US2329961A - Apparatus for electrolytic protection of vessels from corrosion - Google Patents

Description

p w. L. WALKER 2,329,961

APPARATUS FOR ELECTRQLYTIC PROTECTION OF VESSELS FROM CORROSION Filed Aug. 12, 1940 mum ATTORNEY.

Patented Sept. 21, 1943 APPARATUS 'Fon. ELECTROLYTIC rno'rEc- TION or VESSELS mom coanosroN an... Louis Walker, San Francisco, Calif.

Application August 12, 1940, Serial No. 352,25;

2 Claims.

This invention relates to a method and apparatus for electrolytic protection of vessels from corrosion.

It is well known that corrosion, commonly known as rust, is caused by the existence of two, or more, dissimilar elements in the presence of moisture, which setsup an electro-chemical action known as electrolysis. During this process water is broken down by an electric current and the hydrogen ions travel to the negative electrode, the cathode, and the oxygen ions travel to the positive electrode, the anode. Oxygen ions on reaching suitable metal surface react chemically thereupon and form various oxides thus destroying said surface. Hence, in order to pre- V vent corrosion of submerged metallic surfaces, it

is necessary to make the same cathodes. This is done by immersing an anode into the electrolyte and applying a direct current of slightly greater force than that generated by the electrolytic process, and by making the surface to be protected the cathode.

In order to protect a. large area from corrosion, a voltage in excess of 1.6 v. must be necessarily applied. -In the latter case, water decomposes readily into hydrogen and oxygen. The free oxygen will rapidly destroy all metal surfaces unless it is eliminated from the electrolyte and thus prevented from contacting said surfaces.

It is the object of this invention to provide a new method of electrolytic prevention of corrosion of the submerged surfaces in which a current of any desirable voltage and amperage may be used.

Another object of my invention is to provide a method of the type described which includes "the elimination of oxygen from the electrolyte.

Another object of my invention is to provide an apparatus for preventing corrosion as aforesaid which is operated on a current of substantially higher voltage than that which ;decomposes water and in which means is provided for collecting free oxygen and other anodic elements and for venting the some out of the vessel.

Another object of this invention is to provide a device of the type described which is simple in construction, cheap to manufacture, durable, and eflicient for the'purpose intended.

Other objects and advantages will appear as the specification proceeds and the particular features of the device will be specifically pointed out in the appended claims. I g

In this specification and the annexed drawing, the invention is illustrated in the form considered to be the best, but it is to be understood, that the invention is not limited to such form; and it is also to be understood that in and by the claims following the description, it is desired to form of my invention.

My method for preventing corrosion of submerged surfaces and for restoring the corroded surfaces consists of inserting of an anode, preferably made of non-corrosive metal, into the electrolyte, contained in a vessel, such as a boiler, tank, condenser, pipe. The electrolyte in most cases is an ordinary water, and the corroded surfaces are the walls of a vessel containing said electrolyte. Positive current is applied to said anode, the voltage and amperage of which depends upon the size of said vessel. Generally this current is of about 24 v., which, as I have found, is most practical in average installations. Negative current is applied to the vessel thus making the same the cathode.

The current, set up in the vessel, decomposes the water into hydrogen and oxygen. Hydrogen travels in form of ions to the inner surface of the vessel and upon contacting the same becomes hydrogen gas. The latter may combine again with the oxygen contained in the water and produce water, or with oxygen in the iron oxide. The latter process transforms iron oxide into almost pure iron, thus reducing the obstructions in pipes.

The other component part of decomposed water, oxygen, cannot be left free in the electrolyte, as it will cause more harm to the surfaces of the vessel than the ordinary corrosive process. Therefore, the next step in my method is the elimination of free oxygen from the vessel. When the current is set up in the vessel, the oxygen ions will travel to the anode and upon contacting the same they become oxygen gas, which will rise upward in the surrounding water. The liberated oxygen gas is trapped and is not permitted to travel with the water in the vessel thus eliminating the danger of oxygen contacting the vessels surfaces. Various devices may be used for trapping oxygen. They must be made of noncorrosive nonconductive substance, such as ceramic, plastic or hard rubber in order to prevent their oxidation. The oxygen gas is collected therein and released into the atmosphere, thus leaving hydrogen in the water which constantly forms a protecting invisible film on the inner surfaces of the vessel.

