Sizing of hydropneumatic tank

Hello Dinesh, 

20000 L i.e. 20m3 is total volume of tank in your case and 6.6 m3 is maximum volume of gas in hydropneumatic tank. 

Can you please confirm which type of hydropneumatic tank you are designing? Is it sealed / dipping tube / vented?

The diameter (tank inlet orifice) is generally less than the larger pipe connecting from the main pipeline to the tank.. So if diameter of pipe adjoining the tank is 200 mm, then diameter of inlet orifice should be slightly less than that. 

Here is technote about modeling Hydropneumatic tank, for your reference, if you haven't gone through it yet. 

Modeling Reference - Hydropneumatic Tanks 

Here is related discussion about same topic of sizing hydropneumatic tank, which will help you in sizing the tank and understanding how to finalize the diameter of tank. 

simulation of hydropnumatic tank 

Thanks for the confirmation, that 20m3 is the volume of the tank which can be taken up for sizing (i.e calculation of diameter & length).

The hydropneumatic tank is sealed type and diameter of inlet orifice is less than the pipe connecting tank to main pipeline.

Regards,

Dinesh.Phusate

As Sushma mentioned, you would consider the 20 m^3 as the total tank size, and you would need to make sure a compressor is used to keep the "normal conditions" liquid volume at 14.3 m^3 (initial gas volume of 5.7 m^3, if you want to set up the system like the model.

It sounds like the HAMMER model is predicting that the initial gas volume of 5.7 m^3 will expand to a maximum of 6.6 m^3 (when outflow conditions occur), and compress to a minimum of 2 m^3 (on inflow). The 6.6 computed maximum is much lower than the total volume of 20 m^3, so you may want to try a smaller total tank size (and adjust the initial gas/liquid volume accordingly). When doing this, it will change the pressure/volume relationship in the tank, so your performance results may change. So, you cannot simply assume that a tank of 6.6 m^3 will be sufficient, since the pressure/volume relationship and tank performance will change. If you want to try a smaller total tank volume, you'll want to run some simulations and make sure that the maximum gas volume is still less than the total tank volume, but also that the transient envelope (min/max pressures) are still acceptable.

Thanks Mr.Jesse.

That was useful.

I have mentioned that hydropneumatic tank is considered with bladder, which is precharged with compressed air.

Still do we require comprerssor ?

Regards,

Dinesh Phusate

Hello Dinesh,

If you are using the bladder type hydropneumatic tank in which you can set the "pre-charged" pressure then there is no need for a permanent air compression system.

However, the key lies in specifying the "pre-charged" pressure. Setting it makes the model sensitive since it is used to determine the gas volume in conjunction with the total volume when the gas is compressed. To find the best "pre-charge" pressure you may have to run different trial runs.

As Jesse suggested, merely keeping the tank volume at 6.6 m3 won't suffice as the pressure-volume relationship s affected. When fixing the adequate tank volume you can run trials with different "pre-charge" pressures to determine the most suitable option.