RU2165318C1 - Method of cleaning surfaces to remove liquid hydrocarbons - Google Patents

Abstract

FIELD: oil pollution removal. SUBSTANCE: cleaning is effected by detergent composition containing, wt %: one or several surfactants 5.0-12.0, electrolyte 1.0-8.0, and soda ash Ц to 100 or composition with the same components wherein 2.0-8.0 of soda ash is substituted by corrosion inhibitor. Detergent composition is prepared by dissolving detergent in water preheated to 20-65 C to concentration 1.0-3.5% and keeping this temperature during cleaning process followed by pumping out detergent solution with removed hydrocarbons into the same tank, from which detergent solution is transferred into cleaning zone. Detergent-hydrocarbon mixture is then settled in the same tank. EFFECT: enhanced cleaning efficiency and reduced process cost and cleaning time. 3 ex

Description

 The claimed invention relates to a technology for cleaning (washing, degreasing) surfaces from residues of liquid hydrocarbons (oil and products of its processing - fuel oil, diesel fuel, oils, lubricants, as well as vegetable and animal oils and fats) and can be used in various industries for cleaning and degreasing of tanks, containers, parts, components, mechanisms, equipment, etc. while ensuring their corrosion protection.

 An urgent problem of the technology of cleaning surfaces from liquid hydrocarbons is to reduce the cost of cleaning while ensuring high quality cleaning, high environmental friendliness and fire safety, as well as improving working conditions for workers. Existing cleaning methods do not fully meet these requirements. The reason for this is the complexity and incomplete study of the physicochemical processes that occur during cleaning of surfaces from liquid hydrocarbons, the results of which are influenced by a complex of factors: surface material, composition and properties of contaminants, modes of the cleaning process, properties of detergents, changes in these properties and mode parameters during the process, especially the interaction of washing solutions with contaminants, etc.

 Known methods for cleaning surfaces from liquid hydrocarbons using solvents: acetone, kerosene, white spirit, etc. (see, for example, [1-4]). The main operations of these methods include washing the surface to be cleaned, pumping out the resulting emulsion of the solvent and liquid hydrocarbons and removing it with a drain to the treatment plant.

 The main disadvantages of using various types of solvents as washing liquids include: high fire hazard, environmental hazard, high cost of technological processes. Known solvents with a high flash point (such as trichlorethylene or trichloroethane), which do not pose a fire hazard, are extremely toxic and very dangerous to health.

 There are also known methods of cleaning surfaces from liquid hydrocarbons with detergent solutions based on a surfactant and an electrolyte [5-8]. In accordance with these methods, the surface to be cleaned is subjected to jet washing with a heated washing solution, the mixture of the washing solution with washed liquid hydrocarbons is pumped out of the cleaning zone and settled in the tank, after which the washed hydrocarbons are removed for regeneration. Due to the provision of recirculation of the washing solution, these methods do not require the discharge of the solution to the treatment plant. Their main disadvantages are the high cost, the relatively long duration of the cleaning process, the complexity of the necessary technological equipment.

 Closest to the claimed technical essence and combination of essential features is the method according to the invention [8], adopted as a prototype. This method involves the use of soda ash, surfactant, electrolyte, antifoam as the main components of the detergent. The surface to be cleaned is washed with jets of the heated detergent solution, the spent washing solution is partially cleaned, then it is divided into two volumes, in one of which the washing solution is heated, and in the other, a sedimentation regime is created with the continuous removal of the pop-up impurities from it for the subsequent regeneration of the separated liquid hydrocarbons.

 The disadvantages of the prototype method include the high cost, the presence of two stages of cleaning the solution, the relatively large duration of the cleaning process, the complexity of the processing equipment required to implement the method.

 The objective of the invention is to reduce the cost and duration of the cleaning process while ensuring high quality cleaning.

This problem is solved in that in a method for cleaning surfaces from liquid hydrocarbons using a detergent containing a surfactant, an electrolyte and soda ash, including preparing a washing solution with heating it, washing the surface to be cleaned with a washing solution, pumping a mixture of the washing solution and the washed liquid hydrocarbons from the zone washing, sedimenting this mixture in the tank and removing the washed liquid hydrocarbons, the detergent has a composition containing, wt.%: one or more nonionic surfactants - 5.0 - 12.0, electrolyte - 1.0 - 6.0 and ka tsinirovannuyu soda - 100.0 or composition with these components with the substitution of 2.0 -. 8.0 wt% soda ash corrosion inhibitor, a detergent solution is prepared by dissolving the detergent is heated to 20 - 65 ^o C water to the creation of detergent concentration in the solution from 1.0 to 3.5%, the temperature of the washing solution is maintained in the range of 20 to 65 ^° C. by heating it, the mixture of the washing solution and the washed liquid hydrocarbons is pumped into the same tank from which the washing solution is supplied to the washing zone, and in the same tank carry out oh laundered hydrocarbons.

