US1974226A - Fluid treater - Google Patents

Description

Sept, 18, 193 i 7 H. A. WINTERMUTE FLUID THEATER Filed May 11, 1953 2 Sheets-Sheet 1 wy MW 3 3 67mm,

Sept. 18, 1934. H, WINTERMUTE 1,974,226

FLUID THEATER Filed May 11, 1933 2 Sheets-Sheet 2 Patented Sept. 18, 1934 FLUID TREATEE Harry A.

to Research Corp ration,

Wintcrmutc', Plainfield, .N. 1., assignor New York, N. Y., a

corporation of New York Application May 11, 1933, Serial 'No. 670,558 18 Claims. (01. 183 -7) This invention relates to a new and improved electrical circuit; for operating fluid treaters such as electrical precipitators of the Cottrell type which are used in removing suspended particles from gases. It further relates to means for maintaining the circuit in satisiactory operating condition.

In particular the invention relates to a circuit for energizing opposing electrodes in a treater to a high potential difierence with impulses which have a very steep wave front and which remain at high potential for a very short interval of time, the circuit being so arranged as to include a a spark gap in parallel with a condenser, the condenser being characterized by having for a dielec tric the fiuid being treated between the opposing electrodes.

Electrical precipitators of the Cottrell type comprise a casing with inlet and outlet for the gases to be treated and two groups of opposing electrodes within the casing which are insulated from each other. In operation, the opposing electrodes are maintained at a high potential difierence, while the gases to be treated are passed through the strong electric fields thus created. It is common practice to have the electrodes of one group of relatively fiat contour, while the opposing electrodes are wires or chains which are insulated from the fiat electrodes and maintained at high potential diiierence from them. The flat electrodes are termed'collecting electrodes because most of the sutpended material-removed from the gases collects upon them. The wire Y electrodes, or other electrodes of small cross section, are called discharge electric field in their immediate vicinity is very intense and corona discharges" emanate from their surface. The gases are subjected to electronic bombardment as they pass through the strong electric fields and become ionized. The

free electrons and ions moving under the force of the electric fields become attached to, and are instrumental in removing, the suspended particles in the gases.

It is common practice to energize the electrodes with a circuit comprising a high potential transformer and a mechanical rectifying switch; sometimes one or more thermionic tube rectifiers are used. The shapes of the current waves or impulses when using such rectifiers follow, in general, the sine wave of the primary current source, but are influenced by the capacity of the treater, the number and nature of the spark gaps in the rectifier circuit and other conditions. posing electrodes are usually charged to a maximum potential difference which is just below the value which will initiate spark-over and a potentialdifierence approaching this maximum value is maintained for an appreciable part of the energizing cycle.

electrodes because the The op- Now it has been found that advantages are obtained through the use of a circuit which includes a spark gap in parallel with a condenser whereby an impulse with a steep wave front is impressed upon theelectrodes at every break down of the spark gap. One of the advantages noted is that the peak or maximum potential of such an impulse, which is of short duration, can be 15 to 30% higher than the peak potential of an impulse which is of appreciable duration. This higher voltage results in more intense ionization of the gases. Moreover, in the treating of hot dry gases an undesirable back corona condition is less liable to exist with impulses of short duration.

The present invention makes it possible to secure the advantage of steep front impulses of short duration. It also makes it possible to construct a section of a treater as a non-ionizing zone,

without discharge electrodes, for collecting particles which have been electrically charged in the ionizing zones, but have passed through these zones without collection.

The principal object of the invention is to provide a circuit with which the electrodes of an electric treater can be energized with steep wave front impulses and which includes as a part of the circuit a-condenser within the treater to impart to the impulses the desired characteristics.

Other objects of the invention are: to have the plates of the condenser constitute portions of the collecting electrode surfaces within the treater; to secure the advantages of a treater with alter nate ionizing and non-ionizing zones of treatment; to provide a circuit which permits of either half wave energization or full wave energization; to provide adjustable means whereby the characteristics of the impulses can be altered; to accomplish a substantially even and efllcient distrodes within the treater; and to provide means for keeping the electrodes free from excessive deposits or material which would tend to change the characteristics of the circuit.

