US2023496A - Method for cleaning oil-covered surfaces - Google Patents

Description

Dec. 10, 1935. v J. TODD 2,023,496

METHOD FOR CLEANING OIL COVERED SURFACES Filed March 12, 1928 ll/(I114 ?//IIIIIIII/ nuunlav m' V 11v VENTOR Vern e TSaa/ TTOR 5 y Patented Dec. 10, 1935 mz'rnon non CLEANING om-oovnmin SURFACES Verne J. Todd, Seattle, Wash. Application Mar -ch 12, 1928, Serial No. 261,092

3Claims.

This application is intended as continuation in part of the subject matter embodied in two previous applications, one being Serial No. 148,102, filed November 12, 1926, and entitled Process for j cleaning oil or grease-covered surfaces, and the other filed April 4, 1925, Serial No. 20,761, and entitled Tank cleaning process.

This invention relates to a novel, inexpensive and speedy method of and apparatus for clean .10 ing oil or grease-covered surfaces and is especially adapted to remove solid or semi-solid deposits ofthis character, which, because of their lack of fluidity, are difficult, to break down and remove.

. The object of my invention is to pmvide ,a

15 method, and means for carrying such method into place an operator in the immediate vicinity of 15 the surface to be cleaned. v

When surfaces "are covered by oils in liquid form, such surfaces can be cleaned merely by applying hot water or steam and an emulsifying or a diluting 'agent in solution thereto. In heavy J0 deposits, it is common practice to apply an emulsifying or diluting agent-to such surface by or with an agitatingagency, such as a brush or a jet of water or steam having substantial velocity, so that such agitating agency not only tends to '85 remove such deposit bodily but also aids such emulsifying or diluting agency to work into and thru such deposit.

In cleaning tanks such as the holds of tank ship to which my invention is particularly di- 40 rected, it is common practice to remove the deposits formed upon the interior surface by filling such holds with hot'steam and maintaining such steam in the tanks until the tank walls are so hot that the deposits are, practically boiled off. 45 The application of so much heat sets up great stresses in such walls due to the difference in internal and external temperatures, which difference sets up stresses in the walls sufficient to sheer the rivets and open seams with such frequency 50 that this method is barred in many cases, for example, in the, cleaning of ships belonging to the United States Navy. when tanks of this character can be opened sufflciently so that plenty of fresh air can be ch- 66 tained therein, it is common practice to send workmen into the tanks to scrape or otherwise remove deposits from such tanks. Because of the fumes in the tank, this method is not possible where no means is present to provide such ventilation.

Another method used extensively is filling such tanks with a liquid solution of a dissolving and emulsifying agent or either of them and permitting such liquid to stand-in such holds for 12 hours to several days until the deposits have be- 19 come loosened, and then pumping such liquid from the holds. Although such liquid can be used over and over to clean tanks, a great amount of ei rpense is incurred in pumping the liquid into and out of the tanks, in storing such liquid be- 15 1 tween times, as well as in the initial cost of the liquid itself.

I have discovered that if a liquid solvent or dilutent of such deposits and an emulsifier thereof are heated and presented to such surface sigo multaneously the solvent or dilutent will liquefy the deposit so that the emulsifier can act therewith to release the bond between such covering and the surface to which it adhers. I have fur- 'ther discovered that by forming a very strong 25 concentration of such materials inintimate intermlxture such materials can be buoyantly carried to distant surfaces to be cleaned by vapors, such'as steam, and be present at such surfaces to perform their function efliciently. P I embody such discovery in my improved method by atomizing, substantially simultaneously, an emulsifier and a solvent or dilutent of such covering by a jet of steam and introduce such steam and materials thus atomized into a tank or other 86 closed chamber to be cleaned. The steam buoyantly carries such materials to all parts of the tank and when it comes into contact with the walls of such tankthe steam condenses, liquefying the water content thereof, thus supplying 40 the emulsifying agent with water wherewith to form a water-and-oil emulsion with such oil arrangement of the device for practicing such method.

In a co-pending application for United States Letters Patent, Serial No. 274,349, filed May 1, 1928, I describe a mixture and a method of compounding the same, in which such dilutent or solvent and such emulsifying agent or agents are thoroughly intermixed and arranged in convenient form for handling. In the accompanying drawing, I have illustrated devices used for handling such convenient mixture but I wish it understood that my method and means are not limited to the using of a mixture but are equally adapted to introduce the various ingredients separately into the atomizer so that they can be broken up and buoyantly carried by the steam.

In the drawing, I show diagrammatically a supply tank a having means, such as a steam coil a, for preheating such diluting and emulsirying agent so as to make it quite fluid. A supply pipe b leads into a pump 0 which discharges thru a pipe b into an atomizing nozzle (1. Such nozzle is enclosed in a steam casing e which is of substantially the same cross-sectional area as the steam supply pipe I up to a point substantially alongside the tip (1' of the nozzle. At this point e the casing flares outwardly forming a Venturi-like steam nozzle. The agent is sprayed and quite flnely divided by the nozzle 11 because of the pressure built up by the pump 0 and is further atomized and intermixed with the expanding steam in the flaring throat e. The steam breaks up such agent quite flnely and carries either chemically or mechanically such mixture in atomized form to all parts of the tank g, which is closed except perhaps for a relatively small vent g and thus such steam is prevented from escaping. The walls of such tank not previously preheated are thus colder than the point of vaporization of steam and thus when such steam comes in contact with suchwalls it condenses, depositing the diluting and emulsifying agents upon such wall with such condensation, thus supplying all of the necessary ingredients for an oil-and-water-emulsion with the oil covering.

