Sodium salt scaling, i. e. the formation of doubles salts comprised of sodium, carbonate and sulphate on the heat transfer surfaces, is a common problem that occurs during black liquor evaporation. In this study, experimental results are presented that provide new insights into the formation and composition of such scales and how they are influenced by the addition of tall oil brine. It was found that increased content of sodium carbonate and sodium sulphate in the black liquor increased scaling, while the ratio between carbonate and sulphate had a lesser influence than reported in other studies. Black liquor created loose clay-like scales comprised of aggregated crystals and black liquor, whereas salt solutions created hard mineral-like scales. The scales formed by both the black liquor and the salt solution showed a tendency to fall off during formation after primary nucleation. It was also found that both tall oil soap and alkalized tall oil brine could inhibit the formation of scales. The inhibition effect is stronger if adding the soap or brine just before scaling starts, but also depends on the amount added, the sodium carbonate and sodium sulphate content in the liquor as well as other factors.

中文翻译：

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黑液蒸发器中的钠盐结垢以及妥尔油盐水添加的影响

钠盐结垢，i。e。在黑液蒸发过程中，常见的问题是在传热表面上形成由钠，碳酸盐和硫酸盐组成的双盐。在这项研究中，提出了实验结果，为此类水垢的形成和组成以及妥尔油盐水的添加如何影响它们提供了新的见解。发现黑液中碳酸钠和硫酸钠含量的增加会增加结垢，而碳酸盐和硫酸盐之间的比率的影响则小于其他研究报告。黑液产生由聚集的晶体和黑液组成的松散的粘土状水垢，而盐溶液则产生硬的矿物状水垢。由黑液和盐溶液形成的水垢在一次成核后的形成过程中均显示出脱落的趋势。还发现妥尔油皂和碱化的妥尔油盐水均可抑制水垢的形成。如果在刚开始结垢之前添加肥皂或盐水，抑制效果会更强，但还取决于添加量，液体中碳酸钠和硫酸钠的含量以及其他因素。