The electrostatic precipitator（ESP） upgrading is highly demanded for ultra-low emission from coal-fired flue gas. The particle emission can only be controlled by increasing ESP length or height under the guide of revised Deutsch Equation

traditionally. However

by adopting ESP index

the product of average

peak electrical strength

and specific collection area

particle emission can also be reduced by increasing operating voltage and current. The final dust emission can be limited under 10 mg/m3 by a series of upgrading steps: replacement of single-phase power source by three-phase power source

flue gas cooling under 110 ℃

mixed rapping with side-rapping for front-side fields and top-rapping for end-side fields

integration of desulfurization devices and ESPs

etc. Besides

replacement of fabric filter by ESP can prevent the clogging of filters and limit the visible near-stack plumes and acid aerosol mists while reducing particle emission.