Abstract
Although replacing biomass, (e.g., wood chips and pellets), with thinning wood and herbaceous biomass is eco-friendly and economically advantageous, their direct utilization in plant boilers is associated with ash-related challenges, including slagging and fouling. The aim of this study is to determine the effects of ash removal treatment (ashless biomass (ALB)) in the context of solid fuel power plant boilers. Ash was removed via neutralization of metal ions and carboxylic acids contained in the biomass ash. The ash removal rate of K, Na, Cl was indicated by assessing the total biomass before and after ash removal treatment, via XRF analysis. Co-combustion with sub-bituminous coal and ALB-treated biomass was analyzed using a drop tube furnace and revealed that NOx and SOx values converged converge toward an approximate 10 ppm error, whereas the Unburned Carbon (UBC) data did not exhibit a specific trend. Factors associated with slagging and fouling, (capture efficiency (CE), and energy based growth rate (GRE)) were calculated. All biomass samples without pretreatment exhibited V-shaped variation. Conversely, for ashless biomass (ALB) samples, CE and GRE gradually decreased. Thus, the ALB technique may minimize slagging and fouling in a boiler, thus, reducing internal corrosion associated with ash deposition and enhancing the economic operation of boilers.
Highlights
Power generation using biomass, which is a renewable energy source, is attracting significant attention
The current study aims to extend these investigations to assess the challenges associated with increasing the biomass mixing ratio to 10% in PC boilers, as well as the advantages associated with ash removal pretreatment to limit the negative impact of ash deposition
The slagging and fouling associated with underexploited biomass (TW and kenaf) before and after ash removal pretreatment was investigated
Summary
Power generation using biomass, which is a renewable energy source, is attracting significant attention. Ash from underexploited biomass contains significant alkali metals (K and Na) and chlorine (Cl), and converting these to stable fuels is challenging due to the simultaneous equipment (clinker, slagging, fouling, hot corrosion, etc.) and environmental (ultrafine dust source generation) issues. In the current study, the alkali metal and chlorine contents were the primary focus when assessing the effects of three different types of biomass, namely, underexploited biomass, including thinned wood (TW) and kenaf, and the reference biomass, wood pellet (WP). Considering that ash content (alkali, chlorine content) impacts slagging and fouling problems, and is the primary cause of ash deposition [6,7,8], the ALB technique was employed to remove alkali metals and related components from the biomass in this study. 0.00 ad: air dry, DAF: dry ash free, LHV: low heating value
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