Study On Scale Inhibition Effect Of The Combination Of Micro-nano Bubbles And Scale Inhibitor

Pipe fouling has been one of the major safety issues facing circulating cooling systems.Various physical and chemical methods have always been used to control fouling,but all of them have certain defects,and there is a great need to develop new antiscalation technologies.Micro-nano bubble technology has become a research hotspot in the current environmental field because of its green color,low cost,high performance and easy operation,which has been largely reported in membrane filtration and solid surface cleaning,but a few studies related to the physicochemical characteristics and fouling resistance performance of micro-nano bubble（MNBs）in circulatory cooling systems have been reported,which limits the application of cyclic cooling systems based on green fouling inhibition technology of MNBs.It is well known that there are 2 important indicators,bubble size distribution and surface zeta potential,which determine the physicochemical properties and effects of MNBs,and the variation law of these 2 indicators is highly dependent on external conditions.The circulation cooling system has the characteristics of high salt content,strong alkalinity and large temperature difference in water,and the study of the effects of the environment of the complex working condition on the properties and effects of MNBs is an important theoretical basis for its application.The specific research contents and results are as follows:（1）To examine the physicochemical properties of MNBs,the main salt fraction（Ca Cl₂）,p H value,and temperature changes in the circulating cooling water were used as the main environmental factors,and the effects on the air micro-nano bubbles（Air-MNBs）size distribution and zeta potential,stability,and coalescence behaviors of Air-MNBs were investigated.The results showed that:the greater the pressure in the micro-nano bubble generator,the greater was the proportion of small particle size of the Air-MNBs produced,and the addition of Ca Cl₂ contributed to the shrinkage of the bubble particle size.With the increase of Ca Cl₂ concentration,p H value and temperature in the solution,the average particle size of Air-NMBs in the solution decreased gradually,but the coalescence between bubbles would cause the particle size to increase gradually with time;It was found to exist in solution for 5 days by real-time monitoring of the Air-MNBs particle size.（2）In order to investigate the Air-MNBs fouling performance,the fouling inhibition effect of Air-MNBs on Ca CO₃ was investigated under six factor changes,including operation pressure,inlet flow,temperature,Ca²⁺concentration,aeration time,and standing time,using Air-MNBs as a temporary fouling inhibitor and the fouling capacity was evaluated;And the Ca CO₃ crystals were characterized by laser particle size analyzer,X-ray diffraction（XRD）and scanning electron microscopy（SEM）.The results showed that:after passing through the Air-MNBs,the fouling amount was significantly reduced,and the Ca CO₃ crystal particle size enlarged more than 4～5 times compared with that of the blank sample;Ca CO₃ crystal morphological characterization revealed that the Air-MNBs destroyed the aggregation and order processes of the crystals,and the formation of regular crystals was altered or precipitated as irregular crystals.Further investigation found that Air-MNBs not only reduced the salt precipitation but also reduced the Ca²⁺content in the solution.（3）In order to examine the application performance of Air-MNBs within the cyclic cooling system by simulating the regenerated water as the replenished water for the cyclic cooling system,the application effect of Air-MNBs was investigated using a dynamic simulation unit for the cyclic cooling system,to evaluate the effect of Air-MNBs on the fouling of the cyclic cooling system under real working conditions,and to examine the effect of operation conditions of the unit（temperature,flow rate,and concentration rate）on the fouling inhibition effect of Air-MNBs.The results show that Air-MNBs can effectively suppress the crystal deposition on the pipe surface,and the fouling inhibition effect is more excellent than that of hydroxyethylene diphosphonic acid（HEDP）.In summary,Air-MNBs are effective in controlling the crystallization of calcium scales...