CAJ | 학술논문

用直接接触膜蒸馏处理高浓度的KCl和MgCl2溶液，考察了盐水浓度（1.0～4.0 mol·L?1）、循环流速（0.1～0.5 m·s?1）对膜蒸馏性能的影响；结果表明：随着盐水浓度的升高，膜通量下降，这是由于盐溶液的蒸汽压（即溶液中水的活度）下降的缘故；当浓度超过3.0 mol·L?1时，MgCl2溶液的膜通量出现负值，这主要归结为MgCl2溶液低的水的活度和高黏度的协同影响；提高循环流速，膜通量增大，尤其对高黏度的盐水（即 MgCl2溶液），增大流速对减少温度和浓度极化的影响更加有效。利用膜蒸馏-结晶耦合技术和间歇式操作，从高浓度KCl-MgCl2-H2O溶液中回收纯水和KCl结晶产品，考察了不同冷却方式对溶液过饱和度、KCl晶体形貌、粒度和粒度分布的影响。结果表明，自然冷却有利于形成形貌规整、粒度分布相对集中的结晶产品；在KCl降温过程中，自然冷却过程中的最大过冷度比快速降温过程小，从而有效地控制晶核形成的数量和晶体的生长速率。
용직접접촉막증류처리고농도적KCl화MgCl2용액，고찰료염수농도（1.0～4.0 mol·L?1）、순배류속（0.1～0.5 m·s?1）대막증류성능적영향；결과표명：수착염수농도적승고，막통량하강，저시유우염용액적증기압（즉용액중수적활도）하강적연고；당농도초과3.0 mol·L?1시，MgCl2용액적막통량출현부치，저주요귀결위MgCl2용액저적수적활도화고점도적협동영향；제고순배류속，막통량증대，우기대고점도적염수（즉 MgCl2용액），증대류속대감소온도화농도겁화적영향경가유효。이용막증류-결정우합기술화간헐식조작，종고농도KCl-MgCl2-H2O용액중회수순수화KCl결정산품，고찰료불동냉각방식대용액과포화도、KCl정체형모、립도화립도분포적영향。결과표명，자연냉각유리우형성형모규정、립도분포상대집중적결정산품；재KCl강온과정중，자연냉각과정중적최대과랭도비쾌속강온과정소，종이유효지공제정핵형성적수량화정체적생장속솔。
Highly concentrated KCl and MgCl2solutions were treated with direct contact membrane distillation (DCMD). The effects of salt concentration (1.0—4.0 mol·L?1) and circulation velocity (0.1—0.5 m·s?1) on permeate flux were investigated. Permeate flux decreased with increasing concentration, which was attributed to vapor pressure reduction caused by decrease of water activity in the solution. Reversed flux occurred in the DCMD process of highly concentrated MgCl2solution (>3.0 mol·L?1) under the test conditions, which was due to the combined effect of lower water activity and higher viscosity of the fluid. Permeate fluxes increased with increasing circulation velocity, which was more effective to reduce the negative effect of temperature and concentration polarization for MgCl2solution with higher viscosity. Membrane distillation-crystallization (MDC) of a highly concentrated solution of KCl-MgCl2-H2O was investigated for recovery of KCl crystalline product and pure water with batch operation mode. The effect of way of cooling on supersaturation of solution, morphology, and crystal size distribution was studied. KCl crystalline product with regular shape, tidy surface and concentrated particle size distribution was obtained by natural cooling and maximum degree of supercooling generated under natural cooling was lower than under quick cooling, which was beneficial to control nucleation amount and growth rate of KCl.