-over may indicate that the pulse voltage is too high, this type of pulse can be arranged to cause the pulse height to be reduced by a certain amount.
A type (b) spark-over can be arranged to cause the pulse height to be reduced and further causes the DC-~IT (HT, i.e., high tension) supply to be turned off for a certain period.
; A type (c) spark-over may be arranged to cause one or more of the following precautions to be taken:
-Reduction of the DC-level by a certain predetermined amount and subsequently raising of it again;
-Reduction of the pulse repetition frequency by a certain amount and subsequently raising of it again;
-Reduction of the set value for the precipitator dis-~ 15 charge current by a certain amount and subsequently raising of ; it again;
-Increase of the plateau voltage where the DC-voltage is controlled by using a periodically occuring plateau of increased voltage.
A type (d) spark-over may cause a similar reaction as a type (c) spark-over, or no reaction may be caused except for the pulse voltage blocking which is caused by any spark-over.
l 1 7 ~
Brief Description of the Drawings Preferred embodiments of the invention will now be des-cribed with reference to the accompanying drawings wherein:
Fig. l illustrates schematically, pulses superimposed on a DC-voltage for energizing an electrostatic precipi-ta-tor;
Fig. 2 illustrates schematically, a voltage/time diagram of a classification of spark-overs during a pulse; and Fig. 3 illustrates schematically, a voltage/time diagram of a classification of spark-overs between pulses.
Best Mode For Carrying Out the Invention Referring to Fig. 1, there is shown schematically volt-age pulses of height Up superimposed on a DC-voltage UDc for energizing an electrostatic precipitator. The Fig. shows the voltage on the discharge electxode as a function of time. This voltage will usually be negative, so what is depicted here is the numeric (or absolute) value of the voltage. In the follow-ing explanation voltage levels and increases or decreases ac-cordingly refer to the numerical value of the voltage.
In order to fully benefit from the pulse technique, it is important that the DC-level is maintained as high as possi-ble, that is, slightly below the corona extinction voltage, or at a voltage creating a certain corona current depending on actual application.
- 6 _ ll 7~6~7 For applications with high resistivity dust, optimum performance is obtained with the DC-voltage maintained slightly below the corona extinction voltage. The object is -to ex-tin-guish completely the corona discharge after each pulse. Com-bined with suitably long intervals between pulses, this allowsthe DC field to remove the ion space charge from the interelec-trode spacing, before the next pulse is applied, and thus per-mits high pulse peak voltages without sparking. Furthermore, it allows full control of the corona discharge current by means of pulse height and repetition frequency.
In applications with lower resistivity dust, a certain amount of corona discharge at the DC-voltage level is advant-ageous to secure a continuous current flow through the precipi-tated dust.
When the DC-voltage is controlled to its optimum, the ; optimal pulse height is established and controlled on the basis of the demand for the highest possible sum of the DC plus pulse voltage by means of the procedure described hereinbelow.
At start-up, the voltage pulses are inactivated until the DC-voltage level has reached the desired value. Thereafter, the pulse height is increased to a start value (selectable, for ex-ample, between 33 and 67% of the maximum pulse height).
From this value the pulse amplitude increases continuous-ly until a spark-over occurs during a pulse. The amplitude of the pulses increases with an adjusted ` ` 1~26~7 rate of rise. After a spark-over the pulse amplitude is reduced by a certain amount (selectable, for example, between 1 and 5%
of the rated value), and thereafter increased 1inearly with the same rate of rise (corresponding, for example, to a variation from 0 to rated value within a selectable period between 1 and 10 min). The pulse height can be limited to a maximum value lower than the ra-ted value (selectable, for example, between 50 and 100% of the rated value).
When the DC plus pulse voltage is brought to the opti-mum value, the corona discharge current is controlled to main-tain a set value (selectable, for example, between 20 and 100%
of the rated generator current) by a closed loop control con-trolling the repetition frequency.
A lower and upper limit can be set in the total range of the pulse repetition frequency.
In another embodiment, the corona discharge current is measured with selectable time intervals, and the pulse repeti-tion frequency is increased or decreased by a selectable value,depending upon whether the measured value is lower or higher than a set value.
