船舶鍋爐水處理_圖文

1、Drew Marine 鍋爐水處理Primary Functions of BoilerDrew Marine Water Treatment Program鍋爐水處理基本功用To inhibit the corrosion processthroughout the system阻止系統(tǒng)腐蝕To render any scale formingconstituents harmless in the boilerwater防止水垢對鍋爐系統(tǒng)的危害To prevent carry-over of solids from theboiler to the power and heating pl

2、antsystem防止鍋爐雜質(zhì)進入加熱及動力系統(tǒng)Drew MarineCorrosionScaleDeposits Water Related Problems與水相關的問題Drew Marine Scale Formation水垢的形成Common Water Impurities水中的雜質(zhì)Calcium 鈣Magnesium 鎂Silica 硅Drew Marine Principal water-related problems scaling水相關問題水垢Scaling is the formation of a crystalline, interlocked layer of mi

3、neral substances on heat transfer surfaces水垢是礦物質(zhì)在傳熱面上形成的結晶層Severe scaling normally typically occurs only within the boiler 嚴重的水垢問題多出現(xiàn)于鍋爐內(nèi)Typical scale formed are predominantly acarbonate/sulfate complex of Calcium and magnesium典型的水垢均為鈣,鎂離子與碳酸,硫酸離子的復雜化合物Calcium carbonate CaCO3Magnesium sulfate MgSO4

4、Principal water-related problems scaling水相關問題水垢If unchecked, scaling will lower boiler efficiency 若不加以關注,水垢將會降低鍋爐效率It will retard heat transfer 阻止熱傳導Eventually scale buildup will cause the tubes to overheat and rupture 更有可能造成水管過熱及損壞 Scale can also accelerate corrosion 水垢也可能加重腐蝕 Scales 水垢Calcium Carb

5、onate Ca(HCO 32CaCO 3+ CO 2+ H 2OCalcium SulfateCaSO 4+ 2H 2O 4.2H 2O Magnesium HydroxideMgCO 3+ H 2O Mg(OH2+ CO 2Drew Marine Solubility of CaSO4 溶解度表 Heavily Scaled-TubeDrew Marine嚴重腐蝕的水管Prone to Under-Deposit Corrosion 沉積物下腐蝕Drew Marine Scale and Iron Oxide Mixtures水垢與氧化鐵的混合Drew Marine Heavily Sca

6、led-Tube嚴重結垢的水管 Temperature Gradient Across Fouled TubeTube Wall Deposit Temperature of Saturated Steam Temp Tube Wall Deposit Heat Input Concentration Gradient Across DepositSolids Concentrate at Tube Bulk Water ConcentratesDeposits Insulate Boiler Tubes 結垢使鍋爐水管被絕熱Deposits insulate tubes andcause o

7、verheating結垢使鍋爐水管傳熱能力降低引起過熱 Temp at tube wall is higher than temp across porous deposit管壁溫度高于沉積物外側的溫度 Dissolved solids concentrate at tube wall & under deposit corrosion occurs 在管壁處出現(xiàn)溶解顆粒濃度及沉積物下腐蝕Bulk Steam Water Mixture 沉積物下腐蝕Once there is a deposit or scale, cathode and anode polarity cell can

8、 be set-up一但出現(xiàn)沉積物,就伴隨著微陰,陽極單元的出現(xiàn)。And the metal under the deposit will be anodic 沉積物下的金屬即為陽極Oxygen present in the boiler water will accelerate corrosion 氧的存在加速了腐蝕的發(fā)生Anodic Reaction陽極反應Fe0Fe+ 2eUnder-Deposit Corrosion沉積物下腐蝕Under-depositCorrosionProfile View ofDrew Marine Under Deposit CorrosionUnderDe

9、positCorrosionPrincipal water-related problemsDrew Marine sludge 水相關問題淤泥Sludge may be a combination of any suspended materials in the water, and it includes:淤泥包括水中各類懸浮物:Loose corrosion products, insoluble mineral precipitates and oil松散的腐蝕物,不可溶礦物質(zhì)及油Significant proportion of suspended material are gen

