RU2065409C1 - Method for prevention of formation of deposits and corrosion - Google Patents

Abstract

FIELD: prevention of formation of deposits and corrosion in closed water supply systems and water supply systems without drainage. SUBSTANCE: method for prevention of formation of deposits and corrosion includes dissolving of phosphon-containing complexonates in water and introduction of obtained solutions into treated water. In this event, solutions of complexonates and complexonex are prepared in magnetic field for 1-10 min. EFFECT: higher efficiency. 1 cl, 5 tbl

Description

 The invention relates to methods for preventing deposits of mineral salts and corrosion of equipment in aqueous solutions and can be used in the field of water treatment to create closed and drainless water supply systems.

A known method of preventing deposits by treating water in a magnetic field with optimal field strength and flow rate [1]
However, this method has several disadvantages: magnetic treatment is effective for a certain salt composition of water of a certain calcium carbonate hardness. In the case of sulfate hardness, this method does not give positive results. The presence of a high concentration of carbon dioxide in water, the presence of other dissolved and undissolved impurities adversely affects the effect of magnetic treatment. All these factors have a significant impact on the effectiveness of magnetic processing, leading to frequent reconfiguration of magnetic devices due to changes in water quality. In addition, magnetic treatment has practically no effect on the change in the corrosion properties of water.

Closest to the proposed is a method of preventing deposits and corrosion by introducing into the treated water aqueous solutions of complexones containing aminoalkylphosphonic groups or their mononuclear zinc complexonates [2]
The known method is not effective enough in closed and drainless water supply systems for the following reasons:
carbonate hardness, at which the use of complexones is possible, is limited to 7 mEq / l;
corrosion inhibition by phosphorus-containing complexones is insufficient and does not exceed 30%. When using zinc mononuclear complexonates, the efficiency of corrosion inhibition increases to 90-95%, however, the reagent consumption is 30-50 mg / l;
when using phosphorus-containing complexones in a drainless water supply system, they are not effective enough due to destruction by bioorganisms. To maintain their effectiveness, they must be used in conjunction with a copper ammonium complex of hydroxyethylene diphosphonic acid, which increases the cost of water treatment.

 diluted (1-5%) solutions of phosphorus-containing complexones must be prepared with industrial water. The use of recycled water with high hardness (10 mEq / l) is impossible, because when preparing solutions on such water, poorly soluble calcium salts are formed which precipitate, and the efficiency of water treatment decreases.

 The technical task of the invention is to increase the efficiency of water treatment while reducing the consumption of reagents in closed and drainless water supply systems.

 The problem is solved in that aqueous solutions of organophosphonates and their mononuclear complexonates are dissolved and prepared in a magnetic field for 1-10 minutes.

 In the preparation of inhibitors in a magnetic field, conditions are created for the active association of ions, fluctuations in their concentrations, and disruption of ion hydration shells. As a result of these processes, the effectiveness of the reagents when they are used in closed and drainless water supply systems increases.

нитрилтриметиленфосфоновая кислота НТФ (ТУ 6-09-20-13-78)

2-гидрокси-1,3-пропилендиаминтетраметиленфосфоновая кислота ДПФ (ТУ 6-09-4915-80)

ИОМС ингибитор отложений минеральных солей, представляющий собой композицию, содержащую нитрилтриметиленфосфоновую, иминобисметилфосфоновую, полиэтиленполиаминополиметиленфосфоновую кислоты, выпускаемый согласно ТУ 6-05-21-1153-81.The following compounds are used as organophosphonates:
hydroxyethylidene diphosphonic acid OEDP (TU 6-09-20-13-78)

nitrile trimethylene phosphonic acid NTF (TU 6-09-20-13-78)

2-hydroxy-1,3-propylene diamine tetramethylene phosphonic acid DFT (TU 6-09-4915-80)

IOMS is an inhibitor of mineral salt deposits, which is a composition containing nitrile trimethylene phosphonic, iminobismethylphosphonic, polyethylene polyaminopolymethylene phosphonic acid, manufactured according to TU 6-05-21-1153-81.

 Comparative characteristics of the effectiveness of the proposed and known methods are shown in table 1.

 Examples of the method.

 Example 1. An aqueous 5% solution of oxyethylene diphosphonic acid (HEDP) is prepared by dissolving in water in a magnetic field at a magnetic field strength of 1700 Oe and a fluid velocity of 0.6 m / s. To prepare the solution, the Kazmekhanobr magnetic apparatus was used. The processing time of the solution is 0.5-15 minutes. The resulting solutions were tested as scale inhibitors during crystallization of calcium carbonate.

