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To investigate sulfur transformation during coal pyrolysis with char heat carrier (CHC), the effects of temperature, CHC/coal, and CHC production temperature were explored in a fluidized bed. The yield rates of sulfur in H2S (YH2S) and YCOS elevated with temperature. YCH3SH and Ychar‐S decreased, and temperature showed no significant effect on Ytar‐S. CHC inhibited sulfur transformation to the gas phase. More H2S and COS were fixed in mixed‐char in form of CaS by CHC, resulting in the increase of Ychar‐S. CHC was favorable for CH3SH decomposition. The inhibitory effect was enhanced with increasing CHC/coal. Higher production temperature inhibited the sulfur fixation capacity of CHC. CHC enhanced the decomposition of pyrite, organic sulfur, sulfate, and the yield of sulfide in mixed‐char. [ABSTRACT FROM AUTHOR]

An integrated model was developed to investigate the effect of temperature on the particle re-entrainment in a high-temperature electrostatic precipitator (ESP). The numerical model considered the electric field, flow field, particle migration, and particle re-suspension due to the rupture of static equilibrium. The electric and flow field distributions at different temperatures were investigated. The minimum critical shear velocity needed to detach high-temperature deposited particles from the plate surface was calculated and discussed. On these basis, five types of ESPs with collection plates of different configurations were compared. The results show that high temperatures will exacerbate particle re-entrainment caused by airflow scouring and electrostatic lifting by enhancing the ionic wind and reducing particle resistivity. The hole-type plate may be a better plate form to reduce re-entrainment in the high-temperature ESPs, as it creates a low velocity, low electric field region in the near-plate region. [Display omitted] • A modified high-temperature ESP model involving particle re-entrainment was developed • The effect of temperature on the electric and flow field was investigated numerically. • The effect of temperature on the particle re-entrainment was evaluated. • The effectiveness of different types of collection electrodes in reducing particle re-entrainment was evaluated. [ABSTRACT FROM AUTHOR]

• A modified ESP model suitable for high temperature gas was established. • The effect of temperature on ESP performance was investigated numerically. • An optimized ESP with assistant electrodes was developed and compared with the conventional ESP. High-temperature electrostatic precipitators (ESPs) are a potentially effective technology for purifying high-temperature gases. In this study, a comprehensive numerical model was developed to investigate the electric field and particle migration characteristics of an ESP at temperatures ranging from 400 to 600 °C. Moreover, an optimized ESP with assistant electrodes for improved high-temperature particle capture was proposed. The electric field, flow field and particle capture characteristics of the two types of ESPs were compared to demonstrate the superiority of the optimized ESP. Results indicated that high temperatures had a negative impact on ESP performance. As the temperature increased, the operating voltage of the ESP decreased, leading to decreases in both the electric field strength and space charge density. The effective migration velocity of the particles also decreased with increasing temperature, and the inhibitory effect of high temperature on particle capture increased with increasing particle size. The optimized ESP with assistant electrodes exhibited more favorable electric field and flow field characteristics for particle capture compared to those of the conventional ESP. The optimized ESP exhibited higher electric field strength, which increased the electric field force on the particles and promoted particle capture. Meanwhile, the space charge density of the optimized ESP was lower, effectively inhibiting the occurrence of back corona. Moreover, the optimized ESP enhanced the ionic wind downstream of the discharge electrode, thereby promoting particle migration towards the collection electrode. Consequently, the ESP with assistant electrodes effectively improved the collection efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • The transformation paths of sulfur during coal steam gasification with CaO addition was identified. • The release characteristics of H 2 S were monitored online. • Factors which might affect the sulfur transformation were analyzed in detail. To investigate the effects of temperature, Ca-based absorbent (CaO) and atmosphere on the sulfur transformation characteristics in coal steam gasification, experiments were conducted in a fixed-bed reactor. As temperature increased from 600 °C to 750 °C, H 2 S-S (sulfur in H 2 S) was elevated by 21.86% and absorbent-S decreased by 7.66%. More gaseous sulfur was captured by organic groups to form organic sulfur in char at higher temperature. CaO promoted the sulfur conversion, and played the role of gaseous sulfur absorbent at the same time, and showed an ability of organic sulfur removal. CaO slowed down the H 2 S release by reacting with it to form CaS, resulting in that the peak concentration of H 2 S without CaO reached 1026.7 ppm, which decreased to 426.3 ppm with CaO. The increase in Ca/C promoted the sulfur conversion slightly and reduced the sulfate content in char. Compared with inert atmosphere, H 2 S-S in the steam atmosphere increased by 35.07%, while absorbent-S decreased by 23.42%. The solid–solid reaction mechanism is more suitable for the sulfate transformation in inert atmosphere, while the gas–solid reaction mechanism is more suitable in steam atmosphere. The sulfur conversion in inert atmosphere was lower, but sulfate had a higher decomposition rate. [ABSTRACT FROM AUTHOR]

In this study, a numerical model of an electrostatic precipitator (ESP) suitable for high-temperature flue gas was established using COMSOL Multiphysics, and the effects of temperature and H 2 O concentration on the high-temperature ESP performance were studied. The results showed that, at the same voltage, increasing the temperature increased the negative ion density, thereby improving the particle charge and collection efficiency. However, increasing the temperature led to a decrease in the maximum operating voltage of the ESP, which reduced the negative ion density and electric field intensity at the maximum operating voltage and weakened the diffusion and field charges of the particles, leading to a further decrease in the maximum collection efficiency. Increasing the H 2 O concentration in the flue gas increased the negative ion density and, thus, enhanced the diffusion charge of the particles, which helped improve the collection efficiency. [Display omitted] • A modified ESP model suitable for high temperature gas was established. • The plasma model was used to simulate corona discharges in the ESP. • The effect of temperature on ESP performance was studied numerically. • The effect of H 2 O concentration in flue gas on ESP performance was studied. [ABSTRACT FROM AUTHOR]