RU2339888C1 - Method of steam deposition in cooling tower - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: method of steam deposition in cooling tower equipped with reservoir and irrigation system includes the following operations: dynamic loudspeakers are installed along circumference inside cooling tower above the irrigation system; service water is supplied to irrigating device for cooling by cold air with steam discharge; sound is excited by drop of service water trickles into reservoir and sent upwards into cooling tower; sound is generated towards each other with dynamic loudspeakers that are installed diametrically opposite along cooling tower circumference; identical frequencies that are excited by drop of service water jets into reservoir in sound range of frequencies are summed up according to amplitude to frequencies generated by dynamic loudspeakers; standing sound waves are created in space between dynamic loudspeakers, steam coagulation is performed in standing sound waves located between dynamic loudspeakers; steam drops are deposited in the form of water trickles, into reservoir under effect of their own weight after process of coagulation.

EFFECT: increase of heat and power plant efficiency factor due to reduction of energy consumption for auxiliary needs and reduction of steam discharge into atmosphere.

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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 is} required; exposure time, which depends on I (at I = 1.0 W / cm ^{2, 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 the method of vapor deposition in a cooling tower equipped with a tank, an irrigation system, which includes the following operations: a) - arrange dynamic loudspeakers around the circumference inside the tower above the irrigation system; b) - supply process water to the irrigation device for cooling with cold air with the release of steam; c) - the sound is excited by the fall of trickles of industrial water into the tank and directs it up into the cooling tower; d) - generate towards each other sound by dynamic loudspeakers located diametrically opposite to the circumference of the tower, e) - sum the same frequencies in amplitude, excited by the fall of technical water jets, into the reservoir in the sound frequency range with frequencies generated by the dynamic loudspeakers; f) - create standing sound waves in the space between the dynamic loudspeakers; g) - produce coagulation of steam in the standing sound waves located between the dynamic loudspeakers; f) - produce the precipitation of droplets of steam, in the form of streams of water, into the tank under the action of its own weight after the coagulation process.

Comparative analysis with the prototype shows that in the claimed method of acoustic coagulation of steam in a cooling tower, total sound vibrations are used, on the one hand, these are vibrations generated by dynamic speakers diametrically spaced around the circumference of the cooling tower, and on the other hand, is the sound created by the fall of water jets in storage tank.

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

A comparison of the claimed solution with other technical solutions shows that the acoustic coagulation of liquid droplets (steam) is known (sirens and whistles with an intensity of more than 0.1 W / cm ^{2 are used} ) [2]. However, it is not known that standing sound waves can be created in the tower space using dynamic loudspeakers and coagulation of steam (water droplets) in standing waves followed by their deposition into the reservoir (therefore, there is no need to create sound intensities of more than 0.1 W / cm ² ).

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

We show the possibility of using acoustic steam coagulation (water droplets) by standing sound waves created in the space of the cooling tower.

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

2. The sound source is a drop of water droplets and streams of chilled liquid from a height in the tank.

3. Generation of sound frequency into the space of the tower by sound emitters - dynamic loudspeakers.

4. The creation of standing sound waves in the space between the dynamic loudspeakers located diametrically opposite along the inner circumference of the tower.

5. Using the phenomenon of the physical process of acoustic coagulation of steam (water droplets) by standing sound waves, followed by their deposition into the tank.

The rationale for the method.

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 = 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 for the particle velocity 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 Cos (2πх / 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. the value of d a / 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 antinodes is twice the amplitude in the initial traveling waves [3].

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]. Particularly, the occurrence 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. First, 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 (water droplets) 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]

The non-periodic term represents the 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 us to calculate the frequencies necessary to create standing sound waves in order to coagulate water droplets with their subsequent sedimentation.

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 location in the tower of the sound emitters - dynamic speakers; figure 3 shows a diagram of the formation of a standing wave between two sound emitters - dynamic loudspeakers diametrically located in the tower, and the coagulation process in a standing wave of steam (liquid droplets).

