US2952571A - Cleaning oily hard surfaces - Google Patents

Description

United States Patent CLEANING OILY HARD SURFACES Arthur J. Freedman, Chicago Heights, 111., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Filed Feb. 18, 1957, Ser. No. 640,615 9 Claims. (11. 134-22 This invention relates to the removal of adhering hydrocarbon oils from hard surfaces by washing with an aqueous detergent solution.

Hydrocarbon oils adhere firmly to hard surfaces such as metals, glass and ceramic and can be removed only with difficulty. The problem is of particular importance in the petroleum transportation field wherein it is necessary to clean a container of the adhering oil from a previous use before the container can be used for another oil. The problem is sufficiently serious that it is common practice to designate tanks and tanker vessels for a particular type of hydrocarbon. It is common to speak of clean oil vessels which transport things such as gasoline, kerosene, diesel fuel and heater oil and other vessels as dirty vessels becaue they transport crude, industrial and bunker fuel oils, reduced crudes and asphalts. Even in the particular category of clean oils care must be taken in introducing certain oils into oily compartments. It is undesirable to introduce kerosene into a compartment containing residual gasoline because the flash point of the kerosene would be ruined.

It is standard procedure in the petroleum transportation industry to remove hydrocarbon oils from hard surfaces by directing or impinging a stream of water at elevated temperature and pressure against the oily surface. The scouring action of the stream operating for a suflicient period of time removes the adhering oil. A particular procedure involving the use of a rotating nozzle which is lowered into the tanker compartment is universal for the cleaning of adhering oil from the metal surfaces of tanker compartments. This procedure is commonly known as Butterworthing, and is described in suificient detail in US. Patent No. 2,550,997 and the particular nozzles now favored are described in US. Patent No. 2,078,566. The Butterworthing procedure has the great drawback that a considerable period of time is required for the cleaning of particular tanker compartments. Delays caused by the need of cleaning of compartments result in economic losses and the industry is searching for better ways of removing adhering oil from hard surfaces.

An object of the invention is a method of removing adhering hydrocarbon oils from hard surfaces by the use of aqueous solution. A particular object is a method of cleaning adhering oil from tanker compartments in a shorter time than by conventional Butterworthing. Other objects become apparent in the course of the detailed de scription.

Briefly, the method of the invention removes hydrocarbon oils from hard surfaces by forcibly impinging on said oily surface an aqueous liquid stream. This liquid stream contains a minor amount of a detergent which detergent may be either the condensation reaction product of an alkylphenol and ethylene oxide or the condensation product of tall oil iwth ethylene oxide. The alkylphenol contains from 6 to 12 carbon atoms in the alkyl group and the reaction product contains from 6 to 12 ethylene oxide molecules. The tall oil reaction product contains from about 12 to 18 ethylene oxide molecules. The aqueous stream is directed at the hard surface at a pres-sure of between about and 300 p.s.i.g. at a temperature of between about and 200 F. After the adhering oil has been removed the hard surface may be freed of detergent containing aqueous solution by washing with water which does not contain any detergent.

The hard surface is cleaned of adhering oil by the use of a liquid stream consisting essentially of water and a minor amount of a non-ionic detergent. In general, the amount of detergent is between about 0.05 and 0.25 weight percent based on water; in general, 0.15 percent is sufiicient for most oils. In addition to the detergent the liquid stream may contain corrosion inhibitor such as sodium nitrite, and the various impurities which are present in fresh water. Sea water may be utilized in the invention although potable fresh water is preferred.

Very large amounts of water are needed to clean tanker compartments and this water must be disposed of. De tergents not only remove oil from hard surfaces but they tend to form a more or less stable emulsion of the removed oil and the water used to remove the oil. When a tanker is present in a harbor or on an inland water way pollution laws prevent simple dumping of the water and oil overboard. Even on the open seas it is not considered good practice to simply dump oily Water overboard. It is essential that the detergents be effective enough to remove the adhering oil and simultaneously permit ready separation of removed oil from the water by simple settling. It has been found that this very desirable combination of eflicient cleaning and easy separation is attained with non-ionic detergents selected from the class consisting of (a) the condensation reaction product of an alkylphenol, having from 6 to 12 carbon atoms in the alkyl group, with from 6 to 12 moles of ethylene oxide per mole of said phenol (b) the condensation reaction product of tall oil with from 12 to 18 moles of ethylene oxide per mole of said oil.

