The oil and cement industry had been conveying this material (grinded and hot ) for some time now.

From what I have seeen is not difficult to convey , though it requires carfull design of feeder bins and dust collector hoppers, also be carefull with the design of the screw conveyors shrowd after the dust collector, this material can refluidize and surge back, or even arch in the hopper, some plants have experienced lenghtly startup delays due to this simple matter. see that your supplier's scope includes the dust collector dust removal system.

Regards

marco ■

My email is mflores@tecmen.net ■

12m /sec seems a little too much for dense phase/ you might be talking about the saltation point, not the minimum conveying velocity. Nevertheless, dense or dilute phase are just names. You can even optimize to convey one part in dense and another part in dilute, that way your final velocity will not be so high and you can achieve the transfer rate with less pressure drop.

In some plants, the grinding and transport are done within an innert gas atmosphere, which is produced by combustion gases, which are hot. Temperature is below 300 dgrees C. Sometimes 110, just to get rid of humidity and allow use of bag filters.

Dense phase with 45 m/sec., final velocity can cause impacts in the elbows that will be shaking the structure. Try increasing your diameter 10 meters, or so, before delivery point, making sure that you never go below minimum conveying velocity. Or if you pass saltation point, in some section of your pipeline, do not go below saltation again.

Regards,

Marco Flores ■

Please note that dilute phase and dense phase are completely two different phenomenon, in dilute phase solids are fully suspended in the gas stream and in dense phase solids lie on the bottom of the conveying pipeline and are pushed by the conveying gas. Solids to gas ratios are not that important to distinguish these two mechanisms, it is the conveying velocity that determines whether the solids will remain in suspension while moving, or remain as a settled layer on the bottom of the pipeline. Below the saltation velocity, solids fall on the bottom of the pipeline, form a settled bed or dune, and require suficient force to move. This force is a combination of both velocity and pressure and it depends upon the physical properties of the solids and wall friction. In general the conveying velocity for dense phase at the feed point is less than 4 meters/sec and less than 10 meters/second at the terminal point, however, both velocity and pressure depend upon the particle size, wall friction, and bulk density among several other variables.

If petroleum coke contains any hydrocarbon residues, it will be necessary to use an inert gas for conveying because of the dust explosion hazards.

Hope that this helps.

Regards,

A. T. Agarwal

Consultant

Pneumatic Conveying Technologies

polypcc@aol.com

Ph and Fax: 304 346 5125 ■

I agree with the point that dilute and dense phase are two completely different phenomena and defining the boundaries has always been a debatable issue. But the calculations by Mr Subashpillai with inlet air velocity of 15 m/s and solid loading ratio of 6 can never be classified as a dense phase system and 200 mm pipe size is rather excessive for the requirement. With the outlet velocity of 48 m/s and solid loading ratio of 6 the shed. 40 bends would not last very long. ■

By the way to the ones buying petro coque , a new supplier is on the market. Ameriven has just finished comissioning its new unit in Jose Venezuela. You might want to get in touch with them.

regards

Marco Flores ■

we have installed a number of operating systems conveying cpc.pl contact our delhi office scordel@vsnl.com for more information ■

This sounds like a good application for a heavy duty chain conveyor? ■

A conveying line which is 20 meters horizontal, 40 meters vertical, and has five 90 degree bends does not appear to be an ideal application for a mechanical conveyor.

In my opinion, a dilute phase conveying system will be more suitable for this material because low velocity is not a requirement. It can be fed by a rotary valve or a feed hopper, although I prefer rotary valve because it is simpler to operate. Conveying line should not use long radius bends but "pocket-tees" to maximize bend life.

Regards,

A. T. Agarwal

Consulting Engineer

Pneumatic Conveying Technologies

polypcc@aol.com

Ph and Fax: 304 346 5125 ■

Many companies such as Redler have been doing just that for 40 years.

In my opinion the capital cost, operational costs and maintenance costs would be less than what is being suggested. However, the "footprint" would be greater.

C. Robinson

John King USA

309.698.9250 ■