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Tito Luiz da Silveira and Iain Le May

REFORMER FURNACES: MATERIALS, DAMAGE MECHANISMS, AND ASSESSMENT
Tito Luiz da Silveira
Tito Silveira Engenharia e Consultaria Ltda Rua Couto de Magalhães, 744 20930-090 Rio de Janeiro, RJ Brazil

and Iain Le May *
Metallurgical Consulting Services Ltd. Saskatoon, Canada

:‫اﻟﺨﻼﺻـﺔ‬
‫ُﻌﺘﺒﺮ ﺗﻘﻴﻴﻢ اﻟﺘﻠﻒ ﻓﻲ اﻓﺮان اﻟﺘـﱠﺤﻮل ﻣﻦ اﻷﻣﻮر اﻟﻬﺎﻣﺔ ﻓﻲ ﺗﺤﺪﻳﺪ ﻋُﻤﺮاﻟﺨﺪﻣﺔ ﻟﻬﺬﻩ اﻷﻓﺮان. وﺳﻮف ﻧﻌﺮض‬ ‫ـ‬ ‫ـ‬ ‫ﻳ‬ ‫ﻓﻲ هﺬا اﻟﺒﺤﺚ ﻃﺮق ﺗﻘﻴﻴﻢ هﺬا اﻟﺘﻠﻒ، وﻧﻘﺪم اﻟﻤﻨﺤﻨﻴﺎت اﻟﻤﻤ ﱢﺰﻩ ﻟﺘﻘﻴﻴﻢ اﻟﺘﻠﻒ، وه ﺬﻩ ﺗـ ُﻌﺘﺒﺮ ﻃﺮﻳﻘ ﺔ ﺳ ﻬﻠﺔ وﻣﻌﻘﻮﻟ ﺔ‬ ‫ـ‬ ‫ﻴ‬ ‫ﻟﺘﻘﻴﻴﻢ ﻣﺪى اﻟﺘﻠﻒ اﻟﻨﺎﺗﺞ ﻓﻲ أﻓﺮان اﻟﺘﺤﻮل ذات اﻷﻧﺒﻮب. وﺳﻮف ﻧﻌﺮض أﻳﻀﺎ ﻣﺜﺎﻻ ﻟﺤﺎﻟﺔ درﺳ ﻨﺎهﺎ ﻟﺘﺤﺪﻳ ﺪ اﻟﻌﻤ ﺮ‬ ً ً .‫اﻟﻤﺘﺒﻘﻲ ﻻﺳﺘﺨﺪام هﺬا اﻟﻔﺮن ﻋﻦ ﻃﺮﻳﻖ دراﺳﺔ ﺗﺸﻘﻘﺎت اﻟﺠﺪران وذﻟﻚ ﺑﺎﺳﺘﺨﺪام ﻣﻴﻜﺎﻧﻴﻜﻴﺔ اﻟﺘﺸﻘﻖ ﻏﻴﺮ اﻟﺨﻄﻴﺔ‬

* Address for correspondence:P.O. Box 5006, Saskatoon, SK, Canada S7K 4E3 Tel: (1-306) 934-9191 e-mail: lemayi@metallurgicalconsulting.net

Paper Received 17 April, 2006

December 2006

The Arabian Journal for Science and Engineering, Volume 31, Number 2C

99

Tito Luiz da Silveira and Iain Le May

ABSTRACT The assessment of damage in reformer furnaces is an important factor in determining their remaining safelife. In this paper the methodology of damage assessment is reviewed, and the concept of characteristic curves to assess damage is introduced: this provides a simplified procedure to give a realistic estimate of the extent of damage and the remaining life of reformer furnace tubes. An example is also given of a case study to determine remaining life in the presence of a partthrough-wall crack in acomponent in the header of a reformer furnace using a nonlinear fracture mechanics approach. Key words: reformer furnaces; high temperature materials; damage mechanisms; damage assessment; inspection; remaining life prediction

100

The Arabian Journal for Science and Engineering, Volume 31, Number 2C

December 2006

Tito Luiz da Silveira and Iain Le May

REFORMER FURNACES: MATERIALS,DAMAGE MECHANISMS, AND ASSESSMENT
INTRODUCTION Reformer furnaces are used widely in the petrochemical industry to produce hydrogen from hydrocarbons. The hydrogen production takes place in radiant tubes containing a catalyst, as a result of endothermic reactions between hydrocarbons (mostly methane) and water vapor. The design of reformer furnaces has improved greatly over the past 30 years. Newalloys and manufacturing processes have been developed to meet the severe requirements imposed on the tubes in the radiation zone and in the hot reaction gas outlet. There has been improvement in catalysts to provide lower reaction temperatures. However, at the same time, there has been a trend towards increased temperature and pressure to achieve further increases in production and efficiency.Figure 1 shows the arrangement of a typical small or medium sized furnace with the reformer columns, which contain the catalyst, arranged in the form of two vertical walls. The number of columns varies between 15 and 200, depending on the number and size of the walls. Most modern furnaces are of the top-fired type with burners disposed in rows on both sides of the columns, while older furnaces may beof the side-fired type with burners distributed in two or more layers. The columns receive the charge through the inlet pigtails of Cr–Mo low alloy steel above the roof of the radiation chamber. The pigtails have a shape that provides flexibility to accommodate the axial displacement of the horizontal inlet manifold and of the vertical columns produced by thermal expansion.

Figure 1. Schematicview of a top fired reformer furnace

December 2006

The Arabian Journal for Science and Engineering, Volume 31, Number 2C

101

Tito Luiz da Silveira and Iain Le May

The columns are suspended through the use of counterweights or hangers. Depending on the design, a fraction of the weight of the columns is transmitted to the furnace structure at their lower ends. The reaction gas...
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