油浆定向裂解制备富芳烃油与协同脱固技术基础研究

Fluid Catalytic Cracking (FCC), as one of the most important processes for petroleum secondary conversion, produces a majority of gasoline and diesel and will continue to serve as a platform technology for multi-products in the future. Fine particles, such as catalyst and coke powder, transform into slurry oil at tower bottom during FCC process. The difficulty in efficient and large-scale utilization of oil slurry with high solid contents has greatly restricted the development of FCC process because of the inferior feedstock, as well as demands of clean products and chemicals. Based on the separation of characteristic components, the cutting of narrow boiling points and their characterization in a molecular level, the present study will first deepen the understanding of structural properties, the behavior of particle distribution and their hosting properties in slurry oil. The phase separation and fine powder transforming behaviors of colloid system in slurry oil will be revealed during the thermal conversion. The operation conditions can be optimized to enhance the synergistic effects between the asphaltene condensation and fines flocculation for “coking and solid removal”, thus to realize the oriented conversion of “light components cracking” for oil-gas, and “heavy components coking” for particle solidification. Further via synthesizing the results of slurry oil cracking, coke characterization and its gasification characteristics, the internal relationship between fines (i.e., catalyst, coke particles) migration-solidifying and coke gasification was illuminated to explore a new technical route for efficient solid removal and value-added utilization of slurry oil.

油浆中颗粒与重组分的胶连作用制约分离过程，强极性稠环芳烃吸附-反应导致热转化生焦严重，因此传统油浆净化-芳烃富集过程难以满足劣质油浆加工要求。为实现低质油浆的高效利用，项目提出基于沥青质易生焦倾向性，实现协同脱固以及特征组分定向转化制备富芳烃油的思路。通过特征组分分离、窄馏分切割及其分子层次表征，研究固体颗粒分布迁移规律及微结构特征，揭示固体细粉与沥青质分子的物性及其赋存关系；通过热台显微镜观察不同固含量油浆的液相生焦过程，获得多条件下油浆反应与颗粒迁移基本规律，解析热转化相分离过程与颗粒团迁移长大协同机制；在此基础上提高反应尺度，采用积分与微分流化床反应器，通过调控温度、催化剂结构与活性，实现油浆中饱和分裂化、芳香分保留、胶质缩合与沥青质生焦等定向转化过程，获得特征组分的吸附-反应行为及其动力学特性，揭示定向转化与颗粒脱除的耦合作用机制，为炼厂油浆制备富芳烃油与协同脱固提供科学依据。

催化裂化油浆，是指原油在催化裂化工艺过程中组分重、高固含量的塔底渣油。油浆富含芳烃组分，然而高固含量及其与重组分的胶连作用制约分离过程，生焦倾向严重。本研究充分借助细粉颗粒在生焦过程中的“焦核”作用，提出油浆轻度热裂化制备富芳烃油品同时协同脱固的一步法过程，面向炼化一体化发展趋势，具有鲜明的需求导向特性。研究中首先开展油浆的固含量测定及其表征，然后通过裂解反应协同脱除固体细粉，进行油浆定向转化、载体筛选与工艺可行性验证，所得主要结果包括：.（1）油浆固含量测定及组成分析。采用灰分法、过滤法、离心法测量了油浆的固体颗粒含量，并对比分析。结果表明，油浆中重组分与细粉颗粒存在较强的吸附作用，油浆中的固体颗粒呈现不规则的块状分布，粒径在0.4-40 μm之间，颗粒组成主要有细粉催化剂、焦粉和无机盐、碱金属K、Ca以及金属Sb、Fe等。.（2）劣质重油热解性能研究。通过热重分析仪对油浆、渣油、沥青等重油热解反应特性及气体释放规律进行研究，三种原料的热解反应温度区间分别为211~440℃、179~460℃和386~511℃，相应的热解活化能分别为73.48~105.19 kJ/mol、56.77~178.91 kJ/mol和131.46~211.71 kJ/mol。.（3）油浆裂解脱固特性研究。采用自制反应装置，选取石英砂、焦粉与催化剂进行油浆裂解实验，结果表明对油浆裂解产物分布影响最大是温度，其次是剂油比，蒸汽油比影响最小。石英砂活性低、不宜作为油浆裂解的载体。焦粉与催化剂最佳的裂解条件为：温度470 ℃，剂/油比5.7，蒸汽/油比0.5。催化剂和焦粉孔道丰富，并具有一定的催化活性促进生焦等反应，更容易沉积油浆中的固含物，芳烃富集效果更好。.（4）油浆富芳烃油品及其可行性验证。裂解油的红外及GC-MS结果表明，流化热转化实现了油浆中芳烃组分的富集，裂解油品收率超过70 %，裂解后脱固率达到96 %，1-4环芳烃含量达到85 %。热载体循环利用实验结果表明，焦粉裂化效果的稳定性较好，细粉起到结焦成核作用，验证了焦粉以及掺混催化剂作为油浆与煤焦油等劣质重油改性接触剂的可行性。