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CONDENSATE WATER BOX HEATER TANK STEAM SPRAY CHAMBER TRAY STACK COUNTERCURRENT FLOW VENTS MAKEUP
GE Power & Water Water & Process Technologies
VALVES, NOZZLES
Process 8.6 MT/Hr
Demin H2O pH/Cond/SiO2
E-8129
2.4 MT/Hr
Steam Drum C-6130
LP Steam Condensate pH/Cond/F e Deaerator C-8108 EO Reactor E-6101
Blowdown
OS7785 O2 Scav
贵厂锅炉现状
GE Power & Water Water & Process Technologies
3、过热蒸汽SiO2含量高达296ppb，饱和 蒸汽SiO2含量高达140ppb，国标控制要 求为20ppb，严重超标 ； 危害：蒸汽中SiO2含量超标，会在汽轮机 等表面形成硅酸盐垢，难以清洗，会严重 影响设备的稳定运行，增加运行能耗 解决方案：1、加大排污； 2、检查混床；
STEAM EQUALIZERS
DOWNCOMER
STORAGE TANK
TO FEEDWATER PUMP
GE PROPRIETARY & CONFIDENTIAL
O2 Solubility in Water
GE PROPRIETARY & CONFIDENTIAL
Causes of Low pH Corrosion
Acid leak from demin water plant
GE Power & Water Water & Process Technologies
Acid contamination in boiler make-up water or condensate return
BFW and condensate pH = 9.2 – 9.6 for all ferrous metallurgy and for Ferrous/Cu mixed metallurgy system pH = 8.8 – 9.2 Boiler water pH typically 9.3 – 10.3 at 5 15 ppm PO4
GE PROPRIETARY & CONFIDENTIAL
EO Waste Heat Boiler Schematic
75.4 MT/Hr
MP Steam 16 MPa
pH/Cond/SiO2
GE Power & Water Water & Process Technologies Process Ethylene + O2
Organic contamination in condensate from process leak
Localized concentration of mineral acids eg, HCl, H2SO4 Cooling water contamination in condensate return from heat exchanger leak
GE Power & Water Water & Process Technologies
Dissolved O2 Removal
Mechanical deaeration in deaerator
Raise boiler feed water temp to 1-2 C of saturation temperature by steam stripping Remove dissolved O2 to < 10 ppb
Relative Corrosive Attack
8.5 pH
源自文库
12.7 pH
Safe Range
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
GE Power & Water Water & Process Technologies
Dissolved O2 Corrosion
贵厂锅炉现状
今天现场分析，发现如下问题： 1、炉水PH 8.98，偏低，国标为9.0~11.0， 正常控制一般在9.5~10.5； 2、炉水Fe含量超标（0.69ppm）； 危害：过低的PH会造成锅炉腐蚀，产生爆 管现象； 解决方案：采用协调磷酸盐控制炉水PH， 防止腐蚀
GE PROPRIETARY & CONFIDENTIAL
Such high pH can occur due to concentration of free caustic (NaOH) on steam generating heat transfer surfaces (eg, boiler riser tubes) to > 2000 ppm under certain operating/design condition (high heat flux/low flow/water steam 2phase flow)
At temp > 100 C, dissolved O2 in water can cause O2 pitting corrosion O2 pitting corrosion is very rapid and as such, it can cause tube leak in relatively short time To eliminate dissolved O2 corrosion in a boiler system (feed water/boiler water/condensate) dissolved O2 must be removed and maintained at less than 10 ppb
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
贵厂锅炉现状
5、锅炉凝结水Fe含量0.69ppm，严重超 标（国标≤0.1ppm）； 危害：蒸汽未处理，造成凝结水PH偏低， 腐蚀设备管道，而且过高的凝结水Fe含量 会带入锅炉，会进一步对锅炉产生腐蚀， 影响锅炉的稳定运行。 解决方案：1、投加中和胺，调整蒸汽PH； 2、如果条件允许，增加凝 结水 精处理装置；
Boiler Water
Alkaline PO4, OptiSperse HP2650
Stainless steel metallurgy is resistance low/high pH and dissolved O2 corrosion
GE PROPRIETARY & CONFIDENTIAL
O2 Scavenger
Residual dissolved O2 to be removed by organic O2 scavenger, CorTrol OS7785 CorTrol OS7785 is hydroquinone
GE PROPRIETARY & CONFIDENTIAL
Deaerator – Spray & Tray
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
High pH Corrosion
In boiler operating temperature, pH > 12.5 is corrosive to carbon steel
Boiler Corrosion
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
Low pH Corrosion
