5 replies to this topic

[Rahimzadeh]

Dears:

 In our plant the depropanizer tower reboiler level is very low in normal operation.

please tell us possible solution?

The tower has valve seive tray ,we plan rduce the weir height of lowest tray , it can solve the problem

 

Best Regards

 

M.R.Rahimzadeh

[Afshin445]

Dear Mr. Rahimzadeh

 

What type of reboiler you are using? Is it kettel or thermoshyphon type?

How rebolier liquid level is controlled? Is it with wier,or different method?

A sketch and more detail about reboiler can be helpful.

 

Afshin

Edited by Afshin, 02 March 2013 - 02:45 AM.

[Bobby Strain]

What is the problem?

Bobby

[Rahimzadeh]

Dears:

Problem is during normal operation the reboiler level goes down .

Reboiler is kettel type , it ihas wier .

reboiler has has high and low level alarm

 

Best Regard

M.R.Rahimzadeh

[fallah]

^{Mr Rahimzadeh,}

 

^{Please upload a simple sketch of the system...}

 

^{Also following matters should be clarified:}

^{-Please specify if H and L level alarms are directly on reboiler or on downstream piping pot (if there is)}

^{-Please specify if the problem has had after the first start up or is a new one a while after normal operation without this problem}

 

^{Anyway appears the problem has been arised due to a wrong hydraulic design of reboiler respect to the tower...}

[Robert Montoya]

Hi;

The analysis for such problems can come from the following sources:
- Check the inlet temperature to the tower, when the inlet temperature decreases requires greater heat flow in the reboiler.
- Check the input and output temperature of the heating medium, usually occur when the inlet temperature is below the normal value requires a greater amount of flow by design often can not be provided.
- Check the composition of the feed inlet, whether there is a heavy increase in the required higher quantity of heat at the bottom of the tower.
- The level for this type reboiler heat exchanger varies in the same way as does the level of the tower.

Generally the level in the reboiler is cascaded with the output temperature of the heating medium or the flow and can also be shared with the loop inlet temperature to the tower. Other words the low level goes hand in hand with the profile of temperature and pressure in the tower that would help give the problem of low level in the reboiler.
As a last option suggests you check reboiler design: heat transfer area, level and distillation tower reboiler level.
It is important to do this analysis as soon as possible to prevent damage to the pipes that are not being covered by the hydrocarbon.