Submerged condensers

Ullman and Letan [189] studied the effect of noncondensable gas on condensation of bubbles in a subcooled liquid. Bergles and Bar-Cohen [190] provide information on the use of direct contact condensation of bubbles in a so-called submerged condenser. Zangrando and Bharathan [191] established computer models to characterize direct contact condensation of low-density steam (with high noncondensable gas concentrations) on seawater. 

The Casale full condenser (6) is practically a submerged condenser and the carbamate flow obtained in this equipment is sent to the reactor. 

To overcome this problem, a submerged condensate pot is often installed instead of the steam trap (Fig. 17.le) as described earlier (item 5 above). An alternative remedy is replacing the steam trap by a level condensate pot (Fig. 17.1/). By varying the level control set point, the surface in the reboiler can be adjusted so that the reboiler operates at a pressure high enough to ensure condensate removal at all times without a pump. Note that the bottom of this drum is located below the bottom of the condensing side of the reboiler (189) otherwise, "dry reboiler operation at high rates will not be possible, and reboiler capacity will be reduced. 

Sour hydrocarbons from column condense in the shell of water-cooled submerged condenser. Tube bundle severely corroded due to concentration of acidic components near outlet, and needed frequent replacement. Adding a vent line from condenser to reflux drum and modifying controls to supply a small purge stream to condenser feed doubled tube life. 

Bolts or bolting—low temperature (20) Bolts or bolting—submerged condensers (32)... 

This is going to supply the cold water that courses through the condenser whether that condenser is set up for reflux or is part of a distillation configuration. The pump need not be very strong. In fact, the perfect example is one of those little, submergible fish tank pumps that one can find at any pet store for about 10. All the chemist does is attach a hose to the outlet, chunks the little pump into a bucket of ice water, attaches the hose to the condenser and there it is. An alternative source is that little pump that s attached to the windshield washing fluid reservoir of any car in a junk yard. The chemist removes the reservoir (pump still attached), applies an adapted power source to the pump and uses the plastic reservoir to hold the ice water. 

Most vapors condense inside tubes eooled by a falling curtain of water. The water is eooled by air circulated through the tube bundle. The bundles ean be mounted directly in a cooling tower or submerged in water. 

Gas-Fired water heaters are also made more efficient by a variety of designs that increase the recov-ei y efficiency. These can be better flue baffles multiple, smaller-diameter flues submerged combustion chambers and improved combustion chamber geometry. All of these methods increase the heat transfer from the flame and flue gases to the water in the tank. Because natural draft systems rely on the buoyancy of combustion products, there is a limit to the recovery efficiency. If too much heat is removed from the flue gases, the water heater won t vent properly. Another problem, if the flue gases are too cool, is that the water vapor in the combustion products will condense in the venting system. This will lead to corrosion in the chimney and possible safety problems. 

Maximum Flux at Critical Temperature Difference for Various Liquids Boiling in Pools Heated by Steam Condensing inside Submerged Tubes... 

Put the flask into the distillation apparatus after cooling thereafter add slowly 12 ml ddH20 followed by 12 ml of Soln. C. Heat the mixture to nearly 100 °C and the liberated ammonia is distilled by steam for about 10 min through a condenser, the tip of which is submerged in a flask containing 5 ml of Soln. D. When the distillation is finished (total volume about 25 ml), add three drops of E and titrate the ammonia with Soln. F. The results are calculated as follows ... 

On a manufacturing scale, an aq. soln. of hydrofluorio acid is made by gently heating the best quality of powdered fluorspar, free from silioa, to about 130° along with cono. sulphuric acid—containing 10 per cent, of water. The retort is a cast-iron pot with a cast-iron cover. The rim of the cover dips into an annular trough the joint is sealed with cone, sulphuric acid. The retorts are connected with a series of lead boxes as condensers. These contain water or dil. hydrofluorio acid to absorb the gas from the retorts. The condensers are submerged in water to keep them cool, and the acid so obtained is collected in leaden bottles. 

Aldol condensations were originally carried out in the liquid phase and catalysed homogeneously by acids or bases this way of operation is still predominant. Solid-catalysed aldol reactions can also be performed in the liquid phase (in trickle or submerged beds of catalyst), but in many cases vapour phase systems are preferred the factors determining the choice are the boiling points and the stability of the reactants at elevated temperatures. At higher temperatures, the formation of a, j3-unsaturated aldehydes or ketones [reactions (B) and (C)] is preferred to aldol (ketol) formation [reaction (A)]. A side reaction, which may become important in some cases, is the self-condensation of the more reactive carbonyl compound if a mixed condensation of two different aldehydes or ketones is occurring. The Cannizzaro reaction of some aldehydes or polymerisation to polyols or other resin-like products can also accompany the main reaction. 

Meanwhile, the tubes covered with stagnant water would begin to cool. The steam condensate itself around these tubes would cool. This cooled water would be colder than the saturation temperature of the condensing steam. The tubes would then be said to be submerged in subcooled water. 

It rather seems that 40 percent of the surface area of the radiator in Fig. 13.1 is submerged under water. If the water is drained out, does this mean that the rate of steam condensation will increase by the same 40 percent. Answer—yes Does this mean that the radiator heat transfer duty will increase by 40 percent Answer—not quite. 

The reason is condensate backup. The condensate backup causes subcooling that is, the liquid is cooled below its bubble point, or saturated liquid temperature. Perhaps a rat has lodged in the condensate outlet pipe. The rat restricts condensate drainage from the shell side. To force its way past the dead rat, the propane backs up in the condenser. The cold tubes in the bottom of the shell are submerged in liquid propane. The liquid propane is cooled below its bubble-point temperature. 

Note that the propane vapor is still condensing to propane liquid at 120°F. The condensed liquid is in intimate contact with the propane vapor, as it drips off the outside surface of the colder condenser tubes. The saturated propane vapor condenses directly to saturated propane liquid at 120°F. The saturated, or bubble-point, liquid then drips from the condensation zone of the condenser into the subcooling zone of the condenser. This is the zone where the tubes are submerged in liquid. 

The tower overhead vapor, shown in Fig. 13.6, condenses to a liquid on the outside of the cold condenser tubes. The liquid drips off the tubes. These droplets of liquid are in close contact with the saturated vapor in the condenser shell. This means that the liquid is in equilibrium with the vapor. The condensed liquid is therefore, initially, at its bubble-point temperature. This liquid accumulates in the bottom of the condenser s shell. The submerged tubes then must subcool this liquid. Part of the surface area of the condenser is hence devoted to subcooling liquid, and part is devoted to condensing vapor. 

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