KARACHI, Oct 29: Load-shedding persisted across the city for another day as the Karachi Electric Supply Company (KESC) faced a shortfall of 500MW because two units of its flagship generating power plant — Bin Qasim — could not generate power while the other four continued to operate much below par.
According to sources, Unit 4 of the plant was out while unit 5 was expected back in a day or two. The sources said that besides a lack of maintenance, the new KESC management’s policy of saving on fuel cost was the real cause of their closure.
Amid much uproar over public inconvenience caused by prolonged outages and inflated bills, the KESC has been pursuing its policy. The huge 40 per cent line losses further compound the problem but hardly any tangible investment has been made to upgrade the utility’s grid and transmission network which comprises 53 grid stations and around 1,153.84-km-long 220KV, 132KV and 66KV overhead and underground cables.
The rate of tripping of the EHT transmission lines and power transformers is exceptionally high. Most of the trippings are indiscriminate in nature, understandably either due to faulty protective gear or improper relay settings. The quantum of tripping can, however, be minimized substantially by replacing the outdated and sluggish protective relays with latest versions.
Settings of most of the protective relays, installed to protect EHT transmission line and power transformers, are improper resulting in delayed or indiscriminate and cascaded tripping in the system. No set36lip exists to support the field formations regarding protection settings, fault analysis etc. Although the technical committee sent by the previous government had made certain recommendations when the operation and maintenance had been with the Siemens, the Al Jomaih management has so far done nothing to improve the system.
Heat rates high
In view of frequent shutdown of Bin Qasim units, it is evident that heat rates and unitwise capacities have deteriorated considerably. According to a report submitted by a technical committee, it was noted that during 20063607, the gross heat rate (BTU/kWh) of Unit364 of Bin Qasim went as high as 12,072 against the designed heat rate of 9,058. Gross heat rate of Unit 4 of the KTPS was as much as 14,257 against the designed heat rate of 9,400. Similarly, heat rate of Unit 2 of the Site GTPS was observed at 16,805 against the designed heat rate of 14,465. Such a situation reflects that performance of the power plants is not satisfactory.
The report reveals that the ratio of forced shutdowns is too high compared to those of planned shut downs. The major overhauling at Unit 1, 2, 3, 4 5 of the Bin Qasim plant was carried out 1516 years after the date of its commercial operation. Similarly, the major overhauling of turbo generator and boiler modification work of oil firing at Unit 3 of the KTPS was carried out 13 years after its commissioning. The comprehensive action plans for 20073608 was also not executed.
Reason for low power generation
The overall installed capacity of the power station is 1,260MW. It comprises six units. The Unit 1 and 2 were commissioned for commercial operation in 19833684, Unit 3 in 1990, Unit 4 and 5 in 1991 and Unit 6 in 1998. At present, all the six units are in operation and delivering around 1,100MW. The reduced generation is mainly due to poor vacuum in condensers of almost all these units. The condenser tubes are often fouled because of silt and scaling. The unit control system of Units 15 is obsolete. Re36heater tubes leakage, HP/LP by36pass system is defective and the high pressure feed water heaters generally remain out of order. Booster pumps of Unit 3 boiler have developed high vibration.
The privatised KESC management had announced that it intended to install a new power generation facility (560MW) within the premises of existing Bin Qasim Thermal Power Station. The date for receiving the bid was July 16, 2007. The contract award was expected by Sept/Oct, 2007 and the project was to be completed by the end of 2009.
However, the KESC management has not made any progress on its plans and, as such, an increase in power generation remains a dream.
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