10、erated outside the boiler鍋爐外產(chǎn)生的懸浮物占了較大部分Oil contamination 油污染Drew Marine Principal water-related problemssludge 水相關問題淤泥“Baked-on sludge”on heat transfer surface acts as a heat insulator 固化的淤泥影響熱傳導Excessive sludge loading from outside boiler may distorts the relationship of suspended to soluble const

11、ituents of the boiler water過量的外來懸浮物會影響爐水中的可溶物This will render in-built program controls less effective 以至影響水處理程序的效果Liquid Coagulant -Sodium Carboxymethylcelluloseto bring sludges to low point to be blown-down. Liquid Coagulant 可對淤泥進行處理,使之容易被排污排出Principal water-related problemsDrew Marine corrosion 水

12、相關問題腐蝕4 main categories of corrosion which will damage a boiler/feed system if left unchecked are:4種有害于鍋爐的腐蝕形式Mineral acid corrosion -mostly in boiler礦物腐蝕主要發(fā)生在鍋爐內(nèi)Carbonic acid corrosion -mostly in thecondensate碳酸腐蝕主要發(fā)生在冷凝器Oxygen corrosion -most severe in boiler氧腐蝕主要發(fā)生在鍋爐內(nèi)Differential concentration (

13、crevice corrosion -縫隙腐蝕主要發(fā)生在鍋爐內(nèi) Principal water-related problemsmineral acid corrosion 水相關問題礦物酸性腐蝕Seawater ingress, condenser inleakage and/or distiller carryover creates mineral acids in the boiler 海水侵入,冷凝器滲漏及造水機泄露均會造成礦物酸性腐蝕Mineral Acid corrosion 礦物酸性腐蝕Fe + 2HCl = FeCl 2 + H 2Maintain “P ”alkalinit

14、y between 100 -150 ppm and “T ”alkalinity less than 2 “P ”alkalinity or pH 10.8 -11.0 維持酚酞堿度在100 150 ppm ,總堿度低于2倍酚酞堿度或PH 10.8-111234567891011121314Theoretical Corrosion RateCorrosive Action Under Normal Boiler ConditionsEffect of High Oxygen ContentGeneral WastagePitting AttackIncreased FoamingI s o

15、 l a t e d P i t t i n g R e c o m m e n d e d A l k a l i n i t yEffect Of pH On The Rate Of CorrosionpH 值于腐蝕率關系Drew MarineAcidity, Alkalinity and pH Ranges酸,堿pH 值Free Mineral Acidity (FMACO 2escapes quickly into environment5000mg/l500505Bicarbonate AlkalinityFree CO 2GasAcidity mg/l CaCO 255050050

16、00mg/lOH Alkalinity mg/l CaCO 2Carbonate AlkalinityHydroxyl AlkalinityM e t h y l O r a n g e E n d p o i n tN e u t r a l i y H = O H“M ”P h e n o l p h t h a l e n E n d p o i n t“P ”pHPrincipal water-related problemsoxygen corrosion 水相關問題氧腐蝕Direct corrosive attack on boiler steel by oxygen occurs

17、 by cathodic depolarization of electrochemical cells at the metal/water interface 在水與金屬的界面上,氧參與微電化腐蝕陰極,直接侵蝕鍋爐鐵質(zhì)Most low pressure systems subjected to atmospheric oxygen ingress 大多數(shù)低壓鍋爐中均受到氧的侵入Keep cascade tank temperature as high as possible 保持盡量高的熱水井溫度Reduce the remaining dissolved oxygen with an o

18、xygen scavenger 用除氧劑消除殘余氧份 Effects of Oxygen Corrosion氧腐蝕的危害Most severe in boiler在鍋爐內(nèi)較為嚴重Metal ions Precipitate as Oxides金屬轉(zhuǎn)化為氧化物Reduce Heat Transfer 阻隔熱傳導Lower than rated capacity降低鍋爐產(chǎn)量Equipment Failures 導致設備失效Repair, and Replacement 增加維修及更新費用 Oxygen Corrosion Control氧腐蝕控制Mechanical Pre-treatment機械