A calcium bicarbonate solution is prepared by mixing equivalent amounts of sodium bicarbonate and calcium chloride. The concentration of the resulting solution is 10 mEq / L. A supersaturated calcium sulfate solution is prepared by mixing equivalent amounts of sodium sulfate and calcium chloride. The concentration of calcium sulfate is 7.5 g / l. The experiments were carried out with stirring (Re c = 12500) and a temperature of 60 ± 0.1 ^o C. The resulting reagent solutions were used in the form of 0.1% solutions. The reagent concentration in the test solution is 5 mg / L. Efficiency was evaluated by the duration of the induction period, determined by the results of chemical analysis by a graphical method. The data are shown in table 2.

 From the data presented in table 2 it is seen that in those cases when the preparation of the reagent was carried out in a magnetic field, the induction period of crystallization increased by 20-100%. The optimal processing conditions are from 1 to 10 minutes. Reducing or increasing the specified processing time does not allow to achieve the claimed technical result.

 Example 2. Obtaining a mononuclear complexonate in a magnetic field with a field strength of 1700 Oe and a fluid velocity of 0.6 m / s. The zinc sulfate solution (5%) was treated with an alkali solution (40%) until a pH of 9 was reached. A 25% solution of nitrile trimethylene phosphonic acid (NTP) or an inhibitor of mineral salts (IOMS) was gradually introduced into the resulting suspension, which was zinc hydroxide. obtaining a homogeneous solution. Processing in a magnetic field was carried out for 0.5-15 minutes. The prepared solutions were tested as water corrosion inhibitors of the following chemical composition: pH 9.5, alkalinity 0.7 mEq / l, hardness 2.5 mEq / l, salinity 230 mg / l, iron (total) 8, 0 mg / l, sulfates 45 mg / l, chlorides 80 mg / l.

 The corrosion rate of structural steel was determined on an Oka corrosion meter according to a known method. The data are presented in table 3.

 From the data presented in Table 3, it can be seen that in the case of preparation of zinc mononuclear complexonate in a magnetic field, it is possible not only to increase the efficiency of corrosion inhibition, but also to reduce the concentration of complexonate by 6 10 times. This reduces the reagent consumption, especially if used in open systems. The optimal processing time is 1-10 minutes.

Example 3. Aqueous solutions of complexonates were prepared in a magnetic field with a strength of 1700 Oe at a flow velocity of 0.6 m / s. Processing time in a magnetic field 5 minutes The solutions are thermostated at 40 ^o C for 60 days. Once every 20 days, the effect of the prepared solutions on the crystallization of calcium sulfate was determined. A supersaturated calcium sulfate solution of an initial concentration of 8 g / l is prepared by mixing equivalent amounts of sodium sulfate and calcium chloride. The effectiveness of the reagents was tested at 80 ^o C and a holding time of 3 hours. The concentration of reagents is 5 mg / L. Under similar conditions, mixtures of NTF with a copper-ammonium complex of hydroxyethylidene diphosphonic acid (MDPC) were tested at an optimal ratio. The data are shown in table 4.

As can be seen from the data presented in Table 4, the treatment of a complexon solution in a magnetic field eliminates the use of MDFK in the composition, the use of which significantly increases the cost of water treatment. Compared with reagents that are not processed in a magnetic field, the effectiveness of the proposed method is more than 60% higher
Example 4. The preparation of aqueous 1-2% solutions of complexones was carried out on water with a total hardness of 15 mEq / l in a magnetic field of 1700 Oe at a flow rate of 0.6 m / s for 10 minutes and without it. Loss of reagents as a result of precipitation, which are polynuclear calcium complexonates, was determined by changing the concentration of complexones in solution according to the standard method and visually.

 The data are presented in table 5.

From the data shown in table 5, it is seen that in the case of the preparation of reagent solutions in a magnetic field, its losses are practically equal to zero. If the preparation of the reagents is carried out not in a magnetic field, the losses are 27-35%
Thus, the technical and economic advantages of the method are to increase the efficiency of water treatment in order to prevent the formation of deposits and corrosion, expand the possibility of using complexones in closed water supply systems, reduce the consumption of reagents when inhibiting corrosion, and prepare solutions in highly mineralized waters. TTT1 TTT2 TTT3 TTT4

Claims (1)

 A method of preventing the formation of deposits and corrosion by introducing solutions of phosphon-containing complexones into the treated water, characterized in that solutions of metal complexones and complexonates are prepared in a magnetic field for 1 to 10 minutes.

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