Experimental study on the generation of carbonaceous dust formed by chemical vapor deposition in HTGR

Carbonaceous dust can bring some potential threats to the safe operation of the high temperature gas-cooled reactor. Predictive models based on physical generation mechanism have produced errors in regards of actual observations. Thus, the chemical generation mechanism is worth investigating. This paper mainly analyzes the formation of carbonaceous dust by chemical vapor deposition with carbon monoxide and hydrogen mixture as feed gas. The adopted substrate is made of Inconel 617 alloy. The effect of hydrogen content and reaction temperature on the generation of carbonaceous dust have been investigated. The morphology and microstructure of the deposited carbonaceous dust have been characterized by scanning electron microscope, energy dispersive spectrometer, and Raman spectrum. The experimental results show that the production of the carbonaceous dust is almost in parabolic relationship with H2 flow rate, while for the influence of reaction temperature, the result is much closer to exponential relationship. In addition, two kinds of carbonaceous dust particles, larger agglomerate particles and small isolated particles, have been observed.