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Thermodynamic and emission characteristics of a hydrogen-enriched natural gas-fired boiler integrated with external flue gas recirculation and waste heat recovery.
- Source :
-
Applied Energy . Mar2024, Vol. 358, pN.PAG-N.PAG. 1p. - Publication Year :
- 2024
-
Abstract
- Hydrogen-enriched natural gas (HENG) is a low-carbon fuel and its utilization in combustion devices has been under extensive discussion recently as it is a promising way to reduce the CO 2 emission during combustion. The applicability of HENG in the existing natural gas-fired combustion equipment in terms of its efficiency and emissions attracts increasing attention, especially for industrial and domestic small-scale boilers. In this study, the thermal efficiency and pollutant emissions of a 4.2 MW th HENG-fired boiler integrated with external flue gas recirculation (FGR) were respectively evaluated based on the thermodynamic and heat transfer models and the Chemical Reaction Network model. Results suggested that NOx emission rose by ∼19% as the hydrogen volumetric fraction in the fuel increased from 0 to 0.4 at a constant excess air ratio and FGR rate. To suppress the NOx rise, the FGR rate was tuned higher while the system thermal efficiency decreased subsequently. To further improve the overall system thermal efficiency, a cascade flue gas waste heat recovery strategy including sensible heat recovery using an external economizer and latent heat recovery using dual-spray heat exchangers was proposed. The thermodynamic analysis demonstrated that the external economizer improved the overall system thermal efficiency by 0.4% - 0.7% and the dual-spray heat exchangers promoted the overall system thermal efficiency by over 5%. Thus, a comprehensive performance optimization strategy was developed for HENG-fired boilers in terms of their overall system thermal efficiency promotion, NOx emission control, and CO 2 emission reduction. • The effects of hydrogen addition on the gas-fired boiler performance were assessed. • Thermodynamic and heat transfer models were established to study the boiler efficiency. • The Chemical Reaction Network model was used to study pollutant emissions. • Flue gas recirculation technology was applied to suppress the NOx emission. • A cascade flue gas waste heat recovery strategy was proposed and confirmed. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 03062619
- Volume :
- 358
- Database :
- Academic Search Index
- Journal :
- Applied Energy
- Publication Type :
- Academic Journal
- Accession number :
- 175298826
- Full Text :
- https://doi.org/10.1016/j.apenergy.2023.122614