Have you encountered any problems with the evaporation process?

1.Have you encountered any problems with the evaporation process?

Salt precipitation produced in the evaporation process: If the material contains inorganic salts and organic acid calcium salt components, such as CaSO4, Na2SO4, NaCl, a class of strong acid salts, in the supersaturation will be precipitated on the surface of the heat transfer. Especially like the water of no crystallization of CaSO4 and other solubility with the increase in temperature and reduce the salts, evaporation will be accelerated in the heat transfer surface salt precipitation and the generation of hard scale layer. Other salts such as CaCO3, Ca(OH)2, Mg(OH)2, etc. generate a soft scale layer.

Material liquid in the evaporation process to produce adhesion: material liquid contains suspended and colloidal substances, such as traditional Chinese medicine extracts, antibiotic fermentation solution, containing proteins, starch and other flocculent suspensions, sugar solution contains colloidal silicon oxide, alumina, iron oxide, and other oxides in the concentration process is easy to adhere in the heat transfer surface and the formation of scale layer.

Material liquid in the evaporation process to produce coking: material liquid in the heat-sensitive substances, or due to high viscosity, heat transfer surface is not smooth and hanging liquid, in the heat transfer surface of the local overheating or in the dry wall at the residence time is too long, due to chemical changes and coking to form a hard scale layer.

2. Scale prevention and removal measures

Methods of controlling scale adhesion: adding crystal seed method, controlling supersaturation, electromagnetic anti-scaling, etc;

Chemical methods of descaling: alkaline boiling method, acid immersion boiling method;

Physical methods of descaling: polycooling method, high-pressure water spray washing method;

Operation of the anti-scaling layer of several measures: pretreatment in addition to the, improve the circulation rate, drain the hot water to clean the dissolution, regular clear accumulation of scale, concentration control;

3, the temperature difference of the evaporator should not be too large

If the temperature difference between the heating steam and the material liquid exceeds the critical temperature difference limited by the tube material and the solvent, not only does the total heat transfer coefficient drop, wasting thermal energy, but also tends to produce dry wall phenomenon and promote the formation of scale buildup in the tube. Maintain a temperature difference of 5-12°C for optimum operation.

4、Vacuum system of evaporation device

Ensure that the vacuum degree required for hair vacuum evaporation operation and its stability. Otherwise, the fluctuation of vacuum degree will lead to the change of feed rate, material boiling point, secondary vapor temperature and so on, thus destroying the normal operation.

There are several main reasons for the decrease in vacuum level

Causes of the vacuum system itself: clogged filters, stuck check valves, insufficient cooling water, high water temperature;

Increase in the amount of gas: low concentration of liquid material, large amount of secondary vapors, many gases entrapped in the liquid material itself, leakage of the device;