US1889360A - Liquid seal - Google Patents

Description

NOV. 29, P HERBER 1,889,360

LIQUID SEAL Filed May 26, 1931 Patented Nov. 29 1932 PIERRE fifEItBER, or MIDDLESEX, New

JERSEY, ASSIGNOB TO enemas conromrron,

OF NEW YORK, N. Y, A CORPORATION OF NEW YORK LIQUID SEAL Application filed Key '26,

This invention relates to liquid seals and particularly to seals for preventing the passage of gas through the opening in a wall of conducting material through which extends a conductor which is normally at an electrical potential substantially different from that of the wall. The invention is particularly useful in the art of electrical precipitation for sealing the opening in the gas chamber at the n point at which the high tension conductor is led into the chamber.

In apparatus for the electrical precipitation of suspended solids and liquids {from gases according to the Cottrell process, the

high tension conductor to which the discharge electrodes are connected must be insulated from the chamber walls, which are generally at ground potential. The conductor is led into the chamber through an insulating 2o bushing disposed in achamber adjacent the main chamber. To prevent the deposition on the insulating bushing of: a coating of conducting materials, it has been found desirable to provide a gas tight seal between the main chamber and the insulator chamber.

One form of oil seal which has been proposed comprises an annular trough filled with insulating oil, and an inverted cup-shaped hood, the edge of which extends below the surface of the oil; the conductor extends through an opening in the top wall of the hood which member fits tightly around the conductor. So long as the (inference between the pressure of the gasinside the main chamher and the pressure of the atmosphere in the insulator chamber surrounding the insulata ing bushing remains constant, this type 0 seal is satisfactory in operation. However,

it was found that when the difference in pres- 4 sures changes suddenly, such as when a damper in the precipitator flue is closed, the

4 levels of the oil at the two sides of the hood change so rapidly that oil is often ejected from the trough.

An object of the present invention is to taken through an insulator f. cent the main cham and communicating 1981. Serial No. 540,129.

provide an improved form of seal for closin' the opening in the wall of a gaschamber an obtaining suitable electrical insulation between the chamber wall and an electrical conductor passing through the opening: other object is to provide a seal of t e type stated in which a liquid insulating med um is employed to close the opening against the passage of gas. A further object is to provide a liquid seal in which the surfaces which confine the liquid and define the terminals of the electrical field are so shaped and related that theliquid can assume difierent levels in the seal, with changes in gas pressure, with out appreciably altering 'hei desired properties of the seal. A further object is to provide a liquid seal for closing the opening in a gas chamber that is subject to in gas pressure, and which will retain the hquid within the seal in spite of sudden changes in the relative pressures at opposite sides of the seal.

These and other objects of the invention will be apparent from the following specification when takenwith the accompanying drawing, in which Fig. 1 is a view showing a vertical section chamber of an electrical precipitator provided with a seal constructed according to the invention,

Fig. 2 is a fragmentary view showing a verticall section taken through another form of sea An electrical precipitator e nipped with a seal constructed according to t e invention is shown in part, in Fig. 1. Disposed adjaber 1 of the precipitator therewith by a short flue 2 is an insulator chamber 3 which is divided into two portions by a horizontal partition 4 having a central opening 5, and a vertical partition 6 surrounding the opening 5 and forming, with the side wall 7 of the chamber 3, an annular trough 8. The upper portion of the vertical partition 6 is of less diameter than 90' sudden changes I in its lower portion. The upper ed e of the .sure fluctuation.

vertical partition 6 is flared outwar ly for a purpose to be hereinafter disclosed.

hollow insulator 9 secured to the bottom wall 10 of the chamber 3 carries a metal column 11 which supports one end of a high voltage member 12 which extends through the flue 2 and into the main chamber 1, which member 12 serves to support and to supply current to discharge electrodes 13, one of which is shown. A high voltage conductor 14 extends, in the usual manner, through the insulator 9 and into contact with the metal column 11 to supply current to the high voltage member 12.

