# Thread: Review and help needed for pneumatic conveying system design

1. ## Review and help needed for pneumatic conveying system design

Hello,
so, I am designing open system vacuum conveying system similar to as shown in attached photo.Review-of-pneumatic-conveying-system[5].jpg.
I have following data estimated(as per logic diagram attached here. Courtsey: pneumatic conveying design guide by David mills..)Capture.PNG

Available data
Bulk density of :
-Material flow rate required(Mp)=10,000kg/h
-Conveying distance(L)=45m
-Pipe bore(guessed)(d)=0.2032m/(8")
-Delta P(pressure drop)=?
-Conveying air inlet velocity=36m/s
-Air mass flow rate(Ma)=1.32kg/s
-Air requirements= 1.617 cubic-meter/s or 3426.2 CFM.

As shown in the image there will be two 90 degree bends. and cyclone inlet is located at 10 feet height(so vertical height of pipe around 8 feet)
Assumption:Pressure at the inlet of the pipe(from which the material will enter) will be equal to atm. pressure
I am also attaching an image of cyclone design parameter as shown in the book. cyclone.PNG

I wanted to know whether the calculations are correct and how to design the cyclone from available data.
Any help will be much appreciated.

Thanks

2. Dear Vishal Panchal,

From the information in your installation description, the following remarks:

The material and the material properties are not given.
The material losses cannot be estimated.

The solid loading ratio can be calculated as material mass flow divided by the air mass flow.
SLR=10000/3600/1.32=2.1

-Delta P(pressure drop)=?
The pressure drop (vacuum) can be calculated as:
Vacuum = 1.13/1.617-1=0.3 bar.

A cyclone in combination with a positive displacement vacuum pump is not a good idea.
A cyclone does not filter all the dust, which then passes the blower, which will wear out fast.

It is not clear, whether all the partial pressure drops are calculated.
(air, velocity, acceleration, suspension, material/dust separator, rate control, etc.)

Apart from designing a vacuum system, the technology is also an important issue, s.a. nozzle intakes, valves, rotary valve(-leakage), etc.

Take care

3. Originally Posted by Teus Tuinenburg
Dear Vishal Panchal,

From the information in your installation description, the following remarks:

The material and the material properties are not given.
The material losses cannot be estimated.

The solid loading ratio can be calculated as material mass flow divided by the air mass flow.
SLR=10000/3600/1.32=2.1

The pressure drop (vacuum) can be calculated as:
Vacuum = 1.13/1.617-1=0.3 bar.

A cyclone in combination with a positive displacement vacuum pump is not a good idea.
A cyclone does not filter all the dust, which then passes the blower, which will wear out fast.

It is not clear, whether all the partial pressure drops are calculated.
(air, velocity, acceleration, suspension, material/dust separator, rate control, etc.)

Apart from designing a vacuum system, the technology is also an important issue, s.a. nozzle intakes, valves, rotary valve(-leakage), etc.

Take care
I have calculated solid loading ratio from the equation given in the book. SLR=mass flow rate of material/3.6*mass flow rate of of air.
The system is not of a critical importance I just want to see if this is feasible. Material to be conveyed is cotton from the trailer to the ware house.
What if we use filter media at the inlet of blower? This might reduce dust accumulation in the blower? I just want to keep the system simple as possible and don't mind leakage or loss of power/efficiency. But I don't mind using rotary lock at the bottom of the cyclone if neccessary. And regarding all other partial pressure drops I don't know about those terms. Many thanks

4. Dear Vishal Panchal,
The formula that you use is correct and results in:
SLR = 10/3.6/1.32= 2.1 (not 0.58)

The cotton is a soft, fluffy and light staple fibre in a boll with a very low density.
A pick-up velocity of 36 m/sec seems far too high.

A filter before the inlet of the blower takes over the function of the cyclone.
Ergo, the cyclone is no required anymore.

May be, if you design a vacuum-pressure system with a cyclone and a centrifugal fan, you can blow the cotton directly into the warehouse.