The manner in which the objects of the inven- I tion can be realized will be illustrated with the accompanying drawings, in which: I

Fig. 1 shows more or less diagrammatically the electric circuit including a treater in sectional elevation;

Fig. 2 shows a plan partly in section of the treater shown in Fig. 1;

Fig. 3 is a fragmentary view of a portion of th treater shown in Figs. 1 and 2; and

Fig. 4 is a diagram showing certain alternative arrangements of the connections shown in Fig. 1.

In Fig. 1 the low voltage supply circuit designated by numeral 1 is shown as a three-phase circuit, although two phase and even single phase can be used. The low voltage circuit 1, controlled phase branch circuit 12, taken'ofl two wires bfcircuit 1. Switch 13 and ohmic resistance 14 permit this circuit to be suitably controlled. Rectifying switch 4 is of the familiar type wherein the rotor comprises four insulating arms 8 with metallic tips 'I which support two jumper wires 8. When this rotor is revolved in synchronism with the current supplied through transformer 15, for example, at 1800 R. P. M. for 60 cycle current, all half waves of electrical energy of onepolarity alternately impressed upon first one and then the other of shoes 9 are directed to the adjacent shoe 10 which is connected to conductor it. Similarly all half waves of electrical energy of opposite polarity are directed to the other stationary shoe 10 which is connected to conductor 17. Conductor 16 is connected through conductors 18, 19 and 20 to a condenser 22, to be later described, which temporarily stores the electrical energy which is supplied by transformer it. Conductor it is also connected to switch 5 which revolves in synchronism with the hall waves and distributes them to the precipitator units as desired after they are given the desired steep wave front characteristic by the condenser. Switch 5 also functions as a spark gap for ma and bre the circuit in a manner conducive to the building up of impulses having steep wave fronts. The resce 18, which may include reactance, is for protecting switch a and transformer 15 from the high frequency oscillations occurring periodic l l in con= ductor 20. It is shown as having a variable ohmic resistance which permits it to be used in controlthe voltage in that part of the circuit including the condenser and preclpitator units.

The gas treater is included in casing 30 which has inlet 31 and outlet 32. It includes two units of the usual plate type which are marked 33a and 33b. These comprise collecting electrode plates 34 and discharge electrodes 35. Intermediate the treater units 3311 and 33b is a condenser unit 28 which is made up of plates 38 and rods 37. The rods 37 are of appreciable diameter as compared with the wires or edges which makeup discharge electrodes 35, because it is desirable that no corona discharges emanate from these rods and pet electrical energy temporarily held by the unit to leak away. Unit 28 functions, therefore, as a condenser with a gaseous dielectric and in the present circuit it is used for temporarily storing the electric impulses that energize the ionizing It functions also as an electrical precipitator of the non-ionizing type and removes from the gases passing through it those particles which carry free electric charges I of appreciable magnitude.

The circuit is completed by means of conductor 17 which connects shoe 10 with casing 30 of the gas treater. The casing is in mechanical and electrical connection with the various collecting electrodes. This side of the circuit is usually grounded as shown at 61.

In the operation of the circuit, a half wave of electrical energy from transformer 15, say of negative polarity, is directed by switch 4 to conductor 16 and reaches unit 28 through conductors 19 and 20. rotor of switch 5 assumes a position which will permit the passage of current from conductor 20 to conductor 21 through switch shoe 2o, jumper 8 and shoe 21'. This impulse rapidly built up (or This energy is released when therebuilt) by the release of the energy stored in condenser 28, through the two air gaps on switch 5 which are included in the circuit between conductors 20 and 21, has a very steep wave front, and when this is impressed upon the electrodes of treater 33b, the gases passing through that treater become highly ionized. A half cycle later when the rotor of switch 5 has revolved mechanical degrees, condenser 28, which in the meanwhile hasabsorbed another half cycle of electrical energy of negative polarity supplied by transformer 15, will be again discharged and this impulse will pass through shoe 22' and conductor 22 to unit 33a. If the units 33a and 33b are alternately energized as indicated. the result will be a saving in energy, although the precipitating efficiency of the units may be slightly less than ii? every impulse was sent to each unit. The latter condition may be obtained by inserting a jumper wire 23 between shoe 20' and an added shoe 2%. with this conductor added to the circult every impulse passing through conductor 16 and temporarily stored up in condenser 28 will be used in energizing both of the units 33a and 23b, The same result may be obtained by inserting a k gap'in place of switch 5. Fig. 4 shows such a circuit with spark gap 52 taking the place of-the rotating gaps of switch 5. F

