Tray support ring

Leaving tray support rings in towers revamped with packed beds. Poor separation. Premature flooding. Installation error. There are too many examples of this for us to continue to make this one. If you are not confident enough to remove the tray support rings, don t pack the tower. 

The common reason for out-of-levelness of trays is sagging of the tray decks. Sags are caused by pressure surges and sloppy installation. Sometimes, the tray support rings might not be installed level or the tower itself might be out-of-plumb (meaning the tower itself may not be truly vertical). 

Chimney tray Tray support ring sections [Pg.108]

In small columns, packing supports often rest on a tray support ring. 

Strigle (386) states that when repacking with random packings, tray support rings need only be removed when they occupy more than 10 percent of the column cross-sectional area. Accordingly, the maximum acceptable support ring width depends on column diameter as follows (386). 

One case has been reported (346) where random packings performed well in a 13.5-ft-diameter column even though the tray support rings were not removed. 

If the old tray support rings and downcomer support bars are to be removed, it is best to cut them approximately % to V2 in from the shell (74, 168, 274, 299a, 336, 386). Complete removal (i.e. grinding flush) is time consuming, expensive, and rarely justified. 

Major support beams should be installed first. The top of the beam should be flush with the tray support rings. Shims are often added to accomplish levelness. 

Tray Support Ring Tray Support Beam Typical Bubble Cap Tray Seal Pan... 

Out of level of Tray Support Rings See Tolerances for Trays ... 

Tolerances for Trays, Tray Support Rings and Downcomers... 

The working elevation of a tray support ring shall be die elevation specified on the outline drawing. It shall be a level plane parallel to the MRL. 

The distance from the MRL to the working elevation of any tray support ring shall be within + - 1/4 in. (6mm) of the nominal distance. 

The highest and lowest points of a tray support ring, measured adjacent to the vessel shell, shall not exceed the following deviations from the working elevations ... 

Tray support rings shall not have a waviness exceeding 1/16 in. (1.5mm) for any 1 foot (300mm) of circumferential length. 

Coker fractionators are subject to damaging pressure surges due to accidental flashing of water. The pressure surges results in the tray decks "ripping" away from the tray support rings. 

Why, you might ask, is it necessary to initially wash a badly fouled tower from the top down A tray plugged with mud will severely restrict the flow of water. The resulting pressure drop may be sustained by the tray when it is pressed down onto the tray support ring but the same pressure drop can rip the tray from its support ring when applied from the bottom of the tray. 

This credit for stiffness by the tray-support rings results in a A value of 90.0 compared to the previou.s computed value of 85.5 ft. The next step is to check the shell for empty condition, no trays, no insulation, no pressure, vapor line in place, only wind load acting. Credit may be taken for eoiTosion all wanc( under erection conditions. 

In summary, the 20 trays can be replaced with a 31.5-ft deep bed of 2 Hy-Pak packing using only 16 tray spaces to facilitate optimum use of the existing tray support rings. This revamped column will accommodate a 35% increase in gas and liquid flow rates while providing at least the same CO2 removal efficiency as the present trays. 

The tray support rings are typically 3 inches wide. That means there are no holes in the tray decks about 4 inches, from the vessel wall. Liquid can bypass the bubbling vapor through these gaps and reduce tray efficiency. 1 have two ways of dealing with these gaps ... 

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