US2806896A

US2806896A - Insulator compartment and control therefor

Info

Publication number: US2806896A
Application number: US283634A
Authority: US
Inventors: Rudolf G Streuber; Harry L Richardson
Original assignee: Research Corp
Current assignee: Research Corp
Priority date: 1952-04-22
Filing date: 1952-04-22
Publication date: 1957-09-17
Anticipated expiration: 1974-09-17

Description

Sept. 17, 1 957 R. G. STREUBER ETAL 2,8

INSULATOR COMPARTMENT AND CONTROL Filed April 22, 1952 THEREFOR 5 Sheets-sheet 1 INVENTORS RU DOLF G. STREUBER HARRY L. RICHARDSON ATTORNEY p 1957 R. a. STREUBER ETAL 2,806,896

I INSULNl'OR COMPARTMENT AND CONTROL THEREFOR Filed April 22, 1952 3 SheetsSheet 2 INVENTORS RUDOLF G. STREUBER & HARRY. L. RICHARDSON ATTORNEY Sept. 17, 1957 R. G. STREUBER ETAL INSULATOR COMPARTMENT AND CONTROL THEREFOR Filed April 22, 1952 3 Sheets-Sheet 3 -INVENTORS RUDOLFG; STREUBER a HARRY RICHARDSON BY MM/7M ATTORNEY United States Patent i INSULATOR COMPARTMENT AND CONTROL THEREFOR Rudolf G. Streuber, Somerville, and Harry L. Richardson, Bound Brook, N. J., assiguors to Research Corporation, New York, N. Y., a corporation of New Yorir Application April 22, 1952, Serial No. 283,634

6 Claims. (Cl. -17418) This invention relates to improvements in insulator compartments and controls therefor, associated with electrical precipitation apparatus, and is particulary directed to an improved insulator compartment that will remain operable under wide fluctuations in the precipitator gas pressure, and to means for removing foreign liquids and gases which accumulate in the compartment.

In electrical precipitators the discharge electrode system is generally at high electrical tension while the collecting electrodes and precipitator shell are generally grounded. High tension insulators are required for bringing the high tension conductors into the precipitator chamber. To prevent deposition on the insulator of a coating of conducting materials, it has been the general practice to provide a gas tight seal between the main chamber of the precipitator and the insulator chamber.

One form of gas tight seal comprises an annular trough filled with insulating oil, and an inverted cup-shaped hood, the lower edges of which extend below the surface of the oil; the conductor extends through an opening in the top of this hood. This type of gas tight seal has not proven entirely satisfactory, as an oil seal can only be set for a limited range of pressure differences between the internal precipitator pressure and the external atmospheric pressure.

When the internal pressure changes suddenly, for example, when a damper in the precipitator flue is closed, the levels of the oil at the two sides of the hood change rapidly and the oil is often ejected from the insulator compartment. Contamination of the oil seal also effects its efficient operation. Industrial gases treated by electrical precipitation are dirty and frequently saturated with water, acids or other liquids which change the specific gravity and the volume of the insulating oil. These changes in turn affect the pressure balance in the insulator compartment and prevent its proper operation.

It is therefore an object of the invention to provide an improved form of seal for closing the opening in the wall of the gas chamber while obtaining suitable electrical insulation between the chamber and the high tension electrical conductor. A further object is to provide a liquid seal which is so shaped that the liquid can assume different levels in the seal with changes in gas pressure without loss of the sealing liquid. A further object is to provide control means for an oil seal to maintain substantially constant the specific gravity of the insulating oil. A further object is to provide means for removal of contaminating liquids and gases to maintain the oil volume substantially constant and to prevent short circuits and explosions in the insulator compartment.

These and other objects and advantages of the invention are provided by the present invention which generally comprises an insulator compartment for an electrical precipitator includinga chamber having a vertical conductor member extending thereinto, means defining with the walls of the chamber an annular trough surrounding the conductor member, a hood carried by the conductor member and dipping into the annular trough, and means Patented Sept. 17, 1957 associated with the hood for preventing sudden changes in pressure from forcing insulating liquid out of the annular trough. The invention also comprises means for removing foreign matter from the insulating liquid whereby the volume and specific gravity of the liquid is maintained substantially constant.

The invention will be more fully described with reference to the illustrative embodiments of the invention shown in the accompanying drawings, in which:

Fig. l is a diagrammatic view in partial section of an electrical precipitator with insulator compartments constructed in accordance with the principles of the invention;

Fig. 2 is an enlarged sectional view of one form of the insulator compartment of the invention with control means for the insulating oil;

Fig. 3 is a section on line 33 of the device shown in Fig. 2;

Fig. 4 is an enlarged sectional view of another form of the insulator compartment;

Fig. 5 is a section on line 55 of the device shown in Fig. 4; and

Fig. 6 is an enlarged sectional view of still another form of the insulator compartment with the preferred control means for the insulating oil.

