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Research on Aging Inhibiting Corrosion and Scaling Properties of Green Water Treatment Agents in the Plants’ Recycled Water

Author: WangGang
Tutor: YangDaoWu
School: Changsha University of Science and Technology
Course: Physical and chemical
Keywords: Green water treatment agents Cycling cooling water Inhibiting corrosion and scaling PASP PESA Quantum chemical calculation
CLC: TM621
Type: Master's thesis
Year: 2009
Downloads: 135
Quote: 1
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Abstract

The quality of cycling cooling water in power plants has an important role on the safety and economic operation, which is directly related to the effect of energy conservation and reduction in power plants. The low efficiency in using recycled water, corrosion and scaling in cooling water system are the main problems. The main metals of the circulating water system is carbon steel(A20)and copper(HSn701). In order to resolve those problems, there are some methods, such as scale static method, static hanging method, orthogonal method and Tafel polarization curve method. In addition, the inhibiting corrosion and scaling of PASP and Na2WO4 for HSn701 have been studied in high concentration ratio of circulating water. Then, through scale static method, static hanging method and limit carbonate method, Tafel polarization curve method, the inhibiting corrosion and scaling of green water treatment agents such as HEDP and so on for A20 has been studied in the [Ca2 +] = [HCO3-] = 250 mg / L of simulate recycled water. Finally, PASP and PESA on a quantum chemical study have been done.The results indicate that PASP and Na2WO4 complex for HSn701 have corrosion inhibition in high concentration ratio of circulating water when the total concentration of inhibitor is 80mg / L and Zinc salts acts as additives (2mg / L). The optimum composite formula is 40mg / L PASP and 40 mg / L Na2WO4. Both complexes for HSn701 significant synergistic inhibition have the same effects. Complex belongs to the negative mix-controlled corrosion and scale inhibitors.In the simulate recycled water,the order of their inhibition performance is PESA﹥HEDP﹥AA/AMPS when the concentrations of Ca2 + and HCO3- are 250 mg / L. The best prescription is HEDP 2.5mg / L, PESA1.5 mg / L, imidazoline 1.5 mg / L. The best pH value is between8.0 and 8.5. Mix-controlled corrosion and scale inhibitors is a kind of compound pharmacies which can inhibit the anode part. To achieve the effect of inhibition, it can make a complex interaction and synergy of both lattice distortions. This formulation of the A20 steel has a good effect on corrosion and scale inhibition. It can effectively prevent calcium carbonate deposition. It has a good effect on environmental protection, low-cost, safe system for circulating cooling water. The results of quantum chemical calculation show that PASP and PESA are flexible molecules ,it is suitable not only for calcium carbonate scale inhibition, but also for the sulphate scale inhibition. They are both broad-spectrum inhibitors. Imino group and carboxyl group are scale ones , and they are absorbed on the surface of the calcium carbonate crystal on the effect of electrostatic. Though inducing lattice distortion and scale, the introduction of organic molecules and carboxyl imino can be enhanced molecular scale inhibition performance. EHOMO of PESA and PASP is in great value. Thus they are easy to participate in the pro-nuclear reactions and form a coordination bond with the metal surface of an empty d orbital, which increases their corrosion properties. These actions are of the E-cathode corrosion inhibitor. It will strengthen the ability of pro-nuclear reactions if the imino and carboxyl are introduced into the molecules of the corrosion and scale inhibitor.It will strengthen the ability of pro-nuclear reactions if the imino and carboxyl are introduced into the molecules of the corrosion and scale inhibitor

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