Studying On The Coagulation Conditions In Water Treatment For TQNPC

The purpose of this paper is to obtain the optimizing coagulation conditions of water treatment for nuclear power stations via experiments. According the characteristics and variability of temperature of raw water from TQNPC, coagulants and coagulant aids are screened out. The optimal dosage and dosing conditions of coagulants and coagulant aids are also determined through the experiments. All of these aims are to optimize the effect of coagulation of raw water and provide truth for the running of clarifier tank in demineralized water production system of nuclear power plant.The following experiments are implemented:(1) Jar experiment: through jar experiment, coagulants and coagulant aids are screened out for the raw water treatment for TQNPC; the coagulation mechanisms of typical coagulant and coagulant aid were discussed in this paper,and the optimal coagulant and coagulant dosage of raw water for TQNPC was also Determined.(2) Pilot experiment: the parameters acquired from a serial jar experiments are applied to water pretreatment system of TQNPC to implement the industrial performance test. By contrasting the effect of Polyaluminium Chloride and Ferric trichloride, the effect of Ferric trichloride for low temperature and low turbidity water from TQNPC is examined roundly, and the dosage of Ferric trichloride for variable turbidity and temperature is determined further.The experimental results show that the optimal coagulant for low temperature and low turbidity water from TQNPC is Ferric trichloride, Polyaluminium Chloride is the next.The effect of coagulation will be good if the dosage of Ferric trichloride is between 0.03mg/L and 0.06mg/L. But 0.04mg/L is suggested because more Ferric trichloride can change the water color easily. The PAM and PDMDAAC are coagulant aids that can enhance the effect of coagulation, but both of them don't work for low temperature and low turbidity water and aren't encouraged to use. The coagulant aid PDMDAAC can be considered when necessary because it is a polymer and it is innoxious. The spot system running experiment shows that the water turbidity of filter output can be about 0.5NTU stably.