RU2740121C2 - Method for washing oil-contaminated soils - Google Patents

Abstract

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: method can be used in flushing soils contaminated with oil products during normal operation of oil refining, petrochemical and oil producing enterprises, oil storage tanks and oil storages. Essence of invention consists in the fact that soil is washed with aqueous solution of surfactants using pressure and production wells, before injection into formation solution of surfactants is subjected to treatment with spark pulse high-voltage discharges with formation in solution of ozone and hydrogen peroxide, as well as pulsed hydraulic shocks, which are propagated in the formation with pumped solution, the solution is filtered in the formation in the electric field alternately in the direction of the electric field intensity vector and in the opposite direction, wherein electric field is directed perpendicularly to water flow, and nearby water flow is intercepted technogenic flow of ground water, which together with washing solution is directed to separation of flow into suspended substances, oil products and water. Oil products are dehydrated and utilized, and water is additionally filtered in coalescing charge, floated, then surfactant concentration is corrected, heated and pumped again into formation. Injection and production wells are arranged in alternating rows. 100 % solution is injected into the first row of injection wells, and in remaining injection wells - 20 % solution. 100 % solution is extracted from the last row of production wells, and 20 % of the solution is extracted from the remaining rows of production wells.

EFFECT: high efficiency of extracting petroleum products from technologically contaminated soils, high quality of reclaimed soils.

1 cl, 1 dwg, 2 tbl

Description

The invention relates to methods for flushing soils contaminated with oil products during the normal operation of oil refineries, petrochemical and oil production enterprises, oil depots, oil storage facilities.

A known method of processing oil sludge, including the separation of the aqueous phase and free hydrocarbons, mixing oil sludge with rock-forming, inoculating, catalytic and neutralizing additives, the formation of stacks, composting with aeration, blowing or stirring. The oil sludge is premixed with a surfactant solution at a temperature of 60-70 ° C, then washed. The resulting filtrate is defended, suspended solids are removed in the oil sludge, oil products are removed for disposal, the water-oil emulsion is filtered in a layer of hydrocarbon liquid, the surfactant concentration is adjusted, the surfactant solution is heated, mixed with the original oil sludge (RF Patent 2549657).

The disadvantage is the low efficiency of extracting oil products from technogenically contaminated soils.

A known method of cleaning oil-contaminated soils, grounds and oil sludge (RF patent No. 2244685). The method includes washing the soil (soil, sludge) with a washing liquid, regenerating the liquid by phase separation with separation of the organic phase and returning the aqueous phase to the cleaning cycle. Before washing, the soil is divided into a floating mass and a deposited soil, and then each separated fraction is washed. The floating mass is washed by blasting on a vibrating sieve with the simultaneous separation of the washed mass from the contaminated washing liquid. Washing of the deposited soil is carried out in three stages. At the first stage, washing is carried out during deposition in a stream of washing liquid, at the second stage, the material is jetted on an inclined screw conveyor while moving the material, at the third stage, washing is carried out by jetting on a vibrating sieve with simultaneous separation of the washed soil from the contaminated washing liquid. Regeneration of the washing liquid is carried out by means of gravity sediment. An aqueous detergent solution is used as a washing liquid, which forms an unstable emulsion with hydrocarbons and contains nonionic surfactants.

The disadvantage is the low efficiency of extracting oil products from technogenically contaminated soils.

The closest in technical essence and the achieved result is a method of flushing oil-contaminated soils with carbonated water using injection and production wells. After washing the soil, water is pumped out to the surface, sent to the settling system, purified, and re-injected into the reservoir (Safarov AM Assessment and technology for reducing the negative impact of large petrochemical complexes on the environment / Abstract of the thesis for the degree of Doctor of Technical Sciences. - Ufa. 2014. - 46 p.).

The disadvantage of the invention is the relatively low effect of extracting oil products from contaminated soils.

The objective of the invention is to improve the efficiency of extracting oil products from technogenically contaminated soils, improving the quality of recovered soils.

