NALCO installs new ash disposal system in Power Plant at Orissa's Anugul

Report by Orissa Diary correspondent; Bhubaneswar: National Aluminium Company Limited (NALCO), India's leading producer and exporter of alumina and aluminium has achieved yet another milestone in environment protection and reduction in pollution in their plant vicinity with the commissioning of HCSD System in its 1080 MW Captive Power Plant. The system is one of the latest and eco-friendly ways of Ash disposal of Modern Power plants, adopted by Nalco at a cost of Rs.50 cr.

The High Concentration Slurry Disposal (HCSD) System is designed to cater the requirement of Fly Ash disposal of Unit 7 to 10 of CPP. This system reduces ash pollution in the atmosphere, as there will not be fine ash dust in the ash pond, which gets blown off during wind. The other advantage of this system is that the fine ash in the form of lumps is discharged to the ash pond. Since the ash discharge is in the lump form, it occupies lesser space in the ash pond compared to the same volume of slurry ash in the ash pond, resulting in extension of the useful life of the ash pond. Fly ash from units 7 to 10 of CPP is collected in Dry form in 2 nos Fly Ash Silos, each of 1500 Cubic Mtrs capacity. Ash from the Fly Ash Silos is discharged via a Bin weighing system, Dosing valve feeder and an Ash Conditioner to the Agitated Retention Tank (ART). Water line to each of these unloading systems is also provided with flow transmitters. Water flow to the mixer is controlled through a control station to allow controlled amount of water into the system. One set of this equipment is provided below each Fly Ash Silo.

The ART is provided with an agitator to enable proper mix of fly ash and water to arrive at the right concentration of High concentration slurry for disposal. The concentrated slurry thus prepared in the ART is pumped through a Charge Pump to special High Concentration Slurry Disposal pumps. A control loop of instrumentation is provided across the ART to ensure that correct concentration of fly ash mix is pumped to meet the ultimate objective.

Three sets of such HCSD pumps (2 working + 1 standby) are provided, each with a discharge capacity of 160 m3/hr. The high concentrated slurry is deposited in Ash pond no- 1 & 2 via distribution piping, diverter valves and discharge lines located at suitable intervals.

The High Concentration Slurry Disposal pumps are supplied by M/s Weir Minerals, Netherlands.