RU2175644C1 - Electric coagulator - Google Patents

Abstract

FIELD: electric coagulated purification of water from hardness salts and other impurities with use of anodes subjected to electrochemical dissolution. SUBSTANCE: electric coagulator in the form of electrode block has rectangular case with lower bottom, upper flange, plane-parallel unipolar electrodes connected in pairs and separated by insulating spacers from each pair of electrodes of opposite polarity, positive and negative current leads, water inlet and outlet unions. Cylindrical case of electric coagulator has lower spherical bottom and upper spherical cover. Wall and bottom of electrode block are fitted with insulating spacers with grooves in which insulating spacers are installed with formation of isolated chambers. Lower bottom of electrode block is perforated. Perforation in isolated chambers is made to middle of bottom with alternation of solid and perforated sections in bottom of chambers. Unipolar pairs of electrodes in each chamber are connected with use of bolt with spacing plate between electrodes. Second end of plate is connected to feeders. L-shaped current conducting plate has hole to accommodate bolt of electrode and cutout in the form of hemisphere to accommodate rod. Feeders are located on insulating strips, on opposite flanges of electrode block. Flanges of electrode block are attached to flanges of cylindrical unions placed on generating lines and butts of cylindrical apparatus. Electrodes and insulating spacers in each electrode block are oriented vertically. EFFECT: enhanced surface of electrodes, raised unit power of electric coagulator and productivity of electrode blocks. 5 cl, 7 dwg

Description

 The invention relates to the field of equipment for electrocoagulation treatment of water from hardness salts and other impurities using anodes subjected to electrochemical dissolution.

Using electrocoagulators avoids warehouse reactants Al ₂ / SO _4/3 • 18H ₂ O and FeCl ₃ • 6H ₂ O, conventionally used for coagulation of water purification as the weight fraction of the active component of Al ³⁺ and Fe ³⁺ is ~ 16%, and the ballast part of the coagulant is absent during the electrolytic production of Al ³⁺ and Fe ^{3+ /} V.A. Klyachko, I.E. Apeltsin. Water treatment for industrial and urban water supply. M .: GSI, 1962, p. 154 /.

Dosing of the electrocoagulant is carried out by regulating the voltage depending on the flow rate and composition of the water and can be easily automated. However, electrocoagulation is not widely used in industry due to the following disadvantages:
-high power consumption up to 12 kWh / cubic meter due to the difficulty of tearing metal ions from the electrode surface, passivation of electrodes, large interelectrode gaps, underdeveloped surface of flat electrodes / V.Yu. Baklan and others in the journal "Chemistry and Water Technology ", N 4, 1992, p. 318 /;
- strict sanitary standards for the content of residual aluminum in drinking water Al ≤ 0.05 mg / l, which cannot be maintained with the existing design of the electrocoagulator / I. M. Solomentsev, L.A. Velichanskaya, I.G. Gerasimenko. The problem of residual aluminum in purified water. N 6, 1991, p. 516 - "Chemistry and water technology" - journal /;
- staining water in orange when using iron electrodes, which is unacceptable according to the requirements of GOST for drinking water. Constructive attempts have been made to eliminate some of these shortcomings. So, to prevent the formation of deposits on the electrodes, it is recommended to change the polarity of the current / A.K. Zapolsky, A.A. Baran. Coagulants and flocculants in water purification processes. L .: Chemistry, 1967, p. 190 /.

 However, the efficiency of the polarity reversal decreased with each new repetition, residual phenomena accumulated and it became ineffective. Acid flushing, overhaul of the electrode bag and mechanical cleaning were required, which required stopping the process or installing a backup coagulator.

 To reduce interelectrode gaps while eliminating breakdowns between the electrodes, insulating distance washers were installed / V.Yu. Cormorant and others. Electrocoagulation treatment of washing water of complex composition. - "Chemistry and water technology", N 4, 1992, p. 319 /. However, with large electrode sizes, the gap could not be reduced to values less than 10-15 mm due to warping and non-flatness of the sheets.

