Low low temperature ESP is to lower ESP inlet gas temperature below acid dew point by low temperature economizer or hot media gas gas heat exchanger (MGGH), normally gas temperature is below 90℃, so that most of SO3 in the gas will condense into sulfuric acid mist in the low temperature economizer or MGGH, stick on the dust and be neutralized by alkaline substance, that greatly reduce dust resistivity and avoid back-corona, improve collecting efficiency and remove most of SO3, save energy when use low temperature economizer.

　　Features:
　　1. high collecting efficiency     
　　(1) low resistivity.  Low low ESP lower gas temperature below acid dew point, gas temperature is so low and especially with condensation of SO3 that dust resistivity is greatly reduced, that can avoid back-corona and improve collecting efficiency( indicated as picture 4).Under this mode, it can meet emission standard without dust collecting tower and wet scrubber. Outlet dust loading of low low ESP is less than 30mg/Nm3, and guarantee that outlet dust loading is less than 10mg/Nm3 by installing wet process FGD system.
　　(2）breakdown voltage increase. Decreasing of Flue gas temperature make breakdown voltage increase, so that collecting efficiency is improved.
　　(3) gas volume decrease. Gas volume decrease correspondingly due to flue gas temperature decrease, velocity within electric field of ESP drops and specific collecting area increase, that facilitate dust collection.
　　2. Most of SO3 are removed
　　When ESP flue gas temperature is below acid dew point, gaseous SO3 will change into liquid sulfuric acid mist. High dust concentration result in large total surface area, and that provide good condition for condensation and sticking of sulfuric acid mist. When rate of dust concentration (mg/Nm3) to sulfuric acid mist concentration(mg/Nm3) is above 100, SO3 removal efficiency can be over 95% and SO3 concentration is lower than 1ppm(approx. 3.57mg/Nm3)
　　3. Save energy much when using low temperature economizer
　　Through calculation and analysis for saving energy of low low ESP for 1 set of 1000MW unit, in case 30℃ of gas temperature is lowered, it can reclaim 1.64×108kJ/h heat, save 70t/h water for wet process FGD, meanwhile, after gas temperature lowered, actual gas volume reduce greatly, not only this can minimize size of downstream equipment, and also reduce 10% power consumption of ID fan, power supply of FGD system is reduced from 1.3% to 1.0%.

　　Typical system flow chart