RU2356849C2 - Installation for electrolytic purification of oil containing water - Google Patents

Abstract

FIELD: petroleum chemistry.

SUBSTANCE: invention refers to electrolytic purification of refinery water containing emulsified and colloidal dispersed contaminations and can be implemented for purification of refinery water at oil, chemical and gas industries. The installation of electrical purification of refinery water from suspended substances and oil products consists of a case, of branches for inlet and outlet of water, of a source of direct current and of electrodes arranged so, that two or more porous cathodes successively assembled downstream create cathode chambers between them, two or more porous anodes create anode chambers between them, also the last cathode and the first anode form between-electrode chamber; all chambers are equipped with branches of floating sludge discharge; in addition, the first cathode has potential more negative, than the second cathode, the second one has potential more negative, than the third one an so on; while the first anode has potential more positive, than the second anode, the second anode has potential more positive, than the third one and so on; anodes are fabricated out of material insoluble at anode polarisation.

EFFECT: increased efficiency of refinery water purification.

3 cl, 1 dwg, 1 tbl

Description

The device relates to the field of electrolytic treatment of wastewater containing emulsified and colloid-dispersed contaminants, and can be used for wastewater treatment at enterprises of the oil, chemical and gas industry.

A device is known (RF patent No. 2132821, IPC C02F 1/46. Device for electrolytic water treatment. / Popov A.Yu. // Publish. 07/10/1999), which is intended for electrolytic treatment of water, for example, anode to obtain disinfectant solutions or cathodic to soften water. In a vertical diaphragm flow-through electrolyzer containing a working and auxiliary chambers, the last of which is equipped with a circulation circuit, the inner electrode is made hollow. In this case, the cavity of the inner electrode is connected by the inlet and outlet openings to the auxiliary chamber, thereby forming a circulation loop filled with auxiliary solution and placed inside the hollow electrode.

The disadvantage of this device is the low efficiency of wastewater treatment.

The closest technical solution (prototype) is the invention (RF patent No. 2157344, IPC C02F 1/465. Method and device for electrochemical wastewater treatment / Beigeldrud G.M., Gablenko V.G., Makarenko S.N. // Publ. 10.10.2000), related to the electrochemical treatment of wastewater containing emulsified and colloidal-dispersed contaminants. The process is conducted in modes giving the maximum possible saturation of the liquid with electrolysis gas bubbles with a diameter of 0.3-0.9 microns. The current density on hydrophobic insoluble electrodes located in the lower part of the Central cylinder, support within 200-400 A / m ² . The Reynolds number in the flow of the liquid to be cleaned, going from the bottom up, is maintained within 2000-2700, after which the liquid flow is compressed over the area of the bore, providing a flow within the number Re 3500-4500, followed by a sharp expansion. As a result of such a combination of conditions and modes, particles of contaminants are enlarged, carried away by foam and separated on relatively coarse filters. After expansion, the flow is passed through a second electrode unit, the horizontally located electrodes of which are made of porous non-woven filter material, while on the porous horizontal electrodes the current density is maintained within 100-200 A / m ² and the flow rate of the liquid is maintained from the condition of the value of the number Re in the limits of 120-200. The proposed method is implemented in an electroflotator containing a cylindrical housing with a lid and a coaxially located lower housing. In the lower part of the lower case are vertical anodes and cathodes made insoluble from the expanded carbon material. In the upper part of the lower case, narrowing was performed with a reduction in the bore section by 20-40 times, after which there is an expansion chamber. The inlet of the purified water is located below the indicated electrode unit, and the outlet of the purified water is located in the lower part of the upper case. At the bottom of the annular cavity formed by the upper and lower bodies, there are perforated horizontal anodes and cathodes made of filtering electrically conductive material such as carbonetalkalon.

The disadvantage of this invention is the low degree of wastewater treatment. The narrowing in the upper part of the lower case leads to an increase in the surface of the apparatus, and consequently, to an increase in metal consumption. The process of narrowing the cross section of the apparatus with subsequent expansion, leading to the enlargement of the extracted particles, is carried out only once. Do not use electric fields that lead to inhibition of pollution particles.

The objective of the invention is to increase the efficiency of wastewater treatment and reducing the metal consumption of the device.

The problem is solved in that in the device for electrolytic wastewater treatment from suspended solids and oil products, including a housing, water supply and drain pipes, a direct current source and electrodes, according to the invention, the electrodes are arranged so that two or more porous electrodes are arranged in series cathodes form cathode chambers, two or more porous anodes form anode chambers, the last cathode and first anode form an interelectrode chamber, all chambers They are removed by flotation sludge outlet pipes, the first cathode having a potential more negative than the second cathode, and the second more negative than the third one, etc., the first anode has a more positive potential than the second anode, and the second anode is more positive, than the third, etc., the anodes are made of a material insoluble in anodic polarization. In addition, according to the invention, the thickness of the electrodes is d = 0.04 m, the width of the cathode and anode chambers is c = d, the width of the interelectrode chamber is L = (2 ... 3) d. The electrodes are made of highly porous graphite and have an inclination angle relative to the vertical equal to 0 ... 45 °.

Wastewater containing dispersed suspended solids and petroleum products typically contains natural or synthetic surfactants that stabilize the dispersed system. Solid and liquid dispersed particles having a size of 10 μm or more are removed from water by known methods without any particular problems, for example, sedimentation. To extract small particles, reagent water treatment with coagulants and flocculants is used in practice. Reagent water treatment leads to additional material costs for the purchase of reagents, for the manufacture of a reagent farm. The precipitate formed during the reagent treatment contains metal hydroxides that limit the possibility of disposal of the precipitate and determine their hazard class.

