7 replies to this topic

[tpplo]

Dear Sir

              I get a problem with running RADFRAC column when i using design spec and setting mass purity and reflux ratio at the same condition before using design spec which not getting error but when i using design spec it get error as the picture below how can i do sir

 

 

 

 

 

 

**  ERROR

      RADFRAC NOT CONVERGED IN 200 OUTSIDE LOOP ITERATIONS.

 

 

[Pilesar]

There is not enough information provided to know for sure. I suspect the simulation is over specified. If the column converges before the design spec, then adding another spec requires another variable to be free to change.

[tpplo]

There is not enough information provided to know for sure. I suspect the simulation is over specified. If the column converges before the design spec, then adding another spec requires another variable to be free to change.

 

Thank you for your advice sir,I simulate about change ethanol to acetone after RSTOIC the products are acetone, acetaldehyde,CO2,H2,ethylene and excess ethanol and water after reactor  the stream deliverd to flash column to separate gas-liquid phase after that deliver to distillation (Radfrac) to separate acetaldehyde   the results from RADFRAC column are mass fraction of acetaldehyde is 0.9 and reflux ratio(mole) is 3.05 the final column which i can separate acetone the bottom stram of this column will be the recycle stream to feed preparation for this reason i gonna use design spec for all my radfrac and vary reflux ratio and distillate rate Or i can vary another variable sir Please advice me
Thank you so much sir to reply and recommend

[breizh]

Hi,

Can you draw a sketch of your set up (Process flow diagram) and post it, it will save time for people to understand?

In addition, let you provide information about the steams (Composition, flow, temperature, pressure).

This should help you and others willing to help.

Good luck

Breizh 

[tpplo]

Hi,

Can you draw a sketch of your set up (Process flow diagram) and post it, it will save time for people to understand?

In addition, let you provide information about the steams (Composition, flow, temperature, pressure).

This should help you and others willing to help.

Good luck

Breizh 

Thank you sir for your recommend
Here's the PFD

https://docs.google....dit?usp=sharing

The inlet stream(stream 12) mass fraction ofis 

ETHANOL 0.047

WATER                  0.74

ACETONE              0.187

CO2 0.0009

H2 2.38E-06

ACETA-01(Acetaldehyde) 0.024

ETHYLENE 7.52E-06

The outlet stream(stream 13) mass fraction  is

ETHANOL 3.5E-08

WATER 0.06

ACETONE 0.0052

CO2 0.033

H2 8.8E-05

ACETA-01(Acetaldehyde) 0.902

ETHYLENE 0.0003

 

I'm using the same condition(reflux ratio) in sensitivity is getting result but in design spec is getting error 

**  ERROR

      RADFRAC NOT CONVERGED IN 200 OUTSIDE LOOP ITERATIONS.

How can i do

[breizh]

Hi,

I was expecting someone knowledgeable about the software to support you, anyway you may be able to increase the number of iterations and/or break the loops performing calculation manually to reach an acceptable solution which could be the initialization point for the automatic calculation after reestablishing the loops.

Sorry I cannot offer more, waiting for others to support.

Sawasdee krub, chokdee .

Breizh

[tpplo]

Hi,

I was expecting someone knowledgeable about the software to support you, anyway you may be able to increase the number of iterations and/or break the loops performing calculation manually to reach an acceptable solution which could be the initialization point for the automatic calculation after reestablishing the loops.

Sorry I cannot offer more, waiting for others to support.

Sawasdee krub, chokdee .

Breizh

 

Thank you so much sir

[Pilesar]

Without knowing your specs with their variables, there is not much info to go by. Each spec should match with its own variable. The variable has to have freedom to adjust without violating mass balance constraints. I still suspect the problem is over specified somewhere.