Re: Tripping Of Stacker Boom Conveyor
Another Idea:
The tail drive produces (T2) carry side slack belt after and near the tail loading station, during higher power sequences of loading, as you described. I wonder where you have the takeup and what kind of control do you have for it?
The slack belt causes two main increases in rolling loss factors. The slack or sag causes the product to relax in between the idler spacing and then forced back into the idler trough shape at each idler. This loss is often called a trampling loss. As the belt is flexed over this same belt route, the low tension belt zone will experience an increase in flexure of the belt rubber/ fabric / steel which will also consume power and is refered to as the flexion or flexural loss and is a rubber and fabric or steel viscoelastic hysteresis power loss.
One way not suggested is to place a gravity or hydraulic take-up after the tail drive on the belt carry strand. This would be similar to our design of the 16 km ZISCO overland in Zimbabwe. See our website:
a) http://www.conveyor-dynamics.com/about/dynamics.htm
b) http://www.conveyor-dynamics.com/about/curvedex.htm
Yours will not be this complex. This concept controls the initial carry side tension to a constant value that is sufficient to pull the conveyor without drive slip and with sufficient minimum tension for your selection of sag or slack belt control. It meets your noted criteria of insuring minimum and proper tension at all times and for all loads.
Hydraulics can be used. It may be slightly cheaper than a gravity counterweight, but it will be less reliable and have greater risk of failure than the gravity cwt, and probably less control of the minimum tension without slip.
You can add your second drive as you note at the tripper head or you may save money and other conveniences by placing a second drive pulley at the tail. It will take a little review to see that it is the belt solution.
Regards,
Lawrence Nordell
website: www.conveyor-dynamics.com ■
Tripping Of Stacker Boom Conveyor
Dear Mr. Nordell,
Thanks for the response. I am furnishing the following information of the Stacker, for better understanding of the problem:
Stacking capacity : 800 TPH (Normal) /1000 TPH( Design) I/Ore
Reclaiming Capacity : 600 TPH( Normal)/ 800 TPH( Design)
Stock Pile Ht. : 10 mtrs from GL.
Boom Conveyor - Bw - 1000 mm, Speed - 2 m/sec.
Boom luffing angle : - 10.5 deg to + 9 Deg.
Pulley Crs - 40 mtrs. Boom Reach - 38.5 Mtrs.
Location of Drive Pulley dia 630 mm - at Tripper, take up - at Discharge Pulley (Screw Take up - travel 500 mm), High Speed coupling - Fluid Coupling.
Tripper :
Belt width - 800 mm, Speed - originally 2.5 m/sec ( increased to 3 m/sec by changing the drive pulley from 800 mm to 1000 mm), Capacity 800 TPH Original, 1000 TPH revised.
There is no space at Tripper end of Boom conveyor for Second Drive Pulley. The space is also not available at Discharge end of Boom Conveyor due to Bucket wheel & it's drive.
There is no space for a Gravity Take up.
With above information, can you make specific specific suggestions.
Regards ■
Re: Tripping Of Stacker Boom Conveyor
This can be a common probelm, U did not say what the tripping actuallt was due to:
motor overlaod
belt underspeed.
Do not add a counterweight at the head end...U will effect stability.
I assume that U have a 2 , 3 or 4 pulley system...there should be a snubber pulley close to the drive to help with T1/T2 and belt tension.
If U have belt slippage and belt underspeed, then increase the screw tension.....U can work out what amount by doing some simple sums...in order not to over stretch the belt nor overlaod components.
Consider adding more impact idlers at load zone or impact table for better belt supports to stop materil jamming under skirts
If U have overlaod, then U need to look at the situation wrt motor and possible feed to the belt itself...
Do U have a deflector chute to direct the material forward and along the belt...is it possible to fit this.??
Is the stacker moving when forming ie chevron stacking -do U get overlaods when the stacker is travelling into the belt direction??
The above shoudl give U some pointers acc.
Cheers
James ■
Re: Tripping Of Stacker Boom Conveyor
Rekhawar:
First, the drive I was refering to was per you comment of a motorized boom discharge pulley.
