RU2208598C1 - Water cleaning and conditioning process - Google Patents

Abstract

FIELD: water treatment. SUBSTANCE: process suitable for production of drinking water consists in treating water with air oxygen in liquid-gas ejector fitted with multinozzle attachment at water supply rate by at least 25% exceeding sound speed in water-air mixture, after which water is filtered and supplemented by mineral acid in ejecting device. Air is introduced into ejector at reduced (0.3-0.7 atm) or atmospheric pressure if water contains much iron and has low carbonate hardness. In case of high carbonate hardness and low iron content, air is supplied under excessive pressure no higher than 0.3 atm. EFFECT: enabled low-cost deferrization, softening, and decarbonization of water resulting in water with high time stability. 5 cl, 1 dwg

Description

 The invention relates to the field of water treatment and water purification and can be used to prepare water for industrial needs and to produce drinking water.

 A number of water treatment methods for heat supply are known, in which water is deaerated using water-jet ejectors in plants (see, for example, [1], [2], [3]).

 A common drawback of these methods is the presence of additional capacities of the gas separator tank and the vacuum deaerator of the dekorbanizer, which increases the overall dimensions of the devices under consideration. In addition, the device [3] used a vapor-liquid jet apparatus and a cyclone, which further worsens the weight and size characteristics and requires a steam source necessary for the operation of the vapor-liquid jet apparatus.

 A known method of water purification, including mixing purified water with an ozone-air mixture, carried out in a multi-barrel ejector at a relative volume concentration of the mixture 0.35-0.65 by accelerating to supersonic speed with subsequent braking to subsonic speed when the mixture passes through a shock wave [4] .

 However, the implementation of the supersonic flow of the mixture, judging by the description [4], is possible only at a mixture pressure less than 0.14 MPa. In addition, the specified range of relative volumetric concentrations of 0.35-0.65 is quite narrow, which makes this method not effective and economical.

 A known method of water purification from iron, including its mixing with air at atmospheric pressure, processing in a contact tank, filtering with constant selection of water for mixing with dispersed air at a certain pressure of the water-air mixture and saturation time and circulation through the contact tank, and the source water is contacted nozzle with a large specific surface with a water-air mixture supplied to the mixing by a circulation pump through an ejector, the volume of which is equal to or 2-3 times the volume of the flow water supplied for purification [5].

 The disadvantage of this method is the presence of nozzles with a large specific surface area and the need for recirculation of the water-air mixture, which increases energy consumption.

 The closest in technical essence and the achieved result is a method of purification and conditioning of water, including the treatment of water with atmospheric oxygen using an ejector, its subsequent passage through the tank and filtering. In this method, first, water is mixed with atmospheric oxygen at atmospheric pressure using an ejection device, then it is processed in a contact tank and filtered [6]. In this method, the ejector plays an auxiliary role for supplying air from the atmosphere to the pipeline, and the main process of degassing the source water and saturating it with air occurs in a mixer, which together with the dispersant is not able to provide submicron sized air bubbles.

 Another disadvantage of this method is its complexity and increased energy consumption, due to the fact that when water is treated in a contact tank, part of the water is constantly taken, mixed with dispersed air at a certain pressure of the water-air mixture and saturation time, and then returned to the contact tank, making continuous water circulation in the system.

 The objective of the present invention is to develop a method of water purification, allowing simultaneous processes of iron removal, decarbonization with partial softening of water, as well as carry out conditioning of water by ion stabilization.

 The problem is solved by the described method of water purification and conditioning, including the treatment of water with atmospheric oxygen in a liquid-gas ejector with a multi-nozzle nozzle when water is supplied to the ejector under pressure, providing a water supply rate of at least 25% higher than the speed of sound in the resulting equilibrium two-phase water mixture - air, subsequent filtering of the water and adding hydrochloric or sulfuric acid to the water in the ejection device.

 Preferably, air is supplied at a reduced pressure of 0.3-0.7 at.

 With a high content of iron in water and low carbonate hardness, air is supplied at a pressure of 1 atm, and with a high carbonate hardness of water and a low iron content, air is supplied under reduced pressure not exceeding 0.3 atm. The addition of hydrochloric or sulfuric acids is carried out with a closed vacuum cavity of the ejector.

The operation of the ejector under reduced pressure allows for a mode in which there is a massive release of gases dissolved in water, primarily CO ₂ , which allows efficient decarbonization of water.

