论文部分内容阅读
Food, pharmaceutical and natural extracts industries are essential in securing the development and the existence of human society.The feed materials for product formation are often of particulate form.The reason behind this is that the particulate mass presents large active surface area over its volume and is robust for application and transportation.It provides great ease in process handling including mixing, reacting, recycling and separating, and collecting.The particulate product from one step upper stream can be easily employed in a downstream process as the feed material.Among the methods of manufacturing particles, spray drying is the most productive method in turning liquid into solid particles.During spray drying, droplets from the atomizer can be made into particle form in a fraction of a second upon the exposure to hot gas (usually air).A single dryer capacity, for food industry, can be as high as tens of tons of powder produced per hour.For pharmaceutical industry, this capacity is much smaller, which may be as small as a few kilograms per hour.Big or small, the phenomena within a spray dryer are fairly similar.The process is fast but is complex, usually involving a wide droplet size distribution,diverse paths of the particles within the dryer hence a wide residence time distribution, hence different drying and thermal histories, and hence different reaction histories.The key to understand spray drying inducedparticle formation in a large drying facility is to quantify how one droplet turns into one particle.How the solid surface is assembled, induced by evaporation,is of crucial importance as this frontier surface is the first layer to be affected when incorporating into liquid in consumption (wetting for instance).How the inner structure is formed and the reaction history of this inner content affects considerably the solubility of the particle product upon application.The talk will focus on the pathway for the scientific combat of the above, based on the developments of Single Droplet Drying Platform and Mono-disperser Droplet Spray Drying Devices.