SU1507432A1 - Method of producing variable foaming ratio foam - Google Patents

Abstract

The invention relates to the preparation of foams and can be used in various industries. The goal is to increase the range of adjustment of the foam ratio and reduce energy consumption. For this purpose, the starting foam is contacted with a foreign gas differing in partial pressure and solubility from the gas contained in the bubbles of the initial foam. It is more advisable to sequentially contact the foam with several foreign gases in order to increase or decrease their solubility. 1 hp ff, 2 ill.

Description

This invention relates to a foaming technique and may find application in the chemical and other industries.

The purpose of the invention is to increase the range of adjustment of the foam ratio and reduce energy consumption.

FIG. Figure 1 shows a graph of the change in the radius of a single foam foam when it is in contact with a foreign gas; in fig. 2 is a graph of the change in the radius of a bubble of foam when it is subsequently contacted with several (in this case, two) foreign gases.

The method is carried out according to the following technology.

The foam obtained by mechanical mixing of the foaming solution and air (or other gas) is fed to the object (it is either a form for producing foam material or another object that is coated with foam). If it is necessary to obtain a high-fold foam, it is supplied in the presence of a gas that has a significant specific solubility and a partial pressure different from the original. Such a gas spreads almost instantaneously in a liquid that forms foam films.

The proposed mechanism for changing the multiplicity is developed according to the following scheme. Two regions with substantially different partial pressures of a highly soluble gas (e.g., CO) are separated by a liquid layer — the wall of a foam bubble. At the boundaries of the liquid phase with the gas regions, an equilibrium is instantly established along the span

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4 :: Oud Yu

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voronnogo gas phase corresponding to each of the partial pressures (Henry's law). Thus, at the boundaries of a thin layer of liquid, substantially different values of the concentration of the dissolved gas are maintained. This leads to a powerful diffusive flow of gas through the interlayer.

and, consequently, to the rapid attack of the bubble by gas from the outer region. It should be noted that there is a counter-current (air) in the outer region. However, with significantly worse solubility (the solubility of nitrogen and oxygen in water is about 3 orders of magnitude lower than the solubility of CO), this diffuse flux is an appropriate number of times weaker, i.e. a bubble picks up gas hundreds of times faster than it loses (if CO is contained in the bubbles of the original foam, then contact with air will reduce the magnification). Further, in a similar manner, bubbles that lie in the depth of the foam layer are gradually included in the process, which results in an increase in its total multiplicity. In practice, it is not only the fact of an increase in the multiplicity of the foam layer that is important, but also Yrem, during which this increase turns out to be significant, for example, twofold.

Taking into account the equation for the change in mass

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Рр R К - РИ - РЬГС5

0

Mp is the average molecular weight of the solution (molecular weight of the solvent), kg / kmol} density of the solution (for low concentrated solutions the density of the solvent), kg / m; universal gas constant J / kmol K; Henry coefficient, Daj external pressure, Ilaj partial pressure of gas in the initial zone. Pa. Formula (1) makes it possible to analyze the effect of various parameters on the rate of increase in multiplicity. Thus, the rate of change of the multiplicity is favorable: high solubility (small k), high initial multiplicity (large Xp), and particularly high initial dispersion of foam (small g).

From the graph in FIG. As can be seen in Figure 1, at the initial moment of time, a sharp change in the diameter of the bubble (and hence the multiplicity) occurs, and then the process slows down. Since, in view of the nature of the dependence obtained, the fastest change in the multiplicity occurs at the beginning of the process, it is possible to accelerate the change process. multiplicities. For this, it is advisable to bring the foam in a short time.

syr bubble, the law of Henry, the law of-35 in contact with another foreign gas.

the change in multiplicity, the expansion law of a bubble, one can obtain the characteristic time of a twofold increase in multiplicity

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g., 0.5 10-3 m

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0 2-10 m2 / s, Мr 18 kg / kmol, Рр 10 kg / m, And 8314 J / kmol K, T 293 K, K 1.4-U Pa, R „10 Pa, RVGO O, we get t, 3 s, which is close to the experimental evaluation.

the fraction of the surface of the bubble in contact with the external atmosphereJ the initial value of the multiplicity

Go - D foam; 55 control tank contains air

the initial radius of the bubble, MJ (oxygen partial pressure, diffusion coefficient is 0–), the capacitance

filled with pure oxygen - partial pressure, specific dissolved gas in a liquid, mchs;

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having even higher (for the sake of brevity multiplicity low) solubility (after CO / J, for example NH j). The nature of the dependence of the radius of the bubble when it is in contact with several foreign gases is presented in figure 2. For example, a portion of the 0-1 curve corresponds to the filling of an air bubble with carbon dioxide brought into contact with the bubble. If we now ensure contact of the bubble, for example, with ammonia, then the change in the radius of the bubble with time will go along the curve 1-2.

Example 1. Foam is generated by sparging a solution of a sulfonic acid with air. The time of the experiment is 500 seconds. The size of the generated bubbles 1, m, the multiplicity of 60.

4.3 tightness; -10-3 g-gas per 100 g of water. - Foaminess in the investigated container 100. The increase in the multiplicity is achieved without additional energy consumption.

