Why are multiple feed inlets sometimes designed for distillation towers?
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Why are there valves on both feed inlets in some designs? Some of them don’t have valves/ Could everyone please help?
To facilitate better heat transfer, a medium with a higher boiling point in the gas phase is condensed, while those with a lower boiling point in the liquid phase are vaporized, thereby achieving the purpose of distillation
Where valves are available, the feed composition varies (i.e., there is a spare port); the feed height on the tray is adjusted accordingly based on these compositional changes to ensure the best control parameters. The absence of valves usually means simultaneous feeding, and it may be two feed streams with different compositions; the purpose is the same, which is to ensure that, through proper tower design, the material balance on each tray remains as consistent as possible.
What you mean is that for a certain raw material, there are 2 to 3 feed inlets on the tower. This situation often occurs in units related to oil refining; due to changes in the composition, there are multiple feed inlets.
The purpose is to adjust the distillation section and the stripping section based on the feed rate and the distillation conditions; generally, when the feed rate is high, the distillation section should be increased accordingly, and vice versa. It is not necessary to use both feed inlets at the same time
Adjust the position of the feed inlet according to the desired separation effect, in order to achieve the required level of separation.
This also relates to the appropriate number of feed trays; it is better to choose a feed point with a composition similar to that on the theoretical tray
The valve can be switched as necessary to reduce the impact of feed variations on the distillation efficiency. Without valves, feeding should occur simultaneously; aren’t the two feed streams the same?
This is to achieve a better separation effect; some systems have multiple feed inlets placed above and below the theoretical feed inlet, while some distillation towers have 3 feed inlets at the top of the tower.
This is related to the operation of the process; feed at different locations affects the gas and liquid load on the tower as well as its efficiency.