Cleaning Techniques for Cooling Systems and...

Cleaning Techniques for Cooling Systems and Boilers

Property of ChemTreat – do not reproduce without permission

Cleaning Applications in Industrial lUtility Systems

• Pre‐Operational Cleaning and Passivationp g• Removal of Organic Buildup caused by leaks or biofilms

– Exchanger degreasing

• Removal of Scale • Rust Removal and Passivation

li l i• Cooling Tower Cleaning • Boilers

Resin and Membrane Cleaning– Resin and Membrane Cleaning– Boil Outs– Scale or Iron removal


Pre‐Operational CleaningPre Operational Cleaning

• Cooling Systems

• Heat Exchangers

• Piping• Piping

• Boilers

The process will vary based on metallurgy.


Problems Associated with FouledProblems Associated with Fouled Systems

• Corrosion by‐product

• Scale• Scale

• Microbiological growth

• Inefficient heat transferInefficient heat transfer

• Reduced Flow

• Increased Corrosion


Cleaning Reduces Operating Costs

• Extending equipment life

• Reducing unscheduled d idowntime

• Energy conservation– Pump operationPump operation

– Heat transfer

– Chiller efficiency

d k h l h• Improved worker health and safety


Primary System Contaminants and Issues

Contaminant IssuesHardness Salts Scaling and DepositsSilica ScaleAlkalinity and CO2 Scale and CorrosionIron and Manganese DepositionSuspended Solids and Organics

Deposition and Microbiological Food SourceOrganics Microbiological Food Source

Oxygen Corrosion


Typical Root Causes

• Water sourceC t i t i k t– Contaminants in makeup water

– Corrosive water– System leaks– Poor or no filtration

• System chemistry– Lack of treatment– Poor control

Corrosion– Corrosion• Microbiological

– Under deposit– Stagnant conditionsg– Process leaks

• Gadgets• Air borne contaminants


“I shut off the bleed valve to save water.”


Water treatment was ignored for 3 years.

Scale bridged between evaporative condenser tubes.

This plant saved aThis plant saved a lot of chemical purchases!


No monitoring of the waterNo monitoring of the water treatment program.

Excessive water losses resulted in icorrosion.


“Experimental” treatment program – no guidelines given to customer. No proactive

i i f li d l !monitoring of water quality and results!

8 mils/yr corrosion8 mils/yr corrosion

400,000 gal/yrWasted water


Experimental treatmentBlown boiler tube, boiler requires acid cleaning


Before You CleanBefore You Clean• Determine the cost of the “dirty” condition and

h l f h l ithe value of the cleaning• Determine the type of deposit to be cleaned and the system metallurgythe system metallurgy

• Determine spent cleaning solution disposal limitations and potential hazardsp

• Decide on a cleaning process and document procedure


Cleaning ProcessCleaning Process

• Follow the documented cleaning procedure, inFollow the documented cleaning procedure, in detail with site specific instructions

• Monitor the cleaningMonitor the cleaning• Follow disposal guidelines• Inspect the systems and document efficacy• Inspect the systems and document efficacy• Restore normal operation by flushing or drain and filland fill

• Verify and document results.


Preoperational CleaningPreoperational Cleaning

• Non‐ Galvanized Cooling Systemsg y– Use ChemTreat CT‐30 at 5 gallons per 1000

• Galvanized Towers– We recommend surfactant with a stabilized phosphate program at 20 ppm of ortho for the first 24 – 48 hours at pH 7 – 7.8. See Technical Bulletin 82.

• Stainless Food EquipmentSS16/SS16F with CL427– SS16/SS16F with CL427

• Carbon Steel Equipment– CT38


SS16 Cleaning of Stainless RetortSS16 Cleaning of Stainless Retort


CN230 Cleaning of Rotary Cookers and lBoilers

• Cleaning removes light ea g e o es gmineral scale, silica, magnesium silicate and rust.

• Removes organics, can coatings and biofilmscoatings and biofilms.

• Operate at 180°F for 3 hours.

