SWAG agenda 042215 - Laserfiche WebLink

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93 Comprehensive Review of Solid Waste Collection and Disposal Options incoming waste so that materials with different moisture contents are gradually intermixed to try to get uniform moisture content. Exhibit 12 -1. Cross - Section of Typical Mass -Fired Waterwall Facility TIPPING AREA TURBINE GENERATOR STEAM TO CUSTOMER STEAM TO G BOILER AIR POLLUTION ,/� CONTROL EQUIPMENT CRANE --► ,.t,. rti-c _ HOPPER .N, • a ~� �. - ' �: REFUSE PIT FEEDER BOILER ASH STACK The refuse is then discharged into refuse feed hoppers, which meter out the refuse into the combustion chamber, either by gravity feeding or by a hydraulic feeding device. In a majority of systems, the waste is then pushed onto an inclined, step - like, mechanical grate system which continuously rocks, tumbles, and agitates the refuse bed by forcing burning refuse underneath newly fed refuse. Generally, most systems have three zones of activity along the grates: drying, ignition, and burnout. Holes in each grate bar allow underfire air to pass through the grates resulting in cooling and, thus, preventing thermal damage to the grate system. The width of the grate and the number of grate steps is dependent not only upon the manufacturer's specifications, but also on the overall size of the WTE system. There are five basic moving grate designs: • Reciprocating Grate. This grate resembles stairs with alternating fixed or moving grate sections. The pushing action may be in the direction of waste flow or in an upward motion against the waste flow. • Rocking Grate. Pivoted or rocked grate sections produce an upward or forward motion, advancing the waste down the grate. • Roller Grate. A series of rotating stepped drums or rollers agitate the waste and move it down the grate. • Circular Grate. A rotating annular hearth or cone agitates the waste. v2.1 159 10/22%12