Simulation analysis of gas–solid flow characteristics and water evaporation in flue gas semi‐dry desulphurization process based on CPFD method

Abstract

The gas–solids flow in an industrial‐scale semi‐dry method desulphurization tower is simulated by the computational particle fluid dynamics (CPFD) approach. Compared with previous studies on desulphurization towers, this study focuses on analyzing particle distribution characteristics such as particle volume fraction, temperature distribution, and residence time. The simulation fully considered the particle–fluid, particle–particle, and particle–wall interactions in the desulphurization tower. Based on these considerations, the effects of flue gas inlet velocity and temperature on the gas–solid distribution characteristics of the desulphurization tower are simulated. An optimization scheme for adjusting the gas–solid flow in the desulphurization tower is proposed. The research results show that the error between the CPFD simulation data and experimental data is small and the changing trend is consistent. The particles in the bed of the desulphurization tower show a typical core–annulus flow. The distribution of gas and particles in the bed has a serious deviation with the increase of the flue gas inlet velocity and temperature. As the axial height of the desulphurization tower increases, the flue gas velocity, temperature, particle concentration, and water vapour distribution in the bed become more uniform. The relatively stable operating conditions for the gas–solid flow in the desulphurization tower is that the flue gas inlet velocity and temperature are 15 m/s and 393 K, respectively. Under these operating conditions, the pressure loss caused by the venturi accounted for 73.6% of the total pressure loss of the desulphurization tower. When the particle radius is between 0–150 μm, the particle size and the flue gas inlet velocity have the greatest influence on the particle residence time. Finally, the distribution of gas and particles before and after the adjustment of the desulphurization tower is compared, which showed that adjusting the bottom structure of the desulphurization tower could optimize the gas–solid flow.

Gas and slurry flow behaviors in a CO2‐mineralization spray tower reactor

“…During the CO 2 ‐mineralization process in MSTRs, the three‐phase flow of gas, liquid, and solid, as well as the chemical reactions, are extremely complex. To simplify the computational difficulty, the assumptions were made as follows: The slurry droplets were simplified as solid spherical particles, and the agglomeration and fragmentation of slurry droplets during motion were not considered 27,28 ; The reaction between CO 2 and Ca(OH) 2 was mainly considered during the mineralization process, while other secondary reactions had negligible effects and could be ignored; The reaction between CO 2 and Ca(OH) 2 occurred in the liquid phase, and the ion reaction was irreversible and completed instantaneously; The wall of the reactor was assumed to be adiabatic, and the heat of reaction and dissolution was neglected 25 ; The CaCO 3 generation and Ca(OH) 2 consumption effects on slurry size were neglected. …”

“…1. The slurry droplets were simplified as solid spherical particles, and the agglomeration and fragmentation of slurry droplets during motion were not considered 27,28 ;…”

“…25 For example, Guo et al 26 employed the multiphase particlein-cell (MP-PIC) method to simulate the wet desulfurization process in a spray tower, and the gas and slurry were considered as a continuous phase and discrete phase, respectively. Liu et al 27,28 simulated the semi-dry desulfurization spray tower using the Euler-Lagrange method, and they attempted to optimize the gassolid distribution by installing baffles to enhance the desulfurization efficiency. In general, the application of CPFD in spray towers with SO 2 absorption process (SO 2 concentration is less than 0.5%) is relatively mature, which can provide a basis for simulating the CO 2 -mineralization spray process.…”

Reduction of Occupational Risks for the Health of Workers and Improvement of Ecological Safety of the Environment During Cleaning of Industrial Emissions of Metallurgical Enterprises

“…Авторами роботи [9] було виконано моделювання потоку газу та твердих речовин у промисловій вежі десульфуризації напівсухим способом за допомогою підходу обчислювальної динаміки частинок рідини. Запропоновано оптимізаційну схему регулювання газотвердого потоку в сіркоочисній башті.…”

“…Запропоновано оптимізаційну схему регулювання газотвердого потоку в сіркоочисній башті. Визначено, що відносно стабільні робочі умови для газотвердого потоку в десульфуризаційній вежі полягають у тому, що швидкість димового газу на вході та температура становлять 15 м/с і 393 K відповідно [9]. Як недолік можна зазначити відсутність комплексного впливу на ступінь видалення діоксиду сірки як температури, швидкості потоку, так і кількісного складу компонентів для фільтрації в достатньо широкому інтервалі варіювання.…”