Falling film evaporation of desulfurization wastewater with synergistic particle removal based on the dry-wet coupling electrostatic precipitator

Abstract

Low temperature flue gas evaporation is an effective method for low-cost and efficient treatment of desulfurization wastewater (DW). However, due to the influence of low flue gas temperature and high salt content, it is easy to lead to scaling and blockage of evaporation flue, affect the stable operation of the system. In order to effectively use the waste heat of flue gas to treat DW and avoid the corrosion of DW to the flue, the falling film evaporation treatment technology of DW with synergistic particle removal is proposed. The effects of different operating parameters on the falling film evaporation and deposition characteristics of DW, and particle removal efficiency are studied. The results show that the increase of the electrostatic field voltage is conducive to the evaporation of DW, and inhibits its crystal deposition. The increase of the Cl- concentration is inconducive to the evaporation and crystal deposition of DW without electrostatic field, but is conducive to the evaporation and crystal deposition of DW in the electrostatic field. In the experiment of 120 ℃ flue gas, the evaporation capacity of liquid film decreases by 17.9% with Cl- concentration increasing from 0% to 5% without the voltage; but the evaporation capacity of liquid film increases by 30.9% with Cl- concentration increasing from 0% to 5% after applying 40 kV voltage. Replacing water with DW is conducive to the removal of particles by electrostatic field. The efficiency of particle removal increases from 79.9% to 84.8% with Cl- concentration increasing from 0% to 5% at 120 ℃ and 40 kV. In addition, increase on flue gas temperature is also conducive to the DW evaporation and particles removal by electrostatic field. Compared with other wastewater treatment technologies, this technology has the advantage of low treatment cost.