Plot space

The vertical position is preferred if the plot space is tight. Horizontal vessels are easier to support and are preferred when large Hquid surge volumes are required. The Hquid level displacement height for a unit volume is much less for a horizontal vessel than for a vertical vessel, which makes the control range shorter than for a vertical vessel. The displacement height per unit volume is only approximately linear on horizontal vessel when the level is near the center line, however. This can be a problem if the normal Hquid level is too low or too high and the instniments are not tuned for quick response. 

Fig. 1.5 Simulated NMR data from a cylindrical object projected onto a direction perpendicular to the cylinder axis. Left 128 steps of kx were applied and the succession of FIDs are plotted /(-space is covered sufficiently well, i.e., the signal has decayed to zero at the largest values of kx. The Fourier transform of the series of FIDs (taken from the first points or from the...

A design consideration for an environmental application of TSS technology is location. In a PRT unit, the TSS is always located in a hot flue gas position. However, a cold flue gas position could be used for environmental applications. Depending upon the pressure control scheme, the TSS can also be located at high pressure before the flue gas slide valve and orifice chamber. This offers significant cost savings, lower material cost, and requires less plot space. On two ERA consent decree applications, this benefit was 40% lower capital cost. 

Vertical separators eire used when there is small liquid load, limited plot space, or where ease of level control is desired. 

Kettle reboilers. Kettle reboilers have low heat transfer rates, a high fouling tendency, a high plot space consumption, and are expensive. They are therefore not very popular in distillation practice. Situations in which they are preferred are ... 

Forced-circulation reboilers are similar to vertical thermosiphon reboilers, but do not depend on the natural thermosiphon action, and commonly operate at high circulation rates. The pump replaces the level in the reboiler sump as the driving force that sets rehoiler circulation. Heat transfer is mainly by sensible heat, often followed hy nucleate boiling. Additional boiling occurs when the heated mixture is flashed at the reboiler outlet. Forced-circulation reboilers may be installed horizontally or vertically horizontal units are often easier to clean, but consume more plot space. 

An economic L/D ratio is between 1 and 10. L/D ratios greater than 10 may produce the lowest surface-area-to-volume ratio but should be considered impractical for most applications. Obviously plot space is also a consideration in ultimate cost. In general, the higher the pressure the larger the ratio, and the lower the pressure the lower the ratio. As previously stated, the optimum L/D ratio for an atmospheric drum is 1. Average pressure vessels will range between 3 and 5. 

Conservation of plot space in contrast with a separate heat exchanger. 

Design constraints There are generally more constraints due to re-use and modifications of the existing plant equipment within limited plot space and project execution time Fewer design options and constraints... 

Plot space Plot space is limited and constrained by maintenance access, fire, safety and emergency handling requirements Sufficient plot space is generally available... 

Space constraint Require elevated platforms for surface condensers, (semi-) barometric drain pipes for condensate removal, and separators for separating foul water and oil. Non-barometric installation is possible by combining SJEs and LRVPs Surface condensers and elevated structures are not required. Instead, they require closed-loop liquid coolers for reducing water consumption and gas-liquid-liquid separators. They are compact and require less plot space... 

With increased market demand, the refinery wants to make four naphtha products from two naphtha products. If using the conventional design, two new columns are required with a direct sequence of three columns to make four naphtha products as shown in Figure 11.16. However, the showstopper for this design is the plot space for installing two new columns. The question then becomes Are there any advanced separation technologies available that can resolve the plot space issue ... 

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