Condensate Polishing

Condenser leaks represent a significant risk to power plant operation, as this figure illustrates. Whether in the form of a small tube weep or a catastrophic failure, condensate polishers protect critical power plant components and improve plant reliability. Regardless of the condensate polishing engineering design employed, the system is only as good as the Ion Exchange (IX) resins used. Dow MONOSPHERE™ and AMBERJET™ resins has been protecting valuable power plant assets and improving reliability throughout the world for decades.

A condenser leak at 21.00 contaminates many parts of the plant but is well managed by deep bed condensate polishers.

Three critical performance characteristics must be considered when selecting an IX resin pair for your condensate polishing system:

Kinetic Performance

Sulfate (SO4-2) and chloride (Cl-) ions (measured as cation conductivity) represent the biggest corrosion danger to high pressure drum boilers and once-through steam generators, making of paramount importance the kinetic performance of your IX resin pair in protecting your system under condenser leak conditions. Through careful measurement of mass transfer coefficient, Dow MONOSPHERE and AMBERJET condensate polishing resins have been shown to maintain their kinetic performance for removing chloride and sulfate ions through many years of operation.

Separability

Cross contamination during resin separation and regeneration can result in ionic contamination in condensate polishing systems. As this figure illustrates, the particle size and density control offered by Dow MONOSPHERE and AMBERJET condensate polishing resin result in the best possible resin separation.

Capacity

Most fossil fueled power plants operate at feed water pH of 9.0-9.6 using ammonia (NH3) as the primary base to reduce corrosion. With ammonia concentrations between 0.5-2 ppm, as seen in this figure, ammonia capacity is the primary driver of cost containment in condensate polishing systems. Dow MONOSPHERE and AMBERJET condensate polishing resins offer the highest capacity resins available on the market.

 

Physical Stability

Physical stability is a key characteristic of a good condensate polishing resin. Dow MONOSPHERE and AMBERJET resins demonstrate exceptional physical and osmotic strength under condensate polishing conditions.

Nearly all condensate polishing systems employ external regeneration systems. The mixed IX resins are transferred from a service vessel to a separate vessel where the cation and anion resins are separated prior to regeneration/rinse and then recombined before transfer back to the service vessels. These figures show schematic diagrams of typical external regeneration systems for condensate polishing including one method of managing the interface between cation and anion resin where resin cross contamination is most likely to occur. This amount of resin movement can be quite stressful on the ion exchange resins, making high physical stability a requirement for good performance.

Typical Condensate Polishing External Regeneration System

 

 

Cation – Anion Interface Management Option for Condensate Polishing

 

 

Sodium (Na+) Selectivity

Alternative amines can be used for better partitioning of the amine between the liquid and steam phases, improving pH and corrosion control on wetted surfaces. These amines include morpholine, cyclohexylamine and diethanolamine. Because these amines are more expensive than ammonia, power plants typically operate the condensate polishing systems past the amine break. In these cases, sodium selectivity is the most critical characteristic of the cation exchange resin used in the condensate polishing system. This figure demonstrates how any sodium accumulated on the cation exchange resin is chromatographically displaced at the amine break, creating a spike in sodium content being introduced to the boilers and steam generators. High sodium selectivity reduces the amount of sodium released to the system. AMBERJET™ 2000 H has the highest sodium selectivity of any condensate polishing cation resin available.

Sodium Soking in Amine Cycle Condensate Polishing

 

 

Recommended Operating Conditions Cation Anion
Service Velocity 50 - 125 m/h
Minimum Bed Depth 1 m
Regeneration
Regenerant N2SO4 NaOH
Conventration 5% 4-6%
Dose 125 - 200 g/l 100 - 150 g/l
Rate 2-4 BV/h
Rinse 2-4 BV/h demin water

Purity

Purity is also a key characteristic desired in a condensate polishing resin for high pressure boilers and once-through steam generators. Because chloride is a major contributor to corrosion in power plant equipment and ion exchange resins can be a source of chloride, Dow Water & Process Solutions do not offer chloride form anion exchange resin for condensate polishing applications.

Recommended Products

Product Name Type Ionic Form Matrix Particle Size Recommended Uses
MONOSPHERE 650C (H) SAC H Gel Uniform Recommended for H/OH cycle operation where ammonia is used.
MONOSPHERE 550A (OH) SBA OH Gel Uniform Recommended for H/OH cycle operation where ammonia is used.
AMBERJET 1500 H SAC H Gel Uniform Recommended for SEPREX operations when paired with AMBERJET 9000 OH.
AMBERJET 9000 OH SBA OH Macro Uniform Recommended for SEPREX operations or where potential for anion resin fouling potential is high.
AMBERJET 2000 H SAC H Macro Uniform Recommended for amine-cycle operation. Best paired with AMBERJET 9000 OH.