Abstract:

In order to solve the problem of pipeline blockage due to the water scaling, the key idea that the crystallization fouling process was changed from passive to active was proposed in this research. In view of the injected water form oil field, galvanized iron was selected as the substrate. The mechanisms of the influences of alkali types and concentrations on crystal growth were revealed using dynamic simulation experiments，SEM, EDS and liquid turbidity tests. These results were showed that: The effects of five kinds of alkalis (such as Na₂CO₃, NaHCO₃, TEOA, Ca(OH)₂ and CaO) on scale mass gains, calcium loss rate and scaling induction periods were different. Among them Na₂CO₃ has a significant effeet on the loss of calcium loss, while CaO has a significant effect on the rate of fouling. Secondly, the morphology of the crystal is correlated with the alkali types. If the surface of the material was capable of forming a blocky shape scale or a layered fouling, this material was beneficial for the aggregation and deposition of crystals. Finally, the alkali concentration played a twofold role in the growth of fouling, that was, to promote the aggregation of crystal and to inhibit the scale growth. In other words, there would be a preferred range of alkali concentrations.

Key words: alkali, galvanized iron, fouling, calcium loss rate, crystal morphology

摘要：

为解决因水结垢造成的管线堵塞问题，提出了变被动结垢为主动结垢的思路。针对某油田注入水，以镀锌铁为研究基质，综合动态模拟剪切实验以及SEM、EDS和浊度测试，探究碱类型和浓度对CaCO₃污垢生长特性的影响机理。结果表明5种常用碱——碳酸钠Na₂CO₃、碳酸氢钠NaHCO₃、三乙醇胺TEOA、氢氧化钙Ca(OH)₂和氧化钙CaO对污垢结垢量、失钙率及结垢诱导期影响各异，其中Na₂CO₃对失钙速率影响显著，而CaO对结垢速率影响较为明显。其次，不同碱促使污垢形成不同的晶型晶貌，其中方块状和层状垢物易于在材料表面堆积，即有利于结垢。最后，碱浓度对污垢生长影响具有双重性，存在抑垢和促垢浓度区间。

关键词: 碱, 镀锌铁, 结垢, 失钙率, 晶型晶貌