[email protected] | +61 (0)425318397
[email protected] | +61 (0)425318397
AOE is the exclusive distributor of Griffin Coal in Perth. Griffin Coal offers great coal quality and is priced below average market rates. They operate in an open cut coal mine in Colie, Western Australia since 1927. They have the largest coal resource in Western Australia (~850 million tonne) with a current mining circa of 2.6 million tonnes per annum.
HGI of 55-75 for GRIFFIN coal indicates softer coal as compared to other similar CV coal’s HGI of mostly 42-47. With higher HGI, the mill capacity increases. Usage of Griffin Coal results in around 20% better through-put relative to other origin similar CV coal for the same power consumption
HGI of 55-75 of Griffin coal makes it more blending-friendly coal for coals that have HGI varying between 48 and 65. For example, in India, coal blending is resorted to poor GCV coal firing to increase the heating values, to obtain stable flame conditions during monsoon period, and to supplement coal supplies shortage.
Total Moisture in GRIFFIN coal is less than 24% typical (most of other origin similar CV coal have moisture between 25% and 48%. Moisture significantly affects coal-handling behaviour. There are significant advantages in using Griffin Coal owing to its relatively lower moisture content.
i. Relatively lower moisture content results in better and smoother coal handling operations.
ii. Relatively lower moisture content in Griffin coal also results in:
a. Less chute plugging problems,
b. Better mill out-let temperatures, and
c. Lower power consumption in CHP, mills and fans.
iii. Optimal freight charges: Freight charges for coal transportation depend on the quantity of coal shipped. This implies freight cost per 1000 kCal is cheaper for Griffin coal because of its relatively lower moisture content.
iv. Smaller APH sizing: For new plants; APH sizing· would be small for coal with relatively lower moisture content. In existing plants, energy requirement is lesser for drying the lower moisture coal in mills using hot primary air.
Empirical evidence from burning Griffin Coal at an Indian power station indicates that Boiler efficiency from using Griffin coal is 86.54% (against 84.48% for other origin similar CV coal) due to higher Fixed Carbon and relatively lower moisture content compared to most of other origin similar CV coal. 2% increase in boiler efficiency results in improvement of almost 50 kcal/kWh in station heat rate.
Sulphur in Griffin coal is less than 0.65% typical (for most of other origin similar CV coals, it may go up to 0.9% and higher). In a typical 600 MW subcritical unit, relatively lower Sulphur content of Griffin. Coal results in around 30% less SOx emissions. For new units, the FGD capacity can be 30% lower. For existing units, power savings of around 30% is possible. Lower Sulphur content implies low 502/503 generation. It implies lower susceptibility of air preheater cold end corrosion with Griffin coal compared to most of other origin similar CV coal.
Griffin coal’s typical ash fusion temperature (IDT in reducing atmosphere) is > 1,350 °C typical and Base to Acid ratio is 0.1 typically. This makes Griffin coal averse to slagging and fouling. Other origin coals of similar CV have generally 1120-1200 °C AFr (IDT in reducing atmosphere) and Base to Acid ratio of 0.68 to 0. 70, which makes such coals more prone to slagging and fouling. That may require additional wall blowers, adding to the capital cost. That may also require more frequent soot blowing, resulting in higher auxiliary steam consumption, and hence more fuel consumption.
Fouling index or Slagging Factor of Griffin Coal is 0.04 (against other origin similar CV coal’s 0.81 mostly). Griffin coal has no fouling propensity. Most of other origin similar CV coals have higher fouling propensity. That may call for additional retractable blowers in convective pass, adding to the capital cost. That may also require more frequent retractable soot blowing resulting in higher auxiliary steam consumption, and hence more fuel consumption.
The Oxides of calcium, Magnesium, sodium and potassium in Griffin Coal are very less as compared to most of other origin similar CV coal, where these constitute to 15-20%. Due to this property of Griffin Coal, ash dyke, water pH will be near neutral, whereas in case of other origin similar CV coal’s usage, it goes up to 12. Thus, pH correction system is not required in ash water recovery unit for using Griffin coal and hence, Griffin Coal is more environment-friendly relative to most of other origin similar CV coal.
Resistivity of fly ash decreases with increase in Sulphur, Fe203, K20 and Na20, and increases with increase in Cao, Si02, Al203. The resistivity of fly ash is positively correlated to higher collection efficiency in the ESP. Fly ash resistivity between 104 and 108 Q-cm results in low collection efficiency in the ESP, between 108 and 1010 Q-cm results in moderate collection efficiency in the ESP, and between 1010 and 1011 Q-cm results in high collection efficiency in the ESP. Griffin Coal’s fly ash resistivity is between 109 and 1011 . It results in higher collection efficiency in the ESP, whereas for most of other origin similar CV coals, fly ash resistivity is between 108 and that results in moderate collection efficiency in the ESP.
Volatile matter in GRIFFIN coal is 22.5% -24% (ARB) as against most of other origin similar CV coal’s VM of 35% to 42% (ARB). High VM coal requires careful handling, particularly in summer, as it is prone to catching fire. Lower mill outlet temperature of 50-55 °C needs to be maintained for other origin similar CV coals as compared to 75-90 °C temperature for Griffin coal. High VM coal also requires more stringen.t and more elaborate stock yard management to minimize coal pile fires.
For high VM coal, additional. CO monitoring may be required in coal silos,· bunkers and tripper floors. Griffin coal is well placed in this· regard relative to other origin similar CV coal with higher volatile matter.
Sodium in coal vaporizes in boiler and condenses in low temperature area of ash handling system. Higher sodium oxide levels in other origin sim.ilar CV coals leads to formation of lumps in dry ash conveying system, causing frequent down time in ash handling system. This problem does not occur with usa·ge of Griffin coal as sodium oxide level is very low.
Deposits formation only due to adhesiveness of ash particles does not lead to occurrence of bonded deposits on heating surfaces. The bonding is accelerated by chemically active components, like Cao, that_ promote the formation of monolithic substance in the deposits. The Cao in Griffin coal ash is only 0.37% to 0.40% typical. Higher Cao in most of other origin similar CV coal accelerates deposition on heat exchangers, mainly where the flue gas velocities are relatively low, in Air Preheater, for instance. The plugging of air preheater results in an increase of differential pressure across the APH. This leads to higher power consumption in Id, FD and PA fans. This also calls for more frequent APH soot blowing, which in turn increases the fuel consumption. Thus, Griffin coal is more advantageous to use relative to other origin similar CV coal.
