Dear venu kumar,

Your subject is extensively discussed in thread:

https://forum.bulk-online.com/showth...9211#post59211

In addition, can you explain why you have decided for a conveying pressure of 4 bar to 7 bar?

Long pipelines at high conveying pressures are sensitive for choking and if that happens, you have a long problem.

Take care

Teus ■

Just for my interest, is the type of compressor relevant to the calculations in pneumatic conveying? ■

Dear designer,

Is the type of compressor relevant to the calculations in pneumatic conveying?

No and Yes.

Fir a single pneumatic conveying installation calculation, where a fixed air flow is assumed, the pneumatic conveying installation does not know where the air comes from.

However, a pneumatic conveying installation is calculated in an iterative calculation algorithm.

During this iteration, the pressure is iterated until the input and the output values are consistent.

At various pressures, the airflow of a compressor changes and those changes influence the calculation. (different volumetric efficiency at different pressures)

(drive rpm variations at different pressures also influence the airflow, although I do not account for this variations in my computer program)

In addition, various types of compressors determine the design pressure.

Blower, up to 1 bar

Oil free screw compressor (single stage) up to 3.5 bar

Oil free screw compressor (double stage) up to 7.5 bar

Oil filled screw compressor (single stage) up to 12 bar.

Turbo compressor with controlled diffusors with constant mass flow.

Vane compressors up to 2.5 bar.

Vacuum blowers up to 0.5 bar vacuum

Oil free screw compressors up to 0.65 bar vacuum

Vacuum blowers and oil free screw compressors with pre inlet up to 0.85 bar vacuum.

If you design a high pressure conveying system, you also choose a certain type of compressor.

There is a feed back influence of the pneumatic conveying system on the compressor performance.

Have a nice day

Teus ■

Yes.

I was somewhat confused when the thread starter specified the type of compressor first, then asked about doing the calculations, but confused me even further (but it's not hard to confuse me) by specifying the pressure???

I thought you'd do the calculations first to establish the required air flow and pressure, then choose the compressor to suit these requirements. ■

Dear designer,

You are right and not confused.

Specify the installation performance first, then calculate the various designs (high pressure-low pressure), evaluate the designs and then make the choice. (lowest energy consumption-lowest investment-lowest maintenance-highest reliability).

Example:

Horizontal length 800 m

Vertical length 30 m

8 bends

Fly ash 150 degrC

Pipe line 16”

208 tons/hr at 2.5 bar

2.43 kWh/ton

Pipe line 14”

148 tons/hr at 2.5 bar

2.29 kWh/ton

Pipe line 20” / 24”

200 tons/hr at 0.7 bar

1.70 kWh/ton

Pipe line 12” / 14”

150.0 tons/hr at 4.2 bar - 2.87 kWh/ton – 4.2/150=0.028 bar/ton

156.0 tons/hr at 5.0 bar – 3.20 kWh/ton – (5.0-4.2)/(156.0-150) =0.133 bar/ton

159.5 tons/hr at 5.5 bar – 3.40 kWh/ton

162.2 tons/hr at 6.0 bar – 3.61 kWh/ton – (6.0-5.5)/(162.2-159.5) =0.185 bar/ton

163.1 tons/hr at 6.2 bar – 3.70 kWh/ton

163.6 tons/hr at 6.4 bar – 3.79 kWh/ton

164.1 tons/hr at 6.5 bar – 3.83 kWh/ton

165.3 tons/hr at 7.0 bar – 4.07 kWh/ton

Sometimes, pneumatic conveying is …….. confusing?

have a nice day

Teus ■

Originally Posted by Teus Tuinenburg

Sometimes, pneumatic conveying is …….. confusing?

I'll stick to handling by mechanical methods then ■

Dear Venu,

If you want to know “how they arrived at that calculations”, I suggest that you ask them first.

Additionally, it would be interesting for us to know also.

I noticed that you already requested the article and spreadsheet from Mr Agarwal.

That should help you for a start.

Also visit:

https://news.bulk-online.com/

and search the pneumatic conveying section.

Cross checking installations is done by getting more than one quotation and talk to the vendors.

(Designer;this might increase the confusion)

More specific information generates more specific answers.

Have a nice day

Teus ■

dear mr venu

you can try assuming: solids loading ratio or SLR (mass flow rate of solids/mass flow rate of air) = 20 and 30 (higher the value: the more dense is your system).

with 150 t/h and SLR (=20 say) you should be able to get your conveying air flow rate. Then convert mass/s to volume/min (e.g. at FAD etc).

some comments on your post:

a) your 4 to 7 bar is way too much of a wide range;

b) 4-7 bar may have been arrived at with a large margin on the predicted value of pressure drop;

c) type of compressor has nothing to do with theoretical air flow rate calculation.

regards

ssmallick ■

Dear ssmallick,

Following your instruction:

Air mass flow=150000/20 = 7500 kg/hr air.

The free air delivery is the approx. 7500/1.2=6250 m3/hr # 104 m3/min # 1.74 m3/sec.

How do you proceed then further?

Calculation of pipe diameter(s)?

Calculation of pressure drop?

In addition, “what if” your calculations lead to too high pressures and too low velocities due to the too high pressure drops?

In addition, “what if” you want to design for a specific pressure drop in relation to a chosen compressor type or feeder?

Interesting to know

Have a nice day

Teus ■

Originally Posted by Teus Tuinenburg

Dear venu kumar,

Your subject is extensively discussed in thread:

https://forum.bulk-online.com/showth...9211#post59211

In addition, can you explain why you have decided for a conveying pressure of 4 bar to 7 bar?

Long pipelines at high conveying pressures are sensitive for choking and if that happens, you have a long problem.

Take care

Teus

Dear Mr Teus

Sir

We often discussed and concluded that high pressure with long pipeline is always sensitive to chocking and i clearly understood the outline . Can you put a more light in terms of technical reason why it is so and what is the desirable length of conveying with this pressure range (4 to 5bar). I mean is that has something to do with velocity or any thing else. ■