Estudo experimental a frio de diferentes configurações de aeração de uma válvula loop-seal na fluidodinâmica de uma fornalha piloto de leito fluidizado circulante

Abstract

Solid recirculation valves, known as loop-seals, are crucial components in circulating fluidized bed (CFB) systems. Their main function is to replenish the amount of solids entrained in the main column or riser, ensuring the continuous and proper circulation of particles for the system’s optimal operation. In this study, conducted at the Thermochemical Processes Laboratory of UTFPR/Campus Ponta Grossa, a pilot-scale circulating fluidized bed boiler was tested under cold conditions to experimentally evaluate two aeration configurations of the loop-seal valve. The expected results include identifying efficient operating conditions for the CFB, analyzing solid recovery, and comparing static pressure profiles with the corresponding pressure drops in the riser and downcomer components. A total of 32 experimental tests, designed under a 2⁴ factorial plan with repetition to verify the reproducibility of the experiments, were conducted to assess the influence of the applied aeration configurations in the loop-seal valve under two levels of riser fluidization velocity, total solid inventory, and aeration volumetric flow rate. Excellent system responses were obtained from the tests, with axial pressure profiles corresponding to those reported in the literature, thereby demonstrating the system's functionality. The results indicated that the A-C configuration performed better in terms of stability and exhibited lower pressure variation compared to the A-B configuration. Furthermore, it was observed that the aeration configuration directly influences the system's behavior, being a determining factor for its efficient operation under higher fluidization velocity conditions. In tests with lower velocities, this influence was reduced, suggesting that the applied aeration rate should be aligned with the specific operational conditions of the CFB.