19、除氧Chemical to scavenge the remaining dissolved oxygen用化學劑驅(qū)除剩余氧份Drew Marine1284-121436688110Temperature in Degrees CentigradeOxygen Content ml per literSolubility Of Oxygen In Water氧在水中溶解度與溫度的關系At Atmospheric PressureCorrosion rate,mm per year penetration24681049°C 32°C 9°C Effects Of

20、Oxygen Concentrations氧濃度與腐蝕率關系Mild effect at low temp Increasing temperature increases corrosion rate Corrosion 氧腐蝕Oxygen PittingOxygen CorrosionDrew Marine Corrosion氧腐蝕Occurs in anypart of steamPitting generatingsystem 可能出現(xiàn)在蒸汽系統(tǒng)任何部位Readilyrecognized bysharp-edgedpits其特征為邊緣比較鋒利Drew Marine Oxygen Pit

21、ting Drew Marine Principal water-related problemscarbonic acid corrosion 水相關問題碳酸腐蝕Carbonic acid is formed when CO2 dissolve in the condensate 二氧化碳溶于凝水,形成碳酸腐蝕CO2 is generated by the thermal breakdown of bicarbonates in seawater ingress二氧化碳源自于有機物分解Carbonic Acid corrosion 碳酸腐蝕CO2+ H2O = H2CO3Cu+ + H2CO

22、3= CuHCO3+ H+Fe + 2H2CO3 = Fe(HCO32+ H2Feeding and recycling of a neutralizing amine投放中和劑進行中和Drew Marine Results of Low Condensate pHCondensate System CorrosionpH值低引起的冷凝系統(tǒng)腐蝕GroovingThinningDrew Marine Carbonic Acid CorrosionLow pH CorrosionDrew Marine Different Type Treatment Programs for Low &

23、MediumPressure Boilers中低壓鍋爐不同類型的處理程序Drew MarineLP BWT Programs低壓鍋爐水處理劑程序Drew Standard Boiler Treatment Program標準鍋爐水處理劑程序Drew AGK-100 Boiler & FeedwaterTreatment program AGK-100鍋爐水處理劑Drewplex AT and OXDrewplex AT and AmerzineDrew Marine BWT Program Selection Criteria鍋爐水處理劑程序選擇準則Drew Marine Some S

24、election Criteria選擇準則Quality of make-up water 補給水質(zhì)量Quantity of make-up water daily日常補給水數(shù)量After-boiler distribution network鍋爐后管路系統(tǒng)Dosing and testing simplicity投藥及化驗的簡便性Drew Marine Low & Medium PressDrew Marine Boiler Treatment Program中低壓鍋爐標準處理程序Alkalinity Control 堿度控制GCHardness Control 硬度控制Adjunc

25、t -BOxygen Scavenger/Corrosion Inhibitor 除氧/腐蝕抑制劑AmerzineDrewplex OX -(DEHACondensate Control 冷凝水控制SLCC ADrew Marine Alkalinity Control 堿性控制-Ameroid GCTo raise the boiler water alkalinity, in order to maintain the hydroxyl ion concentration in the optimum range for the formation of goodprotective ma

26、gnetite on the steel surfaces 提高鍋爐水堿性,保持烴基離子的理想含量,有利于鋼表面形成保護膜。Fe + 2NaOH Na 2FeO 2+ H 2Na 2FeO 2+ 4H 2O 6NaOH + Fe 3O 4+ H 2 And to help in the formation of non -adherent sludge instead of scale when hardness enters the boiler 在硬物進入鍋爐時,有利于形成無附著性淤渣而無水垢Drew MarineIt reacts with the bicarbonates and ch

