Thickened sludge is pumped into a dewatering centrifuge which spins at 2,600 rpm to increase solids concentration from 5% to 28% to a consistency similar to moist soil.
Dewatered “cake” falls into a cake bin. A sliding frame and an extraction screw conveyor feeds cake into the cake pump.
A hydraulically powered piston pump feeds cake through pipes to the fluidized bed incinerator.
Emulsion or mannich polymers make the thickened sludge particles adhere to each other assisting in the dewatering process in the centrifuges.
The cake combusts at a temperature of 1,375 degrees Fahrenheit in a bubbling sand bed. Combustion reduces the volume of cake by 95% and eliminates bacteria. The cake has enough energy that the incinerator normally burns cake without the need for supplemental natural has fuel.
Hot flue gas leaving the incinerator is recovered to preheat the fluidizing air entering the bottom of the incinerator.
The waste heat boiler recovers heat from the flue gas by converting water pumped through hundreds of metal tubes into steam.
Powdered activated carbon is injected into the flue gas to remove mercury.
Carbon is injected into the flue gas to remove mercury.
The baghouse uses 816 filter bags to remove particulates which include injected carbon and heavy metals. The particles collected on the outside of the bags fall to bottom in the form of ash.
Water is sprayed into the wet scrubber to cool the flue gas and remove remaining particulates. Caustic is added to neutralize acid gases.
The wet electrostatic precipitator uses electrically charged metal rods to remove any remaining very fine particulates and heavy metals from the flue gas.
Emissions leaving the stacks are clean, odorless, colorless, and have no visible plume.
The fluidizing air blower pushes air through the primary heat exchanger and 1,300 tuyeres to fluidize the sand inside the incinerator.
The induced draft fan pulls the flue gas from the incinerator, energy recovery, and air pollution control systems and pushes the clean flue gas through the secondary heat exchanger and out the stack.
Ash transporters under the baghouse and waste heat boiler collect ash and use compressed air to push ash to storage silos.