System and process for removing particulate from a coal fired power waste stream
A system and process for closed loop system for removing particulate from a coal fired power wash water waste stream comprising a submerged flight conveyor for receiving used wash water, a bleed line for diverting wash water from the submerged flight conveyor, a filter for removing particulate from the diverter wash water, and pumps to recirculate the wash water on a loop through the system.
1. A closed loop system for removing particulate from a coal fired power waste stream comprising:
a) at least one hopper, including wash water inlets;
b) at least one submerged flight conveyor, including a horizontal section for receiving wash water, the horizontal section including a series of lamella plates so as to capture particulate therefrom, and an incline dewatering section adjacent to the horizontal section;
c) a bleed line below the series of lamella plates for draining wash water from the submerged flight conveyor adjacent the joint between the horizontal and incline sections;
d) a filter connected to the bleed line for removing particulate from the wash water; and
e) a return pump for feeding the filtered wash water to the wash water inlets.
2. A system for processing particulate from a wash stream in a coal fired power waste stream comprising:
a) a submerged flight conveyor including substantially horizontal section including a series of lamella plates so as to capture particulate therefrom, and an inclined section;
b) a plurality of scrapers rotating through at least the horizontal section;
c) a bleed line below the series of lamella plates proximate the joint between the horizontal and incline sections; and
d) a filter connected to the bleed line for removing particulate from the coal fired power waste stream.
3. The closed loop system of claim 2 wherein the filter is a bag filter.
4. The closed loop system of claim 2 wherein at least a portion of the waste stream is dewatering by the incline section of the submerged flight conveyor.
5. The closed loop system of claim 2 wherein at least a portion of the waste stream is pretreated with at least one of a pH adjustment, coagulant and flocculent to precipitate dissolved metal therefrom.
6. A method for treating a wash water waste stream from a hopper comprising:
a) receiving the wash water waste stream into a submerged flight conveyor, the submerged flight conveyor comprising substantially horizontal and inclined portions;
b) treating a first portion of the wash water waste stream with a series of lamella plates so as to capture particulate therefrom;
c) removing a second portion of the wash water waste stream from the submerged flight conveyor via a bleed line for processing in a thickening tank and filter to capture particulate therefrom;
d) returning water removed from the second portion of the wash water waste stream in the thickening tank and filter to the submerged flight conveyor;
e) removing an overflow portion of water from the submerged flight conveyor to a surge tank;
f) removing a portion of the water from the surge tank to supply wash water to the wash water waste stream in the hopper;
g) returning the remainder of the water from the surge tank to the submerged flight conveyor; and
h) removing settled particulate from the wash water waste stream via the inclined portion of the submerged flight conveyor.