At start-up, the pulse repetition frequency control is inactivated until the DC-voltage level has reached the desired value as described. The above men-tioned setting of a lower li-mit is used as an initial value in the embodiment, where the corona discharge current is controlled.
As outlined above, the controlling of the operating para-meters of the precipitator is to a great extent based upon the detection of spark-overs, as L L 7 ~
.
reductions in the precipitator voltage below a set value, controlling the different parameters of the precipitator, depending upon the time for and the duration of such voltage reductions.
Fig. 2 schematically shows a spark-over during one of a series of linearly increasing pulses. The pulse period is defined in the control device as a time interval equal to the pulse width after the ignition of the switch element initiating the application of a pulse. The control device determines the occurrence of a spark-over if the precipitator voltage falls below a certain level Uset (selectable for example, between 0-50kV). If the voltage within a certain period [selectable for example, between 20 ~s (i.e., microseconds) and 20 ms (i~e., milliseconds)] returns to a value ahove the set level, the spark-over is classified as type I. If not, it is classified as type II.
In Fig. 2, the voltage is shown as falling below the level Uset. The curve ~a) shows a type I
spark-over, as the voltage increases over the set level Uset before the lapse of the set time, tset. In the same way the curve (b) is seen to represent a type II
spark-over, as Uset is not reached within the time period tset.
Correspondinglyl Fig. 3 shows.a spark-over between pulses, the curve (d) represents a type I
spark-over, and curve (c) shows a type II spark-over.
The spark-overs are sorted in four categories and at each spark-over different precautions are taken with respect to its category.
~ i L 7 ~ fi ~ 7 g At all spark-overs, the voltage pulses are turned off un-til -the DC voltage again r;ses above the voltage set value and for a selectable time thereafter. E'or a type I spark-over dur-ing a pulse, the pulse height must be reduced. This is done by a certain amount (selectable for example, between 1 and 5% of the rated pulse height).
A type I spark-over between pulses can also be reacted to as to a corresponding type II as will be described, or -the above mentioned turning off of the pulse voltage, taking place after all spark-overs, can be the only reaction.
A type II spark-over causes the DC-HT supply to be turned off for a certain period (selectable, for example, between 10 and 500 ms). This is to extinguish the current and thus elimi-nate the conduction path created by the spark-over. If it occurs during a pulse it further causes the reduction of pulse height described above.
If it occurs between pulses, the turning off of the DC-~T supply may be the only reaction, or one or more of the following precautions may be taken, depending on the main reason for the spark-over in the actual situation, which is the combined effect of the electrical fièld from the DC-voltage and the co-rona discharge current.
a. The DC voltage level is reduced by a certain amount (selectable, for example, between 0 and 6Kv).
b. The pulse repetition frequency is reduced by a cer-tain amount (selectable, for example, between 5 and 50% of the value previous to the spark-over).
;
`" i L 7;~6~7 c. The set value of -the discharge current is reduced by a certain amount (selectable, for example, between 5 and 25% of the value previous to the spark-over). HereaEter, the set value is either maintained or raised linearly with a given slope (cor-responding, for example, to a variation between 0 and 100% ofthe maximum generator current within a period selectable between 1 and 10 min).
d. If the ~C-voltage is controlled using a periodically occuring finger of a preset increased voltage, this finger-vol-tage is increased.
Claims (17)
1. A method of controlling the operating parameters of an electrostatic precipitator having electrodes energized by pulses superimposed upon a DC-voltage which comprises:
continuously increasing the height of said pulses according to a predetermined rate;
determining reductions in the precipitator-voltage below a preselected value in order to determine spark-over thereof;
categorizing said spark-overs according to the time of their occurrence and duration; and adjusting the operating parameters of the electrostatic precipitator in dependence upon the characteristics of the actual spark-over.
continuously increasing the height of said pulses according to a predetermined rate;
determining reductions in the precipitator-voltage below a preselected value in order to determine spark-over thereof;
categorizing said spark-overs according to the time of their occurrence and duration; and adjusting the operating parameters of the electrostatic precipitator in dependence upon the characteristics of the actual spark-over.
