Are you asking can it be done or are you asking someone to do the necessary analysis to tell you more?

Certainly you understand the very limited information provided will result in a wild guess at best. You do not state the product and its requirements, the environmental conditions, et al.

Can a concrete slab span 60m with a conveyor operating at 6000 mtph? Yes. Is this the best approach with high winds, waves and seismic criteria, who knows without having those criteria. There are other structures that may be more efficient.

What are the pile anchor features - one pile, two piles, three piles per pylon? What are the current, wind and wave conditions? How deep is the sea floor? What are the geological conditions?

No professional give a reasoned answer to so limited bits of information unless they have apriori knowledge? Can it be done within prudent economic guidelines. Maybe. What is necessary? Who knows? That comes with a purchase order, unless you find someone with the track record.

Placing idler supports at 3 meter centers with 6000 mtph is a very aggressive approach. You will not find many with such installations. This too can be done. ■

Completely without bias. You use 2,3 or more tube belts. That's it nothing better possible. Misalignment, weather protection, spray protection its all there. You might consider mounting the idler frames next to the pile landings on sprung sliding mounts to improve the curvature situation. Otherwise a complete doddle. You're very welcome. ■

Thinking aloud for a moment. Forget about spring restraints on the idler frames near the piles. Just use a suspension arrangement like Binder (Austrian) show on their displays. With a bit of modification it would fit your job a treat. ■

JKB,

The drop and rise of 100mm on a 60 m span and be accomplished.

Normally, we try to hold the vertical alignment to +/- 1mm within a 4-5 m idler span for overland systems. When the details of this geometry are weighed with the idler loading, for overland stringers, the accuracy seems justified.

The idler spacing can be adjusted, at the 60m span end structure, to allow a vertical rise of 100mm by having adjacent rollers carry the offset load. If the roll drops at the span end structure, adjacent rollers can be stationed to also carry the larger catenary curvature that may materialize.

It can be done as above. However,there are other methods that utilize span deflection of stringers to divide the offset tolerance difference. Slightly more complicated, but also does the job. ■

Don't forget that as the current or wind abates then the pile will swing back very rapidly as the strain energy releases. Sometimes there is overshoot as well, which is a well known phenomenon in supply boat service to monpod platforms.

Is the pile deflection the product of foundation rigidity as well as the other factors? In the shallows you should not reach anywhere near the same deflections as you expect towards the jetty. Check with your civil experts. Deflections would increase with taller but identical piles. Assuming there is a pile matrix at the seaward end then your last span might be fixed against the offshore jetty to maintain drive & belt transition alignments.

Examine what vertical curvature is involved to reach the shiploader etc...there are a few quite conventional issues which you cannot afford to overlook in the interests of a low piling expenditure. ■

John,

I am very interested in the Binder structural details you eluded to above. I tried Googling them to no avail. They have the BSH web address without a website.

I am aware of Prof. Franz Kessler's publications. I have had a number of discussions with him in person. I believe he has or had direct input to Binder on some advanced supports and belt curve engineering.

Is the Binder concept, the C-frame pivoted structure or something more elaborate? ■

Please remember my new sucessful rollers for conveyors, made out of RECYCELD-FUL-PLASTIC. They are the best, and the cheepest, if you use conveyors in wet or agresive area. They are also very less noisy!

More information you get via foerderschuettgut@arcor.de ■

Conveyors can take substantial deflection, even larger than 100mm in 60m span. The degree can be engineered into the design.

By example, observe the garland idler behavior in the Canadian Oil Sands and the Lignite fields in Germany. We have theodolite measured/planned up to 3 degree twist of stringers off center catalog the belts behavior with control misalignment.

The misalignment was repeated for 2 km between every set of stringers of, by memory, 10 m lengths. Roughly, this equates to 500mm offset between stringers. The offset is most prevalent at the two end idlers.

Therefore, one solution could be to place garland idlers at the 60m span ends. There are many such solutions that can resolve the predicted end float. ■

A small but important clarification to my last posting:

The offset is a measure of the movement between stringer ends verses the reference point, midway between the ends. The ends are each 10m apart from the reference point. ■

Dear Mr. JKB,

The issue would be how is the connection between horizontal civil structure and vertical civil structure. This can have following possibilities as decided by civil designer (marine civil structure designer).

1) Horizontal civil structure is continuous but resting on top of verticals, by appropriate method. In this case, horizontal structure, looking from top will appear to be of serpentine shape (very gentle). This will be easy to tackle as far as conveyor is concerned.

2) Horizontal structure is not continuous but it is one unit per span. In this case, the vertical can deflect in any direction and therefore, it would require combination of pivot and sliding type support in a manner appropriate to civil work. In this case looking from top, there could be sudden (minor) change in the direction of horizontal structure, at vertical. This would need different kind of consideration while designing the conveyor.

3) The horizontal structure is continuous for say 4 to 5 spans and then there is freedom of movement in appropriate manner, with respect to vertical. In this case, there would be sudden (minor) change in the direction of conveyor at every 4 / 5 spans.

Thus, the basic issue is type of civil structure being decided by marine civil engineering expert (this is not my subject). Having decided the specific shape pattern of the horizontal civil structure, attributed to deflection of the verticals, the matter is to be addressed accordingly by conveyor designer.

The afore stated connection pattern between horizontal civil structure and vertical civil structure, obviously is to satisfy the thermal expansion / contraction and deflection. The specific analysis etc. is an engineering work.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25871916 ■