ESSC & DUPLEX 2019

In view of the increasing pressures to reduce greenhouse gases, and in general the use of coal as a fossil fuel it could be expected that the future of coal-based power plants be very short. However, the technical solutions provided to improve the efficiency, as well as the improvements in the technology of production and capture of CO2 have made the IGCC and IGFC plants back on paper as a viable technological solution for a “cleaner” production of energy. USA with the construction of the Edwardsport and Kemper plants and Japan with Nasoko and Osaki are a clear example of the commitment to this technology at a time when coal seemed to have been buried again. Although it is true that in Spain the only IGSCC plant, operated by ENDESA in Puertollano, was closed in August 2015, it is also true that has been acquired experience in operation and in the problems associated with the management of its materials over more than 15 years that should be considered for the design and operation of future installations and developments in these or other power generation systems. This work describes the corrosion problems found in the synthesis gas cleaning system and the tests carried out by CIEMAT under simulated operating conditions on a super-austenitic stainless steel (904L: UNS S08904) and a super duplex steel (Zeron 100: UNS S32760) as alternative materials to 316L steel stabilized with Ti, used as a replacement for the original carbon steel, cracked in service by SCC, which finally justified its replacement. There was no cracking indication by SCC under simulated conditions of operation in any of the materials, although there was loss of material by corrosion. Kinetic corrosion curves were obtained for each tested material. Although no growth of cracks has been detected by SCC, its appearance in service is not ruled out given the high sensitivity to small local changes in chloride/sulphide concentration in the environment. From the point of view of corrosion resistance 316 Ti and 904L are comparable, however Zeron 100 has shown lower resistance.