Example 2. The conditions for the generation of foam are similar to those in Example 1, but the test container with a volume of 1 liter is filled with carbon dioxide. The partial pressure of carbon dioxide is 10 Pa, the specific solubility of 0.17 g gas per 100 g of water.

After 500 s after the start of the experiment in the control capacitive

These accumulated 20 ml of foam with a multiplicity of about 70 and a bubble size of 1.5 mm. At the same time, 60 ml of flax with a bubble size of 2.5 mm and a multiplicity of 200 has accumulated in the measured measuring capacity. The increase in -fraction is reached without additional energy consumption.

Example 3. Foam generation conditions are similar to the previous examples. Capacity under test is used aMNfHa com. Partial pressure 10 Pa. The solubility of ammonia 72, With g-gas in 100 g of water.

500 seconds after the start of the experiment, 20 ml of foam with a multiplicity of 70 and a bubble size of 1.1 mm accumulated in the control bottle. 80 ml of foam with a bubble size of 1.2 mm accumulated in the test container. 80 ml of foam with a size of bubbles of 2.2 mm and a multiplicity of 350 accumulated in the studied container. The increase in the multiplicity was achieved without additional energy consumption.

Example 4. Foam is generated by sparging a solution of a sulfonic acid with air. The time of the experiment is 500 seconds. The size of the generated pools is 1.0–10–3 m, the multiplicity is 60. The reference measuring capacity contains air (partial pressure of nitrogen is 0.79 10 Pa). The capacity under investigation is filled with nitrogen — the partial pressure is 10 Pa, the solubility of nitrogen is 1.89-.10 g of gas per 100 g of water (ie, less than the average solubility of air). 500 seconds after the start of the experiment (collecting the foam), it is blown with helium, the solubility of which is 1.74 -10 g-gas per 100 g of water. After these operations, the multiplicity of foam in the tank under study is 25. The change in the multiplicity of dos

crucible without additional energy costs.

Example 3. According to the method in accordance with the prototype, the foaming solution is prepared on the basis of the PO-HA frother (for fire extinguishing foams). To obtain a foam of a multiplicity of 700, a dispersant in the form of rotating grids is used, which makes it possible to achieve such a multiplicity due to the intense dispersion of a gas-liquid jet. The energy consumption for the operation of such a foam generator is

Example 6. A foaming solution was prepared analogously to example 5, a foam generator was used without a dispersant (rotating grids), therefore

0 at the outlet of the foam generator, a foam with a multiplicity of 250 is obtained. The power required to create a foam is 10 kWh. The resulting foam with a multiplicity of 250 is brought into contact with

5 with argon, the specific solubility of which is 5.01 CHO G of gas per 100 g of water, the partial pressure is 10 Pa. After that, the foam multiplicity reaches 700. Thus, 0 and the foam multiplicity are obtained, as in Example 5 (prototype) , but with less power consumption.

Example 7. A foaming solution is prepared analogously to example 6. The resulting foam (at energy consumption 10 kWh) of multiplicity 250 is first brought into contact with argon and then blown with carbon dioxide, the solubility of which is 0.169 g-gas per 100 g of water, partial pressure 10 Pa. The result is a foam with a multiplicity of 1100. Thus, when the energy consumption of Mens (compared with the prototype, according to example 6) is obtained

5 a significant increase in the multiplicity.

Since the multiplicity of the produced foam according to the proposed method is determined mainly not by the method of generating the foam, but by the presence of gas with

0 with a high specific solubility, this allows one to obtain high-expansion foams using the simplest ejection foam generators, which differs by simplicity, low metal capacity, and the absence of rotating parts.

To obtain high-expansion foams in accordance with the proposed fy method, it is sufficient to cover or make a finished product.

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Foam blown gas with a high specific-. solubility, or feed this gas along a stream of (low-expansion) foam coming from the foam generator.

When applying a high foam (about 1000) for several tens. meters (for example, when fire fighting) eliminates the need to use foam pipes. Since the hydraulic resistance of the foam in these pipelines is very large, the energy consumption for supplying the solution d of air to form the initial foam is also large. The proposed method eliminates the need to use such foam pipes and, consequently, leads to a reduction in energy consumption and ease of operation.

An increase in the multiplicity of foam several times as compared with the initial foam increases the efficiency of its foam .1

Compiled by T. Kruglov Editor A. Dolinich Tehred M. Morgantal

Order 5486/11

Circulation 547

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab., A / 5

changes while reducing the consumption of foaming components. )

Invention Formula

Claims (2)

1. A method of producing a foam of adjustable multiplicity, comprising mixing the foaming solution with a gas, characterized in that in order to increase the range of regulation of the multiplicity of the foam and reduce energy consumption, the foam is contacted with a foreign gas that differs in partial pressure and solubility from the gas contained in the foam bubbles. 2. A method of adjustable multiplicity according to claim 1, characterized in that the foam is sequentially contacted with several foreign gases in order to increase or decrease their solubility.  / J V2 Voij FIG. 2 Proofreader I. Muska Subscription