RU2772332C1 - Method for processing watered oil-containing waste - Google Patents

Abstract

FIELD: waste processing.

SUBSTANCE: invention relates to a method for processing watered oil-containing waste containing petroleum products, water, solid phase, including the supply of organic solvent, extraction of petroleum products with solvent, separation of solvent and extracted petroleum products from the solid phase, after the solvent is supplied, the suspension is dehydrated.

EFFECT: development of an effective method for processing watered oil-containing waste to obtain high-quality commercial products suitable for further use or increasing the hazard class of waste, reducing the cost of processing oil-containing waste, eliminating the use of high temperatures at which the destruction of the initial components of waste occurs.

10 cl, 1 dwg, 2 tbl

Description

The invention is intended for processing, regeneration, disposal of oily waste from oil refineries, metallurgy, chemical industry, including products such as soil after emergency spills of oil and oil products, oil sludge, oily scale, used motor oil, etc.

A known method for separating by-products and wastes of the metallurgical industry containing water, oil and scale, including settling without forced heating, decanting oil and water, spraying, vacuum distillation of oil, where before spraying and vacuum distillation of oil, the thickened pulp is subjected to evaporation and heating of the dehydrated mixture to temperature not higher than 160°C, followed by spraying in a vortex flow of water vapor superheated to a temperature not exceeding 400°C and vacuum direct distillation of oil, combined with the sedimentation of solid particles under the action of centrifugal forces and gravity, followed by filtration, after separation of the mixture into the components carry out the condensation of oil vapor and then water (Patent for invention No. 2720193 dated 04/27/2020, Bull. No. 12, Patent holder PAO Severstal, authors Khramov A.V., Sinitsyn N.N., Telin N.V.).

The disadvantage of this method is the dehydration of the thickened pulp in apparatuses with conductive heat supply, which causes uneven heating and low drying intensity. In addition, the extracted oil product in the form of oil has to be distilled in the presence of water vapor and the process temperature up to 400°C, and the solid phase has to be captured from the gas stream.

A known method (prototype) for extracting petroleum products from sludge and contaminated soil, including extraction with an organic solvent and sediment in the extractor, and as an organic solvent an extractant containing aromatic hydrocarbons is used and the extraction is carried out in two countercurrent stages at atmospheric pressure and a mass ratio of extractant raw materials from 1 1 to 2 1, by introducing water into the extractor at the settling stage in an amount that ensures its content in the remainder of 55-60 wt. with subsequent sedimentation of the extractant from water and mechanical impurities introduced into the extractor before the second stage of extraction (Patent for invention No. 2092518 dated 10/10/1997, Patent owners and authors Apostolov S.A. hydrocarbons, a large amount of water to displace the solvent from the solid phase and a high residual content in the solid residue of petroleum products.

The objective of the present invention is to develop an effective method for processing flooded oily waste to obtain high-quality commercial products suitable for further use or increasing the hazard class of the waste, reducing the cost of processing oily waste, eliminating the use of high temperatures at which the destruction of the original components of the waste occurs.

The problem is solved by the fact that during the processing of flooded oil-containing wastes containing oil products, water, solid phase, including the supply of an organic solvent, extraction of oil products with a solvent, separation of the solvent and extracted oil products from the solid phase after the supply of the solvent, the suspension is dehydrated, and the water content is adjusted to a value less than 0.5% (mass), dehydration is carried out by evaporation and with the supply of an inert gas, the solvent is supplied in a volume not less than the volume of water contained in the initial suspension, organic oil refining products are used as a solvent, with a boiling point higher than the boiling point of water, for example, kerosene , diesel fuel, gas oil or others, the dehydration of the suspension is carried out in a sealed water collection system, after the separation of the solvent and extracted petroleum products from the solid phase, the solvent is regenerated by distillation, after the separation of the solvent and extracted oil products from the solid phase, the final separation of the solid phase from the solvent residues is carried out by drying in a sealed organic solvent collection system, and the extraction process is carried out with temperature and pressure fluctuations.

