RU2194738C1 - Method of processing trapped oil - Google Patents

Abstract

FIELD: waste water treatment. SUBSTANCE: invention relates to cleaning and processing oil-containing waste waters and oil sludges, in particular reusing petroleum products recovered from waste waters, liquid and viscous oil sludges. Trapped oil with up to 10% water content is heated in furnace to 325- 385 C and then separated in rectification column into gasoline, diesel, and residual fractions under pressure 0.15 to 0.5 MPa depending on water content, said trapped oil being recovered from waste water or oil sludge and pretreated in disperser to form homogenous water-oil emulsion with drop size no larger than 30 mcm. EFFECT: enabled processing of trapped oil with water content up to 10% without preliminary settling, increased commercial product output from 15 to 100 rel %, reduced pollution, and improved environmental condition. 2 cl, 1 tbl, 5 ex

Description

 The invention relates to the field of purification and processing of oily wastewater and oil sludge, in particular for the disposal of oil products isolated from wastewater, liquid and viscous oil sludge.

 Known methods for wastewater treatment at oil refineries (refineries) include the initial stages of purification and sedimentation in sand traps and oil traps, in which the main part of oil products - trap oil - is released as a result of gravitational sedimentation from sewage treatment plants [1. Joachimis E.G. et al. Non-waste technology for wastewater treatment at refineries. - M .: TsNIITEneftekhim, 1977, p. 8-9]. Then, wet trap oil enters the cutting tanks, in which additional sedimentation from the water takes place, from where the upper layer of dehydrated oil, containing not more than 1.5-2.0% of water, goes to the processing according to various known schemes, including in a mixture with source oil [2. J. G. Sorkin. Waste-free production in the oil refining industry. - M.: Chemistry, 1983, p. 175-177].

 A known method of processing the hydrocarbon portion of liquid oil sludge on a special unit for processing trap oil [3. NR Sayfullin and others. Oil refining and petrochemicals. - M.: TSNIITEneftekhim, 3, 1998, p. 46-49]. However, in order to prepare for processing, the hydrocarbon part of the liquid sludge, which is in the form of a stable emulsion, undergoes a thorough and lengthy multi-stage dehydration procedure until there is practically no water in the upper oil layer. At the same time, secondary gas oil is added to break the emulsion, and after separation of the upper layer, the remaining persistent non-destructible emulsion with oil is again dehydrated in the presence of a demulsifier mixed with the emulsion from treatment facilities. Then, the flooded (up to 20 wt.%) Hydrocarbon portion is mixed with the components of the boiler fuel and again sedimented from the water to its trace amounts in the fuel.

 The main disadvantage of this method is its duration, multi-stage, the use of additional reagents (demulsifiers) and petroleum products (secondary gas oils, boiler fuels), which can be used more skillfully.

 Closest to the technical nature of the proposed method is the technology of processing trap oil in atmospheric distillation units, which is practiced at some refineries [4. N.V. Gavrilov. Oil refining and petrochemicals. - M .: TsNIITEneftekhim, 1988, p. 9].

 The disadvantage of this method is that the traditionally collected oil trap product is first subjected to sedimentation from water and mechanical impurities in the cutting tanks of treatment facilities, and then in a mixture with the original oil enters the ELOU unit, where it is released to a residual water content of no more than 1- 1.5 wt.%. Next, the oil enters the atmospheric distillation unit, where, according to the well-known scheme, separation is carried out into main fractions (gasoline, diesel, residual).

 Another disadvantage of the known technology is that trapped oil is processed separately from other oil products extracted from oil sludge at the treatment plant, since these oil products contain a significant amount of water (up to 20 wt.%). In this regard, the efficiency of the conversion of the hydrocarbon phase into a calculated product is not high enough.

 The technical task of the proposed method is to increase the efficiency of the disposal of petroleum products extracted from wastewater, liquid and / or viscous oil sludge.

