The purpose of spray drying is to produce powder or a granular product in ONE step by drying 'atomized' liquid feed in heated air or other gaseous medium. By atomizing the feed into fine droplets, a very large surface area per unit mass is generated with a very short path for heat and mass transfer. The heated air supplies latent heat of evaporation to the droplets and brings about rapid drying which in turn brings about rapid cooling of the drying gas. At the same time the particle temperature is kept low by adiabatic cooling. Drying can take place in a very short time, typically 5-20 seconds.Spray dried particles are usually spheroidal, which gives the product excellent flow characteristics. Size of the dried product particle depends on the size of the droplet from the atomizers. Different atomizers produce different particle size distribution and spray patterns. The drying air flow pattern must be carefully selected for optimum performance.

Tubular falling film evaporators are widely accepted as the optimum type of evaporators for the concentration of most of the products within the dairy and food industry, pharmaceutical industry and within many sectors of the chemical industry. The liquid feed is distributed as a thin film inside a battery of verical tubes, and while the film is falling down through the steam heated tubes, water is eavporated from the film. Vapour from one effect is utilized as the heating medium in the following effect. A typical industrial-size falling film evaporator comprises equipment for pretreatment & pasturisation, 3-6 evaporator effects & equipment for after treatment, condensation & water cooling. Fitwell Engineering offer & supply a comprehensive selection of falling film evaporators, designed to meet almost any requirements of products viscosity, thermal characteristics, degree of concentration & rate of production.