How to caculate air flowrate required for prevent from vacuum forming? 2

[chain]

Compressed air will be inputted into a vessel after sterilization in order to prevent vacuum forming in the vessel. So, how to caculate and determine the air flowrate to meet the demand.

Appreciate your help so much!

 

[quark]

Generally these vessels are fitted with vent filters, which allow filtered (0.2 micron) air to go into the tank. How do you vent out the steam in the tank after sterilization? Are you allowing it to condense totally?

Regards,


Believe it or not : Though human body is made up of intricate and subtle mechanism, it is very poor in energy conversion. The maximum efficiency is 20% during cycling. During under water swimming it is just 4%.

 

[chain]

Thanks for your reply. After sterilizing of the vessel, we will open the vessel vent valve(pulse the valve), also all condensate will be drained.

During the above process, we will input clean air to the vessel to compensate the depressurization. how to determine the flowrate, which is related with steam condensate rate ?

Regards

 

[quark]

That is quite easy once you know condensate mass flow rate. Check the specific volume of steam at the operating temperature from steam tables. For example, at 121⁰C the specific volume of steam is 0.841 M³/Kg (at a pressure of 2.11 bar a). If your condensate flow rate is, say, 30Kg/Hr then you are evacuating the chamber at a rate of 30 x 0.841 = 25.23 M³/Hr. So that should be the compensation for reduced volume.

If you provide atleast half the flow rate, your chamber will be at atmospheric pressure. (the 25.23M³/Hr flow rate will maintain the chamber at sterilization pressure)

Regards,


Believe it or not : Though human body is made up of intricate and subtle mechanism, it is very poor in energy conversion. The maximum efficiency is 20% during cycling. During under water swimming it is just 4%.

 

[chain]

If you provide atleast half the flow rate, your chamber will be at atmospheric pressure. (the 25.23M3/Hr flow rate will maintain the chamber at sterilization pressure)

How to figure out the condensate mass flow rate ? Is there any general reference?

If the condensate process is going while cooling the vessel via jacket, how I can deal with the condensate mass flow rate ? I ever used heat transfer formula to find the answer. However, the calculation result is not practical.

 

[dtreacy]

The best option is the 0.2 micron absolute hydrophobic vent filter as previously stated by quark. If sterilisation is critical ensure that the vent filter can be integirty tested in-situ to ensure that it provides full protection.
Also heat tracing on the vent filter is essential as condensation forming on the filter from steam can cause it to clog and fail.
Safety is essential fit a suitable rupture disc and breach sensor.

Regards

 

[Jigneshpadia2002]

I feel that you still want to know the the requirement of the air to be feed into the tank. Coz that is where vent filter sizing will come into the picture! Do you guys agree???

 

[quark]

That's right. See the sample calculation on my 25th Oct' post.