Research On The Oxidative Decomposition Properties Of SO₄^2- Of Cationic Exchanges Resin Of Power Plant

In recent years, many power plants have emerged the phenomenon that when they putcondensate polishing system into operation, the sulfate in the water vapor system will increase.Many studies found that that the root cause of this phenomenon is the strong acid cationexchange resin leak into the system, or sulfonic acid groups on the resin organic chain off,which cause the increasing of sulfate content. In allusion to this problem, dynamic circulationmethod and static immersion method is used in the dissolution experiments of severalimports of strong acid cation exchange resin under the conditions of oxidants. And hydrogenperoxide and chlorine has been selected as the oxidant. We choose of hydrogen peroxide todeal with the ion exchange resin in the tank system of PWR nuclear power plant primarycircuit and Chlorine to reduce the affect caused by the hypochlorite which is added into theraw water sterilization processing.The result shows that after the dynamic cycle experiments performing for 120h under theoxidizing environment, the amount of sulfate and TOC in the four kinds of Strong acid typecationic exchange resin increases as the time goes, but the speed of which falls down. Theexperiment also shows that the dissolving amount and speed of macroporous resin SP112H issmall that the others. Some resins’dissolving amount reaches over 60mgSO₄²-/L wet resin.The amount of sulfate is 650C > 1500H > S200 > SP112H.The research also finds that there is proportionate relationship between sulfate and TOC.The ratio between TOC and sulfate in the blank experiment shows a rising trend which is notso steady, and the dissolving amount of sulfate is far less than TOC. As the time goes, dbecomes larger and larger, which shows the decreasing of dissolving speed of sulfate is largerthan TOC. However, in H₂O₂, d becomes steady and gets smaller as the concentration ofH₂O₂ increases. The result shows that H₂O₂’s affect on desulfonation of macroporous resin islarger than the organic carbon chain..The reason of which is that in the organic linker of resin,the activity of alpha carbon is larger than the others. As a result, the oxidizer will performdesulfonation with it first.Through dynamic cycle experiments and static immersion test of different species andconcentration of oxidant, and finnd that the type of oxidants added can result different effectsto the dissolution of sulfate and TOC of resin. The amount of dissolving sulfate of resin increased with the intensity of oxidants, which shows that the dissolving amount and rateunder the condition of chlorine is larger than that under the condition of hydrogen peroxide.This is also related to the activity ofαcarbon in the organic chain of strong acid cation resin.Oxidants will directly affect the stability ofαcarbon, and it is more obvious when the oxidantis stronger. And with the oxidant concentration increased, the dissolution of sulfate and TOC’svolume and rate will increase.The static immersion test results under different temperatures show that the impact oftemperature to strong acid cation resin is larger than oxidant in the environment of lowconcentration oxidant. This shows that the three dissolution curve of blank, hydrogenperoxide and chlorine in each temperature is ray-like, and with temperature increasing theangle of the three curves are getting smaller.By comparing the data of the dissolution of macroporous resin and gel-type resin, wefound that the leaching of dissolving rate of sulfate and TOC of macroporous resin are lessthan the gel-type resin. The reticular formation of the macroporous resin is more relaxed thanthe gel type resin, and fewer low molecular weight organic short-chain can be residual, and ithas a strong resistance to surface contamination. In addition, the degree of crosslinking of theresin is resin leachables important factor, but this process is very complex.Synthesizing the data of sulfate stripping by the four kinds of strong acid cation resin inthe dynamic loop experiments and static immersion test, we found that the strength ofoxidation resistance of the four resin as follows:650C > 1500H > S200 > SP112HIn summary, oxidants can cause the dissolution behavior of sulfate and TOC of strongacid cation resin increase, and their extraction will increase the burden in the ion exchangesystem. It can pollute anion exchange resin, and cause anion leakage in the system, thenbecomes a great impact to the vapor quality. Therefore, it is recommended that it’s necessaryto carry on the monitoring to the oxidizing substances in the system in each power station,and select a resin of high anti-oxidative stability, anti-penetration impact properties as the ionexchanger for ion exchange system.