 It is possible to develop the surface of flat electrodes in order to reduce the working current and energy consumption if the electrodes are shaped, for example corrugated. This made it possible to increase the rigidity of the sheets, reduce the gaps, increase the surface and, accordingly, reduce the working current and increase the electrode life before passivation / A.s. N 597743 from 05.16.75, M.C. C 25 N 11/02 /.

In RF patent N 2116259, adopted as a prototype, in an electrocoagulator comprising a housing with plane-parallel profiled electrodes, remote gaskets of insulating material, positive and negative feeders, to which electrodes and water inlet and outlet connections are connected, remote gaskets between anode and cathode electrodes are made continuous parallel to the entire surface of the electrodes with gaps relative to the electrodes and with open passages for water from the lower and upper ends. The metal dissolves at the anode and migrates to the cathode, causing cathodic polarization and passivation. At the same time, OH ^- hydroxyl ions are formed at the cathode, which, migrating to the anode, are discharged to oxygen, which blocks the dissolving surface. The installation of solid jumpers eliminates the interelectrode migration of OH ^- ions and metal ions, as well as the migration of reaction by-products, which dramatically reduces energy losses. The target product - metal ions are carried away by the flow of water and become a coagulant. OH ions ^are also carried away by the flow of water into the open passages of the ends of the electrodes. Moreover ions OH ^- are not discharged until the oxygen, and are involved in the binding of alkaline hardness precipitate. The combination of aluminum and iron makes it possible to solve a number of problems:
- the complex ion / Al ³⁺ + Fe ³⁺ / in combination with hardness salts is a double collector and is able to bind not only hardness salts, but also salts of heavy metals, organics, etc. / V.I. Maxin. Carbonates of alkali metals. - "Chemistry and water technology", N 5, 1991, p.431 /;
- riveting sheets of Al and Fe avoids the difficulties of combining and alternating electrodes, which inevitably arise when the polarity reversal;
- the concentration of medically harmful residual Al ions decreases, as part of them is replaced by iron, and the other part is neutralized by iron and other impurities in the complex compound;
- eliminates the color of the solution, which inevitably occurred when using single Fe, because its concentration decreases and the active iron binds to a neutral compound.

Despite the large contribution of patent No. 2116259 to the solution of electrocoagulation problems, there are a number of disadvantages in the design:
- the rectangular configuration of the apparatus body, repeating the plane-parallel arrangement of the electrode plates, limits the dimensions of the apparatus, because its flat bottoms and walls do not withstand internal pressure. The increase in wall thickness and the installation of stiffeners allows you to compile a device with a volume of up to one cubic meter and a capacity of up to 20 cubic meters. m / h, although the need for productivity is ten times greater than the named;
- the installation of insulating spacers between the electrodes made it possible to sharply reduce the interelectrode migration of ions. But migration was not completely ruled out. there were mounting gaps between the insulating gaskets, the walls and the bottom of the apparatus, where ions freely migrated between the anode and cathode chambers with all the negative consequences - passivation of the electrodes and stray metal flows;
- corrugated electrode option increases the surface of the electrodes only within 20%;
- the working surface of the electrodes is underestimated by placing current leads inside the electrode volume;
- low unit productivity of single electrode blocks, which does not meet modern requirements for water treatment plants on a city and regional scale.

 The aim of the present invention is to provide an electrocoagulator design that solves these problems.

 In FIG. 1 shows the proposed apparatus in longitudinal section, in FIG. 2 is a section AA of FIG. 1, in FIG. 3 is a section DD of FIG. 1, in FIG. 4 is a section BB of FIG. 2, in FIG. 5-6 are views B and B 'of FIG. 4, in FIG. 7 - an attempt to create a large-scale version of the electrocoagulator / EC /.

