The influence of potassium-rich biomass ashes on steel corrosion above 550 °C. (1st May 2019)

• Record Type: Journal Article
• Authors: Mlonka-Mędrala, Agata; Magdziarz, Aneta; Kalemba-Rec, Izabela; Nowak, Wojciech
• Is Part Of: Energy conversion and management. Volume 187(2019)
• Page Start: 15
• Page End: 28
• Publication Date: 2019-05-01
• Subjects: Biomass ash deposits -- Alkali metals -- High-temperature corrosion -- SEM-EDS; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2019.02.074
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: Agricultural biomass ashes were K-rich ashes. Corrosion of steels under biomass ash deposits took place. SEM-EDS investigation of corrosion was used to observe oxide scales. Impact of chromium content in steel on corrosion was observed. Addition of KCl to biomass ash significantly accelerated the corrosion rate. Abstract: The slagging, fouling and high temperature corrosion are major problems in biomass-firing units and lead to heat transfer limitation, bed agglomeration and metal surface degradation. This paper reports the results of the laboratory-scale corrosion studies of selected steel grades (16Mo3, 10CrMo9–10, X10CrMoVNb9–1, X7CrNiNb18–10) under biomass ash deposits. Five biomass ashes (3 agricultural biomass and 2 energy crops) were used for corrosion tests. Selected samples were doped with 0.1 and 0.5% wt. of KCl to simulate salt condensation process occurring in a real boiler. The corrosion experiments were carried out under oxidizing conditions, at 560 °C and 610 °C for 168 h. To determine the corrosion rate the mass of steel samples were measured after 24, 72 and 168 h. The corrosion products were analysed using SEM-EDS technique. The results showed that oxide scale formation rate determines the overall corrosion mechanism and the influence of ash deposits on steel. For low-chromium steels the oxidation rate is significant and a scale is a protective barrier between the deposit and metal surface limiting further oxidation process. The highest influence of ash on corrosion process was observed for high-chromium steels. However, high-chromium steels show the highest corrosion resistance.