Condensation Vertical tubes

The apparatus shown in Fig. 38 can also be used for fractionation by placing a secure plug of glass wool at the base of the vertical condenser and then filling it with short pieces of glass tubing. 

The apparatus (Fig. 82), which is constructed throughout of glass, consists of a pear-shaped bulb A (of about 5 ml. capacity) in which the solution is boiled, and which has a short length of platinum wire fused through its lowest point to assist steady boiling. The bulb A is connected near its base by a curved narrow tube B to a vertical condenser C, and from its apex by a similar tube D, undulating as shown, to the cup E. A larger outer cup F is fused to the lower neck of E as shown. 

Fig. 1. Natural ckculation evaporators where C = condensate, E = entrainment return, F = feed, N = noncondensibles vent, P = product or concentrate, S = steam, V = vapor, and M = knitmesh separator (a) horizontal-tube, (b) short-tube vertical, (c) propeUer calandria, and (d) long-tube reckculating.

FIG. 11-122 Evaporator types, a) Forced circulation, (h) Siibmerged-tiihe forced circulation, (c) Oslo-type crystallizer, (d) Short-tube vertical, (e) Propeller calandria. (f) Long-tube vertical, (g) Recirculating long-tube vertical, (h) Falling film, (ij) Horizontal-tube evaporators. G = condensate F = feed G = vent P = product S = steam V = vapor ENT T = separated entrainment outlet. 

Numerous tubes in this new heat exchanger had suffered circumferential cracks of the t5fpe illustrated in Fig. 9.19. All cracking had occurred in the top of this vertical condenser, within 1 in. (2.5 cm) of the rolled areas in the vapor space (Fig. 9.20). 

Air cooled heat exchangers are used to transfer heat from a process fluid to ambient air. The process fluid is contained within heat eonducting tubes. Atmospherie air, whieh serves as the eoolant, is caused to flow perpendicularly across the tubes in order to remove heat. In a typical air cooled heat exchanger, the ambient air is either forced or induced by a fan or fans to flow vertically across a horizontal section of tubes. For condensing applications, the bundle may be sloped or vertical. Similarly, for relatively small air cooled heat exchangers, the air flow may be horizontal across vertical tube bundles. 

For vertical tubes, determine condensate loading G (Equation 10-73B). For these charts, G (viscosity in centipoise, at film temperature) is limited to 1,090. 

Flooding in an up-flow in a vertical condenser is an important design consideration, because this flooding poses a limit on flows for any selected design. To select the number of tubes required to obtain the area for up-flow without flooding, the diameter of the tubesheet to hold these tubes becomes quite large. The selected number of tubes, to... 

When considering commercial equipment, there are several factors which prevent the true conditions of Nusselt s theory being met. The temperature of the tube wall will not be constant, and for a vertical condenser with a ratio of AT at the bottom to AT at the top of five, the film coefficient should be increased by about 15 per cent. 

In a bank of tubes the condensate from the upper rows of tubes will add to that condensing on the lower tubes. If there are Nr tubes in a vertical row and the condensate is assumed to flow smoothly from row to row, Figure 12.42a, and if the flow remains laminar, the mean coefficient predicted by the Nusselt model is related to that for the top tube by ... 

In a horizontal shell-side condenser a dam baffle can be used, Figure 12.47a. A vertical condenser can be operated with the liquid level above the bottom tube sheet, Figure 12.47A... 

It is normal practice to assume that integral condensation occurs. The conditions for integral condensation will be approached if condensation is carried out in one pass, so that the liquid and vapour follow the same path as in a vertical condenser with condensation inside or outside the tubes. In a horizontal shell-side condenser the condensate will tend to separate from the vapour. The mean temperature difference will be lower for differential condensation, and arrangements where liquid separation is likely to occur should generally be avoided for the condensation of mixed vapours. 

For the case of vertical tube-side condensation from Exercise 11, the condensate is to be subcooled to 45°C. By dividing the condenser into two zones for condensation and subcooling, estimate the heat transfer area. 

Figure 8.14. Some arrangements of shell-and-tube condensers, (a) Condensate inside tubes, vertical upflow. (b) Inside tubes, vertical downflow, (c) Outside tubes, vertical downflow, (d) Condensate outside horizontal tubes. (HEDH, 1983, 3.4.3).

The thermal decomposition of ketene into carbon monoxide and ethylene is prevented, as far as possible, by the rapid removal of ketene from the hot tube, which is accomplished by the undccomposed acetone vapor. About half the acetone originally used should be collected unchanged as distillate by the vertical condenser. The yield of ketene will fall considerably if less distillate is formed. 

Procedure, ioo c.c. of the wine are evaporated in a flask to io c.c., allowed to cool and treated with 6 c.c. of the saturated ferrous sulphate solution and 4 c.c. of concentrated sulphuric acid.1 The flask is connected with a vertical condenser about 50 cm. long and heated carefully over a small flame so that excessive frothing of the mass is avoided. The distillate is collected in two or three well-cleaned tubes, each containing 2-3 c.c. of the iodide-starch paste acidified with 2 drops of dilute sulphuric acid the tubes are inclined so that the distillate flows down the walls. In presence of nitrites, a blue ring forms at the zone of separation between the starch and the distillate. 

Upper Limit Flooding in Vertical Tubes If, instead of a gas jet being injected into a liquid as in distillation, the liquid runs down the walls and the gas moves up the center of the tube, higher velocities can be achieved than shown by Eq. (14-168) or (14-203). This application is important in the design of vertical condensers. 

C. Dissolve about 5 mg of sample in 5 mL of water contained in a 50-mL distilling flask connected to a short, water-cooled, vertical condenser, the tip of which dips into a test tube containing 1 mL of a 1 50 solution of sodium hydroxide. Add 2.5 mL of hypophosphorous acid to the flask, then close the flask, heat at simmering for 10 min, and distill 1 mL into the test tube. Add 4 drops of cold, saturated ferrous ammonium sulfate solution to the tube, shake gently, then add about 30 mg of sodium fluoride, and bring the contents to a boil. Immediately add drops of 1 7 sulfuric acid until a clear solution results, and then add 3 to 5 drops more of the acid. A blue or blue-green color appears within a few minutes. Assay Not less than 96.0% and not more than 100.5% of C63H88CoN14014P, calculated on the dried basis. 

Fv = vertical tube loading, condensate rate per unit tube perimeter, kg/m s for a tube bundle... 

---