With reference to the drawings and in particular to Figs. 1, 2 and 3, 10 is the shell of an electrical precipitator and 12 and 12' are the shells of the insulator compartments.

A high tension conductor 14 is brought into the bottom of the compartment 12, through insulating bushing 16 which projects within the supporting insulator 18 and connects with bus bar 20.

The individual discharge electrodes 22 are suspended from the bus bar 20, which passes through the precipitator compartment into the insulator compartment 12' and is supported by insulator 24.

Within each insulator compartment a ring 26 is supported by a horizontal partition 28 to form an annular trough 30. The partition 28 is provided with a central opening equal in size to the internal diameter of the ring 26 through which the

insulators

18 and 24 pass. The upper portions of the ring 26 is of less diameter than the lower portion whereby the effective volume of the upper portion of annular trough 30 is greater than its lower portion.

Secured to the high tension conductor is a hood 32 in the form of an inverted cup, which is disposed concentrically with the ring 26 with the lower edge of the cup extending below the upper edge of the ring so that the lower edge of the hood is completely immersed in the insulating oil during the normal operating range of the particular precipitator installation.

A second ring 34 is secured to the high tension conductor 14 by members 36 so that its upper end is open to the precipitator pressure.

The ring 34 is disposed concentrically with the hood 32 with the lower edge of the ring extending below the lower edge of the hood and its upper edge extending above the upper end of hood 32.

Under normal operating conditions the insulating oil level will be above lower edge of hood 32 substantially as shown in Fig. 2 of the drawings. Upon a sudden rise of the pressure within the precipitator, the oil level in the outer section of the seal falls and that in the inner section rises. Since the upper end of ring 26 is reduced in diameter the change in level between ring 26 and hood 32 takes place at a substantially low rate greatly reducing the tendency for the insulating oil to surge over the top of ring 26 and out of the insulator compartment.

When the pressure in the precipitator is reduced below the normal range the oil level between ring 26 and hood -32 is lowered. When the level of the oil in this space extends below the lower extremity of the hood 32 the oil seal is broken and air is sucked into the precipitator. In the known forms of oil seal construction the air that is sucked in through the broken oil seals boils up through the oil between the hood and the insulator compartment wall often forcing the oil into the precipitator. However, in the form of the invention shown in Figs. 2 and 3, when the oil seal is broken, the air bubbles up through the space between the hood 32 and the ring 34 so that all of the bubbles are kept away from the main body of oil substantially preventing any of the oil from being drawn into the precipitator. The bubbling that does take place in the oil between the concentric walls of hood 32 and ring 34 is kept away from the opening into the precipitator by the upper extension of ring 34, which extends substantially above the top of hood 32.

To remove sludge, water and acid from the sealing oil in order to maintain a substantially constant volume of oil in the system and to prevent arc/overs and possible explosions in the insulator compartment, a settling tank 38 is provided in the lower section of the insulator compartment.

A conduit 40 connects the lower portion of trough 30 with the top of the tank 38 and sludge, water and acid having a higher specific gravity than the insulating oil collect in the bottom of the tank. An outlet conduit 42 is connected at one end into the lower portion of the settling tank and connects into a sight tube 44 at the other end.

An automatic outlet valve 46 is provided on the sight tube below the union of the sight tube with conduit 42. The outlet valve 46 may be of any well-known electrically actuated type. For example, the valve may be spring urged in the closed position with a solenoid 47 for opening the valve, as to be more fully described hereinafter. The solenoid of the valve is energized when the foreign matter in the glass portion of the sight tube reaches a predetermined level. One form of electronic circuit for actuating the outlet valve 46 is shown in Fig. 2 of the drawings, and functions by the difference in capacitance of the sealing oil and the foreign matter between two curved plates 48 and 50 on opposite sides of the glass tube.

The plates 48 and 50 are connected across the grid bias resistance of a triode 52. When the space between platesis filled with oil, an extremely low electrical capacity exists and no current flows in the switch actuating coil 54. However, when acid, for example, rises in the space between plates 48 and 5th the capacity between the plates increases permitting a flow of current through coil 54 which closes switch 56 and sends an electrical signal to the electrical actuator of valve 46. The electrical signal continues to flow to the electrical actuator until oil replaces the acid between plates 48 and 50.

A modified form of the invention is shown in Figs. 4 and 5 and corresponding parts are provided with the same numerals as used in reference to Figs. 1 through 3.

