Читать книгу Petroleum Refining Design and Applications Handbook - A. Kayode Coker - Страница 18

1 1. Complete recovery of dissolved solids is obtainable by evaporation, but only to the eutectic composition by chilling. Recovery by melt crystallization also is limited by the eutectic composition.

2 2. Growth rates and ultimate sizes of crystals are controlled by limiting the extent of supersaturation at any time.

3 3. The ratio S = C/Csat of prevailing concentration to saturation concentration is kept near the range 1.02–1.05.

4 4. In crystallization by chilling, the temperature of the solution is kept almost 1–2°F below the saturation temperature at the prevailing concentration.

5 5. Growth rates of crystals under satisfactory conditions are in the range of 0.1–0.8 mm/h. The growth rates are approximately the same in all directions.

6 6. Growth rates are influenced greatly by the presence of impurities and of certain specific additives, which vary from case to case.