Novel Sampling and Sample Preparation Systems with Industrial Validation for Biomass–Coal Co-Combustion Ratios Based on 14C Determination

Focusing on enhancing the performance of the 14C method in determining biomass–coal co-combustion ratios, this study developed two novel sample preparation systems: a direct flue gas injection benzene synthesis system based on Liquid Scintillation Counting (LSC) and a direct flue gas sealing graphitization system based on Accelerator Mass Spectrometry (AMS). These systems reduced sample preparation time from 20–24 h to 6–8 h. Experimental validation showed relative errors in biomass blending ratios (1–40%) below ±4% for LSC and ±3% for AMS, except at the 1% blending condition. Compared with conventional methods, both accuracy and efficiency were significantly improved. An enhanced 14C-based industrial measurement scheme was established and successfully applied for monitoring biomass blending ratios (15–50%) in industrial facilities. Deviations between AMS and LSC were within ±3%, confirming the method’s accuracy, despite discrepancies with the Distributed Control System (DCS) estimates. Additionally, predictive formulas for 14C activity in biomass and air CO2 reduced economic investment, with relative errors from ±0.04% to ±3.25%. Overall, the new scheme improved accuracy by 50%, efficiency by 60%, and reduced detection costs by 60–80%, demonstrating feasibility and practical value for industrial applications.