Figure 1 shows: 1 - cooling tower, 2 - steam (water droplets), 3 - pipe for supplying heated water to the cooling tower for cooling, 4 - irrigation device, 5 - drop of water streams into a tank filled with chilled water, 6 - tank - a sound generator (sound is created due to the interaction of falling water jets with the surface of the water in the tank), 7 - a sound frequency generator (for example, a generator of type G3-34), 8 - sound emitters - dynamic speakers (for example, a loudspeaker of type 10GD18) .

Figure 2 shows: 1 - cooling tower, 8 - sound emitters - dynamic speakers, 9 - standing sound wave (fragment), formed between two sound emitters, dynamic loudspeakers diametrically located in the tower.

Figure 3 shows: 2 - steam (water droplets), 8 - sound emitters - dynamic loudspeakers, 9 - standing sound wave (fragment) formed between two sound emitters, dynamic loudspeakers diametrically located in the cooling tower, 10 - steam movement ( water droplets).

An example implementation of the method.

First operation. The dynamic loudspeakers 8 (Fig. 1) are placed around the circumference inside the cooling tower 1 (Fig. 1) above the pipe 3 (Fig. 1) and the irrigation system 4 (Fig. 1).

The second operation. Technical heated water is supplied through a pipe 3 (FIG. 1) to an irrigation device 4 (FIG. 1) for cooling with cold air, as a result of which steam (water droplets) 2 (FIG. 1) is released.

The third operation. Excite the fall of the jets 5 (figure 1) of industrial water into the reservoir 6 (figure 1) sound (in a wide range of sound frequencies) and direct it to the top in the cooling tower 1 (figure 1).

The fourth operation. Generate sound towards each other from the sound emitters - dynamic speakers 8 (figure 1 and figure 2) (diametrically located loudspeakers around the circumference of the tower).

Fifth operation. The same frequencies are summed in amplitude, excited by the fall of the jets 5 (Fig. 1) of industrial water into the reservoir 6 (Fig. 1) in the sound frequency range with the frequencies generated by the sound emitters - dynamic loudspeakers 8 (Fig. 3), located diametrically opposite to the circumference cooling tower 1 (figure 1).

Sixth operation. Create standing sound waves 9 (figure 3) (shows the total amplitude of the same frequencies generated by the sound emitters - dynamic speakers 8 (figure 3), and trickles of water 5 (figure 1) when they fall into the tank 6 (figure 1) ) in the space between the dynamic loudspeakers 8 (Fig.3), located diametrically opposite along the inner circumference of the tower 1 (Fig.2).

Seventh operation. Coagulate water droplets 2 (Fig. 3) (moving water droplets up 10 (Fig. 3) in cooling tower 1 (Fig. 1) in standing sound waves 9 (Fig. 3) (using parameters: sound pressure and vibrational velocity in standing wave 9 (figure 3).

The eighth operation. Deposited water droplets 11 (FIG. 3) are deposited in the reservoir 6 (FIG. 1) after the coagulation process in standing sound waves 9 (FIG. 3) in the form of streams 12 (FIG. 3) under the action of their own weight.

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. - 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 C.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., Ü ber das Verhalten von Schwebstofen in schwingen Gasen bei Schall- und Ultraschallfrequenzen, Kolloid / Zs., 76, 272 (1936).

7. Brandt O., Hiedenmann E., Ü ber 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, an irrigation system, comprising the following operations: a) they arrange the placement of dynamic loudspeakers in a circle inside the cooling tower above the irrigation system; b) supply process water to the irrigation device for cooling with cold air with the release of steam; c) the sound is excited by the fall of technical water streams into the tank and directed to the top of the cooling tower; d) generate towards each other sound dynamic loudspeakers located diametrically opposed to the circumference of the tower; e) sum in amplitude the same frequencies excited by the fall of technical water jets into the reservoir in the sound frequency range with frequencies generated by dynamic speakers; f) create standing sound waves in the space between the dynamic loudspeakers; g) produce coagulation of steam in standing sound waves located between the dynamic loudspeakers; f) vapor droplets are precipitated in the form of streams of water into the tank under the action of their own weight after the coagulation process.

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