EP0162826B1 - A device for additional cleaning of dustladen medium, which to some extent has already been cleaned in an electrostatic presipitator - Google Patents

A device for additional cleaning of dustladen medium, which to some extent has already been cleaned in an electrostatic presipitator Download PDF

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Publication number
EP0162826B1
EP0162826B1 EP85850175A EP85850175A EP0162826B1 EP 0162826 B1 EP0162826 B1 EP 0162826B1 EP 85850175 A EP85850175 A EP 85850175A EP 85850175 A EP85850175 A EP 85850175A EP 0162826 B1 EP0162826 B1 EP 0162826B1
Authority
EP
European Patent Office
Prior art keywords
medium
outlet
precipitator
cleansed
dustladen
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
Application number
EP85850175A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0162826A1 (en
Inventor
Jan-Mats Eneroth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Technology FLB AB
Original Assignee
Flaekt AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Flaekt AB filed Critical Flaekt AB
Priority to AT85850175T priority Critical patent/ATE31880T1/de
Publication of EP0162826A1 publication Critical patent/EP0162826A1/en
Application granted granted Critical
Publication of EP0162826B1 publication Critical patent/EP0162826B1/en
Expired legal-status Critical Current

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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
    • B03C3/88—Cleaning-out collected particles
    • 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
    • B03C3/019—Post-treatment of gases

