On the particle sizing of torrefied biomass for co-firing with pulverized coal

Panahi, Aidin; Tarakcioglu, Mahmut; Schiemann, Martin; Delichatsios, Michael; Levendis, Yiannis A.

doi:10.1016/j.combustflame.2018.04.014

Cited by 66 publications

(31 citation statements)

References 74 publications

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“…For example, Saastamoinen et al [6] compared the single particle burning of pulverized wood to that for coal in the reaction condition of a large utility boiler, and concluded that a 500 µm wood particle has the same burnout time as that of a 200 µm Polish coal particle. Panahi et al [7] showed that torrefied biomass of 212-300 µm has a burnout time similar to that of 75-90 µm coal particles measured in a drop tube furnace at 1350 K. Magalhães et al [8] reported that the burnout time of agricultural residue sieved to 212-300 µm was comparable to two lignite coals of 106-125 µm. The burnout time of the biomass particles was influenced to a greater extent by the char conversion than the devolatilization, especially in the case of large particles [9,10].…”

Section: Introductionmentioning

confidence: 87%

Reduction of Unburned Carbon Release and NOx Emission from a Pulverized Wood Pellet Boiler Retrofitted for Fuel Switching from Coal

Lee

Park

et al. 2020

Energies

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For renewable electricity production, biomass can fully displace coal in an existing power plant with some equipment modifications. Recently, a 125 MWe power plant burning mainly anthracite in Korea was retrofitted for dedicated wood pellet combustion with a change of boiler configuration from arch firing to wall firing. However, this boiler suffers from operational problems caused by high unburned carbon (UBC) contents in the bottom ash. This study comprises an investigation of some methods to reduce the UBC release while achieving lower NOx emissions. The computational fluid dynamics approach was established and validated for typical operating data. Subsequently, it was applied to elucidate the particle combustion and flow characteristics leading to the high UBC content and to evaluate the operating variables for improving the boiler performance. It was found that the high UBC content in the bottom ash was a combined effect of the poor fuel grindability and low gas velocity in the wide burner zone originating from the arch-firing boiler. This prevented the operation with deeper air staging for lower NOx emissions. Reducing the particle size to <1.5 mm by modifying mills or pretreating the fuel using torrefaction was the only effective way of lowering the UBC and NOx emissions with deeper air staging while increasing the boiler efficiency.

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Section: Introductionmentioning

confidence: 87%

Reduction of Unburned Carbon Release and NOx Emission from a Pulverized Wood Pellet Boiler Retrofitted for Fuel Switching from Coal

Lee

Park

et al. 2020

Energies

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“…A pulverizing mill (Raymond mill) was used here to pulverize the Australian coal. Then, the coal particles were sieved and selected to ensure a suitable size of 75 µm (200 mesh), based on the industry standard [33]. Finally, the pulverized fuels were introduced into the combustion chamber by primary air/RFG and combusted with secondary air (or a mixture of O 2 and RFG).…”

Section: Methodsmentioning

confidence: 99%

Oxy-Fuel Combustion Characteristics of Pulverized Coal under O2/Recirculated Flue Gas Atmospheres

2020

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Oxy-fuel combustion is an effective technology for carbon capture and storage (CCS). Oxy-combustion for coal-fired power stations is a promising technology by which to diminish CO2 emissions. Unfortunately, little attention has been paid to the oxy-combustion characteristics affected by the combustion atmosphere. This paper is aimed at investigating the oxy-fuel combustion characteristics of Australian coal in a 0.3 MWth furnace. In particular, the influences of various oxygen flow rates and recirculated flue gas (RFG) on heating performance and pollutant emissions are examined in O2/RFG environments. The results show that with increases in the secondary RFG flow rate, the temperatures in the radiative and convective sections decrease and increase, respectively. At a lower oxygen flow rate, burning Australian coal emits lower residual oxygen and NO concentrations. In the flue gas, a high CO2 concentration of up to 94.8% can be achieved. Compared to air combustion, NO emissions are dramatically reduced up to 74% for Australian coal under oxy-combustion. Note that the high CO2 concentrations in the flue gas under oxy-coal combustions suggest great potential for reducing CO2 emissions through carbon capture and storage.

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“…Upon reaching the final temperature, each sample was treated at constant conditions for 30 min. All torrefied biomass fuels were air-dried, chopped in a household blender, and size classified by sieving to obtain size cuts of (212-300 µm) based on the findings of previous study in this laboratory [23,24]. In a different study [25], it was observed that the torrefaction process reduced the particle aspect ratios and enhanced the uniformity of particle sizes.…”

Section: Preparation Of Samplesmentioning

confidence: 99%

“…Fuel particles were introduced through a hole on the top of the injector, by placing a small number of particles at the tip of a beveled needle syringe, introducing the needle into the injector hole and giving it a gentle tap until single particles were seen burning in the furnace. Pyrometric observations of those particles were conducted from the top of the furnace injector, details of the pyrometer optics, electronics, calibration, and performance were given in [23,[27][28][29]]. An Edgertronic Self-Contained Digital High-Speed Broadband video camera was used, at speeds of 2000 frames per second.…”

Section: 2experimental Apparatus and Proceduresmentioning

confidence: 99%

Oxy-combustion Behavior of Torrefied Biomass Particles

Panahi¹,

Toole²,

Yang³

et al. 2019

Preprint

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A fundamental investigation was conducted on the combustion characteristics of torrefied biomass in both air and O2/CO2 gases containing 21% or 30% oxygen mole fractions. These gases simulated oxy-combustion environments. The targeted torrefied biomass types were waste crops, both herbaceous and woody. The experimental setup that was used in this investigation consisted of a drop-tube furnace, operated at a wall temperature of 1400 K, a high-speed high-resolution camera. Entire luminous particle combustion profiles of single particles were recorded by means of highspeed high-resolution cinematography. Combustion of these particles took place in two phases. Initially, volatiles evolved and burned in spherical/ellipsoidal envelope flames; then, upon extinction of these flames, char residues ignited and burned. Replacing air as the furnace background gas with 21%O2-79%CO2 reduced the luminosity of flame and the lengthened the burnout times; and increasing the oxygen mole fraction further to 30% increased the luminosity of the flame and shortened the burnout times.

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On the particle sizing of torrefied biomass for co-firing with pulverized coal

Cited by 66 publications

References 74 publications

Reduction of Unburned Carbon Release and NOx Emission from a Pulverized Wood Pellet Boiler Retrofitted for Fuel Switching from Coal

Reduction of Unburned Carbon Release and NOx Emission from a Pulverized Wood Pellet Boiler Retrofitted for Fuel Switching from Coal

Oxy-Fuel Combustion Characteristics of Pulverized Coal under O2/Recirculated Flue Gas Atmospheres

Oxy-combustion Behavior of Torrefied Biomass Particles

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