Case Number 095021 - Heat-Exchanger/Wet-Film Electrostatic Precipitator for Flue Gas Cleaning
Contact: Geoffrey Pinski
Description: This process involves two sections of electrostatic precipitator (ESP): the collection plates of
the first section act as heat exchanger plates where simultaneous cooling and particle collection are
taking place, and the collection plates of the second section are covered with wet film of water
flowing downward where simultaneous condensation and collection of acid neutralization products
are taking place.
The purpose of the first section is to simultaneously remove particles (mostly flyash) and
recover heat, and yet to maintain a dry condition preventing corrosion in the system. The temperature
of the first section is maintained at between 5 and 300F above saturation. To prevent collection
of sulfur trioxide and other acidic compounds on the collection plate, a small amount of calcium
hydroxide or equivalent caustic material(s) (e.g., ammonia gas) up to a 10% of acid molar amount is
injected upstream of the first section. It is expected to achieve almost a complete removal of flyash
and solid particles at this section.
An equimolar amount of gaseous ammonia and/or fine powders of other alkaline materials is
injected between the first and second sections. The alkaline compounds quickly react with sulfur
dioxide, sulfur trioxide and various forms of nitric oxides, and the reaction products in the form of
fine particles are electrostatically charged by high voltage wires and effectively collected by the wet
collection plates of the second section. The collected reaction products on the collection plates are
carried down and dissolved by the water flowing down from the top of the plates. Up to a 98%
removal of acidic gas components is expected. The bottom pool of product solution is pumped out
for further treatment and water recycling.
The advantages of this invention over the established art are as follows:
- Low gas-phase pressure drop.
- Low liquid pumping cost.
- High removal efficiency of sulfur oxides and nitric oxides.
- High removal efficiency of particles.
- Heat recovery.
- Water recovery from flue gas.
US Patent # 7,022,296 - Method for treating flue gas, issued on April 4, 2006