A Hydromechanical Study On Static Mixing Loop Reactors And The Application

We studied loop reactor?LR?and static mixing loop reactor?SMLR?by using mathematical modeling,computational fluid dynamics?CFD?simulation and experiments,aiming to uncover the macro-mixing performance,heat transfer and mass transfer performance,and reaction performance.The findings will theoretically underlie the popularization and application of reactors.Circulating pump and tubular loop were described by an axial diffusion model separately.Then the loop reactor residence time distribution?RTD?model with predictability and universality was built.The empirical equations of model parameters were determined experimentally.The numerical solutions of the models were determined via finite differential.The models were verified by RTD experiments to have reliable precision.A tubular loop reactor CFD model was built by using momentum source to simulate the circulating pump.The velocity field,pressure field and concentration field were determined by using steady-state computation and RTD was obtained by using unsteady state computation.The CFD model was validated by using Laser Doppler Velocimetry?LDV?experiment and RTD experiment.Sulfolene-synthesized tubular continuous process and loop reactor process were designed.The LR and traditional tubular reactor were compared under typical reversible exothermic short reactions.The conclusions are listed below.The RTD of LR can be described as follows:the RTD curve is multimodal,and the peak widths are very consistent;The peak height gradually decreases with time and finally approaches zero;the peak shape is gradually narrowed with time,then turns to be flat and finally disappears.The back-mixing characteristics of tubular loop reactor under high circulation ratio are very similar to the ideal continuously stirred tank reactor?CSTR?.The circulation ratio largely affects the back-mixing of tubular loop reactor,followed by Peclet number,and the least influential factor is the outlet position.The RTD of SMLR is very similar to that of LR.Compared with LR,the SMLR is featured by intensified inner fluid turbulence and higher favor for mass transfer and heat transfer.The effective shaft work of a circulating pump increases with the circulation ratio in a power function.The energy consumption is larger under a higher circulation ratio.The overall concentration distribution in a tubular loop reactor is very even,and its concentration variation coefficient is up to 10^-5.The Nusselt number and heat transfer area of a SMLR are both larger than a LR.Under the joint action of the two parameters,the SMLR outperforms the LR in terms of comprehensive heat transfer performance.The LR could regulate the residence time by changing the tube diameter and control the turbulent degree by altering the circulation ratio.The two regulations are independent and noninterfering,and thus show high heat transfer performance and outstand in chronic reactions.In summary,the LR and SMLR show back-mixing characteristics similar to the ideal CSTR,but outperforms in terms of mass transfer and heat transfer.The SMLR is better at mass transfer and heat transfer.The two reactors can be both widely into homogeneous reactions,and gas-liquid,liquid-liquid and liquid-solid heterogeneous reactions,and thus are ideal substitutes to CSTR.