Thread by @chrisyelland

Following major problems that brought Medupi power station to its knees during the height of the loadshedding last week, Medupi power station manager Rudi van der Walt has been forced to step down and be replaced immediately, pending his departure from @Eskom_SA and SA shortly.

@Eskom_SA Other staff at Medupi have been dismissed by @Eskom_SA generation head Bheki Nxumalo for negligence in what Eskom COO Jan Oberholzer calls "consequence management" following a number of major problems at Medupi that contributed to the loadshedding last week.

@Eskom_SA A number of additional problems at Medupi power station have now been identified that have not been previously disclosed to the public by @Eskom_SA's management, while Medupi and Kusile are emerging as major threats to the adequacy of the power system to meet demand in SA.

@Eskom_SA For some time, the stackers that load coal from Exxaro's Grootegeluk mine onto the stockpiles at the Medupi coal stockyard at Medupi, and the reclaimers that take coal from the stockpiles to feed coal by conveyor to the power station boilers, have not been working.

@Eskom_SA So to get coal to the Medupi boilers, the coal stockyard was bypassed, & the single main coal conveyor feed from Grootegeluk was feeding the power station directly, without any redundancy in the system. So, effectively, Medupi was running with minimal coal stock at its disposal.

@Eskom_SA Thus when the single main coal conveyor feed from the Grootegeluk mine failed on the @Eskom_SA side with a broken belt, Medupi was left with no coal feeding its boilers other than about 1 or 2 shifts worth the coal in the bunkers feeding each boiler.

@Eskom_SA To add to the disaster, it is now clear that blocked chute and belt rip detectors were not working, so the conveyor did not trip when it should have done so in order to protect the system, thus causing damage to some 700 m of belt, and damage to the conveyor structures.

@Eskom_SA With the main coal conveyor from Grootegeluk mine not working, & the stacker/reclaimers at the Medupi stockyard not working, coal now had to be transported by truck from the stockyard, for offloading at the emergency Buffalo conveyors at the bunkers to get coal into the boilers.

@Eskom_SA This was a major logistical nightmare due to the huge volumes of coal involved. Major congestion of coal trucks transporting coal from the stockyard to the bunkers caused the power output of Medupi to be reduced to 1/3 of normal, thus contributing to loadshedding.

@Eskom_SA Then problems were experienced with the ash handling plant which conveys ash from coal that is burned in the boilers. Staff working on the bunker feed problems were thus shifted to deal with a huge build-up of ash, thus compounding the problems.

@Eskom_SA The good news is that the main coal conveyor from Grootegeluk mine is expected to be operating again shortly, thus relieving the logistical problem of transporting coal by truck & manually offloading the coal at the emergency Buffalo conveyors to feed to the boiler bunkers.

@Eskom_SA The bad news is the stacker/reclaimers are still not working. So, with the coal stockyard bypassed, Medupi remains vulnerable and dependent on a single, long, conveyor feed from Grootegeluk, without any redundancy if the conveyor should fail or trip for whatever reason.

@Eskom_SA To summarise the known problems at Medupi:

1. The main coal conveyor feeding coal from Grootegeluk faied with belt and structural damage.

2. Protection devices on the main coal conveyor failed to detect the fault timeously.

... (cont)

@Eskom_SA ''' (cont)

3. The stacker/reclaimers at the Medupi coal stockyard are not working, this the coal stockyard is bypassed.

4. Coal was been transported by truck from the stockyard to the boiler bunkers causing massive congestion and reducing output of the generators.

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@Eskom_SA ... (cont)

4. The coal mills are of wrong design, causing excessive wear & tear, & increased maintenance & downtime.

5. The design height of the boilers is inadequate (too low), causing excessive temperatures within the boiler & flue gas.

,...(cont)

@Eskom_SA ...(cont)

6. Excessive flue gas temperature is causing premature failure of the pulse-jet fabric filters (an essential fly ash collection & pollution control system).

7. The ash handling system is unable to cope with the volume of bottom ash & fly ash from the boilers.

(ends)