it has been found advisable, in operating the equipment just described and in using the high wave front impulses that result from it, to design the equipment with consideration of the characteristics of this type of impulse. It has been found advantageous to eliminate sharp turns in the conductors as far as possible, and where air tion has been used it has been increased over con practice for sine wave current to prevent corona losses. It has also been found advantageous to insert choke coils in parallel circuits in order to obtain a better distribution of the energy in the various conductors. The mannor of using these choke coils is shown in Fig. 1 where coils 25 lightly check the rush of current as it leaves the inlet conductor 24 and divides in order to energize discharge electrodes 35 from th top and bottom. Mounted near the top of each discharge electrode is a small choke coil 26 which may be of one or more turns, but preferably I is a very simple air choke of few turns which is not appreciably affected by dust falling upon it and which retards only high frequency or very steep wavefront oscillations. Similar coils are provided at the bottom of the discharge electrodes as shown at 27.

' Asis well known, the electrical characteristics of electrodes change when they become covered with-material removed from the gases. This is particularly true when the material is of a nonconducting nature or is a heterogeneous mixture of particles having different electrical characteristics. -It is desirable that the electrodes of the precipitator shown in the figures be kept clean in order that the emciency of the precipitator be maintained and because certain of the electrodes-thou designated as 36 and 37-con.- stitute a condenser which is a vital part of the electric circuit and must be kept free of precipitated material if the condenser is to have a constant capacitance. It is important, therefore, that eillcient cleaning means be provided to maintain the electrodes free from the precipitated material. Referring to Fig. 1, the discharge electrodes are suspended from a central vertical support 38 which depends from and passes through an insulating chamber 39 which may be of insulating terra-cotta of considerable mechanical strength. The enlarged upper end of support 38 is mounted on a spring 40 which in turn rests on a substantial plate 41, which may be of metal, on top of chamber 39. A hammer mechanism 42 is periodically raised and dropped to impart blows to the support 38 and this causes a jarring of electrodes 35 which effectively removes any material that may collect upon them. The collecting plates 34 of units 33a and 33b depend from transverse members 43 which are positioned transversely in casing 30 and are supported at the sides of that casing. While these electrodes are adequately supported and spaced by members 43, they are free to vibrate when rapped. Near the lower ends of the electrodes, where movement of the same is more readily possible, transverse rapping means are provided. The rapping means may be at or near the bottom of the electrodes, as shown in Fig. l, and may consist of stiif members 44 upon which are held rigidly the hammer'means 45 shown in Fig. 3. The electrode surfaces, where the hammers 44 strike, are reinforced by stiffening plates 46. The

' a detrimental degree.

distanced between the faces of opposing ham- 1 mer means is slightly greater, for example than the thickness of a plate 34 with two reinforcing plates 46 upon it. It then a member 44 can be made torapidly move back and forth transversely of the plates, the plates will receive a jarring which will effectively dislodge'deposits of dust and the like that are clinging to it. This movement of members 44 isaccompli'shed by securing them to eccentric straps47 which in turn ride on eccentrics 48 on revolving shaft 49 which is revolved by motor 50 through reduction gear 51. It has been found beneficial to make the movement of the eccentric slightly greater than the distance between the faces of the hammer members. For example, if member 44 is moved of an inch and if the distance the hammer can move before striking plate 46 is only the hammer means will have to move the plate A; after striking it. This insures a positive striking and jarring of the plates by the hammer means on rods 44.

When only a few light plates are to be jarred a single member 44 will jar the rods without detrimental effect to the precipitator structure generally, but when the plates are large, especially when there are many of them in parallel across the casing of the precipitator, it has been found that to'hit all the plates on one side simultaneously not only requires considerable 'power but it tends to move the precipitator laterally to In the present construction this is avoided by dividing the plates into two'approximately equal groups and jarring the groups separately. This is shown in Fig. 3 where one member 44 is jarring half the plates from one side, while another member 44 is jarring the other half of plates from the opposite side. This tends to neutralize the side motion of the plates with the result that the precipitator as a whole receives no lateral motion.