Watered oily solid waste is a single, almost homogeneous viscous mass. Microvolumes of water and oil products in the presence of solid particles mutually block the penetration of an organic solvent or water deep into the mass. Such suspensions do not delaminate, do not spread and present a big technical problem for processing.

When watered viscous oil products are heated above the boiling point of water, it boils explosively with a sharp increase in the volume of the entire product. The reason is poor heat transfer in a viscous medium, hydration of polar compounds of petroleum products and local overheating of the petroleum product.

After removing water to a value of less than 0.5% (mass), there are no obstacles to the penetration of the solvent into the mass and the extraction of extractable oil products. Dehydrated oil-containing waste in a mixture with a solvent breaks down into separate particles, easily settles, is extracted with a solvent and can be recycled.

Removal of water by evaporation provides the most complete removal of it from complex suspensions, in contrast to reagent treatment or centrifugation, which further provides the greatest efficiency for extracting oil products from the solid phase.

The presence of a solvent ensures uniform distribution of heat within the original product during dehydration by evaporation, the mobility of the suspension and mixing between the layers during dehydration.

The process diagram is shown in Fig. one.

Equipment: 1 Mixer, 2 Water Dewatering Unit/Extractor, 3 Liquid/Solid Separator, 4 Solvent/Oil Product Separator.

Process streams: I Initial mixture containing water, solid phase and oil products, II Mixture of solvent and initial product, III Water, IV Dehydrated initial mixture with solvent (extract), V Solid phase, VI - mixture of oil product and solvent, VII Oil product, VIII Solvent (primary), IX Solvent (secondary).

The method is implemented as follows (see Fig. 1). The feedstock (stream I) is mixed in the mixer 1 with the primary solvent (stream VIII) and fed as a mixture (stream II) to the dehydration unit 2, where water is extracted (stream III), at the same time, oil products are extracted from the feedstock with a solvent. The dehydrated mixture (IV stream) in the divider 3 is separated into a solid phase (V stream) and a liquid phase (VI stream), consisting of a solvent with extracted oil products. Further, in the divider 4, the solvent (IX stream) is separated from the oil products (VII stream) and the streams are directed to their destination.

When the water content is less than 0.5% (wt.), the negative effect of water on the extractability of petroleum products and the separation of the liquid phase from the solid is significantly reduced.

Suspension dehydration by evaporation is the most affordable and efficient way to remove water.

The supply of an inert gas during the evaporation of water from a suspension in the form of bubbling makes it possible to exclude local overheating of the suspension due to effective mixing, to lower the temperature of the transition of water into a vapor state, and also to intensify the heat and mass transfer process of evaporation and extraction by increasing the share of the convective mechanism of heat transfer and masses within the suspension.

The solvent supply is carried out in a volume not less than the volume of water contained in the initial suspension, allows you to evenly distribute moisture throughout the entire volume of the suspension, provides a uniform heat supply during evaporation and eliminates explosive vaporization. In the process of evaporation, part of the solvent passes together with water into the vapor phase. Own experimental studies show that the ratio of evaporated solvent to evaporated water in the process of dehydration reaches 1:1. Accordingly, when the solvent is supplied in an amount less than this ratio, the suspension will lose its fluidity, mobility and the possibility of dehydration and separation into components in the future.

Organic petroleum products such as kerosene, diesel fuel, gas oil, or others with a boiling point above the boiling point of water, minimize the transition to the vapor state of the solvent during evaporation and save it for subsequent extraction of hydrocarbons from the solid phase.

Dehydration of the suspension in a sealed water collection system eliminates the loss of hydrocarbons removed with water vapor during evaporation and reduces the environmental burden of the waste processing process.

Solvent recovery allows you to return a valuable product back to the process, and distillation is the most effective way to recover it.

The final separation of the solid phase from solvent residues by drying in a sealed organic solvent collection system minimizes solvent loss and eliminates negative environmental impacts.

The implementation of the extraction process with fluctuations in temperature and pressure makes it possible to intensify the extraction process, increase the degree of extraction of extractable substances due to the oscillating process - temperature expansion of the components of the initial mixture and fluctuations of particles relative to each other.