With reference to the drawings, 12 is the shell of the insulator compartment which is divided into two sections by a horizontal partition 28. The partition has a central opening, about which ring 26 is fitted, whereby the partition, ring and the sides of chamber 12 form an annular trough 30 which is filled to a predetermined level with insulating oil. As hereinbefore described with reference to Figs. 2 and 3, the upper portion of ring 26 is of less diameter than the base portion whereby the volume of the upper and lower portions of trough 30 are different.

Secured to the high tension conductor 14 is a hood 60 in the form of an inverted cup, which is disposed concentrically with the ring 26 with the lower edge of the cup extending below the upper edge of the ring so that the lower edge of the cup is completely immersed in the insulating oil during the normal operating range of the precipitator.

A plurality of tubular members 62 are secured axially to the inner side wall of the hood. Each tubular member has a closed lower end and is provided with openings 64 and 66 adjacent the top and bottom of the tube respectively. Opening 64 at the top of each tube corresponds to an opening 64' in side wall of the hood. The lower opening 66, as clearly shown in Fig. 4 of the drawings, opens into the interior of the hood.

Under normal operating conditions the insulating oil within the hood will be above the upper edge of openings 66 substantially as shown in Fig. 4 of the drawings. Upon a sudden rise of the pressure within the precipitator, the oil level in outer section of the oil seal falls and that within the hood rises. Since the upper end of ring 26 is reduced in diameter, as the oil level approaches the top of the ring 26, the rate of change in level is substantially lower than at the beginning of the rise which greatly reduces the tendency for the insulating oil to surge over the top of the annular ring 26 and out of the insulator compartment.

When the pressure in the precipitator is reduced below the normal range, the oil between ring 26 and hood 60 is lowered, and when the level of the oil is lowered below the lower edge of the hood, air is sucked from the atmosphere into the precipitator. The passage of air around the lower edge of the hood and up through the oil in trough 36 causes violent bubbling and surging of the oil in the space between the hood and the wall of the insulator compartment, often forcing the oil into the precipitator. In this form of the invention, tubular members 62 prevent this violent surging of the oil, as the air being forced from the hood enters openings 66 in the tubular members 62, passes upwardly through the tubes and out the openings 64 without coming in contact with the main body of insulating oil.

A settling tank 63 is provided in the lower section of the insulator compartment to receive sludge, water and acids having a higher specific gravity than the insulating oil. The settling tank is connected to the main supply of oil in trough 30 by conduit 70, and a sight tube 72 for visually determining the amount of foreign matter in the insulating oil system is connected into the lower portion of tank 68 and into trough 3%. At the lower end of the sight tube conduit a valve 74 is provided whereby the foreign matter may be manually drained from the settling tank.

With reference to the form of the invention shown in Fig. 6 of the drawings, 12 is the shell of the insulator compartment which is divided into two sections by a horizontal partition 23. The partition has a central opening, about which a ring 26 is fitted, whereby the partition, the ring 26 and the sides of a chamber 12 form an annular trough 30, which is filled to a predetermined level with insulating oil.

The upper portion of ring 26 is of less diameter than the base portion whereby the volume of the upper part of the inner annular section is greater than the volume of the lower section to provide damping of the flow of insulating oil into the upper section.

Secured to the high tension conductor 14 is a hood in the form of an inverted cup, which is disposed concentrically with the annular ring 26. The lower edge of the cup is adapted to extend below the upper edge of ring 26 so that the lower edge of the cup is completely immersed in the insulating oil during normal precipitator operation.

To prevent the sealing oil from being sucked through the orifice 82, through which bus bar 20 extends, when the pressure in the precipitator is reduced to the extent that the oil level between ring 26 and hood 80 is below the lower edge of the hood, the upper level of the oil seal hood 86) is spaced below the lower edge of orifice 82. The space provided between the top of the hood and the lower edge of orifice 82 is great enough to accommodate all of the sealing oil between hood 89 and annular ring 26 substantially eliminating the loss of oil during abnormal low pressure surges within the precipitator.

To remove sludge, water and acid which collect in the sealing oil, and to maintain the volume of oil in the system substantially constant, an automatic control system 84 is provided.

A settling tank 86, into which sludge, water and acid having a higher specific gravity than the insulating oil collect, is secured adjacent the lower section of the insulator compartment. The foreign matter enters tank 86 by conduit 88 which joints the tank to the bottom of trough 30.

A second conduit 90 provides sludge-free oil to the upper portion of tank 86. The settling tank has two outlet conduits designated 92 and 94. Conduit 92 is connected at one end in to the top of the tank and the other end of the conduit discharges into the upper section of the insulator compartment, or, as shown in the drawings, into orifice 82. Conduit 92 is adapted to remove gas and air bubbles from the separating tank. Outlet conduit 94 is connected into the lowermost portion of the settling tank and is provided with an automatic outlet valve 96. This valve may be normally held in the closed position by springs and have an electrically actuated solenoid 98 adapted to open the valve when the solenoid is energized. One form of electronic control for the solenoid 98 is shown in Fig. 6 of the drawings. The electric current for the solenoid is derived from the transformer 100. One of the leads 102 from the transformer is connected to one terminal of the solenoid and the other lead 104 is connected to an electrode 106 supported within the tank 86. The circuit is completed by an electrical conductor 108 which connects the conductive wall of tank 86 to the other terminal of solenoid 98.

