Study On The Anti-scaling Effect Of Alternating Electromagnetic Field On Circulating Cooling Water

Industrial circulating cooling water is mostly hard water,which will cause scale problems during use.Although the electromagnetic field technology in the physical anti-scale technology is widely used in circulating cooling water anti-scale,the antiscale mechanism of electromagnetic field to hard water has not been fully grasped so far.The main purposes of this paper are as follows: 1.To explore the relationship between high-voltage alternating electromagnetic field and water quality in the scale inhibition effect;2.To compare the scale inhibition effect of radio frequency electromagnetic field and high-voltage alternating electromagnetic field.Trying to explore the law of alternating electromagnetic field scaling under different water quality.The self-made "industrial circulating cooling water test bench" and "electromagnetic field anti-scaling processor" were used to carry out the electromagnetic field anti-scaling treatment experiment.Four kinds of experimental water were prepared.The calcium ion concentration in all experiments was 12mmol/L,and the magnesium ion concentration was 0mmol/L,2mmol/L,4mmol/L,6mmol/L.The circulating water is treated with an alternating electromagnetic field with a frequency of 50 Hz and a radio frequency electromagnetic field with a frequency of13.56 MHz.The voltage parameters of the alternating electromagnetic field are: 4k V,5k V and 6k V,the power of the radio frequency electromagnetic field is 200 watts.Each experiment runs for 12 hours,during which the circulating cooling water quality indicators are collected and tested every 2 hours.The fouling resistance and scale inhibition rate are collected and calculated by the computer in real time,and the sampling frequency is 6 times per minute.After the experimental operation,samples of the adherent scale attached to the inner wall of the copper tube of the heat exchanger and the non-adherent scale in the water collecting tank were collected.The samples were dried and analyzed by X-ray diffraction(XRD)and scanning electron microscope(SEM).The experimental results show that: First of all,water quality is an important factor that affects the scale inhibition effect of the electromagnetic field.Under different water quality conditions,the anti-scaling effect of the same electromagnetic field is significantly different.For example,in the alternating electromagnetic field experiment when the voltage is 4k V,the scale inhibition rate is 48.89% and-62.93% when the magnesium ion concentration is 2mmol/L and 4mmol/L,respectively.And the effect is completely opposite.Secondly,the anti-scaling effect of alternating electromagnetic field and radio frequency electromagnetic field has a non-linear relationship with the concentration of magnesium ions in the water.In an alternating electromagnetic field experiment with the same voltage,there is no obvious linear relationship between the the scale inhibition rate of average fouling resistance and the concentration of magnesium ions.In the radio frequency electromagnetic field experiment,when the frequency and power are both fixed,the scale inhibition rate of average fouling resistance does not increase with the increase of magnesium ion concentration.Both electromagnetic field experiments can achieve better scale inhibition effects only under specific experimental conditions.Finally,the effect of alternating electromagnetic fields is stronger than that of radio frequency electromagnetic fields.The best scale inhibition conditions of the alternating electromagnetic field are the 4k V of No.4experiment and the magnesium ion concentration is 6mmol/L,the scale inhibition rate average of fouling resistance is 59.11%.The best scale inhibition condition of the radio frequency electric field is that when the magnesium ion concentration is 6mmol/L,the scale inhibition rate of average fouling resistance is 9.53%.In this experiment,the antiscaling effect of the alternating electromagnetic field is better than that of the radio frequency electromagnetic field.Alternating electric field and radio frequency electric field also have a significant impact on the morphology of scale crystals.Compared with the control group without electromagnetic field treatment,rod-shaped crystals with aragonite structure appeared in the alternating electromagnetic field experiment.This kind of rod-shaped structure with two blunt ends appeared in the experimental group with better scale inhibition effect.After being treated by radio frequency electromagnetic field,the crystal particles of the scale sample showed two conditions,either the particles were fine and gathered together into a huge block structure,or the crystal particles were enlarged and presented irregularly shaped blocks,with almost no needles and rod-like crystals.