Development Of Cold Model Experimental Device For Airlift Loop Reactor And Study On Flow Characteristics Of The Reactor

Slurry bed hydrocracking process has great potential in deep processing of heavy oil with high content of metal and asphaltene. This process introduces a type of bubble column reactor, which has simple geometric structure, large phase contact area and high mass transfer efficiency. A kind of loop reactor is formed by adding a draft tube into bubble column, and it has many advantages compared with bubble column, for example, it has more directional flow, longer bubble staying time and higher mass transfer coefficient. Studying its flow characteristics can provide theoretical bases for the design, optimization and scaling-up of the reactor. Therefore, the goal of this thesis is to design cold model experimental device for airlift loop reactor and to research its flow characteristics by mathematical modeling and numerical modeling.In the beginning of this thesis, three types of cold model experimental device were designed for different research objective: one for reactor B-ALR, a kind of internal-loop airlift reactor with only gas flowing continuously under atmospheric pressure, one for reactor C-ALR, a kind of internal-loop airlift reactor with both gas and liquid flowing continuously under atmospheric pressure, the other one for reactor HP-ALR, a kind of internal-loop airlift reactor with only gas flowing continuously under high pressure. The structure and size of three reactors above were determined, and the operating condition and the experimental system as well. According to the feed way of liquid and the operating condition, differential pressure method was chosen to measure gas holdup for all the three reactors above, and the electrolyte pulse tracer method was chosen to measure liquid circulation velocity for B-ALR, and modified Pitot-tube method and floater method for C-ALR and HP-ALR respectively.By dividing the reactor into three zones and building model equations in each zone, a flow model was established based on theorem of momentum, two-phase flow drift-flux model of Zuber and Findlay and energy conservation theorem. Gas holdup and liquid circulation velocity of internal-loop airlift reactor with only gas flowing continuously were predicted by using the built model for the given reactor size, structure and experimental system under certain operating condition. The presented model was proven to be reliable to some extent by applying it to a reactor used in an article and by comparing the predicted results with the experimental results. The changing trend of gas holdup and liquid circulation velocity of B-ALR with the varying superficial gas velocity was studied by adopting the validated flow model.Half vertical section of internal-loop airlift reactor was chosen as the object of twodimensional numerical simulation, which was realized by introducing the Eulerian multiphase model and standard k ?? viscous model with CFD software Fluent 6.3. Proven to be reasonable by comparing the simulated results with the experimental results, the numerical calculation models and approaches were used to predicted gas holdup and liquid circulation velocity of B-ALR under different superficial gas velocities. What’s more, contours of phase volume fraction, axial and radial distribution of local gas holdup and liquid velocity, local liquid velocity vector were gained as well. Therefore, comprehensive information about the flow characteristics of B-ALR was obtained.