Optimizing ash deposit removal system to maximize biomass recycling as renewable energy for CO2 reduction
Jonghun Lim, Junghwan Kim
Abstract
The black liquor is valuable biomass that can be recycled in the form of CO2-neutral fuels and is burned in recovery boiler furnaces to produce steam for power generation. However, the combustion of biomass results in a large amount of ash deposits, which reduce the heat transfer efficiency. Therefore, all recovery boilers have an ash deposit removal system (ADRS). However, its operation is inefficient, significant amounts of steam energy are wasted, and CO2 emissions are increased. 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 and the amount of saved biomass. As a result, 16.135 ton/d of black liquor was saved, 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.