Pre-Treatment Strategies for Optimal Boiler Performance 

Boiler feedwater consists of makeup water plus condensed steam. For makeup, many plants utilize raw water that requires pretreatment with some combination of clarifiers, sand filters and mixed media filters. The resulting water then undergoes additional treatment through reverse osmosis membranes, demineralizers, electrodeionizers, ultrafiltration or other systems. The final low conductivity ultrapure water provides the levels needed for optimal boiler performance.

Utilization of pure condensate instead of makeup water provides tremendous value to the plant by minimizing use of chemicals and energy to produce makeup water. However, condensate inevitably involves the risk of steam cycle contamination from condenser leaks. Returning poor condensate to a boiler may result in reduced heat transfer efficiency, increased blowdown, and associated water, energy and chemical costs. Condensate monitoring may allow early detection of condenser leaks and provides information on total boiler water treatment performance.

Regardless of the water source, problems in water treatment will propagate through the entire steam cycle if not corrected. Maintaining and troubleshooting the equipment utilized to process raw water or condensate constitutes a critical step in the cycle.

Component Name Primary Purpose Methods Typical Monitoring Hach Recommendations
Clarifier/ Softener Remove suspended material to protect more sensitive equipment Gravity or pressure filters
  • Inlet: pH, turbidity, and temperature
  • Gound water: hardness
  • Effluent turbidity (principal determination of clarifier performance)
Differential pH Digital Sensor (DPD1P1)
1720E Low Range Process Turbidimeter and sc200 Controller
2100Q Portable Turbidimeter
2100AN Laboratory Turbidimeter
APA6000 Low Range or High Range Hardness Analyzer
Digital titrator for hardness
DR 5000™ UV-Vis Spectrophotometer
DR 3900™ Benchtop Spectrophotometer
Sand or Multi-Media Filters Remove or reduce suspended solids, organic carbon and colloidal silica from raw water source Coagulation, flocculation and sedimentation using various additives
  • pH
  • TSS
  • Pressure on inlet
  • Differential pressure
sc200 or sc1000 controllers with GLI D3422A2 high purity conductivity sensors
Clearwell Allows disinfectant time for contact with water Chlorine addition
  • Chlorine residual
  • Turbidity
CL17 Free Residual or Total Residual Chlorine Analyzer
CLF10 sc Free and CLT10 sc Total Reagentless Chlorine Sensor
Pocket Colorimeter II (Free and Total Chlorine)
AutoCAT 9000 Chlorine Amperometric Titrator
Reverse Osmosis (RO) Removes dissolved ions from water to minimize loading of demineralizer Membranes
  • SDI (Silt Density Index) on inlet
  • Conductivity
  • Temperature
  • Pressure
  • Bisulfite (chlorine removal upstream of RO)
sc200 or sc1000 controllers with GLI D3422A2 high purity conductivity sensors
Ion Exchange Demineralizers To remove cations and anions from water Ion exchange resins including mixed-bed resins, strong and weak anion and strong and weak cation resins
  •  pH
  • Conductivity
  • Silica
  • Sodium
8362sc High Purity Water Panel
sc200 or sc1000 controllers with GLI D3422A2 high purity conductivity sensors
Series 5000 Silica Analyzer
9240/9245 Sodium Analyzers
Condenser Condense steam for re-use as boiler feedwater Once through or recirculating
  • pH
  • Conductivity
  • Silica
  • Sodium
  • Dissolved Oxygen
8362sc High Purity Water Panel
sc200 or sc1000 controllers with GLI D3422A2 high purity conductivity sensors
Series 5000 Silica Analyzer
9240/9245 Sodium Analyzer
K1100 Dissolved Oxygen Sensor