Ultrasonic demulsification mechanism
Ultrasonic waves are elastic mechanical waves propagating in the medium, with mechanical vibration, cavitation and heat. Theoretical derivation and visualization experiments prove that ultrasonic waves are broken
The intensity of milk must be below the cavitation threshold. Therefore, ultrasonic crude oil demulsification mainly uses the mechanical vibration and heat of ultrasonic waves.
Mechanism of action
1. The vibrational action causes the water "particles" to condense. When ultrasonic waves pass through a crude oil medium with suspended water "particles", causing suspended water "particles" and crude oil
2. Vibrate together. Since the water "particles" of different sizes have different relative vibration velocities, the water "particles" will collide and adhere to each other, so that the volume and mass of the particles are increased, and finally the sedimentation is separated.
3. The vibration effect can make the natural emulsifier such as paraffin, colloid and asphalt in the crude oil evenly dispersed, increase its solubility, reduce the mechanical strength of the oil-water interface film, and facilitate the separation and separation of the water phase. Thermal action reduces the strength of the oil-water interface film and the viscosity of the crude oil.
On the one hand: the boundary friction increases the temperature at the oil-water boundary, which is conducive to the rupture of the interface film.
On the other hand, the absorption of part of the sound energy by the crude oil can reduce the viscosity of the crude oil, which is beneficial to the gravity sedimentation separation of the oil-particles of the water.
Demulsification factors
1. There are many factors in wave breaking, such as sound intensity, ultrasonic frequency, radiation time, temperature, settling time, and viscosity of crude oil.
2. Strong and its distribution is one of the important factors affecting ultrasonic demulsification. The sound intensity must be controlled below the cavitation threshold. Due to the large differences in the properties of the crude oils, the optimal sound intensity required for demulsification is different.
3. The magnitude of the wave frequency affects only the distance traveled by the “particles” to the antinode or node motion in a quantitative range, and the effect of the demulsification effect on a quantitative level is not obvious. Kotyusov theoretically derives the influence of frequency on the "particle" condensation, and derives that the optimal frequency of the particles to produce agglomeration under the action of sound waves is about 21 ~ 25 kHz.
4. Emulsification and demulsification are actually a dynamic balancing process. Demulsification can be achieved by selecting the appropriate treatment time, but if the ultrasonic treatment time is too long, it is possible to emulsify the separated oil-water phase to form a more stable emulsion. Therefore, the sound wave irradiation time is not as long as possible.
The effect of crude oil demulsification and dehydration is obvious. The mass fraction of water after demulsification of crude oil decreases with the increase of temperature, but the decrease with the increase of temperature is smaller and smaller.
to sum up
Compared with other methods, ultrasonic can reduce the temperature of demulsification and dehydration, thereby reducing energy consumption, and at the same time eliminating complex high-voltage electric dehydration equipment. Therefore, the use of ultrasonic demulsification dehydration can reduce costs and improve economic efficiency. Ultrasound can also greatly reduce the amount of Demulsifier. The fluidity of the crude oil after ultrasonic treatment is greatly increased, and the viscosity does not recover after standing for a long time. However, there are still many problems to be solved, which is also the direction of future research and development.
1. The study of milk mechanism needs further study and theoretical analysis is difficult.
2. Conditional control is difficult. Different crude oils require different reaction conditions due to their different physicochemical properties.
3 is not high. Many applications are only done in the laboratory and there is no large-scale application to industrial production.
4. Suitable for industrialized ultrasonic demulsification equipment.