A new wrought alloy has been developed for use as furnace tubes in ethylene pyrolysis plants. This alloy has an excellent carburization resistance due to uniform formation of protective Al2O3 oxide scale on the metal surface. At temperatures between 1000°C and 1150°C, laboratory corrosion tests have been carried out to evaluate carburization resistance of the developed alloy. Commercial austenitic stainless steels used for furnace tubes were tested for comparison. In a simulated carburizing environment of 15vol%CH4-3%CO2-82%H2 gas mixture, the developed alloy has a three times better carburization resistance than the conventional austenitic stainless steels containing more than 25mass% chromium and high silicon at evaluated temperatures.

Another laboratory test has been conducted to clarify carburization and coking resistance under conditions of cyclic carburization and oxidation environments. Carbon ingress and coke deposition of conventional alloys forming chromium oxide scale increased with increasing heat cycles, whereas the developed alloy remained unchanged. Based on these results, carburization and coking behavior of alloys used as ethylene pyrolysis furnace tubes has been explained.

Subject
Carburization, Pyrolysis, Metal surfaces, Nickel based alloys, Oxide formation, Tubes, Commercial alloys, Furnaces, Oxide scales, Ethylene, Carbon, Aluminum alloys, Alloys
Keywords:
ethylene pyrolysis, hydrocarbon, high temperature, carburization, coke, coking, aluminum, alumina, oxide, carbide
© 2002 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2002
Association for Materials Protection and Performance (AMPP)
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