RU2467956C1 - Method of water treatment - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to water treatment for reduction the content of salts and suspended substances. Proposed method comprises filling the tank with water to effect acoustic cavitation to level of 0.15-0.5 in evacuating the tank to 0.3-0.9 kgf/cm² accompanied by filtration. Cavitation is caused by simultaneous action of ultrasound different-frequency opposed oscillators. Low-frequency oscillator excites broad spectrum of frequencies while high-frequency oscillator excites one oscillation frequency ten times higher than that of low-frequency oscillator main frequency. In compliance with preferable version, main oscillation frequency excited by low-frequency oscillator makes 1.8 kHz while that caused by high-frequency source makes 18 kHz.

EFFECT: intensified treatment, deep cleaning.

4 cl, 1 dwg, 1 ex

Description

The invention relates to the field of water purification and aqueous solutions using ultrasonic oscillatory systems.

There is a method according to which desalination of water is carried out when exposed to the flow of desalinated water by a magnetic field and elastic waves of ultrasonic frequency, where the frequency is set above 100 kHz (RU 2120415, 20.10.1998).

However, with this treatment, the inner surface of the magnets is constantly coated with salts that reduce the magnetic permeability, which leads to a decrease in the efficiency of desalination.

A known method for the preparation of drinking water, which produce ultrasonic treatment with a field with an intensity of (1 ÷ 70) · 10 ⁴ W / m ² created by a hydrodynamic generator, and at the same time supply oxygen-containing gas (RU 2333156, 09/10/2008).

There is also a known method of wastewater treatment, including mechanical treatment, physico-chemical treatment, sedimentation, biological treatment, in which physico-chemical treatment is carried out by treating water with electrocoagulation, combined with periodic exposure to ultrasonic vibrations with a frequency of 20-25 kHz at a power of 1-3 V / cm ² (RU 2328455, 07/10/2008).

The disadvantages of this method are the low degree of purification of water containing an increased concentration of difficultly oxidized substances, high energy consumption and the need for disposal of waste generated.

The closest in technical essence and the achieved result is a method of treating water and aqueous solutions, including adjusting the pH by repeatedly decreasing the pressure of a high-pressure liquid by its recirculation to the value at which cavitation occurs, followed by increasing the pressure to the value at which cavitation ceases after whereby the recirculated liquid is heated, and part of the high-pressure liquid is taken for filtration, cavitated is taken from the remaining recirculated stream Fluid is heated to its collapsing cavitation bubbles and deposition of solids formed, and then returned to the conditioned fluid in the low pressure recycle stream. Cavitation is carried out by a hydrodynamic or ultrasonic method (RU 2240984, 11.27.2004).

The known method allows to expand the functionality due to the integrated preparation of the liquid (softening, disinfection, reducing the content of salts and suspended particles). However, this method is quite complex, lengthy and energy intensive.

The objective of the present invention is to intensify and simplify the process of preparing water and aqueous solutions to obtain a purified aqueous medium.

The problem is solved by the described method of purification of an aqueous medium, which includes filling the container with aqueous medium, treating the medium in said container under reduced pressure with acoustic cavitation by simultaneously exposing the aqueous medium to sources of ultrasonic vibrations of different frequencies directed towards each other, using a low-frequency source , exciting a wide range of frequencies, and a high-frequency source, exciting one oscillation frequency, the value of which is 10 times higher the magnitude of the fundamental harmonic of the low-frequency source is increased, the processing is carried out when a vacuum of 0.3-0.9 kgf / cm ^{2 is} created in a container filled with an aqueous medium, and the process is carried out until a cavitation index of 0.15-0 is reached in the medium being treated , 5, and subsequent filtration of the treated aqueous medium.

Preferably, the low-frequency and high-frequency sources are mounted coaxially in the vessel at a distance between them equal to 1/4 of the wavelength of the low-frequency source.

Preferably, the container is filled with aqueous medium to a height equal to 1/2 of the wavelength of the low-frequency source.

Preferably, the main oscillation frequency generated by the low-frequency source is 1.8 kHz, and the oscillation frequency created by the high-frequency source is 18 kHz.

