Sudip,

Convey the alumina at the lowest possible velocity because pipeline erosion is exponentially related to conveying velocity. Dense-phase conveys at velocities an order of magnitude lower than those of dilute-phase. The lowest possible dilute-phase velocities occur at the pressure drop minimum point on the Zens conveying diagram.

The wear characteristic of long radius sweeps, e.g. 10D, is worst, 5D is only slightly better. There are special bends such as the Gamma bend, Vortex bend and blind tee that can significantly reduce erosion. In certain extreme cases the best results are obtained by conveying through rubber hoses.

Undoubtedly conveying companies and various consultants will offer their design services, but at a cost. I do not recommend commercial software; the results must be taken on faith because key program calculations are proprietary and inaccessible to the user.

I would recommend a short conveying course to quickly bring you up to speed. From time to time companies like Coperion-Waeschle and Zeppelin offer courses and workshops that are excellent and well worth the investment.

Regards,

Dennis Hauch ■

Hello Sudip,

I could not see any information about the alumina transport rate, air flow rate, pipe diameter and pipe length! Pipe layout would alos play a vital role !

We have been quite successfully solving alumina transportation and erosion related problems for Norsk Hydro in Norway.

Unfortunately as it has been already pointed out by Dennis there is no ready made software for such purpose and even if you get one you are in for a even bigger problem !

Hence in such situation it is best to try to solve the problem based on some lab scale test results or data collected from the actual plant.

You may please contact me at the address given below. My email address is biplab.k.datta@hit.no

Biplab ■

Hello Sudip,

I have recently joined this forum - see my thread on pressure drop across an orifice plate. If I look at the number of views and the number of answers, it seems to me that in this forum there are a lot of persons looking for answers and very few giving answers!

Let me try to give you some advice on your wear problem.

1 Replace the bends with tee-pieces with one leg blanked off.

Material will collect in the blanked-off leg. The solids entering

the tee-piece (bend) will collide with the material and not the

metal. Bends like this outlast normal bends at least 4 times.

The downside of this arrangement is that it increases your

pressure drop across the bend. If you have enough pressure

to play with, it is a small price to pay.

This arrangement is basically a short radius bend. As you

know, the particles are decelerated in a bend and you need

a straight after the bend to accelerate the particles again. If

you replace your normal bends with a blanked-off tee, the

deceleration of the particles will be more pronounced. It is a

common phenomena for solids to drop out of the air stream

just after a bend. This can lead to blockage. If you had

blockage problems in the past, you must be aware of the

above.

2 You can use ceramic lined bends. Although much more

expensive than normal bends, they outlast normal bends

several times. If you take the savings in downtime and

maintenance cost into account, they are well worth it.

Good luck,

Jan van Heerden ■