Achieving Ultra-Low NOx Emissions: A Case Study

Nitrogen Oxide Treatment Project for Hefei Thin Film Material Co., Ltd.

This project began operating in May 2021. It treats high-concentration nitrogen oxide waste gas produced when nitric acid dissolves indium. Data from the client show that the indium dissolution reactor emits nitrogen oxides at concentrations as high as 180,000 mg/m³. The project site lies less than 1,000 meters from nearby residential buildings. Regulations require nitrogen oxide emissions to remain below 100 mg/m³. The treated gas must also be colorless and odorless.

To meet these specific conditions, we designed a treatment system that includes two-stage bubble oxidation, three-stage water jet treatment, and four-stage jet absorption. The process allows the client to recover and reuse the absorbed acid solution. During material trial runs, tests showed that nitrogen oxide emissions measured 80 mg/m³. The system now operates steadily.