Optimizing Ash Deposit Removal System to Maximize Biomass Recycling as Renewable Energy for Co2 Reduction

The black liquor is valuable biomass that can be recycled as renewable energy in the form of CO2 -neutral fuels. However, the combustion of biomass results in a large amount of ash deposits reducing heat transfer efficiency. Therefore, all recovery boilers have an ash deposit removal system (ADRS). However, its operation is inefficient; biomass recycling is decreased and CO2 emissions increased as significant amounts of steam and heat energy are wasted. To solve these problems, this study addressed optimizing ADRS to maximize biomass recycling as renewable energy for CO2 reduction. This study mainly consists of two parts. First, to predict power generation, a process model of the recovery boiler with an ADRS was developed, and the model was used to define mathematical equations. Second, a mathematical model was proposed to maximize biomass recycling. The increase in biomass recycling is calculated by multiplying net power generation by the amount of saved biomass per increase power generation. As a result, 16.135 ton/d of black liquor was saved with respect to improving the recycling efficiency, and the CO2 emissions were decreased by 541–996 ton/y following an increase in the power generation by 2,987 MWh/y and in the net present value by $ 16,797,303