blower for methane

[mir]

Hi.
are in battle with colleagues about the power of a blower who:
- range 800 nm3/h methane
- suction pressure 0.025 mbarg
- pressure sent 0.050 mbarg
- is considered a blade blower

based on calculations each calculates a power ranging from 2 kw to 25 kw ....
Does anyone have an experience (or a spreadsheet) to give me an indication?

Thank you.
♪

 

[DoctorBomber90]

conditions of the incoming methane? is suction with pressure and ambient temperature?
Do you know anything about the geometry of the impeller?

 

[DoctorBomber90]

other thing. the blower in question is probably a centrifugal blower.
Is that correct?
Can you say the speed of entry and exit? because, what affects the power required to the fan, is not the pressure difference (although in small part) but the difference in speed(quindi la change in kinetic energy).
Thank you in advance.

 

[davidex]

- range 800 nm3/h methane
- suction pressure 0.025 mbarg
- pressure sent 0.050 mbarg

Does it seem inconsistent to me? There are no load losses of which to take into account ? cmq as they result 25 kw ? the power absorbed by the fluid considered as incomprehensible with a pressure change of 10pa would be 800/3600*10=2,2kw.

 

[paulpaul]

there is no suction temperature and it is not given to know whether the gas is pure methane or a natural gas (sometimes the difference is remarkable, depending on the composition of the gas). supposing a suction temperature of 25 °c and pure methane, the specific isoentropic work would be 3,4 kj/kg and the temperature of 26,5 °c. the isoentropic power would therefore be 0.54 kw, the actual one to the axis depends on the overall performance of the machine we know nothing about. hypothesize 0,65, so we would have about 0,83 kw. If you're interested, I'll explain a couple of procedures to calculate it.

What do you have to do with this very low pressure jump? Are you sure you find on the market machines that can realize it?

 

[stevie]

the pressures are probably relative, otherwise an application that would have absolute pressures close to 0 (unless it is a laboratory application).
considering the mass flow and the entalpic jump, in the hypothesis of an adiabatic compression you can have a theoretical indication...the main problem in my opinion is to determine the compression performance (intensive the total volumetric + mechanical) .

 

[DoctorBomber90]

the pressures are probably relative, otherwise an application that would have absolute pressures close to 0 (unless it is a laboratory application).
considering the mass flow and the entalpic jump, in the hypothesis of an adiabatic compression you can have a theoretical indication...the main problem in my opinion is to determine the compression performance (intensive the total volumetric + mechanical) .

I think so. The g di Home It's just... gauge(i.e. difference from English but is the relative one).
there is also mbara, where the a final stands for "absolute"(so it is absolute pressure).

 

[mir]

I'm sorry if I'm only here now... I didn't see all these answers.
the gas is biogas saturated at t about 40 ° at the entrance (I wrote methane to simplify the calculation)

the purpose is not to do upstream depression (which does not create because there is a large tank that guarantees continuity to the flow).

pressures are relative.

here I attach a typical blower, even if I don't understand how to interpret the suction charts and send: If I look at the aspiration I have a certain extent and if I look at the mandate I have another ... obviously in mass terms no principle is violated but we simply comprimo then I should increase the flow to the valley because of the increase of pressure. I think this is the only interpretation I can give to the charts.

Thank you.
♪

 

[paulpaul]

biogas means so many things if it has already been “pultio” is almost 100% methane, if it is “raw” can also contain 50% co2!
the calculation that I posted to you by the type of machine (within certain limits).

 

[mir]

is still to be purged.... biogas with co2 , water vapour, h2s, etc etc etc.

 

[davidex]

how to interpret suction charts and send

If the fan makes it work in aspiration, then consider the characteristic curve in aspiration, and vice versa if you do it work in mandata (or blower), then depends on where you have load losses, whether in front or behind (being a fan, usually it is assumed that or blows on something, for example a radiator, or aspires from something, for example a radiator).