Single-Effect Evaporators Principle And Applications

The principle of single-effect concentration equipment is to utilize a single evaporator to vaporize the solvent (mostly water) in a solution through heating, then recover the solvent through condensation, thereby increasing the solution concentration. The entire process involves only a single evaporation-condensation cycle.

I. Structure (Four Major Components)

1. Evaporator: This core heats the vaporization zone, commonly jacketed or shell-and-tube. Steam is used to heat the solution inside and outside the tubes, bringing it to boiling point.

2. Separator: Located above the evaporator, this separates the vaporized solvent vapor from the concentrated solution, preventing solution droplets from entering the condensation system with the steam.

3. Condenser: This cools the solvent vapor, liquefying it into a recoverable solvent (such as water). Cooling water is typically used for heat exchange.

4. Vacuum Pump: This reduces the pressure within the equipment, lowering the boiling point of the solution (for example, the boiling point of water can be reduced to below 60°C under vacuum). This pump is suitable for heat-sensitive materials.

II. Typical Applications

Food Industry: Concentrating juice, milk, syrup, honey, etc. Low-temperature evaporation preserves flavor and nutrients.

Pharmaceutical Industry: Concentrates traditional Chinese medicine decoctions, antibiotic extracts, and vitamin solutions to prevent high temperatures from destroying active ingredients.

Chemical Industry: Treats inorganic salt solutions (such as sodium chloride and zinc sulfate) and recovers organic solvents to purify materials or reduce wastewater.

III. Single-Effect Concentrator Operation Procedure

1. Preliminary Preparation: Check the connections and seals of all equipment components (evaporator, separator, condenser, and vacuum pump) to ensure there are no leaks. Clean the interior of the equipment to prevent residual impurities from contaminating the material. Set the heating temperature (usually 60-80°C) and vacuum level (usually 0.06-0.08 MPa) based on the characteristics of the traditional Chinese medicine decoction.

2. Feeding Phase: Open the feed valve and slowly feed the traditional Chinese medicine decoction into the evaporator via the feed pump, controlling the feed volume to approximately 2/3 of the evaporator's volume. Close the feed valve.

3. Heating Concentration: Start the vacuum pump to draw vacuum. Once the equipment reaches the set vacuum level, open the heating steam valve to heat the decoction through the jacket or tubes. Closely monitor the state of the solution in the evaporator. When the solution begins to boil and vaporize, adjust the steam pressure to maintain stable heating.

4. Separation and Condensation: The solvent vapor generated by vaporization rises to the separator. After separation, the pure steam enters the condenser, where it exchanges heat with cooling water and liquefies. The liquefied solvent (water) flows into a collection tank for recovery; the concentrated drug solution remains in the evaporator.

5. Discharge and Cleaning: When the drug solution concentration reaches the set requirement (which can be checked with a density meter or empirically), first close the heating steam valve, then turn off the vacuum pump. Once the pressure inside the equipment returns to normal, open the discharge valve to release the concentrated drug solution. Finally, rinse the interior of the equipment with clean water or a dedicated cleaning agent to complete the cleaning.