DE2608436A1 - ELECTROSTATIC SEPARATOR ARRANGEMENT - Google Patents

Description

U-in _:. Carpenter

^ · '- ;. V. V / C ■ · ■ «! · 'Ti

'■■■' ■■ - ·

March 1, 1976

EElA-Ii ndberg A / S
Ballerup, Denmark

The invention relates to an electrostatic arrangement From divorce, comprising a voltage source from which the impulses are fed to the electrodes of the separator, which one rectified voltage are superimposed, so that the electrostatic Separator for precipitating heavily resistive Dust particles is particularly suitable.

The Liethode of applying a periodically variable Voltage to electrostatic precipitator is in the application Separator sy stars with two electrodes or with three electrodes known per se, but this method has not yet been able to establish itself to a broader extent because of the voltage sources of known type do not meet the power and energy requirements for repeated charging of the electrostatic precipitator could.

609838/0640

For the inventive electrostatic precipitator of the mentioned type, it is characteristic that the electrical circuit of the separator Liittel for picking up the during the impulse of the 8 voltage source encompasses the effect stored in the separator.

This energy recovery results in a reduction the energy and power consumption that is required, to charge the electrical capacitor that the electrostatic one Represents separator.

Iri_e electrostatic operated with a pulse voltage First and foremost, separators are beneficial in the following ways:

The particles are charged better because the peak value of the voltage can be increased without the voltage mean value and thus to increase the number of flashovers. By reducing the Pulse amplitude and the pulse frequency make it possible to control the emission current to be controlled independently of the main electrical field, so that the current load of the dust layer on the precipitation electrode can be adjusted to the re-posting limit for which the the specific resistance of the dust is decisive.

The uneven distribution of electricity in the conventional Separation entails re-emission or whirling up, when the precipitated dust is heavily resistive. at Use of pulsed voltage operated three-electrode separators a very even current distribution over the precipitation electrode can be achieved can be achieved if one works with extremely short voltage surges of high Au.plitu.de, because this is an electron cloud of high charge density and therefore high expansion force can deliver. This results in a better distribution of the from each individual emission electrode generated emission current via the precipitation electrode brought about.

With conventional electrostatic precipitators it is As is well known, there is also the problem that a fraction of a few percent of the i.bscheidervolens due to different gas conditions or due to the return conditions inside the separator almost 100 percent of the separator flow

609838/0640

know Barch application of impulses can be independent ^ i ^. from the local Gas and re-emission ratios ensure an even distribution over the entire area i de rte il can be achieved because for the emission current the work function for impulses of short pawn and high amplitude is decisive in the release of the charge carriers from the emission electrode. ! This depends on the Emission electrode from, but only a little of the surrounding gas.

A Zweielektro de near separator can operate in electrical Considered as the equivalent of a capacitor to which a resistor is connected in parallel or in series is, and the energy supplied to the separator can therefore be divided into an active and a blind part. The feed of 7, 'irkenergie is an irreversible gate passage while the feed of reactive energy can be viewed as a reversible process. at The methods known up to now, however, were a recovery of the energy in the capacity of an electrostatic precipitator during the pulse duration stored considerable energy is not possible, but rather this energy was instead converted into waste heat.

This unnecessary expenditure of energy can be omitted quantitatively Calculate the formula (l).

where G = capacity

Vp = peak voltage
T = initial voltage.

The corresponding performance can be calculated using formula (2).

Q. = V E (2)

where ri π £ = 'I mpul s fo 1 ge f re que η ζ,

The following are some examples of the calculated Energy and performance expenditure for different capacities and Voltage values listed ι

Tabel

'J. · ■ ·; 'i ^! i / Ü 'j' ι 0

Table la
(Two Ie ctro de nsy ste α.) 2 - 3 4th 1 150 70 15C C. XiF 7C 50 50 50 7 " kV 5C 20th
18C 100
700 100
1500 V
P.
egg kV 20
Joule 8 5 75 280 6C0 Q k ¥ 35

G = capacity of the separator

V = DC voltage

V = superimposed pulse voltage

iü = energy consumption, for single charging

Q = power requirement (with a pulse repetition frequency of 400 Hz).

Table Ib
(Dreie le ktro de η sj s te m)

⁰ bra nF 100 160 160 I6O I60 ^α ϋΐυ ELEVEN 30th 80 80 80 80 ^v hu kV 50 50 50 50 50 ¹⁷ ETT kV 50 50 50 50 30th ⁷ P kV 50 20th 50 100 50 SL J 240 130 500 I6OO 66O Q k ¥ 95 50 200 640 265

L-r, = capacitance emission electrode - auxiliary electrode

£ iB.

