Summary
This literature survey focusses on the overview and characteristics of belt conveyor systems and its applications. To further limit the analysis only single flight conveyors are taken into account, which are longer than 1000 meters. Furthermore they have to be of the troughed 3-roll type. A func-tional limitation is that projects of the 1970s and onward are included. The belt conveyor is under continuous improvement, in the recent years most attention is given to the energy efficiency of belt conveyors. The result for the drive train is the use of variable speed motors, that use less energy when the required capacity is low. Besides this some first steps are taken in the field of energy recovery systems for the bulk material. The belts are produced with high strength materials such as aramid, both for the reinforcing carcass as the rubber covers. When looking at the idlers the material of the rollers is altered to give low friction resistance, the wing rollers are split into two pieces to lower the rotating inertia and load dependent garland idlers are used.
This focus on the energy efficiency can be seen from the analysis of belt conveyor systems of the last four decades. The length of the systems has increased, while the power remained constant; they have become more effi-cient. Furthermore the average belt speed has risen also, the recent belt con-veyor operate at higher speeds than the older ones. The maximum strength of the belts has increased over the course of the years, but not that dramatic. In the 1980s belts of 7000 mmN were used, the nowadays this is 7800 mmN . Although the overall trend is that the average belt strength is decreasing. The transport efficiency of a belt conveyor system can be calculated using the DIN friction factor and the loss factor of transport. The difference between the two is that the second takes the mass of the load into account, the first the masses of idlers and belt too. Because of this difference the value of the loss factor of transport is a factor 2 higher that the DIN friction factor. The analysis shows that both efficiencies are decreasing in time. Thus the more recent belt conveyor systems are more energy efficient. The transport efficiency compared to the conveyor length is analysed too. The trend of this graph shows that a longer belt conveyor is more efficient.
