The hydrodynamics of the fluid in the crystallizer is one of most influencing factors in the determination of the characteristics of the product crystals such as crystal shape,size,distribution,structure,purity etc.Accordingly,many studies have been attempted to investigate the influence of the hydrodynamic fluid motion on the crystallization phenomena of the crystal nucleation,growth,phase transformation,agglomeration etc,and to maximize his effect on the crystallization processes.Recently,a periodic fluid motion of Taylor vortex has drawn a great attention due to his unique hydrodynamic characteristics of high radial mixing and low axial dispersion.So,we have conducted intensive works on the application of the Taylor vortex to the crystallizations in order to enhance the crystal nucleation,growth and phase transformation.[1-3] In the anti-solvent crystallization of guanosine mono-phosphate (GMP),the phase transformation of amorphous GMP to the crystalline hydrate was highly promoted by the Taylor vortex because of the enhancement of the mass transfer for the dissolution of the amorphous GMP and growth of the hydrate crystals.So,the complete phase transformation could be achieved within 7 min of mean residence time in the continuous crystallization process.Comparing with the completion times of 120 min and 25 min in random eddy fluid motions in the batch and continuous modes,respectively,this result demonstrated clearly the high effectiveness of the Taylor vortex to the phase transformation [1,2].The crystallizer exploiting the Taylor vortex,called Taylor-Couette Crystallizer,has advantages in the process operation such as the multiple feeding strategy including the distributive feeding of the solutions along the axial position in the TC crystallizer [4].In case of the anti-solvent crystallization of GMP,the four feeding modes were available in the TC crystallizer.Among those,a distributive feeding mode of both GMP solution and anti-solvent was most effective in the phase transformation,reducing the mean residence time to 2.5 min for the complete phase transformation in the continuous operation.The promotion of the phase transformation by the multiple feeding mode was due to the regional supersaturation,mean residence time and mass transfer rate varying with the distributive feed input along the axial direction.A Taylor vortex was also used to promote the phase transformation of sulfamerazine (SMZ) [3].Even in a strong random eddy at high agitation speed of 3,000 rpm,the crystal nucleation of stable phase in the suspension of metastable seed crystals took more than 60 hours in acetonitrile (ACN) the solvent.Using a Taylor vortex,this phase transformation occurred within 3-7 hours with rotations because of the molecular alignment of SMZ in elongational fluid motion of the Taylor vortex.In the cooling crystallization,in addition,the polymorphic nucleation of the stable crystals was directly induced by the molecular alignment of the Taylor vortex.So,the phase transformation in the Taylor vortex was always many-fold faster than that in the random eddy.