Carbon black is supplied by its manufacturers in pelleted form because as a powder its flow properties are very poor. You should find out if your grade of carbon black is pelleted or not. Its pellets are generally very small, not like plastic pellets. In pelleted form it flows well in hoppers and feeders.

Carbon black pellets are not like plastic pellets because they are made by adhesives. They can easily break-up into their original powder/fluff form.

Dilute phase conveying is not used for pelleted carbon black because its high velocities easily break up the pellets into powder/fluiff.

To preserve the pelleted form, dense phase conveying is a must. And in dense phase also, conveying velocity is minimized by using primary and secondary air for conveying, through line injectors.

Please contact me if you need more help.

Regards,

Amrit Agarwal

Consulting Engineer

Pneumatic Conveying Consulting

Email: polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Dear Mr. Dhruv,

As informed by Mr. Amrit Agarwal, Carbon black supplied by manufacturers is in the form of pellets or fluff.

The N 220 & N 330 grades of carbon black that you convey have a particle size of 20 millimicron & 30 millimicrons resp, however these may not be the size of the pellets.

The pellet size distribution will influence the conveying properties of black, like air retention, ability to fluidise etc. The conveying conditions will largely depend on these parameters.

Blacks are known to be conveyed at velocities ranging from 2 to 40 m/s, with solids ratio as high as 20. If fines generation is a concern, then as Amrit suggested dense phase conveying with secondary impulse air is the way to go.

If fines are not a concern with your customer then a vacuum hopper loader can serve the purpose. Black fines have a tendency to form deposits in the conveying line. Please ensure the additional pressure requirements associated with those.

The filters need to have a filtration velocity of < 1 m3/m2/min. Also maintain the can velocity < 0.5 m/min. Do not use pleated filter.

Carbon Black dilute as well dense phase systems are operating in number of plants world over. If you need any assistance for building the system, contact me at solanairtech@sify.com

Thanks and Regards, ■

Dear dhruv,

Starting with your question “What would be solid loading ratio?”

Carbon Black 1500 kg/hr = 1500/3600 = 0.4167 kg/sec

Air 1.2 * 700/3600 = 0.2328 kg/sec

SLR = approx. 0.4167/0.2328 = 1.79

Carbon Black particles of 0.025 micron have a suspension velocity of approx. 0.02 m/sec.

Assume an air velocity of 100 times the suspension velocity = 2 m/sec.

In combination with a blower of 0.194 m3/sec, the pipe diameter is 350 mm.

The conveying pressure for a pipe with a diameter of 14” and only a length of 20 m has a backpressure of negligible value and certainly not the 400 mbar you estimate.

According to your calculation, the energy consumption per ton = 15 kW / 1.5 ton/hr = 10 kWh/ton.

Extremely high for such a light product and such a short distance.

Furthermore, I do not know whether the fine powder is caking, which causes additional unexpected problems.

Take care of the high explosion hazard.

A fine powder like you have is a real challenge for a filter, consult your supplier.

Take really care

Teus ■

Dear dhruv,

The suspension velocity is estimated with:

v-suspension = SQRT( 4/3 * (d * particle density)/(drag factor * gas density) )

d = particle size in m

particle density in kg/m3

gas density = 1.293 kg/m3

drag factor = approx 0.005 (average estimate)

The air velocity is calculated with:

air velocity = airflow/Pipe cross section area

A pipe of 60 mm has a cross section area of 3.141593/4 * 0.06^2 = 0.002027 m2

The end velocity = 0.194/0.002027 = 68 m/sec

For a velocity of 14 m/sec, the pipe diameter = 133 mm

This thread started with the description of the subjected installation parameters.

How were these chosen?

There must be some background to those values.

I am not familiar with any built installations, conveying this product.

Have a nice day

Teus ■

i have rich experiences in carbon black handling in both dense phase pneumatic conveying and dilute phase conveying system.Both types of carbon black you mentioned is very hard to conveying in pneumatic conveying system. It must be design unusually.Those kinds carbon black with those characteristics are very adhesive. If have any further qustion,please do not hesitate to contact with me.

BR ■