化工单元操作双语翻译题.doc

翻译题 塔板下标的定义 Consider a single plate in a column or cascade of ideal plates. Assume that the plates are numbered serially from the top down and that the plate under consideration is the nth plate from the top。Then the plate immediately above this plate i5 plate n-l, and that immediately below it is plate n+1. （塔板符号定义） 考虑塔中只有单层塔板或多层理想塔板的蒸馏情况，假设这些塔板被从顶部往下连续编号，所研究的板为第n块，那么他上面紧挨的那块板为n-1，下方紧挨的为n+1。 2.（闪蒸情况）Flash Distillation Flash distillation consists of vaporizing a definite fraction of the liquid in such way that the evolved vapor is in equilibrium with the residual liquid ,separating the vapor from the liquid, and condensing the vapor. 闪蒸是在产生的蒸汽与剩余液保持平衡态的情况下使一定比例的液体汽化（蒸发），然后分离蒸汽，冷凝蒸汽。 3. （内部浓度变化） By definition of an ideal plate, the vapor and liquid leaving plate n are in equilibrium, so xn and yn represent equilibrium concentrations. This is shown in Fig. 4-8. Since concentrations in both phases increase with the height of the column, xn-1 is greater than xn and yn is greater than yn+1. Although the streams leaving the plate are in equilibrium, those entering it are not. This can be seen from Fig. 4-8. When the vapor from plate n +1 and the liquid from plate n-1 are brought into intimate contact, their concentrations tend to move toward an equilibrium state，as shown by the arrows in Fig. 4-8. Some of the more volatile component A is vaporized from the liquid, decreasing the liquid concentration from xn-1 to xn; and some of the less volatile component B is condensed from the vapor, increasing the vapor concentration from yn+1 to yn. 当从第n+1块板上上升的蒸汽和第n-1块板上下降的液体充分接触时，他们的浓度趋向于达到一个平衡态。由于两相中（易挥发组分）浓度随塔的高度而增加，xn-1xn , yn yn+1. 尽管流体离开塔时是平衡的，但进入的却不是。这个可以从表4-8中看出。当从第n+1块板上升的蒸汽和n-1块板上下降的液体充分接触是，他们的浓度趋向于达到一个平衡的状态，可由图4-8中的箭头可以看出。比较容易挥发的组分A中的一部分从液体中蒸发出来，使液体浓度从xn-1 下降到xn ，而挥发性较小的组分B中的一部分从气体中被冷凝，使气体浓度从yn+1 上升到yn 。 4.（精馏塔顶部冷凝）The condenser is often placed above the top of the column and the reflux pump and accumulator omitted Reflux then returns to the top plate by gravity. A speci