2. A method of controlling the operating parameters of an electrostatic precipitator energized by pulses superimposed on a DC-voltage, characterized in that the pulse height is continuously increased with a preselected slope, spark-overs are detected as reductions in the precipitator-voltage below a selectable set value and are sorted in different types according to the time of their occurrence and their duration, and the operating parameters of the precipitator are altered, depending upon the type of an actual spark-over.
.
.
3. The method according to claim 1, wherein any spark-over causes the pulse voltage to be turned off for a period beyond the time in which the precipitator voltage is below the set value.
4. The method according to any of claims 1 or 2, wherein at least four types of spark-overs are as follows:
a) during a pulse and causing voltage drop of short duration.
b) during a pulse and causing voltage drop of longer duration.
c) between pulses and causing voltage drop of longer duration.
d) between pulses and causing voltage drop of short duration.
a) during a pulse and causing voltage drop of short duration.
b) during a pulse and causing voltage drop of longer duration.
c) between pulses and causing voltage drop of longer duration.
d) between pulses and causing voltage drop of short duration.
5. The method according to claim 1 wherein a spark-over occurring during a pulse and causing voltage drop of short duration causes the pulse height to be reduced by a predetermined amount.
6. The method according to claim 2 wherein a spark-over occurring during a pulse and causing voltage drop of short duration causes the pulse height to be reduced by a predetermined amount.
7. The method according to claim 3 wherein a spark-over occurring during a pulse and causing voltage drop of short duration causes the pulse height to be reduced by a predetermined amount.
8. The method according to claim 1 wherein a spark-over occurring during a pulse and causing voltage drop of longer duration causes the pulse height to be reduced and the DC-HT
supply to be turned off for a predetermined time period.
supply to be turned off for a predetermined time period.
9. The method according to claim 2 wherein a spark-over oc-curring during a pulse and causing voltage drop of longer dura-tion causes the pulse height to be reduced and the DC-HT supply to be turned off for a predetermined time period.
10. The method according to claim 3 wherein a spark-over oc-curring during a pulse and causing voltage drop of longer dura-tion causes the pulse height to be reduced and the DC-HT supply to be turned off for a predetermined time period.
11. The method according to claim 1 wherein a spark-over oc-curring between pulses and causing voltage drop of longer dura-tion necessitates taking one or more of the following precau-tions:
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and sub-sequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subse-quently raising it; and D) increasing the finger voltage in a DC-voltage control-ler using a periodically occuring finger of increased voltage.
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and sub-sequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subse-quently raising it; and D) increasing the finger voltage in a DC-voltage control-ler using a periodically occuring finger of increased voltage.
12. The method according to claim 2 wherein a spark-over oc-curring between pulses and causing voltage drop of longer dura-tion necessitates taking one or more of the following precau-tions:
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and subsequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and subsequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
13. The method according to claim 3 wherein a spark-over occurring between pulses and causing voltage drop of longer duration necessitates taking one or more of the following precautions:
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and subsequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and subsequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
14. The method according to claim 1 wherein a spark-over oc-curring between pulses and causing voltage drop of short dura-tion necessitates taking one or more of the following precau-tions:
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and sub-sequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subse-quently raising it; and D) increasing the finger voltage in a DC-voltage control-ler using a periodically occurring finger of increased voltage.
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and sub-sequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subse-quently raising it; and D) increasing the finger voltage in a DC-voltage control-ler using a periodically occurring finger of increased voltage.
15. The method according to claim 2 wherein a spark-over oc-curring between pulses and causing voltage drop of short dura-tion necessitates taking one or more of the following precau-tions:
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and sub-sequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and sub-sequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
16. The method according to claim 3 wherein a spark-over occurring between pulses and causing voltage drop of short duration necessitates taking one or more of the following precautions:
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and subsequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
A) reducing the DC-level by a predetermined amount if the type spark-over rate is over a pre-selected set value, and subsequently raising it;
B) reducing the pulse repetition frequency by a certain pre-selected amount and subsequently raising it;
C) reducing the pre-set value for the precipitator corona discharge current by a certain predetermined amount and subsequently raising it; and D) increasing the finger voltage in a DC-voltage controller using a periodically occurring finger of increased voltage.
