Air removal before thermal process

[sentenza]

Hello everyone, I need some advice on how to quickly remove air from a 400-liter tank before performing a thermal process. I was thinking of creating a separate tank where I can create a vacuum using a pump, and then use an automatic valve to connect the two tanks. My question is: how do I calculate the volume of the vacuum tank? What level of vacuum should I achieve inside it for efficient air removal from the system?
Thanks for help

 

[georgeverghese]

What do you have other than air in this tank ? And what temp is this at ?

 

[MintJulep]

"What do you have other than air in this tank ? "

OP has already implied that there are fruit and vegetables in the tank.

They'll likely outgas, complicating things further.

 

[shvet]

@sentenza
Aren't you afraid fruits&vegetables might explode during sudden vacuumizing? Are you ready to face with getting juice&pulp into a suction vacuum system?
Aren't you afraid the vessel might implode? Has it the wall thick enough to withstand the significant negative pressure?
Is it worth spending money on packaged vacuum system (food industry prefers dry screw pumps) and more expensive process system instead of tolerating imperfect peeling or enhancing the steaming procedure?

 

[Snickster]

I have came up with a possible solution thinking out the box. I think it may work to provide a quick vacuum and it is rather simple without any mechanical equipment except a small pump to fill the system. May need some tweaking and calculation/sanity check lol.

In the attached sketch water is filled up to top of elevated tank using a small GPM/Head pump from an atmospheric small volume storage/discharge tank while venting. Vent is closed and quarter turn valve such as butterfly is opened. Liquid level rapidly falls to evacuate the elevated tank until it reaches a height of 14.7 feet where tank is completely evacuated in about 4 seconds. 14.7 feet is level that P vacuum + Gamma*H/144 = 14.7 psia. Vent pipe and riser pipe are sized for maximum anticipated flowrate. Repeat steps for each subsequent cycle.

 

[sentenza]

I thank everyone for their active participation in the topic. I try to reply to some observations:

I just need 1 psi, a liquid ring vacuum pump can do it and accept carryover.
There is no risk of the skin bursting if the product is not heated first. We usual peel other products at lower steam pressure and 1 psia, but different machines.
Temperature could be a problem after heating cycle.
And yes I lack appreciation for exponential decay and other fundamentals.

 

[shvet]

I assume you meant water ring pump. Note that water vapor pressure @ 30°C is 0.6 psi. This means you have dP 1.0-0.6 =< 0.5 psi for vacuum suction system and desgn margin <5°C for water operating temperature. Challenging to achieve such in reality.

 

[georgeverghese]

@mint, for a while I thought you were pulling my leg when you said fruit and veg - until I saw the OP's post on this.
2 suggestions to get this tank down to 1psia:
a) Displace air in the tank with LP steam, then inject a cold water spray into the vapor space - pressure would collapse almost immediately
b) Use a 2 stage eductor with LP steam as motive gas.
c) Hook this tank into the suction of a oil flooded screw compressor which vents to atm.

Since you want 1psia, think this connected vacuum tank idea is not practical - a very large vac tank will be required.

 

[Snickster]

He said 1 psi delta P not 1 psia.

 

[shvet]

He said 1 psi delta P not 1 psia.

We usual peel other products at lower steam pressure and 1 psia