CC BY
61
УДК 662.691.4
application of ultrasound for the destruction of resin-paraffin deposits in pipeline transport of oil
HERBERT HOFSTATTER, Univ.-Prof. Dipl.-Ing. Dr.mont.,
Montan Universitat Leoben (Austria, A-8700 Leoben, Franz-Josef-Strasse 18)
MIKHAIL PAVLOV, BORIS MASTOBAEV, Univ.-Prof. Dipl.-Ing.
Ufa State Petroleum Technological University
(1, Kosmonavtov str., Ufa, 450062, Russian Federation) E-mail: [email protected]
The problem of the deposits of resin-paraffin substances on the walls of pipes is known from the beginning of industrial oil extraction and transportation. But today the unique solution of this problem is not found. Using the experience of domestic and foreign researchers (Montan Universitat Leoben) in the field of destruction of ARPD in the bottom hole zone and tubing in this work the possibility of application of ULTRASONic for the destruction of the SPO in the pipeline.
Keywords: deposits of resin-paraffin substances, pipes, ultrasonic.
process description
In a process termed cavitation, micron-size bubbles form and grow due to alternating positive and negative pressure waves in a solution. The bubbles subjected to these alternating pressure waves continue to grow until they reach resonant size. Just prior to the bubble implosion (Fig. 1), there is a tremendous amount of energy stored inside the bubble itself.
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Formation of a bubble at the surface under a layer
Fig. 1. Illustration of an imploding cavity in a liquid irradiated with ultrasound
Temperature inside a cavitating bubble can be extremely high, with pressures up to 500 atm. The implosion event, when it occurs near a hard surface, changes the bubble into a jet about one-tenth the bubble size, which travels at speeds up to 400 km/hr toward the hard surface. With the combination of pressure, temperature, and velocity, the jet frees contaminants from their bonds with the substrate. Because of the inherently small size of the jet and the relatively large energy, ultrasonic cleaning has the ability to reach into small crevices and remove entrapped soils very effectively (Fig. 2).
Separation piece of film from the surface at pulsation bubble Fig. 2. Process cavitation Equipment
The basic components of an ultrasonic cleaning system include a bank of ultrasonic transducers mounted to a radiating diaphragm, an electrical generator, and a pipe filled with oil. A key component is the transducer that generates the high-frequency mechanical energy. There are two types of ultrasonic transducers
Fig. 3. Piezoelectric transducers on a radiating diaphragm
транспорт и хранение нефтепродуктов и углеводородного сырья № 3 2014
used in the industry, piezoelectric and magnetostrictive. Both have the same functional objective, but the two types have dramatically different performance characteristics.
Piezoelectric transducers are made up of several components. The ceramic (usually lead zirconate) crystal is sandwiched between two strips of tin. When voltage is applied across the strips it creates a displacement in the crystal, known as the piezoelectric effect. When these transducers are mounted to a diaphragm (Fig. 3) on the walls or bottom of a tank, the displacement in the crystal causes a movement of the diaphragm, which in turn causes a pressure wave to be transmitted through the aqueous solution in the tank.
Because the mass of the crystal is not well matched to the mass of the stainless steel diaphragm, an intermediate aluminum block is used to improve impedance matching for more efficient transmission of vibratory energy to the diaphragm. The assembly is inexpensive to manufacture due to low material and labor costs. This low cost makes piezoelectric technology desirable for ultrasonic cleaning. For industrial cleaning, however, piezoelectric transducers have several shortcomings.
The most common problem is that the performance of a piezoelectric unit deteriorates over time. This can occur for several reasons. The crystal tends to depolarize itself over time and with use, which causes a substantial reduction in the strain characteristics of the crystal. As the crystal itself expands less, it cannot displace the diaphragm as much. Less vibratory energy is produced, and a decrease in cavitation is noticed in the tank. Additionally,
piezoelectric transducers are often mounted to the tank with an epoxy adhesive (Fig. 4), which is subject to fatigue at the high frequencies and high heat generated by the transducer and solution.
The epoxy bond eventually loosens, rendering the transducer useless. The capacitance of the crystal also changes over time and with use, affecting the resonant frequency and causing the generator to be out of tune with the crystal resonant circuit.
Experimental installation
Fig. 5 represents the photo of the experimental setup. One of the main purposes of experimentation is a clear show of that with the help of ultrasonic you can clean surface. In addition it is very important to set the parameters of ultrasound, in which perished cleaning for each on-were acquired in different settings.
For this experiment uses the open cube (3.5 x 4.5x x 4.5) cm from plexiglas. To the bottom of the cube attached piezoelement.
