The effect of Co-firing with Straw and Coal on High Temperature Corrosion

Melanie Montgomery, Flemming Frandsen, OH Larsen

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

As a part of ELSAMS development programme into alternative energy sources, various concepts of straw-firing have been investigated. This paper concerns co-firing of straw with coal to reduce the corrosion rate observed in straw-fired power plants. Co-firing with coal reduces the amount of potassium chloride deposited onto superheater sections which causes accelerated corrosion by chlorination. A field investigation at Midtkraft Studstrupværket in Denmark has been undertaken where coal with 10% straw and 20% straw (% energy basis) has been used as fuel for up to 3000 hours. The study was undertaken by: a) the exposure of metal rings on water/air cooled probes, and b) the exposure of a range of materials built into the existing superheaters. A range of austenitic and ferritic steels was exposed in the steam temperature region of 520-580°C. The flue gas temperature ranged from 925-1100°C. The corrosion products for the various steel types were investigated using light optical and scanning electron microscopy. Corrosion mechanisms for the austenitic and ferritic steels are presented. These are discussed in relation to temperature and deposit composition. Co-firing with coal has removed potassium chloride from the deposit thus chlorination is not a corrosion form that is seen. An increase in straw share from 10 % to 20 % (% energy basis) gave a higher amount of potassium sulphate in the ash and consequently greater amount of sulphidation. At high metal and flue gas temperatures, low temperature hot corrosion was also observed.
Original languageEnglish
Title of host publicationEffects of coal Quality on power plants
EditorsAK Mehta and SA Benson
Place of PublicationPalo Alto
PublisherEPRI
Publication date2001
Publication statusPublished - 2001
EventEffects of coal quality on Power Plant Management - United Engineering foundation conference - Park City, Utah, USA
Duration: 1 Jan 2001 → …

Conference

ConferenceEffects of coal quality on Power Plant Management - United Engineering foundation conference
CityPark City, Utah, USA
Period01/01/2001 → …

Keywords

  • Corrosion

Cite this

Montgomery, M., Frandsen, F., & Larsen, OH. (2001). The effect of Co-firing with Straw and Coal on High Temperature Corrosion. In AK. M. A. SA. B. (Ed.), Effects of coal Quality on power plants EPRI.