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October 15, 2017

16/10/2017: Detecting and preventing bucket elevator failure

by Maxi-Tronic, Loveland, Ohio, USA

In 2016 a commercial grain elevator in central Ohio USA was unintentionally shut down due to an equipment failure during the grain harvest

The cause of failure could have been easily prevented. The results of the failure were a calamity. The cause of the failure was a belt burned in two in a 20,000 BPH [508 MTPH] main receiving elevator.
 


Apparently, the belt started slipping on the elevator head pulley. Friction burned the belt in two, dropping half of the belt and buckets down each side of the elevator casing. The buckets on the up side were all full of grain.

The elevator was inside of a jump-formed concrete storage facility. Fortunately, the friction of the pulley burning through the belt did not initiate a fire or dust explosion, which would have been catastrophic.

The elevator is located adjacent to the railroad tracks on the edge of the central business district of a medium sized town. An explosion in that location would have had a high probability of fatalities, serious injuries, and major property damage to the elevator and surrounding businesses.

At 20,000 BPH/508 MTPH the elevator utilised a very wide belt and multiple rows of elevator cups. To repair the elevator the head cap was removed and man was lowered by crane into the elevator casing to retrieve the burned tail end of the elevator belt – a hazardous operation at best.

Belt for a repair splice was not immediately available, leading to delayed repairs. The elevator was out of operation for more than two days while their customers transported their harvest to competitors.

The cost of service trucks, labour, crane, equipment, and materials ran more than US$20,000 [over €17,500] not counting the loss of business. The real tragedy is that for far less money the situation could have been fully prevented.

The slippage of a belt in a bucket elevator is not uncommon. It can be caused by a belt under inadequate tension, worn head pulley lagging, a plugged elevator, condensation, a frozen belt, or a combination of conditions.

Detection and prevention of a failure condition is very easily achieved with a simple monitoring device, which alerts immediately when the elevator boot pulley begins to travel 10 percent slower than the elevator head pulley.

At 10 percent slow down the motion control system can sound a warning alarm and turn off any conveyors feeding the bucket elevator. At 20 percent slow down the monitor will turn off the power to the bucket elevator preventing the scenario described above.

In the United States, installation of motion control system is required by federal regulations in any facility, which has a storage capacity of 1,000,000 bushels [25,400 MT] or greater. Failure to install and maintain such a system is a violation subject to penalty.


Read the full article, HERE.

Visit the Maxi-Tronic website, HERE.
 

The Global Miller
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which is published by Perendale Publishers Limited.


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