Dear Nymph,

Although an eductor is often used in pneumatic conveying, the application of an eductor is mostly limited to small and low capacity installations.

The energetic efficiency is rather low.

The principle of an educator installation is creating an under pressure at the sugar intake through a nozzle, where the velocity energy is increased to a high level.

After the mixing zone, the velocity energy of the air is converted in a venturi into velocity energy of the sugar/gas mixture and pressure energy.

At the low pressure zone, the temperature becomes very low (- 30 degrC.).

The venturi pressure is used as the conveying pressure for the sugar.

From the venturi on, the system is a standard pneumatic conveying system.

The eductor with venturi is a replacement for a rotary valve (with a metered rate) with a blower.

The latter system is easier and more reliable to design.

The eductor system is very depending on the circumstances, s.a. how much air is entrapped at the vacuum intake and the temperature of the used compressed air.

see:

http://www.foxvalve.com/

Your system of 20 tons/hr over a length of 92 m, including 70 m vertical up, seems a rather high rate and a long system for an eductor.

A quick calculation with an estimated producl loss factor learns that approx. 0.5 m3/sec is needed at 1 bar in a 6” pipeline.

I doubt that there is an eductor that delivers 1 bar conveying pressure after the venturi.

Have a nice day

Teus ■

You can probably convey sugar using eductor / lean phase system at the required rate / distance.

But in reality the sugar breakage will be very high and it will not be practical.

If you want to convey sugar and do not want high particle breakage then you will need to go with

a Dense Phase system. ■

Dear Nymph, Mantoo,

Indeed, pneumatic conveying of sugar results certainly in “fine sugar”.

The particle size of 0,650 mm and the sugar density of approx. 1600kg/m3 results in a suspension velocity of approx. 4 m/sec.

A conveying velocity of 15 to 20 m/sec is required to prevent sedimentation.

Rather high for a friable product like sugar.

Moreover, the used conveying air must be very dry as sugar is hygroscopic and the temperature after the nozzle can drop to very cold temperatures, causing condensation.

Also, you can contact:

http://www.enviro-engineering.de/index.php

Success

Teus ■

Dear Nymph,

Dilute phase conveying of sugar is pretty common in the USA. Main concern is moisture if the conveying air is humid. System must be designed to prevent condensation. Particle attrition is a concern if there is a limit on fines in the final product specifications.

Venturi type systems for a 22 tons/hr conveying rate will be economically less attractive than the standard blower/rotary valve systems because of their poor effieciency. But, theoretically, they can be designed for this conveying rate.

Regards,

Amrit Agarwal

Pneumatic Conveying Consulting

Email: polypcc@aol.com ■

Be aware also that sugar is a combustible product and under the right conditions, is highly explosive. You need to exclude all sources of combustion and provide adequate electrical grounding of the equipment and electrical continuity across the pipeline joints.

Michael Reid. ■

The real problem in sugar conveying is poor flow of sugar from dust collectors and feed bins. It is very important to use dry air atmosphere in these vessels. I have seen many bins with their beaten up bottoms by hammers to maintain flow. Use of bin-dischargers is also recommended.

Regards,

Amrit Agarwal

Pneumatic Conveying Consulting ■