Re: Drag Chain Feeder - Even Feeding
Chain/en-masse feeders are not ideally suited to bunker outlets with L/D greater than 3. Ratio's of 2 - 2.5 are better.
A divergence of 3 degrees in plan is insufficient even at L/D = 2 to get a drawdown from the whole length of the outlet, it should be significantly greater.
A well established feature of chain/en-masse feeders under long slot bunker outlets is to use transverse members to divide the outlet into sections, each transverse member allowing an increment of load to be added from each outlet section. Thus if you have two transverse members (plus the final load plate) each should add one third of the final load depth. Of course, if you have large lumps in the material, this arrangement can lead to jamming under the transverse members.
How well anything operates depends on the flow properties of the material handled. Your description " ... the coal will rills out pasts the slot walls ..." would indicate quite a dry product. ■
Re: Drag Chain Feeder - Even Feeding
Dear Mr. James Morrish,
Following points have some relevance to the performance of drag chain feeder:
1) Hopper outlet exit end opening size can affect performance.
2) How about the chain speed? Slower the speed better it is.
3) In the apron feeder / chain feeder / belt feeder, major flow occurs in zone near exit end of the outlet. Rear portion contributes less. It would be better if you mention the flow width and flow height as per chain & drag flight arrangement. Also the outlet opening length.
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 ■
Drag Chain Feeder - Even Feeding
Hi All,
We have on a raw coal bin and drag chain feeder.
The bin was very steep walls leading to a slot opening L/D> 3 and the slot opening is tapered at a small angle..est 3 degrees.
The coal drag chain feeder is a simple forged chain type with the chains almost at the full width - there are short extension bars on the chains on both sides of the links.
The outer bars reach the full width of the slot/chain casing.
The inner bars are used to attach the scraper bars which are in between the 2 chain strands.
The feeder does not make the coal draw down evenly in the raw coal bin.....rather draw from the end (as per usual)...as a result, we get coal slips in the bin with a small amount of structural vibration as the coal slips.
I have looked at trying to make the feeder act as a tapered feeder.
The problem is that the coal will rills out pasts the slot walls to fill up the space in between each drag bar...hence, the chain becomes full very close to the feed end...
Any suggestioins on how not to fill up the drag chain at the start of the slot hopper and make is draw down more evenly.
Another thought is to use inverted V shedders to break up the slot into 2 or 3 smaller slots...
Comments pls.
Thanks
James Morrish ■