Effects of the bubbles in slag on slag flow and heat transfer in the membrane wall entrained-flow gasifier

Zhang, Binbin; Shen, Zhongjie; Han, Dong; Liang, Qinfeng; Xu, Jianliang; Liu, Haifeng

doi:10.1016/j.applthermaleng.2016.10.141

Cited by 20 publications

(17 citation statements)

References 29 publications

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“…The control volume related to the flow and heat transfer process can be divided into liquid slag, solid slag, SiC refractory wall, and metal wall. The slag flow and heat transfer model were established according to the Segginai 15 method and our previous study, 30 which mainly includes momentum conservation equation, mass conservation equation, energy conservation equation, and some other related equations.…”

Section: Model Descriptionmentioning

confidence: 99%

“…In addition, Table 1 shows the model parameters and boundary conditions. According to the previous study, 30 the dimension of the gasifier and refractory wall parameter are given and the thermal conductivity of metal wall and refractory wall are considered as constant. The cooling water temperature is considered as constant and approximately equal to the metal wall–water interface temperature.…”

Section: Model Descriptionmentioning

confidence: 99%

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Modeling Study of the Slag Behaviors Based on Temperature–Time–Viscosity of Crystalline Slag in an Entrained-Flow Gasifier

et al. 2022

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The crystal growth process has an important influence on the viscosity of the slag, which affects the characteristics of the slag layer on the wall of the gasifier. The slag flow and heat transfer model based on temperature–time–viscosity of crystalline slag were established, to predict the slag behaviors and protect gasifier. The results showed the overall viscosity of the slag after considering the residence time effect was higher than that when using the measured viscosity–temperature curve value. The liquid slag thickness, solid slag thickness, and residence time increased after the slag viscosity amendment, while the slag flow velocity and heat flux density decreased. Moreover, several types of crystallized slag were constructed to study the effects of crystal morphology and degree of crystallization difficulty on slag behaviors. The result indicated that the difficulty and crystal morphology of the slag crystallization cannot be ignored when using crystallized slag in gasification.

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Section: Model Descriptionmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

Modeling Study of the Slag Behaviors Based on Temperature–Time–Viscosity of Crystalline Slag in an Entrained-Flow Gasifier

et al. 2022

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“…From the cross-section, the top cone wall is composed of four parts in turn: a liquid slag layer, a solid slag layer, a SiC refractory wall layer, and a metal wall layer. According to previous studies, , several main assumptions were used in this study: (1) the liquid–solid slag interface temperature is considered as T cv , and molten slag is regarded as Newtonian fluid when the temperature is above T cv ; (2) the temperature profile across the slag layer is linear; (3) the sheering effect of gas flow on the slag layer surface is ignored; (4) the heat transfer direction is mainly perpendicular to the wall. Thus, the slag flow and heat transfer model at the steady state were established based on some governing equations about mass conservation, momentum conservation, and energy conservation.…”

Section: Model Descriptionmentioning

confidence: 99%

“…The interface temperature of the solid–liquid slag layer was defined as slag flow temperature instead of T cv in a modified model . The temperature profile was decided by different equations of boundary conditions instead of linear changes reported in some literature. , The effect of slag physical properties on the slag behaviors was investigated in our previous studies. , The slag contains bubbles, and the slag behaviors were influenced by the gas volume fraction of bubbles. The solid–liquid slag layer interface was determined, and the results showed error while using T cv as the solid–liquid interface temperature for the glassy slag.…”

Section: Introductionmentioning

confidence: 99%

Modeling Study of the Slag Behaviors and SiC Refractory Wall Corrosion on the Top Cone of a Membrane Wall Entrained-Flow Gasifier

2020

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Slag behaviors on the top cone are significant characteristics that relate to the refractory wall corrosion and safe operation in a membrane wall gasifier. The slag flow and heat transfer model was established to predict the slag behaviors on the top cone of a gasifier. The results showed that the closer to the top outlet of the gasification chamber, the thinner the slag thickness, the higher the slag layer heat flux density and refractory wall surface temperature. The mean slag thickness of the top cone was thinner and the mean heat flux density of the top cone was higher than that of the bottom cone, thus the protection of the upper refractory wall was weakened. Especially, the heat transfer rate of the overall top cone significantly decreased when the cone angle increased. Moreover, the refractory wall corrosion model was built based on the active oxidation behavior. The results showed that the refractory wall surface temperature and linear corrosion rate significantly increased, while the gas temperature increased.

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“…It is well-known that the temperature distribution significantly affects the thickness and flow characteristics of the slag, which is crucial to the safe operation of the gasifier. 8 − 11 Therefore, it is necessary to study the effect of the bias angles of the four burners installed in the first stage on the gasifier performance. During the actual process, more detailed information cannot be achieved because of the high operating pressure and temperature easily causing the explosion and leakage of the combustible gas when opening holes on the wall.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on the Effect of Burner Bias Angles on the Performance of a Two-Stage Entrained-Flow Gasifier

Wang

et al. 2022

ACS Omega

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A 2000 t/day HNCERI (Huaneng Clean Energy Research Institute) entrained-flow pulverized coal gasifier suffers from the problem of a high ash–slag ratio. An appropriate bias angle of the burners is the key to solve this issue for the gasifier with a specific structure. A random pore model considering bulk and pore diffusion effects was extended by user-defined function to describe the gasification reactions. The simulation of the gas flow and char gasification characteristics under different bias angles (0, 1.5, 2.5, 3.5, and 4.5°) of the four burners in the first stage was conducted. The simulation results showed favorable agreement with the industrial data. The evaporation, devolatilization, and char oxidation mainly occurred in the first-stage jet zone, and the upflow and downflow zones are dominated by the gasification reactions. The bias angles of the burners mainly affect the scale of gasification reaction zones. As the bias angles increased from 0 to 4.5°, the gas temperature at the slag tap hole decreased from 1880 to 1500 K. The carbon conversion efficiency of the first stage decreases and that of the second stage increases with the bias angle increasing. An optimal bias angle of 2.5° is recommended for the HNCERI gasifier with a total carbon conversion efficiency of 98.16%.

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Effects of the bubbles in slag on slag flow and heat transfer in the membrane wall entrained-flow gasifier

Cited by 20 publications

References 29 publications

Modeling Study of the Slag Behaviors Based on Temperature–Time–Viscosity of Crystalline Slag in an Entrained-Flow Gasifier

Modeling Study of the Slag Behaviors Based on Temperature–Time–Viscosity of Crystalline Slag in an Entrained-Flow Gasifier

Modeling Study of the Slag Behaviors and SiC Refractory Wall Corrosion on the Top Cone of a Membrane Wall Entrained-Flow Gasifier

Numerical Simulation on the Effect of Burner Bias Angles on the Performance of a Two-Stage Entrained-Flow Gasifier

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