Influence of Oxygen on the Thermal Decomposition Properties of C₄F₇N–N₂–O₂ as an Eco-Friendly Gas Insulating Medium

Abstract

The C4F7N (fluorinated nitrile) gas mixture has been recognized as the most potential substitute gas to SF6 used in gas-insulated equipment. In this paper, we explored the thermal stability and decomposition properties of the C4F7N–N2–O2 gas mixture. The influence mechanism of oxygen content and temperature on the byproduct generation was obtained and analyzed. It was found that thermal decomposition of the C4F7N–N2–O2 gas mixture mainly produces CO, C3F6, C3F8, CF3CN, (CN)2, and COF2. The addition of oxygen could accelerate the decomposition of C4F7N. The content of C3F6 and (CN)2 decreases, while the yield of CF4, CO, C3F8, and COF2 increases with the oxygen content. Thermal decomposition of the C4F7N–N2–O2 gas mixture at temperatures lower than 425 °C results from the interaction between C4F7N and the metal heating element, while the bond cleavage reactions occur at higher temperature. As for engineering application, the oxygen added in the 6%C4F7N–94%N2 gas mixture should not exceed 6% to avoid the negative effect of oxygen on the thermal stability of C4F7N.

Review on decomposition characteristics of eco-friendly gas insulating medium for high voltage gas insulated equipment

“…The influence of O 2 on the thermal decomposition characteristics of C 4 F 7 N-CO 2 and C 4 F 7 N-N 2 gas mixtures was also investigated; the main products included CO, C 3 F 6 , C 3 F 8 , CF 3 CN, C 2 N 2 and COF 2 . The addition of oxygen promoted the decomposition of C 4 F 7 N and the yields of CF 4 , CO, C 3 F 8 and COF 2 increased with oxygen content [117,118]. At present, experimental studies on the thermal decomposition characteristics of C 4 F 7 N have confirmed its excellent thermal stability.…”

Adsorption of a MoSe2-Based Sensor for Fluorocarbon Gas Decomposition Products in Gas-Insulated Switchgear: A First Principles Analysis

“…During the discharge process, fluorocarbon gases decompose to CF 3 and CF 2 radicals, and these radicals react with trace water and oxygen to generate characteristic products. − In this work, the adsorption simulation of such characteristic gas components will be carried out to analyze the gas sensing characteristics of the MoSe 2 monolayer to fluorocarbon gas decomposition components. The adsorption parameters and electronic behavior of COF 2 , CF 4 , and C 2 F 6 on Pt–MoSe 2 monolayer are calculated.…”

Eco-friendly gas insulating medium for next-generation SF6-free equipment

“…Specifically, C 3 F 6 is first detected, followed by C 2 N 2 , CF 4 , C 3 F 8 , etc. The fluorinated ketones demonstrate similar thermal decomposition properties, and the by-products including CF 4 , C 2 F 6 , C 3 F 8 , C 3 F 6 , C 3 F 7 H, C 5 F 12 are generated [168] . Besides, the gas pressure plays an important role in thermal decomposition.…”