Switch 5 in" Fig. 1' can be adjusted angularly on shaft 3 which makes it possible to discharge condenser 28 at the-desired instant in the energization cycle, and the shapeand spacing of tips '7 can be altered thereby changing the characteristics of the spark gaps between tips '7v and the stationary shoes 20', 21' and 22' of the switch.

When jumper 23 is removed the switch can be" made to, distribute the energy so that two units will receive energy separately, which is an especially useful condition when the units have different electrical characteristics. In many mstallations there is no particular advantage gained through the use of such a distributing switch and an ordinary spark gap can be substituted for it as shown in Fig. 4. In this arrangement of the circuit the members and connections are quite similar to those shown in Fig. 1, except that spark gap 52 replaces rotating switch 5 and conductors 53 and 54 replace conductors 21 and 22, but the characteristics of the circuit are not now so fully under control because the only possibilities in spark control are to change the size and spacing of the terminals of spark gap 52. Choke coils 55 prevent the impulses from rushing undamped down one particular conductor and not supplying energy to the other conductor, a condition which has been found to exist in varying degrees when steep wave front impulses are utilized in circuits of the nature described. The discharge electrodes are indicated as wires in cross-section at 56, and the collecting electrodes 57 are common to. all the units. The numeral 58 identifies insulated non-discharging electrodes which are a part of the condenser unit. They are shown in this figure as plate-like members.

The parts of condenser 28 are spaced and supported in much the same way as those in units 33a and 33b, but, whereas separate electrical connections are made to the high voltage-electrodes in the latter units, as indicated by conductors 24 passing through insulating bushings 59 and insulating plates 60, connection 20 is connected to the mechanical support provided for the insulated members of unit 28. It will also be noted that only one rapping member 44 is shown. When the plates of this unit are small and not many in number, a unidirectional rapping is satisfactory,

but in large units the two-way rapping indicated tric, require a great deal of space, and because of the necessity of placing a safeguarding structure around suchcondensers the space required is often more than can be provided adjacent an electrical treater. An advantage of the gaseous type condenser is that it is simpler than the condenser with oil or wax as a dielectric and if kept clean is not likely to puncture. However, should it puncture no damage is done as the dielectric is selfhealing. Another advantage of this type of condenser is the rapidity with which it takes a charge and discharges the same. As illustrated, the condenser functions as part of the precipitating apparatus and has a definite part in the removal of suspended particles from the gases. If in a particular problem there is no great advantage in having it function in this way, it can be placed in any position in the gas stream. In the use of a revolving switch to furnish spark gaps and to distribute the energy impulses great flexibility is afforded. Not only can the'gaps be changed in length and the time when breakdown is effected be controlled, but its use makes easy the energizetion of precipltator units every other half cycle, which tends to decrease the amount of energy required for the operation of a precipitator with a plurality of units. Also, when more than one liu iza

unit is energized, switch 5 in Fig. 1 can be seconstructed that the characteristics of the energy impulse going to one unit of the precipitator will be different than those going to another. I

It has been found that the capacitance of a condenser used in the manner described should preferably be at least as great as the capacitance of all the precipitating units to which it is cannected. For example, if the rods in unit 28 in Fig. 1 are in outside diameter and spaced 2" apart along the flue, the discharge electrodes can be .05 in diameter and positioned 6" apart along the flue. The collecting plates 34 can be 8" apart in all units, but this is not necessary if there is any reason for changing the spacing in the condemer unit. It is preferable-that with the dimensions above given there should be one nonionizing rod in the condenser for every discharge electrode in the ionizing units. In Fig. 1 only one rod is shown for every two discharge wires, but that is because only one set of discharge wires is being energized at a given time. If both units were energized at the same time, which would be true if jumper 23 was in place then the capacity of the condenser should be doubled over that shown.

It is, of course, not necessary that the apparatus be constructed exactly as shown in the drawings or described in the above specifications. Many changes in size, shape, and arrangement of parts may be possible or desirable. For instance, while it is pointed out that satisfactory results are obtained when the capacitance of the condenser is equal to the capacitance of the ionizing units to which it is at any one time connected, it is advisable at times to increase the capacitance of the condenser to at least twice that of the ionizing units.

