The determination of nitrogen-to-carbon ratio in urea synthesis using gamma radiation technique and comparison with oscillation technique

• This study introduces a non-invasive gamma radiation technique for real-time monitoring of the nitrogen-to-carbon (N/C) ratio in urea synthesis, offering significant advantages over traditional methods. • The gamma radiation method achieved measurements with an accuracy of better than 0.5 % at 2σ, demonstrating strong agreement with the conventional oscillation technique (R² = 0.9918). • The gamma radiation technique eliminates the need for physical probes, reduces maintenance, and avoids sampling-related issues, making it ideal for harsh industrial environments. • The method provides continuous, online N/C ratio measurements, enabling dynamic process adjustments to optimize urea production efficiency and product quality. • A 24-hour performance evaluation confirmed the gamma radiation technique's superiority over the oscillation method, particularly in stability and reliability under real-world conditions. Accurate ratio control of the components in the urea synthesis section plays a crucial role in achieving stable and efficient operation of the urea process. Additionally, obtaining the optimum yield of urea in the stripping urea process requires the reactants to be present at a specific ratio, known as the N/C ratio. In this study, the gamma radiation technique was employed to measure the density of urea, which has a linear relationship with the N/C ratio. In this technique, a ¹³⁷Cs source and a NaI(Tl) detector were positioned on opposite sides of the outlet pipe to measure the density of urea under processing conditions. The measurements were conducted with an accuracy of better than 0.5 % at 2σ. The NC meter was capable of measuring a density range between 500 kg/m³ and 2000 kg/m³. The measured results were compared with data acquired using the oscillation technique, showing a strong agreement between the two methods. Consequently, the gamma radiation technique demonstrates superior advantages over the oscillation technique and other methods due to its non-contact, non-invasive, non-destructive, online, cost-effective, and real-time characteristics.