Venting condenser

A solution of phosphorus trichloride (137.3 g., 1.0 mole) in 1.51. of dry ether (Note 1) is added to a 3-1., three-necked, round-bottomed flask equipped with an efflcient stirrer, thermometer, a gas-inlet tube (Note 2), and a reflux condenser vented through a nitrogen reservoir (a T-tube under slight positive nitrogen pressure) into a well-functioning hood (Note 3). The flask is cooled in an ice bath to 0-5°, and an excess of anhydrous di-methylamine (Note 4) is introduced at such a rate that the temperature does not exceed 15°. The addition requires about... 

The first stage consists of five parallel groups of two series-connected towers, of which one group, lA and IB, are shown in Fig. 13.3. Feed for each lA tower consists of condensate from the reboiler of the associated IB tower. Feed is introduced at the top of the lA tower. Stripped vapor from the top plate is condensed in a barometric condenser, vented to a steam qector that maintains a pressure of from SO to 90 Torr at the top of the tower. 

Condenser design determines the extent of Rayleigh fractionation. Vertical upflow condensers ("vent or "inerts condensers (e.g.. Fig. 15.14c,e see Sec. 15.11) are intended to operate as Rayleigh fractionators. Other condensers which exhibit this fractionation behavior are unbaffled vertical downflow shell-side condensers (if baffles are included, they would interrupt the free fall of liquid), emd multipass horizontal in-tube condensers where liquid is segregated at the end of each pass. One case was reported (381) where this behavior caused severe inerts blanketing in an unbafiled, downflow shell-side condenser. 

Vertical in-tube condensers—upflow. This type of condenser is often termed inerts condenser, vent condenser, or knockhack condenser. It is used in some partial condensers when small quantities of vapor flow upward, while most of the condensate drains backward by gravity. Some fractionation takes place, and the mode of flow is similar to a wetted wall column. The most common distillation application of vent condensers is in internal condensers (below), or as a secondary... 

Correct piping is mandatory for the success of the hot vapor bypass control method. Bypass vapor must enter the vapor space of the reflux drum (Fig. 17.5d). The bypass should be free of pockets where liquid can accumulate any horizontal runs should drain into the reflux drum. If noncondensables are likely, vents are required on the condenser and drum. The condenser vent can be directed to the vapor space of the drum. Most important, liquid from the condenser must enter the reflux drum well below the liquid surface. The bottom of the drum (Fig. 17.5d) is the most suitable location. In one case (164) subcooled liquid entered the drum vapor space (presumably due to unflooding of the liquid inlet). The vapor space was 100°F hotter rapid condensation sucked the liquid leg between the drum and condenser into the drum in seconds. 

In Equation (11.16), it is assumed that mole fractions of water vapour and other gases (except water vapour) will be in proportion to their partial pressures. The saturation pressure of water vapour corresponding to the vent temperature of the ith-stage condenser is a function of the ith-stage condenser vent temperature ... 

A recording voltmeter for each supply circuit to the pumps and indicating ammeters for all motors over 50 HP will be provided. Radiation meters of suitable types will be placed at critical locations in the plant, such as near the discharge lines from the pile, in the fiash tank condenser vent, etc. 

If we assume that the reaction rate of 35 W kg" at 90°C doubles with every 10 K rise in temperature then at the boiling point (140°C) the rate will be an uncontrollable 1120 W kg". There are many engineering solutions to this potential hazard dump tanks, quenching, independent high-capacity condensers, venting to a catch tank and so on. All of these solutions are expensive and must work reliably on the rare occasions they will be required. 

Temperature of bottoms > design instrument fault/[column pressure > design] / high boilup/overhead condenser vent plugged/insufficient condensing, see Section 3.3. 

One problem with flooded condenser pressure control is related to the need to occasionally vent non-condensables. This vent valve must not leak when closed. Since the drum is normally full of liquid, a leaking vent valve will pass liquid. Many pounds of product can be lost in this way. A butterfly control valve with a soft, rubberized seat is a good choice for a remotely controlled, non-condensable vent valve. 

In the manufacture of polyvinyl chloride (PVC), an offgas stream is produced that contains unreacted vinyl chloride monomer. This stream is usually compressed and condensed to recover as much monomer as possible. However, the vent stream from the condenser still contains a significant amount of monomer. Baker et al. (1991) described an installation that recovers 100 to 200 Ib/hr of monomer from a condenser vent stream. The process vent stream is compressed to 63 psig and sent to a condenser operating at 14°F. The condenser vent stream, containing 30% vinyl chloride monomer, is sent to the membrane unit. The... 

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