Pneumatic Transfer of Hydrated Lime

Posted in: , on 2. Mar. 2008 - 09:45

I am working on a water potablization project with CO2 and limewater injection.

Lime Storage Silo Capacity: 50 m3

Density of Hydrated Lime Powder: 480~500 Kg/m3

Lime transfer rate from 50 m3 Storage Silo to 12 m3 Operating Silo: 24 m3/hr

(i.e., to fill the operating silo in 30 minutes)

Accessories under the Storage silo (50 m3):

Bin Activator

Slide Valve

Rotary Airlock Feeder

Pipe size: 4 inch

Pipe material: CS

Pipe length: 13 meter horizontal, 10 meter vertical, 13 meter horizontal

How can I calculate the blower capacity to transfer the hydrated lime powder from 50 m3 storage silo to 12 m3 operating silo?


Sarmad Hameed

SETE Energy Saudia

Jeddah-Saudi Arabia

Phone: 00 966 2 622 0022, Ext. 3046


Re: Pneumatic Transfer Of Hydrated Lime

Posted on 2. Mar. 2008 - 10:23

Dear Mr Samrad Hameed,

As you already asked for in another thread today, it is necessary to know the pneumatic conveying properties of the hydrated lime.

You have already chosen the pipe diameter, which is in fact the limitation of the installation as the maximum SLR at a certain pressure and velocity is depending on the pipeline length and together with the pipe diameter and the necessary air velocity, the capacity is determined.

The approach should be:

(1)Determine the suspension velocity of the hydrated lime particles.

Together with the particle size distribution and material density (2211 kg/m3, Wikipedia) the suspension velocity can also (roughly) be calculated.

(2)The end velocity (pressure system) should be approx. 2.5 times the suspension velocity (powdery product)

(3)If the relation SLR(hydr.lime)=function(distance) at a certain pressure and velocity is not known, a pipe line diameter has to be chosen.

(4)The chosen pipe line diameter together with the air velocity gives the compressor capacity.

(5)The rotary lock air losses as a function of the convey pressure have to be added to the compressor performance.

(6)The material loss factor should be known from other installations.

An easy way to find out this material loss factor is to calculate this factor back from bulktruck unloadings.

Make sure that you are using the same calculation algorithm.

(7)After modelling the pipeline and filter, a capacity calculation can be made.

(8)Depending on the resulting capacity and the desired capacity a new pipeline diameter is chosen and the design procedure is repeated.

Although the installation seems to be rather common and simple, the calculation of it shows that there is more science involved in pneumatic conveying than it looks at first sight.

have a nice day