Simultaneous mitigation of biomass ash-related issues using mineral additives: mechanism, optimization and economic viability

Abstract

This study utilized mineral-based additives namely kaolin, coal fly ash (CFA), and CaCO₃, which can potentially mitigate biomass (agro-residue) ash-related issues in boilers and furnaces. It examined the effects of these additives mixed with biomass at a 950 °C combustion temperature with concentrations ranging from 2 to 10 wt% on the simultaneous retention of volatile potassium (K), sulfur (S), and other ions. At the same time, it assessed their impact on fuel properties and fusion behavior during biomass combustion. Kaolin and CFA significantly enhanced K retention (20–68%), while CaCO₃ achieved the highest S retention (42–98%). CFA had the highest impact on calorific value (CV), reducing it by 10.59% at 10 wt% concentration. Whereas kaolin had the highest impact on ash content (AC), nearly doubling at 10 wt% compared to when no additives were used. CaCO₃ at 6 wt% achieved most optimal results, retaining maximum K (30.87%) and S (91.51%) with minimal changes in AC (13.10%) and CV (3.35%) for ash fusion temperature (fluid temperatures) > 1350 °C. The study also revealed the retention effect of additives on other ions, including Mg (~ 65%) and Ca (fourfold increase), with minimal effects on PO₄³⁻ (< 10%) and Na (< 15%). Preliminary economic feasibility analysis showed negligible cost differences when using additives. Total production cost for electricity generation is at 7.41 ₹/kWh for 6 wt% CaCO₃ which is only approximately 1.2% higher than using mixed biomass without additives. This is a novel approach of simultaneous optimization of five critical parameters while evaluating the preliminary economic feasibility of possible implementation of these additives in industrial-scale power generation using biomass.

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