Secured on the top end of the column 11 is a hood 15 having the form of an inverted cup which is disposed concentrically with re spect to the wall 7 of the chamber 3 and the of the trough 8. A su cient quantity of insulating oil 16 is introduced into the trough .8 to fill the same to a level A substantiall midway from the top to bottom of the trough 8 whereby the lower end of the hood 15 is completely immersed in the oil 16. In designing oil seals primary consideration has been given to electrical insulation and it has been customary to arrange the hood midway between the annular walls which define the trough. The hood thus divided the trou h into two annular sections having substantially difi'erent'horizontal cross-secb tions. In someinstances, the difference in area amounted to 50%,, consequently a change of oil level of two inches in the outer section was accompanied by a three inch vari-' ation in level at the inner section. This made for unstable operation under the fluctuating pressure conditions encountered in systems for treating and handling moving gases. Sudden changes in gas pressure, such as obtain when dampers are quickly which cause the difference in posite sides of the seal to rise higher than normal, with the was forced out of the seal.

According to the present invention,

pressure at opto values much result that oil to provide effective insulation is provided but the relative proportionin of the parts of the seal is such that stabi operation of the seal is maintained under adverse conditions of gas pres- The spacing c is determined by the requirement for effective gaseous insulation between the high voltage column 11 and the wall 6, and the spacing at is determined by the requirements for ample liquid insulation between the bottom of hood 15 and the adjacent surfaces of the trough 8 The-distances b, 6' between the hood and I than in the the inner wall 6 of the trough are not, however, determined solely, based upon electrical insulation. en the wall 6 1s a sim le cylindrical member, as will be discussed hereinafter in connection with the embodiment shown in Fi 2, the distance between the hood 15 and t e inner wall is so chosen that the cross-sectional area of the inner annular liquid surface is substantial? equal to the area of the annular liqui surface at the exterior of the hood 15.

When the inner wall 6 is formed of sections of different diameter, the lower section is of larger diameter to provide adequate elec-' trical clearance 0 between the top of the insulator and the wall 6, and the spacing b of this enlarged section of wall 6 from the hood15 may be approximately equal to the distance a. At the top portion of the wall 6, however, the spacing b is made substantially greater than that required for electrical insulation from the hood 15, to provide an annular space having an area approximately equal to the area of the outer annular section of the oil seal; this decrease in the diameter being possible ,due to the fact that the insulator column 11' is of less diameter than its base and therefore the necessary electrical tween column 11 and wall 6.

Further reduction of the likelihood of oil bein forced over the top of wall 6 is provided by the outward flaring of the top of wall 6, the flared ed e being preferably eaded, as indicated at 1 to reduce the concentration of the electric field at its edge.

With e ual pressures at the seal, the oil level will be approximately as indicated by line A. Under normal operation, the reduced pressure in the precipitator may raise the oil level in the outer section to the level B and cause the level in the inner section to drop to the level G. Upon a sudden rise of the pressure within the precipitator, the oil level in the outer section of the seal falls and that of the inner section rises. Since the area of the upper part of the inner section of the seal is equal to that of the outer section, the change in level in the inner section takes place at a lower rate though the oil wall 6, the outwardly flaring of this wall prevents the oil from surging over the wall.

- As sludge, properties of the oil, will collect in a valved drain pipe 18' is provided ing the sludge ofi" to a waste pipe 19. The supply of oil may be replenished through the sight gauge 20 upon removal of the stopper 21.

In the modified form of seal which is illustrated in Fig. 2, the'member 29 forms part of the wall of trough 8 for draw clearance c is provided beopposite sides of which impairs the insulating a chamber in which the gas re uirements known construction and, even level approaches the top of v i and the flaring top of pressure above the wall is normally substantially less than the pressure below the wall. A cupped member 30 is suspended from the wall member 29 and has a central opening 31 which is defined by the inner cylindrical wall 32 which cooperates with the outer wall 33 to define an annular cup or trough 34 for the reception of transformer oil or insulating fluid which is filled into the trough to approximately the level D. An electrical conductor 35 extends through opening 31- and carries a hood 36 whose lower edge depends into the trough. The inner wall of the hood 36 is provided with a downwardly flaring bafile 38. To avoid concentration of the electric fields, the outer flared edge of wall 32 is provided with a head 39, and similar beads 40, 41 are formed at the lower edges of the hood 36 and the baffle 38, respectively.

