The Oslo-type Evaporation Crystallizer, also known as the Crystal Crystallizer, is a mother liquor circulating continuous crystallizer. The feed material is added to the circulating tube, mixed with the circulating mother liquor inside, and then pumped to the heating chamber. After heating, the solution evaporates and reaches supersaturation in the evaporation chamber, entering the crystalline fluidized bed below the evaporation chamber through the intermediate tube (see fluidization).
In a fluidized bed crystallizer, supersaturated solutes deposit on the surface of suspended particles, promoting crystal growth. The fluidized bed hydro-cyclones the particles, with larger ones settling at the bottom and smaller ones rising to the top, resulting in the discharge of a more uniformly sized crystalline product from the bottom of the bed. The fine particles, along with the mother liquor, flow into a recycle pipe, where they are reheated to dissolve minor crystals. Replacing the heating chamber of an Oslo evaporation crystallizer with a cooling chamber and removing the evaporator, etc., forms an Oslo cooling crystallizer. The main drawback of this equipment is that solutes tend to deposit on the heat transfer surface, making operation cumbersome and limiting its widespread application.
Key Features
The Crystallizer, also known as the Crystal Crystallizer, features its main characteristic of having the region of supersaturation and the crystal growth area separately located in two different parts of the crystallizer. Crystals are fluidized and suspended in the circulating mother liquor, providing an excellent condition for crystal growth.
Operating Principle:
The crystallizer is a continuous crystallizer of the mother liquor recirculation type. The solution enters the fluidized bed of the crystallizer below the evaporation chamber through the intermediate tube. Inside the fluidized bed, the supersaturated solute in the solution deposits on the surface of the suspended particles, causing the crystals to grow. The fluidized bed hydraulically sorts the particles, with larger particles at the bottom and smaller ones at the top, and the crystalline product with relatively uniform particle size is discharged from the bottom of the fluidized bed. The fine particles in the fluidized bed are recycled with the mother liquor, dissolving minor crystals upon reheating. If the cooling chamber replaces the heating chamber of the Oslo evaporation crystallizer and the evaporation chamber is removed, it forms an Oslo cooling crystallizer. The main drawback of this equipment is that the solute tends to deposit on the heat transfer surface, making operation cumbersome and its application not widespread.