• Phosphate free version is in development as CN232


Boiler Boil outsBoiler Boil outs

• For an improved process use the neutral pHFor an improved process use the neutral pH process at low fire, < 180 F. This process will remove oil and grease light mill scale andremove oil and grease, light mill scale and flash rust as well as pacify the boiler.


Boiler Cleaning

• Preoperational cleaning using CT38 or CT23

• Iron cleaning and passivation using CT38

• Scale Removal using CN140 followed by• Scale Removal using CN140 followed by passivation with CT38

S l R l i CN230 d CN232• Scale Removal using CN230 and CN232


Neutral pH Rust Removal and Passivation

• ChemTreat CT‐38 forChemTreat CT 38 for smaller systems

• ChemTreat CL3858, BL‐,1240 for larger systems

• See Technical Bulletin 93


Factors that Impact Cleaning using this CT‐38 process

• How dirty the system is• Temperature: Increases Rate

– Do not exceed 140°F with acidic cleaners – Do not exceed 180°F with neutral pH cleaningp g

• pH Maintain 6.5–7.2 for best results– pH<6.0 increases corrosion– pH>7 2 slows cleaningpH>7.2 slows cleaning

• Cleaning rate increases with flow– Maintain between 2–9 ft/sec

• ORP ( 50 to 600 mV)• ORP (‐50 to ‐600 mV)– A negative ORP is critical for good results– Have extra BL1240 on hand


Neutral pH Cleaning Corrosion Rates During Cleaning

C /Ad i lt• Copper/Admiralty– 1 – 4 mpy without supplemental azole– <0.5 mpy with supplemental azole

• Mild Steel– 20 – 60 mpy

• AluminumAluminum– 2 mpy

• Galvanized150– 150 mpy


How Do You Know You’re Done?How Do You Know You re Done?

• Spool pieces are cleanSpool pieces are clean• Flow is restored to design levels• Iron level/color stabilizes• Iron level/color stabilizes• pH stabilizesI l h hit i• Iron removal has hit a maximum– A multiple cleanings may be necessary in heavily fouled systems as a result of iron loadingfouled systems as a result of iron loading


Neutral pH Cleaning of a Mild Steel RetortNeutral pH Cleaning of a Mild Steel Retort


Scale Removal from Tower Fill and HeatScale Removal from Tower Fill and Heat Exchangers without Acid

• Cooling Towers– use ChemTreat CL‐401, dilute to 10 ‐50% in a garden sprayer or use as the soap in a pressurethe soap in a pressure washer. Clean long term by enhancing your

80current program at 80 ppm for 90 – 120 days


Acidic Cleaning of Cooling Towers and ChillersAcidic Cleaning of Cooling Towers and Chillers

• Long Term – Use a stabilized phosphateLong Term Use a stabilized phosphate program and control the phosphate at 15 – 25 ppm and the pH at 6.5. Even safe for galvanized.

• Short Term – Keep pH between 2 – 3 and feed in small increments over 4 – 6 hours.– ChemTreat CN‐135 best for galvanized– ChemTreat CN‐140 – Urea Hydrochloride – for mild steel, and copper. Not safe with galvanized.


Tower CleaningTower Cleaning

• Multiple OptionsMultiple Options– Surfactant and Peroxide

• CL457 at 0.5% with antifoam or

• CL427 at 4000 ppm with CL450 at 200 ppm

Baseline Post Clean

CT Capability, % 79 87

Cond Eff, % 93% 93.6%

– Chlorine Dioxide or CL3000

Halogen and Surfactant

Weight Fill, lb 81.5 47

Turb Exh Press, inHgA 3.4 3.1

MWg Gain 0.5– Halogen and Surfactant, CL450 or CT907

MWg Gain 0.5


Resin CleaningResin Cleaning

• Iron Fouling use ChemTreat CL16 at 0 5Iron Fouling use ChemTreat CL16 at 0.5 gallons per 10 cubic foot of resin.

• Biological or organic fouling use Chemtreat• Biological or organic fouling use Chemtreat CT1901 at 1 quart per cubic foot of resin with air spargingair sparging.

• Membrane cleaning – we have an entire f h li isupport group for these applications


Cleaning Techniques for Cooling Systems and...

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