RU2740500C1 - Method of oil purification from organochlorine compounds - Google Patents

Abstract

FIELD: oil, gas and coke-chemical industries.SUBSTANCE: invention relates to a method of cleaning oil from organochlorine compounds and can be used in oil industry. Invention relates to a method of cleaning oil from organochloride compounds involving mixing oil with a demulsifier, adding to the mixture a washing solution containing an alkali and a neutraliser, with subsequent separation of oil and water under the effect of temperature 135−150 °C and electric field in the electric dehydrator. Neutraliser used is stripped acid water from process plants of the oil refinery with its content in the washing solution of 98.14−99.5 wt. %.EFFECT: technical result is removal of organochlorine compounds from crude oil to a level of not more than 0.0003 wt%.1 cl, 9 ex

Description

The invention relates to a method for purifying oil from organochlorine compounds and can be used in the oil industry.

A known method of purification of hydrocarbon raw materials from organic chlorides (patent US 4721824, publ. 03/12/1987), based on the passage of raw materials over a special substrate having a catalytic protected layer containing shaped particles of bound magnesium oxide, inert with respect to the raw material. The disadvantage of this method is that it is applicable only to pure hydrocarbons such as toluene. When applied to crude oil, in addition to organochlorine compounds, oil components will also be adsorbed on the substrate.

A known method of purification of hydrocarbon raw materials from organic chlorides (US2012019090, publ. 24.06.2011), based on adsorption on molecular sieves. The disadvantage of this method is also its application only to pure hydrocarbons. When using the known method for the purification of crude oil, in addition to organochlorine compounds, oil components will also be adsorbed, which leads to a deterioration in the quality of the oil. Also, for the implementation of this known method, the construction of an additional technological unit is required.

There is a known method for reducing the content of organic chlorides in oil (RF patent 2605601, publ. 27.12.2016), including preliminary dehydration and degassing of oil, heating oil with the release of organic chlorides, removal of refined oil, while preliminary dehydration is performed until the water content in oil is not more than one %. Heating is carried out to a temperature that allows distilling a fraction containing organic chlorides and boiling at atmospheric pressure in the temperature range from the beginning of boiling to 204 ° C from the oil in a distillation column. The known method makes it possible to obtain refined oil with an organic chloride content of less than 10 ppm. However, when implementing this method, the released hydrogen chloride negatively affects the technological equipment, rendering it unusable, which in general makes the known method ineffective.

There is a known method for reducing the content of organic chlorides in oil (RF patent 2672263, publ. 11/13/2018), including settling and preliminary dehydration of oil when heated, processing oil with an alkali solution when heated, settling a mixture of oil and an alkali solution, removing the spent alkali solution and removing the purified oil. At the same time, for preliminary oil dehydration, oil is circulated with heating, after heating, a demulsifier is supplied to the oil, a mixture of oil with a demulsifier is circulated for at least one hour, after which it is defended for at least two hours, separated water is removed, the circulation is resumed, and oil is circulated 10-20% aqueous solution of sodium or potassium hydroxide with a dosage of 20-30% for oil, a mixture of oil and an aqueous solution of sodium or potassium hydroxide is heated to a temperature of 190-200 ° C while maintaining an excess pressure of at least 1.6 MPa for 6 hours, then the mixture of oil and an aqueous solution of sodium or potassium hydroxide is kept for 6 hours, depending on their structure, the cycles of oil processing with an aqueous solution of sodium or potassium hydroxide are repeated at a temperature of 220-230 ° C and an overpressure of at least 2.8 MPa for oil not containing volatile organochlorine compounds of aromatic structure, up to the value of the mass fraction of organic chlorides no more e 10 million ^-1 and oil containing volatile organochlorine compounds of aromatic structure, to a value of mass fraction of organic chlorides of no more than 100 million ^-1. The disadvantage of this method is its multistage and complexity.

There is a known method of removing chlorine-containing compounds from oil (RF patent 2065477, publ. 19.11.1993), according to which the oil is washed with water and an aqueous solution of alkali in an electric desalting unit in several stages at elevated temperatures. Washing with an aqueous solution of alkali is carried out at a temperature 30-80 ^o C higher than the previous washing with water. The disadvantages of this method are the high residual content of total chlorine in the oil (70 mg / l).

There is a known method for removing organochlorine compounds from oil (Chinese patent 102127464, publ. 22.10.2009), including mixing a demulsifier, a basic compound - an organic amine and an inorganic base, an interfacial transfer agent, which is one or more compounds of a quaternary ammonium salt, compounds of a quaternary salt phosphine and crown ethers, water and oil; with the subsequent separation of oil and water under the influence of heat and / or electric field. The known method is laborious and costly.

The closest to the claimed method in technical essence and the achieved result is the method described in the Chinese patent 101851528 (publ. 03/31/2009) "Method for deep desalting of hydrocarbon oil", selected as a prototype.

The known method includes mixing demulsifier and oil, adding to the mixture a washing solution containing an inorganic base and a neutralizer, followed by separation of oil and water under the action of heat and / or an electric field; in this case, the neutralizer is an organic amine with its content in the washing solution from 10 to 80 wt%. The known method makes it possible to purify oil from organochlorine compounds to a level of 0.0015 wt.%. However, the use of an organic amine in the process makes the process expensive and the resulting purified product is expensive. In addition, the organic amine used in the known method additionally contaminates the product to be purified.

The proposed invention is aimed at solving the problem of cleaning oil from organochlorine compounds to a level of not more than 0.0003 wt. % without changing the technological scheme and equipment of the oil desalination unit of the primary oil refining unit.

