7 replies to this topic

[Supriyo Mukherjee]

I am working with a methane gas purification unit.

The inlet gas composition is

 

CH4 = 55%.

 

CO2 = 45%

 

H2S  = 700 ppm(v)

 

Flow = 350 NM3/HR

 

Pressure = 1.2bar (A)

 

 

We are required to separate H2S and CO2 from the methane.

 

As H2S is in small amount and CO2 in very large quantity, I chose to absorb the CO2 by amine sweetening unit. 

 

I used MEA.

 

The problem I am facing is simulation shows fatal error in higher percentage of CO2 in feed.

 

Could anyone kindly help me out with this simulation.

 

I have tried to provide all information I have at this stage.

 

Regards,

 

 

[Neelakantan]

check the pressure? 1.2 bara?

regards

neelakantan

[RockDock]

Which simulator are you using? You will need to use ProMax for this.

[Padmakar Katre]

I am working with a methane gas purification unit.

The inlet gas composition is

 

CH4 = 55%.

 

CO2 = 45%

 

H2S  = 700 ppm(v)

 

Flow = 350 NM3/HR

 

Pressure = 1.2bar (A)

 

 

We are required to separate H2S and CO2 from the methane.

 

As H2S is in small amount and CO2 in very large quantity, I chose to absorb the CO2 by amine sweetening unit. 

 

I used MEA.

 

The problem I am facing is simulation shows fatal error in higher percentage of CO2 in feed.

 

Could anyone kindly help me out with this simulation.

 

I have tried to provide all information I have at this stage.

 

Regards,

 

 

Please tell us your exact role in this design? What is status of this unit? is it under conceptual stage, a working unit? What is absorber operating pressure and solvent details such as type and its operating conditions.

[Supriyo Mukherjee]

Dear All,

 

While I was researching a bit more on this unit. 

 

I ma sharing what I found out::

 

1. I used UNISIM

2. I used amine package.(limitation max 30% MeA)

 

 

3. I found out absorbtion tower pressure would be around 12 bar A. Neelkanthan you are right about the pressure.

 

As the percentage of CO2 is very large increase of pressure was neccessary for higher CO2 pick up by amine.

 

4. Th Pressure in the desorption tower was 1.5bar A.

 

5. MeA (solution with 28% MeA) :: used as absorbent and quantity is around 6.3 tons.

 

6. I am attaching the snapshot for sharing what I found out and also invite valuable comments .

 

7. Hello Padmakar seeing you after long time . Nice to c u. My role here is to fix the pressure temperature operating in this unit. Its in conceptual stage.

 

@Rockdock I am not having Promax simulator. But thanks for the advice.

 

Regards,

Attached Files

•  UniSimDesign-Print.pdf   18.63KB   36 downloads

[RockDock]

Sorry. Perhaps I could help you with a ProMax error, but I am unfamiliar with Unisim errors.

 

I don't think you can get reasonable results with Unisim for this process.

 

I created a rough ProMax model in about 5 min. I've attached the .pdf of it. Unisim is off by about 1000%. I would recommend using ProMax and the ProMax scenario tool to create your T and P operating envelope.

 

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

 

 

 

 

[RockDock]

One other thought I forgot to mention. You need to increase your circulation rate until you reach a rich loading of roughly 0.3. The current loading of 0.43 is too high for my comfort. It would likely cause accelerated corrosion.

[AlbertHahn]

Dear All,

 

While I was researching a bit more on this unit. 

 

I ma sharing what I found out::

 

1. I used UNISIM

2. I used amine package.(limitation max 30% MeA)

 

 

3. I found out absorbtion tower pressure would be around 12 bar A. Neelkanthan you are right about the pressure.

 

As the percentage of CO2 is very large increase of pressure was neccessary for higher CO2 pick up by amine.

 

4. Th Pressure in the desorption tower was 1.5bar A.

 

5. MeA (solution with 28% MeA) :: used as absorbent and quantity is around 6.3 tons.

 

6. I am attaching the snapshot for sharing what I found out and also invite valuable comments .

 

7. Hello Padmakar seeing you after long time . Nice to c u. My role here is to fix the pressure temperature operating in this unit. Its in conceptual stage.

 

@Rockdock I am not having Promax simulator. But thanks for the advice.

 

Regards

Without all the necessary information in place, it is hard to help.

From your information, I think there are two possibilities:

1. the pressure is too low, you can try 3000+ kpa

2. the gas rate is too high, which could cause flooding and in this case it won't have good absorption in reality, and simulation won't converge. you need to low down the gas rate and/or increase the solvent rate.