US 3496334 A
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" ream 1970 w WILLIAMS 3,496,33
. ELECTRODE-810R ELECTRODE BOILERS Filed Feb. 13, 1967 B'Sheets-Sheet 1 INVENTOR M Medan... BY
I a; M+ w n. ATTORNEYS F 17, 1970 A. WILLIAMS ELECTRODES FDR ELECTRODE BOILERS Filed Feb. 13, 19s? 2 Sheets-Sheet 3 a l VENTOR w al am BY wag, Cw, Mu; will.
ATTORNEYS United States Patent US. Cl. 219-288 1 Claim ABSTRACT OF THE DISCLOSURE An electrodeboiler having an electrode with a circumferential groove between the insulation bushing and the conductive tip and the conductive tip having fiow passages for the passage of water and extending from the distal end of the trip of the groove.
This invention relates to electrode boilers of the wholly immersed electrode type. Such electrode boilers have at least one electrode extending into the boiler shell from the outside and consisting of an elongated insulation bushing, usually of porcelain, having a conductive tip within the boiler extending through the bushing. Such boilers are used for the generation of steam and for the production of hot water, the present invention being particularly, although not exclusively, applicable to boilers used for the production of hot water and operating at high tension such as 6,600 or 11,000 volts. In operation a conductive path extends between the conductive tip and the neutral point which may be in the form of a sleeve known as a neutral shield and surrounding the electrode. The invention is particularly, although not exclusively, applicable to boilers in which there is an insulating control sleeve surrounding the electrode.
According to the present invention, there is a circumferential recess extending around the electrode, one side wall of the recess being formed by the insulation bushing and the other by the conductive tip. It has been found that in certain circumstances small arcs develop on the surface of the conductive tip, for example if small bubbles of steam form on this surface. With the usual construction of electrode the outer surface is continuous, the conductive tip abutting the end of the bushing and it has been found that in certain circumstances the small arcs on the conductive tip causes damage to the insulation bushing close to the joint. By means of the present invention the outer surface of the conductive tip is spaced from the outer surface of the insulation bushing by the groove so that the risk of damage to the bushing is reduced.
Means are frequently provided for producing a flow of water over the surface of the electrode. For example, flow may take place through the insulating sleeve surrounding the electrode which is referred to above. In such cases the conductive tip preferably has passages extending through it from adjacent the distal end of the tip to the groove. In this way water will be caused to flush over the end surface of the conductive tip in the groove to prevent the formation of bubbles of steam and further to reduce the risks of damage to the insulation bushing due to arcs on the conductive tip.
One possible construction of conductive tip is to make it of a generally cylindrical outer wall surrounding a generally annular passage. The conductive tip may include an inner generally cylindrical wall surrounding the conductor extending through the length of the insulation bushing, the inner and outer cylinders being connected by radial connecting members.
Preferably a recess is formed in the distal end of the insulation bushing to receive a gasket seal between the 2 conductor extending through the bushing and the bushing itself. For example, the conductor may have a flange or collar which engages the gasket seal. In this way, the seal is protected and if it extrudes in use it will not interfere with the water flow passages.
The invention may be carried into practice in various ways, but a hot water electrode boiler embodying the invention will now be described by way of example with reference to the accompanying drawing in which:
FIGURE 1 is a longitudinal section through the boiler, and
FIGURE 2 is a longitudinal section through part of one of the electrodes of the boiler.
Referring first to FIGURE 1, the boiler shown comprises a boiler shell 21 which has a vertical axis and has an outlet aperture 22 through which water heated in the boiler can pass to a point of use. Mounted in the boiler are three electrodes, only one of which is shown in FIGURE 1. This electrode is shown in greater detail in FIGURE 2.