_x ,. = capacity emission electrode-median impact element-

trode

V = DC voltage between auxiliary and precipitation

St.

electrode

V __ = DC voltage between emission and precipitation electrode

V - superimposed pulse voltage E = energy consumption, for individual charging

Q = power requirement (with a pulse repetition frequency of 400 Hz).

As

609838 / 06A0

π _

As can be seen from the facts, the power requirement of large separators (with a leather-impact electrode surface of more than 25C0 π) "at high impulse voltages reaches 7 / erts of 2CO" to 600 k ¥. Since this performance · be used in a conventional separator only 10 percent, it is obvious that the Icipulsbetrieb electrostatic precipitator la-scale hatred rod can not be considered for reasons of Y. "irtscliaf ti i cake it, if the energy of egg η ze 1 impulse is not efficiently recovered.

In addition to reducing energy consumption, the Invention also the safe deletion of the Ko ro nae η ti a fertilize η after each Pulse.

To influence the charging current and with the three-electrode system also, the current distribution over the collecting electrode one must actually be able to determine the time function of the corona flow to influence. The Lmissionsstrom depends not only on that Instantaneous value of the separator voltage, but also whether of an ionized plasma is present from the outset in the immediate vicinity of the emission electrode, since in this case the tendency to New ionization is increased, so that at a relatively low: field strength new charge carriers are formed. It is therefore for the invention further identifying, daj? a deletion of the corona discharge short-term reduction of the stress below the value of the main stress can be ensured after each pulse.

In a preferred embodiment of the invention the means for recovering the pulse energy comprises an LC resonant circuit, which includes the separator as a capacitive element and which also contains a storage capacitor, a pulse of oxygen the one direction of flow and an electrical valve arrangement of the opposite direction of flow are included.

With each pulse, energy is supplied to the electrostatic separator from the storage capacitor, which serves as an energy reservoir, via the pulse sau si ösungsmi tte 1, which can be, for example, a thyristor, a thyristor combination or a spark gap the valve arrangement, for example a diode or diode combination, back to the storage

cher capacitor

609838 / 06A0

- 6 cher capacitor closes.

The invention will now be based on the details attached drawings are described. Show in it:

Fig. 1 is a circuit diagram of a pulse gener a to rs for the Operation of an electrostatic precipitator according to a first embodiment Guide to the invention,

Jig. 2 a scarf cheraa of an impulse gener a to rs for the Operation of an electrostatic precipitator according to a second embodiment the invention;

Fig. 3 is a Schaltscheiia a pulse generator for the Operation of an electrostatic precipitator according to a third embodiment the invention;*

Pig. 4 sin circuit diagram of a pulse generator for the Operation of an electrostatic precipitator according to a fourth embodiment rungsf ο rm of the invention,

Fig. 5 is a circuit diagram of a pulse generator for the Operation of an electrostatic precipitator according to a fifth embodiment, the invention », and

Fig. 6 is a circuit diagram of a pulse generator for the Operation of an electrostatic precipitator according to a sixth embodiment the invention.

In the illustration of FIG. 1, the reference number 1 denotes a charging circuit for a storage capacitor 7, and with the reference number 2 a discharge circuit in which the pulses are generated, the part 2 in combination with the üteil 3 that circuit represents in which they oscillate.

From a single-phase or multi-phase voltage source 4 a single or multi-phase alternating voltage is obtained, which by means of a rectifier 5 (which is, for example, a Sin-phase or Mährphasen bridge coupling can act) rectified will. A coil 6 separates the DC voltage source from the switch-on surges resulting from the pulse generator but the direct current supply of an electrode combination 16, the

Emission electrode

609838/0640

! emission electrode and the j ± c de rschlagselektro de of an electrostatic precipitator, "for example a precipitator of the" known type, used as a gas filter for precipitating dust particles from a gas flow ". The number 7" denotes a capacitor, from de ε the energy for the impulses is taken and then fed back! To start the generator and to compensate for the "energy consumed in the corona discharge on the one hand and in the form of losses in the components and conductors on the other hand with each pulse." new line energy can be fed to the capacitor. This is done via a current limiting resistor 8 and a coil 9. Reference number 10 denotes a thyristor which can be switched on with the aid of a circuit (not shown). If this is the i'sll, the charge of the capacitor 7 oscillates and goes over a Lrpul sub he carrier 12 ::. ± a primary winding 13 and a secondary winding 14 a capacitor 15 as well as the cell electrode combination l6 and then over a diode (or diode combination ) 11 with the opposite conduction direction to that of the [thyristor back to the capacitor ¹ J. The period of oscillation is determined by the short-circuit inductance of the pulse transformer 12 and the capacitance values of the capacitors 7 and 15 as well as by the capacitance value of the electrode combination l6. The capacitor 15 is included in the generator so that no direct current flows through the secondary winding 14 of the pulse transformer 12, and its capacitance must be in such a ratio to that of the electrostatic precipitator 16 that the pulse voltage amplitude in an appropriate proportion between the two capacitances is divided.

