Evaporative crystallizer, double-effect evaporation crystallizer, multi-effect evaporation crystallizer

Evaporation and crystallization Overview evaporative crystallizer www.wzgoody.com is a kind of mold, its internal structure design are similar forced circulation evaporator, because maybe kind of evaporator are available through the internal solvent concentrated under reduced pressure The crystal, of course, different materials also makes an important reason for our engineers design a different mold programs. Let Wenzhou Light Industry Machinery Co. gourdes for everyone part of the knowledge about the evaporator crystallizer to share with you. Evaporative crystallizer operating characteristics of the operation and its application crystallization process of crystallization is a saturated solution in the past to generate a new phase, involving solid-liquid equilibrium. Transitive specific target product lines, the need to experiment to determine the appropriate operating conditions of crystal, crystal products meet quality requirements, improve crystallization production capacity and reduce costs through process. Crystallization operation in question supersaturation increases supersaturation can increase the nucleation rate and growth rate, will help improve the crystal production capacity. 1. Assembly supersaturated spent problem: 1) nucleation rate is too fast, a large amount of fine crystals, crystallization is difficult to grow; 2) crystal growth rate is too fast, affect crystal quality; 3) the mold wall fouling prone to crystallization. There is a maximum degree of supersaturation, can guarantee a high rate of nucleation and growth at the same time, it does not affect the quality of crystals. Carried out under difficult to produce crystal dirt over saturation. 2. Solvent and pH of the solvent and crystallization operation pH value should be used in the target solute low solubility to improve crystallization yield mold. Solvents and pH on crystalline affected. E.g. procaine penicillin crystallized in an aqueous solution of a square crystal, crystallized from butyl acetate as a long rod. Crystallization operation required before designing experiments to determine the crystalline crystalline Preferred solvents and pH values. 3. Circulation flow rate of external circulation crystallizer http://www.wzgoody.com/Product/jjq/562.html, the cycle rate is set to be reasonable. 4. Improve circulation flow rate 1) in favor of eliminating the over saturation distribution in the machine, the device inside the crystal nucleation rate and growth rate distribution; 2) to increase the solid-liquid mass transfer coefficient, increase the rate of crystal growth; and 3) improve heat transfer efficiency, heat exchanger surface crystal suppress scale formation; cycle rate too high will cause wear of broken crystal. Whichever is greater value in the cycle rate should be no broken crystal wear range. If the mold has a crystalline grade features, cycle rate should not be too high, should ensure the normal functioning of classification functions. 5. Temperatures at different temperatures, crystalline and crystalline water generation will change, temperature control in a small temperature range. When cooling crystallization, if cooling too fast, the solution quickly reach a high degree of supersaturation, generating a large number of fine crystals, affecting the quality of the crystalline product. Temperature is preferably controlled between the saturation temperature and over-saturation temperature. When evaporation crystallization, evaporation rate too fast, the degree of supersaturation of the solution is large, fine crystals is generated, attached to the surface of the crystal, affect the quality of the crystalline product. Evaporation rate and the crystal growth rate should be adapted to maintain a certain degree of supersaturation. Industrial vacuum adiabatic crystallization operation is often evaporated, no external circulation heating apparatus, the evaporation chamber low temperature to prevent over-saturation of the dramatic changes. 6. Crystal dirt mold wall and circulatory system crystallization system to produce crystal scale, affecting the efficiency of the crystallization process. 7. Preventing or removing crystal grain scale scale method: 1) the use of the wall surface of the organic coating, to maintain a smooth wall, in the wall to prevent the two-dimensional nucleation occurs; 2) increase the crystallization rate of fluid flow system, the flow velocity distribution, eliminate low velocity zone; 3) If the outer loop liquid supersaturated solution, so that which does not contain the seed; 4) insulation jacket near the wall way to prevent over-saturation is too high; 5) the addition of the grain scale eradicate device, regularly adding solvent dissolution of the grain scale; 6) the evaporation chamber wall easily produce grain scale, can spray a solvent dissolving a crystalline scale. 8. Stirring and mixing the stirring speed is increased to improve the nucleation and growth rate, stirring rate will result in excessive shear crystal broken, influence the quality of the crystalline product. In order to obtain better mixing state, while avoiding crystallization of crushing, stripping hybrid system may be used, or the use of larger diameter or blade impeller, lower paddle speed. 9. Add the seed particles uniformly seed to the supersaturated solution is in the metastable zone. For higher solution viscosity of Mixture, nuclei difficult to produce, and in the high degree of fullness, once the nuclei, while there will be a large number of nuclei, polycrystalline phenomenon prone, difficult to control product quality. The high viscosity of the composition department at the metastable zone must add operation method of the seed crystal. 10. Object effects of coexisting crystalline impurity is a multi-component material system, to be selective crystallization target product. If the concentration of impurities is low coexistence, the target product is generally no significant effect on the crystallization. But if the crystalline impurities rising operation (such as using evaporative crystallization operation), the accumulation of impurities can severely affect the purity of the target product crystallized. Crystallization is necessary to control the operation content of impurities, impurity removal devices often added in the crystallization system. Ion exchange column or liquid waste. 11. Jing Jing pulp slurry concentration the higher the concentration, the unit volume of Crystallization larger the surface area, the faster the crystal growth rate, will help improve production speed crystallization (yield). But the crystal slurry concentration is too high, the suspension of illiquid, difficult mixing operations. Crystal slurry concentration should be taken within the maximum allowable range of operating conditions. In a batch operation, the amount of seed should be based on the size of the final crystalline product, meeting the highest concentration of high efficiency crystalline pulp production requirements.