Nt1310 Unit 3 Lab Report

The pitch is angled triangular, as this is a preferred method Sinnott (2005).
(Eq. 3.4 6) is used to calculate the number of holes per tray:

The number of holes per tray above feed stage is 25912, while below feed stage the number of holes is 24793.
The choice of hole diameter is usually about 5mm, but an increase in the size of the hole can be considered when fouling causes concern (Sinnott, 2005). The minimum hole size is about twice the size of plate thickness for stainless steel, in this case a hole diameter of 5mm is selected.

Calculations give a dry tray head of 9.54 mm per tray above feed and 9.68mm below feed stage. A dry tray pressure drop of 1.02 mbar right through the column.
The total tray pressure drop is the sum of the dry tray …show more content…
A total tray pressure drop of 133.23 Pa above feed stage and 164.29 Pa below feed stage
Downcomer backup flooding is influenced by downcomer geometry; among other factors. One function of the downcomer is to allow enough time for foaming liquid to deaerate. Sinnott (2005) suggests a minimum residence time of 3s to allow for deaerating of the liquid. (Eq. 3.4 16), given in Sinnott (2005) can be used to calculate the residence time of liquid in the downcomer:

Kister (1990) describes jet flooding as the accumulation of liquid droplets on the surface of the tray above due to increased vapour velocity. The point at which this occurs is at a maximum vapour velocity, known as the flooding …show more content…
Design pressure of the column should be able to handle the highest possible pressure differential likely to occur (Sinnott, 2005). The top pressure at the condenser is chosen as 0.46 bar and 0.75 bar at the bottom. The design pressure is set to 0.39 bar, which is 15% less than the maximum pressure differential; for safe measure. All equipment such as pumps, pipelines nozzles and any other associated column equipment is selected such that it is capable of handling a minimum pressure of 0.39 bar.
The design temperature, is chosen as a temperature higher than operating temperature to which all equipment and material subjected to associated with the column. The design temperature of the column is taken as the temperature at which design stress is evaluated including allowance for any uncertainties involved in predicting wall temperatures. The design stress (105 N/mm2) for the material (Stainless steel 316) of the column is evaluated at 300°C. Figure 3.4 16 and Figure 3.4 17 show the temperature profile of the column for operating reboiler duty 110% of operating reboiler duty and 90% of operating reboiler duty, whereby it can be seen that the temperature does not exceed 300°C. 300°C is chosen as the design temperature. All equipment such as pumps, pipelines nozzles and any other associated column equipment is selected such that it is capable of handling a maximum temperature

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