Abstract The extent of the induction period preceding the inception of scale formation is of major interest in the design and operation of RO desalination plants. The objective of present work was to investigate induction time phenomena related to CaSO 4 scale precipitation from supersaturated solutions without or with the presence of a polycarboxylic acid based anti-scalant (AS). Membrane tests were carried out at different CaSO 4 supersaturation levels (0.75–4.20) and crossflow velocities (0.1–2.5 m/s) using both tubular and spiral wound membranes. Stirred beakers tests were also conducted. Membrane induction times in the flow systems increased linearly with the increase of flow Reynolds ( Re ) number from 80 to 6800 both without and with AS. The induction period in the presence of the AS was higher than that observed in AS free solutions. However, the extension of the induction period induced by the AS increased markedly with the Re number. Comparison of induction times measured in membranes and stirred beaker systems revealed a critical Re number below which induction time was shorter in the membrane system and above which the induction time was longer in the membrane system compared to the beaker test.

中文翻译：

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影响 CaSO 4 在 RO 膜上结垢诱导期的流动条件

摘要 在反渗透海水淡化厂的设计和运行中，规模形成开始前的诱导期的范围是主要的兴趣点。目前工作的目的是研究与 CaSO 4 水垢从不存在或存在聚羧酸类阻垢剂 (AS) 的过饱和溶液中沉淀相关的诱导时间现象。使用管状和螺旋缠绕膜在不同的 CaSO 4 过饱和度 (0.75–4.20) 和错流速度 (0.1–2.5 m/s) 下进行膜测试。还进行了搅拌烧杯试验。流动系统中的膜诱导时间随着流动雷诺数 (Re) 从 80 到 6800 的增加而线性增加，无论有没有 AS。在 AS 存在下的诱导期高于在无 AS 溶液中观察到的诱导期。然而，AS诱导的诱导期延长随着Re数的增加而显着增加。在膜和搅拌烧杯系统中测量的诱导时间的比较揭示了一个临界 Re 值，低于该值时，膜系统中的诱导时间较短，而高于此值时，与烧杯测试相比，膜系统中的诱导时间较长。