Special Tray Design Features
Mapesa personnel are knowledgeable from both a design and manufacturing standpoint of virtually all fractionating tray enhancement features. Many of these special features can often greatly improve overall tray performance. Not only do we offer these features upon customer request, but in many cases, we suggest the use of them in instances where our experience indicates the benefits.
Some of these special features and explanations of their uses are as follows:
Swept-back weirs are side outlet weirs which are multichordal in lieu of a single chord design. This design is sometimes utilized for side flow trays of a multipass design to balance liquid loads or sometimes for a single pass tray to reduce the effective liquid height on the tray by decreasing the volume of liquid per unit length which flows over the outlet weir.
Splash baffles are used to maximize the liquid retention time on trays used in very low liquid rate services. These baffles are located adjacent and parallel to the outlet weir and clear the tray deck and the outlet weir by 1/2" to 1" whereby exiting liquid is forced to flow under the baffle prior to flowing over the top of the outlet weir.
Picket-fence baffles are used to decrease effective weir length. They are often utilized in cases where the liquid flow over the weir would otherwise be less than one gpm per inch. Picket-fence baffles can increase the effective liquid height on the bubbling (active) area and reduce "blowing". These baffles (which either attach or can be formed integrally with the outlet weir) are uniformly spaced to allow evenly distributed flow into the downcomer. They can be used in conjunction with splash baffles when both features are needed.
Anti-jump downcomer baffles are used on multipass trays for center and off-center downcomers when needed to prevent liquid which is flowing across the tray from blowing or jumping over the downcomer and onto the opposing flow path. When the width of the downcomer is small and the loading is high, these are particularly advantageous.
Sloped downcomers with recessed inlet sumps can be effectively utilized in heavy liquid loaded services that would otherwise be prone to downcomer flooding.
Cartridge trays (which are shop prefabricated into bundles of 4 or 5 trays each, equipped with enveloped downcomers, peripheral packing glands and spacer rods) are a viable approach to the installation and removability of trays for towers which are too small for workmen passage.
In addition to the special features listed above, Mapesa has experience in the utilization of many other tray enhancement features and is open to consideration of the use or development of any new ones that could improve performance in any way.