Curran International | White Papers - Controlling Fouling and Corrosion, Improving Asset Utilization with the Right Coating in Tubing

Solving Power Plant Condenser Tube Problems with Thin Film Conductive Coating Applications

•Evolution of tube ID coating applications

•Improvements in equipment and techniques

•Thin film materials –product enhancements

•In-situ application case historie

Evolving the maintenance model for tubulars

Background of tube ID coating

EPRI-FPC observations

•Tube coating v. retube est. $8M (1989)

•Demonstration project funded 1993:

Tube ID surface prep –achieve NACE 1Materials –ambient cured epoxy phenolic

•Observations:

Proven resistance to “Taprogee”serviceNDE inspection 1997 –corrosion rate lowerSustained long term HT performanceNo penalty to condenser backpressure

Equipment development –tube cleaning

•Standard nozzles inefficient for condenser tube ID cleaning

•University collaboration led to enhanced nozzle design

•High kinetic energy, more efficient cleaning –Mach II blas

“Used”exchanger tubes –cleaned of magnetite scale

•Airless equipment development –filtering, uniform deposition

•Fixed or “flex”lance systems, 2/meters/second spray rate

•Uniform deposition –(+/-) 25 microns -.001”

Application development tube ID coating method

Engineered polymers

•70% of total HTR is tube ID boundary layer drag; •Coating reduces surface tension 30X –elimination of scale; •Sustains “as new”flow rate; maintains flow profile at tube wall; •80% improvement compared to uncoated tubes; •Dialectic barrier between CW and tube wall oxides



: Resistance to heat transfer

(T0) Steam side water film -18%(T1) Steam side fouling –8%(T2) Tube Wall –2%(T3) Water side fouling –33%(T4) Water side film –39%Advanced Polymers: Lustenador & Staub

mproving heat transfer performance

Coating material	BTU/hr-ft2 -F
1993 application –2-3 mils epoxy	0.285
2006 –University of Stellenbosch 3 mils phenol epoxy –solvented coating	0.358
2006 –University of Stellenbosch 3 mils phenol epoxy w/conductive pigments	0.667

•Eskom Power, South Africa –Corroded tubes; restart “mothballedmothballed”plants

•China Light and Power/Alstom –Corroded condenser tubes.

•Cottonwood Power, Texas –Maganese pitting; coated 30% of Unit 1

•Huntley, New Zealand –Partial condenser, recovery of corroded tubes.

•Contact Energy, New Zealand –Partial condenser, corroded tubes. corroded tubes

•Madsen Navigation –Steam ships, recover corroded tubes

•Valero, Aruba –Condensers, coating of full length tube IDs, tubesheets full length tube IDs, tubesheets

•Reliant Avon Lake, Ohio –Inhibit corrosion of cooling water tubes

•CP&L, North Carolina –Tube ID coating to reduce Cu ion discharge

•TVA –Repair and inhibit erosion of Cu/Ni tubes in 3/mps flow.

•Hawaiian Electric –Hydrogen embrittlement, overexpansion of tube ends

Reference work, application case history

Aruba tubesheet and tube IDs, after 8 years salt water service

Cottonwood Energy, Texas –20 gauge SS tubes, manganese attack; coating material wicks/wets in deeply corroded pit

CP&L –tube ID coating -5 years service

Cross section of coating exchanger tube, (50X) coatingfills corrosion attack at the weld seam. Pull tests of tubespulled post coating measured >800 PSI adhesive strength.

Coated tube ID –7 years of cooling water service

Tube ID coating applications

•Changing the equation of tubular equipment maintenance

•Effective cost/short duration v. traditional tube replacement

•Proven performance >45 power plants since 199

Edward Curran, CEO ecurran@curranintl.com www.curranintl.com Booth #530