The energy directing means may be a thermionic valve or several such valves connected to permit only unidirectional flow of electric current. A

spark gap of great flexibility is made possible by a synchronously rotated mechanical switch with so-called stationary shoes on adjustable supports which permit the shoes to be individually moved radially and'angularlywith respect to the axis of rotation; and the shoes may be of diflerent lengths. Other changes will be obvious to those skilled in the art which can be made without departing from the scope of the invention, which broadly comprises means for impressing-high tension electrical impulses of steep wave front and short duration across the complementary electrodes of a device for subjecting fluids to electrical treatment, said means essentially comprising an energy directing device adapted to connect the electrodes with a source of high tension altemating current at determinable intervals, a spark gap and a condenser in which the dielectric is the.

fluid being treated.

I claim:

1. An electrical circuit for impressing high tension' electrical impulses of steep wave front and short duration across the complementary electrodes of a device for subjecting fluids to electrical treatment, comprising in combination, means providing high tension alternating current, an

energy directing device adapted to connect said electrodes with said current providing means at determinable intervals, a spark gap and a condenser comprising condenser elements positioned to include a stream of the fluid being treated as the dielectric. i

2. An electrical circuit for impressing high tension electrical impulses of steep wave front and short duration across the complementary electrodes of a device for subjecting fluids to electrical treatment, comprising in combination, means providing high tension alternating current,

an energy directing device adapted to convert said alternating current into unidirectional pulsating current, a spark gap and a condenser comprising condenser elements positioned to include a stream of the fluid being treated as the dielectric.

3. An electrical circuit for impressing high tension electrical impulses of steep wave front and short duration across the complementary electrodes of a device for subjecting fluids to electrical treatment, comprising in combination, means providing high tension alternating current, a mechanical switch adapted to connect said electrodes with said current providing means at determinable intervals, a spark gap and a condenser comprising condenser elements positioned to include a stream of the fluid being treated as the dielectric.

4. An electrical circuit for impressing high tension electrical impulses of steep wave front and short duration across the complementary electrodes of a device for subjecting fluids to electrical I treatment, comprising in combination, means providing high tension alternating current, a mechanical switch adapted to convert said alternating current into unidirectional pulsating current, a spark gap and a condenser comprising condenser elements positioned tic/include a stream of the fluid being treated as the dielectric.

5. An electrical circuit for impressing high tension electrical impulses of steep wave front and short duration across the complementary electrodes of a device for subjecting fluids to electrical treatment, comprising in combination, means providing high tension alternating curent, a mechanical switch adapte to convert said alternating current into uni tional pulsating current, a rotary spark gap and a condenser comprising condenser elements positioned to include a stream of the fluid being treated as the dielectric.

6. An electrical circuit for impressing high tension electrical impulses of steep wave front and short duration across the complementary electrodes of a device for subjecting fluids to electrical treatment, comprising in combination, means providing high tension alternating current, a mechanical switch adapted to convert said alternating current into unidirectional pulsating cur- 125.

rent, a rotary spark gap rotatable synchronously with said mechanical switch and a'condenser in which the dielectric is the fluid being treated.

I. An electrical circuit for impressing high ten- I sion electrical impulses of steep wave front and short duration across the complementary electrodes or a device for subjecting fluids to electrical treatment, comprising in combination, means providing high tension alternating current, a mechanical switchadapted to convert said alternating current into unidirectional pulsating current, a rotary spark gap rotatable synchronously with said mechanical switch and adapted to direct high tension impulses in alternation to separate sections of said fluid treating'device and a condenser in which the dielectric-is the fluid being treated. r I

8. Apparatus for subjecting fluids to electrical treatment comprising a set of complementary discharge and collecting electrodes, means providing -high tension alternating-current, and connecting means for impressing said high tension current across said electrodes, said connecting means including an energy directing device adapted to connect said .electrodeswith said current provid 150 ing means at determinable intervals, a'spark gap and a condenser comprising condenser elements positioned to include a stream of fluid being treated as the dielectric. V

9. Apparatus for subjecting fluids to electrical treatment comprising a set of complementary discharge and collecting electrodes, means providing high tension alternating current and connecting means for impressing said high tension current across said electrodes, said connecting means including a mechanical switch adapted to convert said alternating current into unidirectional pulsating current, a rotary spark gap rotatable synchronously with said mechanical switch and a condenser in which the dielectric is the fluid being treated;

10. Apparatus for subjecting fluids to electrical treatment comprising a plurality of sets of complementary discharge and collecting electrodes,

means providing high tension alternating current and connecting means for impressing said high tension current across said electrodes, said connecting means including a mechanical switch adapted to convert said alternating current into unidirectional pulsating current, a rotary spark gap rotatable synchronously with said mechanical switch and adapted to direct high tension impulses in alternation to separate sets of electrodes, and a condenser in which the dielectric is the fluid being treated.

