Flue Gas Denitration Simulation Of A Domestic Waste Incinerator And Its Application In Operation Optimization

Wit h the developme nt of urbanizatio n,urban garbage proble m is increasing serio us ly in C hina.Waste incineratio n technology whic h has advantages of the "reduct ion" and "resource" has gradually become t he ma instream techno logy of garbage disposal.Secondary pollut io n gases were produced ine vitab ly w hen incinerating,and N Ox is one of the main pollut io n gases in waste incineratio n.In order to meet the latest natio nal and local standards and control the NO x emiss ion,denitrat ion transfor matio n for exist ing garbage inc inerator should be done.Select ive non-catalyt ic reduct ion(SN C R)is a popular denitrat ion techno logy for garbage inc inerator flue gas,which has simple trans format ion steps and low operating costs.A 400 t/d waste incinerator w ith grate is researched in this paper.Computat iona l fluid dyna mics(CFD)software is used for proposing t he optimizat ion schemes of garbage incinerator flue gas denitrat ion transfor matio n.Firstly,the gas-phase combust ion process and the SN C R process are both modeled,and the models established are verified by measured va lues,experiments and literature evidence.The n the processes of gas-phase combust ion and SNC R are optimized by numerica l simulat ion.Fina lly,the comprehens ive optimizat ion sche mes of garbage inc inerator flue gas denitrat ion trans format ion are proposed and evaluated.To research the influence of secondary air(SA)injection modes on gas move ment and combust ion reaction,six innovated inject ion modes of SA are designed.The result shows that through the optimizat ion of SA inject ion modes,SA can form var ious ris ing-up spira ls that enable the flue gas to produce vortexes,so that t he residence time o f SA is increased up to 40.62%.Based on t hose,SA injection cond it ions are optimized.The optimizat ion o f SA injectio n condit ions is completed by change the SA inject ion speed,wit h primary air(PA):SA=0.72:0.28.By us ing the established SNC R model,the influe nce of injector parameters(droplet size,injectio n speed,inject ion angle,inject ion mass and inject ion concentration)on evaporation and mixture of reductant in SNC R spraying system are researched,through single factor simulat ion and orthogonal simulat ion.The optimum parameters of nozzle are the droplet size of 400 ?m,the injection speed of 35 m/s,the injection angle of 30°,the injection mass of 50 kg/h,the injection concentrat ion o f 25%.The influence of number and arrange ment o f SNC R nozzles are resea rched using t he optimum parameters,and the optimum arrange ment of SNC R spraying system is spraying t hrough 8 nozzles on 4 walls,w ith 2 no zzles each wall,and the nozzles are uniform distribution.Comb ined wit h the gas-phase combust ion process optimizatio n and SNC R process optimizat ion,the comprehens ive opt imizat ion sche mes wit h high De-NOx rate are designed and screened.Then the project cost and environme ntal economic benefit eva luat ion of comprehens ive optimizat ion sche mes are done.The highest De-NOx rate of schemes reached 55.52%.The lowest garbage denitrat ion cost is 5.46 RMB /t.running to 15 years.N O remova l cost running to15 years of the scheme w ith best enviro nmenta l economic benefit is 5597 RMB / t.The highest NO concentrat ion of t he inc inerat or out let is 183.8 mg/N m3 optimized by upon sche mes.The results meet the GB 18485-2014 standard and the EU 2000 standard,and ammonia leakage vo lume fraction of which are less than 10-4.