Condensers tube bundle

The vapor composition at the top of the condenser (Y,i) is different from that at the bottom (Y, ). The condenser may be compared to a fractional distillation problem in reverse. Butane, having a higher boiling point, will condense out faster than the propane, although both are condensing at the same time. Thus, the vapor and liquid mol fractions from the top to the bottom of the condenser tube bundle are always changing. Proceed as follows The vapor at the top has the same composition as the gas leaving the evaporator. Therefore, Y,. = Y,. 

These data must be carefully interpreted to obtain overall heat-transfer coefficients for condenser tube bundles, e.g., horizontal condensers. Based on for a single tube, the condensing heat-transfer coefficient for a bundle, can be found from Eq. 3.4.6-22 of Ref. [2] ... 

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. 

I then asked the day-shift foreman if he had any thoughts on the cause of the high pressure drop across the tube side of the condensers. He indicated he really didn t know, but he wondered if it could have something to do with coke fines that accumulated in the fin passages of the condenser tube bundle. 

Further inspection revealed that the underside of the condenser tube bundle was encrusted with a thick layer of coke fines and dirt. I showed the foreman how to use strips of paper under the fin tube bundle to locate areas where the bundle was fouled enough to restrict air flow through the bundle. 

Reflux may flow by gravity to the tower, in which case the condenser and reflux drum (accumulator) must be elevated above the level of top tray of the tower. Alternatively, especially in order to obviate the need for elevated platforms and supports required for withdrawing the condenser tube bundle for cleaning, the assemblage may be placed at ground level and the reflux liquid pumped up to the top tray. Kern [28] describes the arrangements. 

Improved and redesigned rotors of modem compressors save considerable power. The ethylene fractionator and the propylene refrigeration condensers can be replaced with extended surface tube bundles instead of conventional tube bundles. 

Impingement Baffle The tube bundle is customarily protected against impingement by the incoming fluid at the shell inlet nozzle wmen the shell-side fluid is at a high velocity, is condensing, or is a two-phase fluid. Minimum entrance area about the nozzle is generally equal to the inlet nozzle area. Exit nozzles also require adequate area between the tubes and the nozzles. A full bundle without any provision for shell inlet nozzle area can increase the velocity of the inlet fluid by as much as 300 percent with a consequent loss in pressure. 

Depropanizer overhead condenser, top row of tubes, middle of tube bundle... 

A routine inspection of the tube bundle during a plant outage revealed fine cracks of the type shown in Fig. 9.11. Scattered longitudinal cracks were observed along the lengths of most tubes. The external surface was covered with a thin film of black copper oxide and deposits. The bundle had been exposed to ammonia levels that produced 14 ppm of ammonia in the accumulated condensate. 

Specimen Location Surface condenser tube, main condenser bundle... 

If I ever have to design an amine plant I will know, for example, that the temperature of the lean amine solution entering the absorber should be about 10°F higher than the inlet gas temperature to prevent hydrocarbon condensation and subsequent foaming, that the reboiler tube bundle should be placed on a slide about six inches above the bottom of the shell to provide good circulation, that about two percent of the total circulating flow should pass through the carbon towers, and many other necessary requirements. 

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. 

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. 

Just inside the shell of the tube bundle is a cylindrical baffle F that extends nearly to the top of the heating element. The steam rises between this baffle and the wall of the healing element and then flows downward around the tubes. This displaces non-condensed gases to the bottom, where they are removed at G. Condensate is removed from the bottom of the heating element at H. This evaporator is especially suited for foamy liquids, for viscous liquids, and for those liquids which tend to deposit scale or crystals on the heating surfaces. Vessel J is a salt separator. 

For purposes of standardisation, 19 mm outer diameter tubes of 1.65 mm wall thickness will be used, and these may be 2.5, 3-6, or 5 m in length. The film coefficient for condensing pentane on the outside of a horizontal tube bundle may be taken as 1.1 kW/m2 K, The condensation is effected by pumping water through the tubes, the initial water temperature being 288 K. 

Some sub-cooling of the condensate will usually be required to control the net positive suction head at the condensate pump (see Chapter 5, and Volume 1, Chapter 8), or to cool a product for storage. Where the amount of sub-cooling is large, it is more efficient to sub-cool in a separate exchanger. A small amount of sub-cooling can be obtained in a condenser by controlling the liquid level so that some part of the tube bundle is immersed in the condensate. 

Bench-scale tests were conducted to determine design parameters and operability of Che distillation process for the pilot plant. The column, reboller, and condenser used in the bench-scale system were constructed of fiberglass-reinforced ethylene-chlorotrifluoroethylene. The heat exchangers were spaghetti tube bundles constructed of fluorinated ethylene-propylene copolymer. 

Translate the heat-transfer area determined above into corresponding tube bundle dimensions. If different from those assumed in step (2), repeat steps (2) through (8) until satisfactory agreement is reached. The s-IVm method cannot be appHed to cases in which U varies along the tube length or the stream temperature profile is not smooth, ie, boiling or condensation is included. 

Once the steam pressure in the channel head of Fig. 8.4 falls to the pressure in the condensate collection header, the steam trap can no longer pass condensate. Water will back up in the channel head, and water-log the lower tubes in the tube bundle. This will lead to unstable steam flow control. This is especially true if the steam supply pressure is less than 20 psig higher than the maximum condensate collection header pressure. 

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