The problem is solved by a method of cleaning oil from organochlorine compounds, including mixing oil with a demulsifier, adding a washing solution containing an inorganic base and a neutralizer to the mixture, followed by separating oil and water under the action of heat and / or an electric field (electric dehydrator), while the neutralizer uses steamed acidic water with its content in the wash solution 98.14–99.5 wt. %.

The technical result achieved by the proposed method is due to its new properties discovered during research.

The stripped acidic water used in the proposed method as a neutralizer has a complex effect both on the degree of oil refining and on the technological process as a whole. On the one hand, the stripped acidic water does not introduce additional contaminants into the refined oil and improves the quality of the product. On the other hand, the used stripped acidic water is taken from separate technological units of the refinery, i.e. reuse of raw materials is used, which makes the proposed method economical and environmentally friendly.

The claimed method is carried out as follows.

The crude oil is mixed with the required amounts of demulsifier, stripped acidic water and an inorganic base. The mixture is heated to a temperature of 135-150 ° C, maintained at this temperature and operating pressure in an electric dehydrator for 15 minutes, and drainage water is separated from oil.

Tests were carried out to remove organochlorine compounds (OCs) from oil at different ratios of inorganic bases - alkali, oil and stripped acidic water.

The following examples illustrate the present invention.

Example 1.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (NaOH - dry) - 0.0028 wt. % calculated on oil;

- the content of stripped acidic water in the washing solution is 99.95 wt. %;

- dosage of Dissolvan 3431 demulsifier - 5 mg / kg.

The resulting mixture is heated to 135 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - from 1.3 to 1.5 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.0003% of the mass.

Example 2.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (NaOH - dry) - 0.0285 wt. % calculated on oil;

- the content of the stripped acidic water in the washing solution is 99.5 wt. %;

- dosage of Dissolvan 3431 demulsifier - 5 mg / kg.

The resulting mixture is heated to 135 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - from 1.3 to 1.5 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.0003 wt. %.

Example 3.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (NaOH - dry) - 0.0357 wt. % calculated on oil;

- the content of stripped acidic water in the wash solution is 99.38 wt. %;

- dosage of FLEK-D-003 demulsifier - 5 mg / kg.

The resulting mixture is heated to 140 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - from 1.3 to 1.5 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.0003 wt. %.

Example 4.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (NaOH - dry) - 0.053 wt. % calculated on oil;

- the content of stripped acidic water in the washing solution is 99.08 wt. %;

- dosage of Dissolvan 3431 demulsifier - 5 mg / kg.

The resulting mixture is heated to 135 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - from 1.3 to 1.5 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.00023 wt. %.

Example 5.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (NaOH - dry) - 0.071 wt. % calculated on oil;

- the content of the stripped acidic water in the washing solution is 98.76 wt. %;

- dosage of Kemelix demulsifier - 5 mg / kg.

The resulting mixture is heated to 145 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - from 1.3 to 1.5 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.00015 wt. %.

Example 6.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (NaOH - dry) - 0.107 wt. % calculated on oil;

- the content of stripped acidic water in the washing solution is 98.14 wt. %;

- dosage of Dissolvan 3431 demulsifier - 5 mg / kg.

The resulting mixture is heated to 135 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - from 1.3 to 1.5 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.0001 wt. %.

Example 7.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (NaOH - dry) - 0.071 wt. % calculated on oil;

- the content of stripped acidic water in the wash solution is 99.76 wt. %;

- dosage of Kemelix demulsifier - 5 mg / kg.

The resulting mixture is heated to 150 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - 1.6 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.0003 wt. %.

Example 8.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (KOH - dry) - 0.071 wt. % calculated on oil;

- the content of stripped acidic water in the washing solution is 98.14 wt. %;

- dosage of Randem-2208 demulsifier - 5 mg / kg.

The resulting mixture is heated to 150 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - 1.6 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.0003 wt. %.

Example 9.

For cleaning, take the original oil with the following characteristics:

Oil, demulsifier, stripped acidic water and alkali are mixed at the following ratio of components:

- the amount of washing solution - 5 wt. % calculated on oil;

- the amount of alkali (KOH - dry) - 0.107 wt. % calculated on oil;

- the content of stripped water in the washing solution is 99.76 wt. %;

- dosage of Randem-2208 demulsifier - 5 mg / kg.

The resulting mixture is heated to 150 ° C and kept for 15 minutes at this temperature in an electric dehydrator at a pressure of 1.0 MPa (at the end of the experiment - 1.6 MPa). Then the drainage water is separated and the oil obtained is analyzed.

The content of organochlorine compounds in the NK-204 ° C fraction of refined oil is 0.0003 wt. %.

The presented examples illustrate that under the influence of temperature and hydrolysis, the content of organochlorine compounds such as carbon tetrachloride and chloroform decreases to 0.0001-0.0003 wt. % s when using a mixture of stripped acidic water and an inorganic base as a washing solution.

The examples are intended to be illustrative and not to limit the scope of the invention, which is defined by the scope of the appended claims.

The proposed method is effective and allows you to remove organochlorine compounds from crude oil to a level of 0.0001-0.0003 wt. % depending on the amount of supplied inorganic base and the content of organochlorine compounds in the original oil.

Claims (1)

A method for cleaning oil from organochlorine compounds, including mixing oil with a demulsifier, adding a washing solution containing an alkali and a neutralizer to the mixture, followed by separating oil and water under the influence of a temperature of 135-150 ° C and an electric field in an electric dehydrator, characterized in that the quality the neutralizer uses steamed acidic water from the technological units of the oil refinery with its content in the washing solution 98.14–99.5 wt.%.