2025/6/2213.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率鍋爐熱平衡是研究燃料的熱量在鍋爐中利用的情況，有多少被有效利用，有多少變成了熱量損失，這些損失又表現(xiàn)在哪些方面以及它們產(chǎn)生的原因。熱平衡目的是為了有效地提高鍋爐熱效率。鍋爐熱效率是鍋爐的重要技術(shù)經(jīng)濟(jì)指標(biāo)，它表明鍋爐設(shè)備的完善程度和運(yùn)行管理的水平。提高鍋爐熱效率以節(jié)約燃料，是鍋爐運(yùn)行管理的一個重要方面。鍋爐的熱平衡(或熱效率)試驗(yàn)是為了全面評定鍋爐的工作狀況。通過測試分析影響鍋爐熱效率的因素，得出較先進(jìn)的運(yùn)行經(jīng)驗(yàn)數(shù)據(jù)，作為設(shè)計鍋爐和改進(jìn)運(yùn)行的可靠依據(jù)。2025/6/222Boilerefficiencyistheratioofenergyoutputtoenergyinputandisusuallyexpressedasapercentage.Theoutputtermforasteamgeneratoristheenergyabsorbedbytheworkingfluidthatisnotrecoveredwithinthesteamgeneratorenvelope.Itincludestheenergyaddedtothefeedwateranddesuperheatingwatertoproducesaturated/superheatedsteam,reheatsteam,auxiliarysteamandblowdown.

Itdoesnotincludetheenergysuppliedtopreheattheenteringairsuchasairpreheatercoilsteamsuppliedbythesteamgenerator.Theenergyinputtermisthemaximumenergyavailablewhenthefueliscompletelyburned,i.e.,themassflowrateoffuel,MRF,multipliedbythehigherheatingvalueofthefuel.Thisisconventionallyexpressedas:3.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率(p10-17)2025/6/223IntheU.S.,itiscustomarytoexpresssteamgeneratorefficiencyonahigherheatingvaluebasis.Steamgeneratorefficiencymayalsobeexpressedonalowerheatingvaluebasis(commoninEurope).Forthesamemassflowrateoffuel,theLHVefficiencymaybe3to10percentagepointshigherthantheHHVefficiency,dependingupontheamountofH2andH2Ointhefuel.Whencomparingsteamgeneratorefficiencyand/orplantheatrate,theymustbeonthesamebasis,i.e.,HHVorLHV.Efficiencymaybedeterminedbymeasuringthemassflowrateoffuelandsteamgeneratoroutput,whichisreferredtoastheinput-outputmethod(正平衡)theenergybalancemethod

(反平衡).Theenergybalancemethodisgenerallythepreferredmethod.Itisusuallymoreaccuratethantheinput-outputmethod.3.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率(p10-17)2025/6/224Accordingtothelawofconservationofenergy,forsteady-stateconditions,theenergybalanceonthesteamgeneratorenvelopecanbeexpressedas:QRFistheinputfromfuel,Btu/h,QROisthesteamgeneratoroutput,Btu/h,QHBistheenergyrequiredbyheatbalanceforclosure,Btu/h.Theheatbalanceenergyassociatedwiththestreamsenteringthesteamgeneratorenvelopeandtheenergyaddedfromauxiliaryequipmentpowerarecommonlyreferredtoasheatcredits,QRB(Btu/h).Theheatbalanceenergyassociatedwithstreamsleavingthesteamgeneratorandtheheatlosttotheenvironmentarecommonlyreferredtoasheatlosses,QRL(Btu/h).Thissteamgeneratorenergybalancemaybewrittenas:3.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率(p10-17)2025/6/225Thissteamgeneratorenergybalancemaybewrittenas:Whenlossesandcreditsareexpressedasafunctionofpercentinputfromfuel,QPLandQPB,theefficiencymaybecalculatedfrom:3.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率(p10-17)2025/6/2263.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率1.

Constituentsofboilerheatbalance

鍋爐熱平衡的組成以1kg固體燃料或液體燃料(氣體燃料以1Nm3)為單位組成的熱量平衡。(圖3-1)1)Heatbalanceequation

鍋爐熱量平衡方程(單位kg燃料)Heatbalanceequation鍋爐熱量平衡方程百分?jǐn)?shù)形式Q1QrQ2Q6Q3Q4Q5kJ/kg%2025/6/2273.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率1.

Constituentsofboilerheatbalance

鍋爐熱平衡的組成Qr:Heatinputbyanunitfuel

單位燃料帶入鍋爐的熱量,kJ/kgQ1:Boilereffectiveheat

鍋爐有效利用熱量,kJ/kg；Q2:Heatlossduetoexhaustgas

排出煙氣帶走的熱量,排煙熱損失，kJ/kgQ3:Heatlossduetounburnedgas

未燃盡可燃?xì)怏w所帶走的熱量，為氣體不完全燃燒熱損失,kJ/kg；Q4:Heatlossduetounburnedcarboninrefuse

未燃完的固體燃料所帶走的熱量，稱為固體不完全燃燒熱損失;Q5:Heatlossduetoradiation

鍋爐散熱損失，kJ/kg；Q6:Otherheatlosses

灰渣物理熱損失及其他熱損失，kJ/kg。2025/6/2283.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率1.

Constituentsofboilerheatbalance

鍋爐熱平衡的組成2)Heatinputbycombustionfuel

燃料帶入鍋爐的熱量Qr2500:approximateenthalpyofsteaminfluegas,kJ/kga)Sensibleheatoffuel燃料的物理顯熱ir

(1)固體燃料應(yīng)用基比熱：

(2)液體燃料應(yīng)用基比熱b)heatinputbysteamatomization,Qzq

蒸汽帶入熱c)外來熱量Qwlexternalheatspecificheat2025/6/2293.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率2.

Boilerefficiency

鍋爐熱效率1)Boilerefficiencybypositivebalance

鍋爐正平衡熱效率Boilereffectiveheatutilization鍋爐有效利用熱量Qgl，kJ/hB:fuelconsumption,燃料消耗量，kg/hkJ/kg2025/6/22103.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率2.

Boilerefficiency

鍋爐熱效率1)Boilerefficiencybypositivebalance

鍋爐正平衡熱效率Boilereffectiveheatutilizationperhour鍋爐每小時有效利用熱量QglkJ/h；W:watercontentinsaturatedsteam,%r:latentheatofsteam,kJ/kgI’’:enthalpyofsaturatedsteam2025/6/22113.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率2.

Boilerefficiency

鍋爐熱效率1)Boilerefficiencybypositivebalance

鍋爐正平衡熱效率Boilereffectiveheatutilizationperhour鍋爐每小時有效利用熱量QglkJ/s；2025/6/22123.3Boilerheatbalanceandboilerefficiency

§3-3鍋爐熱平衡的組成及鍋爐效率2.

Boilerefficiency

鍋爐熱效率2)Boilerefficiencybynegativebalance

鍋爐反平衡熱效率Calculatetheheatlossesofboiler通過計算各項損失熱效率BoilergrossefficiencyBoilernetefficiency2025/6/22133.3Boilerheatbalanceandboilereff