Principles and types of foam generator technology

What is foam generator?

Foaming machine, also known as foam generator, is a kind of foam equipment that makes foaming agent reach a certain concentration of aqueous solution. The foaming agent itself cannot automatically become a foam, it must pass the mechanical action of the foaming machine to become foam.

What is the principle of the foam generator?

Regardless of the foam generator, the basic principle of foaming is to introduce air into the foaming agent solution. The various types of changes are different in the way of introducing gas, so the effect is also different.

There are two necessary factors for the formation of foam, one is foaming agent solution, and the other is air, both of which are indispensable. Without the blowing agent solution, the liquid film surrounding the gas would not form and there would be no bubbles. And without gas, foaming agent solution alone cannot form bubbles.

In the bubble formation system, the blowing agent solution is the dispersion medium, the gas is the dispersed phase, and the gas is dispersed in the liquid to form bubbles, and then numerous bubbles form the foam. In addition to the important factor of blowing agent performance, the introduction of gas into the blowing agent solution is another important factor. The principle of the foam generator is to introduce gas into the liquid, i, the foam generator uses a certain method to introduce the gas into the liquid. Different foaming machines have different methods of introducing gas. In general, there are several ways to introduce gas into the foaming machine:

(1) Slowly rotating blades introduce gas

This is a method of directly introducing gas into mortar (or concrete slurry) mixed with cement foaming agent. When the mixer blade pushes the slurry, air enters the slurry with the mixer blades. Ntxiv rau, a large amount of air is wrapped into the slurry when the slurry is turned over, and a part of the air is brought into the slurry by the cement and aggregate. The sum of the three is the total amount of air entering the slurry. Among them, the air brought into the slurry by the stirring blade and the air wrapped by the blade turning the slurry occupy the main body.

After the air enters the slurry, the liquid containing the foaming agent surfactant surrounds the air, forming a double-electron layer liquid film at the interface between the air and the liquid, and finally forms the bubbles in the slurry in the form of air-in-liquid.

Due to the slow rotation speed of the blades and less gas introduced in this way, the amount of bubbles generated is small, the foaming effect is not good, and the efficiency is low.

(2) High-speed rotating blades introduce gas

This is a way of introducing gas into the blowing agent solution by relying on high-speed rotating blades. The introduction of the gas mainly depends on the force of the rotating blades. The blades of this type generally require high-speed rotation, the speed should be> 700 rpm, feem ntau nruab nrab 700 thiab 1400 r/min, and the peripheral speed of the impeller end should be> 20 m/s in order to obtain satisfactory results. A certain high speed can expose the impeller to the liquid, contact with air, and introduce air. If the speed is too low, lub impeller yuav tsis raug tso rau hauv kua, thiab qhov ntau ntawm cua tawm yuav tsawg heev. Lub ceev tsim nyog yuav tsum qis dua thaum lub impeller raug kua thaum tig.

Lub ntsiab cai tseem ceeb ntawm impeller bleed air yog raws li hauv qab no:

Thaum lub impeller tig ceev siab, nws tsav cov kua tshuaj cement foaming hauv lub tog raj mis ua npuas kom tig, ua ib qho kev ncig thiab tsim ib qho vortex loj. a, cov pa roj-kua ob-theem uas nyob ntawm qhov sib txuas roj-kua ntawm saum toj ntawm cov kua tshuaj foaming yuav nqis nrog nws mus rau hauv qab ntawm vortex hauv ib qho kev tig ceev, ua ib qho chaw ntws turbulent ntawm 2.5-5 cm ntawm ntug impeller. Nyob hauv thaj chaw no, the gas-liquid two-phase particles are subjected to the strong shear and impact of the impeller, and are dispersed into fine dispersions, which quickly realizes the gas-liquid mixing, makes the gas uniformly dispersed in the liquid, and realizes the gas Introduce. Its introduction efficiency is related to various technical factors such as the speed, the diameter of the impeller, the distance between the impeller and the foaming tube, and the shape of the impeller blades. It is not determined by a single speed. High-speed impellers have air-entraining effects, but the efficiency, u, and energy consumption are different.

(3) Use of pressure to introduce gas.

This is currently the most commonly used advanced air-entrained foaming method at home and abroad. It is also a more scientific air-entraining method. It is the core of foam concrete high-pressure and medium-pressure foam generator technology.

The two methods mentioned above are slow and uneven, and the bubble diameter is large, especially the bubble diameter cannot be controlled. It is completely dependent on the randomness of the foaming machine, and cannot guarantee the small bubble diameter and uniform foam. The most critical technical indicators. Nyob rau tib lub sijhawm, the amount of foaming is difficult to control.

In order to effectively solve the above problems, the pressure-entrained foaming method came into being. Regardless of foaming volume, foaming speed, or foam diameter and foam uniformity, etc., they have stepped on a new level and have made great technological progress. Its main principle is to use various equipment that can generate air pressure to press air into the liquid phase to achieve uniform mixing of the two phases. Under normal pressure, it is difficult for air to enter the liquid, but under certain pressure, it becomes easier. This air pressure not only presses the gas into the liquid, but also presses the liquid into the gas. Qhov tseeb, it simultaneously applies pressure. In this way, the mixing of the two phases will be fast, efficient, uniform, and have fine bubbles, which meets the ideal technical requirements for foam.

There are two main types of pressure equipment used in our country, one is an air compressor and the other is a blower. The air compressor produces high pressure, and the blower produces medium low pressure. Yog li ntawd, the foaming effect of the air compressor is better, and the foaming effect of the blower is slightly worse. Foaming with an air compressor is called a high-pressure foaming machine, and foaming with a blower is called a medium and low pressure foam generator. The foaming quality of the air compressor mainly controls its pressure and displacement, while the foaming of the blower mainly controls its wind pressure and air volume.

Due to the good foaming effect of air compression mechanism, most foaming machines in our country use air compressors. Blower foaming also has many applications in my country, but compared to high-pressure foaming, this foaming method is still rare. The foam produced by high-pressure air foaming has a low water-sucking rate, the bubble diameter is small, dense and uniform, and the quality is high. Cov foam uas tsim los ntawm blast foaming muaj qhov dav me ntsis loj dua, thiab qhov zoo tag nrho tsis zoo li foaming siab siab.

(4) Pressure jet siab ua rau muaj pa

Qhov no yog ib txoj kev foaming uas tau sim xyoo tsis ntev los no tab sis tsis tau siv dav. Lub ntsiab cai tseem ceeb yog siv lub zog dispersion muaj zog uas jet tsim los kom tau kev sib cuag loj ntawm qhov chaw ntawm gas phase thiab liquid phase tam sim ntawd, kom ob qho sib xyaw ua ke, thiab cov kua raug kaw ua foam. Qhov no txoj kev no tsis muaj qhov zoo dua li foaming cua siab siab, thiab nws tseem xav tau kev tshawb fawb thiab txhim kho ntxiv.

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