4-1专业英语阅读【荐】.ppt

Unit 1 Unit Operations Arp 26th，2011 Ying, Xiaoguang lesson 1 Classification of Unit Operations Fluid flow This concerns the principles that determine the flow or transportation of any fluid from one point to another. Heat transfer This unit operation deals with the principles that govern accumulation and transfer of heat and energy from one place to another. Evaporation This is a special case of heat transfer, which deals with the evaporation of a volatile solvent such as water from a nonvolatile solute such as salt or any other material in solution. Drying In this operation volatile liquids, usually water, are removed from solid materials Distillation This is an operation whereby components of a liquid mixture are separated by boiling because of their differences in vapor pressure. Absorption In this process a component is removed from a gas stream by treatment with a liquid. Membrane separation This process involves the diffusion of a solute from a liquid or gas through a semipermeable membrane barrier to another fluid. Liquid-liquid extraction In this case a solute in a liquid solution is removed by contacting with another liquid solvent which is relatively immiscible(不混溶的) with the solution. Liquid-solid leaching(浸提) This involves treating a finely divided solid with a liquid that dissolves out and removes a solute contained in the solid. Crystallization This concerns the removal of a solute such as a salt from a solution by precipitating(沉淀) the solute from the solution. Mechanical physical separation These involves separation of solids, liquids, or gases by mechanical means, such as filtration, settling, and size reduction, which are often classified as separate unit operations. Lesson 2 Fractional distillation Fractional distillation is the separation of a mixture of compounds by their boiling point, by heating to high enough temperatures. Fractional Distillation in a Laboratory Apparatus 1. The apparatus is assembled as in the diagram. The mixture is