17. The method according to claim 1 wherein only the pulse voltage is turned off in response to a spark-over occuring between pulses and causing voltage drop of short duration.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8040463 | 1980-12-17 | ||
| GB80.40463 | 1980-12-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1172687A true CA1172687A (en) | 1984-08-14 |
Family
ID=10518049
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000392279A Expired CA1172686A (en) | 1980-12-17 | 1981-12-15 | Method of controlling operation of an electrostatic precipitator |
| CA000392290A Expired CA1172687A (en) | 1980-12-17 | 1981-12-15 | Method of controlling operation of an electrostatic precipitator |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000392279A Expired CA1172686A (en) | 1980-12-17 | 1981-12-15 | Method of controlling operation of an electrostatic precipitator |
Country Status (13)
| Country | Link |
|---|---|
| US (2) | US4445911A (en) |
| EP (2) | EP0054378B2 (en) |
| JP (2) | JPS57127462A (en) |
| AU (2) | AU547654B2 (en) |
| BR (2) | BR8108193A (en) |
| CA (2) | CA1172686A (en) |
| DE (2) | DE3165590D1 (en) |
| DK (2) | DK158377C (en) |
| ES (2) | ES8303121A1 (en) |
| IE (2) | IE52163B1 (en) |
| IN (2) | IN155609B (en) |
| NO (2) | NO814276L (en) |
| ZA (2) | ZA818630B (en) |
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-
1981
- 1981-12-02 EP EP81305677A patent/EP0054378B2/en not_active Expired - Lifetime
- 1981-12-02 DE DE8181305678T patent/DE3165590D1/en not_active Expired
- 1981-12-02 EP EP81305678A patent/EP0055525B1/en not_active Expired
- 1981-12-02 DE DE8181305677T patent/DE3169116D1/en not_active Expired
- 1981-12-07 DK DK539081A patent/DK158377C/en active
- 1981-12-07 AU AU78334/81A patent/AU547654B2/en not_active Ceased
- 1981-12-07 DK DK538981A patent/DK165050C/en not_active IP Right Cessation
- 1981-12-08 IE IE2883/81A patent/IE52163B1/en unknown
- 1981-12-08 IE IE2882/81A patent/IE52162B1/en unknown
- 1981-12-11 ZA ZA818630A patent/ZA818630B/en unknown
- 1981-12-11 ZA ZA818629A patent/ZA818629B/en unknown
- 1981-12-15 NO NO814276A patent/NO814276L/en unknown
- 1981-12-15 CA CA000392279A patent/CA1172686A/en not_active Expired
- 1981-12-15 US US06/331,012 patent/US4445911A/en not_active Expired - Lifetime
- 1981-12-15 NO NO814274A patent/NO814274L/en unknown
- 1981-12-15 CA CA000392290A patent/CA1172687A/en not_active Expired
- 1981-12-16 BR BR8108193A patent/BR8108193A/en unknown
- 1981-12-16 ES ES508028A patent/ES8303121A1/en not_active Expired
- 1981-12-16 BR BR8108195A patent/BR8108195A/en unknown
- 1981-12-16 AU AU78567/81A patent/AU550175B2/en not_active Expired - Fee Related
- 1981-12-16 ES ES508027A patent/ES8303120A1/en not_active Expired
- 1981-12-17 IN IN1428/CAL/81A patent/IN155609B/en unknown
- 1981-12-17 JP JP56204487A patent/JPS57127462A/en active Pending
- 1981-12-17 IN IN1427/CAL/81A patent/IN155698B/en unknown
- 1981-12-17 JP JP56204486A patent/JPS57127461A/en active Pending
-
1984
- 1984-04-30 US US06/605,180 patent/US4659342A/en not_active Expired - Lifetime
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| MKEC | Expiry (correction) | ||
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Effective date: 20011215 |