 An EC in the form of an electrode block includes a rectangular housing 1 with a lower bottom 2, an upper flange 3, plane-parallel paired unipolar aluminum 5 and iron 6 electrodes separated by continuous insulating spacers 7 from each pair of electrodes of reverse polarity 8 and 9, positive 10 and negative 11 current leads , the fitting of the input 12 and output 13 of water. The lower bottom 2 is perforated, and the flange is placed in the lower connector 15 of the cylindrical body 16 having a lower spherical bottom 17 and an upper spherical cover 18 attached to the upper connector 19 of the cylindrical body 16. The wall 1 and the bottom 2 of the electrode unit are provided with insulating spacers 20,21 , 22 with grooves 23,24,25, in which insulating gaskets 7 are installed, forming insulated chambers 26 and 27. Perforation 28 of bottom 22 is made up to the middle of the bottom with alternating whole and perforated sections of the bottom of the chambers, with half of each amers made whole, and half - perforated. The electrodes of each chamber of a unipolar pair of 5.6 and 8.9 were connected using a bolt 29 with a distance plate 30 between the electrodes, the second end of the plate being connected to the current supply 10 or 11. The distance between the electrodes 5 and 6, 8 and 9 should allow passage water without stagnant zones and is, for example, 5 mm. The plate 30 is made L-shaped with a hole for the bolt 29 of the electrodes and a cutout 31 for the current supply rod 10 or 11, and the cutout 31 covers the rod in the form of a hemisphere, and the current leads 10 and 11 with spacer sleeves 32 are located on the opposite strips 33 and 34 flanges of the electrode block. The insulating gaskets 7 are fixed against movement by the strip 4. The flanges 3 of the electrode blocks 35.36.37 are attached to the flanges 38 of the cylindrical fittings 39,40,41 located next to the cylindrical apparatus 42 with the upper 43 and lower 44 spherical bottoms, and the fitting 45 spherical covers the electrode blocks are connected by a pipe 46 of the water outlet 47, and the electrodes 5,6,8,9 and the insulating spacers 7 of each electrode block are oriented vertically. The current lead 10 has an output to external connections through a wire 48, a pin 49 and a wire 50. Similarly, the current lead 11 has an output to an external connection through a wire 51, a pin 52 and a wire 53. The spacers 32 are compressed with nuts 54. The current leads are protected the flange 55 and the casing 56. To facilitate the separation of electrons, the electrodes are provided with perforations 57. The connection of the electrodes 5 and 6 in the prototype is made with rivets 58. The described devices are equipped with water inlet fittings 12, 59, water outlet fittings 12 and 47, as well as air ducts 14, 60 and 61. Prev nipples 62 and 63 are viewed for sludge discharge.

Electrocoagulator works as follows. A voltage is applied to the current lead 10 and 11. Through the nozzle 12 in the apparatus serves water to be softened or cleaned. Passing through the electrode zone, the water is saturated with complex ions - / Al ³⁺ + Fe ³⁺ / c of the anode and alkalized with OH hydroxyl ^{- the} transported stream of water from the cathode.

In this case, the carbonate passes into the form of HCO $\genfrac{}{}{0ex}{}{\text{-}}{\text{3}}$ which, when in contact with hardness salts, forms CaCO microcrystals $\genfrac{}{}{0ex}{}{\text{2-}}{\text{3}}$ . A complex coagulant enlarges crystals, while sorting heavy metal salts, organics and other impurities. The interelectrode migration of metal ions and OH ions ^is absent due to continuous distance walls. Also parasitic end flows i of bipolar ions through mounting gaps, which were in the prototype, are excluded — FIG. 6. In the proposed design - FIG. 5 insulating gaskets 7 are installed in the grooves 23, forming insulated chambers. The problem of inter-chamber flows of bipolar ions at the lower end of the apparatus when water enters the EC is solved by installing a bottom made of insulating material with grooves and original perforation, which excludes close contact of the water flows entering the neighboring chambers. The above measures made it possible to sharply reduce the energy consumption from 0.2 to 0.05 kWh / cubic meter of water, and also to eliminate the polarization of the electrodes. In each EC chamber, two unipolar electrodes are installed instead of one in the prototype. This made it possible to double the working surface of the electrodes with a slight increase in size: between previously riveted sheets 5 and 6 of FIG. 6 introduced a gap δ _{2 of} FIG. 5, which made the inner surfaces of the electrodes active. Interelectrode pitch t ₁ in the prototype was:
t ₁ = (2δ ₁ + S ₁ + 2S ₂ ) = (2 • 5 + 3 + 2 • 2) = 17 mm.

