A Numerical Study on 1D Simulation Model for Determining Particle Size Change in a Circulating Fluidized Bed Boiler

Abstract

New and renewable energy usage is expanding, but thermal power plants are still critical as a stable power source. For coal-fired power plants to play a role in responding to climate change until other technological alternatives are prepared, next-generation coal-fired power plants must be equipped with high-efficiency, low-emission (HELE) technology. In the existing HELE technology, low emission meant a reduction of pollutants such as NOx, SOx, and PM (particulate matter), but now greenhouse gases are also a reduction target. The existing thermal power plants can supply massive low-carbon power through fuel diversification with low-carbon fuels. From this perspective, a circulating fluidized bed (CFB) boiler represents an optimal solution, and the importance of numerical analysis techniques is increasing in using various fuels in CFB boilers. The particles in the CFB boiler demonstrate alterations in particle size as a consequence of cracking and abrasion resulting from particle-wall and particle-to-particle collisions. The re-designed particle size distribution (PSD) of intrinsically induced fuel fragmentation within a furnace differs from the initial fuel particle size. If the PSD change effect is obvious, the redefined PSD should be used for a numerical simulation of a CFB boiler. In this study, we investigated the effect of fuel fragmentation on the operation of a CFB boiler through 1D simulation. The fuel fragmentation factor is specified as a variable with a range of values. It has been demonstrated that the average particle size of the fuel introduced to the boiler can vary by more than 40%, depending on the degree of fragmentation of the fuel. Consequently, alterations in the PSD impact the transfer of heat and the temperature of the bed, which in turn affects combustion efficiency. These results show that accurate estimation of the solid size in the boiler is essential for the numerical simulation of a CFB boiler.