Thread: HELP PVC grain pneumatic conveying system vaccum

1. HELP PVC grain pneumatic conveying system vaccum

hello ,
I have a problem concern extanding piping installation of an already installed PVC grain pneumatic conveying system (vaccum) my question are :
Q1: how can i calculate the maximum distance (of piping) that my vaccum pump can handle to transport pvc grain from the pickup point to the hopper?
Q2:how can i calculate the pickup velocity of the pvc grain ?
if someone could give me thhe steps that i should follow to solve this problem?
Thanks

2. installtion shematic

installtion shematic

capture2.png

Without installation- and performance data, it is impossible to answer your question.

At least required are:
- Pipe diameters
- Lengths horizontal
- Length vertical
- Operational conveying rate with corresponding vacuum
- Vacuum pump type

From your picture, it is impossible to derive that information.

That you show 2 vacuum pumps in series, could indicate, that you use 2 centrifugal fans in series to reach the required pressure drop.

In that case, the fan curves are also required.

The installation could work at a longer distance with a higher vacuum or a lower conveying rate.

Seems to be a small installation anyway, so, why not just try it?

Calculating the pick-velocity of the pvc grain is done through dividing the airflow, corrected for the absolute pressure at the intake by the cross-sectional area if the intake pipe.

Take care

4. Originally Posted by Teus Tuinenburg

Without installation- and performance data, it is impossible to answer your question.

At least required are:
- Pipe diameters
- Lengths horizontal
- Length vertical
- Operational conveying rate with corresponding vacuum
- Vacuum pump type

From your picture, it is impossible to derive that information.

That you show 2 vacuum pumps in series, could indicate, that you use 2 centrifugal fans in series to reach the required pressure drop.

In that case, the fan curves are also required.

The installation could work at a longer distance with a higher vacuum or a lower conveying rate.

Seems to be a small installation anyway, so, why not just try it?

Calculating the pick-velocity of the pvc grain is done through dividing the airflow, corrected for the absolute pressure at the intake by the cross-sectional area if the intake pipe.

Take care

Centralized conveying system
the installation like shown in the shematic ...we have pip installation from the pump to the filter then from the filer to the vaccum receiver
then from the vaccum receiver to pickup point .
-----------------------------------------------------------------
Lenght :
-From the pump to the vaccum receiver
Length vertical 3 m
horizental 80 m
-From the vaccum receiver to the pickup point
horizental: 70 m
vertical : 3 m
--------------------------------------------------------------------
two pump in serial each one of them has 265 m^3/h (pumping speed)
- Pipe diameters : 50 mm
- Operational conveying rate with corresponding vacuum ( from where i get this information?)
- Vacuum pump type ( ddd.PNG

Centralized conveying system

- Operational conveying rate with corresponding vacuum ( from where i get this information?)
The operational data from your
already installed PVC grain pneumatic conveying system (vaccum)
Best regards

6. ok tank you sir ,

so what i need is not the result but the theorical steps that i should folow ....i read the article written by A.T. Agarwal i am not sure if is there any diffrent bettween blower installation (positive displacement ) and an aspiration systeme ( negative displacement) ( like in my case the pump aspirate the grain )

...tank you very much sir for your help ..and i am sorry for my english i am not a native speaker

The theoretical steps are described in the article of Mr. Agarwal.

The first practical step is to calculate the existing installation and derive from that calculation the K-factor.

The second practical step is to calculate the modified installation with the derived K-factor and evaluate the new calculation results.

There is a difference between a pressure system and a vacuum system.
The difference lies not in the fundamental conveying physics, but in the behavior of the air mover.

Pressure system:
Compressor takes the air in from the ambient conditions and delivers an almost constant air mass flow in case of a Positive Displacement compressor.

Vacuum system:
Compressor takes the air in from the vacuum conditions and delivers a decreasing air mass flow with increasing vacuum, in case of a Positive Displacement compressor.

In case of a non-PD compressor, like a fan, you must follow the corresponding curves.

A compressor performs according to the intake conditions

Best regards
Teus

8. Originally Posted by Teus Tuinenburg

In case of a non-PD compressor, like a fan, you must follow the corresponding curves.

i get confused
what i understand from you is that in my case i will not applicate the theoretical steps that are described in the article of Mr. Agarwal.
am i right ?

what i understand from you is that in my case i will not applicate the theoretical steps that are described in the article of Mr. Agarwal.
The theoretical steps, you are referring to, are always valid.
When you apply those theoretical steps, you must account for the compressor behavior in the respective installation (pressure or vacuum)

Keep in mind that a compressor is the same as a vacuum pump.
Both machines compress gas from a low pressure to a high pressure.
(The same physical blower can be used for pneumatic pressure conveying as well as for pneumatic vacuum conveying)
A PD compressor has a constant displacement volume, which is not influenced by the pressure drop.
A fan has a flow rate displacement, which is depending on the pressure drop over the fan.

Best regards

10. ok sir thanks..

how i can calculate the k-factor practically?

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