In the proposed design, the step t ₁ increased only δ ₂ = 5 mm and amounted to:
t ₂ = (2δ ₁ + S ₁ + 2S ₂ ) + δ ₂ = 17 + 5 = 22 mm
The current leads in the prototype penetrated the electrodes, reducing their surface and forcing when replacing the electrodes to complete a complete overhaul of the feeders and the entire package of electrodes. In the proposed solution, it is sufficient to loosen the nuts 54 - FIG. 2 and simply remove the paired unipolar electrode together with the distance plate 30, the cutout of which covered the hemisphere of the current lead 10. This dramatically reduces the complexity and time of replacing the electrodes when they are dissolved. The unit productivity of ECs was increased tenfold and the safety of their work was increased. As noted, a rectangular case with internal pressure limited the performance of the apparatus and made it closely monitor the excess pressure from which the seams cracked and flat walls burst. Now the cavities of the inner electrode blocks are under the same pressure, and the difference between the working and atmospheric pressures is perceived by the cylindrical body 16 - FIG. 1 and spherical bottoms 17.16, working perfectly at any pressure. This made it possible to sharply increase the dimensions of the built-in electrode blocks and thereby increase their productivity. However, such an increase in productivity is limited by the mass of electrodes, which periodically need to be changed manually. The layout of the electrode blocks in a vertical cylindrical apparatus greatly increases the unit power of the EC. The production area of the new EC will increase slightly, as vertical cylindrical apparatuses are very compact. However, the new EC is not a simple addition of the same type of modules: it is necessary to observe the condition of the vertical orientation of the electrodes and insulating spacers, otherwise the structure will be destroyed.

 According to the invention, design documentation for industrial EC for drinking water treatment plants Q = 1500 cubic meters per day was developed at Gazprom organizations: underground gas storage stations in Peschany Umet and Mokrous in the Saratov Region.

Claims (6)

 1. An electrocoagulator in the form of an electrode block containing a rectangular case with a bottom, side walls, insulating plates, a top flange and a removable cover, plane-parallel unipolar electrodes separated by continuous insulating plates from electrodes of reverse polarity, positive and negative current leads to all electrodes, input lead and output, characterized in that the connection of the electrodes of each unipolar pair is made with remote current-conducting plates between the electrodes, isol uyuschie gaskets mounted in the slots of insulating walls and bottom electrodes, forming insulated chambers.  2. The electrocoagulator according to claim 1, characterized in that the current supply plate is L-shaped with a hole for the electrode bolt and a cutout for the rod of the current supply feeder, the cutout covering the rod in the form of a hemisphere, and the feeders are located on insulating strips on opposite flanges of the electrode block .  3. The electrocoagulator according to claim 1, characterized in that the distance between the electrodes, as well as between the electrodes and the insulating spacers, must allow passage without stagnant zones, for example, 5 mm.  4. Electrocoagulator according to claim 1, characterized in that the flange is placed in the lower connector of the cylindrical body having a lower spherical bottom and an upper spherical cover attached to the upper connector of the cylindrical body.  5. The electrocoagulator according to claim 1 or 4, characterized in that the lower bottom has perforation, and the perforation in the isolated chambers is made up to the middle of the bottom with alternating whole and perforated sections of the bottom of the chambers, half of the bottom of each chamber is made whole and half is perforated.  6. The electrocoagulator according to claim 1 or 4, characterized in that the flanges of the electrode blocks are attached to the flanges of the cylindrical fittings located along the generatrix and at the ends of the cylindrical apparatus, the electrodes and insulating spacers in each electrode block being oriented vertically.

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