水热法耦合低温干化处理脱水油泥

Treatment of dehydrated oily sludge by hydrothermal coupled low temperature drying

含油污水在储存处理过程中会产生大量的脱水油泥(以下简称油泥),由于其具有高含水率,处置前通常采用热法进行干化预处理,但该方法却存在着油气回收困难、二次污染大、能耗高等缺点。为了给油泥干化和资源化利用提供更多的选择,开展了水热法预处理油泥实验——首先采用正交实验法确定最佳工艺条件为反应温度160℃、反应时间30 min、搅拌速度150 r/min;然后在反应时间、搅拌速度固定的条件下,考察了反应温度对油泥黏度、粒度和形貌的影响,分析了最佳工艺条件下油品回收率、沥青质去除率及水热处理对后续低温干化的影响;进而研究了水热处理前后油泥中油的高温模拟蒸馏馏分回收率、无机物组成等的变化情况。研究结果表明:①油泥的黏度随反应温度的升高而大幅度降低,粒度则随温度的升高而变小,表面形态随温度的升高而平滑致密;②水热处理不仅可以使油泥中的有机物发生分解反应,而且还可以使由活泼元素构成的无机物发生溶解;③水热处理后油泥干化速率高、干化时间短、干化后油泥松散。结论认为,较之于直接热干化,水热法耦合低温干化可节能42.44%,并且在最佳工艺条件下可回收42.3%的高品质油、去除72.3%的沥青质,具有良好的推广应用前景。

A large amount of dehydrated oily sludge(hereinafter referred as"oily sludge")is produced in the process of oily wastewater storage and treatment.Its water content is high,so thermal method is usually adopted to carry out drying pretreatment before it is disposed of,but this method has the disadvantages of difficult oil and gas recovery,serious secondary contamination and high energy consumption.In order to provide more options for oily sludge drying and resource utilization,it is necessary to carry out an experimental study on oily sludge pretreatment using a hydrothermal method.Firstly,the orthogonal experiment method was used to determine the optimal process condition,i.e.,reaction temperature 160℃,reaction time 30 min and stirring speed 150 r/min.Then,the influences of reaction temperature on the viscosity,particle size and morphology of oily sludge were investigated under the condition of fixed reaction time and stirring speed,and the influences of oil recovery rate and asphaltene removal rate on the subsequent low temperature drying under the optimal process condition were analyzed.Finally,the variation of the high temperature simulated oil distillation recovery rate and inorganic compositions in the oily sludge before and after the hydrothermal treatment was studied.And the following research results were obtained.First,with the increase of the reaction temperature,the viscosity of the oily sludge decreases greatly,the particle size reduces and the surface morphology gets smooth and tight.Second,the hydrothermal treatment can not only promote the decomposition reaction of the organic matters in the oily sludge,but also dissolve the inorganic matters composed of active elements.Third,after oily sludge is treated using the hydrothermal method,its drying rate is increased,drying time is shortened and the dried oily sludge is loose.In conclusion,compared with the direct thermal drying,the hydrothermal method coupled with low temperature drying can save energy by 42.44%.What's more,under the optimal process conditions,42.3% of high quality oil can be recovered and 72.3%of asphaltene can be removed,which indicates a promising popularization and application prospect.