Artisan’s Rototherm-P uses thin/wiped film evaporation to dry liquids or slurries to a free-flowing solid powder in a single pass. For many applications, it offers significant benefits over spray dryers and freeze dryers.
The Rototherm-P incorporates some special, custom-designed features:
- Robust mechanical design to handle higher torque requirements.
- All-welded ribbon blades allow space for free solids flow.
- Special extended auger section for powder discharge.
- Larger product outlet to facilitate ease of powder discharge.
Rototherm-P Benefits
The Rototherm-P has many advantages over other types of dryers.
Simple process
Low temperatures
Handling difficult products
High Turndown ratio
Reduced space for installation
Reduced energy
Little dust
Some Applications for the Rototherm-P
Problem
Producing free flowing powders with little or no moisture from liquid or slurry feed products.
Solution
Artisan’s Rototherm-P, a mechanically agitated thin-film processor, is widely used to produce free flowing powders from a variety of heat sensitive products. Rapid heat transfer, plug flow, and extremely short residence time make it the most versatile “single step” processor in the industry.
Example
Drying a heat sensitive “photographic dye” by evaporating the solvent from a 2% solution at reduced pressure. Pre-concentration in a rising film evaporator optimizes the size of the Rototherm. A rectifying column, using the Artisan proprietary Dualflo® distillation trays, controls solids entrainement.
Problem
Producing free flowing powders with little or no moisture from liquid or slurry food products in a single pass.
Solution
The Artisan Rototherm-P, a mechanically agitated thin-film processor, is widely used to produce free flowing powders from a variety of food ingredients. Rapid heat transfer, plug flow, and extremely short residence time permit concentration and drying of the most heat sensitive, foaming/fouling products from very dilute concentrations all the way to powder in one single positive pass through the Rototherm. In most applications, this eliminates one operating step; either a pre-concentration, or a drying step. In addition, significant capital and energy savings (factor of 2-3) are realized when Rototherm replaces a spray dryer. However, if the final moisture specification requires spray drying, a significant amount of energy is saved by feeding a more concentrated solution to the dryer, with the added benefit of preserving more of the valuable volatile flavor compounds.
Example
- Drying a heat sensitive protein containing fiber and starch by evaporating water from a 2% aqueous solution to a free flowing powder with a moisture content of less than 5%. This application eliminated freeze drying.
- Concentrating and drying an aqueous soy isoflavones stream from 2% solids to a free flowing powder containing less than 1% moisture.
- Concentrating and drying aqueous niacinamide from 50% moisture to a dry, free-flowing powder with no product degradation.
Problem
With conventional technologies it is extremely difficult to dry shear sensitive and viscous food additive products, such as lecithin. These highly viscous materials produce extremely low inside film coefficients in the laminar region, necessitating a mechanically agitated thin-film surface to create turbulence; and rapid surface renewal to obtain higher inside film coefficient. Additionally, temperature sensitivity limits the driving force (the temperature difference between the heating medium and the process) resulting in larger surfaces and longer residence times, both of which increase the risk of product degradation.
Solution
Use the Artisan Rototherm® thin-film evaporator for your most challenging drying applications. Rototherm offers superior heat transfer, negligible pressure drop, and is able to process foaming, fouling, and solids containing materials with ease. Unlike vertical wiped or thin-film evaporators that generally need an internal, or in some cases and external entrainment separator device, Rototherm, owing to its higher diameter to length ratios, and lower vapor velocities, does not require an entrainment separator in most applications.
Example
Continuously drying lecithin from a 50% solution to less than 1% moisture without product degradation. The water is condensed and reused in the plant. Dry lecithin is pumped and immediately cooled to prevent degradation.
Problem
Produce a free flowing powder from an aqueous animal protein solution without denaturing the protein.
Solution
Artisan’s Rototherm-P, a mechanically agitated thin-film processor, is widely used to produce free flowing powders from a variety of heat sensitive products. Rapid heat transfer, plug flow, and extremely short residence time make it the most versatile “single step” processor in the industry.
Example
Rototherm-P is used to dry aqueous solutions of animal proteins with an initial composition of 93% water and 7% animal protein. The material is dried under vacuum to a free flowing solid product. The short residence time in Rototherm P prevents thermal denaturing of the protein. And since a thin-film is created in Rototherm P without direct contact between the rotor and the wall, shearing and/or mechanical denaturing of the protein is prevented that would otherwise occur in a scraped surface evaporator.
