低温等离子体技术预处理对稠油废水蒸发结垢的影响及其Visual Minteq分析

Influence of Non-thermal Plasma Pre-treatment of Viscous Oil Wastewater on Scaling Characteristics During Evaporation Process and Its Visual Minteq Modeling

稠油废水低成本蒸发回收是实现稠油开采的重要环节。蒸发过程中生成硅垢和碳酸盐会严重影响传热,为了抑制蒸发过程污垢的生成,采用低温等离子体(NTP)技术对稠油废水预处理后再蒸发,并对污垢进行分析检测。利用Visual Minteq软件模拟来自2个油田的稠油废水经NTP预处理后蒸发垢的组分。结果表明,经过NTP预处理,稠油废水的硬度、二氧化硅含量、金属离子含量和pH值均降低;蒸发过程中污垢热阻降低,污垢组分中硅垢减少,但主要组分未发生改变。Visual Minteq模拟结果与XRD分析所得污垢组分基本吻合,验证了NTP预处理阻垢机理,即NTP预处理降低了稠油废水中碳酸钙、镁和钙组成的双正离子碳酸盐以及硅和镁组成的盐的饱和指数。

Low-costevaporation is one of the most important measures to recover viscous oil wastewater in viscous oil recovery process, while silicate scale and carbonates scale formed during evaporation would deteriorate the heat transfer process. In order to avoid scale formation, non- thermal plasma （NTP） was employed to pre-treat viscous oil wastewater before evaporation and then the scale was analyzed. The Visual Minteq software was applied to analyze the dissolution/ precipitation equilibrium during evaporation process. It was found that after NTP pre-treatment the hardness, the pH value, the contents of silicon dioxide and metal of the wastewater were reduced. During evaporation, the heat transfer resistance of the scale was reduced, and the silicon content in the scale decreased, but the main composition changed little. The result of scale composition calculated by equilibrium modelling was well in agreement with that by XRD analysis. The anti- scale effect of NTP pre-treatment was verified by the decrease of saturation index forcalcium carbonate, dolomite, huntite and sepiolite.