Development of Continuous Steelmaking Slag Solidification Process Suitable for Sensible Heat Recovery

Tobo, Hiroyuki; Ta, Yasutaka; Kuwayama, Michihiro; Hagio, Yuki; Yabuta, Kazuya; Tozawa, Hirokazu; Tanaka, Toshihiro; Morita, Kazuki; Matsuura, Hiroyuki; Tsukihashi, Fumitaka

doi:10.2355/isijinternational.55.894

Cited by 16 publications

(19 citation statements)

References 13 publications

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“…Therefore, simple modeling by separating the "near-wall region" having porosity of εw and "central region" having porosity of εc in the porous medium was adopted to simplify the model [25]. The thickness of the near-wall region (X in Figure 6) can be estimated by the following porosity function shown in Equation (6), which is defined within the distance from the column wall [26][27][28]. The parameter A decides the porosity increment in the vicinity of the wall, which is usually decided empirically.…”

Section: Laboratory-scale Cfd Simulationmentioning

confidence: 99%

“…Solidifying the slag in a plate-like shape reduces the heat transfer distance in the slag thickness direction, which has the effect of reducing the decrease in heat recovery caused by the slower heat conduction inside the slag. Tobo et al [6] investigated the optimum operating conditions of a twin-roll continuous slag solidification plant (hereafter 'twin-roll plant') for production of plateshaped slag with the average thickness about 7 mm. With this thickness of the slag, the Biot number of the slag during heat recovery at the slag charging temperature of 1373 K is estimated to be about 0.02, which is small enough to neglect the effect of the heat conduction inside the slag plate.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Gas Velocity Distribution on Heat Recovery Process in Packed Bed of Plate-Shaped Slag

Shigaki¹,

Ozawa²,

Sumi³

2017

Energies

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Abstract:A new twin-roll continuous slag solidification process and heat recovery process from a slag packed bed was developed for utilization of the waste heat of steelmaking slag. Plate-shaped slag with the thickness about 7 mm was successfully produced in a pilot plant, and the sensible heat of the slag was recovered by blowing air into the slag chamber. However, the gas distribution inside the slag packed bed was unclear because of the unique shape of the slag plates, and this remained a concern for further scale-up designing of the slag chamber. Therefore, in order to estimate the gas distribution in the packed bed, a simple computational fluid dynamics (CFD) model which considers the wall effect around the inner wall of the chamber was developed, and this model was fitted to the results of laboratory-scale velocity distribution measurements. The results showed that the gas velocity distribution was properly estimated, and the intensity of the wall effect was similar in both cases. As the next step, the gas velocity distribution and its effect on the slag heat recovery process in a pilot-scale slag chamber were evaluated with the assistance of the CFD simulation model. The simulation results were compared with the measured data obtained in a pilot-scale test, and as the result, a similar wall effect was also observed in the pilot-scale chamber. However, the intensity of the wall effect was limited enough to prevent serious deterioration of the uniformity of the gas distribution.

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Section: Laboratory-scale Cfd Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Gas Velocity Distribution on Heat Recovery Process in Packed Bed of Plate-Shaped Slag

Shigaki¹,

Ozawa²,

Sumi³

2017

Energies

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“…Entretanto, a maioria desses processos não teve sucesso em escala industrial devido à instabilidade das propriedades físicas da escória como a viscosidade, que muda drasticamente dependendo da temperatura e composição química da escória (8). Outros processos de granulação e o uso de um leito fluidizado foram examinados, mas como o produto desses métodos consiste em partículas esféricas pequenas, seu uso era limitado (6).…”

Section: Escóriaunclassified

“…em dois rolos para solidificação da escória e um trocador de calor contracorrente de leito fixo (Figura 3).Escória líquida é despejada nos rolos, que giram em direções opostas, onde se solidifica e então é levada pela correia transportadora até o trocador de calor(6). Os rolos são feitos de cobre e giram para cima em direções opostas em contato.…”

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“…A escória é abastecida em fluxo constante e é solidificada na superfície dos rolos, caindo no transportador após meia volta devido ao seu próprio peso. Os rolos também são munidos de um sistema de arrefecimento, geralmente a água, para também aumentar a capacidade de resfriamento da escória(6).Com a planta, não há a necessidade de um grande local para o resfriamento da sucata, além disso é obtida uma escória de espessura pequena (entre 5 e 20mm) o que facilita seu processamento, reduzindo a geração de pó durante o processo de Planta de recuperação de calor(8) granulação (Figura 4). Também se torna desnecessária o arrefecimento a água e consequentemente um processo de secagem posterior.…”

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Análise De Uma Planta De Recuperação De Calor Da Escória Através Da Modelagem De Um Trocador De Calor Contracorrente De Leito Fixo

BARBOSA¹

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Analysis of a slag heat recovery plant by modeling a fixed bed countercurrent heat exchangerSteel is a basic input for the industrial sector of any country. Steel production faces many challenges today, two of which are CO2 emissions and waste generation. In 2017 alone, the absolute emission of CO2 was 65,397 tons. In the same year, the amount of solid waste generated reached the average index of 607 kg per ton of steel, of which 70% were slag (Blast Furnace and Meltshop). The waste of these wastes translates into an economic and environmental problem. The reuse of these wastes faces some challenges, one of them being the slag cooling. Today, slag cooling is done outdoors in most plants, takes up a lot of space and depends on factors such as ambient temperature besides wasting energy to the environment in the form of heat. Projects around the world have been created to address these issues, such as CORSE 50 in Japan and RESLAG in Europe have sought to utilize the sensible heat recovered from slag in CO2 separation, thereby helping to reduce CO2 emissions. It also deals with the problems involving the slag that were mentioned. The objective of this work is to model a fixed bed countercurrent heat exchanger, like the one used in the CORSE 50 project using a one-dimensional (1D) steady state approach, using the Runge-Kutta method, to analyze the amount of energy recovered, the temperature profiles and to compare the modeling results with the experimental data of the project. For this, a routine was developed in MatLab with two possibilities: constant slag and air thermophysical properties, and slag and air thermophysical properties varying with temperature. The equation used to describe temperature was very sensitive to boundary conditions, which resulted in non-convergence of the MatLab model.

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Integrated Heat Recovery and Material Recycling from Hot Slags: Toward Energy Saving and Emission Reduction

Sun

Zhang

2016

Advances in Molten Slags, Fluxes, and Salts

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Development of Continuous Steelmaking Slag Solidification Process Suitable for Sensible Heat Recovery

Cited by 16 publications

References 13 publications

Effect of Gas Velocity Distribution on Heat Recovery Process in Packed Bed of Plate-Shaped Slag

Effect of Gas Velocity Distribution on Heat Recovery Process in Packed Bed of Plate-Shaped Slag

Análise De Uma Planta De Recuperação De Calor Da Escória Através Da Modelagem De Um Trocador De Calor Contracorrente De Leito Fixo

Integrated Heat Recovery and Material Recycling from Hot Slags: Toward Energy Saving and Emission Reduction

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