Definitions

  • the present invention relates in particular to an apparatus as stated in the preamble of claim 1.
  • means are provided which enable part of the medium cleansed in the precipitator to be recycled therein and/or further cleansed in a separate cleaning device herefor, preferably a separate filter.
  • the medium cleansed in an electrostatic precipitator will stratify as it leaves the precipitator and passes through an outlet connected thereto, therewith to form different flow layers or layers of varying dust concentration, in which the layer containing the most dust is located in the lowermost parts of the outlet, while layers of lower dust concentration become oriented above this lowermost layer, and consequently the layer located in the uppermost part of the outlet will have a low dust concentration.
  • one technical problem is of providing conditions which enable said further cleansing of the partially cleansed dustladen medium to be carried out during those periods of time and during such periods as those at which particularly high dust concentrations can be expected or are present.
  • a further technical problem is one of providing conditions which enable as little of the medium cleansed in the precipitator to be re-cycled therein, thereby to increase the efficiency of the precipitator, or to be supplied to a separate filter.
  • Another technical problem in this art is one of providing conditions which enable emission to be decreased or minimized by cleansing and handling in a separate or special cleansing device, preferably a separate filter, as small a percentate of high dust concentration as possible of the medium cleansed in the precipitator.
  • Another technical problem in this respect is one of providing conditions such that when the dustladen medium cleansed in the precipitator stratifies, in simple fashion, in an outlet connected to the precipitator, a layer of high dust concentration can be separated, with the aid of simple means, from a layer of lower dust concentration, so that the percentage of medium removed from the outlet has truly a high concentration of dust.
  • Another technical problem is one of enabling in existing plants further cleansing of a medium which has already undergone a cleansing process, with the aid of simple means.
  • a further technical problem in this art is to provide conditions such that the measures taken will not adversely affect the aerodynamic properties of the precipitator.
  • a still more complicated technical problem is one of providing conditions which enable a medium containing large quantities of dust to be taken-out discontinuously, normally periodically, and then only during those time durations when high dust concentrations are present and/or can be expected to occur.
  • the present invention now provides an apparatus which enables further cleansing of a dustladen medium which has already been cleansed to some extent in an electrostatic precipitator as stated in the preamble of claim 1.
  • the invention is particularly suited for application in those electrostatic precipitators provided with a tapering outlet section.
  • arranged in the upwardly sloping lower part of the outlet section, as seen in the direction of flow is one or more openable outlets, which enable a percentage of partially cleansed medium to be taken-out through the outlet discontinuously over those time periods in which high dust concentrations prevail and/or are to be expected.
  • the percentage of medium removed is suitably at most 10% of the total flow of medium passing through the outlet, preferably at most 5%.
  • the outlet located adjacent this electrode is caused to open in response thereto.
  • This opening of the outlet may be delayed for a time period equal to, or slightly less than the time taken for the particles to move from the rapped electrode to the openable outlet in question.
  • FIG 1 there is illustrated in perspective an embodiment of an electrostatic precipitating plant 1, comprising a plurality of mutually parallel chambers, each provided with four electrode groups.
  • Each of these electrode groups requires the provision of a transformer/rectifier unit.
  • the electrode groups are positioned so that the outlet of one group is connected directly to the inlet of a subsequent group, etc. Since the electrode group 2 of the illustrated embodiment constitutes the last group in the electrode-group array, the outlet of this group is connected to a chimney 4.
  • the illustrated precipitator is shown to comprise a plurality of electrode groups, there is nothing to prevent each electrode group from forming part of an individual electrostatic precipitator.
  • the electrostatic precipitator plant 1 is of the kind in which a dustladen medium is introduced to an inlet 5 and caused to pass into the first group of electrodes, this dustladen medium normally being dustladen air although, as will be understood, said medium may also comprise some other dustladen gas or gaseous mixture, and primarily dustladen flue gas.
  • this electrode group, and also other electrode groups the particles carried by the medium are electrically charged by the electric field generated by mutually ajacent collecting electrodes and emission electrodes arranged therebetween, by applying a high direct-current voltage to the emission or discharge electrodes.
  • a dust particle entering this field becomes negatively charged electrically and will then be attracted to the positive collector electrode and repelled by the negative discharge electrode, thereby causing a collection of particles to accumulate primarily on the collector electrodes.
  • the air progressively cleansed during its passage through the sequence of electrode groups then passes out through the outlet 5a and enters the chimney 4.
  • the medium cleansed in the precipitator is arranged to exit therefrom through a funnel- shaped outlet 6.
  • the dustladen medium will stratify in the outlet 6 to form layers of varying dust concentration, such that the concentration of dust in the lower part 7 is much higher than the dust concentration of layers located thereabove, while a layer located in the upper part 8 will have but low dust concentration.
  • the plates are rapped mechanically as soon as the dust coating thereon reaches a given thickness, this dust coating then falling down into the bottom part 2a of the precipitator.
  • This advantageous further cleansing of the medium is effected in accordance with the invention by recycling in the precipitator part of the medium cleansed therein and/or removing part of said medium and cleaning the same in a separate cleaning device herefor, preferably a separate filter.
  • the bottom part 6a of the outlet has connected thereto one or more pipes 10 which communicate with a respective pipe 12 through a fan means 11.
  • the pipe 12 can either be connected to the inlet 5 or to a location in the vicinity of said inlet.
  • the pipe 12 may be connected by means not shown to a filter, also not shown. This filter may advantageously comprise a separate low- capacity filter.
  • the pipe 10 is closed when the fan is stationary.
  • the percentage of medium removed is taken from a layer of relatively high dust concentration, and consequently the lower part of the exiting, partially cleansed medium is chosen for this purpose.
  • the fan 11 may be controlled by a control means 14, through a conductor 13, so that the removal of said medium takes place periodically and over time periods or durations at which high dust concentrations prevail and/or can be expected to occur.
  • the control means 14 can be controlled by a signal passed through a conductor 15 when mechanical rapping of the flat collector electrodes takes place, and the control means 14 may incorporate a delay circuit which, when activated, causes dustladen medium to be removed from the outlet throughout a predetermined period of time.
  • the speed at which the fan operates is controlled by the control means 14 in response to a signal sent by a known opacity meter 16 through a conductor 17, such that when the medium in the vicinity of the opacity meter 16 contains large quantities of dust the fan speed will increase, and will decrease when the dust concentrations in the vicinity of said meter are low, in response to applicable signals from said meter. This enables the dust concentration to be corrected or regulated.
  • control means 14 can be adapted to control the fan 11 in dependence on other parameters such as the dust concentration sensed in the inlet 5 for example in response to signals sent through a conductor 18 and to prepare for further cleansing of the dustladen medium leaving the precipitator through the outlet when the amount of dust contained by the medium entering the precipitator exceeds the separating capacity of the electrostatic precipitator.
  • control means 14 may suitably incorporate control funcitons which are effective to recycle the medium when conditions in the electrostatic precipitator are such as to enable further cleansing to be carried out, and which in the absence of such conditions cause this further cleansing of the medium to be effected in a separate filter.
  • Figure 3 illustrates in side view and in section an alternative outlet to the outlet illustrated in Figure 2, said alternative outlet being provided with means for enabling, in accordance with the invention, further cleansing of a partially cleansed dustladen medium.
  • this alternative outlet means Connected to the bottom part 6a of this alternative outlet means is a number of mutually adjacent hoppers 20, 21, 22, of which only one is shown in Figure 3. Located in the lower part of respective hoppers is a valve 23 through which medium containing large quantities of dust is allowed to pass. A discharge pipe 24, similar to the pipe 10 of the Figure 2 embodiment, is connected to the hopper, in the manner illustrated in Figure 2.
  • the electrostatic precipitator 1 is provided with a plurality of flat collector electrodes, of which only a few are shown, these electrodes being referenced 30, 30a, 30b and 31, 31 a, 31 b.
  • Those parts of the medium removed correspond at most to 10% of the total medium flow through the outlet, preferably at most 5%.
  • This part of said medium is preferably removed over a time duration of at most 5%.
  • Rapping of certain flat collector electrodes results in a layer in which dust concentration varies in the horizontal plane, and it is proposed that the aforesaid part of said medium is removed from that part or those parts in which a high dust concentration prevails and/or is expected to occur.
  • This part of the medium flow is advantageously removed through one or more of a plurality of openable and closeable outlets arranged in side-by-side relationship. These outlets may also be controlled by the control means 14.
  • the arrangement is such that when a flat collector electrode is rapped, the outlet located adjacent thereto is opened.
  • This opening of the outlet may be slightly delayed, suitably by a delay time slightly shorter than the time taken for the particles shaken from the electrode to move to the openable outlet.
  • control means of the Figure 2 embodiment may also have the form of the control means of the Figures 3 and 4 embodiments.
  • the flow rate of the dustladen medium through the precipitator is calculated by means not shown, and the relevant delay time between the rapping of respective flat collector electrodes and the opening of one or more outlets is calculated in the control means.

