Design of Industrial Water-Based Polymerization Agitated Vessel by CFD Simulation

The agitated vessels are frequently used equipment in industries, especially in polymer processes. In the present work, the CFD simulation technique was used to study the effect of impeller shapes in the industrial scale water-based polymers agitated vessels to increase mixing efficiency. The VOF multiphase approach and 𝑅𝑁𝐺 𝑘−𝜀 turbulent model were used to study the hydrodynamic behavior of fluids in the vessel. The simulations were done in four designs, including designs A, B, C, and D. Designs A and B had three curved impellers with two 59° blades for each one and one straight impeller at the vessel bottom. Results showed that in designs A and B the gas phase entered the liquid (polymer) phase and caused foaming liquid. In design C, a geometrical modification was done by removing the top curved impeller, adding a blade for curved impellers, and reducing of curved blade angle from 59° to 26°. Results showed that wide rotational zones were achieved (about 75% of the illiquid phase), and the liquid foaming problem was solved in design C. The modification of the bottom impeller in design D showed that the rotational zones cover about 95% of the entire liquid phase, which is the best performance compared to other designs. Also, the performance of design D was evaluated at the viscosity values, including 7 𝑘𝑔/𝑚.𝑠, 4 𝑘𝑔/𝑚.𝑠 and 1𝑘𝑔/𝑚.𝑠 and mixing quality was validated at these values.