To implement this method as a source of low-frequency oscillations, you can use a sonar emitter "knife type". As sources of high-frequency oscillations, you can use a magnetostrictive transducer. At the declared location of the mentioned oscillation sources, the acoustic fields arising in the aqueous medium are directed coaxially to each other, due to which an avalanche-like cavitation is created in the container with the liquid, which leads to effective degassing. The gas is removed from the tank continuously and is ensured by carrying out the process at the stated vacuum interval. A decrease in vacuum below 0.3 kgf / cm ² reduces the degree of degassing, and an increase above 0.9 kgf / cm ² unnecessarily increases energy consumption. The presence of avalanche cavitation in the acoustic field in the presence of vacuum leads to a sharp break in intermolecular bonds and a decrease in the viscosity of the aqueous medium. The claimed cavitation index created in the treated aqueous medium leads to a decrease in the viscosity of the liquid (without heating) by 30-50%, which allows subsequent filtration to reduce the duration of this stage and increase the volume of filtered water by 20-25% per unit time. For filtering, you can use various devices, based on the composition of the processed fluid and the requirements for the target product. At the final stage of the process, microfiltration, ultrafiltration, reverse osmosis, and the like can be performed.

The implementation of the invention is carried out on a simple installation, one of the possible schemes of which is shown in figure 1, where

1 - pipeline for supplying water;

2 - pressure gauge;

3 - sonar emitter of low frequency;

4 - high frequency ultrasonic emitter;

5 - capacity;

6 - pipeline for removing gas from the system;

7 - pipeline for supplying water to the pump;

8 - high pressure pump;

9 - pressure gauge for applying pressure to the filtration;

10 - connecting pipe high pressure;

11 - membrane filters installation reverse osmosis;

12 - pipeline for draining filtered water.

Example.

The initial contaminated water containing hardness salts, at a pressure of 3 atm, is supplied through a pipeline to a vessel, the volume of which is 26 × 10 ^-3 m ³ , to a “knife-type” low-frequency sonar emitter mounted on the vessel’s inner wall. The performance of the selected emitter is 3.6 m ³ / hour. The capacity is filled to a height equal to 1/2 of the wavelength of the low-frequency source, which is approximately 37-40 cm. On the opposite side of the capacity, a magnetostrictive transducer (high-frequency ultrasonic emitter) of the ПМС15А18 brand is fixed, the power of which is supplied through a generator of the УЗГ- brand 2-4 m. The distance between the emitters is 1/4 of the wavelength of the low-frequency source, which is approximately 19-20 cm. At the same time, the emitters are turned on. The intensity of the low-frequency oscillations (fundamental frequency 1.8 kHz) is 3-4 W / cm ² . The intensity of the high frequency oscillations (18 kHz) is 8-10 W / cm ² . Due to the combined influence of the acoustic fields created by the said emitters and directed towards each other, powerful cavitation occurs in the treated water (cavitation index 0.35) and degassing begins. The evolved gas is pumped out through line 6 when creating 0.6 kgf / cm ² in the discharge tank. Treated water, the viscosity of which decreased by 40%, is removed from the tank with a flow rate of 1 l / s and, when the pump 8 is turned on, it is fed through pipeline 10 to the reverse osmosis unit for filtration under a pressure of 8-15 atm. The filtered liquid, in which the salt content and the amount of suspended impurities are reduced to sanitary standards, is supplied to the consumer through a pipe 12 for draining the filtered water.

When comparing the results of the claimed method with the results of a method that does not involve cavitation, as described above, the viscosity of the water does not decrease, therefore, when filtering on a similar reverse osmosis unit (grade R070), water must be supplied under high pressure (from 11 to 17 atm).

As can be seen from the description, in comparison with the prototype of the claimed method leads to the possibility of increasing the volume of filtered water by reducing its viscosity without heating, allows filtering at a lower pressure, reduces energy costs for the process as a whole. Thus, the invention allows to intensify the processing of liquid media while maintaining a high degree of purification.

Claims (4)

1. A method of purifying an aqueous medium, including filling the container with aqueous medium, treating the medium in said container under reduced pressure with acoustic cavitation and subsequent filtering, characterized in that cavitation is provided by simultaneously exposing the aqueous medium to sources of ultrasonic vibrations of different frequencies directed towards each other to a friend, they use a low-frequency source that excites a wide range of frequencies, and a high-frequency source that excites one oscillation frequency, Jicin which is 10 times the magnitude of the fundamental frequency vibrations generated by the low frequency source, processing is performed to create a container filled with an aqueous medium, the dilution equal to 0.3-0.9 kgf / cm ^2, and the process is carried out to achieve in the treated medium index cavitation equal to 0.15-0.5. 2. The method according to claim 1, characterized in that the low-frequency and high-frequency sources are installed coaxially in the vessel at a distance between them equal to 1/4 of the wavelength of the low-frequency source. 3. The method according to claim 1, characterized in that the tank is filled with aqueous medium to a height equal to 1/2 the wavelength of the low-frequency source. 4. The method according to claim 1, characterized in that the main oscillation frequency generated by the low-frequency source is 1.8 kHz, and the oscillation frequency created by the high-frequency source is 18 kHz.

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