L-Lysine Sulfate Production from Glucose

The process under analysis comprises two major sections: (1) Fermentation; and (2) Product Concentration, Drying and Packaging.

Fermentation. The culture media used in fermentation is prepared by mixing process water, glucose and nutrients. The fermentation is performed in fed-batch mode and under aerobic conditions. At the batch phase, the microorganism seed is fed into the fermenters, which were previously filled with the fermentation batch medium. After glucose exhaustion, the batch phase is finished and the fed-batch phase is started, during which, glucose and nutrients are continuously supplied until the desired L-lysine concentration is achieved. At the end of the fermentation, the broth is sent to a buffer tank to provide a continuous flow in the further process steps.

Product Concentration, Drying and Packaging. The fermentation broth is thickened in a falling film evaporator under reduced pressure to a solids content of about 50 wt. %. Such solids are composed of free L-Lysine (about 55 wt%) along with biomass and other constituents of the fermentation broth. The concentrated broth is then fed to the Spray Granulator, a device in which the broth is sprayed over a fluidized bed and broth droplets undergo a granulation-drying process. The fluidized bed is produced by means of a current of air directed upwards, which keeps the particles in suspension while they are granulated and dried concomitantly. Final dry L-lysine Sulfate is obtained and sent to packaging line before being stored in bags.