Water Requirement for Coal/Biomass Packaged Steam Boiler

12/05/2017


Water quality is significant related to industrial boiler safety operation, if water quality does not meet the requirements, it will caused water limescale caused by deposited sand and mud at drum and header lower part. It destroys the water circulation, causes the tube overheated, deformation, pipe breaking and even boiler cracks.
 
Then, what is the specific requirement for coal/biomass fired packaged boilers?








The industrial boiler supplied water should not contain sediments, such as silt. The boiler water must comply with GB/T1576-2008 "industrial boiler water requirements". The water for Zhongding coal/biomass fired packaged boiler should meet the specification of the following table:


Items Rated Steam Pressure (MPa) P≤1.0 1.0<P≤1.6 1.6<P≤2.5
 Feed Water Type Soften water Demineralized water Soften water Demineralized water Soften water Demineralized water
Feed
Water
Turbidity/FTU ≤5.0 ≤2.0 ≤5.0 ≤2.0 ≤5.0 ≤2.0
Hardness/(mmmol/L) ≤0.030 ≤0.030 ≤0.030 ≤0.030 ≤0.030 ≤0.030
pH value(25℃) 7.0~9.0 8.0~9.5 7.0~9.0 8.0~9.5 7.0~9.0 8.0~9.5
Dissolved oxygen a(mg/L) ≤0.10 ≤0.10 ≤0.10 ≤0.050 ≤0.050 ≤0.050
Oil/(mg/L) ≤2.0 ≤2.0 ≤2.0 ≤2.0 ≤2.0 ≤2.0
Total Iron/(mg/L) ≤0.30 ≤0.30 ≤0.30 ≤0.30 ≤0.30 ≤0.10
Electrical Conductivity
(25℃)/(μS/cm)
- - ≤5.5×102 ≤1.1×102 ≤5.0×102 ≤1.0×102
Boiler Water   
Total Alkalinity
b/(mmol/L)
Without Superheater 6.0~26.0 ≤10.0 6.0~24.0 ≤10.0 6.0~16.0 ≤8.0
With Superheater - - ≤14.0 ≤10.0 ≤12.0 ≤8.0
Phenolphthalein alkalinity/(mmol/L) Without Superheater 4.0~18.0 ≤6.0 4.0~16.0 ≤6.0 4.0~12.0 ≤5.0
With Superheater - - ≤10.0 ≤6.0 ≤8.0 ≤5.0
pH value(25℃) 10.0~12.0 10.0~12.0 10.0~12.0 10.0~12.0 10.0~12.0 10.0~12.0
Dissolved solid matter/(mg/L) Without Superheater ≤4.0×103 ≤4.0×103 ≤3.5×103 ≤3.5×103 ≤3.0×103 ≤3.0×103
With Superheater - - ≤3.0×103 ≤3.0×103 ≤2.5×103 ≤2.5×103
 Phosphate c(mg/L) - - 10.0~30.0 10.0~30.0 10.0~30.0 10.0~30.0
 Sulfite d(mg/L) - - 10.0~30.0 10.0~30.0 10.0~30.0 10.0~30.0
 Relative alkalinity e <0.20 <0.20 <0.20 <0.20 <0.20 <0.20
Note 1: Measurement unit of hardness and alkalinity are the basic unit of volume concentration per unit price.
Note 2: Turn on a idle (spare) boiler, when the concentration ratio of boiler water reach the normal value, the boiler water quality should meet the standard requirements.
a. Dissolved oxygen control values is applicable to the supplied water treated by deaerating plant. When the rated evaporation capacity≧10t/h, the supplied water should be deoxidized. For the boiler which rated evaporation capacity<10t/h, if there are localized corrosion, oxygen removing measures should be taken.
B. For the boiler do not require high quality water, and without superheater, the upper limited value of boiler water total alkalinity could be properly relaxed, but the pH value (25℃) could not exceed the upper limited value.
c. Applicable to add phosphate inhibitor into boiler. When using other inhibitors, scale inhibitors residual volume should be consistent with the standard specified by the manufacturer.
d. Applicable to add sulfites deoxidizer into supplied water. When using other dexidizers, deoxygenation residual volume should be consistent with the standard specified by manufacturer.
e. For the whole welding structure boiler, the related alkalinity could not be limited.

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Product :
 Gas-fired(oil-fired)boilers          Coal-fired boilers  Biomass-fired boilers           Thermal fluid heaters
Power/Capacity :
Hot water/oil           0.7-14MW          14.1-21MW  21.1-29MW            29.1-75MW
Steam                     1-10t/h               11-20t/h  21-90t/h                  91-140t/h
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