Reboilers, sizing

For the case here, the computer program has calculated the reboiler sizing Reboiler Size Required... 

For a given reboiler size Bo, the following constraints apply ... 

Condenser and reboiler sizes depend on Q, and Qr. These values can be determined from external mass and energy balances around the column. Equations f3-141 and (3-16) allow us to calculate and Qr for columns with a sin e feed. is proportional to (1 + L/D)F and is proportional to F and increases... 

Reboiler return line sized too small. Poor separation limited capacity. Unstable operation. Expansion design error. 

A pull-through, floating head, kettle-type reboiler having stationary head integral with the tubesheet, 23-in. port diameter and 37-in. inside shell diameter with tubes 16 ft long is denoted as SIZE 23/37-192 TYPE CKT,... 

The previous discussion focused on the use of indirect fired heaters as line heaters to provide the necessary heat to avoid hydrate formation at wellstream chokes. Indirect fired heaters have many other potential uses in production facilities. For example, indirect fired heaters can be used to provide heat to emulsions prior to treating, as reboilers on distillation towers, and to heat liquids that are circulated to several heat users. The sizing of indirect fired heaters for these uses relies on the same principles and techniques discussed for wellstream line heaters. 

For most field gas units it is not necessary to specify a stripper size. Vendors have standard design amine circulation packages for a given amine circulation rate, acid-gas loading, and reboiler. These concepts can be used in a preliminary check of the vendor s design. However, lor detailed design and specification of large units, a process simulation computer model should be used. 

Table 8-2 can be used for an initial approximation of reboiler duties, If the reboiler is heated with a fire tube, the fire tube should be sized for a maximum flux rate of 8,000 Btu/hr-ft . 

Voives Installed if Reboiler to be Removed for Cleaning, Should be Full Opening Line Size. 

For a given fluid condition and assumed size of reboiler, evaluate physical property factor c )i from Figure 10-107A and physical property factor from Figure 10-107B. 

For services in which fouling is high or in which downtime cannot be tolerated, two reboilers may be installed on the same distillation column. These reboilers may each be half sized so that downtime will be limited to a half-capacity operation each may be two-thirds sized or each may be a full 100% spare. The latter is, of course, the most expensive from an equipment investment standpoint but may pay for itself in uptime. 

Vertical Thermosiphon Reboiler Comparison Effect of Pressure Drop and Pipe Size on Selection... 

The tube lengths used for vertical thermosyphon reboilers vary from 1.83 m (6 ft) for vacuum service to 3.66 m (12 ft) for pressure operation. A good size for general applications is 2.44 m (8 ft) by 25 mm internal diameter. Larger tube diameters, up to 50 mm, are used for fouling systems. 

Reboilers for columns, using relatively small size direct-fired units. 

In sizing depressuring valves, it should be assumed that heater burners are shut-off, reboilers are shutdown, and normal flow in the vessel has ceased. Vapor depressuring valves should be designed such that the initial, instantaneous depressuring flow rates do not exceed the capacity of the closed pressure relief system and the flare. 

Purification of the reboiled caustic soda is important to remove sizes (raw-mercerization), dyes (mercerization of dyed materials), fibers, and impurities released from the fibers. Important techniques are filtration, centrifugation, flotation processes, and oxidative processes [29-31]. The application of membrane processes for reconcentration is limited to low concentrations of NaOH because of the insufficient chemical stability of the membranes. 

Because increasing the pressure raises boiling temperature, it also increases the differences between overhead condensing temperatures and the temperature of the cooling medium, but at the same time reduces differences between the bottom vaporization temperatures and the temperature of the heating medium. Consequently, the size required for the condenser is reduced and the size for the reboiler is increased as the pressure is raised [31]. 

In vacuum distillation, excessive pressure drop causes excessive bottom temperatures which, in turn, increase degradation, polymerization, coking, and fouling, and also loads up the column, vacuum system, and reboiler. In the suction of a compressor, excessive pressure drop increases the compressor size and energy usage. Such services attempt to minimize tray pressure drop. Methods for estimating pressure drops are similar for most conventional trays. The total pressure drop across a tray is given by... 

The prices shown for distillation columns are misleadingly low. Most of the cost of a conventional distillation column is associated with the reboiler, condenser, pumps, reflux drum, and internal trays or packing. Equipment costs can be ratioed by the 0.6 power with size to obtain rough prices for larger or smaller sizes. 

For single separation duty, Bernot et al. (1991) presented a method to estimate batch sizes, operating times, utility loads, costs, etc. for multicomponent batch distillation. The approach is similar to that of Diwekar et al. (1989) in the sense that a simple short cut technique is used to avoid integration of a full column model. Their simple column model assumes negligible holdup and equimolal overflow. The authors design and, for a predefined reflux or reboil ratio, minimise the total annual cost to produce a number of product fractions of specified purity from a multicomponent mixture. 

Reboiler and condenser size (heat transfer areas). 

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