The impact of coal characteristics on the fouling of stoker-fired boiler convection surfaces

Influence of Combustion Parameters on Fouling Composition after Wood Pellet Burning in a Lab-Scale Low-Power Boiler

“…Several theoretical indices that predict fouling and slagging behavior of a solid fuel were calculated. In the base-to-acid ratio (B/A) (Equation (1) of Table 3) [13,21,[25][26][27]31,32], the compounds of group B (the oxides in the numerator) are basic and possess low melting points, whereas the compounds of group A (the oxides in the denominator) are acidic and possess higher melting points [26,33]. This base-to-acid ratio can be used in a simplified form as (B/A(simp)) (Equation (2) of Table 3) [13,25,33].…”

“…In the base-to-acid ratio (B/A) (Equation (1) of Table 3) [13,21,[25][26][27]31,32], the compounds of group B (the oxides in the numerator) are basic and possess low melting points, whereas the compounds of group A (the oxides in the denominator) are acidic and possess higher melting points [26,33]. This base-to-acid ratio can be used in a simplified form as (B/A(simp)) (Equation (2) of Table 3) [13,25,33]. However, this deposition rate has been created for fuels with low phosphorus content, such as coal, which is not the case of biomass.…”

“…These ratios indicate the potential tendencies for slagging and fouling. Otherwise, there are other ratios specifically for slagging, such as slagging index (RS), (Equation (4) of Table 3) [13,26,33] and, slag ratio (SR), indicative of the slag viscosity (Equation (5) of Table 3) [21,25,26]. For fouling, ratios such as fouling index (FU) (Equation ( 6) of Table 3) [13,26,33,34] are employed.…”

“…These indices are based on the inorganic composition of the ash. However, most of the indices were first created for coal combustion [25]. Some of them have been used directly for biomass fuels or were slightly modified because literature on direct biomass indices is scarce [26,27].…”

CFD modelling of particle size effect on stoker coal­fired boilers combustion

“…Study of fine coal accumulation in a CBFB by experimental approach denotes that a proper addition of fine coal particles (in size of 0.45-0.9 mm) in the medium can reduce the bed density effectively [9]. Effect of two types of coal with different characteristics was compared on the degree of fouling in a hot water stoker-fired boiler after it has been fired for an extended period of time [10]. In the previous study of CFD analysis for stoker fired boiler more realistic baseline coal combustion was developed with the heat exchanger models [11].…”