Dear Shri Chaithanya,

Are you referring to belt turnover in return run so that carrying side remains as the top side even in return run?

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 ■

Turning Device is not clear?

1. horizontal curve?

2. belt turnover?

Placing a turning device in the middle of the conveyor must be a horizontal curve.

Placing a belt turnover in the middle has not useful function.

There is a lot of information on these two points. Do a search. ■

Hello V. Chaithanya..

Still no answer to what you are really looking for.

A turnover in the middle of the belt could be taken to mean turning the top and bottom belts around. The carry side is then on the bottom and ther return is then on the top.

I did this for my 7.5km dual carry conveyor. Is this maybe what you have in mind?

Cheers

LSL Tekpro ■

Are you considering belt turnovers at either end of a conveyor to ensure that belt runs always on clean side?

OR

Could this be the "offloading of material from the belt by lifting the belt about its longitudinal axis "?

This method is typically used as an alternative to intermediate belt ploughs.

There was quite an extensive discussion on the forum in this regard.

I believe one of the conclusions was that in hard rock situations plouhgs would be rapidly destroyed.

The problem with raising the belt to discharge material (Typically by using flat idlers to lift belt beyond the trough) is mainly that the belt would tend to slip down on the raising idlers resulting in edge damage.

An alternative could be by using a central rubber lagged and shaped wheel to raise teh belt hence discharging its load on either side.

Please confirm your needs.

Adi Frittella ■

Hi Adi..

Good to hear from you.

For what it's worth, we have done a few (but only a few) belt tilt discharges.

By tilting the belt with a rapper, you can get most of the stuff off the belt, and if you design the tilt nicely, it actually doesn't damage the belt, and as if defying our good friend Issac (g) Newton, it doesn't de-train much either.

As for the central wheel, this method leaves a strip of material on the middle bit, which then requires the dreaded plough again to remove it, so... belt tilt is better, (that is if your client is too stingy to buy a proper tripper..)

Cheers

LSL Tekpro ■

Dear all,

What will be the share of power consumptions due to turning devices in terms of percentage ?

Thanks & regards, ■

I am not sure what you are trying to say Sganesh..

Cheers

LSL Tekpro ■

Dear Mr.Spriggs,

Please assume that the motor consumes 100 amperes when turning devices are not installed. If turning devices are introduced, can there be significant increase is expected in the motor's amperes? If yes, how much?

Thanks for your participation & regards, ■

Hi there Sganesh..

Turning the belt is normally used on longer belts to ensure that the return strand is "dirty side up" to avoid return fines spillage. Flip it upside down at one end and flip it back again at the other.

You may safely assume that the additional power consumed is negligible.. especially when compared to the power as required for the longer belts..

Cheers

LSL Tekpro ■

Dear Graham,

I beg to differ and the power consumption of a belt turnover. First, you need many pulleys. For a modern conveyor where belt sag in the turnover needs to be controlled, you will need about 10 such pulleys with differing drag losses as they hold the belt in a flat ribbon configuration. Next the pulleys will have the belt twist and bending forces applied. Rheological losses and bearing losses increase drag in the turnover. Although we have not made the rheology analysis to date, we will do so on the next large turnover project.

On another note, what about product flow losses in chutes & skirts? We will publish a paper on this subject similar to the presentation we made at Prof. Alan Roberts 80th birthday party. The losses are staggering when compared to overall energy consumption of a horizontal running short to medium length conveyor. ■

Originally Posted by nordell

Dear Graham,

................. The losses are staggering when compared to overall energy consumption of a horizontal running short to medium length conveyor.

Thank you Mr.Nordell. Could it be 20% high or 30% high or more than that? Is there any proven calculations?

Best regards, ■

Delighted you disagree with me Larry.. (If you didn't I would worry that there might be something wrong with you!)

Anyway, if you were to give it a bit more thought, and put out that strange thing that you are puffing away on, I am sure you will eventually come round to my way of thinking, after the smoke has cleared, and you have had a nice lie down.

Regarding the staggering losses you have, I'm very sorry to hear about that...

We here in South africa design out such losses, therefore preventing us from suffering from the dreaded staggerings.

Anyway.. you may all rest assured that belt turn-over additional power requirements may be considered negligible, especially as they are only fitted to the longer conveyors, normally of significant installed power.

Cheers

LSL Tekpro ■

I offer one example of transfer chute loss vs total conveyor demand power w/o chute loss:

Length ............. 500 m

Lift .................. 0 m

Speed .............. 6 m/s

Tonnage .......... 2000 t/h

Material ........... 900 kg/cm

Non-Round rock

Drop Height ...... 4 m

Power Loss ....... 20 kW (direct drop)

Total Demand Power 138 kW(direct drop) = 17% to accelerate material over basic w/o acceleration

Curved hood & spoon 5 kW in 123 kW = 4% to accelerate material over basic w/o acceleration ■