Utilisation of Thar coal

THE government has decided to convert all existing thermal power plants on coal-firing to save foreign exchange required to import heavy fuel oil (furnace oil). At present the plants are either operating on gas or heavy fuel oil. In future Thar coal is intended to be used in boilers of aH thermal plants.

In this context I would like to mention that due to my 35 years of experience in construction, operation and maintenance of thermal power plants inside and outside of the country, I have some reservations for burning of Thar coal in the existing thermal power plants which are as under: First, Thar coal is lying underground in water. As soon as the coal is taken out, water evaporates and coal becomespowder. It will not be easy to transport the powdered coal to different thermal power plants. All other transportation methods will be very difficult and expensive.

Second, Thar coal is lignite, containing about seven per cent sulphur in it. It will not be suitable for burning in conventional boilers.

Third, a lot of wastage and pilferage is likely to occur on the way from the mine to power plant sites.

Fourth, at the power plants the stacking of coal is necessary to keep plants running round the clock. The stacking of coal is a big problem because the innerlayer ofcoalgets heated up, produces gas which catches fire in the presence of air.

To avoid such fire, we have to compress the stack to remove airand sprinkle water continuously on it to keep it cool.

I have seen in Germany sprinkling of water on the coal stack continuously, though the ambient temperature in Germany remains much low as compared with Pakistan. This coal stack was small and was not meant for burning in the power plant.

In our country big stacks of coal are required, particularly for Jamshoro, Guddu and Muzaffargarh power plants, and it will be difficult to maintain such stacks due to high ambient temperature. Ambient temperature also accelerates coal stack firing.

Generally, thermal power plants are preferred to be installed near coalmines to avoid transportation and stacking of the coal. I visitedtwo thermal power plants in Germany one 1600 MW and another 600 MW installed close to coal mines and the excavated coal was being carried on conveyor belts to boilers directly without stacking.

I suggest that new thermal plants should be installed in Thar area near to the coalmine and the existing thermal power plants in the country be supplied with gas whenever available.

The dual firing equipment (oil and gas) is already existing in almost all thermal units. This will save substantial amount of money required for conversion to coalfiring mode.

MEHR M. SIDDIQUE Ex-General Manager (Thermal) Wapda Lahore