化工单元操作双语翻译题.doc

翻译题
1. 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-1>xn , 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 special valve, called a reflux splitter, may be used to control the rate of reflux return. The remainder of the condensate forms the overhead product.
冷凝器经常被放置在塔的顶部，而回流泵和储罐省略，这样回流的液体在重力作用下回流带到塔顶部的塔板上，一种特殊的阀门叫做回流阀，用来控制回流速率
，剩下的冷凝液形成了塔底产品。
5．（板式塔的设计）Important factors in the design and operation of plate columns are the number of plates required to obtain the desired separation, the diameter of the column, the heat input to the reboiler and the heat output from the condenser, the spacing between the plates, the choice of type of plate, and the details of construction of the plates.
板式塔的设计和操作过程中重要的因素是获得理想的分离效果所需要的塔板数，塔的直径，进入再沸器的热量和冷凝器中释放的热量，板间距大小，塔板类型的选择，以及塔板构造的详细资料。
6（再沸器）This limitation is removed by admitting the feed to a plate in the central portion of the column. Then the liquid feed flows down the column to the still, which in this type of plant is called the reboiler, and is subjected to rectification by the vapor rising from the reboiler. Since the liquid reaching the reboiler is stripped of component A, the bottom product can be nearly pure B.
如果让液体塔中间部分进料，则这种限制可以被避免，液体进料流向塔底部，这种类型的设备叫做再沸器。通过再沸器蒸发出来的蒸汽经行精馏，这样液体到达再沸器提溜A组分，塔底产品几乎接近纯组分B。

7. The vapors rising through the rectifying section are completely condensed in condenser C, and the condensate is collected in accumulator D, in which a definite liquid level is maintained. Reflux pump F takes liquid from the accumulator and delivers it to the top plate of the tower. This liquid stream is called reflux, it provides the downflowing liquid in the rectifying section that is needed to act on the upflowing vapor. Without the reflux no rectification would occur in the rectifying section and the concentration of the overhead product would be no greater than that of the vapor rising from the feed plate.（回流过程，作用）
从精馏段蒸发的气体被完全的冷凝在冷凝器C中，冷凝液被收集在储罐D中，在储罐中维持一定高度的液体，在回流泵F作用下将储罐中的液体重新送入塔顶部的塔板上。这股流体成为回流，在精馏段它主要提供向下的液体，这种液体是上升气体需要的，没有回流，精馏段就不能进行精馏操作，且塔顶产品的浓度将不会比进料板上升的蒸汽高。

8.（精馏提馏段操作线方程） Because there are two sections in the column, there are also two operating lines, one for the rectifying section and the other for the stripping section. Consider first the rectifying section. As shown in Chap. 18 [Eq. (18-7)], the operating line for this section is
(4-26)
Substitution for Vaya－Laxa from Eq. (4-23) gives
(4-27)
（由于塔中有两个部分，也有两条操作线，一个为精馏部分，另一个为提馏部分。首先考虑精馏部分。如18章方程18-7所示，这部分操作线方程为由方程4-23将Vaya－Laxa 替换，（方程）变为）
The slope of the line defined by Eq. (4-27) is, as usual, the ratio of the flow of liquid stream to that of the vapor stream. For further analysis it is convenient to eliminate Vn+1 from Eq(4-27) by Eq. (4-22), giving
(4-28
（直线斜率可以从方程4-27中定义，通常斜率是液体流速和气体流率之比。为进一步分析，用方程4-22来去掉方程4-27中的Vn+1是很方便的得到式 ）
For the section of the column below the feed plate, Eq. (18-7) becomes
(4-29)
As shown by Eq. (4-25), quantity Vbyb－Lbxb equals－BxB. and
(4-30)
（对于进料版以下的部分，方程18-7变为，如方程4-25所示 Vbyb－Lbxb 的量等于－BxB.，方程又变为 ）
This is the equation for the operating line in the stripping section. Again the slope is the ratio of the liquid flow to the vapor flow. Eliminating Vm+1 from Eq. (4-30) by Eq. (4-24) gives
(4-31)
这是提馏段操作线方程，斜率同样是气流与液流的比，通过方程4-24消除方程4-30的Vm+1得 。

9.（精馏提馏操作线斜率）In the rectifying column the vapor flow rate is greater than the liquid flow rate. In the stripping column the liquid flow rate is greater than the vapor flow rate. It follows that the slope of the operating line in the stripping column is greater than I and that of the operating line in the rectifying column is less than I.
在精馏段蒸汽的斜率大于流体的斜率。而在提馏段的液体的流率大于蒸汽的流率，相应的提馏段操作线方程的斜率大于1，而精馏段的操作线的斜率小于1.

10.(不同进料对塔中状态影响)In Fig. 4-15b the feed is assumed to be at its bubble point. No condensation is required to heat the feed, so V = V’ and L’=F + L. If the feed is partly vapor, as shown in Fig. 4-15c, the liquid portion of the feed becomes part of L’ and the vapor portion becomes part of V. If the feed is saturated vapor, as shown in Fig. 4-15d, the entire feed becomes part of V, so L =L’ and V = F + V’. Finally, if the feed is superheated vapor, as shown in Fig.4-15e, part of the liquid from the rectifying column is vaporized to cool the feed to a state of saturated vapor. Then the vapor in the rectifying column consists of(l) the vapor from the stripping column, (2) the feed and (3) the vaporization. The reflux to the stripping column is less, by the amount of vaporization, than that in the rectifying column.
（自己翻译的）在图4-15b中，假设泡点进料，冷凝液不需要加热进料，所以有V = V’和L’=F。如果进料为部分蒸汽，如图4-15c所示，进料液体部分会成为L’ 的一部分，气体会成为V的一部分。如果进料是饱和气体，如4-15d所示，进料会全部成为V的一部分，所以有L =L’ 及 V = F + V’.最后，如果进料是过热蒸汽，如图4-15e，精馏塔中的部分液体发生汽化去冷凝进料至饱和蒸气状态。之后精馏塔的蒸汽由（1）从提馏塔来的蒸汽；（2）进料；（3）（液体）汽化。由于汽化，回流至提馏段的液体比精馏段少。

11.（溶质回收再生）The solute is subsequently recovered from the liquid by distillation, and the absorbing liquid can be either discarded or reused. Sometimes a solute is removed from a liquid by bringing the liquid into contact with an inert gas; such an operation, the reverse of gas absorption, is desorption or gas stripping.
溶质通常通过蒸馏方法得到再生，而吸收的液体可以抛弃掉或重新利用，有时，一种溶质是通过将液体与惰性气体接触得以回收的，这个操作为气体吸收的逆过程，称为脱附和气体的提馏。
12. （填料材料） Thus most tower packings are made of cheap, inert, fairly light materials such clay, porcelain, or graphite. Thin-walled metal rings of steel or aluminum are some-times used. High void spaces and large passages for the fluids are achieved by making the packing units irregular or hollow, so that they interlock into open structures with a porosity of 60 percent or more.
这样，大多数塔的填料都是有价格便宜，惰性的，质量相当轻的粘土，陶瓷，或石墨等制成，有时薄壁的钢制或铝制的金属圈也能够用于制作填料，填料制作不规则形状或中空的，使他们具有60%的或更大的孔隙率的开放式结构。

13.（沟槽效应） Especially at low liquid rates much of the packing surface may be dry or, at best, covered by a stagnant film of liquid. This effect is known as channeling; it is the chief reason for the poor performance of large packed towers.
尤其是在较低的流体流速下，填料表面大部分是干的或者是表面停滞了一层液体膜，这种作用称为沟槽效应，他也是大的填料塔性能差的主要原因。