6 replies to this topic

[CheAmine]

Hello.

 

We would like to perform back puffing for one of our plate fin heat exchangers to remove debris and for that we  would like to use PVC sheets instead of bursting disks since it is cheaper.

 

I would like to know how to calculate the thickness and number of PVC sheets that are required to be used at a time. Note that Nitrogen gas will be used, hence the bursting pressure will be approximately 7 barg. Moreover, the nozzle size is 18 inch.

 

In addition to that I would like to know whether nitrogen gas at a pressure of 7 barg is sufficient to provide the required velocity to clean the exchanger from the debris during the bursting of the PVC sheets.

 

Thanks

 

 

[breizh]

CheAmine,

 

It does not like very safe to me ! What about chemical cleaning ? did you check for this option ?

 

Breizh

[CheAmine]

Breizh,

 

We are not expecting any sticky hydrocarbon material since the process is dry gas, instead we are expecting molecular sieves material  and debris due to strainer damage located upstream of the heat exchanger, that's why we don't think chemical cleaning is required. Back puffing has been performed in many other exchangers as well in a safe manner, moreover the heat exchanger manufacturer has approved this type of cleaning.

 

 

Regards,

[breizh]

Hi ,

In this case why don't you use water ?

 

My 2 cents

 

Breizh

[CheAmine]

Breizh

 

These are cold box exchangers in which it is not advised to have any traces of water in the system (after normalizing the system) since it will lead to hydrate formation and consequently plugging of exchanges and piping.

 

Amine

[manojkaila]

Dear Amine,

 

As per my experience normally I preferred bursting with first one sheet only and then increasing the no of sheet with increasing the air / Nitrogen pressure. After few burst you will get clean gas and no external material then we can confirm that line is clean. For extra precaution you can do few more blasting. Take care for area safety.

 

Hope this will help.

 

Good luck

 

Manoj 

[CheAmine]

Manoj,

 

Thank you for your input. We will be doing the same starting with one plastic sheet having a thickness of 1 mm and increasing the number of sheets so that to achieve the required bursting pressure.

 

Regards,