Chris Geijs – Student werktuigbouwkunde wb9261549
Abstract
This literature study examines the possibility to place a beltfeeder system underneath the
Eurosilo concept.
In order to reclaim coal correctly from the Eurosilo concept, ESI Eurosilo used to place
Uncoalers underneath the silo. In some cases, it has been shown that Uncoalers are not
the correct reclaiming device to extract coal from the Eurosilo concept. The Red Hills
powerplant in the United States is a good example of reclaiming problems with
Uncoalers, due to flushing and bridging. Because of the problems with the Red Hills
powerplant, ESI Eurosilo was interested in obtaining more knowledge about the
belt/feeder reclaim system.
In order to create the right design for the hopper, underneath the silo and the beltfeeder,
knowledge has to be obtained for the flowproperties within the Eurosilo. Current
knowledge on calculations for flowproperties in silos, proved to be not sufficient for
determining the flowproperties within the Eurosilo. For this reason Eurosilo has to rely
on experience in practise, in order to determine parameters like the critical outlet
dimension from Eurosilo to subhopper.
The design of the belt/feeder system has to be approached as one integral system.
Without such an integral design to adjust the belt to subhopper, constant flow of reclaim
material can’t be guaranteed. The angle of the hopper side walls has to be chosen
carefully, in order to make sure that proper mass flow will occur along the slope walls.
The outletsurface of the subhopper has to increase along the beltfeeder, in order to
promote stable flow. In order to create a practical design, articles of Mr A.W. Roberts
proved to be usefull.
In order to create a proper design of the beltfeeder, calculations for the forces on the
beltfeeder are required. Calculations of these forces, while the system is idling, do not
represent practical values, due to the current known calculations for flowproperties in
silos, which can’t be used with the Eurosilo concept. Calculations for the system during
reclaiming of material, deliver practical values. With knowledge of these forces, the
needed power for the beltfeeder, in order to reclaim bulk material, can be determined.
The friction coefficient between bulk material and beltfeeder, gives information about if a
profile at the beltfeeder is needed, in order to obtain the no-slip situation.
The belt/feeder system is a possibility for replacing the Uncoaler as an extracting device.
One has to take into account though, that underneath the Eurosilo a large amount of space
is required to place such a system. This needed space, mostly needs to be underground,
which higher the costs for placing such a system.
Chris Geijs – Student werktuigbouwkunde wb9261549
1 Inleiding ... 2
1.1 De Eurosilo voor opslag van kolen... 2
1.2 Onderzoeksvraag ... 4
1.3 Opbouw van het rapport... 8
2 Ontwerpmethode voor de Eurosilo... 9
2.1 Vaststelling materiaaleigenschappen en silodimensies ... 9
2.2 Theorie en vaststelling van metingen, gedaan door BSE ... 11
2.3 Berekeningen aan stromingskanaal en schachtdiameter ... 15
2.3.1 Benadering voor de functie G(Ø)... 15
2.3.2 Berekening van de consolidatiespanning in de Eurosilo... 16
2.3.3 Berekening “upper bound” kritische schachtdiameter... 17
2.3.4 Berekening “lower bound” kritische schachtdiameter... 18
2.3.5 Berekening “lower bound” met tijdsconsolidatie... 20
2.3.6 Berekening diameter uitstroomopening van de Eurosilo... 21
2.4 Resultaten rekenmodel en conclusies voor Eurosilo ... 24
3 Hopper voor transport van Eurosilo naar transportband... 25
3.1 De functie van een subhopper ... 25
3.2 Positionering van de subhopper onder de Eurosilo ... 26
3.3 Theoretische opzet voor dimensionering van de subhopper ... 29
3.4 Dimensionering van de subhopper... 36
3.5 Resultaten rekenmodel en conclusies voor subhopper ... 40
4 Transportband voor reclaimen van stortgoed ... 42
4.1 Functie van transportband en criteria voor goede werking ... 42
4.2 Berekeningen aan verticale krachten op de uittrekband ... 44
4.3 Benodigd vermogen voor het reclaimen van stortgoed... 47
4.3.1 Vaststellen van criteria die het vermogen bepalen... 47
4.3.2 Benodigde kracht voor afschuiven stortgoed... 47
4.3.3 Kracht door weerstand side skirts... 48
4.3.4 Weerstand geladen transportband tijdens bedrijf... 49
4.3.5 Bepaling totaal benodigde vermogen... 49
4.4 Benodigde bandfrictie ter voorkoming van slip ... 50
4.5 Slijtage en onderhoud... 52
4.6 Resultaten rekenmodel en conclusies voor de belt feeder ... 53
5 Conclusies en aanbevelingen ... 54 5.1 Conclusies ... 54 5.2 Aanbevelingen... 57 Literatuurlijst... 58 Bijlagen ... 59 Bijlage 1 ... 59 Bijlage 2 ... 60
