...Pay Up or Shut Up!

Your client runs material too hot for the product, and then some: still gets 6 months out of a belt: refuses to do the job properly and has a problem!

Since the belt suppliers you mention cannot extend his belt life to a year, and they must have a point, it is reasonable to assume that your client must stick with what he has and improve his belt replacement time by e.g. having replacement belt in a well ventilated annexe as near as possible to his hotspot.

If you are prevented from using an armoured type of conveyor then your client is strictly at the mercy of the belt vendors, aren't we all? Why would a supplier charge a bit extra for a 1 year belt when he can charge twice for the durable belts which he supplies at present? R & D types will charge an arm and a leg while telling you they can match the requirement. So, why has no R & D solution been presented......maybe because there isn't one. Clearly your client is barking up the wrong tree! ■

John is right, there is not a rubber belt solution. What I would suggest is that you extend the belt backwards a little and feed onto it a layer of cold clinker to protect the belt surface. Cold clinker is a good insulator. You will need to look at the overall belt capacity but usually clinker belts are not highly loaded and such an option is far cheaper modification than replacing belts every 6 months. The cold clinker depth will need to be at least 20-30 cms

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Originally Posted by Umermukhtar

Dear Experts and Fellow Members,

Good Day.

I have been a silent spectator for the group for sometime now but now i am facing a problem that i require help on.

Our Cement client is facing problem in their clinker conveying due to some inherent problem in the cooler (note: Client isnt willing to spend huge sums for cooler fixing). The temperature of clinker transport from storage to grinding mills is around 320-350 DegreeC at constant, therefore they are facing severe belt failure problems. GoodYear, Dunlop, Barberri, SIG, Bridgeston and what not has been used but the belts fail within six months and lead to unexpected failures and sometimes stoppages. The belt is in six stages, covering a total distance around 700 meters therefore the costs of replacement are high as well. Kindly please suggest a solution or a rubber belt able to withstand around 350-400 DegreeC constant for around a year.

P.S Metallic belts are being planned but the initial costs are way too high and retrofit options are not working out as well due to high clinker loads of around 450t/h.

Alternatively, if any new innovative solution/ R&D is taking place in world, we would like to give it a try as well. Looking forward to your valuable inputs. Thanks!

Kind Regards,

Umer

Originally Posted by johngateley

...Pay Up or Shut Up!

Your client runs material too hot for the product, and then some: still gets 6 months out of a belt: refuses to do the job properly and has a problem!

Since the belt suppliers you mention cannot extend his belt life to a year, and they must have a point, it is reasonable to assume that your client must stick with what he has and improve his belt replacement time by e.g. having replacement belt in a well ventilated annexe as near as possible to his hotspot.

If you are prevented from using an armoured type of conveyor then your client is strictly at the mercy of the belt vendors, aren't we all? Why would a supplier charge a bit extra for a 1 year belt when he can charge twice for the durable belts which he supplies at present? R & D types will charge an arm and a leg while telling you they can match the requirement. So, why has no R & D solution been presented......maybe because there isn't one. Clearly your client is barking up the wrong tree!

Originally Posted by Colin Benjamin

John is right, there is not a rubber belt solution. What I would suggest is that you extend the belt backwards a little and feed onto it a layer of cold clinker to protect the belt surface. Cold clinker is a good insulator. You will need to look at the overall belt capacity but usually clinker belts are not highly loaded and such an option is far cheaper modification than replacing belts every 6 months. The cold clinker depth will need to be at least 20-30 cms

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com

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As John and Colin have explained it very well your issue is heat and then some more heat.

If the belt flight is linear in its entire path you have one useable option as a plow conveyor

would wear out too quickly.

As your production is 450 tons per hour an ideal method would be to use a narrow gauge

(36 inch rail guage) mine tunneling battery powered locomotive system with side dumping muck cars.

Unless you have room for a standard guage rail line with side dumping ballast cars. ■

Originally Posted by lzaharis

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As John and Colin have explained it very well your issue is heat and then some more heat.

If the belt flight is linear in its entire path you have one useable option as a plow conveyor

would wear out too quickly.

As your production is 450 tons per hour an ideal method would be to use a narrow gauge

(36 inch rail guage) mine tunneling battery powered locomotive system with side dumping muck cars.

Unless you have room for a standard guage rail line with side dumping ballast cars.

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I agree with Colin on his cold clinker fix, except the size and bed depth. I think he meant "30-40 mm" not "cm". This will take some effort to store and meter (passing size -25 mm x 0; with 40-50mm depth spread over the likely clinker width) ground material and feed it onto the main belt before hot clinker. Maybe, recycle the cold clinker belt-lining back on the return strand? Conveyor Dynamics, Inc. can do this. It is a bit of a twister, pun intended.

There are high temp belt constructions that have a upper spec. limit at 400 C. Can you post the belt spec you asked for? Maybe, there are better compounds.

There are metal belts (Sandvik), armor plate belts and possibly ceramic plated/impregnated belts that could handle the task as well.

Give a call if you wish more. ■

Hot clinker is being transferred from storage to mill. Isolation of cooler clinker would be admirable but costly seeing as how the entire conveyed product is destined for milling.

