RU2295684C1 - Method of the steam precipitation in the water-cooling tower - Google Patents

Abstract

FIELD: heat and power industry; other industries; methods of the steam precipitation in the water-cooling towers.

SUBSTANCE: the invention is pertaining to coagulation of the steam in the water-cooling tower of the combined heat and power plants. The method of the steam precipitation in the water-cooling tower supplied with the tank and the spraying device provides, that in the water-cooling tower install at least one holder with audio transducers of noise composed out of the quarter-wave resonators arranged in parallel to each other, feed the service water to the spraying device for chilling by the cold air with formation of the steam, excite the noise in the sound frequency band by drop of the service water trickles in the tank and route it up to in the water-cooling tower, conduct conversion of the low-frequency noise into the ultrasound, using at least one audio transducer from the quarter-wave resonators form the ultrasonic standing waves on the length of the section, equal to the length of the audio transducer of the noise of the quarter-wave resonators, make concretion of the steam droplets in the ultrasonic standing waves, make precipitation of the droplets of the service water under action of the own mass after the steam coagulation in the form of the water trickles in the tank. The invention allows to increase efficiency of the combined heat-and-power plant due to reduction of the power consumption for the plant own needs and the decreased surge of the steam into the atmosphere.

EFFECT: the invention ensures the increased efficiency of the combined heat-and-power plant due to reduction of the power consumption for the plant own needs and the decreased surge of the steam into the open air.

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Description

The invention relates to the field of aerosol coagulation, in particular to steam coagulation in a cooling tower of combined heat and power plants.

Known methods of cooling warm water flowing from a height in small streams due to evaporation [1].

The disadvantage of this method is the appearance of steam, followed by its release into the atmosphere.

The closest in technical essence is the method of acoustic coagulation - the process of approximation and enlargement of liquid droplets suspended in a gas under the influence of acoustic vibrations of sound and ultrasonic frequencies [2]. Coagulation results in the deposition of liquid droplets suspended in a gas (aerosol).

The small size of the aerosol particles is the reason for their great mobility: the particles participate in Brownian motion, are carried away by convective flows. When a sound field is applied, additional forces arise that contribute to coagulation: a particle suspended in a gas is involved in vibrational motion, the pressure of sound radiation acts on it, causing it to drift, and it is carried away by acoustic currents.

Acoustic coagulation is practically used to precipitate industrial dust, smoke and fog. The sound field is usually created by sirens or whistles.

The degree and speed of gas purification by acoustic coagulation is mainly determined by: 1) sound intensity I (noticeable coagulation begins at I ~ 0.01 W / cm ² and intensifies with a further increase in I; for practical use, an intensity I> 0.1 W / cm ² ); 2) the exposure time, which depends on I (at I = 1.0 W / cm, the entire coagulation process proceeds within a few seconds); 3) frequency f (in practice, acoustic oscillations of a frequency of 0.5-20 kHz are usually used); 4) the initial concentration of aerosol (the use of the coagulation method is rational at a concentration of ≥1-2 g / cm ³ , with increasing concentration, the efficiency of coagulation increases) [2].

The disadvantage of this method (in the case of modern methods of exciting sound vibrations - sirens or whistles) is that acoustic coagulation is carried out by the sound intensity I> 0.1 W / cm ² .

The task is the deposition of steam in the tower and increasing the efficiency of the cogeneration plant by reducing energy consumption for own needs and reducing the emission of steam into the atmosphere.

The technical result is achieved by the fact that in the method of vapor deposition in a cooling tower equipped with a reservoir, an irrigation device and a technological path, the following is provided: a) at least one ferrule with acoustic noise converters from quarter-wave resonators located at a given distance is produced on the technological path in the cooling tower parallel to each other; b) supply process water to the irrigation device for cooling with cold air with the release of steam; c) the noise in the sound frequency range is excited by the fall of technical water streams into the tank and directs it up to the cooling tower; g) carry out the conversion of low-frequency noise into ultrasound by at least one acoustic transducer of quarter-wave resonators; e) form ultrasonic standing waves at a length equal to the length of the acoustic noise transducer from quarter-wave resonators; f) produce coagulation of vapor droplets in ultrasonic standing waves; g) precipitate droplets of industrial water under the action of its own weight after coagulation of steam in the form of water streams in the tank.

Comparative analysis with the prototype shows that in the claimed method of acoustic coagulation of steam in the tower using ultrasonic vibrations converted from low-frequency noise of the tower. The oscillator is a composite acoustic noise converter of quarter-wave resonators, which is located in the space between the resonators.

Thus, the present invention meets the criterion of "Novelty."

Comparison of the claimed solution with other technical solutions shows that acoustic coagulation of liquid droplets (steam) is known [2]. However, it is not known that ultrasound can be created using an acoustic noise transducer from quarter-wave resonators during operation of the cooling tower, with the creation of standing waves, coagulation of liquid droplets and their deposition into the tank.

Thus, the present invention meets the criterion of "Inventive step".