The cleansing action is obtained by forcibly impinging the detergent-containing water stream on the oily surface at a stream temperature between about 140 F. and 200 F. It is preferred to operate at a temperature between about F. and 200 F., particularly when removing dirty oil such as crude oil, bunker fuel oil or asphalt. The liquid stream is forcibly impinged or directed on the oily surface at a discharge pressure between about 100 and 300 p.s.i. gauge. There is some relationship between the rapidity of oil removal and the combination of stream temperature and pressure. Fastest removal is obtained at the higher temperatures combined with higher pressures.

For many oils the compartment may be used even though the hard surface does contain adhering detergentcontaining solution. The adhering solution may be readily removed from the hard surface by washing with water which does not contain detergent preferably using water at about the same temperature and pressure as used in the oil removing step.

The invention is illustrated by the following working examples carried out aboard a tanker operating on the Great Lakes. This tanker is utilized in crude oil service and in clean oil service as required by sales and refinery demands. The tanker is cleaned by Butterworthing using fresh water at about F. and 190 p.s.i.g. The Butterworthing is carried out while the tanker is tied to the dock using heat exchangers aboard ship and other equipment positioned on the dock. The Butterworthing operation is carried out by lowering a set of rotating nozzles connected to the water line through the ullage hole provided in each compartment. The nozzles are operated for about 2 hours in three positions within the compartment, namely, just above the bottom, about the mid position vertically and near the top. In order to Butterworth the remainder of the line to the nozzles. testing it was found that with these particular detergents it was possible to completely remove the adhering crude oil clean the entire vessel using fresh water at these condi- In this test the vessel was cleaned with water at about 2190 F. temperature at'the nozzle and about 190 p.s.i.g.

at the nozzle. In the test 0.10 volume percent of 'various liquid non-ionic detergents was introduced into the water. In the test the fresh water was preheated to the desired temperature and the liquid detergent introduced into the hot water line by a pump just before the water stream passed into the tanker compartment and down through After some from the metal surfaces in the compartment in a total of two hours and the nozzles needed to be shifted only twice, i.e., the nozzle was positioned near the top and bottom during the cleaning period, with the mid-position omitted. The detergent solution was removed from the metal surfaces washing with fresh water only for minutes with the nozzles positioned at about the mid-vertical point .of the compartment.

The entire vessel was cleaned by the use of these detergents in a period of 24 hours as compared to the about 3 days by ordinary Butterworthing without detergent solution. In one instance the vessel was cleaned in 2 days using comparatively cool water because hot water was not available; under these conditions ordinary Butterworthing would not have been able to clean the hard surfaces at all.

The detergents used in these tests were (1) a commercial product made by condensing diisobutylphenol with between 9 and moles of ethylene oxide per mole of said phenol (2) a commercial product made by condensing p-n-nonylphenol with 10 moles of ethylene oxide per mole of phenol, (3) a commercial product made by condensing octylphenol and 7-8 moles of ethylene oxide per mole of said phenol, and (4) a commercial product made by condensing tall oil with moles of ethylene oxide per mole of said oil. (About one 50 gallon drum of detergent was required in each instance to clean the entire vessel.)

The water which had been used to remove the oil was taken from the vessel to a tank ashore where it was settled with continuous withdrawal of oil layerand aqueous layerthe averaged settling time was about 2 hours. In the case of the tests using detergents (1) and (2) described above, respectively, a moderate amount of oil was emulsified in the aqueous phase and in the case of deter- .gents (3) and (4) described above the oil content of the aqueous phase was slight.

In all cases the amount of oil was so low that the aqueous phase could be dumped into the ship channel without fear of pollution.

TEST 2 moved. This procedure was carried out three times in order to simulate the oil-ballast cycle on the vessel. The metal strips were then removed from the bottle and fastened in a rack and sprayed for 5 seconds on each side .with -a stream from a commercial spray gun. The eifective- .ness of the detergent in each case was determined from the degree of water wetting of the steel surface after cleaning.

The cleaning operation was carried out at a Water temperature of 150 F.

The emulsification power of thedetergent was determined by introducing 200 ml. of potable water and deter- 4 gent into a wide mouth pint bottle and 2 ml. of crude oil; the bottle was shaken violently for 30 seconds. The tests were carried out with water'at 180 F. The oil-to-water ratio used was comparable to the ratio found in water samples taken from the discharge line from the vessel during a normal Butterworthing cleaning operation. The degree of separation of the oil and water phases after cessation of the shaking was observed, as well as the color of the water phase, and these compared with a blank wherein the water contained no detergent. The amount of oil remaining in the water phase after 4 hours of standing is found to be a satisfactory measure of the emulsification power of the particular detergent. The degree of emulsification was noted as severe, moderate, or slight. The amount of emulsification at moderate or slight degrees is such that the water can be disposed into places where normal sewage or waste may be disposed of without pollution problems.