Since oil is substantially a non-conductor of electricity, no current will flow to the valve actuating solenoid until the oil in the tank is replaced by conductive sludge, water or acid up to the lower end of electrode 106, at which time the electrical circuit is closed and the valve will be opened. The valve remains open until the conductive material within the tank falls to a level sufficient to break contact with electrode 106. The above cycle will operate as. often as required to keep the accumulated conductive material at a predetermined level within the tank 86.

From the foregoing description it will be seen that the present invention is an improved insulation compartment, and controls therefor, whereby the aims, objects and advantages of the invention are fully accomplished.

We claim:

1. An insulator compartment for an electrical precipitator including a chamber, a support including an insulator axially disposed in the chamber, means for shutting off gaseous communication between the chamber and an electrical precipitator comprising a ring through which the support passes, the walls of the chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the support concentric with the ring and having the lower edge thereof extending into the annular trough, and conduit means having an opening adjacent the lower end of said hood, said conduit means extending substantially the length of said hood and providing a passage between said ring and the walls of said chamber for conveying gases therethrough.

2. The invention defined in claim 1 including means for removing foreign matter from the insulating liquid comprises a tank positioned below the lowest extremity of the trough, conduit means connecting the bottom of the trough with the upper portion of the tank, valve means adjacent the lower portion of the tank and an actuator for said valve responsive to the volume of foreign matter in the tank.

3. An insulator compartment for an electrical precipitator including a chamber, support means including an insulator axially disposed in the chamber, means for shutting 0E gaseous communication between the chamber and .an electrical precipitator comprising a ring through which the support means passes, the walls of the chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the support means concentric with the ring and having the lower edge thereof extending into the annular trough, a spaced sleeve about said hood carried by the conductor, said sleeve having a greater axial length than the hood, with its lower edge extending below the lower edge of the hood and the upper edge of the sleeve projecting substantially above the normal level of the insulating liquid, and means for removing foreign matter from the insulating liquid whereby the volume and specific gravity of the liquid is maintained substantially constant.

4. An insulator compartment for an electrical precipitator including a chamber, support means including an insulator, axially disposed in the chamber, means for shutting off gaseous communication between the chamber and an electrical precipitator comprising a ring through which the support means passes, the walls of the chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the support means concentric with the ring and having the lower edge thereof extending into the annular trough, a plurality of tubular members axially secured to the inner wall of the hood, each of said tubular members having an opening facing radially inwardly of the hood at their lower ends, and an opening facing radially outwardly adjacent a corresponding opening in the upper edge of the hood, and means for removing foreign mat ter from the insulating liquid whereby the volume and specific gravity of the liquid is maintained substantially constant.

5. An insulator compartment for an electrical precipitator including a chamber, support means including an insulator axially disposed in the chamber, means for shutting 01f gaseous communication between the chamber and an electrical precipitator comprising a ring through which the support means passes, the walls of the chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the support means concentric with the ring and having the lower edge thereof extending into the annular trough, a spaced sleeve about said hood carried by the conductor, said sleeve having a greater axial length than the hood, with its lower edge extending below the lower edge of the hood and the upper edge of the sleeve projecting substantially above the normal level of the insulating liquid.

6. An insulator compartment for an electrical precipitator including a chamber, support means including an insulator axially disposed in the chamber, means for shutting of]? gaseous communication between the chamber and an electrical precipitator comprising a ring through which the support means passes, the walls of the chamber and the ring defining an annular trough for the reception of an insulating liquid, a hood carried by the Support means concentric with the ring and having the lower edge thereof extending into the annular trough, a plurality of tubular members axially secured to the inner wall of the hood, each of said tubular members having an opening facing radially inwardly of the hood at their lower ends, and an opening facing radially outwardly adjacent a corresponding opening in the upper edge of the hood.

References Cited in the file of this patent UNITED STATES PATENTS 1,491,274 Rathburn Apr. 22, 1924 1,604,763 Snyder et al. Oct. 26, 1926 1,889,360 Herber Nov. 29, 1932 2,216,724 Eddy Oct. 8, 1940 2,551,404 Wiggins May 1, 1951 2,573,172 Ennis et a1 Oct. 30, 1951 FOREIGN PATENTS 338,827 Great Britain NOV- 27, 1930