Namaskar Mr Ganesh,

Its a bit of wide open question much like my taking a chance diving

into the Ganges with a paper cut on laundry day.

Transport of bulk materials from A to B depends on many factors

including

1. belt width

a. belt thickness

b. belt age

c. splice type

2. belt speed

3. troughing idler spacing

4. return idler spacing

a. flight distance between transfer points

b. flight angle/flight rise and run

5. drive voltage

a. cost of electricity per kilowatt hour

b. line drop of high voltage feeder electrical cable

6. amperage at start up

7. drive type

8. drive efficiency

9. friction of trough belt and idlers against belt

10. lagged or unlagged pulleys

11. dust accumulation at tail pulleys and drive units

a. dust plows at tail pulleys

b. maintenance of belt-shoveling, greasing, belt training, replacement of bad frozen idlers when needed

12. belt wear due to dust accumulation

13. transfer points, impact idlers, Impact beds

14. weather-if belts are overland conveyors or short distance conveyors.

15. belt slippage if wet

I probably missed some things but.................... its hard to really pin down unless we know what is being moved too.

The same thing is also an issue for rail transport by using the electricity used to power the wheel drive motors of the locomotives

on the railroads and the distance hauled where a net charge per ton is made to the receiver of the goods whether their railroad

cars are used or not.

So many variables already not including ROI, IROI, depreciation schedules,

cost of repair inventory(spares) belting,splice kits, etc., the present value of a Dollar

or the Rupee in the entire scheme is but one more issue to throw at the

wall to see if it sticks. ■

Dear S. Ganesh,

Power = Force * velocity /efficiency= m * {g*sin(alpha) + f*g*cos(alpha)} * dL/dt/efficiency

From the formula:

Vertical (alpha = 90) requires more power as long as f (friction) <1

Longer distance (dL) requires more power.

Higher velocity (shorter dt or more tons per unit of time) requires more power

A low energetic efficiency of the system (pneumatic or grab crane or belt, etc.) requires more power.

All basic engineering knowledge.

Defining a benchmark (kW per ton per horizontal length + vertical length) for all materials and appropriate conveying systems might be rather complex and tricky to use without the required detailed understanding of the materials and the conveying systems.

If you want to compare the energy consumption of conveying systems, ask the experienced system suppliers.

Have a nice day

Teus ■

Dear Sir,

A rule of thumb for judging the motor kW is given in CEMA 6th edition:

Effective tension Te less than or equal to Wm x H + 0.04 x (2 x Wb + Wm ) x L

Absorbed power= Te x Belt velocity/ drive efficiency (can be assumed to be 0.9 as for a typical motor fluid coupling gear box drive)

Thanks & Regards

Jishnu V

Engineer

BHEL-ISG ■

A rule of thumb as per CEMA 6th edition to calculate the effective tension is Te(in N) less than or equal to Wm x H + 0.04 x (2 x Wb + Wm ) x L

L= Length of conveyor (pulley shafts C-C distance) in m

H= Lift of conveyor in m

Wb= Unit weight of belt in kg/m

Wm= Unit weight of material= (TPH /Belt velcoity/3.6) kg/m

Power= Te x Belt velocity/ drive efficiency (can be assumed as 0.9 for a typical motor-fluid coupling-gearbox drive)

Thanks & Regards

Jishnu V

Engineer

BHEL ISG ■

I believe the thread starter has been in the business for some years and should know:

1. kW due gravity is well known lift x mass to lift

2. kW due to rubber rheology has been published in this form since 1990's over and over again

3. kW due to: belt cover thickness, belt mass, idler spacing, idler diameter, trough shape, lubricant, seal drag, and influence ditto item 2.

4. kW due to conveyor capacity, i.e. power is dependent on tonnage conveyed. If it is only one ton, who would build it? If one of many tons, kW is dependent on indention force (tons) which leads to a rhetorical question - how many tons

5. kW is dependent on operating/ambient temperature which you know

6. and so on - so what is the purpose of the question? I do not get your meaning and reasoning. I believe you know the answer is very complex and tedious with a wide range of results, and can not be covered in this forum with usable details. ■

Originally Posted by Roland Heilmann

to be frank, I came across such "number" twice, first it was the dream of some salespeople who yesterday sold peanuts and today were the bees knees of the bulk material systems market. There's usually nobody of a technical background involved, or heard, at that.

Second time it was when some maintenance people got the steering position in a newbuilt project and were, without any hesitation, comparing this conveyor A in this port with that conveyor B in that mine and concluding that their own project had to be A+B & frills on top.

It's the kind of question evolution was invented for. I do think of the engineers who will be "let go" because of the underlying implication of such reasoning: (expensive) professional detail input doesn't matter anymore, there's a simple "number", all in.

A !Thank you! nevertheless to all colleagues who gave technical input, to the technical = substantial side of the issue, if taken professionally.

Regards

R.

============================

Yes Roland,

I have met the same salesman. He told me all conveyors can be designed on the back of an envelop with all humility. It is what they do not care to know that inhibits our future. ■