In I'ig. 1 is also the use of circuit 1 for supply Another electrode combination 17 is shown, which the auxiliary electrode and the Hie de rschlagselektro de of a three-electrode separator can represent, see Pig. 5 ·

In Fig. 2, the reference numeral 20 is a charging circuit for denotes a capacitor 25 and numeral 21 denotes a discharge Circuit in which the pulses are generated, part 21 in combination with a part 22 represents that circuit in which. the pulses oscillate.

60 9 838/0640

Bio reference number 23 denotes a high voltage 3 light current source, the positive connection of which is grounded _r so that a negative voltage can be drawn from this voltage source. i, a coil 24 separates the voltage source 2J from the switch-on surges which originate from the inculse generator. Lit the reference number 25 denotes a capacitor from which the energy for the pulses is taken and to which it is then supplied again. To start the generator and to compensate for the energy consumed with each pulse on the one hand in the Ko ro nae η ti a dung and on the other in the form of losses in the components and conductors, the capacitor must be supplied with new energy. This energy is obtained from a charging circuit consisting of a current limiting resistor 26 and a coil 27. Located in one between two spark electrodes 34 and. 35 formed Funice ns track 28 a flashover takes place, so the charge of the capacitor 25 oscillates and goes over the spark gap 28 and a coil 32 to a capacitor 31 and an electrode combination 33 representing an electrostatic precipitator and then via a diode (or diode combination) 29 again dent Capacitor 25 closed. The flashover in the spark gap 28 can either be brought about by setting the spark gap to self-ignition at a predetermined threshold voltage, or by controlling the spark gap in one form or another, for example by irradiating the spark gap with ultraviolet light. If the spark η segment ignites by itself, the oscillation process must be damped so strongly that the spark gap does not ignite again after the pulse voltage to the capacitor 25 oscillates back. In a spark gap of this type, the time constant of the charging circuit 26, 27 and the capacitor 25 is decisive for the pulse train frequency. A coil 30 serves to keep one side of the spark gap grounded in terms of direct current, but separated from ground at sufficiently high frequencies. The capacitor 31 is included in the generator so that no direct current flows through the coil 30 from the direct current source, and its capacitance must be in such a ratio to that of the electrostatic precipitator 33 that the pulse s voltage amplitude in an appropriate proportion between the two capacities is divided · The duration of the through

609838/0640

the rollover in the spark gap 28 generated oscillation due to the inductance of the coil J2 «nö the capacitance values of the capacitors 25 ttnd 31 as well as by the espacite value of the electrostatic precipitator 53 is determined.

In Fig. 3 ", the reference number 40 denotes a high-voltage direct current source, the positive connection of which is grounded so that a negative voltage can be drawn from the voltage source. It thus determines the average voltage across the electrostatic precipitator. The coil 4I serves to separate the voltage sources 40 from any external surges resulting from the generation of pulses. BLe reference number 43 denotes a capacitor from which the energy for the pulses is drawn and they wird- fed back is contrast to by the circuits of FIGS. 1 and 2 pulse generators formed. pulse generation 3 takes place is Pail the arrangement of FIG. independently of the GleichstroBversorgung of the separator 51. In the circuit of Fig. 3 A separate direct current source 42 is used to charge a storage capacitor 43 in the Star of the generator and when balancing out the one part consumed in the corona discharge and the other part in the form of losses in the components η nnä conductors. Energy. The positive connection of the voltage source 42 is grounded so that a negative voltage can be generated from the voltage source. Mne coil 44 serves to ^{limit the current flowing to capacitor 43 a} * is of direct current source 42 (current rise) as well as to run away from the voltage source from the bit-switching surges resulting from the generation of pulses. If a Tb jristorkombimatlon 45 is switched on, then the charge of the capacitor oscillates 43 ^ ad passes through an Isroulstransfer 4? with a primary winding 48 and a backing 49 iron capacitor 50 and the separator 51 ^ttIi -ä thereupon via a mode combination 46 iai * opposite direction to that of the hiyristor part combination of the capacitor 43. Me oscillation duration udrd torch dde short-circuit inductance of the pulse transformer 47 ΐ £ && the capacitance values of the capacitors. 43 and 50 as well as determined by the capacitance value of the separator 51.

