R&D Of Multiple Chemicals Applicable To Water With Hardness And High Alkalinity

In most area of north China, the natural water has high concentration of hardness and alkalinity. So it has great scale tendency. If the water is used as circulation cooling water, it's very easy to scale in the exchanger equipments. However,it's hard to get good corrosion and scale inhibition if we treat this kind of water with common chemicals. In this test, some chemicals with good inhibition performance for CaCO₃, Ca₃(PO₄)₂ and Zn were screened out through scale inhibition test. Then a basic formula was made through corrosion inhibition test. At last, a multiple chemical formula with optimum ratio for water with high concentration of hardness and alkalinity named SB-1Multiple Water Stabilizer Agent was chosen through lab dynamic simulation evaluation. The lab dynamic simulation evaluation shows that the SB-1Multiple Water Stabilizer Agent has good scale and corrosion inhibition performance. The average tube corrosion rate, adherence rate and dirtiness resistance are all up to the "very good" standard of Lab Dynamic Simulation Evaluation Criteria of CNPC. The average test slab corrosion rate is 0.0034mm.a^-1 ; the average tube corrosion rate is 0.0073 mm.a^-1; the tube adherence rate is 5.72mcm; the tube dirtiness resistance is 0.71×10^-4m2.h.℃/Kcal. The evaluation result shows that this kind of chemical is applicable to the water with high concentration of hardness and alkalinity. The make-up water for circulation water system of PetroChina Jinxi Company is with high concentration of hardness and alkalinity. To test the practical performance of SB-1Multiple Water Stabilizer Agent, a practical application test was carried out in the No.9 circulation water plant of PetroChina Jinxi Company. After one year's operation, the SB-1Multiple Water Stabilizer Agent can alleviate the corrosion and scaling problem in the circulation water system. The exchanger data shows that the corrosion and scale inhibition performance is the best when the enrichment factor of SB-1Multiple Water Stabilizer Agent is 3.0. The tube adherence rates are all less than 30mcm every month, and the average tube corrosion rates are less than 0.100 mm.a-1 . All the data meet the "Good" and "Very good" standard of Field Monitoring Evaluation Criteria of CNPC. To apply this kind of chemical can improve the heat exchange efficiency and life cycle of equipments. So it has great economic benefit. The characteristic of this thesis is that the collaboration effect of individual chemical in the multiple chemical formulas. The corrosion and scale inhibition performance are the best when the enrichment factor of SB-1Multiple Water Stabilizer Agent is 3.0 (the Calcium and total alkalinity keeps at 1200mg.l-1).