The essence of the invention lies in the fact that the soils are flushed using injection and production wells, the extracted solution is cleaned from suspended solids and oil products, the solution is re-injected into oil-contaminated soils, according to the invention, the soils are flushed with an aqueous surfactant solution, which is subjected to spark treatment before injection into the formation. by pulsed high-voltage discharges with the formation of ozone and hydrogen peroxide in the solution, as well as pulsed hydraulic shocks, which propagate in the reservoir with the injected solution, the solution is filtered in the reservoir in an electric field alternately in the direction of the electric field vector and in the opposite direction, and the electric field is directed perpendicularly the watercourse, and near the watercourse, the technogenic flow of groundwater is intercepted, which, together with the washing solution, is directed to separate the flow into suspended solids, oil products and water, and oil products about waterless and disposed of, and the water is additionally filtered in a coalescing charge, floated, then the surfactant concentration is corrected, heated and re-injected into the formation, and the injection and production wells are arranged in alternating rows, 100% solution is injected into the first row of injection wells, and the rest of the injection wells wells - 20% solution each, 100% solution is extracted from the last row of production wells, and 20% solution from the remaining rows of production wells.

The figure shows a complex for flushing oil-contaminated soils.

The figure shows an area 1 contaminated with oil products to a considerable depth, where technogenic flows of groundwater are formed, directed towards the watercourse 2. Near the watercourse 2, there is a collector for intercepting technogenic flows, which is a perforated pipe 3 placed in a trench 4.

In parallel to the watercourse in the contaminated area, alternating rows of 5 injection and 6 production wells are located. The distance between the rows of wells and between the wells in the rows is in the range of 50-100 m.The depth of the wells is determined by engineering surveys based on the spread of oil products and is 3-25 m.Perforated pipes of 5 injection wells and 6 production wells at the same time serve as electrodes, therefore made of electrically conductive materials. The pipes of the injection wells 5 are connected to the negative pole of the power supply 7, made of aluminum, the pipes of the production wells 6 are connected to the positive pole of the power supply 7, therefore, they must be insoluble during anodic polarization. It is proposed to make these pipes from a coke-oven composition (RF Patent No. 101443).

Washing solutions from production wells 6 and groundwater from a perforated pipe 3 are fed to the inlet of treatment facilities, consisting of a three-product hydrocyclone 8, a coalescing filter 9, a flotation device 10, a mixer 11 with a reagent facility 12, a heat exchanger 13, a pumping station 14, a plasma-chemical reactor 15 with a generator of 16 pulse voltages.

The lower outlet of the hydrocyclone 8 is connected to the slurry platform 17, the upper one is connected to the liquid hydrophobic filter 18 and the accumulator of oil products 19.

The method is carried out as follows.

In recent years, a new type of environmental damage has been discovered, consisting in the impregnation of soils with oil products near the operation of oil refineries, petrochemicals, oil production, etc. It has been established that soils are impregnated to a depth of 3 to 25 m, depending on the occurrence of water-resistant layers. Over the long years of the existence of the contaminated areas, technogenic flows of groundwater containing oil products have formed, directed to water bodies, as a rule, to watercourses. It has been established that man-made streams enter waterways due to infiltration, polluting water and bottom sediments.

The method consists in flushing the contaminated area (formation) with an aqueous solution of surface active substances (SAS) using intensification methods with subsequent separation of oil products from the washing solution.

Before injecting the surfactant solution into the formation, it is subjected to treatment with high-voltage pulsed spark discharges in a plasma-chemical reactor 15 with a 16 pulse voltage generator. The generator 16 generates pulses with a voltage of 110 kV with a duration of 1 μs with a repetition rate of 0.1 Hz. In the plasma-chemical reactor 15 spark discharges occur with the formation of high-temperature plasma, ultraviolet radiation, and hydraulic shocks. Under the action of spark shocks in the treated solution, strong oxidants are formed, such as ozone, hydrogen peroxide, atomic oxygen, which enhance the washing effect of the solution. However, the greatest effect is achieved due to hydraulic shocks, which propagate in the form of high pressure waves throughout the entire formation, enhancing the washing action of the solution due to mechanical action.

Then the solution is fed into the injection wells, filtered towards the production wells in the electric field created by the power source 7. The pipes of injection 5 and production 6 wells are at the same time cathodes and anodes, respectively. A voltage of about 4 V is applied to the electrodes from the power supply 7 V. At the anodes, gaseous oxygen and chlorine are formed, which are strong oxidants capable of oxidizing oil products to carbon dioxide and water. On the other hand, in an electric field, electrophoresis of emulsified droplets of petroleum products with a negative sign of charge occurs, which move in the direction of the vector of the electric field strength and are concentrated near the anode. Thus, part of the droplets of oil products is oxidized at the anode, and part is discharged through the production well 6.

