reboiler in the column 3

[skvishwa]

hi all,
This question referes to a thread i saw some time back about the reboiler "slip flow",because of the low velocity and all.....
I am facing a similar problem in a column reboiler.The system includes a vertical thermosyphen reboiler in a column .The column is mainly a stripper that is being for stripping the Hydrogen Sulphide and light hydrocarbon from the Wild naphtha generatd from the Diesel Hydrotreater.
The problem is very peculiar.The comlumn reboiler does not function when the feed flow is below a particular value and starts to function after reaching a particular column feed flow,but after running normal for some time again it slowly starts to behave abnormally.
The column top temperature, reboiler inlet temp,bottom temp,all come down.But the reboiler outlet tempearture remains same.this indicates that the thermosyphen is not getting stabilsed and the flow thru the reboiler is decreasing .After the stable operation for some time the reboiler thermosyphen gets broken.
Any solution?
Santosh

 

[alirahmani2]

For dimethylformamide(DMF)recovery use two packed(column1:K1 ) and valve tray(column 2: K2) columns, feed(40 H2O/60 DMF)SEND TO K1 and bottom outlet of k1 about 25%H2O and 75%DMF send to evaporator and vapour of DMF70%/H2O 30% feed to k2 the bottom of this column is 99.95% DMF AND THE TOP OUTLET OF K2 is 99.8% H2O and o.1% to 0.2% DMF as steam send to shell side of reboiler of k1 as a source of heat the main problem related to this reboiler capacity the outlet of shell side of this reboiler is vapour and lquid and so k2 pressurised and reduce the recovery effic. the capacity of this reboiler in data sheet is enough but realy in plant we have problem tube and shell side of this reboiler are completly clean what is your idea about this problem?