Soot Concentrations in an Atmospheric Entrained Flow Gasifier with Variations in Fuel and Burner Configuration Studied Using Diode-Laser Extinction Measurements

Simonsson, Johan; Bladh, Henrik; Gullberg, Marcus; Pettersson, Esbjörn; Sepman, Alexey; Ögren, Yngve; Wiinikka, Henrik; Bengtsson, Per Erik

doi:10.1021/acs.energyfuels.5b02561

Cited by 30 publications

(21 citation statements)

References 34 publications

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“…Simonsson et al [39] reported an atmospheric entrained flow gasifier experiment with stem wood and peat as fuels. A similar but somewhat simplified simulation setup is configured as seen in Fig.…”

Section: Figmentioning

confidence: 99%

Eulerian-Lagrangian simulation of pulverized biomass jet using spheroidal particle approximation

Guo

Zhao

et al. 2019

Fuel

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Pulverized biomass has great potential to replace coal in the many industrial systems such as suspensionfiring furnace and entrained-flow gasifier. The shape of pulverized biomass deviates significantly from the quasi-spherical coal particle. However, it is common to simulate pulverized biomass particles as spheres as most biomass models are developed based on coal models. With the aim to obtain a more realistic simulation of pulverized biomass, this work extends the treatment of pulverized biomass to spheroids. A spheroid model that accounts for spheroidal particle drag force and torque is implemented into an Eulerian-Lagrange computational fluid dynamic solver. Comprehensive verifications and validations are performed by comparing with experiments and direct numerical simulations.Furthermore, non-reactive simulations of a lab-scale entrained flow gasifier are carried out using both the conventional spherical particle model, simplified non-sphere model, and the implemented detailed spheroidal particle model. By studying the simulation results of particle and fluid velocities in axial, radial and tangential directions, differences are observed when comparing the sphere model, the simplified non-sphere model, and the spheroid model. The spheroid model also indicates that particle orientation, which is ignored in the sphere model and the simplified non-sphere model, plays a role in the behavior of the particle dynamics. It is also found that, under such conditions, the spheroid model, compared to the sphere model, yields a more dispersed distribution regarding the particle residence time and local concentration. These non-reactive simulation results imply that shortcomings may exist in the common practice of simulating conversion of pulverized biomass in which the sphere model or the simplified non-sphere model is applied.

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Section: Figmentioning

confidence: 99%

Eulerian-Lagrangian simulation of pulverized biomass jet using spheroidal particle approximation

Guo

Zhao

et al. 2019

Fuel

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“…In the case of Peat, higher wavelengths give higher soot concentrations, whereas the behavior is opposite for Wood. Previous studies on Wood [17] revealed that the soot aerodynamic diameter increases gradually with decreasing lambda and is at least a factor of 2 larger than for Peat. This suggests that, for Wood, the Rayleigh criterion is violated at 639 nm and that the contribution of scattering to the reduction in transmittance of Sensor 3 can explain the difference to Sensors 1 and 2.…”

Section: Soot and Carbon Conversionmentioning

confidence: 83%

“…1) operated at 0.1 MWth [17]. The gasifier has the shape of a standing cylinder with flat top and conical bottom.…”

Section: Reactor Facilitymentioning

confidence: 99%

Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier

Sepman¹,

Ögren²,

et al. 2017

Proceedings of the Combustion Institute

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Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier. Proceedings of the Combustion AbstractTunable diode laser absorption spectroscopy (TDLAS) was used to measure several important process parameters at two different locations inside the reactor of an atmospheric, air-blown 0.1 MWth biomass gasifier. Direct TDLAS at 2298 nm was employed for carbon monoxide (CO) and water vapor (H2O), calibration-free scanned wavelength modulation spectroscopy at 1398 nm for H2O and gas temperature, and direct TDLAS at 770 nm for gaseous elemental potassium, K(g), under optically thick conditions.These constitute the first in situ measurements of K(g) and temperature in a reactor core and in biomass gasification, respectively. In addition, soot volume fractions were determined at all TDLAS wavelengths, and employing fixed-wavelength laser extinction at 639 nm. Issues concerning the determination of the actual optical path length, as well as temperature and species non-uniformities along the line-of-sight are addressed. During a 2-day measurement campaign, peat and stem wood powder were first combusted at an air equivalence ratio (lambda) of 1.2 and then gasified at lambdas of 0.7, 0.6, 0.5, 0.4 and 0.35.Compared to uncorrected thermocouple measurements in the gas stream, actual average temperatures in the reactor core were significantly higher. The CO concentrations at the lower optical access port were comparable to those obtained by gas chromatography at the exhaust. In gasification mode, similar H2O values were obtained by the two different TDLAS instruments. The measured K(g) concentrations were compared to equilibrium calculations. Overall, the reaction time was found to be faster for peat than for stem wood. All sensors showed good performance even in the presence of high soot concentrations, and real-time detection was useful in resolving fast, transient behaviors, such as changes in stoichiometry.Practical implications of in-situ TDLAS monitoring on the understanding and control of gasification processes are discussed.

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“…The extinction measurement system was an extended version of a previous system developed for in-situ flame measurements (Simonsson et al 2015), as well as practical combustion and gasification devices (Simonsson et al 2016). In the present setup a four-wavelength version was used.…”

Section: Diagnostic Methodsmentioning

confidence: 99%

Investigation of the absorption Ångström exponent and its relation to physicochemical properties for mini-CAST soot

Török

Malmborg

Simonsson

et al. 2018

Aerosol Science and Technology

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In this work, a mini-CAST soot generator was used to produce soot with different optical and physicochemical characteristics. Absorption A ngstr€ om exponents (AAE) expressing the absorption wavelength dependence were assessed by multiwavelength in-situ and filter-based (aethalometer) laser extinction. The two optical techniques showed good agreement. For the chosen mini-CAST operating conditions, AAEs between 1 and 3.5 were found. Soot with high mass-fractions of organic carbon (OC) and pyrolytic carbon (PC) determined with thermal optical analysis were associated with AAEs significantly higher than 1. Heating to 250 and 500 C removed the majority of polycyclic aromatic hydrocarbons. However, the thermal-optical analysis revealed that OC and PC were abundant in the soot with AAE > 2 also after heating the aerosol. Analysis of mass absorption cross section ratios for elemental carbon and OC indicated that elevated AAEs also after heating to 500 C could be related to persistent OC and PC components and/or the refractory soot. By comparing the mini-CAST soot optical properties with soot properties derived from in-situ extinction measurements in a premixed flame, mini-CAST soot with a higher AAE could be identified as less mature soot.

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Soot Concentrations in an Atmospheric Entrained Flow Gasifier with Variations in Fuel and Burner Configuration Studied Using Diode-Laser Extinction Measurements

Cited by 30 publications

References 34 publications

Eulerian-Lagrangian simulation of pulverized biomass jet using spheroidal particle approximation

Eulerian-Lagrangian simulation of pulverized biomass jet using spheroidal particle approximation

Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier

Investigation of the absorption Ångström exponent and its relation to physicochemical properties for mini-CAST soot

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