809838/0640

- IG -

Ler: roüder, sater JQ is in the. '-Bnerator einbesoss so that through-the Seivuadl'rwicklung- 49 5ES Ispul Suebe r rs wear flows 47 SISS DC, vmä its capacity iau £ to that of the separator ^ I in such a ratio are, dai3 the Impulsspannungsanplltude between the two capacitances in is divided into an appropriate proportion.

In FIg. 4, the reference numeral 6o denotes a pulse generator, for example the one described in connection with FIG. 2 or 3. Tile from the graphical figure ₇ , the pulse generator 6o is connected to a direct current source 6l and the emission electrode 63 of an electrostatic precipitator 62 and can either be self-sufficient, as shown in IPIg-. 2 is gezelg-t, or he can never In FIg. 3 require a separate supply. Ba 6 & X positive terminal of the DC power source zusarimen with precipitation electrode 64 de s precipitator grounded 1st billion applied to the Lialsslonselektrode a negative voltage.

In Fig ". 5, reference numeral 70 denotes a pulse generator, such as the. As described in Sesugnshnie on SLg. 1 from the Darstellung- apparent, the pulse generator 1st 70th between a DC power source 71 and the emission electrode 73 of an electrostatic precipitator 72 set and can be either be self-sufficient, it id.e in Fig. 1, or may require a separate power supply. Bine auxiliary electrode 74 äes separator 72 1st connected directly to the SLeIchStromquelle TI and the potential difference between the auxiliary electrode ä 74 ^aQ. the emitting electrode 73 therefore stasmt of the pulse voltage. Since the negative terminal of the SLe I current source is grounded together with the deposition electrode 75 of the separator, the emission will also me DER auxiliary electrode positive voltages supplied.

In FIG. 6, the Bezugszafctl 80 denotes a pulse generator, such as the ± ii Fig. 2 or 3 shown. As can be seen from the drawing, the pulse generator BO is placed between a SIeIchstromquelle 81 and the emission electrode 83 of an electrostatic precipitator 82 and can either be self-sufficient, never this in FIg *. 2, or as in FIG

609838/0640

Fig. 3 require a separate feed. The separator also has an auxiliary electrode 84, which is connected to a separate direct current source 86 is connected, and the photential difference between the auxiliary electrode 84 and the irJLssionsel & ctrode SJ are therefore the same the impulse voltage superimposed on a DC voltage. Because the positive Connections of the two direct current sources together with the precipitation electrode 85 of the separator are grounded, negs, tive Voltages on the emission electrode as well as on the auxiliary electrode created.

The examples described above with reference to the drawings serve only to illustrate the invention and are in no way to be construed in a limiting sense of the invention.

By suitable measures it can be achieved that the Pulse generators described above to supply several Separator parts can be used, so that in the case of one a single electrostatic precipitator divided into sections A pulse generator is sufficient.

Claims

609838/0640

Claims (4)

P - ^! --- te r. ta η s ρ rüche \ 1 / .le: ctrostatische separator assembly comprising a voltage sensors ■ -aerator for supplying a rectified voltage superimposed pulses to the .Elektroden of the separator, characterized by the Li: ib ^ ζ ie hung from iätteln (ζ, 3) to the return line · The predecessor of each pulse of the voltage generator (2) in the separator (l6) stored effect in the electrical circuit arrangement of the separator (lo). 2. electrostatic reticle! The ra.ncrdnun ~ according to claim 1, characterized in that the said means comprise an LC resonant circuit (2, 3) which includes the separator ^ 1.6) as a capacitive element and which also has a storage capacitor (7) 5 ^e in pulse triggering means ( lO) which engages in a direction of flow and an electrical valve assembly (11) with an opposite direction of flow. 5 · ..- Ioctrostatic separation of the arrangement according to one of claims 1 and 2, characterized by the fact that the self-induction of the LC-öchv / ingiireise s (2, 5) through the secondary winding (I4) of a pulse transmitter (12) is formed 4. electrostatic separator arrangement according to one of claims 1 and 2. characterized in that the self-induction of the LC-Sehvri-ngkreise s (21, 22) by a series connection of z; yei self-induction coils formed, one of which in the store ladder of the separator (33) is placed, while the other is a self stxnduktions coil, which is connected in series with a Spark gap (28) and a voltage source shunted is. 5 · Electrostatic separator arrangement after one of the preceding ones Claims, characterized in that the LC resonant circuit on Eesonanz is tuned at a frequency that approximates the pulse than Ealbwelle has. ü 0 9 6 3 8/0 G 4 0