The problem is solved in that in the method of processing trap oil by heating in an oven to 320-385 ^o With subsequent separation in a distillation column into gasoline, diesel and residual fraction using trap oil with a water content of up to 10 wt.%, Extracted from wastewater , liquid and / or viscous oil sludge, processed before being fed into the furnace in a dispersant to form a homogeneous oil-water emulsion with a droplet size of not more than 30 microns, while the separation in the distillation column into gasoline, diesel and residual th fraction carries pressurized 0.15-0.5 MPa depending on the water content in the emulsion.

 Salient features of the invention include the use of trap oil with a water content of up to 10 wt.%, Isolated from waste water, liquid and / or viscous oil sludge; processing before feeding into the furnace in the dispersant to form a homogeneous oil-water emulsion with a droplet size of not more than 30 microns; separation in a distillation column into gasoline, diesel and residual fractions under a pressure of 0.15-0.5 MPa, depending on the water content in the emulsion.

 The combination of essential distinguishing features allows to increase the efficiency of utilization of all oil products separated at treatment facilities, including viscous sludge that is removed from storage ponds, thereby reducing the accumulation of environmentally harmful hydrocarbon compounds in the territories around the refinery. At the same time, sludge oil products are converted according to the proposed method into valuable calculable products-components of various fuels.

 As a dispersant in the proposed method, a hydrodynamic activator of a special design (GDA) or a static dispersant (SD) of a special design, or a centrifugal circulating pump (TsN), which works according to the reservoir-pump-reservoir scheme for a time sufficient to create an emulsion with a size drops not more than 30 microns.

 The following are specific examples illustrating the implementation of the method.

 Example 1. Trap oil extracted from wastewater after settling in cutting tanks to a water content of 5.3 wt.%, Is fed to the HDA and treated for 8 s until a homogeneous emulsion with a droplet size of 12-18 microns is formed.

The resulting emulsion is heated in an oven to a temperature of 385 ^{° C.} and sent to a distillation column for separation, in which a pressure of 0.5 MPa is maintained. Get the products, wt.%: Gasoline fraction is a component of marketable gasoline 3.6; diesel fraction - a component of commercial diesel fuel 7.0; the residual fraction is a component of fuel oil 85.4; gas + loss 4.0.

 Examples 2, 3, 4 are carried out analogously to example 1, but the conditions (temperature, pressure), the water content in the trap oil entering the separation are changed, and various dispersants are used. In Example 2, trap oil consists of a hydrocarbon phase (top layer) separated from wastewater and viscous sludge that is pumped from sludge collectors to a settling tank. In example 3, trap oil consists of hydrocarbons extracted from wastewater, liquid (2 parts by weight) and viscous (1 parts by weight) sludge, but any ratios can be used depending on the balance of oil products from those and other sludge. The content of mechanical impurities in hydrocarbons varies from 0.8 to 2.5 wt.%, Water from 2 to 10 wt.% Depending on the duration of sedimentation of sludge in the tank or the method of their destruction.

 Example 5 is carried out according to the known method with trap oil, which settled in tanks up to 0.83 wt.% Water. All information on examples is given in the table.

 From the data presented in the table it can be seen that the new method is effective, since it allows the processing of trap oil containing up to 10% water, and does not require long-term sedimentation to a minimum content or trace amounts. Oil products separated from liquid and viscous sludge are also qualitatively disposed of, and, thus, production of marketable products increases from 15 to 100 rel.%. In addition, the processing of viscous sludge from sludge collectors reduces pollution and improves the environmental situation in the territory of treatment facilities.

Claims (2)

1. The method of processing trap oil by heating in an oven to a temperature of 320-385 ^o With subsequent separation in a distillation column into gasoline, diesel and residual fractions, characterized in that they use trap oil with a water content of up to 10 wt. % extracted from wastewater, liquid and / or viscous oil sludge, processed before being fed to the furnace in a dispersant to form a homogeneous oil-water emulsion with a droplet size of not more than 30 microns.  2. The method according to p. 1, characterized in that the separation in the distillation column into gasoline, diesel and residual fractions is carried out under a pressure of 0.15-0.5 MPa, depending on the water content in the emulsion.

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