27、lorides of magnesium and calcium; to precipitate harmless non -adherent sludge and sodium chloride which remains in solution 氫氧化鈉與重碳酸鹽及氯化鎂,氯化鈣作用,形成無附著性的淤泥和可溶的氯化鈉 MgCl 2+ 2NaOH Heat Mg(OH2+ 2NaCl Exposed to Atmosphere, NaOH absorbs CO 2to form NaCO 3氫氧化鈉將吸收大氣中的二氧化碳形成碳酸鈉Alkalinity Control 堿性控制-Ameroid

28、 GCDrew Marine Hardness Control硬度控制-Adjunct BTo provide a phosphate reserve in boiler 提供在鍋爐中磷酸根的含量To precipitate calcium as calcium phosphate, a soft non-adherent sludgethat can easily be blowdown使鈣形成磷酸鈣,無附著性,容易排污The carbonates, sulfates and other ions combine with sodium and remain insolution碳酸,硫酸及

29、其他離子和鈉生成可溶解物Drew MarinePhosphate Hide-outphenomenon磷酸根隱藏現(xiàn)象This phenomenon is characterized by,Abnormally fast loss of phosphate residual from boiler water during normal steaming 此現(xiàn)象表現(xiàn)為,在正常運行中磷酸根殘留濃度反常地迅速變小And re-occurrence of a high phosphate residual when shut down or operated at a low steaming rat

30、e在停爐或蒸汽產(chǎn)量低時,磷酸根殘留濃度又出現(xiàn)了This due to the relatively limited solubility of sodium phosphate compounds at high temperature 歸因于高溫下的磷酸鈉的相對低溶解性Drew MarineIn a dirty boiler, the concentrating effect is great enough that the sodium phosphate forms a dry salt in the deposit 在較臟鍋爐中,磷酸鈉鹽會濃縮沉積成固態(tài)鹽 When the heat

31、on surfaces with hide -out is reduced or removed this salt dissolves in the boiler water 當表面熱量減少時,該沉積鹽會溶解回鍋爐水中Phosphate Hide-outphenomenon磷酸根隱藏現(xiàn)象Drew MarineCorrosion Inhibitor/Oxygen ScavengerAmerzine 除氧抑蝕劑To scavenge the residual dissolved oxygen 消除溶解氧It also reacts with Ferric Oxide (Fe 2O 3 to fo

32、rm black magnetite, Ferrous Oxide (Fe 3O 4 which retards corrosion 它也會與Fe 2O 3反應生成Fe 3O 4而阻止腐蝕It also converts the Cupric Oxide (CUO on condenser tubes to the protective Cuprous Oxide CU 2O film 在冷凝管使CUO 轉(zhuǎn)化為保護性的CU 2O Disadvantage -identified as a Carcinogen 弱點-可能致癌Drew Marine Hydrazine Properties 聯(lián)氨

33、特性Hydrazine reacts very slowly at <1350C to form nitrogen and water在<1350C 時聯(lián)氨緩慢反應成氮和水Hydrazine optimal activity temperature is approximately 1770C聯(lián)氨的理想溫度為1770CAt above 2040C, hydrazine can decompose to form nitrogen, hydrogen and ammonia在2040C,聯(lián)氨會分解成氮,氫和氨。Ammonia gives good corrosion protecti

34、on to copper & copper alloy components of the system in the absence of dissolved oxygen在沒有溶解氧的情況下,氨對銅和銅合金有很好的防腐作用DiethylhydroxylamineDrew Marine 最新除氧劑Drewplex OXVolatilizes & transported by steam throughout the boiler & condensate system通過蒸汽在鍋爐和冷凝系統(tǒng)中揮發(fā)輸送Provides ferrous and non-ferrous m

35、etal passivation in pre-boiler, boiler and after boiler sections在鍋爐中使鐵及其他金屬鈍化Good oxygen scavenger良好的除氧劑Does not add dissolved solids to boiler water不會在鍋爐水中增加溶解顆粒Low toxicity低毒性Drew MarineOther Means toScavenge Oxygen 其他除氧方式Deaerator除氧器Maintain cascade tank temperature as high as possible without losing pump suction盡量維持熱水井高溫Water at 100C at atmospheric pressure usually contains between 8 to 10 mg/liter (ppm