Key Points

The main provisions of the physical essence for the implementation of the method of acoustic coagulation of steam in a cooling tower (tower cooler):

1. The presence of constant noise in the tower, propagating upward from the tank.

2. The source of low-frequency noise is droplets and streams of chilled liquid falling from a height into the reservoir.

3. Convert low-frequency noise to ultrasound.

4. The conversion of low-frequency noise into ultrasound is carried out by two acoustic transducers of quarter-wave resonators located at a given distance parallel to each other in a cage.

5. The formation of ultrasonic standing waves is carried out at a length equal to the length of the acoustic noise transducer from quarter-wave resonators.

6. Using the phenomenon of the physical process of acoustic coagulation of steam (liquid droplets) with a standing wave, followed by their deposition into the reservoir.

We show the possibility of using acoustic coagulation of steam (liquid droplets) with ultrasonic standing waves in a clip.

1. Waves and vibrational velocity.

The wave equation describing the elastic perturbation has the form [3]:

A particular solution to equation (1) is

where a is the displacement of a particle of the medium relative to the resting position; A is the amplitude of the bias; Ω is the angular frequency; t is time.

Expression (2) describes a plane harmonic wave of frequency f = ω / 2π propagating in the positive direction of the x axis.

Differentiating (2) with respect to t, we obtain the expression for the velocity of a particle of the medium - the so-called vibrational velocity

Therefore, the amplitude of the vibrational velocity

The value of U determines the maximum speed with which particles move in the process of oscillation.

According to expression (4), the particle velocity fluctuates between this quantity and zero.

2. The interference of waves. Standing waves.

Phenomena associated with the simultaneous existence of several oscillations at some point in the medium are called interference.

Interference phenomena play an important role in the emission of sound.

A particularly important role is played by interference in the propagation of two identical waves in opposite directions. Oscillations propagating in the positive and negative directions along the x axis can be written as:

Applying the addition theorem, we obtain for the resulting standing wave the expression

from which it directly follows that at the points at which Cos (2πx / λ) vanishes, the displacement a is identically equal to zero; this occurs when x is an odd number λ / 4. In the middle between these points are the points at which Cos (2πх / λ) is maximal in absolute value; here, the amplitude of the displacement in the standing wave is twice the amplitude in the initial traveling waves.

We find the expression for the vibrational velocity in a standing wave, differentiating the expression

Thus, the nodes and antinodes of the vibrational velocity are located at the same points as the nodes and antinodes of the bias.

3. Pressure in a standing wave.

We now turn to the question of the distribution of pressure in a standing wave. In a wave propagating in the direction of the x-axis forces, the pressure p is proportional to the change in displacement along x, i.e. value da / dx. Differentiating expression (7) with respect to x, we obtain

Thus, in a standing wave and sound pressure contains nodes and antinodes; however, the location of the pressure nodes coincides with the position of the displacement antinodes, and vice versa. The pressure amplitude in the antinodes is twice the amplitude in the initial traveling waves [2].

4. Acoustic coagulation.

It has long been known that under the influence of sound vibrations between particles oscillating in a sound field, attractive and repulsive forces can arise. For spherical particles, this process was experimentally and theoretically investigated by Koenig [4] in connection with the work of Bjerkness [5]. Partially, the appearance of dust figures in Kundt tubes is based on this phenomenon.

Brandt and Freund [6] and Brand and Gideman [7] showed that under the action of ultrasonic waves in aerosols, coagulation and sedimentation of particles instantly occur.

Brandt and Freund studied the details of the process of settling particles by microphotography under illumination using the dark field method.

Based on these experiments, Brandt and Gideman distinguish two stages of coagulation. At the beginning, the particles take part in the oscillatory process and follow the motion of the fluid between the antinodes and the vibration nodes. Moreover, as a result of collisions and under the action of forces of mutual attraction, they stick together and increase in size. In the second stage, the enlarged particles no longer follow sound vibrations, but make random motions, and as a result of new mutual collisions and collisions with smaller particles, their sizes continue to increase, and then precipitate.

5. Coagulation of steam (droplets of liquid) in a standing wave.

Let there be a droplet of liquid with radius R and density ρ in air with a dynamic viscosity η oscillating with amplitude U _B and frequency f.

According to Stokes’s law [3], the friction force acting on a droplet

where Δυ is the velocity difference between droplets and air.

According to formula (10), the droplet velocity

The droplet motion is described by the differential equation

or

The general solution to this equation has the form [2]

A non-periodic term represents a transient. It can be neglected, since coagulation occurs after a time when the transition process no longer has any effect.

Thus, the amplitude of the droplet

The degree of particle participation in the sound vibrations of the medium (the so-called drag coefficient) in the case of a standing sound wave is determined by the relation

The ratio of the amplitudes X _K / U _B will be the smaller, the larger the radius of the droplet and the higher the frequency.

Thus, for the degree of participation of the droplet in fluid oscillations, the value of R ² f is decisive.

If we take the value of X _K / U _B = 0.8 beyond the border to which the droplets are still carried away by sound vibrations, then from the relation

we get

The value of Z determines the degree of participation of the droplet in fluid oscillations.

