Development of a Negligible Zero-Drift NDIR Analyzer for Measuring NH₃ Emitted from an Urban Household Solid Waste Incinerator

• Main Authors: Trieu-Vuong Dinh, In-Young Choi, Byeong-Gyu Park, Jee-Hyun Lee, In-Young Kim, Han-Nui Gil, Sang-Woo Lee, Jo-Chun Kim
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Atmosphere
• Subjects: NH₃; NDIR; zero-drift; incinerator; CEMS
• Online Access: https://www.mdpi.com/2073-4433/12/7/858

An analyzer for measuring NH₃ emitted from a combustion process has been developed based on a simple non-dispersive infrared (NDIR) technique because of its cost-effective benefit. The weakness of the NDIR analyzer due to interference and zero-drift has been overcome. A least-interfering bandpass filter (BPF) was found and manufactured to compensate for the interfering effects of gases emitted from a combustion process (e.g., CO, NO<i>_x</i>, SO₂, CO₂, H₂O, HCl, formaldehyde, acetaldehyde and toluene). It was found that there was no significant interference in the least-interfering BPF with respect to gases of concern. Measurement errors by the analyzer were less than 2.5% in a range of 1 to 10 ppmv of NH₃ compared to a standard method when the compound was measured in complicated mixing gases. For the zero-drift, using BPFs with identical center wavelength with respect to different incident infrared intensity was found to help minimize the zero-drift of the NDIR analyzer. As a result, the analyzer could cut approximately 19% of zero-drift caused by the aging effect of both IR source and detector. It suggests that the analyzer could be applied for measuring NH₃ emitted from combustion processes with good accuracy and reproducibility.