High Temperature Corrosion in Coal Combustion Systems

High-temperature corrosion in coal-fired power plants is a persistent challenge arising when boiler components are exposed to aggressive flue-gas constituents at elevated temperatures. Coal combustion generates complex mixtures of sulphur and chlorine species alongside fluctuating oxygen levels, which interact with metal surfaces to form corrosive scales and deposits. Sulphidation and oxidation processes dominate corrosion kinetics, leading to accelerated thinning of water-wall tubes, superheaters and reheaters. Local factors such as coal rank, mineral matter composition, combustion stoichiometry and gas flow dynamics govern the atmosphere at the metal–gas interface and thus the rate and type of corrosive attack. Mechanisms include sulfidic melting, under-deposit corrosion and mixed sulphide–oxide scale formation, all of which compromise thermal efficiency, increase maintenance costs and shorten component life. Mitigation strategies focus on fuel pretreatment to lower sulphur content, optimisation of air distribution to maintain favourable oxygen partial pressures, application of protective coatings and real-time diagnostic monitoring. Advances in corrosion-resistant alloys and ceramic barriers, combined with non-destructive evaluation and predictive modelling, are enhancing plant reliability. The global significance of this issue is underscored by its impact on energy security, greenhouse-gas emissions and the economic competitiveness of coal-based power generation.

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High Temperature Corrosion in Coal Combustion Systems publication trend

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Technical terms

High-temperature corrosion: Degradation of metal surfaces under exposure to aggressive combustion gases at temperatures generally above 500 °C.

Sulphidation: A corrosion process in which sulphur species react with metals to form metal sulphides, often accelerating material loss.

Computational Fluid Dynamics (CFD): Numerical simulation techniques for predicting fluid flow, heat transfer and chemical reactions within combustion systems.

Mixture fraction variance: A measure of local fuel–air mixing heterogeneity that influences flame structure and deposit formation.

Water wall tubes: Boiler tubes lining the furnace walls that absorb heat from combustion gases and are particularly susceptible to corrosion under reducing or sulfidising atmospheres.

References

1. Water Wall Tubes’ High Temperature Corrosion Root Cause Investigation: A 300 MW Level Boiler Case. Energies (2023).
2. Simulation Study of the Formation of Corrosive Gases in Coal Combustion in an Entrained Flow Reactor. Energies (2020).
3. Integrating Flow Field Dynamics and Chemical Atmosphere Predictions for Enhanced Sulfur Corrosion Risk Assessment in Power Boilers. Materials (2024).