Inhibition of carbon deposition on iron and steel surfaces

✍ Scribed by W Karcher; P Glaude

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 730 KB
• Volume: 9
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(71)90083-2

✦ Synopsis

Experiments have been carried out on the feasibility of inhibiting the deposition of carbon which takes place by catalytic decomposition of CO on iron and steel surfaces. Two distinct classes of inhibitors have been investigated: firstly, compounds exerting an irreversible effect, such as SO, and various silanes; and secondly, inhibitors (H20, NrO, NH3, and CO,) which are effective only as long as they are continuously added to the reaction mixture. It is shown that-with the exception of C02-all the inhibitors suppress the deposition of carbon on iron and steel surfaces completely if they are present in the reaction mixture in argon in a sufficient concentration. The inhibition effect decreases in the order SO2 > silane > Hz0 1 N,O > NH, > CO*. Measurements of the retarding influence of Hz0 as a function of Hz/H20 ratio indicate that, in High Temperature

Gas-Cooled Reactors where CO and Hz are present in the helium coolant in low and approximately equal concentrations, the deposition of carbon can be prevented on heat exchanger surfaces during normal operation if the Hz/Hz0 ratio is maintained between 15 and 20. High CO partial pressures and Hz/Hz0 ratios may be tolerated temporarily if a silane inhibitor is added in small doses to the helium coolant.