Quantitative Evaluation and Coupling Analysis of Purging Performance in Regenerative Thermal Oxidizers Based on CFD Simulation
Ammonium salt crystallization-induced blockage of the regenerative heat exchanger in regenerative thermal oxidizers (RTOs) remains a critical operational challenge, particularly in pharmaceutical applications where NH4Cl constitutes up to 70% of the fouling deposits. This study employs computational fluid dynamics (CFD) to systematically simulate six purging configurations, varying injection angle and pipe arrangement, and quantifies purging effectiveness via a novel evaluation method based on characteristic observation planes. Using the Realizable k-ε turbulence model coupled with a porous media model, we analyze the velocity distribution and low-velocity failure zones at the gas chamber–regenerator interface. Results demonstrate that a single-pipe 45° oblique injection achieves the highest effective purging area of 57.6%, a 35.7% improvement over conventional horizontal purging. Increasing pipe diameter significantly enhances flow uniformity, yielding an efficiency gain of approximately 40%, outperforming mere increases in gas velocity. A synergistic optimization strategy is proposed, prioritizing high-performance purging structures with coordinated parameter tuning. The recommended configuration—single-pipe 45° injection, 280 mm pipe diameter, and 14 m·s−1 gas velocity—achieves 88.2% purging efficiency without additional fan power, representing a 45.6% improvement over conventional modes. These findings provide a theoretical basis and engineering solution for RTO purging system design and operational optimization.