As is apparent from the drawing, the distance between the inner wall 32 and the hood 36 is materially in excess of that required for electrical insulation, the spacing being determined by the the oil seal be approximately equal. This makes it possible to employ bafiles for damping rapid fluctuations of the level liquid. 'While one baffle 38 is usually sufiicientto damp movements of the oil,add1tional baflles may be provided if desired, the only limitation being that the beaded edge 41 of the bathe must be spaced from wall 32 by a distance which afiords adequate electrical insulation.

Assuming a reduced pressure at the upper face of wall member 29 which brings the oil levels in the sections of the seal to the levels E, F, respectively, a rapid rise in pressure above the wall or a sudden decrease in pressure below the wall will tend to force the oil into the inner section of the seal. The rates of change in level at opposite sides of the hood 36 are substantially equal, and sur ing of the oil is further prevented by the baflIe .38

the wall 32.

It will be apparent that embodiments of the invention may take other forms than those herein illustrated and described.

I claim: I a

1. In an electrical apparatus, the combination with a chamber having an opening in one wall thereof, and supporting means in said chamber and extending through said opening, of a liquid insulating seal forclos- 1ng said opening, said seal comprising coaxial walls spaced from said supporting means and providing a trough for the reception of a liquid insulating medium,'a hood carried v by said supporting means and depending into said trough to divide the same into two annular interconnected sections of substantially equal horizontal cross-section.

2. The invention as set forth in claim 1, wherein one of the members defining the inner annular section of said trough is prorequirement that the cross-sectional areas oi the two annularsections of vided with baflle means for damping the movement of the liquid in said trough.

3. The invention as set forth in claim 1, wherein one of the members defining the inner annular section of said trough is provided with bafile means for damping the movement of the liquid in said trough, the

radial distance between the said baflle means and the opposed wall defining said inner annular section being substantially equal to the radial distance between said hood and the opposed wall which cooperates therewith to define the outer annular section'of said seal.

4. In a seal for insulating a member from the structure through which the member passes, the combination of inner and outer walls defining an annular trough for the reception of an insulating liquid and a central opening, a member extending through said opening, and a hood carried by said member and having the lower edge thereof extending into said annular trough to divide said trough into two annular sections of substantially equal horizontal cross-section.

5. An insulating liquid seal of the type comprising coaxial walls defining a trough for the reception of a liquid insulating medium, an electrical conductor extending through the opening defined by the inner wall, and a hood carried by said conductor and depending into said trough, characterized by the fact that said hood divides said trough into two annular sections of substantially equal horizontal cross-section.

6. The invention as set forth in claim 5, wherein the upper edge of one of the said walls is flared towards said hood, thereby to prevent sudden changes in pressure from forcing the liquid out of said trough.

7. In an oil seal, a cup shaped member having coaxial inner and outer walls defining a trough forthe reception of a liquid insulating medium, an electrical conductor extending through the opening defined by the inner wall and subjecteto an electrical potential substantially difierent from that of said cup shaped member, said conductor and depending into said trough, the lower portion of the inner wall being spaced from 'sad hood by a distance substantially equal to that between said outer wall and said hood, and the upper portion of said inner hood being of reduced diameter to provide an annular space within said hood of approximately the same horizontal crosssection as that of the annular space between said hood and said outer wall member.

8. An insulating seal for an opening in a gas chamber, said seal comprising walls of said chamber defining a trough for the reception of a liquid insulating medium, an electrical conductor extending through the opening defined by the inner wall, a hood carried by said conductor and dividing said trough into two annular sections, the diameter a hood carried by of said llood bein eter of said trough, and a bame g in excess of the mean diamcarried by one of the opposed members defining the inner annularsection of said trou 9. The inventionas set forth ineclaim 8,

wherein said ner wall and 1s spaced YPI ried by the-said infrom said hood by a distance approximately equal to the distance between said hood and the outer wall.

In testimony whereofbl affix my si ature.

RRE HER ER. 1

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