Reboiler connections

Figure 3. Vertical thermosyphon reboiler connected to tower.

This network has only one reboiler connected with the section where the heaviest component 3 is obtained and one condenser connected with section where the hghtest component 1 is obtained. We have a classical Petlyuk column for ternary mixture separation. Four thermodynamically equivalent groupings of sections into two columns are possible for this column ... 

If specified, reboiler connections are usually located at the bcMtom section of the tower. For the horizontally mounted thermosiphon reboiler, the drawoff nozzle is located just below the bottom tray. For the vertically mounted recirculating thermosiphon reboiler, the draw-off nozzle is located at the bottom head. For both systems, the return nozzles are located just above the liquid level. Exhibit 10-31 shows both of these arrangements. 

Fig. 3. Rough layout sketch (/) the two fined heaters F-1 and F-2 are located together but are separated from the other equipment with a subpipeway connecting the process area to the heater area (2) the reboiler E-2 is located adjacent to its column, T-1. The preheat exchanger E-4 is located adjacent to tower T-3 (J) the elevated overhead condenser E-3 is located next to the overhead accumulator V-1. Also, the ain condenser EE-3 is located adjacent to its overhead accumulator V-2 (4) the rest of the ain coolers (EE-1—3, -5) are grouped together ia a common fan stmcture (5) all equipment and related piping is routed to and from the existing piperack saving the addition of a new piperack (6) all pumps (P-1—P-6) are located ia a row under the piperack, and each...

A more complex unit is shown in Fig. 13-24, which is a schematic diagram of a distillation column with one feed, a total condenser, and a partial reboiler. Dotted hnes encircle the six connected elements (or units) that constitute the distillation operation. The variables N, that must be considered in the analysis of the entire process are just the sum of the Nfs for these six elements since here Nr = 0. Using Table 13-5,... 

Sample draw-off connections, usually for liquid from the trays, but some top (overhead) and reboiler vapor as well as liquid can be very useful. 

Figure 10-105. Nozzle connections for vertical thermosiphon reboilers.

After the proper pressure halance-heat transfer relationships are established, the calculations are summarized in connection with other heat flow resistances in the reboiler. 

Note If a tee connection to spare reboiler is used, add tee to pipe list. 

When laying out the diagram, it is only necessary to show the relative elevation of the process connections to the equipment where these affect the process operation for example, the net positive suction head (NPSH) of pumps, barometric legs, syphons and the operation of thermosyphon reboilers. 

Make a preliminary mechanical design for the vertical thermosyphon reboiler for which the thermal design was done as Example 12.9 in Chapter 12. The inlet liquid nozzle and the steam connections will be 50 mm inside diameter. Flat plate end closures will be used on both headers. The reboiler will be hung from four bracket supports, positioned 0.5 m down from the top tube plate. The shell and tubes will be of semi-killed carbon steel. 

One important feature of Fig. 8.6 is the condensate drum balance line. Note, that this line is connected below the channel head pass partition baffle. This ensures that the pressure in the channel head, below the pass partition baffle, and the pressure in the condensate drum, are the same. If these two pressures are not identical, then the level in the condensate drum cannot represent the level in the channel head. For this reason, never connect the condensate drum vapor space to either the steam supply line or the top vent of the reboiler s channel head. 

Estimation of column costs for preliminary process evaluations requires consideration not only of the basic type of internals but also of their effect on overall system cost. For a distillation system, for example, the overall system can include the vessel (column), attendant structures, supports, and foundations auxiliaries such as reboiler, condenser, feed neater, and control instruments and connecting piping. The choice of internals influences all these costs, but other factors influence them as well. A complete optimization of the system requires a full-process simulation model that can cover all pertinent variables influencing economics. 

S4, connected to S2 by a recycle, but dynamically faster. Thus, supplementary inputs are D4-distillate flow rate, and Q4-reboiler duty. A major disturbance of the material balance can be simulated by a step variation in an external EDC feed. A second significant disturbance is the amount of impurity I3 introduced in the plant. 

There are many other possible ternary column systems that have different interconnecting streams between the columns. For example, if we eliminate only the reboiler (or only the condenser) from the prefractionator column in Fig. 13-67a, we obtain a partially thermally coupled system [Agrawal and Fidkowski, AIChE ]., 45, 485 (1999), U.S. Patent 5,970,742]. In other instances, one may significantly increase the thermodynamic efficiency of the direct split and the indirect split if a portion of the interconnecting stream is vaporized and fed to the second column below the liquid connection [Agrawal and Fidkowski, Ind. Eng. Chem. Res., 38, 2065 (1999)]. 

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