To commit the changes in the sample uses a highspeed camera (speed shooting up to 700 thousand frames per second). To ensure the necessary permissions on camera mounted microscope.
Lamp provides adequate illumination of the sample.
The impact on the sample will be provided via the piezoelement with the help ultrasonic generator waves and amplifier.
To find the resonant frequency of the system applies oscylograph (Fig. 6).
For the experiment was selected frequency 70-75 kHz, since when it has the highest resonance. Then
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Fig. 8. Muddy water
began the impact on the sample. His time was determined by the number of cycles for example, if the frequency 75 kHz we had the impact in one second, then installed 75 thousand cycles etc. Within the framework of this experiment impacts more than thirty seconds were not conducted. This is largely due to the fact that at a high resolution camera is its ability to record video files declined to 0.7 seconds. And because of cavitation bubbles are small (50-500 nm), to consider them only in case of significant increase.
Samples for the experiment were provided with the existing pipeline MN Tuimazy-Ufa -3197 km, pumping station «Cherkasy». The experiment was exactly
Fig. 9. Form of plate before, during and after the experiment
the same as described above. Resonant frequency was 75 kHz, amplitude 10V, one impact is not more than 10 seconds (Fig. 7).
After 3-5 seconds of exposure, the water was muddy and focus the camera became impossible (Fig 8).
The effect was realized cycles for five seconds. After one impact water in rabe was changed. Just had six cycles or thirty seconds. The photo shows the results in the form of plate before, during and after the experiment (Fig. 9).
The results suggest the possibility of application of ultrasonic waves for purification of paraffin from surfaces.
System overview
It is planned to use the ring resonator, mounted di-
транспорт и хранение нефтепродуктов и углеводородного сырья № 3 2014
Main Cable
!
Ultrasonic generator
Effective range
min=100m
max=?
Resonator
Wax precipitation
Fig. 10. Principal scheme
rectly on the pipeline. For effective influence on paraffins, must be installed several stations ultrasound.
Their number depends on the effective zone of influence of one station. Electricity supply is carried out through the main cable laid along the pipeline (fig.10).
Conclusion
Ultrasound can be effective in combating deposits. But for its correct and rational use need to solve a number of tasks, such as:
-adapt theultrasonic equipment for pipelines;
-to find the optimal frequency for specific oils;
-to find the real maximum effective ranges.
REFERENCES
1. V. Bjerknes. Fields of force. 1906.
2. R. Mettin and A. A. Doinikov: Appl. Acoust. 2009.
3. X. Xi et al.: Ultrasonics. 2011.
4. P.E. Frommhold, R. Mettin, F.L. Holsteyns, A. Lippert: Surface cleaning by soft acoustic cavitation bubbles. 2012.
ПРИМЕНЕНИЕ УЛЬТРАЗВУКА ДЛЯ РАЗРУШЕНИЯ АСФАЛЬТОСМОЛОПАРАФИНОВЫХ ОТЛОЖЕНИЙ В ТРУБОПРОВОДЕ ПРИ ТРАНСПОРТИРОВКЕ НЕФТИ
Хофштаттер Герберт, профессор,
Montan Universitat Leoben (A-8700 Leoben, Franz-Josef-Strasse 18) Павлов Михаил, Мастобаев Борис, профессор
Уфимский государственный нефтяной технический университет
(450062, Россия, Республика Башкортостан, г. Уфа, ул. Космонавтов, 1)
E-mail: [email protected]
Проблема асфальтосмолопарафиновых отложений (АСПО) на стенках труб известна с начала промышленной добычи и транспортировки нефти. Но сегодня единственное решение этой проблемы не найдено. Используя опыт отечественных и зарубежных исследователей (Montan Universitat Leoben) в области разрушения АСПО в призабойной зоне и трубопроводе, в этой работе рассмотрена возможность применения ультразвуковых волн. Ультразвук может быть эффективным в борьбе с отложениями. Для его правильного и рационального использования необходимо решить ряд задач, таких как:
-адаптация ультразвукового оборудования для трубопроводов;
-нахождение оптимальной частоты для конкретной нефти;
-нахождение реальных максимально эффективных диапазонов.
СПИСОК ЛИТЕРАТУРЫ
1. V. Bjerknes. Fields of force. 1906.
2. R. Mettin and A.A. Doinikov: Appl. Acoust. 2009.
3. X. Xi et al. Ultrasonics. 2011.
4. P.E. Frommhold, R. Mettin, F.L. Holsteyns, A. Lippert: Surface cleaning by soft acoustic cavitation bubbles. 2012.
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