3 replies to this topic

[Niha]

Dear All

Hi

I am a new member in Cheresource.

This is my first Topic in forums.

 

I am starting to do process basic design of a Propane-Butane refrigeration unit.

In the first I have two alternatives for simulation and study. 1- close loop 2- open loop.

I want to simulate a close loop C3-C4 refrigeration facilities and storage.

commonly propane and butane chillers are kettel type. I have some question now:

 

1- why kettle type will be selected for these units? can we check other type of heat exchangers for these chillers such as plate heat exchanger, or not ? for example one complex plate heat exchanger instead of 3 propane chiller.

 

2- how can I add a kettle type heat exchanger in Hysys flow sheet ? K type for shell side is not available in aspen hysys exchangers. It is existent in EDR (Exchanger design and rating) but in Aspen Hysys area it is not available (kettle type are existent just in column area).

 

3- how can I check and compare the results in two simulations ? how can I select optimum process.

 

Best Regards

 

NIHA

 

[Bobby Strain]

You should first put a model together and get it working. Then you are likely to learn much and answer many of the questions that you pose. Start simple with the things you know.

 

Bobby

[Niha]

Thanks Bobby Strain

 

Ok , I know that I must to check both of the models , but in the first I want to know , how can I add a kettle type heat exchanger in Hysys flow sheet ? Please help me if any body knows.

 

Best Regards

 

Niha

[Neelakantan]

may be it is too delayed response;

I am also simulating a gas plant having a glycol dehydration, regeneration, dewpoint control, condensate stabilization and refrigeration;

 

one of my juniors posed the same question; per se no kettle type unit operation is present in hysys pallete;  now as you have noted and mentioned in OP kettle type reboiler is shown for the column (the reason being it is a separate stage as there is vap/liquid separation and not for heat transfer)

 

the next question is where you want such an operation:

 

1) typically in our case the stabilizer column bottom reboiler is a kettle type (BKU or AKS); for the last few years right from hysys 3.2, I have been using an exchanger followed by a separator with a matching recycle (which is set to ignore initially and later brought in for convergence) to "simulate" a reboiler with vapour liquid separation;  this is just a personal way of doing things and really you don't require to do that.

 

2) the second case you are looking at is probably the gas chiller?  here you definitely don't need vap-liquid separation in the heat exchanger as there is normally a cold separator in the gas cooling train; (Costain has a coldbox with internal separators where a mimicking simulation is to divide the exchanger in series with separators in between;) as a process engineer you don't require to do that; equipment manufacturer will do that

 

if you are in projects side of a process group then you may be sizing the exchanger and you will be using either EDR or HTRI for the exchanger; at which point you can select the type of the exchanger; remember HTRI and EDR do a flash and remove the gas from exchanger section while calculating heat exchange; so it is always prudent to have a look at these results and see whether suitable margin is provided

 

hope I am able to answer your question

 

best regards

neelakantan

Edited by Neelakantan, 13 April 2014 - 11:52 AM.