RU2176936C1 - Mechanothermochemical cleaning of objects from hydrocarbon contaminations - Google Patents

Abstract

FIELD: washing of transportation and process vessels, parts and units of mechanisms, ground from such contaminants as oil products, lubricants, fats and oil. SUBSTANCE: method is realized by closed cycle with aqueous solution of detergent forming unstable emulsion with hydrocarbon contaminants. Method includes stage of object washing and stage of regeneration of washing solution by phase separation of emulsion with subsequent separation of phases and return of aqueous washing solution to cleaning cycle. Detergent is used in the form of substance based on modified sodium salt of polyacrylic acid. Cleaning of object is effected in three stages. The first stage, before object cleaning, covers sampling of contaminant for determination of character and quantity of contaminants to select cleaning process parameters. The second stage includes heating of washing solution to temperature of 45-55 C and its supply at pressure of 1.0-1.5 MPa with the help of washing plant to provide for mechanical cleaning of surface contaminants and subsequent treatment for 5-30 min depending on character of contamination. The third stage includes regeneration of washing solution by separation of formed mixture into three phases: organic, aqueous and solid contaminants with subsequent monitoring of components content in solution and correction of their concentration automatically following the linear law up to required values before solution return to cleaning cycle. EFFECT: higher quality of cleaning, stable process of cleaning and reduced its duration. 2 cl, 2 tbl

Description

 The invention relates to the cleaning of objects from hydrocarbon contaminants, such as petroleum products, lubricants, fats and oils, and can be used, for example, for washing transport and technological tanks, parts and components of mechanisms, soil.

 A known method of thermochemical purification of containers from oil products according to the patent of the Russian Federation N 2106211, B 08 B 9/08, in which the cleaning is carried out using a mixture of organic solvents, and as a mixture of organic solvents use an aqueous solution of a nitrogen-containing reducing salt and a nitrogen-containing oxidizing salt obtained wherein the oil phase is removed by introducing a sufficient amount of industrial water.

 The considered method allows you to effectively remove oil and grease contaminants from the surface of the containers, however, the use of two liquids for cleaning complicates the process, the one-time use of solvents does not allow it to conduct in a closed cycle and leads to environmental pollution.

 The well-known "Method of cleaning the surface from hydrocarbon contamination", RF patent N 2135304, B 08 B 3/08, BI N 24, 08/27/1999, which is selected by the authors for the prototype.

 In this method, surface cleaning is carried out in a closed cycle with an aqueous solution of detergent capable of emulsifying hydrocarbon contaminants. The stage of regeneration of the washing solution is carried out by phase separation of the emulsion, followed by separation of the organic phase and the return of the aqueous phase to the cleaning cycle. As a washing solution, a solution is used that forms an unstable emulsion with hydrocarbon contaminants, containing polyelectrolyte and detergent additives, phase separation of the emulsion is carried out by gravitational sludge, while during the cleaning process they provide a volume ratio of organic pollution and washing solution of at least 1 to 2.

 In this method, a high degree of surface cleaning and the possibility of reuse of the washing solution after demulsification is provided, however, this technology is not effective, since its implementation does not take into account the nature of contamination of washing objects, mechanical impurities that got there during washing are not removed from the contaminated washing liquid, the activity of the washing solution is not controlled when it is returned to the cleaning cycle, which reduces the stability of the process, and the possibility of intensification of otsessa wash solution due to the thermal treatment.

 The objective of the proposed method is to improve the quality of cleaning, stability of the cleaning process, reducing its duration.

 The essence of the invention lies in the fact that in the method of mechano-thermochemical purification of objects from hydrocarbon contamination in a closed cycle with an aqueous solution of detergent, forming an unstable emulsion with hydrocarbon contaminants, comprising the stage of washing the object and the stage of regeneration of the washing solution by phase separation of the emulsion followed by phase separation and by returning the aqueous washing solution to the cleaning cycle, it is proposed according to the invention to clean objects in three stages, and in the first stage Ed washing the object, they take pollution samples, analyze them and select the technological parameters of cleaning, at the second stage of washing the object, they heat-treat the detergent solution, supply it under pressure to ensure mechanical cleaning of surface contaminants and then treat the object to be cleaned with a washing solution, at the third stage of regeneration a washing solution, the resulting mixture is divided into three phases: organic, aqueous and solid impurities, followed by monitoring the content of components in astvore and their concentration adjusted to desired values before returning to the cleaning cycle.

In addition, according to the method, as a detergent, a substance based on a modified polyacrylic acid sodium salt is used,
- heat treatment of the detergent solution is carried out at a temperature of 45-55 ^o C,
- the supply of the solution is carried out under a pressure of 1.0-1.5 MPa using a washing installation
- the treatment of the cleaned object in the washing solution is carried out depending on the type of contamination for 5-30 minutes,
- the separation of the resulting mixture is carried out in three stages, and in the first stage using a dirt trap, in the second - a gravity sump, and in the third - a coalescent oil separator,
- control is carried out using sampling and subsequent measurement of the concentration of TMS in the solution by its alkalinity,
- the addition of detergent is carried out automatically according to a linear law.

