利用生物质发酵制备气泡水焦浆的机理研究

Petroleum coke water slurry is prepared easily by mixing petroleum coke, water and additives together, which is a kind of substitute fuel for oil with high concentration and high thermal value. But dilatant rheological characteristics and inferior stability have restricted development and application of petroleum coke water slurry. However, current studies mainly focus on mixing sludge, ash or special stabilizing agent, which all have the malpractice of reducing slurrying concentration and thermal value greatly. Recently, we found that the presence of bubbles in slurry not only could improve stability, but also could increase slurrying concentration and pseudoplastic characteristics. Therefore, this project presents a new preparation method of bubble petroleum coke water slurry by means of biomass fermentation and gas - solid adsorption, which makes bubbles disperse equally in slurry and makes the slurry have high quality. In the dispersive multielement system of “petroleum coke - biomass - water - additive - bubble”, harmonious effect mechanism of all kinds of components during slurrying process will be researched. Microcosmic physics character and adsorption mechanism of bubbles and particles in the slurry will be studied, and meanwhile bubble-particle complexes theory model will will be built, showing slurrying mechanism of bubble petroleum coke water slurry. The research results are significant for relieving the pressure of petroleum import and promoting development of substitute fuel for oil. Preparation of bubble petroleum coke water slurry based on biomass fermentation will probably prove to be a milestone in the history of slurry fuel.

石油焦易与水、添加剂混合制成高浓度、高热值的浆体代油燃料——水焦浆，水焦浆的胀塑性流变特征和较差稳定性，严重制约了它的发展与应用。而当前研究主要聚焦于掺混污泥、灰渣或专用稳定剂等方面，均具有大幅降低水焦浆成浆浓度和热值的弊端。申请人前期预研表明水焦浆中气泡的存在不仅能够大大改善浆体稳定性，还有助于提高成浆浓度、增强假塑性流变特征。鉴于此，本项目提出利用生物质发酵技术，在水焦浆中形成均匀分散的气泡，依据气固吸附原理，制备高浓度、假塑性、稳定均质的高品质浆体燃料——气泡水焦浆；探索“石油焦-生物质-水-添加剂-气泡”多元分散体系中各组分在成浆过程中的协调作用机理；研究气泡与颗粒在水焦浆中的微观物理特性与吸附机理，构建气固联合体理论模型，揭示气泡水焦浆成浆机理。研究成果对缓解我国石油进口压力、推动代油燃料的研究进展具有重要意义，有望成为浆体燃料发展史上的里程碑式变革。

为了提高水焦浆的稳定性、改善水焦浆的流变性，本研究通过理论分析和实验研究相结合的方法，根据对代油燃料的品质要求，对利用生物质发酵制备气泡水焦浆进行了基础研究。各类生物中，以单糖型水焦浆的成浆性和稳定性最好，其次是淀粉型生物质，再次是纤维类生物质；单糖和淀粉类生物质的添加量以2%为宜，纤维类生物质的添加量以3%为宜，最佳成浆浓度高达66%以上，最佳倒出率均可达80%以上。酵母菌作为发酵剂时的成浆性和稳定性均高于活性污泥。随着污泥用量的增加，气泡水焦浆的成浆浓度迅速下降，可流动性变差。当污泥用量为15%时，成浆浓度均低于60%，可倒出率均低于40%。生物质发酵产气大致经历了发酵初期、中期和后期三个阶段。当使用酵母菌为发酵剂时，发酵产气量主要在发酵初期（24小时内）完成，发酵产生的气泡迅速分布在浆体内部，与石油焦颗粒充分结合，在石油焦颗粒聚结沉降之前形成气固联合体，维持浆体的稳定性；当使用污泥为发酵剂时，发酵产气量大部分在发酵中期（第2~3天）和发酵后期（第4~7天）完成，发酵速度缓慢，时间长，在石油焦颗粒聚结沉降之前无法保证有足量的气泡与之结合形成气固联合体，因此污泥型气泡水焦浆效果欠佳。生物质的加入可以使气泡水焦浆获得理想的假塑性流变特征，流动特征指数可以达到0.7左右。石油焦颗粒强疏水性表面易与气泡相互粘附，形成气固联合体，借助气泡的提升力和空间位阻，使石油焦颗粒稳定悬浮，形成稳定的气泡水焦浆。气固联合体结构越稳定，气泡水焦浆的稳定性越好。浆体的屈服应力越大，越有利于气固联合体的构建，气泡水焦浆的稳定性越好。研究结论对水焦浆稳定性问题的解决，对石油焦和生物质的高效清洁利用，对液体燃料和代油技术的发展等均具有积极的作用。