Thus, relation (18) allows one to calculate the frequencies necessary to create standing waves in order to coagulate droplets and then precipitate them.

According to the above provisions of the physical essence, acoustic coagulation of droplets is achieved.

Figure 1 shows a diagram of a cooling tower with technological elements; figure 2 shows the arrangement of clips with acoustic noise converters from quarter-wave resonators on the technological path; figure 3 shows the layout of acoustic noise converters from quarter-wave resonators in a ferrule and the coagulation process in a standing wave of steam.

Figure 1 shows: 1 - cooling tower, 2 - technological path, 3 - irrigation device, 4 - reservoir, 5 - noise, 6 - drop of water streams into the reservoir, 7 - pipe for supplying warm industrial water for cooling, 8 - clip with acoustic noise converters from quarter-wave resonators, 9 - pairs, 10 - steam emission from the cooling tower;

Figure 2 shows: 1 - cooling tower, 2 - technological path, 8 - clip with acoustic noise converters from quarter-wave resonators, 11 - first acoustic noise converter from quarter-wave resonators, 12 - second acoustic noise converter from quarter-wave resonators.

Figure 3 shows: 8 - clip with acoustic noise converters from quarter-wave resonators, 9 - pairs, 11 - first acoustic noise converter from quarter-wave resonators, 12 - second acoustic noise converter from quarter-wave resonators, 5 - direction of sound propagation from falling water jets into the reservoir, 14 — precipitation of water droplets after coagulation of steam in a standing ultrasonic wave in the form of water streams, 15 — sound pressure in a standing wave, 16 — vibrational velocity in a standing wave.

An example implementation of the method.

First operation. At least one ferrule 8 (Fig. 1) is installed on the technological path 2 (Fig. 1) in cooling tower 1 with acoustic noise converters from quarter-wave resonators located at a given distance parallel to each other;

Second operation. Technical warm water is supplied through a pipe 7 (Fig. 1) to an irrigation device 3 (Fig. 1) for cooling with cold air, as a result of which steam 9 (Fig. 1) is released.

The third operation. Excite the fall of 6 jets of industrial water (figure 1) into the reservoir 4 (figure 1) noise 5 (figure 1. And figure 3) in the audio frequency range and direct it up to the cooling tower 1 (figure 1).

The fourth operation. The low-frequency noise is converted into ultrasound by at least one acoustic transducer of quarter-wave resonators 11 and 12 (Fig. 3) located at a predetermined distance parallel to each other in the cage 8 (Fig. 3).

Fifth operation. Ultrasonic standing waves are formed at a length equal to the length of the acoustic noise transducer from quarter-wave resonators 11 and 12 (Fig. 3).

Sixth operation. Acoustic coagulation is performed in ultrasonic standing waves using the following parameters: sound pressure 15 in a standing wave and vibrational velocity 16 in a standing wave (Fig. 3) by moving droplets of steam 9 (Fig. 3) from the antinode of pressure wave 15 into the antinode of vibrational velocity 16 .

Seventh operation. Water droplets are precipitated under their own weight after coagulation of steam in the form of water jets 14 (FIG. 3) into the reservoir 4 (FIG. 3).

Information sources

1. Brief Polytechnical Dictionary. - M.: Gostekhizdat. 1956.-S. 246.

2. Ultrasound. Little Encyclopedia. Chap. Ed. I.P. Golyamin. - M .: Soviet Encyclopedia. 1979. - S. 161-162 (prototype).

3. Bergman L. Ultrasound and its application in science and technology. IL - M .: IL, 1957. - S.23-25, 489-491, 495-497. (prototype).

4. König W., Hydrodynamisch-akustische Untersuchungen, Ann. d. Phys. (3), 42,353,549 (1891).

5. Bjerknes S.A. Remarques historiques sur la theori du mouvement d′un ou de plusieurs corps, de formes constantes ou variables, dans un fluide incompfessible; sur les forces apparentes, qui en resultent et sur les experiences qui s'y rattachent, Compt. Rent, 84, 1222, 1309, 1375, 1446, 1493 (1867).

6. Brandt., Über das Verhalten von Schwebstofen in schwingen Gasen bei Schall- und Ultraschallfrequenzen, Kolloid / Zs., 76, 272 (1936).

7. Brandt O., Hiedenmann E., Über das Verhalten von Aerosolen im akustischen Feld, Kolloid. Zs., 75, 129 (1936).

Claims (1)

A method of vapor deposition in a tower equipped with a tank and an irrigation device, which consists in installing at least one cage with acoustic noise converters from quarter-wave resonators parallel to each other, supplying technical water to the irrigation device for cooling with cold air with the release of steam, the noise in the sound frequency range is excited by the fall of technical water streams into the tank and directs it up into the cooling tower, low ultrasonic frequency waves to ultrasound by at least one acoustic transducer from quarter-wave resonators generate ultrasonic standing waves at a length equal to the length of the acoustic noise transducer from quarter-wave resonators, coagulate vapor droplets in ultrasonic standing waves, and precipitate droplets of process water under their own weight after coagulation of steam in the form of streams of water into the tank.

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