 The use of the three-stage washing technology in the proposed method will make it possible to differentiate the washing process for different objects, optimize it by using previously obtained information about the nature and amount of contaminants, and apply rationally selected washing parameters at subsequent stages, which will reduce production costs. The used parameters of the heat treatment of the solution can increase the efficiency of its washing action and at the same time do not contribute to an increase in the activity of hydrophobic components of contaminants. The separation of the solution into three phases allows you to utilize the organic phase (oil, oil products), highlight the mechanical impurities that reduce the cleaning efficiency and organize the recycling of the washing solution. The mechanical impurities in the washing solution cause clogging of the jet-forming nozzles, wear of the parts of the pumping pumps, re-contamination of the washed objects, excessive heat consumption for heating the solution by 20-40% due to the formation of deposits on the tubes of the heat exchangers. To ensure the stability of the process, it is necessary to constantly monitor the washing activity of the solution, for which constant or periodic monitoring of the concentration of the components of the washing solution is carried out and its adjustment to the required values. Thus, synchronization of the action of physicochemical, mechanical and thermal factors, the use of additive and synergistic effects in the washing action will increase the efficiency of this process.

 As a detergent, for example, a detergent based on a modified sodium salt of polyacrylic acid (UBON-D) can be used.

 The method is as follows.

 To clean the surface of hydrocarbon contaminants using a solution of detergent, forming an aggregative and sedimentation-unstable emulsion with hydrocarbon contaminants.

где R - радиус котла цистерны, м; L - длина цилиндрической части котла цистерны, м; φ₁, φ₂ - центральные углы, охватывающие дуги сегментов, заполненных мазутом, в сечениях соответственно у торца цистерны и сливного прибора, град.Before the start of the cleaning process, the nature and amount of contaminants to be removed from the facility is evaluated analytically or heuristically. The mass of the residue was determined by measuring the width of the strip of residue at one of the ends and at the drain device of the tank and calculated the balance by the formula:

where R is the radius of the boiler tank, m; L is the length of the cylindrical part of the boiler tank, m; φ ₁ , φ ₂ - central angles covering the arcs of segments filled with fuel oil, in sections, respectively, at the end of the tank and the drain device, deg.

 The brand of fuel oil was determined by pour point and viscosity.

 The degree of polymerization of oil products on the surface was determined by the dependence of the concentration of oil contained in the washing liquid flowing out of the tank on the washing time (τ). Based on this information, using the empirical database (the fragment is presented in table 1), the required amount and temperature of the washing solution, the concentration of components in it, its flow rate (or pressure) when feeding the object through a washing installation are determined.

 These parameters are implemented in the second stage of washing when the washing solution is supplied to the object.

 The solution with organic substances emulsified in it and mechanical impurities is discharged into the sump. In it, under the influence of gravitational forces, the contaminated liquid composition is divided into three phases - organic, aqueous and mechanical impurities.

 The gravitational separation process can be intensified if necessary through the use of appropriate equipment (for example, a hydrocyclone or separator). Next, the aqueous solution of the detergent to be regenerated is transported to the storage tank, where, after appropriate analyzes, the content of the components in it is adjusted and, if necessary, it is sent back to the washing cycle.

 The concentration of a technical detergent solution (TMS) is determined by its total alkalinity by the method of titration with hydrochloric acid with an indicator of methyl orange. For this, 25 ml of the filtered solution of TMS "UBON-D" is taken with a pipette or volumetric flask into a 250 ml conical flask, 3-4 drops of methyl orange indicator are added and titrated with 1 N (single-normal) HCl solution until a pink-orange color appears.

Total alkalinity (X) in% is calculated by the formula:
X = (0,053 • A • K • 100) / 25,
where 0,053 is the titer of a 1 N HCl solution of Na ₂ CO ₃ ;
K - correction to 1 N HCl solution;
A is the amount of 1 N HCl solution used for titration, ml;
25 - the amount of solution taken for analysis, ml.

 Sludge from the bottom of the sump is periodically removed by means of a hydraulic elevator.

 Examples of the method.

 Example 1

 They cleaned the inner surface of the railway tank contaminated with fuel oil.

 For cleaning, a solution of UBON-D was used.

The volume of fuel oil was 1.5-2 m ³ .

 Fuel oil grade - 100.

The temperature inside the tank is 0 ^o C.

For washing, 8 m ³ of UBON-D solution with a concentration of 3% was used, the temperature of the solution was 45 ^o C, and the supply pressure to the washing machine was 1.05 MPa.

 The cycle time was 16 minutes.

 The regenerated solution was collected in a buffer tank for processing the next tank.

 Studies of the oil product collected in the drive have shown that it meets the requirements of regulatory documents and can be used for its intended purpose.

Claims (2)

1. A method for mechanothermochemical cleaning of objects from hydrocarbon contamination in a closed cycle with an aqueous solution of a detergent, forming an unstable emulsion with hydrocarbon contaminants, including the stage of washing the object and the stage of regeneration of the washing solution by phase separation of the emulsion followed by phase separation and the return of the aqueous washing solution to the cleaning cycle, characterized in that as a detergent, a substance based on a modified sodium salt of polyacrylic acid is used; objects is carried out in three stages, wherein in the first step is carried out before cleaning the object sampling contaminants establish their nature and quantity, depending on which selects purification process parameters, in a second step a thermal treatment is carried object detergent cleaning solution at a temperature of 45-55 ^o C. , feeding it under a pressure of 1.0-1.5 MPa using a washing unit to ensure mechanical cleaning of surface contaminants and subsequent processing of the object to be cleaned with a washing solution depending on x contaminants for 5-30 minutes, at the third stage of the regeneration of the washing solution, the resulting mixture is divided into three phases: organic, aqueous and solid impurities, followed by monitoring the content of components in the solution and adjusting their concentration in an automatic mode according to the linear law to the required values before return to the cleaning cycle.  2. The method according to claim 1, characterized in that the separation of the resulting mixture is carried out in three stages, a dirt trap is used in the first stage, a gravity settler in the second, and a coalescent oil separator in the third.

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