 The technical result of the invention in comparison with the prototype is to reduce the cost of cleaning, reducing its duration, reducing the number of technological operations, simplifying process equipment, saving energy costs.

 The achievement of the specified technical result is determined by several factors. As studies have shown, the detergent composition experimentally found by the authors prevents the formation of water-in-oil inverse emulsions. At the same time, direct emulsions are formed and exist in the washing solution for a short time, undergoing rapid demulsification. Thanks to the action of these mechanisms, a high quality of cleaning surfaces, increasing its speed, reducing sludge time, "self-cleaning" of the washing solution, increasing the frequency of its use and a high degree of purity of the washed liquid hydrocarbons is achieved, as a result of which there is no need for special regeneration. The water content in the washed hydrocarbons does not exceed 5%, and they can be used for their intended purpose without further processing. The processes of washing surfaces, pumping a mixture of washing solution and washed hydrocarbons and its sedimentation go simultaneously in a closed cycle and require the use of one tank for these purposes. However, the proposed method eliminates the need for introducing antifoam agents into the composition of the washing solution, and provides the possibility of anticorrosive protection of the surface being cleaned. Ultimately, there is a reduction in energy costs and the cost of cleaning. The cost of cleaning is also reduced due to the high content of soda ash in the detergent, which is a cheap product. In mass production, the cost of detergent will be approximately no more than 1.0 cu for 1 kg.

The cleaning time, depending on the surface material, degree and type of contamination, is from 3 minutes to 15 minutes, the heat consumption per 1 m ^{3 of the} solution is 0.04 cal / h, the detergent consumption is 0.004 kg / m ² .

 As an electrolyte in a detergent, for example, a uniflock, saponified acrylic acid nitrides and other electrolytes and polyelectrolytes can be used. The electrolyte, on the one hand, intensifies physicochemical processes, in particular, the action of surfactants, and on the other hand, provides demulsification of washed hydrocarbons. When the electrolyte content in the detergent is less than 1.0 wt.%, The speed of the cleaning process slows down, demulsification is weakened. An increase in the electrolyte content in excess of 6.0 wt.% Prevents the "cleavage" of liquid hydrocarbons from the surface being cleaned and the formation of an emulsion and as a result negatively affects both the speed of the cleaning process and the cleaning efficiency as a whole.

 As a surfactant in a detergent, for example, neonol, lutensol, syntanol or several surfactants can be used. When the surfactant content in the detergent is less than 5 wt. % it is difficult to "split off" liquid hydrocarbons from the surface being cleaned, the speed of the cleaning process is slowed down. If the surfactant content in the detergent exceeds 12 wt.%, Foaming with its negative consequences takes place.

 When the content of soda ash in the detergent is less than 82 wt.%, The washing properties of the solution deteriorate, the cost of the detergent increases.

To impart anti-corrosion properties to the surfaces to be cleaned and to facilitate subsequent cleaning of these surfaces, 2.0 to 8.0 wt.% Of a corrosion inhibitor is introduced into the detergent composition. As such a component can serve, for example, nine-sodium sodium metasilicate Na ₂ SiO ₃ · 9H ₂ O. The content of the corrosion inhibitor of less than 2.0 wt.% Does not provide a strong anti-corrosion layer. Excess corrosion inhibitor 8.0 wt.% Negatively affects the cleaning process.

A washing solution is prepared by portionwise dissolving the detergent powder in water heated to 20-60 ^° C, with thorough mixing of the solution by known methods (stirrer, bubbling with compressed air, etc.). During the cleaning process, the temperature of the solution is maintained in the above range by heating.

 The concentration of detergent in the solution, depending on specific cases, is from 1.0 to 3.5%. At a concentration of less than 1.0%, the speed of the cleaning process is low, and its duration increases. Concentrations above 3.5% adversely affect the working conditions of workers, activate corrosion of metal parts of technological equipment.

