Design and optimization of the continuous emission monitoring system based on ejector

• The ejector is introduced into the CEMS sampling system for the first time. • A miniaturized ejector is designed for small-flow flue gas detection. • The designed ejector has strong robustness and broad operational adaptability. In response to global warming, emissions monitoring has become increasingly important for meeting emissions limits and maintaining an accurate emissions data inventory. The continuous emission monitoring system is a key technology for real-time monitoring of industrial waste gases. However, the current continuous emission monitoring system has some disadvantages in its sampling process, such as unstable data acquisition, pipeline leakage, and high maintenance costs for sampling equipment. Additionally, using bump sampling may introduce the risk of lubricating oil pollution. This study aims to provide an efficient and stable sampling device based on ejectors, avoiding introducing other pollutants while reducing the maintenance costs of the equipment. This research uses a computational fluid dynamics simulation to examine how the ejector geometry parameters affect the flow characteristics of the entrained fluid, and the ejector is designed and optimized accordingly. The outcomes demonstrate that the mass flow rate of the optimized ejector can be stabilized at 1.46E-5kg/s, with strong robustness within the range of ±7.1% of primary flow conditions. This research demonstrates that the ejector can be applied to the sampling system in the continuous emission monitoring system, providing a valuable reference for the design of small mass flow ejectors.