Decoking Performance of Alumina Forming Alloys
Mentor 1
Benjamin Church
Mentor 2
Lizeth Ortiz
Start Date
16-4-2021 2:00 PM
Description
Newer alloys such as alumina-forming stainless steels (AFA) appear to have superior coke deposition (coking) resistance compared to typical chromia-forming stainless steels in the ethylene-making process. In this process, coking resistance is understood while removal of the coke, or decoking, has not been fully researched. Typical decoking procedures utilize air, steam, or both, but there is no evidence behind these environments’ effect on AFAs. AFA and CFA samples were placed through a series of experiments: pre-oxidation, coking, and decoking processes that looked to mimic the environments that the stainless steels would experience in actual use. XRD, SEM, EDS, hardness, and gravimetric measurements of both materials were taken at each of the processing stages mentioned before. It was found that the AFA material saw better decoking properties because of the lack of detrimental carbides like M23C6 and smaller carburized zone when compared to the CFA. Further, results showed that the most oxygen-rich environment removed coke in AFA alloys better compared to other environments and added the least amount of mass in the CFA environment compared to others.
Decoking Performance of Alumina Forming Alloys
Newer alloys such as alumina-forming stainless steels (AFA) appear to have superior coke deposition (coking) resistance compared to typical chromia-forming stainless steels in the ethylene-making process. In this process, coking resistance is understood while removal of the coke, or decoking, has not been fully researched. Typical decoking procedures utilize air, steam, or both, but there is no evidence behind these environments’ effect on AFAs. AFA and CFA samples were placed through a series of experiments: pre-oxidation, coking, and decoking processes that looked to mimic the environments that the stainless steels would experience in actual use. XRD, SEM, EDS, hardness, and gravimetric measurements of both materials were taken at each of the processing stages mentioned before. It was found that the AFA material saw better decoking properties because of the lack of detrimental carbides like M23C6 and smaller carburized zone when compared to the CFA. Further, results showed that the most oxygen-rich environment removed coke in AFA alloys better compared to other environments and added the least amount of mass in the CFA environment compared to others.
