Pneumatic Conveying Limits

Posted in: , on 8. Jul. 2008 - 19:32

Dear gentleman,

I want to design a pneumatic conveying system to transport barites with a capacity of 60t/h. The equivalent lenght from point of unloading to discharge point is 300m. Initialy I used the method explained in Perry´s Chemical Engineer Handbook. With this method I found this basic design:

Pipe diameter: 12 inch

Air flow ratio: 12000m3/h

pressure drop: 1.5kgf/cm2

Is that right?

I have other questions. Is possible to use pressures beyond 3kgf/cm2 to transport barites in a higher mass ratio (I use 4kg of barite/kg of air)? What is the maximum transport capacity, in dilute phase, for transfer barites using a 6inch pipe diameter. Mass ratios higher than 4kg of barite/kg of air can be achieved?

Thanks for the attention

Joo Paulo Laudares ■

Transport
Conveying
Pneumatic Conveying
Dilute Phase Conveying
Conveying Modes
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Re: Pneumatic Conveying Limits

Posted on 8. Jul. 2008 - 05:59

For this kind of lengths and rates lean phase systems are not feasible on power consumption. From the figures provided by you; we looking at something like a 1 MW air mover.

Dense phase will be more appropriate for this situation. In dense phase you can have 4 bar conveying pressure higher SLR and lower conveying velocities. I would also recommend that you look into mechanical conveying also and compare the merits. ■

Mantoo

Thanks!

Posted on 8. Jul. 2008 - 07:18

Thank you Mantoo,

One of the problems that I have to design this particular system is that I don´t may use any automation or control. Is feasible design a dense phase conveying system without any control or automation?

Best regards,

Joo Paulo Laudares ■

Re: Pneumatic Conveying Limits

Posted on 8. Jul. 2008 - 08:11

you can if you want to employ a full time operator. I will not recommond it though. it will require a tiny plc to run. ■

Mantoo

Re: Pneumatic Conveying Limits

Posted on 8. Jul. 2008 - 10:12

Dear Joäo,

Firstly, you seem to spread your questions over more than 1 thread.

It might be better for the overview to combine your questions in 1 thread.

I propose this thread.

I did a quick calculation of the system as you describe it.

The result, I get, is 117 tons/hr at 1.5 bar

The design is not very economical, looking at the velocities, which are far too high.

(see attachment)

Pressures higher than 2.5 bar to 3.0 bar increase the chance of choking and are not energy efficient anyway.

Pressure control is very easy, even without a PLC.

Your formula is not understood.

F.i. for cement with a bulk density of 1.1 tons/m3, the begin velocity would become 38 m/sec.

Normally at 1.5 bar, a velocity of 6.5 m/sec to 7.0 m/sec is sufficient.

Note : The used pneumatic conveying properties might differ from your product

have a nice day

teus

Attachments

joaobarite (PDF)

■

Teus

More Doubts...

Posted on 8. Jul. 2008 - 11:30

Dear Teus,

My goal is to design a pneumatic conveying system with a capacity of 60 tonnes / h. For this I used a method based on a group of nomographs made by Flotronics, which is shown in reference Handbook of Chemical Engineering; Perry. I really do not know if this method is most appropriate for the project, but this is the only reference that I have.

The method begins by calculating the speed of air, associated with bulk density of the material. With the apparent density of barite informed, the table shown a speed of 54.25 m / s (Is it right? This is high for barites?).

The second part of the method involves defining the air flow for a given pipe diameter. For the speed of 54.25 m/s, the second nomograph indicates a flow of 12816 m3/h of air to a pipe of 12 inches.

With the value of the flow and defined capacity I found a ratio of solid. The value for this is 4kg of barites/kg of air. With this SLR I could define that, for an equivalent length of 300 meters, the pressure loss on transport would be 1.5 kgf/cm2.

These values are very diferent when compared with the values that you show. The method that I used have a poor precision?

How can I get the same information about pipe diameter, air flow, SLR and pressure drop without using this method? There is some free software or Excel sheet to do this type of calculation with more accuracy?

Thanks,

Joo ■