Energy saving analysis and thermal performance evaluation of a hydrogen-enriched natural gas-fired condensing boiler |
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| Affiliation: | 1. State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi''an Jiaotong University, Xi''an, 710049, China;2. Zhejiang Academy of Special Equipment Science;1. Chemical Engineering Department, Faculty of Engineering, University of Isfahan, Isfahan, Iran;2. Hydrogen and Fuel Cell Research Laboratory, Department of Chemical Engineering, Faculty of Engineering, University of Kashan, Kashan, Iran;1. Key Laboratory of Bionic Engineering (Ministry of Education), College of Biological and Agricultural Engineering, Jilin University, Changchun, 130022, China;2. College of Bionics Science and Engineering, Jilin University, Changchun, 130022, China;1. National & Local Joint Engineering Research Center for Mineral Salt Deep Utilization, Huaiyin Institute of Technology, Huaian 223003, China;2. School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, China;1. School of Automotive Studies, Tongji University, Shanghai 201804, China;2. Chinesisch-Deutsches Hochschulkolleg, Tongji University, Shanghai 201804, China;1. Institute of Engineering Innovation, School of Engineering the University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan;2. Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505, Japan;3. Department of Systems and Control Engineering, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8550, Japan;4. Department of Mechanical Engineering, Tokyo Institute of Technology, O-okayama, Meguro-ku, 152-8550 Tokyo, Japan |
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| Abstract: | Hydrogen-enriched natural gas (HENG) has attracted widespread attention due to its lower pollutant emissions and industrial decarbonization in the past decades. HENG combustion boosts the water content in the flue gas, which is highly favorable for condensing boilers to recover additional latent heat. The energy saving and thermal performance of a condensing boiler burning HENG were evaluated at a constant heat load of 2.8 MW in this study. The variations in combustion products and boiler efficiency were investigated based on the material balance and energy conservation. The heat transfer calculations were employed to evaluate the thermal performance of boiler heating surfaces. The energy recovery performance of the condenser was assessed via a thermal design method. Results show that H2 enrichment enhances the radiation intensity of the flame due to the incremental triatomic gases with higher emissivity in the furnace. The heat absorption ratio increases with H2 enrichment in the radiative heating surface, while it shows a reverse tendency in the convective heating surface. The condensing boiler efficiency based on lower heating value increases from 101.83% to 110.60%, the total heat transfer rate of the condenser increases from 2.77 × 105 W to 4.61 × 105 W, and the total area required decreases from 46.45 m2 to 42.16 m2, as the H2 enriches from 0 to 100% under the exhaust flue gas temperature of 318 K. Although the amount of recoverable heat in the exhaust flue gas increases considerably after H2 blending, the original condenser with natural gas as the designed fuel could meet the requirements of the heat recovery for HENG without increasing the extra heating surface. When the H2 fraction is enriched from 0 to 100%, CO2 emission intensity drops from 6.05 × 10?8 kg J?1 to 0. This work may offer some theoretical references for the application and generalization of HENG condensing boilers. |
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| Keywords: | Hydrogen-enriched natural gas Energy saving Heat transfer Condensing boiler Condenser Carbon dioxide |
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