The drawing shows a device for electrolytic wastewater treatment.

The device consists of a cylindrical housing 1 and conical covers 2. In the housing of the device at an angle of 0-45 ° relative to the vertical, porous or perforated cathodes 3 are located, the number of which is two or more, and anodes 4, the number of which is two or more. The cathodes and anodes are connected to a direct current source and have different potential values. Anodes are made of a material insoluble in anodic polarization (graphite, cobalt oxide titanium anode, ruthenium oxide titanium anode, etc.), cathodes are made from skeletal nickel or copper, porous graphite. The electrodes form the cathode chambers 5, the interelectrode chamber 6, the anode chambers 7. All chambers have nozzles 8 for discharging contaminants.

The device operates as follows. Water is passed in homogeneous electric fields having a different direction of the electric field vector E. For this purpose, the water flows sequentially in one or more cathode cells 5 against the vector E _k , then in the interelectrode chamber 6 against the vector E ₀ , after which it passes in one or more anodic chamber 7 in the direction of the vector E _a.

Recoverable particles have a certain value of the electrokinetic charge and potential, therefore, in an electric field, electrostatic forces act on them. During the passage of positively charged particles in the porous cathode medium, the charge of particles is neutralized, which leads to homocoagulation of these particles with the formation of aggregates due to molecular forces. The enlargement of particles and a decrease in the free surface energy of the particle aggregate is determined by the second law of thermodynamics.

Particles that have an uncompensated charge are affected by electrophoretic forces from the side of the electric field. The effect of electrophoretic inhibition of positively charged particles is observed both in the cathode chambers and in the interelectrode chamber.

At the cathodes during their cathodic polarization, hydrogen gas is released, which forms small bubbles rising to the upper part of the apparatus. Bubbles float on the surface dispersed solid and liquid particles and the resulting aggregates of particles. The flotum sludge is discharged through the corresponding nozzles 8. When the electrodes are tilted, an incident water flow with a speed V flushes gas bubbles from the cathode surface, directing them upward.

Next, the water enters the anode chambers 7, where it passes in the direction of the vector E _A. When passing through the porous anodes 4, partially negatively charged particles, mainly oil droplets, are neutralized. Their coalescence occurs with the formation of larger droplets. In the anode chambers, electrophoretic inhibition of negatively charged particles is observed. At the anodes, gaseous oxygen bubbles are released, which float small and large drops of oil on the surface of the apparatus and are discharged from the device through the corresponding nozzles 8.

The recommended electric field strength E _k = E _A = 100-150 V / m, the electric field strength in the interelectrode chamber should be slightly higher and amounts to E ₀ = 120-200 V / m, respectively. The optimal flow rate of wastewater is 10 m / h.

A device for electrolytic wastewater treatment is connected to the pressure outlet of the mechanical treatment facilities using a flange connection. The working pressure of the apparatus is 0.2-0.5 MPa. The electrodes are located at an angle of 0-45 ° relative to the vertical. The thickness of the electrodes d = 0.04 m, the width of the cathode and anode chambers c = d, the interelectrode chamber L = (2 ... 3) d, the energy consumption is 0.01 kWh / m ³ .

Example: Purification was carried out by industrial water of an oil company.

The test results of the device are shown in the table.

Voltage The concentration of suspended solids, mg / l The concentration of petroleum products, mg / l Cathodes Anodes Ref. Ost. Effect, % Ref. Ost. Effect, % 1st 2nd 3rd 1st 2nd 3rd -one -one absent +1 +1 absent 34 22 35 21 12 43 -5 -5 absent +5 +5 absent 34 8 76 21 7 67 -10 -10 absent +10 +10 absent 34 6 82 21 four 81 -twenty -twenty absent +20 +20 absent 34 5 85 21 3 86 -10 -5 absent +10 +5 absent 34 3 91 21 2 90 -10 -10 -10 +10 +10 +10 34 5 85 21 3 86 -10 -6 -2 +10 +6 +2 34 one 97 21 one 95

From the above results it follows that with two cathodes and two anodes the best effect was obtained with unequal potentials of the cathodes and anodes. The use of a third cathode and a third anode improved the cleaning effect. The best effect is achieved in the case of inequality of the potentials of the cathodes and inequality of the potentials of the anodes. The optimal potential value of the cathodes is -10, -6, -2 V, anodes +10, +6, +2 V.

Thus, an increase in the effect of water purification is achieved due to the multiple narrowing and expansion of the water flow, as well as due to the movement of water in the electric field along and against the electric field vector, and the repeated purification of water by separate flotation by hydrogen and oxygen bubbles.

Claims (3)

1. Device for electrolytic wastewater treatment from suspended solids and oil products, including a housing, water supply and drain pipes, a direct current source, electrodes, characterized in that the electrodes are arranged so that two or more porous cathodes are arranged in series along the water flow between cathode chambers, two or more porous anodes form anode chambers between each other, the last cathode and the first anode form an interelectrode chamber, all chambers are equipped with nozzles for the removal of sludge, moreover, the first cathode has a potential more negative than the second cathode, and the second is more negative than the third, and so on, the first anode has a more positive potential than the second anode, and the second anode is more positive than the third, and so on, the anodes are made of a material insoluble in anodic polarization. 2. The device according to claim 1, characterized in that the thickness of the electrodes is d = 0.04 m, the width of the cathode and anode chambers c = d, the width of the interelectrode chamber L = (2-3) d. 3. The device according to claim 1, characterized in that the electrodes have an angle of inclination relative to the vertical equal to 0-45 °.