Boiler metallurgy typically is made of carbon steel At water pH < 7.0 (acidic), it is corrosive to carbon steel Optimum pH control range
GE Power & Water Water & Process Technologies
Boiler Water Treatment
Technical Training
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
NaOH leak from demin water plant NaOH or KOH contamination in condensate from process leak
Localized concentration of free NaOH due to high heat flux or steam blanketing
Prevent Deposition cause by
Corrosion products (iron/copper oxides) Insoluble minerals salts (Ca/Mg/SiO2)
Maintain Steam Purity
Impurities in steam may poison process catalyst Minimizes boiler water carryover
GE PROPRIETARY & CONFIDENTIAL
pH Control to Minimize Corrosion
GE Power & Water Water & Process Technologies
Boiler feed water and condensate
Use of volatile neutralizing amines, Steamate NA0880
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
贵厂锅炉现状
4、锅炉除氧器目前采用的是热力除氧，经 现场测试，溶解氧超出了仪器测试范围 （40ppb），通过试样颜色预估在100ppb 左右（国标≤15ppb，正常控制≤10ppb）； 危害：过高的氧进入锅炉，会造成氧腐蚀， 进而会发生锅炉爆管。 解决方案：1、加强热力除氧控制； 2、增加化学除氧；
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
Causes of High pH
NaOH contamination in boiler make up water or condensate return
GE PROPRIETARY & CONFIDENTIAL
Corrosive
Corrosive
GE Power & Water Water & Process Technologies
GE PROPRIETARY & CONFIDENTIAL
HIGH OR LOW BOILER WATER pH CORRODES BOILER STEEL
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
Boiler Water Treatment
Objectives
Prevent Corrosion cause by
Acidic pH (< 7.0) Too high pH (>12.5) Dissolved Oxygen in BFW
pH/Cond PO4/SiO2
EO Reactor Cooler E-6104 BFW
HP265 0 PO4 GE PROPRIETARY & CONFIDENTIAL
NA0880 Amine
pH/Cond SiO2/D. O2/Fe EO
GE Power & Water Water & Process Technologies
GE Power & Water Water & Process Technologies
VALVES, NOZZLES
Process 8.6 MT/Hr
Demin H2O pH/Cond/SiO2
E-8129
2.4 MT/Hr
Steam Drum C-6130
LP Steam Condensate pH/Cond/F e Deaerator C-8108 EO Reactor E-6101
Blowdown
OS7785 O2 Scav
贵厂锅炉现状
GE Power & Water Water & Process Technologies
3、过热蒸汽SiO2含量高达296ppb，饱和 蒸汽SiO2含量高达140ppb，国标控制要 求为20ppb，严重超标 ； 危害：蒸汽中SiO2含量超标，会在汽轮机 等表面形成硅酸盐垢，难以清洗，会严重 影响设备的稳定运行，增加运行能耗 解决方案：1、加大排污； 2、检查混床；
STEAM EQUALIZERS
DOWNCOMER
STORAGE TANK
TO FEEDWATER PUMP
GE PROPRIETARY & CONFIDENTIAL
O2 Solubility in Water
GE PROPRIETARY & CONFIDENTIAL
Causes of Low pH Corrosion
Acid leak from demin water plant
GE Power & Water Water & Process Technologies
Acid contamination in boiler make-up water or condensate return
BFW and condensate pH = 9.2 – 9.6 for all ferrous metallurgy and for Ferrous/Cu mixed metallurgy system pH = 8.8 – 9.2 Boiler water pH typically 9.3 – 10.3 at 5 15 ppm PO4
GE PROPRIETARY & CONFIDENTIAL
EO Waste Heat Boiler Schematic
75.4 MT/Hr
MP Steam 16 MPa
pH/Cond/SiO2
GE Power & Water Water & Process Technologies Process Ethylene + O2
Organic contamination in condensate from process leak
Localized concentration of mineral acids eg, HCl, H2SO4 Cooling water contamination in condensate return from heat exchanger leak
GE Power & Water Water & Process Technologies
Dissolved O2 Removal
Mechanical deaeration in deaerator
Raise boiler feed water temp to 1-2 C of saturation temperature by steam stripping Remove dissolved O2 to < 10 ppb
Relative Corrosive Attack
8.5 pH
源自文库
12.7 pH
Safe Range
1 2 3 4 5 6 7 8 9 10 11 12 13 14
pH
