DESIGN ASPECTS AND PERFORMANCE TESTING OF A ROTARY KILN TRASH INCINERATOR WITH A FLUE GAS CONDITIONING TRAIN CONSISTING OF A BOILER, FABRIC FILTER, DRY LIME INJECTION SYSTEM, AND CARBON INJECTION SYSTEM

摘要

Hankin Environmental Systems Inc. (Hankin) recently completed the commissioning, start up, and performancerntesting of a rotary kiln trash incineration system. The rotary kiln incinerator was installed in Beijing, Chinarn(PROC) as part of the terminal expansion project at the Beijing Capital International Airport. The feed to the rotaryrnkiln incineration system consists of refuse from the arriving airplanes and terminal waste collectors. The primaryrncomponents in the feed are plastic bags, plastic utensils, plastic cups, paper bags, magazines, newspapers, foodrnscraps, cans, bottles, etc. The metallic and glass items are manually removed from the feed before entering thernrotary kiln incineration chamber.rnThe rotary kiln Incineration system is primarily comprised of an inclined cleated belt conveyor, rotary kilnrnincineration chamber, secondary combustion chamber or afterburner, 3 pass fire tube waste heat boiler, steam recirculationrnloop, fabric particulate filter, dry hydrated lime injection system, dry activated carbon injection system,rnand an induced draft fan.rnThe rotary kiln incineration system incorporated multiple design aspects to increase efficiency and performance.rnOne primary design aspect was a fuel efficient process needing minimal auxiliary fuel to sustain combustion.rnDuring the performance test the fuel consumption was a nominal 219 liters per hour. The second primaryrndesign aspect was to increase the refuse retention time in the rotary kiln chamber by adding protruding refractoryrnanchors in the first third of the chamber. Retention time was increased by five (5) minutes beyond the theoreticalrncalculated retention time. The protruding refractory anchors also increased agitation to the refuse allowing more ofrnthe refuse surface area to be exposed to the oxidizing atmosphere. The result was an ash with a combustible matterrncontent ranging from 3.0%-4.3% by weight. The third design aspect was to conserve make-up water usage by thernoverall system. This design incorporated a steam re-circulation loop that condenses steam produced by the boilerrnand re-circulated it back to be used as make up water for the boiler. This condensate is used as boiler feed waterrnwhen steam is not required to heat airport buildings. Less than one (1) liter of water was consumed over the performancerntest period. Steam was re-circulated over the entire performance test period.rnVery high overall collection efficiencies were observed for five (5) heavy metals, cadmium (Cd), chromiumrn(Cr), mercury (Hg), manganese (Mn), and lead (Pb). The theoretical collection efficiencies for the five (5) heavyrnmetals were 99.91%, 99.99%, 74.72%, 99.97%, 99.99% respectively. Activated carbon injection and a fabric particulaternfilter, were used to achieve the high heavy metal collection efficiencies. Hydrated lime was injected priorrnto the fabric particulate filter for acid gas absorption and neutralization. The primary acid gases, SO_2 and HCL,rnwere reduced by 94.90% and 99.89% respectively. Particulate removal efficiency over the entire process was inrnexcess of 99.92%. CO and NO_x emission concentrations were a nominal 14 mg/Nm~3 and 91.5 mg/Nm~3 respectively.rnStack Opacity was less than one (1) Rigleman.