System And Process For Removing Particulate From A Coal Fired Power Waste Stream

Abstract

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.

We claim: 
     
         1 . A closed loop system for removing particulate from a coal fired power waste stream comprising:
 a) at least one boiler, including wash water inlets;   b) at least one submerged flight conveyor, including a horizontal section for receiving wash water and an incline dewatering section adjacent to the horizontal section;   c) a bleed line 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 and an inclined section;   b) a plurality of scrapers rotating through at least the horizontal section;   c) a bleed line 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 coal fired power 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 coal fired power waste stream is pretreated with at least one of a pH adjustment, coagulant and flocculent to precipitate dissolved metal therefrom. 
     
     
         6 . A method for treated a wash water waste stream from a coal fired boiler 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 night 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 night 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 create the wash water waste stream in a coal fire boiler;   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.