GE Power & Water Water & Process Technologies
Dissolved O2 Corrosion
贵厂锅炉现状
今天现场分析，发现如下问题： 1、炉水PH 8.98，偏低，国标为9.0~11.0， 正常控制一般在9.5~10.5； 2、炉水Fe含量超标（0.69ppm）； 危害：过低的PH会造成锅炉腐蚀，产生爆 管现象； 解决方案：采用协调磷酸盐控制炉水PH， 防止腐蚀
GE PROPRIETARY & CONFIDENTIAL
Such high pH can occur due to concentration of free caustic (NaOH) on steam generating heat transfer surfaces (eg, boiler riser tubes) to > 2000 ppm under certain operating/design condition (high heat flux/low flow/water steam 2phase flow)
At temp > 100 C, dissolved O2 in water can cause O2 pitting corrosion O2 pitting corrosion is very rapid and as such, it can cause tube leak in relatively short time To eliminate dissolved O2 corrosion in a boiler system (feed water/boiler water/condensate) dissolved O2 must be removed and maintained at less than 10 ppb
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
贵厂锅炉现状
5、锅炉凝结水Fe含量0.69ppm，严重超 标（国标≤0.1ppm）； 危害：蒸汽未处理，造成凝结水PH偏低， 腐蚀设备管道，而且过高的凝结水Fe含量 会带入锅炉，会进一步对锅炉产生腐蚀， 影响锅炉的稳定运行。 解决方案：1、投加中和胺，调整蒸汽PH； 2、如果条件允许，增加凝 结水 精处理装置；
Boiler Water
Alkaline PO4, OptiSperse HP2650
Stainless steel metallurgy is resistance low/high pH and dissolved O2 corrosion
GE PROPRIETARY & CONFIDENTIAL
O2 Scavenger
Residual dissolved O2 to be removed by organic O2 scavenger, CorTrol OS7785 CorTrol OS7785 is hydroquinone
GE PROPRIETARY & CONFIDENTIAL
Deaerator – Spray & Tray
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
High pH Corrosion
In boiler operating temperature, pH > 12.5 is corrosive to carbon steel
Boiler Corrosion
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
Low pH Corrosion
Boiler metallurgy typically is made of carbon steel At water pH < 7.0 (acidic), it is corrosive to carbon steel Optimum pH control range
GE Power & Water Water & Process Technologies
Boiler Water Treatment
Technical Training
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
NaOH leak from demin water plant NaOH or KOH contamination in condensate from process leak
Localized concentration of free NaOH due to high heat flux or steam blanketing
Prevent Deposition cause by
Corrosion products (iron/copper oxides) Insoluble minerals salts (Ca/Mg/SiO2)
Maintain Steam Purity
Impurities in steam may poison process catalyst Minimizes boiler water carryover
GE PROPRIETARY & CONFIDENTIAL
pH Control to Minimize Corrosion
GE Power & Water Water & Process Technologies
Boiler feed water and condensate
Use of volatile neutralizing amines, Steamate NA0880
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
贵厂锅炉现状
4、锅炉除氧器目前采用的是热力除氧，经 现场测试，溶解氧超出了仪器测试范围 （40ppb），通过试样颜色预估在100ppb 左右（国标≤15ppb，正常控制≤10ppb）； 危害：过高的氧进入锅炉，会造成氧腐蚀， 进而会发生锅炉爆管。 解决方案：1、加强热力除氧控制； 2、增加化学除氧；
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
Causes of High pH
NaOH contamination in boiler make up water or condensate return
GE PROPRIETARY & CONFIDENTIAL
Corrosive
Corrosive
GE Power & Water Water & Process Technologies
GE PROPRIETARY & CONFIDENTIAL
HIGH OR LOW BOILER WATER pH CORRODES BOILER STEEL
GE PROPRIETARY & CONFIDENTIAL
GE Power & Water Water & Process Technologies
Boiler Water Treatment
Objectives
Prevent Corrosion cause by
Acidic pH (< 7.0) Too high pH (>12.5) Dissolved Oxygen in BFW
pH/Cond PO4/SiO2
EO Reactor Cooler E-6104 BFW
HP265 0 PO4 GE PROPRIETARY & CONFIDENTIAL
NA0880 Amine
pH/Cond SiO2/D. O2/Fe EO
GE Power & Water Water & Process Technologies