Capacity is the product of speed & carrying cross section. Cross section is usually the sum of the trapezia formed by the troughing idlers plus a segment formed by material surcharge. (If you are talking troughed belt conveyors.) Then there is an added edge clearance of 50mm per side for spillage limitation.

It is more convenient, for manual calculation, to select a belt width & calculate its carrying cross section. Most design handbooks contain tabular values of cross section area for standard belt widths & troughing angles.

Depending on the conveying length & the material handled the surcharge can be seriously disturbed by agitation as the burden encounters the idler rollers; so modify the book values of surcharge accordingly. ■

Dear Shri Sunil,

The earlier respondent has already explained in detail about the fundamental consideration in deciding the belt width. Please also see that the belt width so decided should be wide enough to deal with the material lump size. There is enough of literature, you can refer to the relevant literature about deciding the belt width.

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 25882916 ■

Further to earlier (all correct) replies, please note that the inclination of the conveyor system will also have an effect on the capacity as it effects the surcharge angle, so the steeper the conveyor, the more of a reduction in surcharge angle.

But, the surcharge angle is also dependant on the friction between the belt and material, and how the material is loaded.

Stan Holcroft,

Regional sales manager,

Fenner Dunlop B. V.,

Netherlands,

+31 512 585 565

+31 620 49 88 29 mob) ■

Dear Sunil,

Let me simplefy you with example.

Q=3600 xA XV X B X 0.8 X In T/Hr

Say for 1000 mm belt

Material ... Coal

Bulk Density.. B= 0.8 T/Cub. m

Belt speed ...V= 2.0 m/sec

A = Sectional area of trough belt , 0.111 m. sq. given in ISO-5048 against 35 deg. at 20 deg surcharg angle

Troughing angle= 35 deg.

In = Inclination factor depends on conveyor angle

= 0.93 against 10 deg. conveyor inclination.

0.8 = Loading factor

THEN Q = 3600 x0.111x 2.0 x 0.8 x 0.8X0.92 t/hr

=470.5t/hr.

If your requirement is 400 t/hr then the above is OK. But you have to check with lump size factor.

Belt width = 4x Lump size

Regards.,

A.Banerjee ■

Often overlooked is the amount of edge distance required for effective sealing at the load zone. Allowing for sufficient edge distance outside the load chute will compensate for belt camber, crooked splice. and tracking problems. Much cleaner transfer points will be realized with a minimum 4" to 6" of free edge distance. This would be in addition to the calculated width required to carry the load.

Also be conservative on the bulk density used to calculate the load. The material is in a dynamic state and often the bulk density is somewhat less than publish data due to aeration of the conveyed materials. ■

And don't forget that the de-rating for inclination only really applies to the angle of the conveyor when you load it.

For example.. if you load an overland conveyor on the horizontal, you don't have to worry if it goes to 10 degree slope over a rail crossing or whatever. In practice the slope..once the belt is loaded..makes no difference. Its the same as a loaded coal truck. The load hardly moves despite the hills. (See previous thread on this one)

LSL Tekpro ■

Not so Mr. Spriggs,

Given a horizontal conveyor has the nominated or measured surcharge, the the incline conveyor will have two criteria for stable transport.

1. As you say the trailing end of a loaded section has a definite observable stability angle that reduces with increasing incline angle.

2. In addition, assuming a continuous loading, when you do a 3-D arrangement of the incline belt that is given a crossection of a horizontal conveyor, you will find a new rilling angle. If you cut a plane vertical to earth, at the incline crossection tilted where they meet at the apex or top of the surcharge shape, this new angle is the path the rock will roll down and not the horizontal cut plane. Check out the angle it makes wrt the surcharge angle assumed.

Cheers ■