At a temperature of the washing solution below 20 ^o C the cleaning process is lengthy. If this temperature exceeds 65 ^o C, the cleaning process becomes not very effective due to the fact that part of the surfactant precipitates and does not participate in the cleaning process. In addition, the decomposition of the solution begins with the release of carbon dioxide and the activation of foaming. At temperatures above 70 ^o C, the washing properties of the solution practically disappear.

 The "depletion" of the solution is controlled by its total alkalinity (see table) by titration and the concentration of the solution is adjusted according to the results of the control. The pH of the solution should be between 9 and 12.

 The invention is illustrated by the following examples of implementation of the proposed method (see table).

 Example 1. Cleaning surfaces of steel and cast iron.

35 kg of detergent containing, wt.%: 2.7 uniflok, 7.3 neonol and 90.0 soda ash, was dissolved in 1000 l of water with a temperature of 50 ^o C in the tank by means of batch mixing. The solution was then heated to a temperature of 60 ^° C., this temperature was maintained and, using a pump, it was fed into a jet washing head to clean the tank with a capacity of 60 m ³ of residual fuel oil. The mixture of washing solution and washed hydrocarbons formed during jet washing was pumped into a tank with a washing solution. Washed fuel oil was pumped into a separate container. The duration of the cleaning process was 25 minutes, the water content in the washed product was less than 4.5%.

 Example 2. Cleaning surfaces from non-ferrous metals.

20 kg of detergent with the composition shown in example 1 was dissolved in 1000 l of water heated to 50 ^o C, followed by stirring and heating the solution to 55 ^o C. Similarly to example 1, the tank was cleaned from brass with a capacity of 5 m ³ from the remnants of plums machine oils. The duration of the cleaning process was less than 7 minutes, the water cut of the washed products was less than 2%.

 Example 3. Cleaning the axle boxes of refractory graphite lubricant.

The axle boxes were placed in a bath with a capacity of 1500 m ³ . The detergent contained neonol and lutensol (in total 7 wt.%), As well as 2.4 wt.% Uniflock and 90.6 wt.% Soda ash as a surfactant. The washing solution had a concentration of 3.0%, an operating temperature of 65 ^° C. The solution was supplied to the axle boxes using a nozzle. The cleaning time depended on the degree of contamination, but in all cases did not exceed 10 minutes.

 The proposed method was tested in the depot of the October railway in experimental facilities containing standard components and mechanisms. The results of the experimental verification, reflected in the above examples, indicate the possibility of industrial implementation of the claimed invention.

 The proposed method can find application for washing not only metal surfaces, but also surfaces of glass, concrete, natural stones, tiles and some other materials.

Literature
1. Gurvich L. M. et al. The use of detergents when cleaning tractors, cars and agricultural machines. M., 1971, p. 22.

 2. A.S. USSR N 1013003, class B 08 B 9/08, publ. 04/23/83.

 3. A.S. USSR N 1147464, class B 08 B 9/08, publ. 03/30/85.

 4. A.S. USSR N 1219177, class B 08 B 3/08, publ. 03/23/86.

 5. A.S. USSR N 342692, class B 08 B 9/08, publ. 07/13/82.

 6. A.S. USSR N 944685, cl. B 08 B 3/08, publ. 07/28/82.

 7. Gurvich L.M. Recommendations for the use of new means of cleaning machines and parts for repair. M., 1975, p. 44, 72.

 8. A.S. USSR N 1597240, class B 08 B 3/02, publ. 10/07/90.

Claims (1)

A method of cleaning surfaces from liquid hydrocarbons using a detergent containing a surfactant, an electrolyte and soda ash, including preparing a washing solution with heating it, washing the surface to be cleaned with a washing solution, pumping a mixture of the washing solution and the washed liquid hydrocarbons from the washing zone, this sediment mixtures in the tank and the removal of liquid hydrocarbons, characterized in that the detergent has a composition containing, wt.%: one or more nonionic surfactants substances 5.0-12.0, electrolyte 1.0-6.0 and soda ash up to 100.0, or a composition with the indicated components with substitution of 2.0-8.0 wt.% soda ash with a corrosion inhibitor, a washing solution is prepared dissolving the detergent in water heated to 20-65 ^° C with a detergent concentration in the solution of 1.0-3.5%; maintain the temperature of the washing solution in the range of 20-65 ^° C by heating the solution; the mixture of the washing solution and washed liquid hydrocarbons is pumped into the same tank from which the washing solution is fed into the washing zone, and in the same tank e performed washed sludge hydrocarbons.

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