11. Apparatus for subjecting fluids to electrical treatment comprising a set of complementary discharge and collecting electrodes, a set of condenser elements, means for passing fluid to be treated between said discharge and collecting electrodes and said condenser elements in succession, means providing high tension alternating current and connecting means for impressing said high tension current across said electrodes, said connecting means including anenergy directing device adapted to connect said electrodes with said current providing means at determinable in tervals, a spark gap, and said condenser elements.

12. Apparatus for subjecting fluids to electrical treatment comprising-a set of complementary discharge and collecting electrodes, a set of condenser elements, means for passing fluid to he treated between said discharge and collecting electrodes and said condenser elements in suesession, means providing high tension alternating current and connecting means for impressing said-high tension current across said electrodes, said connecting means including a mechanical switch adapted to convert said alternating cur rent into unidirectional pulsating current, s rotary spark gap rotatable synchronously with said mechanical switch, and said condenser elements.

13. Apparatus for subjecting fluids to electrical treatment comprising a set of 'complementary discharge and collecting electrodes, a set of condenser elements, means for passing fluid to be treated between said discharge and collecting electrodes and said condenser elements in succession, means for subjecting said electrodes and condenser elements to periodic jarring,

means providing high tension alternating cur-=- rent and connecting means for impressing said high tension current across said electrodes, said connecting means including an energy directing device adapted to connect said electrodes with said current providing means at determinable in--v tervals, a spark gap, and said condenser elements. 7 14. In apparatus for precipitating suspended solids from gases, complementary discharge and plate electrodes adapted to ionize gases passed therebetween, condenser elements adapted to'subject gases passed therebetween to the action of an electric field, means for passing gases to be treated serially between said electrodes and said condenser elements, means for periodically impressing across said electrodes electrical impulses of steep wave front and high potential, said means including a source of high potential alternating current, an energy directing device adapted to connect said electrodes with said source of current at determinable intervals, and a spark gap connected in parallel with said condenser elements,

'15. In apparatus for precipitating suspended solids from gases, complementary discharge and plate electrodes adapted to ionize gases passed therebetween, condenser elements adapted to subject gases passed therebetween to the action of an electric field, means for passing gases to be treated serially between said electrodes and said condenser elements, means for periodically impressing across said electrodes electrical impulses of steep wave front and high potential, said means including a source of high potential alternating current, a mechanical switch adapted Mill to convert said alternating current into unidical switch and connected in parallel with said condenser elements.

16. An electrical circuit for impressing high tension electrical impulses of steep wave front and short duration across the complementary electrodes oi a device for subjecting fluids to electrical treatment, comprising in combination, means providing high tension alternating current, an energy directing device adapted to connect said electrodes with said current providing means at determinable intervals, a spark gap, a condenser comprising condenser elements positioned to include a stream of the fluid being treated asthe dielectric, and means for maintaining said condenser elements substantially free of deposited material.

it. An electrical circuit for impressing high tension electricalimpulses of steep wave front and short duration across the complementary electrodes of a device for subjecting iluidsto electrical treatment, comprising in combination, means providing high tension alternating current, an. energy directing device adapted to connect said electrodes with said current providing means at deteahle intervals, a spark gap, a condenser comprising condenser elements positioned to include a stream or the fluid being treated as the dielectric, and means for subjecting said condenser elements to periodic jarring.

18. Apparatus for subjecting fluids to electrical treatment comprising a set of complementary discharge andcollecting electrodes, means providing high tension alternating current, and connecting means for impressing said high tension current across said electrodes, said connecting means including an energy directing device adapted to connect said electrodes with said current providing means at determinable intervals, a spark gap and a condenser comprising condenser elements positioned to include a stream 01' the fluid being treated as the dielectric, and surge resisting inn pedances in the connections tosaid discharge electrodes.

its

Images