Performance And Mechanism Of Scale Inhibitors And Study On It At High Temperature And High Pressure

The circulating cooling water system is an inevitable part of most industrial production.It requires a large number of water to achieve the production.To save the water resources,producers used it repeatly.With the ion concentration in the solution improve,the tendency of scaling in the water increases.The formation of calcium carbornate will cause the technical problems such as the reduction of heat transfer efficiency,pipe blockage and equipment damage,so it was regarded as one of the most chanllenging problem in cooling water system.To resolve this problem,use scale inhibitors was the best solution.The performance of different scale inhibitors including phosphine hydrolysis polymaleic anhydride?PHPMA?,acrylic acid and maleic anhydride copolymer?AA/MA?and hydrolysis polymaleic anhydride?HPMA?was evacuated by static calcium carbonate deposition method.X-ray diffraction?XRD?,scanning electron microscopy?SEM?and FT-IR were used to analyze the CaCO₃ scale.The results show that the scale inhibition increases with the added amount of inhibitor,but all the three scale inhibitors exhibit“threshold effect”at high dosage;The order of scale inhibition efficiency was PHPMA>AA/MA>HPMA,and the efficiency of PHPMA can reach 95.9%after 10h at 80?;The addition of scale inhibitor can significantly affect the morphology of calcium carbonate scale,with the main crystal form changing from calcite to vaterite.For the same scale inhibitor,the better performance of scale inhibitior is,the more vaterite can be founded in their scale.The mechanism of scale inhibition was further explained based on the results.Use self-designed reactor to evaluate the scale inhibitors performance at high temperature and high pressure of the coal gasfication ash water system.The research screen out the PAPEMP and BHMTPMPA from all the scale inhibitors as the best scale inhibitors,the polycarboxylic acid s cale inhibitors lose its effect at this condition.It has been found that when the mixing ratio of PAA:BHMTPMPA=1:3,the dosage of scale inhibitor was200mg/L,other condition was 180?,n(Ca²⁺)=240mg/L,the scale inhibition can reach 67%.To solve the bonding problem of coal ash and CaCO₃,it has been found that DISPER 303T has good dispersion property.After mixing with LEVIN 199H,it change the crystal form of calcium carbornate scale at some certain extent.