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(OP)
Dear Professional forum members:

I would like to size the compressor air receiver volume.
The known condition is following:

1).Pmax (downstream consumer 2) = 7 kg/cm2g
2).Pmin (downstream consumer 2) = 6.8 kg/cm2g
* Not sure Pmin is decide from compressor vendor curve or
Downstream user minimum required pressure since there is
not minimum pressure of downstream user to be founded.

3).Q (air flow during the empty phase) = 17 Nm3/min
4).t (length of the emptying phase = 12 s (0.2min)
5) Pmax - Pmin = pressure drop during empty phase = 7-6.8=0.2kg/cm2g

Inserted these above to the formula

V = Q * t / (Pmax - Pmin) = 17 * 0.2 / 0.2 = 17 Nm3

Is this meaning that air receiver volume to be required at least 17 Nm3 ?

But, after the compressor be shutdown, the receiver unloaded during the empty phase
is only 12 s ? Is it possible case since 12 sec is very short?

Could you please kindly give me any guide or instruction?

Thank you so much.

You have to understand the purpose of an air receiver, especially if the compressor is of the reciprocating type. One of its basic function it to attenuate the pulsation. Secondly it provides a temporary volume of air so that the compressor does not operate continuously. Thirdly it accumulate condensate from moisturized air. My suggestion, contact your compressor distributor as it should have all the software to assist you in your quest. In the meantime I would suggest that you make a list of all the equipment that uses compressed air and tally the required air volumes, the necessary operating pressures and the amount of compressed air time required from each piece of equipment that the compressor distributor will need. Note that some piece equipment will imposed non-concurrent loads on the compressed air and that should be mentioned; also plan for future expansion.

I did it a slightly different way, but appear to get the same answer, you receiver needs to be at least 17m3, not Nm3, m3 on the basis that very little air will come in whilst a lot is going out. Can it do it - yes, but you need to size your nozzles, pipe and equipment suitable for the max flow rate of 17Nm3/min.

however if your actual air usage is only 3.4 Nm3/hr (17 x 0.2), then your compressor needs to match the steady state load otherwise it will load and unload many times a minute which won't do it any good at all...

The range of 0.2 bar looks very small and hence you should aim for a total receiver size at least 1.5 times your minimum in order to smooth out the supply and delivery of air.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

In the paper manufacturing we provide (2) air systems from the same compressing station. Referred to as essential & non-essential. Paper has very large equipment that requires a controlled shutdown and these critical pieces are fed from the essential side, all else from the other.

Again, I agree with Littleinch...

Your difference between Pmax and Pmin is too small. This is causing your receiver to be too large when general rules of thumb are applied.

Do you really want to purchase something this large ?

Review and confirm these numbers...

MJCronin
Sr. Process Engineer

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