Residuals Removal at Maritza E1

Tube Conveyor Systems

Residuals Removal at Maritza E1

Design, Installation and Commissioning of a Tube Belt Conveyor
With the reconstruction of the power station Maritza East 1, the residual materials disposal system has also been reorganized. This project was contracted to Takraf in 2006. The heart of the residual material transportation system is a 4.5 km tube conveyor that follows the course of an old railway line and was realized in cooperation with ContiTech.
(ed. WoMaMarcel - 09/12/2014)
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5    Commissioning

Commissioning of the Maritza tube conveyor took place in the spring of 2010. Similar to the process of pulling in the belt, the tube belt was carefully monitored at the critical points during commissioning (particularly in curved sections and the flat-to-troughed and troughed-to-flat transition zones). The commissioning process for a tube belt system is normally accompanied by very high running resistances, which are caused by high form forces during the run-in period of the tube belt and by high friction forces in the overlapping area. As a result, an increased power demand needs to be taken into account when designing the drive power of the conveyor system.

In order to reduce the high friction forces in the belt overlap, a sliding additive (e.g. talcum powder) was added in the belt overlapping zone. Corrective measures were immediately put in place if the tube belt displayed any twisting (Fig. 18).

6    Power Consumption

Following an approximately 6-month test operation – a time span resulting from the start-up cycle of the power plant – measurements were taken to determine the power consumption of the TC-3A.

At peak throughputs of 1000 t/h, the power plant was able to provide a maximum average loading of the entire conveyor length of approx. 700 t/h. Fig. 19 shows the individual measurements as measuring points to which a trend line was added.

Of particular note here is that there is no significant difference between idle power and the driving power of the loaded belt. If the fictitious friction coefficient ƒ is calculated back from the individual measurements, the following image results in Fig. 20.

Idling gives rise to a fictitious friction coefficient that significantly exceeds the value for the loaded belt. This is caused by the aforementioned additional components of main resistance. These are largely independent of the loading state and determined primarily by the belt properties.

The design of the tube conveyor must take this effect into account. Particularly for small throughputs and/or conveyor goods with small bulk densities, the idle behavior of the conveyor belt largely determines the power requirement.

The conveyor belt was designed, as described above, with a fictitious friction coefficient of ƒ = 0.043. When the trend line shown above is extended to the finally estimated throughput of 1400 t/h, a fictitious friction coefficient of around 0.044 results. This is affirmation of the installed driving power of 2000 kW.

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