Q & A > Question Details
Why does the stripping steam trip close when there's a high level in tower?
28/01/2013 A: Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Generally Trays are inside the columns with clamps. Tray segments / sections are clamped on to the Tray support ring, tray sections and other support laterals with a 2.5" max contact area with the supports. When the trays are submerged in the liquid level all trays will be in semi-floating condtition hanging / anchored on to their clamps. any minor disturbance in the liquid will dislodge the trays. When the stripping steam (in vapor phase) enters the liquid phase (when liquid level is high) the two phase flow will have a bubbling effect (bubbles travel up to reach the top surface of liquid) on the trays and the weak sections will get dislodged. Imagine the water hammer energy when a two phase flow occur in the steam headers. That is nothing but steam (vapor) trying to exit the liquid phase.
28/01/2013 A: NS Murthy, Reliance Industries, ns.murthy@ril.com
It is basically to prevent blowing of tower internals (trays) when liquid level is above 100%.
27/01/2013 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
The bottom section of a typical coker fractionator contains a proprietary layout of pans, discs and donuts or side-to-side baffles, but no valve trays. So, the typical answer of avoiding an upset of tray sections does not exactly, but does directionally apply. Stripping steam is injected into a vapor space, intended to flow evenly through either horizontal or vertically flowing layers of liquid. When a high level covers the injection point of the steam, unnecessary agitation occurs, adding to the possibility of damage to the internals.