Power Generation — Boiler Series 3 

Part 3 of 4: Cooling Water In-Leakage to Condensate

Challenge: Identify Condensate Contamination Warning Signals

Condensate purity is essential to total boiler water treatment performance. Analysis of key condensate parameters helps identify and determine the nature of contaminant sources such as steam contamination, corrosion byproducts and in-leakage.

Unfortunately, cooling water in-leakage from the turbine condenser is a common source of condensate return contamination. Dissolved gases and lubricating oils enter through return pumps and pick up dissolved ions and suspended metal particles as corrosion by-products. To prevent these contaminants from entering the boiler, plants often use condensate polishers.

While condenser in-leakage can be detected with conductivity analysis, sodium analysis provides a better method due to its lower detection limit and rapid indication of problems. Sodium analyzers also may be used to monitor mixed-bed condensate polishers for exhaustion.

The most common contaminant in condensate return usually consists of iron or iron oxides. These potentially cause a number of boiler problems including under deposit corrosion, overheating, and blown tubes. Monitoring for excessive hardness, conductivity, and turbidity gives warnings of in-leakage through heat exchangers and condensers. Excessive sodium, phosphate or silica in condensate may indicate carryover problems or condenser leakage. Silica analyzers also indicate the efficiency and regeneration point of condensate polishing systems.

Parameter Benefit Hach Offering
Conductivity Detects contamination. sc200 or sc1000 controllers with GLI D3422A2 high purity conductivity sensors
Copper
Hardness
Hydrazine
Iron
Detects suspected contaminants in the condensate. DR 5000™ UV-Vis Spectrophotometer
DR 3900™ Benchtop Spectrophotometer
pH Determines potential corrosiveness of water. 8362sc High Purity pH/ORP System with sc200 or sc1000 controller
Phosphate Indicates carryover problems from the boiler. Series 5000 Phosphate Analyzer
DR 5000 UV-Vis Spectrophotometer
DR 3900 Benchtop Spectrophotometer
Silica Detects breakthrough of solids resulting from resin bed exhaustion. Series 5000 Silica Analyzer
Sodium Detects condenser leaks. Detects breakthrough of solids resulting from resin bed exhaustion. 9240/9245 Sodium Analyzers
TOC Detects organic contaminants, particularly where the quality of the condensate return varies widely. BioTector Online TOC Analyzer
DR 5000 UV-Vis Spectrophotometer
DR 3900 Benchtop Spectrophotometer