1、 Overview of OSLO Crystallizer:

OSLO crystallizer, also known as Oslo crystallizer or particle size grading crystallizer, has been widely used in industry and is a typical crystallizer commonly used in the salt industry. It is mainly used in the fields of salt, metallurgy, monosodium glutamate, water product processing, and soft water manufacturing. Its main feature is that the region where supersaturation occurs and the crystal growth zone are set at two locations in the crystallizer, and the crystals are fluidized and suspended in the circulating mother liquor flow, providing a good condition for crystal growth.

2、 Working principle of OSLO evaporative crystallizer:

The Oslo evaporation crystallizer is a typical mother liquor circulation evaporation equipment, which uses an external heater to heat the circulating materials inside the crystallizer, causing them to enter the vacuum flash chamber for evaporation to reach supersaturation state, and then enter the suspended bed through the central downcomer. In the crystal fluidized bed, supersaturated solutes in the solution deposit on the surface of the suspended particles, allowing the crystals to grow. A crystal fluidized bed is used for hydraulic classification of particles, with larger particles at the bottom and smaller particles at the top. Crystalline products with relatively uniform particle size are discharged from the bottom of the fluidized bed. The unsaturated solution in the upper section of the crystallizer enters the forced circulation pump to circulate and evaporate the material liquid for crystallization. During the material circulation process, clear mother liquor circulation is often used, and the crystals do not participate in the circulation, so they are not easily broken. The crystals are taken out from the middle of the crystallizer without settling restrictions, and the crystal growth environment is good, so the crystal particle size can be large, up to 6-20 mesh, or 3mm. No stirring is required inside the crystallizer.

3、 Design features of OSLO evaporative crystallizer:

1. The bottom of the crystallizer is in a circular arc shape, which improves the flow state of the liquid in the crystallizer and prevents the formation of dead zones;

The enlarged cross-section of the upper part of the crystallizer allows salt crystals to settle down and not participate in the cycle, reducing the chance of secondary nucleation;

3. The feed liquid is fed from the lower part of the evaporation chamber and discharged from the upper central tube, reducing the loss of short-circuit temperature difference. At the same time, during the rise of the feed liquid in the evaporation chamber, there is a process of particle dissolution, and the feed liquid changes from unsaturated to saturated, which can reduce the number of fine crystals and ensure the particle size of the salt;

4. During the design process, a mother liquor discharge pipe was installed on the conical part of the crystallizer, which can control the Na2SO4 content in the tank by discharging the mother liquor, and also discharge some fine salt crystals from the system to maintain the relative stability of the crystal nuclei in the tank and facilitate the growth of salt particles;

5. During the design process, consideration was also given to the method of retaining the feed liquid in the crystallizer during each tank brushing, which only brushes the heating chamber. This can avoid the loss of large salt particles in the crystallizer tank and shorten the time required to resume production of qualified salt after tank brushing.

6. The circulating pump motor adopts an adjustable motor, which adjusts the flow rate of the circulating pump by adjusting the motor speed, thereby adjusting the salt grain size in the circulating clear liquid and the number of crystals discharged from the system;