Rolled Film Distillation Systems
Rolled Film Distillation systems are a type of wiped film evaporation system (WFE). Rolled film evaporation systems are similar to short path evaporators, except that they have an external condenser which offers a greater condensing area. Typically rolled film evaporation systems are ideal for producing larger batches and offer continuous feed. Rolled thin film distillation has an extremely efficient and even heat transfer regardless of the fluid viscosity. This allows you to reduce exposure time and increase productivity when operating on continuous mode.
Components Of Rolled Film Evaporation Systems
This roller wiped film system has proven it has tremendous advantages in many applications over the years. The roller system consists of a cylindrical “basket”, composed of guide rods on which rollers are fixed. The rollers are made of a glass fiber reinforced PTFE compound. The roller wiped film system is driven by a motor from outside the distillation chamber. The centrifugal force presses these rollers into the liquid film flowing downwards. Since there is no mechanical load on the evaporation surface, scratches and “fouling” are avoided.
How It Works
In rolled thin film distillation, the hot vapors travel through a bridge to the condensers. These condensers are cooled by a stream of chilled water, glycol, or other fluid which cause the vapors to condense and drip back into a collection vessel. Rolled film distillation is often used to purify materials that are difficult to distill using other methods, such as those with high boiling points or those that decompose at high temperatures. Rolled thin film distillation is often used in the pharmaceutical industry to purify active ingredients for drugs.
Advantages of Rollers Over Wipers
The roller wiped film system guarantees a uniform, laminar mixing of the thin film on the entire evaporator surface. Due to overlapping of the rollers on the unheated areas, so-called “dead-zones” are avoided. At the same time, the liquid thin film on the rollers is continuously renewed. This results in a very low residence time of the evaporating feed on the evaporator surface. Build-up or caking of material on the evaporator surface and on the rollers, which might happen with other wiping systems, is completely avoided with the roller wiped film system.
The large clearance between rollers and guide rods facilitates a “floating roller” which assures an even distribution of the feed material on the evaporator without causing damage to the evaporator. The necessity for a bottom bearing for the wiper basket is precluded by the floating action of the roller, so problems related to product penetrating into the lower bearing, or vacuum leaks through the bearing are eliminated.
Pros & Cons
While rolled film distillation offers many pros such as higher production rates, there are a few cons to be aware of as well. Due to the external condenser, the vapor cloud is significantly larger, resulting in a vacuum that is about 2 orders of magnitude higher than that of a short path system. Because of this, a wiped film system may not achieve a low enough atmospheric equivalent boiling point in order to avoid degradation to the distilled molecules. For this reason it is important to match the type of evaporator to the vacuum level required.
Pros of Rolled Film Distillation
- Ability for larger condenser surface
- Faster throughput
Cons of Rolled Film Distillation
- 1-2 orders of magnitude worse vacuum
- Better for lower boiling point material
Who is RFD Right for:
This type of distillation is especially well-suited for businesses in the food and beverage industry, as well as in the pharmaceutical, cosmetic and chemical industries. Cannabis & hemp also benefit from Rolled film distillation due to its ability to remove residual solvents and strip terpenes. In cases where a large amount of liquid needs to be produced in a short period of time, rolled film is the optimal choice especially when purity is of the utmost importance.
Getting Your Rolled Film Evaporation Systems
Chemtech is here to help you design your rolled thin film distillation system, and get you started on producing more efficiently, consistently, and confidently. When you buy from CTS, you will have a partner there for you when you need it most. We don’t just manufacture the highest quality distillation equipment, we also provide the best customer support available. Call today to learn more about how we can help design, set up and train you and your team on top of the line distillation systems.