Fig. 1. H₂S absorption cross section in 200‒240 nm band

Fig. 2. Diagram of the H₂S volume fraction measurement device based on UV absorption spectroscopy

Fig. 3. Absorbance curves for different volume fractions of H₂S

Fig. 4. Linear fitting between different volume fractions and integral values

Fig. 5. Linear fitting of measured volume fraction and standard volume fraction

Fig. 6. Internal and external drawing of H₂S measurement device

Fig. 7. Variation curve of light intensity signal at 215 nm

Fig. 8. Volume fraction and relative error measured by H₂S instrument

Fig. 9. Diagram of on-site biogas transportation and instrument installation

Fig. 10. Diagram of on-site instrument installation and portable instrument

Fig. 11. H₂S volume fraction change in on-site biogas