Crystallization Process Of L-Glutamine

There were some problems about L-Glutamine product, such as excess fines, wide particle size distribution and small density. These problems are disadvantage to separation of crystal and liquid, storage and transport and effect on price of L-Glutamine. Crystallization process is a key step to determine quality of products in Production process.Crystallization thermodynamics is the key foundation in most the production yield and the selection of crystallization process. Its solubility and metastable zone in the water and the mixed solvents of water-ethanol and water-acetone were obtained by the conductivity method. The effects of agitation intensity on the metastable zone widths were investigated. The results showed that L-Glutamine solubility and metastable zone widths increased with the increase of temperature. The metastable zone is wider in the mixed solvents of water-ethanol. In mixed solvents of water-ethanol, investigate the effect of stirring rate on metastable zone width. Metastable zone is widest in agitation intensity is 300 r·min-1.Crystallization kinetics is the basis for understanding of the crystallization behavior and crystallizer scale-up design. The nucleation and growth rate effect on crystal size distribution. This article studied on the kinetics of solventing-out crystallization and got the equations of nucleation and growth rate. The effect of Crystallization temperature and agitation intensity on nucleation and growth rate was discussed. The results showed that proper increase supersaturation is avail to crystal growth in low agitation intensity.L-Glutamine was recrystallized by solventing-out, cooling, grade electrcity point and vacuum evaporation crystallization method. Particle size and morphology were observed under electron microscope. The crystallization process of solventing-out and cooling was determined. The effects of operational parameters such as agitation intensity, seed and adding rate of ethanol etc. on the CSD, yield and morphology were investigated systematically by experiment. The experimental optimum operational conditions for the crystallization of L-Glutamine were finally obtained. Recrystallization specimen with the size of 3649μm, is 5 times compared to original sample. The product collect rate was 93.8% . Simulative industrial crude L-glutamine was recrystallized. Recrystallization specimen with the size of 1912μm, is 2.6 times compared to original sample. The results showed that glutamate, SO4-2 and Cl- effect on crystal shape and particle size distribution and restrain crystal growth.