Polyglass performance in an Aggressive Operating Environment – Absorber of FGD System

Posted On : Thursday, December 8th, 2022 in News

Our partners in India, Kirloskar Corrocoat Pvt Ltd (KCPL), were asked to protect the internals of a new wet limestone absorber on a coal-fired power plant in Tamil Nadu, in Southern India.

The absorber is a critical part of FGD system at the plant and operates in a highly abrasive and corrosive environment. A system offering both high chemical and erosion resistance was essential to be effective in this environment.

FGD Absorber - Outside

 

Polyglass PPV (a holding primer) and Polyglass VEF were selected due to its proven ability to offer superior resistance and performance in aggressive conditions.

As the absorber was 41.5 m high it was divided into 4 zones in order to complete the project;

 

Zone 1: Bottom to 2m shell wall

 

Zone 2: 2m shell wall up to 19.70m and below spray zone.

 

Zone 3: 19.70m shell wall up to 30.20m from bottom (spray zone)

 

Zone 4: 30.2m Shell Wall up to 41.50m from bottom mist eliminator Zone.

 

FGD Absorber before protection

Each zone was blasted, ahead of being primed with Polyglass PPV and then coated with Polyglass VEF via spray application, to minimum DFT of 4mm in Zone 1 and Zone 3, and a minimum DFT of 2mm on Zone 2 and Zone 4. The project was completed over 3 months, with a team of 30 men.

 

Inspection after 6 year’s service;

A KCPL team recently visited the plant to inspect the absorber following 6 years in service. Below are the results:

Zone 1:

  • Inspection was started from the bottom of the absorber using a DFT gauge and visual inspection. DFT’s found were as per specification i.e, Min 4mm
  • Dft measured at bottom, side walls and near to agitator.
  • Visually, the coating was found to be in good condition, without any loss of material and damage.

 

Zone 2:

  • No physical access for Zone 2.
  • Visually, no defects found.

 

Zone 3:

  • Inspection was carried out through manholes at spray header at two locations, i.e. +25m and +27m.
  • DFT was measured up to accessible location and found to be in line with specified i.e Min. 4mm. Visually the coating was found in good condition.

 

Zone 4:

  • Inspection carried out in above mist eliminator zone by entering top portion.
  • DFT measured was found to be ok in all the locations i.e top of the cone and side walls.

 

No defects were found at any location accessible during the inspection and visually the coating was in excellent condition at the areas which could be observed in inaccessible areas

FGD Absorber - following 6 years

Conclusion

Following inspection after 6 years in service, the coating was found to be in good condition without loss of thickness, despite the highly aggressive environment, throughout all zones. The team are confident the coating can further sustain another 10 years without any major issues.

 

 

 

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