The apparatus which I employ in connection with my method, as shown in Figs. 1 and 2, consists of an anode in the form of abar 2, preferably made out of noble-noncorrosive-metal, confined within a chamber 3. The latter is formed by a cylinder 4 the inner wall'of which is covered by an insulating material 5 such as rubber or the like. 1

The cylinder 4 is secured, preferably by welding, to a vessel I, such as a boiler, tank, condenser, etc. which it is desirable to protect from the corrosion.

The top of the cylinder 4 carries a disk 9 removably secured thereto. n the top of the disk 3 there is placed a gasket l0 upon which rests hard rubber washer l2. The latter carries thereon a soft rubber-plug |4 having a metal flange IS. The flange l5 and the disk 9 are connected by bolts l6 passing through the gasket I0 and washer l2.

The upper portion I! of the anode I is reduced in diameter and has a central longitudinal bore, or vent, IS the lower end oi? which communicates with a transverse bore I9 formed in the upper portion of the bar 2. The portion I! is outwardly threaded and carries a washer 2|, and nuts 22 and 23 betweenwhich a terminal 25 of the electric wire 26 is securely locked. The wire 26 carries positive current and the wire 21 connected at the far end of the vessel 1 carriesnegative current.

In case the vessel 1 contains fluid therein under pressure,'such as in case of a boiler, water pressure tank, etc., I provide a gas release valve 3|! on the upper end of the-portion I1. This valve may be of any suitable construction and is shown in the drawing ascomprising a chamber 3| in which a float 32 having a valve 33 on the top thereof floats in fluid 34. Whenever the gas in the chamber accumulates sufflciently to force the liquid down, the float 32. drops down and opens a passage 35 in the top of the chamber 3| thus releasing the gas in said chamber.

In case there is no pressure inside of the vessel, the vent l8 empties into the air.

The operation of the apparatus is as follows;

A suitable positive current is applied to the anode I, and a negative current to the vessel I. A flow of direct current is established'between the anode and the cathode, the vessel, through the electrolyte. The hydrogen ions start to move to the cathode, the walls of the vessel, and the anodic ions to the anode, and upon contacting the cathode and anode respectively they become the products above mentioned or gases. oxygen and other anodic gases being liberated from the electrolyte rise upwardly and being confined within the chamber 2 collect in theupper portion of said chamber, wherefrom they escape The.

through the transverse bore l9 and the central bore I 8. The hydrogen forms on the walls of the vessel a protective film which prevents corrosion and destroys the existing I corrosion by uniting with the oxygen of the oxides and with the various elements deposited on the walls'of the vessel.

My apparatus may be successfully used inconnection with the water systems, and the Fig. 2 shows one method of attaching of my apparatus to such system. -A water pipe 40 is provided with a short branch pipe 4| having a flange 42 on the upper free end thereof. The apparatus is in-- serted into said branch pipe and is secured to said flange 42 by bolts 44. It is noted that in order to prevent the possible escape of oxygen, the anode is made considerably shorter so that the whole of it is conflnedwithin the protecting sleeve, 7.

Fig. 3 shows a modified form of my device comprising a ceramic bell 5|) instead of the sleeve I. Instead of a single bar anode i, as shown in Fig. 1, the anode 52 of this modified form is constructed of a plurality of bars 53 secured into a plate 54, which in turnis secured to a central bar 55. The latter is insulated from the vessel wall 56 by insulations 57 and 58, and has a centrally located vent 6B connecting the chamber within the bell 50 with the pressure release valve 30. The operation of this device is exactly the same of the device shown in Fig. 1.

Having thus described my invention, I claim:

1. An apparatus for preventing corrosion of submerged metallic surfaces and for restoring the corroded metallic surfaces of a vessel containing an electrolyte, comprising an anode suspended inside of said vessel; said anode and vessel being electrically connected to positive and negative terminals respectively, of a source of direct current; a chamber around said anode, the

inner surface of the wall and of the top 01 which is covered with insulating material; said wall being insulated from the anode; said chamber being opened at the bottom and closed at the top and adapted to collect gas generated in the electrolyte by the current passing between said vessel and anode; a vent leading from the top of said chamber to the atmosphere; and means for release of said gas out of said chamber Without said gas contacting said submerged metallic surfaces.

2. In combination with a closed vessel containing an electrolyte under pressure therein, of an apparatus for preventing corrosion of submerged metallic surfaces comprising an anode suspended inside of said vessel; said anode and vessel being electrically connected to positive and negative terminals respectively of-a source of direct current; means for collecting the gas generated in the electrolyte and formed around the anode by the current passing between said vessel and

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