Originally Posted by sathish.hariharan

Dear Experts,

In one of the enquiry, client has proposed to have a 3.5 m/s speed belt feeder(2000 TPH coal, -200 mm Lump)below silo to extract material. Please advise on its feasibility.

Best regards,

Sathish

They must be kidding.

If you are trying to discharge a load out of a silo with a belt feeder I would be looking at a speed closer to 0.5 m/s. At 3.5 m/s I have to ask if they have an interest in a belt supply company They will spend more time replacing the belt than feeding.

I am still trying to wrap my head around the image of trying to start the feeder with a full head of material on the belt. The smell of burning rubber... ■

Hi Sathish..

I normally go up to 0.75m/second for belt feeders.

We are however doing two of them right now that can go up to 1.2m/sec for minus 50mm coal under a 10 000 ton silo. I think this is a bit fast (but the client has specified this) but 3.5m/second for minus 200mm is really not on.

I have however, seen chutes under storage fitted with radial gates feeding onto conveyors at normal conveyor speed, (but these conveyors can hardly be called belt feeders).

Cheers

LSL Tekpro ■

Originally Posted by sathish.hariharan

Dear Experts,

Other than early wear of Top cover, what else is the negative effect of high speed ( > 1 m/s) in belt feeders?

Regards,

Sathish

There is fire, and then motor power, acceleration of the belt to speed. Not only will you experience wear of the top cover, but also the bottom cover as it slips on the drive pulley.

There will also be issues with tracking the belt. Really, you need to let your client know these things and give them an opportunity to change their mind.

A while back I posted a message on high speed belts and how you could get lower power and tension by running the belt at high speed, only not advisable to hurl -600 mm lumps at 4.5 m/s off the end of a conveyor. The difference between a belt conveyor and a belt feeder is the load acts completely differently. It is simply not the best design to have a belt feeder run that fast. ■

Hello Sathish,

I work at EMO bulkterminal in Rotterdam.

We have 6 silo's from where we extract coal. The beltspeed of the extractionbelts is variabl from 0 uo to 2.2 m/sec.They are 1600 mm wide

They drop their coal on a larger belt,1800 mm, that runs 4.5 m/sec.

regards

Harry ■

Originally Posted by polleke

Hello Sathish,

I work at EMO bulkterminal in Rotterdam.

We have 6 silo's from where we extract coal. The beltspeed of the extractionbelts is variabl from 0 uo to 2.2 m/sec.They are 1600 mm wide

They drop their coal on a larger belt,1800 mm, that runs 4.5 m/sec.

regards

Harry

But are they belt feeders?

Typically the belt feeder will have a feed opening many times the width of the belt, whereas a feeder belt (just a conveyor) will have a feed opening that be just around the width of the belt. Also a belt feeder will have a substantial part of the weight of the material in the bin or silo it is feeding from on the belt itself, as opposed to being fed via a chute.

The concerns expressed have to do with these issues.

As with everything, it is up to the engineer designing the piece of equipment. A client might request a particular type of conveyor, however it is up to the engineer designing the conveyor to advise their client of the potential problems. ■

You can run faster, but at a price of belt wear and power as others have noted.

We have successfully used ROCKY DEM code to quantify the wear and power. The critical non-commercial value is the efficiency of reclaiming at higher speeds. Most Belt Feeder withdrawal chutes are very poorly designed for efficient flow.

You must reclaim material from the feeder bottom configuration from the feeder back end to establish a product bed that does not slide on the belt. If you reclaim from the feeder front opening, you drag all the material from the feeder back end across the belt, exxagerating the belt wear rate, aside from the feeder speed.

This is one reason operators wish not to run a high speed. Its not just the proportion of wear to belt speed. Probably better than 90% of belt feeder chutes are improperly designed, causing higher cost of power and belt replacements.

We are willing to show these details to interested parties. Otherwise, buy ROCKY and do the tests yourself. ■

Incidentally.

There is comment above concerning belt wear.

Having visited about 15 feeder installations in various parts of the world while I was perfecting our feeder design, I can say that wear does not seem to be a problem... except:

Its the non-tapering skirts and non-flaring chutes that cause localised wear.

I have seen parallel skirts that have gone a long way to cutting the feeder belt into three in both Israel and Chile.

I have also seen a feed chute on iron ore not tapering upwards and outwards enough, and it completely destroyed the belt in a couple of weeks... so..

Speed is important.. but its the design that matters too.

Cheers

LSL Tekpro ■

Dear Shri Sathish,

One needs to be clear about the difference between belt conveyor and belt feeder.

1) In case of conveyor, there is no static head of the material on belt (the material is not resting on belt and then extracted). The material is freely falling on to belt at feed point. Slow speed conveyor with full length skirt board is often mentioned as a belt feeder by the decision maker of the name and it continues that way creating misunderstanding.

2) In case of belt feeder, there is static head of material on belt (the material is resting / pressing on belt and then it is extracted).

There are well defined rules for the belt speed of conveyors and the belt speed of belt feeders. One can infringe these established rules across the world. I do not subscribe to this approach.

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.

Pune, India.

Tel.: 0091 (0)20 25871916

Email: parimul@pn2.vsnl.net.in ■