2025/6/2218.4Ashdeposit/Corrosion/erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰/磨損和低溫腐蝕1.Ashdeposit尾部受熱面積灰1)積灰及其危害Loose松散性積灰：煙氣攜帶飛灰流經(jīng)受熱面時，部分灰粒沉積在受熱面上形成的。Lowtemperaturecohesive低溫粘結(jié)性：煙氣中的硫酸蒸汽在低溫受熱面上凝結(jié)，將灰粒粘聚形成的。Harm危害:Heattransfercoefficient,heatresistance灰的傳熱系數(shù)很小，使受熱面的熱阻增大，吸熱量減少，排煙溫度升高，排煙熱損失增加，鍋爐效率降低。積灰堵塞部分煙氣通道，使煙氣流動阻力增大，導(dǎo)致引風機電耗增大甚至出力不足，造成鍋爐出力降低或被迫停爐清灰。2025/6/2228.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕1.Ashdeposit尾部受熱面積灰2)Influencefactors積灰影響因素FluegasVelocity煙氣流速：煙氣流速越大，積灰越少（圖10-3）Particlesize飛灰顆粒度：粗灰多，沖刷作用大，積灰少Structureoftubebank管束結(jié)構(gòu)特性：錯列管束積灰輕3)Measurements減輕和防止積灰的措施合理選擇煙速：8~10m/s采用小管徑、小節(jié)距、錯列布置的管束:φ25~32;

s1/d=2~2.5,s2/d=1~1.5布置吹灰裝置，制定合理的吹灰制度W1=2.5～3m/sW3=8~10m/s2025/6/2232.Erosion尾部受熱面磨損Heattransfersurfacesandotherairheaterpartscansuffererosiondamagethroughimpactofhighvelocity,gas-entrainedashparticles.Erosionusuallyoccursneargasinletswherevelocitiesarehighest.圖10-4受熱面管子的飛灰磨損8.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕2025/6/2248.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕2025/6/2258.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕2.Erosion尾部受熱面磨損1)Influencefactors因素Velocity煙氣流速：金屬磨損與煙氣流速的3~3.5次方成正比Concentration飛灰濃度：濃度越大，磨損越嚴重Particlecharacteristics灰粒特性：灰粒粗、硬，磨損嚴重Structure管束結(jié)構(gòu)特性：錯列比順列磨損嚴重2)Measurement減輕磨損的措施合理選擇煙速limitgasinletvelocity：economizer9m/s采用合理的結(jié)構(gòu)和布置:節(jié)距均勻，順列代替錯列加裝防磨裝置coverwithabrasionresistantparts:圖10-6搪瓷涂層和防磨涂料sacrificialmaterials(ceramics):采用膜式省煤器membraneeconomizer：2025/6/2262.Erosion尾部受熱面磨損圖9-30省煤器防磨裝置圖9-31管式空氣預(yù)熱器防磨8.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕2025/6/2278.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕3.Corrosion尾部受熱面低溫腐蝕1)Formationandharm低溫腐蝕及其危害Airheatersusedonunitsfiringsulfurbearingfuelsaresubjecttocoldendcorrosionofheatingelementsandnearbystructures.Inaboiler,aportionofthesulfurdioxide(SO2)producedisconvertedtosulfurtrioxide(SO3)whichcombineswithmoisturetoformsulfuricacidvapor.Thisvaporcondensesonsurfacesattemperaturebelowitsdewpointof121to149oC.Normalairheatercoldendmetaltemperaturesarefrequentlyaslowas93C,aciddewpointcorrosionpotentialexists.2025/6/2288.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕3.Corrosion尾部受熱面低溫腐蝕1)Formationandharm低溫腐蝕及其危害導(dǎo)致空氣預(yù)熱器串孔，大量空氣漏入煙氣中；帶來空氣不足，燃燒惡化，送引風機負荷增加，電耗增大.造成低溫粘結(jié)性積灰，影響傳熱，使排煙溫度升高嚴重腐蝕需更換大量受熱面。2025/6/2298.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕3.Corrosion尾部受熱面低溫腐蝕2)Mechanism低溫腐蝕的機理SO3willincreasethedewpointsignificantlySuchas:thedewpointwillreachat130~150oCwhen0.005%SO3influegasSulfurinfuelSulfurdioxidesSulfurtrioxidessulfuricacidvaport1:煙氣露點tsl:按水蒸氣分壓計算的煙氣露點2025/6/22108.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕2025/6/22118.4Ashdeposit,Corrosion,erosionofbackheatingsurfaces

§8-4尾部受熱面的積灰、磨損和低溫腐蝕3)Influencefactor影響低溫腐蝕的因素Sulfurinafuel燃料中硫分：硫分高，SO3生成多。Hightemperatureflame火焰溫度：溫度高，SO3生成多。Excessairfactor過量空氣系數(shù)：氧氣增加,有利于SO3生成Metaloxidesinash飛灰中的某些成分：鈣鎂氧化物和碳粒吸收SO2，SO3減少Somecatalystinsmoke煙塵中Fe2O3或V2O5等催化劑含量。2025/6/22124)Prevent防止和減輕低溫腐蝕IncreaseT提高壁面溫度采用熱風再循環(huán)（圖10-10)hotairrecirculation

空氣預(yù)熱器進口加裝暖風機（圖10-12)steam-orwater-coilairheatersto