Feeding is carried out by vacuum feeding. Therefore, during operation, start the vacuum pump and open the feed valve simultaneously. To ensure a certain evaporation space, the liquid level in the tank should be kept close to the sight glass of the cylinder. After closing the feed valve, open the jacket steam valve to make the material liquid in the tank boil moderately and start evaporation. To accelerate the process, decompression concentration is adopted, and the level of vacuum degree is determined by users’ different requirements.
The operation can be divided into two types: continuous and batch. For continuous feeding with decompression process, a flowmeter should be installed on the feed pipeline to control the feed amount. The flow range is determined according to the volume of the concentration tank. The feeding height should be controlled to prevent the liquid level in the tank from exceeding the sight glass of the cylinder. However, many pharmaceutical factories currently adopt batch operation, which is simpler and more convenient but with lower efficiency. Discharging can only be performed after the tank returns to normal pressure, so it is batch discharging.
The concentration principle of this equipment is relatively simple: the extraction liquid is heated to boiling to evaporate water. The foam containing effective components in the secondary steam (evaporated steam) is separated by the vapor-liquid separator and refluxed to the cylinder to avoid waste. The evaporation intensity is generally 50~60 kg/m²·h. Due to structural limitations and facilitate cleaning, the specific gravity of the concentrated liquid should not exceed 1.2~1.25 kg/m²·h; otherwise, it will bring difficulties to discharging and cleaning.
