再生水循环冷却系统中无机磷的迁移转化研究

发布时间：2018-05-06 05:22

本文选题：再生水 + 循环冷却水系统　；参考：《华北电力大学》2017年硕士论文

【摘要】：近年来,随着水资源问题的日益突出,再生水已成为电厂循环冷却水系统补给水的重要水源。再生水具有水质稳定、来源可靠且不需要长距离引水的特点,然而再生水复杂的水质条件导致循环冷却水系统将面临更加严峻的运行问题。再生水中的磷含量较高且存在形态多种多样,是影响循环冷却水系统结垢、腐蚀和微生物生长的重要因素之一。本课题以模拟再生水中的无机磷为研究对象,考察无机磷的迁移转化规律以及运行条件和水质条件对其的影响。研究借鉴河床底泥中无机磷的SMT连续提取法,建立了模拟系统内垢体中无机磷定量定性分析的M-SMT法。通过分别测定溶解态无机磷和垢体中无机磷的具体存在形态及含量,同时分析系统内的结垢和腐蚀情况,总结循环冷却水系统中无机磷的迁移转化规律及其对系统结垢、腐蚀的影响。研究结果表明,M-SMT连续提取法能够对模拟系统内垢体中的无机磷进行完全提取,回收率接近100%;不同形态无机磷可以得到完全分离。溶解态无机磷向垢体中的迁移主要受成垢离子积和相应难溶物溶度积的影响。运行条件中,温度是影响无机磷在液-固两相中迁移的主要因素,温度升高,难溶物溶度积降低,溶解态无机磷的迁移速率、迁移量及迁移率均明显上升。水质条件中,增加单一无机磷或硬度均使成垢离子积显著增加,因此,无机磷的迁移速率和迁移量增加,但受成垢阳离子浓度的影响,水中无机磷浓度增加后,其迁移率降低。磷酸盐沉积物是系统结垢的主要成分之一,系统结垢量与无机磷的迁移量在一定程度上呈正比。浓缩倍率由2提升到6,系统内无机磷迁移量增加了920 mg,同时系统内结垢量由2.85g增加到9.35g,结垢量上升明显。不同条件对颗粒态无机磷的影响不同,运行条件中,随着流速的增大,弱吸附态磷含量呈下降趋势,而铝结合态磷含量逐渐上升;温度升高促进铝结合态磷向铁结合态磷和钙结合态磷的转化;提高浓缩倍率对4种形态无机磷的影响相同,其含量均有所上升,但占总颗粒态无机磷的比例无明显变化。水质条件中,随着无机磷浓度的增加,无机磷迁移至固相之中的量增加,且以形成弱吸附态磷和钙结合态磷为主;而系统中总硬度的增加,则有利于钙结合态磷的形成。系统内挂片的腐蚀率受系统结垢量、弱吸附态磷和铝结合态磷含量的综合影响。
[Abstract]:In recent years, with the increasingly prominent problem of water resources, reclaimed water has become an important source of recharge water for the circulating cooling water system in power plants. The reclaimed water has the characteristics of stable water quality, reliable source and no need for long distance water diversion. However, the complex water quality conditions of the reclaimed water will lead to more severe operational problems for the circulating cooling water system. The high phosphorus content and various forms in regenerated water are one of the important factors affecting scaling corrosion and microbial growth of circulating cooling water system. In this paper, inorganic phosphorus in simulated regenerated water was studied to investigate the migration and transformation of inorganic phosphorus and the effects of operation conditions and water quality conditions on it. The M-SMT method for quantitative qualitative analysis of inorganic phosphorus in scale body of simulation system was established by using the method of SMT continuous extraction of inorganic phosphorus from the sediment of river bed for reference. The specific forms and contents of inorganic phosphorus in dissolved inorganic phosphorus and scale body were determined, and the scaling and corrosion conditions in the system were analyzed, and the transfer and transformation of inorganic phosphorus in circulating cooling water system and scaling in the system were summarized. The effect of corrosion. The results show that the method of continuous extraction of inorganic phosphorus in the simulated system can be used to extract inorganic phosphorus completely, and the recovery rate is close to 100, and the inorganic phosphorus in different forms can be completely separated. The migration of dissolved inorganic phosphorus to the scale is mainly affected by the ion product of scale formation and the solubility product of the corresponding insoluble substance. In operation conditions, temperature is the main factor affecting the migration of inorganic phosphorus in liquid-solid phase. With the increase of temperature, the solubility product of insoluble matter decreases, and the migration rate, migration amount and mobility of dissolved inorganic phosphorus increase obviously. In the water quality condition, the increase of single inorganic phosphorus or hardness makes the scale formation ionic product increase significantly. Therefore, the transfer rate and amount of inorganic phosphorus increase, but affected by the concentration of scaling cations, the migration rate of inorganic phosphorus in water decreases with the increase of inorganic phosphorus concentration. Phosphate sediment is one of the major components of scale formation in the system, and the amount of scale in the system is proportional to the amount of inorganic phosphorus transport to some extent. When the concentration ratio was increased from 2 to 6, the amount of inorganic phosphorus transport in the system increased by 920 mg, and the scaling amount in the system increased from 2.85 g to 9.35 g. The effect of different conditions on the particle inorganic phosphorus is different. In operation conditions, the content of weakly adsorbed phosphorus decreases with the increase of flow rate, while the content of aluminum-bound phosphorus increases gradually. The increase of temperature can promote the conversion of aluminum-bound phosphorus to iron-bound phosphorus and calcium-bound phosphorus, and the effect of increasing concentration ratio on the four forms of inorganic phosphorus is the same, and the contents of the four forms of inorganic phosphorus are all increased, but the proportion of total particulate inorganic phosphorus does not change obviously. In water quality conditions, with the increase of inorganic phosphorus concentration, the amount of inorganic phosphorus migrating to solid phase increases, and the formation of weakly adsorbed phosphorus and calcium-bound phosphorus is the main factor, while the increase of total hardness in the system is conducive to the formation of calcium-bound phosphorus. The corrosion rate of the hanging sheet in the system is affected by the amount of scale, the content of weakly adsorbed phosphorus and the content of aluminum-bound phosphorus.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X131.2

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