4 replies to this topic

[processengeng]

Hi everyone. Currently I am asked to study a fixed cone roof tank which is used to store a pure chemical at 80 degC. This chemical vapor cannot be discharged directly to atmosphere, so a scrubber is needed to be installed at vapor outlet to scrub the chemical vapor to a certain ppm. This tank is blanketed with nitrogen. Anyone can advise me how to calculate the vapor concentration and the max flow rate to the scrubber?
The following are some conditions:
1. The tank operates at atmosphere
2. The chemical will be unloaded from a truck via a pump-A to this tank. And a pump-B is installed to pump out the chemical to a reactor.

Thank you in advance!

[fallah]

Hi,

 

Try using API 2000 to specify the total out-breathing flow rate as maximum outgoing flow rate toward the scrubber. For estimation of vapor concentration you need to know, at least, the liquid boiling point at tank's design pressure... 

[breizh]

Hi ,

To support your work ,

Good luck

Breizh

[processengeng]

Dear fallah and breizh,

Thank you very much for your fast reply and information. I got some ideas to calculate the flow rate.  Could you please advise more about the vapor concentration?

How do I calculate the concentration if I know the boiling point at the design pressure?

I am planning to calculate it in the following way, but not very sure if it is correct:

 

1. Get the chemical vapor pressure @ 80 degC
2. Then I can calculate the molar fraction of chemical vapor and nitrogen respectively (since the tank operates at atmospheric pressure).

 

Please correct me if the above steps are wrong.
Thank you in advance.

[fallah]

 

How do I calculate the concentration if I know the boiling point at the design pressure?

I am planning to calculate it in the following way, but not very sure if it is correct:

 

1. Get the chemical vapor pressure @ 80 degC
2. Then I can calculate the molar fraction of chemical vapor and nitrogen respectively (since the tank operates at atmospheric pressure).

 

Please correct me if the above steps are wrong.
 

 

Hi,

 

If it's supposed the Dalton Law is applicable to the case, the way you described can be terminated to a good estimation...