RU2332359C1 - Method of purification of sewage water from crude oil and oil products - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to protection of environment, in particular, water basin, from pollution with crude oil and oil products and can be used for deep purification of water from crude oil and its regeneration, in the process of its extraction and transportation, its refining into oil products and their utilisation from industrial water sewage, as well as in liquidation of consequences of emergency situations, causing pollution of water reservoirs with crude oil and oil products. Purification of sewage water from crude oil and oil products is performed in continuous mode by passing through oil layer which consists of high-boiling oil fractions until volume ratio of oil to crude oil 1:20 is achieved. Aftertreatmet of water from crude oil to hygienic norms is achieved by passing it through sorptive filter.

EFFECT: simplification of process of water purification and increase of purification degree.

2 cl, 2 tbl

Description

The invention relates to the field of environmental protection, in particular the water basin, from pollution by oil (oil products) and can be used for deep purification of water from oil and its regeneration, during its production and transportation, oil processing into oil products and their utilization from industrial drains, as well as during the elimination of the consequences of emergency situations that cause water pollution with oil or oil products.

A known method of separating two immiscible liquids and a device for its implementation [1], where a mixture of oil and water is fed into a separation tank filled with water in the presence of a surface oil layer. Due to the design features and the location of the separation walls, this device allows you to separate oil from water and provide its residual concentration in water from 5 to 15 mg / l with an initial oil content of from 50 to 1500 mg / l.

The disadvantage of this method is that satisfactory results can only be obtained by cleaning certain types of oil and petroleum products that have minimal solubility in water and do not form stable emulsions with water. It is known [2] that the solubility of oil and oil products in water is (mg / l): 10-50 for oil, 9-505 for gasoline, 8-22 for diesel fuel (solar oil), 1780 for benzene, 515 for toluene, 175 for o-xylene. On the other hand, in water-oil mixtures containing various detergents and electrolytes, stable emulsions are always formed. Therefore, high-quality water purification from hydrocarbons in this way cannot be achieved. This is due to the fact that only floating oil is removed, and the dissolved and emulsified component of the pollution is not extracted. Thus, this method has a low degree of purification of water from oil.

The closest to the achieved results of oilfield wastewater treatment is the method [3], in which oilfield water is passed through an oil filter, sedimented in a tank and fed by gravity through a distributor to a solar filter, passing through which the water is refined and supplied through the pipeline to the consumer, for example for injection into reservoirs in order to maintain reservoir pressure. The residual oil content in purified water is 6–9 mg / l. The disadvantages of this method are its imperfect technology, namely its multi-stage operation in periodic mode and the use of solar oil as a hydrocarbon filter.

Hydrochloric oil is a product of fractional distillation of oil in the temperature range from 250 to 400 ° C, with a density of 0.88-0.91, and whose chemical composition depends on the nature of the initial oil, and the aromatic hydrocarbon content can reach 30% [4]. It is known that the solubility of oil products in water increases in the series paraffins - cycloparaffins - aromatic hydrocarbons, and the solubility of solar oil in water can reach 22 mg / l [2]. Consequently, the use of filters based on oil and solar oil cannot provide high-quality wastewater treatment, especially if they contain aromatic and cycloparaffin hydrocarbons.

The residual content of petroleum products in water, as indicated in the prototype 6-9 mg / l, can be achieved only when using special high-temperature fractions of hydrochloric oil.

When refining petroleum or petroleum products rich in aromatic and cycloparaffin hydrocarbons, mixtures of hydrochloric oil with oil will be formed, which are highly soluble in water. As a result, the residual oil content in purified water will increase even more. Therefore, this method cannot be recommended for wastewater treatment from oil products.

Therefore, this method [3] of water purification does not allow reaching hygienic standards, and the authors recommend using the obtained water for injection into productive formations in order to maintain reservoir pressure.

The objective of the invention is to simplify the process and increase the degree of purification of oil-contaminated waters.

The technical result - the implementation of the cleaning process in one stage, in a continuous mode, water purification to established hygienic standards.

This is achieved by the fact that the wastewater is cleaned of oil and oil products in a continuous mode by passing through an oil layer consisting of high boiling oil fractions (hereinafter referred to as oil) until the volumetric oil to oil ratios of 1:20 are reached. Post-treatment of water from oil to hygiene standards is carried out by passing it through a sorption filter.

The method allows to clean oil-contaminated water to the required hygienic standards in a continuous mode with minimum oil consumption. Moreover, more than 99% of the oil contained in the treated water is retained in the hydrophobic filter, which reduces the load on the sorbents.

