DCU Feed tank

[Anonymous]

Hi
 
What is the typical feeding system of onr DCU ? In our case we have storage tank of our feed in the off site area. This tanks receive VR (vaccum residue) from the vaccum tower and by gravity feed the pumps on the unit (DCU). The advantage of this system is that if have any problem on the distillation unit, the feed tanks provide enough residence time in order do not stop the DCU. The another point is the cost of the inventory. We are think to replace the tanks by feed vessell in the unit (on site).
What would be the residence time of this vessell ? Is it common to use a feed vessell in the unit (DCU) in order to receive the charge straight from the distillation unit ?
 
Thanks

[Lucibar Davalillo]

As far i know, no many cokers have a feed tk; last coker i was had one as part of the unit; it was designed to allow about 24 hr recovery for, either coker or vacuum unit short trips; tk level was allowed to increase from 50 to 80% in the case of coker shutdown; or, from 50 to 20% for the case of vacuum units shutdown. The tk was provided with 2-60% capacity pumps; about 70-80% of total vacuum bottoms was directly fed to the coker and the remaining was going thru the TK via coker feed.   
 
Regarding location, the preference should be to be closer to the coker unit as possible and letting coker to control inventory.
 
it is highly important providing the tk with temperature indicators to be used as cross-check for level readings; 2 radar were used, one for control and one for indication.

[Author]

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