Each electrode includes an elongated insulation bushing 1 of porcelain having a distal end 2 and an outer end 23 which lies outside the boiler shell. Extending through the insulation bushing is a conductive rod 3 having a collar 4 welded to it. The outer end 24 of the rod 3 is formed as an electrical terminal while the inner end of the rod is threaded at 7. The rod has a collar 4 welded to it and the distal end 2 of the bushing is formed with a recess 5 to accommodate the collar 4 and there is a sealing gasket 6 between the collar 4 and the bottom of the recess 5. The end of the rod 3 carries a conductive tip assembly 8 which includes an inner tube 9 which is threaded at its lower end and is screwed to the thread 7. The outer surface of the inner tube 9 is formed with three longitudinal slots 11 spaced by around the circumference into each of which a radially extending web 12 is welded. Welded to the outer edges of the webs 12 is an outer cylindrical member 13. The conductive tip assembly 8 is locked on to the rod 3 by a dome nut 14. It will be seen that the conductive tip assembly is spaced from the insulation bushing 1 by a circumferential groove 15 and that an annular passage formed between the inner cylinder 9 and the outer cylinder 13 extends from the distal end 16 of the conductive tip assembly to the groove. The radial depth of the groove to the rod 3 is greater than the width of the groove between the end of the bushing 1 and the sleeve 8 as this keeps the current passing from the cylinder 9 or flange 4 to a low value.
Sliding on vertical guides 25 within the boiler is a cylindrical pressure chamber 26 which is fed through an axial pipe 27 with water under pressure from a pump, not shown. The pipe 27 is stationary and there is a gland 28 between this pipe and the movable pressure chamber. The movable pressure chamber 26 carries three sleeve members 17 which cooperate with the three electrodes. Each sleeve member 17 is 'made of porcelain and consists of a lower cylindrical portion 29 which dips into the pressure chamber 26, a tulip shaped portion 30 which is adjacent the distal end 16 of the conductive tip assembly 8, a cylindrical portion 31 adjacent the upper part of the tip assembly and an upper tapered portion 32.
The pressure chamber 26 also carries, by means not shown, three cylindrical conductive neutral shields 33 which are positioned adjacent the upper edges of the tapering portions 32 of the sleeve base. Raising means 34 enable the pressure chamber 26 and hence the control sleeves 17 to be raised or lowered relative to the electrodes. When the boiler is in operation, the electrode is surrounded with water and a current flows from the conductive tip assembly 8 to the neutral shield 33 through the passage between the control sleeve 17 and the insulation bushing 1, the resistance of this path being varied by axial movement of the sleeve 17. Water is pumped into the pressure chamber 26 through the pipe 27 and passes up the sleeve 17 to carry away heat generated by the passage of the current. This water flows over the inside and the outside of, the outer cylinder 13 and water passing through the annular passage flows out through the groove 15 washing over the upper end of the outer cylinder 13.
Although the outer cylinder 13 is shown with truly cylindrical surfaces, either the inner or the outer or both surfaces could be tapered so that the flow of water will impinge on the tapered surface with an improved washing effect. The outer surface may be tapered as a continuation of the taper of the insulation bushing 1 and the control sleeve 17 may be correspondingly tapered in the region adjacent the conductive tip.
What I claim as my invention and desire to secure by Letters Patent is:
1. An electrode boiler having a boiler shell, and at least one electrode extending into the boiler shell from the outside, said electrode consisting of an elongated insulation bushing of generally cylindrical shape having within the boiler shell a conductive tip at the distal end of said bushing, said tip having substantially the same radius as the distal end of said bushing, said tip being connected to a terminal at the outer end of said bushing 2 by a conductor extending through said bushing, said con ,ductor having a flange received in a depression in the distal end of said bushing, a circumferential recess extending around said electrode, one side wall of the recess [being formedby said insulation bushing and the other side by said conductive tip, said tip having a cylindrical outer wall surrounding a general annular passage and means in said annular passage defining a plurality of axially directed flow passages extending through said conductivetip from adjacent the distal end of said tip to said recess, conduit means directed to produce a flow of water over the surface of said electrode and through said axially directed flow passages, and a gasket seal in said depression in said bushing, said seal being squeezed between said flange on the conductor and the bottom of said depression.
References Cited UNITED STATES PATENTS ll/l920 Sweden.
3/ 1923 Germany.
ANTHONY BARTIS, Primary Examiner U.S c1. X.R.' 219-285, 290