Specific emission control processes
EP Absorber
Customized Gas Cleaning Systems for Fluid Catalytic Cracking (FCC) units. Clean air solutions that keep the CAPEX / OPEX low using Electrostatic Precipitation.
One of GEA´s most important emission control activities in the refinery industry is the gas cleaning for FCC units and for this purpose builds Electrostatic Precipitator Absorber (EP Absorber).
Electrostatic Precipitators and wet gas scrubbers are widely used to remove contaminants such as sulfuric acid mist and particulates from the FCC flue gas.
EP Absorbers solve several limitations on SOx control and are typically located downstream the FCC units, before the flue gas is exiting to atmosphere through the stack.
The EP Absorber combines two processes: The absorption and the electrostatic precipitation.
The flue gas enters first the wet scrubber where the cooling of the gas and the SO2 absorption take place and second the electrostatic precipitator whereby electrostatic forces, particulate matter and SO3 mist of submicron-diameter are removed from the process gas.
The EP Absorber can be designed for inlet gas temperatures up to 600°C.
The advantage of the EP Absorber is the compact arrangement of three elements: wet scrubber (absorber), wet electrostatic precipitator and stack.
Particular features of the EP Absorber:
- Lower emissions compared to conventional SO2 Scrubbers
- Less energy consumption due to low pressure drop, hence no additional booster fan needed
- No boiler reinforcements for increased operating pressure needed
- No brownish trailing SO3 plume
- Scrubber nozzle maintenance and replacement during operation
- Heavy duty discharge electrodes for long run times
- Redundant high-quality T/R Sets and controllers
Working Principle
Working Principle of EP Absorber
EP Absorber designs are of the vertical type with the gas inlet either at the top or at the bottom and gas distribution devices are installed ahead the electrical fiel. It can either flow up or down relative to where polluted air enters the Absorber during the particulates control process. Turing canes and a perforated plate evenly distribute the gas glow inside of the ESP Absorber.
The flue gas enters first the wet scrubber environment ensuring that the sulfuric acid is condensed and collectable by electrostatic forces.
In the case of a precipitator design with single tubes, these are suspended from an upper tube plate and selaed by means of o-rings. The lower tube ends are fitted into a grid allowing unrestricted expansion.
In the case of two precipitators in series, the gas normally passes through the first stage from bottom to the top, in the second stage from top to bottom. The off-gas is routed though the precipitator tubes with disccharge electrodes suspended down each vertical axis. Ba applying high voltage, an electric field will be produced which will electrically charge the aerosol and dust particles that, in turn, migrate to the collection tubes.
All parts coming in contact with the gas are either lead coated, plastic or rubber lined. The materials are selected in order to accommodate the stresses and temperatures to which the plant is subjected.
The collecting surface is formed by round tubes to a length of maximum 6m. Material options are either Polypropylene (PP) or Polyvinylchloride (PVC). The surface of both materials is given a special treatment that permits the formation of a continuous liquid film on the surface.
Its design has a unique alignment mechanism to hold electrodes rigidly in place reducing installation and maintenance time while keeping the performance up. The field strength is consistenly maintained at high levels with minimal sparking, resultin gin the highest available efficiency.
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