【2026 Column Equipment】Piping design of columns – Orientation of openings
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The main factors affecting the orientation of the tower opening are: nozzle function and tower internals. Based on the internal components, towers are divided into plate towers and packed towers; among these, packed towers have relatively fewer nozzles and simpler openings. The plate tower will be used as an example here.
1. Opening of manholes or manual access panels: Manholes or manual access panels should be located at a unified position on the operation side. When multiple towers are equipped with a joint platform, comprehensive consideration should be given. Manholes shall not be located in the position of the downcomer. A single overflow tray allows for the installation of manholes in the tower wall above any tray layer, whereas a double overflow tray has manholes in the tower wall above the trays equipped with intermediate downcomers, at intervals of one tray layer.
2. Installation of pipe nozzles: A. In principle, the nozzles for each side stream and for instrumentation in the fractionation tower should be installed on the operating side of the tower; nozzles that do not require flange connections can be installed on the pipeline side. The oil and gas pipeline at the top of the tower is generally located in the center of the roof cover.
The positions of the inlet nozzles for single and double overflow tower tops are shown in the figure; those without internal connections should be located within the isolated area of the liquid receiving tray (with anti-scour baffles installed), while the range of positions for nozzles with internal connections is wider (the internal connections must extend into the liquid receiving tray).
B. The liquid feed inlet and the mid-stage return inlet are generally inserted outside the downcomer, as close as possible to the upper tray, as shown in the figure below.
Oil and gas inlet is generally parallel to the downcomer and located near the upper tray, in line with (b)(d) for the middle section and liquid feed.
C. The extraction nozzles of a single overflow tray can be located within the lengthwise range of the liquid receiving tray; generally, however, the nozzles should be placed on the center line of the vertical downcomer. As shown in Figure (a) below. The dual-overflow tray should be installed on the end face of the liquid receiving tank, below the central downcomer; it can be provided with one nozzle or multiple nozzles, and its position is on the center line parallel to the downcomer, as shown in Figure (b). Additionally, an extraction pipe can be installed at the bottom of the liquid receiving tank beneath the intermediate downcomer; the nozzle of this extraction pipe can be positioned at any angle on the operational side, as shown in figure (c).
D. The positions of the reboiler return nozzles and the steam inlet nozzles should be placed on the tower centerline parallel to the liquid receiving tray, as shown in Figures (a) and (b) below.