An example of the implementation of the method. Processing of flooded oily scale.

The initial product is oily scale, which is a pasty homogeneous substance consisting of water, oil and a solid phase, which does not delaminate when treated with water or a solvent under normal conditions. The original product was mixed with kerosene and dehydrated by evaporation at a temperature close to 100°C. The volume of kerosene was 205 ml (250 grams), the water content in the initial suspension was 140 ml. (140 grams). In the process of evaporation with water vapor, kerosene vapor is also released, during the condensation of which a two-phase liquid is formed with a clear phase boundary. Upon evaporation, a condensate was obtained in the form of a mixture of kerosene in a volume of 80 ml and water in a volume of 140 ml. The water content in the mixture after dehydration was 0.1% (mass). After dehydration, a mixture was obtained which is well separated into kerosene with extracted oil and a solid phase in the form of scale, which is a mobile suspension with well-separated solid particles. The resulting mixture is well settled and filtered.

Next, the dehydrated suspension was separated by filtration into a filtrate and a solid precipitate. From the filtrate obtained by distillation, an easily volatile component - a solvent, a non-volatile component - an oil, contained initially in the original product, was obtained. The kerosene obtained during evaporation and distillation of the filtrate does not contain foreign substances and is suitable for reuse as a solvent. The oil obtained after distillation of the filtrate can be used to obtain base oils or cutting fluid.

The solid phase obtained by filtering the suspension was kept at a temperature of 180°C in order to remove kerosene residues and dry scale was obtained, which is a free-flowing red powder with metallic inclusions. The change in the mass of the solid phase during exposure was less than 1%.

The material balance of an example process is shown in Table 1.

Additionally, during the dehydration process, the water content in the initial and final product was measured and its effect on the possibility of gravity separation (settling) was assessed. The results of experimental studies are presented in table 2.

Settling was understood as the possibility of complete settling of suspensions in the liquid after 24 hours. If, over time, the mixture of solvent with extractable hydrocarbons acquired a transparent appearance, it was considered that the suspension settled, if any turbidity remained in the liquid phase, despite the fact that a significant part of the solid phase settled, it was considered that the suspension did not settle.

According to the results of experimental work on the dehydration of the mixture, it was concluded that the limiting water content is 0.5% (mass.), Influencing the settling of the suspension.

The advantages of this invention are the simple instrumentation of the process, the environmental and industrial safety of the process, the minimum content of impurities in the final separation products, the relative low cost of the processing process, the simplification of the operating conditions of the equipment, and the possibility of profiting from waste processing by obtaining and selling liquid products.

Claims (10)

1. A method for processing flooded oily wastes containing oil products, water, a solid phase, including the supply of an organic solvent, the extraction of oil products with a solvent, the separation of the solvent and extracted oil products from the solid phase, characterized in that after the solvent is supplied, the suspension is dehydrated. 2. The method according to p. 1, characterized in that the water content in the stage of dehydration is adjusted to a value of less than 0.5% (mass.). 3. The method according to p. 1, characterized in that the suspension is dehydrated by evaporation. 4. The method according to p. 3, characterized in that the evaporation is carried out with the supply of an inert gas. 5. The method according to p. 1, characterized in that the solvent is supplied in a volume not less than the volume of water contained in the initial suspension. 6. The method according to p. 1, characterized in that organic products of oil refining are used as a solvent, with a boiling point higher than the boiling point of water, for example, kerosene, diesel fuel, gas oil or others. 7. The method according to p. 1, characterized in that the dehydration of the suspension is carried out in a sealed water collection system. 8. The method according to p. 1, characterized in that after the separation of the solvent and extracted oil from the solid phase, the solvent is regenerated by distillation. 9. The method according to p. 1, characterized in that after the separation of the solvent and extracted oil products from the solid phase, the final separation of the solid phase from the solvent residues is carried out by drying in a sealed organic solvent collection system. 10. The method according to p. 1, characterized in that the extraction process is carried out with fluctuations in temperature and pressure.

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