Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

PDF Version Also Available for Download.

Description

Advanced electric power generation systems use a coal gasifier to convert coal to a gas rich in fuels such as H{sub 2} and CO. The gas stream contains impurities such as H{sub 2}S and HCl, which attack metal components of the coal gas train, causing plant downtime and increasing the cost of power generation. Corrosion-resistant coatings would improve plant availability and decrease maintenance costs, thus allowing the environmentally superior integrated-gasification-combined-cycle (IGCC) plants to be more competitive with standard power-generation technologies. Heat-exchangers, particle filters, turbines, and other components in the IGCC system must withstand the highly sulfiding conditions of the high-temperature ... continued below

Creation Information

Krishnan, Gopala N.; Malhotra, Ripudaman; Perez, Jordi; Hornbostel, Marc; Lau, Kai-Hung & Sanjurjo, Angel May 31, 2007.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 25 times , with 4 in the last month . More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

Advanced electric power generation systems use a coal gasifier to convert coal to a gas rich in fuels such as H{sub 2} and CO. The gas stream contains impurities such as H{sub 2}S and HCl, which attack metal components of the coal gas train, causing plant downtime and increasing the cost of power generation. Corrosion-resistant coatings would improve plant availability and decrease maintenance costs, thus allowing the environmentally superior integrated-gasification-combined-cycle (IGCC) plants to be more competitive with standard power-generation technologies. Heat-exchangers, particle filters, turbines, and other components in the IGCC system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy will improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. The Fe- and Ni-based high-temperature alloys are susceptible to sulfidation attack unless they are fortified with high levels of Cr, Al, and Si. To impart corrosion resistance, these elements need not be in the bulk of the alloy and need only be present at the surface layers. In this study, the use of corrosion-resistant coatings on low alloy steels was investigated for use as high-temperature components in IGCC systems. The coatings were deposited using SRI's fluidized-bed reactor chemical vapor deposition technique. Diffusion coatings of Cr and Al were deposited by this method on to dense and porous, low alloy stainless steel substrates. Bench-scale exposure tests at 900 C with a simulated coal gas stream containing 1.7% H{sub 2}S showed that the low alloy steels such SS405 and SS409 coated with {approx}20%Cr and Al each can be resistant to sulfidation attack for 500 h. However, exposure to an actual coal gasifier gas stream at the Wabash River gasifier facility for 1000 h in the temperature range 900 to 950 C indicated that Cr and Al present in the coating diffused further into the substrate decreasing the protective ability of these elements against attack by H{sub 2}S. Similarly, adherent multilayer coatings containing Si, Ti, Al, and Nb were also deposited with subsequent nitridation of these elements to increase the corrosion resistance. Both dense and porous SS409 or SS 410 alloy substrates were coated by using this method. Multilayer coatings containing Ti-Al-Si nitrides along with a diffusion barrier of Nb were deposited on SS410 and they were found also to be resistant to sulfidation attack in the bench scale tests at 900 C. However, they were corroded during exposure to the actual coal gasifier stream at the Wabash River gasifier facility for 1000 h. The Cr/Al coatings deposited inside a porous substrate was found to be resistant to sulfidation attack in the bench-scale simulated tests at 370 C. The long-term exposure test at the Wabash River gasifier facility at 370 C for 2100 h showed that only a minor sulfidation attack occurred inside the porous SS 409 alloy coupons that contained Cr and Al diffusion coatings. This attack can be prevented by improving the coating process to deposit uniform coatings at the interior of the porous structure. It is recommended that additional studies be initiated to optimize the FBR-CVD process to deposit diffusion coatings of the corrosion resistant elements such as Cr, Al, and Ti inside porous metal filters to increase their corrosion resistance. Long-term exposure tests using an actual gas stream from an operating gasifier need to be conducted to determine the suitability of the coatings for use in the gasifier environment.

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Report No.: None
  • Grant Number: FC26-03NT41616
  • DOI: 10.2172/926667 | External Link
  • Office of Scientific & Technical Information Report Number: 926667
  • Archival Resource Key: ark:/67531/metadc901387

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • May 31, 2007

Added to The UNT Digital Library

  • Sept. 27, 2016, 1:39 a.m.

Description Last Updated

  • May 8, 2018, 1:33 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 4
Total Uses: 25

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

International Image Interoperability Framework

IIF Logo

We support the IIIF Presentation API

Krishnan, Gopala N.; Malhotra, Ripudaman; Perez, Jordi; Hornbostel, Marc; Lau, Kai-Hung & Sanjurjo, Angel. Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems, report, May 31, 2007; Menlo Park, California. (digital.library.unt.edu/ark:/67531/metadc901387/: accessed October 22, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.