When suihcient steam has been introduced it is cut off or diminished and when sufficient steam has condensed, depending upon the peculiarities, quantities and difficulties in emulsifying such covering, such tanks are opened permitting the gases to escape. Water directed by high pressure nozzles is then applied to the walls and the covering is easily washed and drained 01!.

Although I show apparatus specifically devised for introducing the diluting. and emulsifying agents in mixed form and by a single pump, it

is quite evident that they could be introduced separately by duplicating such pump elements, in fact it is possible to introduce each emulsifler separately in this manner. I do not wish my invention limited to the use of such agents T in mixed form but show devices for utilizing five to forty pounds of seventy-six per cent sodium or potassium hydroxide and from three to fifteen gallons of water. I have discovered although I have not been able to discover why this should be. One theory, however, is that oils which I refer to as marine-animal oils contain some organic acid or acids not present in vegetable or land-animal oils or fats.

Such soap is made in the usual manner by making a solution of the sodium or potassium hydroxide with the water and adding such solution slowly to the marine-animal oil before the mixture is brought to a boil and permitting the 1 entire mixture to boil until saponification is complete. After saponification, I add from fifty to eighty pounds of trisodium phosphate, preferably adding such trisodium phosphate slowly to the soap so that the latter is not cooled unduly 15 and so that it continues substantially at a boiling temperature. Twenty-five to fifty pounds of sodium carbonate is added similarly and then three to eight gallons of a commercial grade of water solution of sodium silicate. I add sixty to eighty gallons of hydrocarbon solvent of from to 35 Baum sold on the market as saw or furnace oil and which is the lightest grade of Diesel oil stock, to the mixture, also adding this slowly so as to maintain the mixture at or near 25 the boiling point.

The hydrocarbon solvent is stirred thoroughly into the mixture and the mixture is continued to be stirred for several minutes until an emulsion is formed, which, when sampled and chilled, assumes a jelly-like consistency. This test is preferably made by removing a small quantity from the batch and dashing it upon a cold test board.

When ready for use or when compounding, I add from two hundred to three hundred per cent more of such solvent depending upon the refractory nature of the covering to be removed. The solvent is added to the concentrated mixture by heating such mixture until it is fluid and by adding such solvent slowly to the mixture so that the whole is maintained at or near boiling. The diluted cleansing agent in this condition seemingly does not dissolve the emulsifying agents completely, probably because of the ab- 5 sence of suflicient water. Thus, when the diluted mixture is atomized by steam, it is buoyantly carried by the latter to a surface, is deposited upon such surface, condenses, and the condensation and the oil-or-grease-covering forms an emulsion.

Most of my experiments have been carried on in the cleaning of the inside walls of tanks, such as tank cars and tank ships. Such walls accumulate a heavy coating of solid and serm-solid 5 3 materials, which difier greatly, some being of paraffin base and some being of asphalt base. Some of such oils are from animal sources, some are fish oils and some are vegetable oils. Such coatings also contain many impurities, but the mixture I have described, or the ingredients in the proportions noted, provides a universal cleansing agent.

In this application the cleaning'agent is introduced into the jet of steam in atomized form and is further atomized or broken up and mixed with the steam while the latter is expanding. I wish it understood that the claims appended hereto contemplate the mixture of such agent with the steam when the former is unatomized and the latter is used as an atomizing as well as a buoyant means. Further, it is possible to mix the steam and the cleaning agent when such cleaning agent is atomized and the steam is merely mixed therewith and does not further atomize such agent. I 7

consider it preferable, however, for the agent to be atomized successively by mechanical and by steam means, as in this manner a greater percentage of the cleaning agent is taken up and thoroughly intermixed with the steam.

When the collective'term a detergent materia is used, I wish it understood that such term refers to the materials used for aiding in the removal of deposits such as I have described. As I have previously pointed out, such deposits differ in base, in consistency and impurities present and some require different treating materials than others and the treating material I have described in the specification has been successfully used to assist in the removal of all deposits. 'Some of such deposits, if their composition is definitely known, can be treated'with one or more of the materials in such mixture and some even without the. use of a penetrating agent. The mixture that.

I have described seemingly is universal in its application, but inmany cases has excess materials not needed for the removal of such deposits and thus such terms used in my claims cover only .such materials necessarily provided for the removal of the particular deposit acted upon.

I wish the term a floating fog" to be construed as that condition in which the cleaning fluid or detergent material is buoyantly carried by steam.

I claim:

1. The method of treating viscous hydrocarbon deposits to aid in their removal from the interior I surfaces of a substantially closed container, consisting in producing a body of detergent material including 'a saponified fat, 'trisodium phosphate, sodium carbonate, sodium silicate, and a hydrocarbon solvent intimately intermixed with steam and of such fineness that said material is buoyantly carried by the steam, the mixture constituting a floating fog, introducing said fog into the container, maintaining the flow of said floating fog into said container and retaining said fog in intimate contact with said surfaces until the vaporized constituents thereof collect and con- 5 dense upon said deposits and loosen the bond between the deposits and the tank walls upon which said deposits have accumulated.

2. The method of treating hydrocarbon deposits to aid in their removal from the inner sur- 1 faces of a substantially closed container, consistcumulated.

3. The method of treating hydrocarbon deposits to aidin their removal from the inner surfaces of a substantially closed container, consisting in discharging minute particles of a detergent in emulsified form comprising saponified marineanimal oil, water soluble alkaline detergents, and

a hydrocarbongrease solvent, said detergent being intimately intermixed with and buoyantly carried by steam, into the container, maintaining the flow of mixture in a buoyant form into the container, and retaining the mixture in intimate contact with said surfaces until the vaporized constituents thereof collect and condense upon said deposits and loosen them from the surfaces upon which said deposits have accumulated.

VERNE J. 'ronn.

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