HOW IS ULTRASONIC TECHNOLOGY RANKED AMONG OTHER METHODS OF CONTROLLING SCALE IN INDUSTRY?
Industrial methods of controlling scale may be divided into three main groups:
- Water softening or to put it differently, chemical water treatment (CWT) is chemical removal of all dissolved salts from water. Desalination is an expensive and complicated, but in most cases necessary, process. Ideally, water softening radically solves the problem of scale formation, however in practice this is far from being always so. Qualified chemical engineers and uninterrupted supply of reagents are not present everywhere.
- Adding of special reagents into heated water, which prevent hardness, salts to precipitate. This method is used rather rarely, because it requires consumables, but does not solve the scale formation problem once and forever.
- Physical methods for protection against scale.. They are suitable as they require no consumables and have no elements in contact with water. Physical methods include magnetic and electromagnetic water treatment. Magnetic filters with permanent magnets, electromagnetic devices, electrolytic plants etc. are applied. All these units provide some antiscale effect, but are highly dependent on water flow rate and chemical composition. In some places they are effective, but in others they are not at all. Electromagnetic units are usually applied in everyday life or where water flow rates are low. Meanwhile, you should keep in mind that all physical methods just reduce the rate of scale formation, but do not eliminate it forever.
- • Ultrasonic protection against scale is one of physical methods of antiscale protection. Ultrasound works in any water; it is not sensitive to changes in water flow and prevents any solid deposits, regardless of their origin.
What is the secret of ultrasound efficiency? It is in the fact that ultrasound causes micromechanical effect on both metal of tubes or plates and water. Flexural modes of about 5 mkm amplitude occur in metal, which do not allow salt crystals to adhere to the surface. In water, ultrasonic vibrations are permanently destroying all kinds of crystals formed during heating, and crystallization proceeds in the water rather than on the metal. For ultrasound, it doesn’t matter what flow rate, salts, water, temperature, metal etc. are in place. It simply does its job, and does it well!
HOW COULD WE CALCULATE ECONOMIC BENEFITS FROM APPLICATION OF ANTISCALE ACOUSTIC DEVICES «ACOUSTIC-T»?
Economic benefits from application of «Acoustic-T» device is composed of two components:
- Cost savings for chemical and mechanical cleaning of heat exchangers.
- Cost savings for fuel, water and electric power, because thermal conductivity of scale is 50 times lower than that of metal, and clean heat exchanging equipment operates with no losses.
Anti-scale devices «Acoustic-T» 4-fold, 5-fold and more decrease the scale formation rate (this depends on local water and other conditions of particular equipment), i.e. 4...5-fold decrease expenses for cleaning. Cost price of one boiler or heat exchanger equipping with «Acoustic-T» device is approximately the same as the cost of their single chemical cleaning. Thus, «Acoustic-T» pays off very quickly.
As for permanent operating costs, as referred to in literature, a 1 mm thick scale layer in shell-and-tube heat exchangers causes 3-fold increase of heat carrier flow rate with all ensuring losses of power for heat carrier pumping.
As for plate heat exchangers, those equipped with antiscale devices of «Acoustic-T» series,i.e. clean ones, demonstrate heat transfer factor of 10 – 27 % higher than in heat exchangers of the same type, according to specification and connected load of control heat exchangers. Specific heat carrier flow rate is by 10-30 % lower than in control units, not equipped with antiscale devices. Returned water temperature is, on average, by 5 °С lower. These data were obtained in experiments, by processing data from heat meters of three Central Heat Supply Station of one of Moscow City districts, where we have shown that heat supply stations not equipped with antiscale devices provided excessive consumption of heat carrier of 2.5 to 8 tons per every Gcal of heat produced in domestic hot water system. Heat and power losses are proportional to this excessive consumption.
ARE ANTISCALE DEVICES APPLIED IN ELECTRIC POWER INDUSTRY?
On many electric power stations the problem of scale formation on raw water heaters, the so-called RWH, is in place. Our devices are operated at such heaters at Yaroslavskaya TPP-3 (Russian Federation), Bezymyannaya TPP in Samara (Russian Federation), and at many other electric power stations.
To observe examples of «Acoustic-T» devices installed on heat exchange equipment,
WE HAVE ALREADY HEARD ABOUT THIS ULTRASOUND THIRTY YEARS AGO. IF IT IS SO GOOD, WHY IS IT NOT APPLIED IN EVERY HEATING STATION AND EVERY BOILER?
The principle of ultrasonic vibrations to prevent scale formation was suggested quite a long time ago. In 1970s, Andreev Acoustic Institute performed studies that indicated the range of 18-25kHz for ultrasonic frequency to be the most effective for preventing scale formation. At the same time, the first Soviet ultrasonic device "Acoustic-1" was designed and put to mass production. This device was rather good due to power of ultrasonic signal, but too large, heavy and extremely impractical. Moreover, in places where we have saw "Acoustic-1" devices, they all were incorrectly installed.
On the decline of the Soviet Power and in 1990's, some more kinds of ultrasonic devices by different manufacturers appeared in the market. They were of suitable dimensions, but exhibited very low ultrasonic signal. The problem was as follows - by type of excitation of vibration of required frequency, ultrasonic devices can be classified into two types:
- In the first type of devices, vibrations are excited by a video pulse, and the transducer's structure is designed as a resonance system with required main resonance frequency. In this case, irradiated signal power is "smeared" by the spectrum, and its main part falls on frequency ranges useless for scale prevention. We cannot say that devices of the first type operating on a video pulse were absolutely useless, they had to be used with regard to their specific features. However, heat power engineers were not obliged to understand those details, and many customers, who had purchased ultrasonic devices of the older generation, were disappointed.
- In devices of the new generation, to which «Acoustic-T» devices belong, this design of transducer is added by induced vibrations, excited by a radio pulse. The main advantage of this is that it allows us to focus the entire power of generated signal only in the frequency range suitable for scale prevention. The main part of signal power is concentrated in the required frequency range, where the level of radiated power is 30 times higher than signal power levels radiated by devices of the first type. Now antiscale capabilities of ultrasound are used in heat power engineering to the full extent.
If you still have any questions — we will be glad to answer them.