ALCOSAN Waste Water Treatment
Plant (WWTP)
193 DTPD (Sewage Sludge)
52,800 pph steam, 450 psi, 460 deg. F
| Owner Allegheny County Sanitary Authority (ALCOSAN) Project Location Project Completion |
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Project Description
This state-of-the-art facility features two EPI fluid bed energy systems that convert all
of the residues from the ALCOSAN Waste Water Treatment Plant into usable energy. Each
system produces 26,400 pph of steam for process use and electrical power generation within
the treatment facility. Each fluid bed system has a design capacity of 78.8 Dry Tons Per
Day (DTPD) primary and secondary sludge at 20% solids, 12.6 DTPD grit at 70% solids, and 5
DTPD scum and grease at 50% solids.
Fluidizing air is preheated to 400o F through a flue-gas-to-air preheater and a steam to air preheater before entering the combustion process. The preheated air allows self-sustaining combustion without the addition of auxiliary fuel.
Flue gases leave the fluid bed combustion cell at about 1550o F and pass through an afterburner, where odorous gases, collected from throughout the plant, are burned. The flue gases leaving the afterburner pass through a forced circulation boiler, where about 26,400 pph steam at 450 psig and 460o F are produced. They then pass through a high efficiency multiple cyclone dry collector, an economizer and the air preheater. Final particulate removal consists of a high energy variable throat venturi scrubber, followed by a three tray impingement scrubber to remove acid gases. The tray scrubber is equipped with a two stage chevron and mesh mist eliminator. The ID fan, located after the scrubber, delivers the cleared flue gases to the stack.
A unique feature of this project is the requirement for a proven inert removal and bed material reinjection system. EPI's patented tramp removal system automatically removes contaminated bed material from the vessel, screens the material to remove the grit and returns the cleaned bed material to the combustor while the system remains in full operation.
Scope of Supply
EPI designed, manufactured and installed the two fluid bed combustion units, complete with
inert removal systems, preheat burners, after burners and all interconnecting flue gas
ducting. EPI also designed and manufactured the air preheaters, installed the steam heated
sludge dryers and supplied the flue gas scrubbing systems. Start up support and operator
training assistance was also provided.