A blank run'was made with water containing no detergent, in both the cleaning test and the emulsification test the cleaning power was poor, however, the water phase a after settling contained no oil. In all tests commercially available detergents were used. The results of these laboratory tests are set out in Table 1 below.

Table 1 Detergent Cleaning Emulsifica- Power tion Degree Nrmp Poor- None. Diisobutylpheuol with 9-10 ethylene Exce1lent Moderate.

oxide groups. Dioctyl sodium sulfosuccinate do Severe. Nonylphenol with 12 ethylene oxide do Moderate.

groups. Polyethylene glycol ether of o'ctylphenol. do Severe. Nonyllpheuol with-10 moles of ethylene do Moderate.

0x1 e. Talloilwith 15 moles of ethylene oxide do Slight. octyllphenol with 7-8 moles of ethylene do Do.

on e.

In all the tests the detergent was present in the aqueous .solution in the amount of Olpercent.

The above results show that all detergents do not produce the needed combination of excellent cleaning power and low emulsification degree. The class of detergents used in the invention herein possess to an eminently suitable degree both these more or less contrary abilities.

Thus having described the invention, what is claimed is: l. A method of cleaning a tanker compartment to remove hydrocarbon oil adhering to the walls of said compartment, which method comprises washing the surfaces in said compartment with an aqueous solution directed against said surfaces at a discharge pressure of between about and 300 p.s.i.g. and at a discharge temperature between about F. and 200 'F., for a time sufficient to remove essentially all of said adhering oil, said aqueous solution consisting essentially of water and between about 0.05 and 0.25 percent of a non-ionic detergent selected from the class consisting (i) the condensation reaction product of tall oil and 15 moles of ethylene oxide per mole of said oil, (ii) the condensation product of diisobutylphenol and 9-10 moles of ethylene oxide per -mole of said phenol, and (iii) octylphenol with 7-8 moles .of ethylene oxide per mole of said phenol.

4.'The method of claim 1 wherein said detergent is octylphenol with 7-8 moles of ethylene oxide per mole of said phenol.

5. The method of claim 1 wherein said temperature is between about 170 F. and 200 F.

6. The process of claim 1 wherein said oil is crude oil.

7. The process of claim 1 wherein said oil is bunker fuel oil.

8. The process of claim 1 wherein said oil is kerosene.

9. The process of claim 1 wherein the oil-solution is passed to a settling zone wherein said solution is maintained for an averaged time of at least about 2 hours and an oil layer is separated from an aqueous phase which phase is disposable into bodies of water without pollution hazard.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Canada May 14, 1957 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No.. 2,952,571

September 13 1960 Arthur J. Freedman It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 47, after Yless contrary abilities."- insert the following paragraph:

Wherever the words "Butterworth or "Bu'tterworthing appear they are to be understood as used in the sense of 'Butterworth tank cleaning procedure.

Signed and sealed this 15th day of August 1961.

(SEAL) Attest:

ERNEST Wa SWIDER DAVID L LADD Attesting Officer Commissioner of Patents

Claims (1)

1. A METHOD OF CLEANING A TANKER COMPARTMENT TO REMOVE HYDROCARBON OIL ADHERING TO THE WALLS OF SAID COMPARTMENT, WHICH METHOD COMPRISES WASHING THE SURFACES IN SAID COMPARTMENT WITH AN AQUEOUS SOLUTION DIRECTED AGAINST SAID SURFACES AT A DISCHARGE PRESSURE OF BETWEEN ABOUT 100 AND 300 P.S.I.G. AND AT A DISCHARGE TEMPERATURE BETWEEN ABOUT 140*F. AND 200*F., FOR A TIME SUFFICIENT TO REMOVE ESSENTIALLY ALL OF SAID ADHERING OIL, SAID AQUEOUS SOLUTION CONSISTING ESSENTIALLY OF WATER AND BETWEEN ABOUT 0.05 AND 0.25 PERCENT OF A NON-IONIC DETERGENT SELECTED FROM THE CLASS CONSISTING (I) THE CONDENSATION REACTION PRODUCT OF TALL OIL AND 15 MOLES OF ETHYLENE OXIDE PER MOLE OF SAID OIL, (II) THE CONDENSATION PRODUCT OF DIISOBUTYLPHENOL, AND 9-10 MOLES OF ETHYLENE OXIDE PER MOLE OF SAID PHENOL, AND (III) OXTYLPHENOL WITH 7-8 MOLES OF ETHYLENE OXIDE PER MOLE OF SAID PHENOL AND REMOVING ADHERING AQUEOUS SOLUTION FROM SAID SURFACE BY RINSING WITH WATER, FREE OF DETERGENT.