Variable nozzle height in AOD converter, stage 2

The argon oxygen decarburisation (AOD) process has been the dominant process in stainless steel manufacturing since the late 1960s. The process is based on a mixture of inert gas and oxygen being injected from the side of the converter body in a number of stages. The first stage has the highest proportion of oxygen and with each subsequent stage this proportion is reduced and the proportion of inert gas increases. The purpose of the steps is to maintain a low partial pressure of carbon monoxide in the bubbles so as not to oxidize chromium. An alternative to the AOD process is the vacuum oxygen decarburisation (VODC) process which is an AOD with vacuum during the later stages. The purpose of the vacuum is to further lower the partial pressure of carbon monoxide. VODC is a relatively expensive investment and it is unclear what the ongoing maintenance costs will be. The process also makes it difficult to add scrap to the converter, which can be a problem. This project examines the practical possibilities of moving the nozzles in the converter and what effect this has on the converter process during an entire campaign. Furthermore, numerical models and experiments on a pilot scale answer whether higher-placed nozzles lead to a more efficient AOD process. Finally, the possibility of lowering the bath height above the nozzles by angling the converter is investigated, as well as the effect it has on the process.

VariAOD2 has a total budget of SEK 15.4 million, of which SEK 6 million comes from Vinnova.

Funding agency

Vinnova

Start and end dates

2019-2021