It was found that when filtering water in the direction of the watercourse, the productivity of the rows of wells from 1 to 6 should be:

1 row of injection wells - 100%;

2nd row of production wells - 20%;

3 row of injection wells - 20%;

4th row of production wells - 20%;

5 row of injection wells - 20%;

6 row of production wells - 100%,

which will lead to the selection of the most contaminated part of the surfactant solution from the formation and a decrease in the load on the treatment facilities.

It is possible that a part of the technogenic flow will not be extracted by the production wells 6 and will be filtered in the formation towards the watercourse 2, then it will be extracted by the perforated pipe 3 of the interception collector and sent for joint treatment with the production of production wells 6 to a three-product pressure hydrocyclone 8, which separates the flow for suspended solids, oil products and water. Suspended substances are placed on the sludge site 17, where they are dehydrated and then disposed of. The watered oil products are directed to a liquid hydrophobic filter 18, where they are separated into dehydrated oil products entering the storage tank 19 and water entering the "head" of the treatment facilities.

The well products, preliminarily purified by hydrocyclone 8, are further purified by a coalescing filter 9 and a flotation device 10. The flotation foam is processed into a hydrophobic filter 18. Next, the surfactant concentration in mixer 11 is corrected using a reagent facility 12, heated in a heat exchanger 13 and pumped into the reservoir by a pumping station 14 through the plasma-chemical reactor 15. The cycle is repeated.

Example 1. Experiments were carried out on washing quartz sand of fraction 0.8-1.2 mm, containing 10 g / kg of commercial oil. The concentration of the surfactant type OP-10 was 5 g per 1 liter of tap water, the water temperature was 40 ° C. To activate the water, 2 electrodes were placed in the experimental cell: the anode from a coke oven, and the cathode from aluminum. A voltage of 4 V was applied to the electrodes. The filtration rate was varied in the range of 0.05-1.0 m / h.

The results of washing silica sand from oil with a surfactant solution with and without an electric field are shown in Table 1.

It follows from the above results that the effect of cleaning quartz sand from oil with an electric field is 13% higher than without a field. The optimum filtration rate should be considered 0.1 m / h, at which a relatively high sand cleaning effect is achieved.

Example 2. Experiments were carried out to wash off quartz sand of fraction 0.8-1.2 mm, containing 10 g / kg of commercial oil. The concentration of the surfactant type OP-10 was 5 g per 1 liter of tap water, the water temperature was 40 ° C. To activate the water, 2 electrodes were placed in the experimental cell: the anode from a coke oven, and the cathode from aluminum. A voltage of 4 V was applied to the electrodes. Water samples were taken from the anode region for analysis of oil products in an amount of 5–30%. The results are shown in Table 2.

It follows from the data presented that drops of oil products are concentrated near the anode, the concentration of which is higher than the background concentration in the flow. The optimal value is 20% of the liquid withdrawal from the anode zone.

The technical result is to increase the efficiency of extracting oil products from technogenically contaminated soils, improving the quality of recovered soils.

Claims (1)

A method for flushing oil-contaminated soils, including flushing soils using injection and production wells, cleaning the extracted solution from suspended solids and oil products, re-injecting the solution into oil-contaminated soils, characterized in that the soils are washed with an aqueous solution of surfactants (surfactant), which is before injection into the formation is subjected to treatment with high-voltage spark discharges with the formation of ozone and hydrogen peroxide in the solution, as well as pulsed hydraulic shocks, which are distributed in the formation with the injected solution, the solution is filtered in the formation in an electric field alternately in the direction of the electric field strength vector and in the opposite direction , moreover, the electric field is directed perpendicular to the watercourse, and near the watercourse, the technogenic flow of groundwater is intercepted, which, together with the washing solution, is directed to separate the flow into suspended solids, oil product s and water, and the oil products are dehydrated and disposed of, and the water is additionally filtered in a coalescing load, floated, then the surfactant concentration is corrected, heated and re-injected into the formation, and the injection and production wells are arranged in alternating rows, 100% is injected into the first row of injection wells solution, and in the remaining injection wells - 20% solution each, 100% solution is extracted from the last row of production wells, and 20% solution from the remaining rows of production wells.

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