Numerical investigation on H₂S formation characteristics in air-staging combustion of a tangentially coal-fired boiler

ABSTRACT

Existing H₂S generation models are mainly applied in laboratory-scale models and thoughtless about the fuel sulfur release characteristics in fuel-rich zone. So, a novel H₂S generation model is proposed for describing the H₂S formation characteristics of real-scale boilers in this work. It consists of two parts: fuel sulfur release and chemical reactions. The ratio of the gasification rate to the consumption rate for each char particle is calculated in coal combustion model through the user-defined function (UDF) approach, which is delivered to the H₂S generation model for determining the proportions of char sulfur converted to COS and SO₂. The numerical results show that the proportions of char sulfur converted to H₂S are about 0.545 over the excess air coefficient range from 0.6 to 1.2. The strongly reducing atmosphere could just accelerate the H₂S formation to a certain extent in the devolatilization stage. For a 600 MW tangentially coal-fired boiler, the H₂S concentration over 400 mg∙kg⁻¹ appears mainly in the zone below burner A and the zone between burner E and the separated over-fire air nozzle. This study is intended to guide for predicting possible corrosion zone and delivering targeted solutions for inhibiting metal corrosion.

KEYWORDS:

• High-temperature corrosion
• air-staging combustion
• H₂S formation
• numerical simulation
• tangentially-fired boiler

Nomenclature

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Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work has been financially supported by the China-CEEC Joint Higher Education Project (Cultivation Project) (CEEC2021001). Srdjan Belošević and Ivan Tomanović acknowledge the financial support by the Ministry of Education, Science and Technological Development of the Republic of Serbia.