Second, post or email the conveyor dimensional arrangement details. Then we can make an informed comment. There are many ways to increase the ability to drive this system. Upon seeing the actual working details, you can receive the best advise.
Lawrence Nordell
www.conveyor-dynamics.com ■
Tripping Of Stacker Boom Conveyor
Dear all,
Thanks for all your responses. After going through your posts, I find that adding a second drive i.e. motorised pulley at discharge end will solve the problem. This is because basically we want to increase the conveying capacity of the boom conveyor.
First of all, let me clear that there are only 2 pulleys in the Boom conveyor. First - Tail cum Drive pulley mounted at Tripper and second - Head cum discharge pulley mounted at Boom end.
Now suppose the existing Boom Conveyor drive motor is 30 kW, than shall the additional motorised pulley also be 30 kW? .
We are only supporting the main existing drive, with this logic a 10 kW motor will also do the job.
The tail end drive is with fluid coupling, hence in case of any jamming at tail end, the new drive at the discharge end shall be able to take the full load. with this logic we have to have a 30 kW
motorised pulley.
How to select a proper motorised pulley at Discharge end? Boom conveyor is a reversible conveyor. Can a motorised pulley provides power in both the direction?
Obviously the output rpm of motorised shall match with belt speed of the conveyor.
Hope I am able to explain the issue clearly.
Regards ■
Tripping Of Stacker Boom Conveyor
Dear all,
I have more or less zeroed on for the solution, however I am yet to be cleared on following issues:
1. What shall be kW of new motorised pulley? It shall be less than the existing drive or equal to it? Cost sensitive, as the existing drive is 55 kW.
2. Can motorised pulley provide power in both the direction? can it run idle?
I hope to get good response from you.
Reagrds ■
Re: Tripping Of Stacker Boom Conveyor
REKHAWAR
You have a number of potential problems in the manner you have setforth in your discussion. I fear you have not studied the engineering detail correctly.
For one, you need to study the speed compatability.
Lawrence Nordell
www.conveyor-dynamics.com ■
Re: Tripping Of Stacker Boom Conveyor
Dear Mr. Rekhawar,
The boom conveyor or any other conveyor can trip according to the various monitoring switches forming a part of the system, such as
- Overload trip switch (as the name signifies, it will stop the conveyor if the load is excessive)
- Zero speed switch i.e. belt monitoring switch (this will stop the conveyor if it fails to reach the required speed within preset time during starting or it will also trip the conveyor if there is a slip between the belt and drive pulley).
- Belt sway switch (If the belt runs mis-aligned beyond the permitted limits).
- Load monitoring switch in the take-up, if applicable.
- The signal from any other equipment or switch which is controlling the conveyor operation in a certain situation (such as chute blockage switch or high level switch in bunker etc).
Therefore, to prevent the frequent tripping of boom conveyor, find out the source and one has to take the remedial action accordingly.
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 ■
Tripping of Stacker Boom Conveyor
Dear friends,
We have a Stacker cum reclaimer in our yard. The problem, we are facing is frequent tripping of Boom Conveyor Drive due to overload, mostly when stacking at higher luffing angle i.e. at high stock pile height.
Our observations are as follows :
1. The conveyor is tail driven, when in stacking mode. The belt at loading point gets slackened causing belt getting squeezed at Impact zone, hence the tripping.
2. The tripping increased recently when we laid a new belt The tightening of screw take up done as and when belt found loose, however the problem persists.
3. The problem is more frequent with Iron ore pellets, in which the flow control is difficult, hence over TPH occurs. We are in a process to install a motorised get below hopper to regulate the flow.
The reason for Tripping is quite obvious i.e. Over TPH. My point is Boom Conveyor has become weakest link in our whole Stacking route. If we overcome the tripping problem, the conveying capacity of whole route will increase.
I want your comments based on practical experience on following ideas:
1. Installing Hydraulic Take up in Boom Conveyor, to ensure proper tension of belt all the time.
2. If we install a motorised pulley at the Boom Conveyor Discharge end which will run in synchronized way with existing drive, than Drive power will increase and tripping can be arrested.
Kindly suggest if any other better solution is available. ■