A salt-induced mechanism for the swelling of black liquor droplet during devolatilization

Chen, Chengcong; Alén, Raimo; Lehtimäki, Esa; Louhelainen, Jarmo

doi:10.1016/j.fuel.2017.04.045

Cited by 6 publications

(6 citation statements)

References 21 publications

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“…A similar trend has been observed previously (Alén 1994). Such a difference might be associated with the fact that HW lignin contains higher amounts of carbohydrates which facilitate the swelling of BL droplets during combustion (Chen et al 2017).…”

Section: Resultsmentioning

confidence: 99%

Role of lignin and sodium carbonate on the swelling behavior of black liquor droplets during combustion

2018

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A partial removal of lignin from black liquor (BL) by carbonation and lignin precipitation was studied. In lignin-lean BL droplets during combustion in a laboratory furnace at 800°C in stagnant air, the maximum swelling was decreased. This observation was interpreted as showing that the lignin content decrement is due mainly to removal of higher molar mass (HMM) lignin and that the Na2CO3content of the BL is increased. Stepwise precipitation experiments with industrial softwood and hardwood kraft BLs by carbonation (resulting in pH decrement from 13 to 9) indicated that a fraction of HMM lignin (MM >10 kDa) with a higher amount of carbohydrates precipitated more prominently and earlier than the fraction with lower molar mass (LMM) lignin (MM <10 kDa) containing less amounts of carbohydrates. Separate experiments with a 50/50 (by wt) mixture of different lignin fractions (1–5, 5–10 and >10 kDa) and BL-originated aliphatic carboxylic acids were performed and found that the mixture of medium MM fraction (MM 5–10 kDa) swelled more than the other lignin fractions. The addition of Na2CO3to BL also reduced the maximum swelling of a BL droplet.

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Section: Resultsmentioning

confidence: 99%

Role of lignin and sodium carbonate on the swelling behavior of black liquor droplets during combustion

2018

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“…The organic part consists of dissolved lignin, aliphatic carboxylic acids, and other organics such as polysaccharides and extractives. 22 The inorganic part originating from the pulping chemicals include, e.g., sodium hydroxide, sodium sulfide, sodium sulfate, sodium thiosulfate, and sodium carbonate, 23 as well as sodium bound to organics from the wood. 22 The black liquor used in the present study originated from the Smurfit Kappa mill in Piteå, Sweden, which produces Kraftliner from mostly virgin wood fibers through the Kraft process.…”

Section: Methodsmentioning

confidence: 99%

“…22 The inorganic part originating from the pulping chemicals include, e.g., sodium hydroxide, sodium sulfide, sodium sulfate, sodium thiosulfate, and sodium carbonate, 23 as well as sodium bound to organics from the wood. 22 The black liquor used in the present study originated from the Smurfit Kappa mill in Piteå, Sweden, which produces Kraftliner from mostly virgin wood fibers through the Kraft process. The batch of black liquor was obtained from a position just upstream of the fuel injection point of the recovery boiler.…”

Section: Methodsmentioning

confidence: 99%

Inorganic Chemistry during Pyrolysis, Gasification, and Oxyfuel Combustion of Kraft Pulping Black Liquor

Weiland,

Jacobsson,

Wahlqvist

et al. 2024

Energy Fuels

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Changed utilization of black liquor in the pulp and paper industry has the potential to offer simplified carbon capture and, thus, negative net emissions from these large point sources. This can be achieved either by adapting existing recovery boilers to oxyfuel combustion or by replacing them with black liquor gasification technology. In this work, the chemistry during black liquor conversion was therefore studied in detail under different atmospheres relevant for pyrolysis, gasification, and oxyfuel combustion. Experiments were performed using environmental scanning transmission electron microscopy (ESTEM) and thermogravimetric analysis (TGA), supported with thermodynamic equilibrium calculations (TECs) to understand and interpret the results. Black liquor conversion was found to be generally similar in air and oxyfuel atmospheres containing approximately 20−25 mol % oxygen. The results however indicated that there was a higher probability of forming carbonates in the melt at higher carbon dioxide (CO 2 ) partial pressures, which in addition was found to be associated with potentially higher sulfur loss during black liquor conversion. Both of these characteristics can negatively affect the chemical recycling at the pulp mill by increasing the need for lime and makeup chemicals.

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“…We speculate that this was because a plastic state layer formed from salt-polymer mixtures in the black liquor it was heated. 11 This plastic state layer hinders the release of volatile components, and the accumulation of unreleased volatile components in the fuel causes expansion and swelling behavior in the following stages. This phenomenon cannot be directly observed even in the single pellet combustion experiment due to the flame.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%

“…Alén 10 compared and discussed the swelling behavior of pine and birch kraft black liquors and their main organic components. Chen et al 11 stated the three basic factors that account for the swelling of black liquor droplets: the production of volatiles, the formation of a rigid char surface, and the creation of a plastic state.…”

Section: Introductionmentioning

confidence: 99%

Co‐combustion characteristics of black liquor and waste oil sludge

Chen

et al. 2021

Intl J of Energy Research

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In this study, the co-combustion of black liquor and oil sludge is investigated.The properties of the fuels are analyzed, and the co-combustion characteristics are explored by thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR). The synergistic effect, activation energy as well as gas yield are also studied from TG-FTIR results. The results show that the addition of oil sludge can promote the reaction in the early stage, as indicated by the combustion characteristic index and the flammability index. The TG-FTIR also shows that the swelling behavior of black liquor appears to block the release of volatile matter. The weaker SO 2 emission and XRF analysis for the black liquor indicate that most of the sulfur remained in the ash. A positive synergy effect existed in the early stage, and the activation energy decreased with the addition of oil sludge. Distinct stages could be observed in the single pellet combustion experiments. Adding oil sludge to the black liquor promoted surface bubbles and ash melting. Surface bubbles indicate more volatile breaks through the plastic state layer formed on the black liquor and increase the reaction. However, adding oil sludge should be controlled to reduce the hindrance to the reaction due to ash melting.

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A salt-induced mechanism for the swelling of black liquor droplet during devolatilization

Cited by 6 publications

References 21 publications

Role of lignin and sodium carbonate on the swelling behavior of black liquor droplets during combustion

Role of lignin and sodium carbonate on the swelling behavior of black liquor droplets during combustion

Inorganic Chemistry during Pyrolysis, Gasification, and Oxyfuel Combustion of Kraft Pulping Black Liquor

Co‐combustion characteristics of black liquor and waste oil sludge

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