Traditional methods of desalination (ionic softening according to the cation exchanger – anion exchange resin scheme or in FSD filters — filters of mixed action, reverse osmosis desalination, nanofiltration reduction of hardness salts) are not effective in relation to the frequently encountered water composition with excess carbonate hardness, since the simultaneous removal of Ca ² ions ⁺ and related HCO ₃ ^- (which occurs when these methods are used) does not allow to achieve a stable state of dissolved impurities. With subsequent prolonged standing or during boiling, the appearance of a film or a finely divided precipitate of calcium carbonate is observed. Using traditional methods, it becomes necessary to reduce the calcium content in treated water to less than 10 mg / l in order to avoid undesirable consequences, which is completely unacceptable, based on the requirements of paragraph 4.11 SanPin, according to which the calcium content in drinking water is 25-80 mg / l The proposed method is devoid of these disadvantages.

After filtration, hydrochloric or sulfuric acid is fed into the water to stabilize it, which leads to the exclusion of the above negative aspects. The amount of acid added corresponds to a pH of stable water in the range of 6.7-6.8 at an initial pH of about 7.5-8.1. In practice, to stabilize 1 m ^{3 of} water after its treatment in an ejector under the stated conditions, it is necessary to add 5.6-5.7 kg of a 2% sulfuric acid solution.

 The installation allows almost instantly to carry out the substitution reaction in a solution of bicarbonate ions for sulfate ions in a predetermined amount, providing stable properties of water when standing and boiling.

To stabilize 30 m ^{3 of} water, 170 liters of a 2% sulfuric acid solution must be added. The process is carried out continuously. Since the high-speed modes of mixing the acid and water solution in the ejector are several orders of magnitude superior to mixing with conventional methods — a small vacuum is maintained in the installation (up to 0.05 MPa), the carbon dioxide from the air does not have time to shift the equilibrium in the opposite direction, but the precipitated gas free carbon dioxide is immediately removed to the atmosphere.

 As a result of these two operations, water is obtained that maximally preserves the natural salt balance of the source water of the well in the absence of sediment during its boiling.

 Example.

 The proposed method is implemented on the installation, a diagram of which is shown in the drawing. The installation comprises a unit 1, consisting of a water supply line, three sequentially installed cleaning stages, each of which contains an ejector (E1), a tank (B), a pump (H) and a water supply pipe to the next stage. At the same time, each of the three ejectors is connected by a common tube to each other and to a manometer and a crane installed in series. At the exit from block 1, two microfilters (F1 and F2) are installed. In addition, the installation comprises a block 2, consisting of an ejector of an ejector acid (E2), a tank (B), a pump (H) and a water discharge line.

Installation works as follows. The purified water is supplied to the first ejector (E1) under a pressure of at least 0.4 MPa, which ensures a water supply speed of 28.51 m / s with a sound velocity in the two-phase mixture equal to 21.4 m / s, and from it to the tank ( B), from which the pump (H) serves on the second ejector, etc. At the same time, air is supplied through a tap (Cp) to a tube connecting the ejectors. Using a manometer (M), the pressure of the air entering the ejectors is not more than 0.03 MPa. After passing through 3 stages of purification (which takes 30 minutes), ensuring a water supply rate of 25-30% higher than the speed of sound in the mixture, the water is sent to the filtration to remove the precipitated CaCO ₃ . In 1 m ^{3 of} filtered water, 5.6 l of a 2% sulfuric acid solution are injected with a dispenser and sent to an ejector (E2), which ensures their high-quality mixing. Water from the ejector is sent to the tank, from which the pump is removed from the installation.

 The results of water treatment are shown in the table.

Check by boiling the source and conditioned water showed that in the source after boiling a precipitate of CaCO _{3 was formed} . After processing in the claimed mode, the water retained its taste characteristics, turned out to be stable when standing, and when boiling, precipitation was not observed.

Sources of information
1. Patent RU 2174100, 2001.

 2. Patent RU 2177449, 2001.

 3. Patent RU 2132004, 1998.

 4. Patent RU 2034799, 1995.

 5. Patent RU 2181109, 2001.

 6. Patent RU 2119892, 2001.

Claims (5)

 1. The method of purification and conditioning of water, comprising treating the water with atmospheric oxygen using an ejector followed by filtering, characterized in that the treatment is carried out in a liquid-gas ejector with a multi-nozzle nozzle when supplying water to the ejector under pressure, providing a water flow rate of not less than 25% higher than the speed of sound in the resulting two-phase water-air mixture, and after filtration, hydrochloric or sulfuric acid is added to the water in the ejection device.  2. The method according to p. 1, characterized in that the air is supplied to the ejector under reduced pressure equal to 0.3-0.7 at.  3. The method according to claim 1, characterized in that with a high content of iron in water and low carbonate hardness, air is supplied under atmospheric pressure.  4. The method according to claim 1, characterized in that at high carbonate hardness of water and a low iron content, air is supplied at a pressure not exceeding 0.3 ata.  5. The method according to claim 1, characterized in that the addition of hydrochloric or sulfuric acid in the ejection device is carried out with a closed vacuum cavity of the ejector.

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