Study On Scale Inhibition And Scale Removal In Wet Oxidative Regeneration Activated Carbon System

In this paper,for the actual production of a plant activated carbon wet oxidation regeneration system,there are serious heat exchanger scaling and descaling problems such as poor performance,scaling and descaling experiments.The main conclusions are as follows:Pretreatment of carbon sludge with sodium carbonate and sodium hydroxide as scale inhibitors can significantly reduce the scale generation in activated carbon regeneration system.The optimal reaction parameters of scale inhibitor for pretreatment of carbon mud are:sodium carbonate 0.7g/L,sodium hydroxide 0.3g/L.After pretreatment,the total removal rate of carbonaceous mud reached 70.8%,the hard removal rate of calcium was 85.0%and the hard removal rate of magnesium was 80.6%.According to the actual field test,after the scale inhibition pretreatment,the generation rate of scale is reduced by 85%.Nitric acid has obvious descaling effect.According to the actual operating conditions in the field,the best parameter of nitric acid descaling is determined as concentration of 5%and temperature of 80℃,the reaction time is 8h.Under these conditions,the removal rate of scale reaches 40.6%.Potassium permanganate oxidation pretreatment+nitric acid descaling can obviously improve the removal rate of scale.The optimal reaction conditions of potassium permanganate oxidation pretreatment were:potassium permanganate concentration of 100mmoL/L,pH value of 4,reaction time of 4h;Fenton oxidation pretreatment+nitric acid descaling,can significantly improve the removal rate of scale,Fenton oxidation method pretreatment scale oxidation optimum conditions:Fe²⁺/H₂O₂ ratio of 1.25,H₂O₂ dosage 12mL/L,FeSO₄ dosage 15g/L,the reaction time 1.5h,pH 4;will Fen Dayton oxidation pretreatment+acid+sodium hydroxide/EDTA disodium combined descaling,cleaning efficiency was significantly improved.The optimized scheme of the combined treatment is as follows:the scale sample is soaked in 5%nitric acid for 8 hours at 80℃.,and then soaked in 5%sodium hydroxide/1.5%EDTA disodium for 8 hours,Removal rate can reach 90.2%.