Landscapes

  • Electrostatic Separation (AREA)
  • Cleaning In General (AREA)
  • Ladders (AREA)
  • Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
EP85850175A 1984-05-17 1985-05-17 A device for additional cleaning of dustladen medium, which to some extent has already been cleaned in an electrostatic presipitator Expired EP0162826B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85850175T ATE31880T1 (de) 1984-05-17 1985-05-17 Vorrichtung zur komplettierenden reinigung eines staubgeladenen mediums, das schon in einem elektrostatischen staubabscheider zum teil gereinigt wurde.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8402658A SE8402658L (sv) 1984-05-17 1984-05-17 Anordning for att ytterligare rena ett i en elektrostatisk stoftavskiljare redan i viss man renat stoftbemengt medium
SE8402658 1984-05-17

Publications (2)

Publication Number Publication Date
EP0162826A1 EP0162826A1 (en) 1985-11-27
EP0162826B1 true EP0162826B1 (en) 1988-01-13

Family

ID=20355910

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85850175A Expired EP0162826B1 (en) 1984-05-17 1985-05-17 A device for additional cleaning of dustladen medium, which to some extent has already been cleaned in an electrostatic presipitator

Country Status (6)

Country Link
EP (1) EP0162826B1 (sv)
JP (1) JP2608872B2 (sv)
AT (1) ATE31880T1 (sv)
DE (1) DE3561375D1 (sv)
DK (1) DK163418C (sv)
SE (1) SE8402658L (sv)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3625547A1 (de) * 1986-07-29 1988-02-11 Walther & Cie Ag Elektrostatischer staubabscheider
JPS6354445U (sv) * 1986-09-26 1988-04-12
SE468628B (sv) * 1991-11-26 1993-02-22 Flaekt Ab Saett att reglera stroempulsmatningen till en elektrostatisk stoftavskiljare

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE314171C (sv) *
BE562091A (sv) * 1956-10-31
DE1457095A1 (de) * 1965-07-23 1969-10-16 Metallgesellschaft Ag Verfahren zur Erhoehung des Gesamtreinigungsgrades einer Sintergasentstaubungsanlage
JPS5036311A (sv) * 1973-08-04 1975-04-05
DE2441233C2 (de) * 1974-08-28 1983-02-03 Metallgesellschaft Ag, 6000 Frankfurt Elektrostatischer Staubabscheider
JPS5436674A (en) * 1977-08-29 1979-03-17 Daido Steel Co Ltd Electric dust collector
JPS5917392Y2 (ja) * 1979-07-03 1984-05-21 ガデリウス株式会社 電気集塵装置

Also Published As

Publication number Publication date
DK163418C (da) 1992-07-20
JP2608872B2 (ja) 1997-05-14
DK216785D0 (da) 1985-05-15
EP0162826A1 (en) 1985-11-27
DK163418B (da) 1992-03-02
JPS60255159A (ja) 1985-12-16
DE3561375D1 (en) 1988-02-18
DK216785A (da) 1985-11-18
SE8402658D0 (sv) 1984-05-17
ATE31880T1 (de) 1988-01-15
SE8402658L (sv) 1985-11-18

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