Blending of imported coal: Mandatory 30% norm to be incorporated in tender documents

Shortage of domestic coal supplies in the country has forced the Ministry of Power (MoP) to consider measures that would allow an increase in the blending ratio for imported coal in power stations.

• At present, use of imported coal is limited to about 10% of the coal used to fuel Indian boilers, due to its relatively higher slagging and fouling potential. Also, certain components in the imported coal tend to corrode boiler parts and emit more smoke when used with Indian designs.
• However, boilers provided with Gas Recirculation (GR) fans and systems are more tolerant of imported coal, and may be amenable to an increase in blending ratio.
• The ministry is already in talks with Bharat Heavy Electricals Limited (BHEL), which is expected to incorporate suitable modifications to its power plant designs to allow the greater use of imported coal. Such changes include mandatory incorporation of GR systems, as well as relevant changes to the ducting, ESP sizes etc.
• The Ministry of Power has proposed to incorporate a clause in all power plant tender documents to be issued in the future, necessitating a minimum 30% blending ratio for imported coal with respect to feedstock. Such a stipulation would be first seen in the the upcoming bulk ordering tender for 800 MW supercritical boiler units.  
• While the Gross Calorific Value (GCV) of 30% blended coal is similar to that of Indian coal of the best possible quality, other parameters, like sulphur, IDT, Calcium and Iron in ash etc., are extremely different. 
• In view of the above, the power equipment suppliers will be required to incorporate suitable modifications to their boilers, so as to operate efficiently even with such a wide range of parameters. Pertinently, this would call for installation of Gas Recirculation fans, as well as larger electrostatic precipitators and ducting.