Process simulation of co-firing torrefied biomass in a 220 MWe coal-fired power plant

Jun Li, Xiaolei Zhang, Halina Pawlak-Kruczek, Weihong Yang, Pawel Kruczek, Wlodzimierz Blasiak

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33 Citations (Scopus)
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Abstract

Torrefaction based co-firing in a pulverized coal boiler has been proposed for large percentage of biomass co-firing. A 220 MWe pulverized coal-power plant is simulated using Aspen Plus for full understanding the impacts of an additional torrefaction unit on the efficiency of the whole power plant, the studied process includes biomass drying, biomass torrefaction, mill systems, biomass/coal devolatilization and combustion, heat exchanges and power generation. Palm kernel shells (PKS) were torrefied at same residence time but 4 different temperatures, to prepare 4 torrefied biomasses with different degrees of torrefaction. During biomass torrefaction processes, the mass loss properties and released gaseous components have been studied. In addition, process simulations at varying torrefaction degrees and biomass co-firing ratios have been carried out to understand the properties of CO2 emission and electricity efficiency in the studied torrefaction based co-firing power plant. According to the experimental results, the mole fractions of CO 2 and CO account for 69-91% and 4-27% in torrefied gases. The predicted results also showed that the electrical efficiency reduced when increasing either torrefaction temperature or substitution ratio of biomass. A deep torrefaction may not be recommended, because the power saved from biomass grinding is less than the heat consumed by the extra torrefaction process, depending on the heat sources.

Original languageEnglish
Pages (from-to)503-511
Number of pages9
JournalEnergy Conversion and Management
Volume84
Early online date16 May 2014
DOIs
Publication statusPublished - 31 Aug 2014

Keywords

  • biomass
  • co-firing
  • torrefaction
  • CO2 reduction
  • CO2 emissions

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