Artisan’s Evaporation-Stripper column is the most cost-effective method of reducing volatiles in heat sensitive materials and viscous products to low ppm or ppb levels. The Evaporator/Stripper’s thin-film, disc-and-tube design offers unique advantages over conventional stripping technologies.
Principle of Operation
The feed into the Evaporator-Stripper enters from the top and cascades down over a series of (sometimes heated) tube and disk trays, where the volatile parts are stripped by the vapor introduced at the bottom of the column. The series of tube and disks provides a fresh liquid film at each stage. The extremely low pressure drop across the Evaporator-Stripper allows operation at a very high vacuum. Stripping is accomplished at the lowest practical temperature. For certain operations, Nitrogen is used as stripping medium instead of steam.
Typical Applications
- Solvent removal from polymers, surfactants, industrial coatings, fats, waxes, vegetable oils.
- Dehydration of organic peroxides or other highly flammable organics.
- Purifying aromatics, tocopherols, alkyl phenols, esters, oleochemicals.
- Recycling solvents, alcohols, ketones.
- Deodorization of polymers, additives, agrichemicals, fish oils, vegetable oils.
Evaporator-Stripper – Advantages of Operation
High heat and mass transfer
Short Residence time
The short residence time in the Evaporator/Stripper minimizes fouling, degradation, and discoloration of heat-sensitive products.
High turn-down ratio
Low pressure drop
Low operating Temperatures
The Evaporator-Stripper can operate at very low pressure (< 5 mbar absolute), which allows for very low process temperatures.
Self-draining design
The disc and tube design is self-draining and has no obstructions. The design can be adapted to handle very viscous applications (up to 8,000cP), foaming materials, and slurries containing solids. The design allows for an easy CIP or multi-product use.
Heated execution possible
The Evaporator-Stripper can be equipped with individually jacketed tubes, designed for steam or liquid heating. This execution permits simultaneous evaporation and stripping.
Low Maintenance
Evaporator-Stripper – Specific Examples
Problem
Safely and continuously dewatering of organic peroxides or other highly flammable or explosive organics.
Solution
Artisan’s patented falling-film disc-and-tube Evaporator/Strippers™ are utilized to dry organic peroxides used as curing agents in polyester and vinyl chloride polymerization. Low holdup volume and “no crevice” design make it the safest method for continuous drying of these highly flammable or explosive organics.
Example
Drying methyl ketone peroxide from 5000 PPM to less than 200 PPM, by countercurrent stripping, using argon as the stripping medium.
Problem
Stripping unpleasant odors, such as free fatty acids, and other odors causing volatile organic compounds from heat sensitive edible oils to non-detectable levels with no product degradation, or color formation.
Solution
Artisan proprietary falling-film Evaporator/Strippers™ are widely used to strip odor causing components from heat sensitive edible oils, and other heat sensitive products. Relatively short residence time (60 to 120 seconds), high surface to volume ratio, and extremely low pressure drop make it the most economical alternative to vertical wiped-film evaporators (WFEs). For stripping applications that are mass transfer controlled (i.e. diffusion limited), one Artisan multi-staged stripper can replace two or more WFEs.
Example
To deodorize cocoa butter by steam stripping the low molecular weight free fatty acids to non-detectable levels. Deodorization is accomplished at 10 torr, and relatively low temperatures (below 150 °C) to prevent intra-esterification, while utilizing an economically favorable 3% stripping steam rate.
Problem
Desolventizing and stripping organic solvents to very low (50 PPM or less) residual levels from concentrated vegetable oils containing emulsifying agents. Typically, these separations are carried out in wiped-film evaporators (WFEs), or packed columns. However, WFEs are single stage devices with limited mass transfer capability, requiring multiple passes, whereas packed columns offer excellent mass transfer, but cannot handle the viscosity.
Solution
Use Artisan’s unique falling-film disc-and-tube Evaporator/Stripper™, preceded by a rising film evaporator, to remove the bulk of the solvent and strip the oil to low PPM residual level by using either stripping steam, nitrogen, or both, depending on the desired moisture content of the final product. Stripping is carried out at moderate vacuum and relatively low temperature, resulting in higher product yield and quality, at reduced capital and operating cost.
Example
Steam strip hexane from vegetable oil containing lecithin – from 80% to 2 PPM without product degradation.
Remove methyl ester from crude coconut oil – from 50% to less than 1%.
Dehydrate crude vanillin from 20% to less than 50 PPM.
Remove hexane from marigold oleoresin – from 10% to 25 PPM.
Strip cholesterol from butter fat and lard to less than 100 PPM.
Problem
Devolatizing and deodorizing solution polymers.
Solution
Artisan’s patented falling-film disc-and-tube Evaporator/Stripper™ can effectively devolatize and strip to low PPM levels a variety of solution polymers in a single pass, without product degradation. Evaporator/Stripper’s high mass transfer capability greatly reduces stripping steam. Product quality is enhanced since stripping is carried out as a thin film, in a single pass.
Example
Reducing toluene in a heat sensitve epoxy resin polymer from 50% to less than 200 PPM in a single pass.
Continuous removal of residual styrene monomer from copolymer, from 3000 PPM to 8 PPM.
Continuous removal of ethyl acetate from photographic dye dispersion.
Continuous removal of high boiling volatiles from soap based latex emulsions.
Continuous removal of vinyl chloride monomer from aqueous copolymer emulsion.
