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The high-temperature electrostatic precipitator (ESP) is a potentially efficient method for hot-gas cleaning in advanced technologies, e.g., the coal-staged conversion poly-generation system and IGCC. This paper investigates the characteristics of the ash layer on the internal surface of the anode pipe of a wire–cylinder ESP at temperatures ranging from 350 °C to 700 °C, including ash deposition forms, growth of ash layer and the effect of ash layer on back corona discharge. There are four typical ash deposition forms: the belt form, the slope with ribs form, the slope form and the slope with a thick bottom edge form. Ash layer thickness generally decreases with increasing height. When T ⩽ 500 °C, ash belts form under low port voltages, and with increasing port voltage, they will overlap each other to form ash ribs. When T ⩾ 500 °C, particles are deposited in the smooth slope form if the port voltage is great enough. When T ⩾ 700 °C, a thick bottom ash edge occurs. Ash deposition forms can vary under different operating conditions. As the operating time increases, the thickness growth rate at a given point decreases, and the ash layer height increases because of the repulsive electrical force between the ash layer and the particles. Back corona discharge always occurs on the thickest portion of the ash layer first. The back corona discharge onset voltage decreases nearly linearly with increasing ash layer thickness, from 19,787 V to 17,197 V as the maximum thickness of the ash layer increases from 0.34 to 2.02 mm when T = 500 °C, U p = 17,200 V and m in = 650 mg/N m 3 . [ABSTRACT FROM AUTHOR]

An experimental-scale electrostatic precipitator (ESP) was built to investigate the characteristics of corona discharge, particle migration, and particle collection at various temperatures ranging from 300 K to 900 K. The variations in particle collection efficiencies and migration velocities with temperature, applied voltage, current density, energy consumption density, particle concentration, and flue gas velocity were obtained. Both onset and spark voltages decreased with an increase in temperature and resulted in a decrease in particle collection efficiency and particle migration velocity. At the same voltage, a large current was generated at high temperature; particle charging was enhanced, and high particle collection efficiencies and particle migration velocities were obtained. At the same current and energy consumption densities, the particle collection efficiencies decreased because of the low electric field intensity. The increase in particle concentration was favorable to particle collection and improved the particle migration velocities. The increase in flue gas velocity reduced the particle collection efficiencies and had minimal influence on the particle migration velocities. [ABSTRACT FROM AUTHOR]