Dear Mr. Bill Potma,

Possibly you are referring to belt feeder cum conveyor i.e. at loading point it works like belt feeder, but beyond skirt board material is resting against the trough belt side only without skirt board (the belt is wide enough for this purpose). There can be belt weigher (scale) in portion without skirt board, so that it can give correct indication / signal of flow rate.

The drive unit should have variable speed. Its speed will adjust in accordance with weigher signal, and thereby will tend to maintain the set value of flow rate. This equipment has discharge control response with minimum time lag, whereas vibrating feeder discharge control will have delayed response as it will be using signal from subsequent conveyor, to control its discharge rate. This will result in lesser accuracy on discharge control.

The speed 1 mps is somewhat high. For a material like coal, the maximum speed of 0.6 to 0.7 mps will be more desirable.

Regards,

Ishwar G Mulani.

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

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

The operating characteristics of belt feeders has far more to do with the design of the hopper than that of the belt, particularly where long slots are concerned. It is good practice to extract from the whole length of the slot and also provide a inclined transition of the line of convergence from the supply hopper. In the case of very long outlet slots there is often virtue in using intermediate flow inserts to make the extraction profile more efficient and, for wide outlets or large installations, employing longitudinal inserts or slanting outlet connections to reduce the forces acting on the belt.

If the bins are existing, it is an interesting exercise to develop an optimum design. Brute force is generally not a good solution as it can be expensive on power and maintenance. ■

Dear Mr.Bill,

Speed of feeder is high. We restrict the speed upto 0.55m/s.Can you not reduce the speed?

Regards.

A.Banerjee ■

Dear sir

can you tell me why speed is restricted to 0.6 m/sec or less. I have rovided several belt feeders having speed around 1.0 to 1.2 m/sec.

A R SINGH ■

0.6m/sec seems to be an old hands rule of thumb.

Higher speeds mean higher wear.

Assuming feed from a charged bin, should not be too many issues.

Slot width to be greater than arching dimension

Slot length to slot width to be around 3.

Slot opening to taper 3deg. if possible.

Shear gate to be located right at the slot opening.

Skirts on belt to be vertical.

Skirt sealing design to cater for load pressure...may need inner/outer.

Feeder should be horizontal.

Consider belt carry back spillage and clean up.

Consider belt replacement and resplicing eg have on trolley wheels.

Drive to be electro/mech., simple shaft mounted with torque arm.

For variable speed, consider motor size/heating and also material trajectory.

Feeder power to consider pull out loads and also after filling of bin after been empty...compatction and consolidations pressures.

Consider haz. area classification and zoning

Cheers

James ■

Dear Mr. Singh,

Mr. Bill wants to install belt feeder below the bunker. You have installed many belt feeder with speed of 1.2m/s.I do not think those are under column load & not shearing the material.Please review.

Regards.

A.Banerjee ■

DEAR Bill Potma

PL SEND ME DETAIL OF BUNKER INDICATING TOP /BOTTOM OPENING ,HEIGHT OF BUNKER, LOADING ARRANGEMENT OF COAL TO BUNKER.ME.

I WILL REVIEW AND FURNISH SOLUTION OF SAME

A R SINGH

modtech@modtechprojects.com ■