Why are herringbone baffles used in distillation towers?
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Why are herringbone baffles used in distillation towers?
It facilitates thorough mixing of the oil and gas moving upward with the heavier components (oil slurry) moving downward, thereby achieving heat exchange and the removal of catalyst from the oil and gas.
You can check out a picture to see what it looks like specifically
The feed temperature to the catalytic cracking distillation column is above 450 degrees, along with superheated oil and gas carrying catalyst dust, which is what sets it apart significantly from other distillation columns. The lower part of the catalytic fractionation tower contains an oil slurry desuperheating section. The slurry extracted from the bottom of the tower is returned to the tower after heat exchange and cooling, where it comes into counterflow contact with the rising oil and gas. On one hand, this quickly cools the oil and gas to prevent coking; on the other hand, it washes away the catalyst dust carried by the oil and gas. In the overheating section of the slurry, due to the high temperatures and the presence of catalyst dust, chevron baffles are generally used instead of trays.
Regarding this area for superheat removal and catalyst washing, in terms of superheat removal, both trays and packing can be used for gas-liquid heat transfer. However, due to the catalyst particles, ordinary trays and packing will become clogged. The baffles cause the liquid to flow down like a waterfall; there are V-shaped baffles and circular baffles. Ring baffles are used less frequently. Additionally, abroad, grid fillers are used; they result in lower pressure and better performance.
This is mainly due to the presence of a catalyst; using wedge baffles prevents blockage of the gas-liquid channels, whereas conventional floating valve trays or packing definitely will not work
The feed temperature to the catalytic cracking distillation column is above 450 degrees, along with superheated oil and gas carrying catalyst dust, which is what sets it apart significantly from other distillation columns. The lower part of the catalytic fractionation tower contains an oil slurry desuperheating section. The slurry extracted from the bottom of the tower is returned to the tower after heat exchange and cooling, where it comes into counterflow contact with the rising oil and gas. On one hand, this quickly cools the oil and gas to prevent coking; on the other hand, it washes away the catalyst dust carried by the oil and gas. In the overheating section of the slurry, due to the high temperatures and the presence of catalyst dust, chevron baffles are generally used instead of trays. If trays are used, they are prone to clogging.