Blending of coal process is practiced for combustion and gasification, particularly in power generation which is distinguished from blending for coke production in the steel industry.
Applying blending techniques go a long way in reducing the cost of power generation. The low-grade coals can be mixed with high grade coal while retaining thermal performance of the boiler.
Generally, any two coals can’t just be blended. Successful blending occurs with respect to non-additive properties (likes combustion reactivity of coal, ash characteristics, grindability index, and swelling characteristics) of two coals.
Coal industries are using different type of blending methods such as blending in bed, blending by silo, blending by ground hopper and blending on moving belt. Among them, the most common is the blending on moving belt which is used for all coal processing industries.
Taking an environment-friendly approach in thermal power plants with coal blending requires an understanding of the interaction of inorganic components of coals in the blend process and how it affects ash behavior including its emissivity, and thermal conductivity. Combustion efficiency and carbon loss of blended coal, other aspects of slagging, fouling and emission characteristics like NOx, SOx and emission of particulate matter are to be studied. Optimisation in process helps in ensuring cost effective and environment-friendly power generation in coal-fired thermal plants.