Study of high-temperature oxygen combustion (HiTOx) and its heating performance using a laboratory-scale test furnace

Hisashi Nakamura, Yuji Kuwayama, Takakazu Onishi, Takuya Tezuka, Susumu Hasegawa, Kaoru Maruta, Tadahiro Araake, Susumu Mochida

Research output: Contribution to journalArticlepeer-review

Abstract

High-temperature air combustion technology (HiCOT), which uses air preheated by heat recirculation, has had a great impact on reduction of CO2 and NOx emissions from combustion furnaces. In this study, a lab-scale test furnace was developed to examine the novel combustion method termed as high-temperature oxygen combustion, HiTOx. HiTOx uses combustion with a preheated mixture of oxygen and burned gas. Testing was conducted with liquefied petroleum gas. HiTOx has the following three characteristics because nitrogen is excluded from the working gas: (1) in principle, no thermal NOx is generated; (2) combustion gas is almost entirely water vapor and carbon dioxide, providing better heating performance because of its strong gas-phase radiation; and (3) the method has good compatibility with carbon dioxide capture, utilization and storage (CCUS) technologies because carbon dioxide can be separated easily from the combustion gas of HiTOx furnace by condensation of water vapor. Heating performance tests in a lab-scale test furnace were conducted using stainless steel rectangular rods as heating objects. Gas temperature, object temperature, and heat fluxes on the objects were measured. Compared to HiCOT, HiTOx enables stable operation with a lower flow rate of flue gas, better gas temperature uniformity in the furnace, faster heating, and higher heat flux. The heat flux of HiTOx was slightly higher than that of HiCOT (7%) when the furnace temperature was low (973 K) and the temperature difference between the gas and object was large (280 K). On the other hand, the heat flux of HiTOx was much higher than that of HiCOT (22%) when the furnace temperature was high (1323 K) and the temperature difference was small (60 K). Radiative heat transfer at high temperature was greater in HiTOx than in HiCOT at small temperature difference between the gas and object. A furnace body can be greatly downsized by the good radiation performance of combustion gas in HiTOx, resulting in a remarkable improvement in energy-saving performance.

Original languageEnglish
Article number117077
JournalApplied Thermal Engineering
Volume194
DOIs
Publication statusPublished - 2021 Jul 25

Keywords

  • Moderate or Intense Low-oxygen Dilution (MIDL) combustion
  • Oxy-fuel combustion
  • Oxy-steam combustion
  • Wet-CO recycle

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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