Aumund, aus Deutschland, for one, can supply an armoured, almost panzer type, conveyor which is highly suited to this application. It is also a case of buy now while stocks last because if this client is not prepared to rectify the cooler it is most likely that it will, sooner rather than later, fail completely and then he can either spend the money or shut down his rocky plant. I wish they were all so easy! ■

The exit of the clinker cooler is always a problem when plants expand and make more product the cooler no longer has the capacity to cool the clinker. If a larger fan can not be used due to air balance then maybe; Harleyville back when it was Lafarge and back before they upgraded their cooler used to keep a fire hose open on loading zone of clinker onto the belt. At the right flow clinker cools and water evaporates and you save your high temp belt for another day. ■

Harleyville had the good sense to upgrade the cooler after finding that producing more hot product input made the exigent flow hotter if the heat extraction remained the same. Not hard to understand that one.

What is not so easy to understand is how the emergency quenching reached the core of the hot product?

If the product throughput could be increased at will then there was an oversight in the original mass balance. They could handle more throughput with the original conveyor: they just forgot that extra cooling would be required. ■

Originally Posted by johngateley

Harleyville had the good sense to upgrade the cooler after finding that producing more hot product input made the exigent flow hotter if the heat extraction remained the same. Not hard to understand that one.

What is not so easy to understand is how the emergency quenching reached the core of the hot product?

If the product throughput could be increased at will then there was an oversight in the original mass balance. They could handle more throughput with the original conveyor: they just forgot that extra cooling would be required.

The core temperature was not important. All you need to do is lower the outer temperature enough so that you don't burn the rubber off the belt. If you vaporize 100#/min of water then you have removed that much energy from the clinker. The bucket elevator and concrete silo have no problems with hot clinker. ■

Hello,

Belt is made from rubber and nylon / polyester. So, it can not withstand high temperature like steel. Therefore, one has to opt for chain bucket conveyor for certain length, till the material has cooled down to usually permissible temperature for belt.

Option - 1: If belt failure is due to carcass weakening, then use of steel cord belt can improve situation somewhat. Such condition can be judged by indication that the belt is good externally, but suddenly it has snapped. Well there is apprehension that even in steel cord belt the vulcanised joint has rubber type material for withstanding the tension between two cords.

Option - 2: First conveying is by slow speed chain bucket conveyor of about 100 m length. Chain bucket conveyor is simply exposed to atmospheric air. In this case, calculate the temperature reduction of material, in manner mentioned for option - 3. If such natural cooling brings the material temperature sufficiently down, then the conveying beyond can be regular belt conveyors having HR belt.

Option - 3: Install chain bucket conveyor for initial conveying say over 100 m length. Reputed makes show such chain conveyor conveying red hot materials. Install this conveyor segment of say 20 m length in openable type enclosure, for circulating cold air at say minus 15 to minus 20 degree C air as counterflow to material motion. Keep the chain bucket conveyor speed slow say 20 m/minute so that it will give about 1 minute time for material to cool down and by that time air at outlet end might have already acquired 45 degree C temperature (it is of no use to have artificial cooling beyond this temperature which is freely available naturally). Install about such 2 to 3 units from discharge end side that is initial some portion can have natural cooling if need be.

One can calculate heat loss by conduction, radiation and convection:

- Heat loss from material by direct radiation to enclosure. Enclosure internal surface can be of black colour.

- Heat loss by conduction to raise temperature of carrying run bucket and chain (this bucket chain gets cooled during return travel).

- Expected heat flow from conveyor frame to cooling air.

Low speed as above of chain conveyor will make it bigger in size, but one has to pay for that. Cold air (refrigerator) system will also cost money but there is no other way to reduce the material temperature quickly. Heat loss by material is heat load for the cooling system, approximately.

Expected material temperature can be calculated at the discharge end of chain conveyor. Design the system such that this temperature is tolerable to belt as a regular feature.

To avoid downtime, install this chain conveyor very close to the existing belt conveyor. So, belt conveyor continues to operate till chain conveyor is ready for operation. Then make only feed and discharge chute connection, which will have insignificant downtime.

Ishwar G. Mulani

Author of Book: Engineering Science And Application Design For Belt Conveyors (new print November, 2012)

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: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

Hello,

In my earlier reply, please read following correction / clarification:

The cold air inflow would be at middle of enclosure's segment and hot air will come at both the ends, because both the ends are open due to conveyor. So, cooling by counterflow is not applicable (counterflow is possible to certain extent by creating pressure gradient by exhaust and inlet fans, but not worth).

The reply to be treated as basic concept, and user to analyse further.

Ishwar G. Mulani

Author of Book: Engineering Science And Application Design For Belt Conveyors (new print November, 2012)

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: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

This problem arose because the end user will not upgrade his cooler.

If he won't spend money to repair the cooler he is unlikely to agree to a major rework costing an arm and a leg. Cold air inflow is a bit of a non-starter since the cooler is inadequate in the very first instance. ■

Originally Posted by cementhead

...... used to keep a fire hose open on loading zone of clinker onto the belt.......

I trust they forgot to inform the local Fire Authority. Using a fire hose for anything other than fire fighting is illegal in most civilised countries and also invalidates the insurance cover. ■