Such a sequence of water treatment procedures allows quantitatively regenerating oil and oil products, increasing the service life of sorbents and reducing the cost of the water treatment process.

In this case, additional water treatment is not required, and it can be discharged into water bodies or used for its intended purpose.

Example 1. Wastewater with an oil content of 5300 mg / l is supplied to an oil layer 30 mm thick. Purified water contains 2 mg / l of oil. For purification to hygiene standards, water passes through a sorption filter. The oil content in water after sorption purification is 0.05 mg / L.

When sewage passes through a hydrophobic filter, oil is trapped in the oil. When the oil-oil layer reaches a thickness of 600 mm, it is removed, a new portion of oil is loaded and the water purification process is carried out as described above.

The recovered oil layer containing 5% oil by volume is returned to the oil pipe or used for its intended purpose.

A sorption filter filled with an oil sorbent must be replaced when an oil leak occurs at the outlet.

The results of experimental studies when testing a known method of purification of oil wastewater and the proposed are shown in tables 1 and 2, respectively.

Table 1 The parameters of the wastewater treatment process containing 5300 mg / l of oil, according to the prototype method Example No. The height of the oil filter layer, mm The residual oil content in the treated wastewater after filtering it through a layer of oil, mg / l The height of the layer of solar oil, mm The ratio of the volume of solar oil to the volume of oil caught The residual oil content in the treated wastewater after filtering it through a layer of solar oil, m / hl 2 500 127 fifty 1-0 6.0 3 500 140 fifty 1: 0.16 8.0 four 500 150 fifty 1: 0.33 7.0 5 500 130 fifty 1: 0.66 9.0 6 500 141 fifty 1: 1.0 8.0 7 500 146 fifty 1: 1.33 7.0 8 500 138 fifty 1: 1.66 9.0 9 500 157 fifty 1: 3.33 52.0 10 500 162 fifty 1: 6.66 80.0 eleven 500 155 fifty 1:10 112.0

table 2 The process parameters of wastewater treatment containing 5300 mg / l of oil, according to the proposed method Example No. Height of oil filtering layer, mm The ratio of the oil layer to the caught oil The residual oil content in the treated wastewater, mg / l Oil After oil sorbent 2 thirty 1-0 2.0 0,03 3 thirty 1: 0.16 2.0 0,03 four thirty 1: 0.33 2.1 0,03 5 thirty 1: 0.66 2.1 0,03 6 thirty 1: 1,0 2.2 0,03 7 thirty 1: 1.33 2.2 0.04 8 thirty 1: 1.66 2.2 0,03 9 thirty 1: 3.33 2,5 0.04 10 thirty 1: 6.66 2.7 0.04 eleven thirty 1:10 3.0 0.05 12 thirty 1:20 4.0 0.05

From the data of tables 1 and 2 it can be seen that in the prototype, when the ratio of solar oil to oil is 1: 1.66 (example 8), the oil content in water increases by 1.5 times compared to the background solution (example 2), whereas in the proposed 1.1 times. When the ratio of 1:10 (example 11) in the prototype, the oil content increases by 18.5 times, while in the proposed 1.5 times, and when the ratio of the oil / oil layer increases to 1:20 (example 12), the oil content increases in 2 times from the original (this range is not in the prototype).

Thus, the hydrophobic filter, even with an oil to oil ratio of 1:20 (example 12), allows you to purify water 1.5 times more efficiently than the background solution in the prototype (example 2).

The proposed method can be applied for deep purification of water from oil and its regeneration, during its production and transportation, oil refining into oil products and their utilization from industrial drains, as well as in eliminating the consequences of emergencies that cause water pollution with oil or oil products.

List of sources used

1. Patent No. 1805991 A3, B01D 17/02, 1991

2. Karyakin A.V., Gribovskaya I.F. Optical spectroscopy and luminescence methods in the analysis of natural and waste waters. - M .: Chemistry, 1987 .-- 304 p.

3. Copyright certificate No. 1754666 A1, С02F 1/58, 1992

4. Brief chemical encyclopedia. Ed. count. ed. I.L. Knunyants, Volume 4 - M.: Soviet Encyclopedia, 1965.

Claims (2)

1. The method of purification of wastewater from oil and oil products, comprising filtering water through a layer of oil, characterized in that the treatment is carried out in continuous mode, passing contaminated water through an oil layer consisting of high boiling fractions of oil, to achieve volumetric ratios of oil to oil 1: twenty. 2. The method according to claim 1, characterized in that the post-treatment of water from oil to hygiene standards is carried out by passing it through a sorption filter.