condensate part 2 notes

Filming AminesFilming Amines

• High CO2 loading makes neutralizing amines costly

• Film barrier provides some protection against oxygen corrosion

• Filming Amines may protect against erosion

• Filming Amines may improve heat transfer

Why Use a Filming Amine?Why Use a Filming Amine?

• Hard to Feed

• Little Selection Available

• Possible Fouling

• Program must start slowly

• Not completely effective against oxygen

Why Not Use a Filming Amine?Why Not Use a Filming Amine?

Protective filming amine layer

Metallic wall

O2 CO2

CO2

O2

O2

O2

O2

O2

O2

CO2

CO2

CO2

CONDENSATE

O2

O2

O2

O2CO2

CO2

CO2

CO2

O2

Filming AminesFilming Amines

Primary Amines

RNH2

Secondary Amines

(R)2NH

Tertiary Amines

(R)3N

Different Filming MoleculesDifferent Filming Molecules

• May need to be diluted with Condensate

prior to feeding

• Must be Fed to Steam Header

• Must be Fed through Injection Nozzle

• Feed Pump Interlocked to Steam Flow Meter

Filming Amines Feeding Requirements

Filming Amines Feeding Requirements

Factors that Break Down Filming Amines

– Hard Water Contamination

– pH too low (< 6.5)

– pH too high (8.5)

– Organic Contamination

Filming Amines Fail When The Film Breaks Down

Filming Amines Fail When The Film Breaks Down

Advanced Condensate Treatment

“The World’s Most InnovativeCorrosion Inhibitor”

NALCO ACTNALCO ACT

• ACT is an Ondeo Nalco patented condensate treatment technology

• Its a blend of emulsifiers used in the Food Industry (contains no amines or other nitrogen- containing compounds)

• Provides a comparable barrier to the historically used amines; pH control range 5.5 to 7.5

• Much reduced fouling potential

• Fully approved by regulatory agencies

• Effective in inhibiting CO2 and O2 corrosion

ACT: Something New in Filming Agents

ACT: Something New in Filming Agents

• Steam Header Feed

• Stainless steel slotted retractable quill injector (P4634 and P4694)

• Quill orientation is important

• Fed neat or in dilution

• Should be fed continuous

• Max pressure 600 psig (41 bar)

• Max Temp 486oF (252oC)

ACT Feeding RequirementsACT Feeding Requirements

• Useful when CO2 loading prevents economic application of neutralizing amines

• Are effective in inhibiting oxygen corrosion

• Make the commitment to feed properly

• May have merit to prevent erosion in certain applications

• Poor reputation due to fouling potential

Summary of Condensate Filming Treatments

Summary of Condensate Filming Treatments

• Given the lack of effectiveness of other treatments on oxygen, the application of some feedwater oxygen scavenging technology in the condensate area is a good fit

• After taking all possible mechanical corrective measures, the application of a chemical treatment can be effective

Oxygen Scavenging - Metal Passivation in Condensate Treatment

Oxygen Scavenging - Metal Passivation in Condensate Treatment

• Hydrazine

• Carbohydrazide

• DEHA

• Hydroquinone

Molecules AvailableMolecules Available

• “Conditioning” of metal surface to prevent

corrosion, even if oxygen is present

• Conversion of ferric oxidation state to

reduced oxide form i.e. Fe3O4 (magnetite)

• Direct removal of oxygen

Operating Mechanism of Scavenger / Passivator

Operating Mechanism of Scavenger / Passivator

• After all steps taken to limit oxygen entry• Cost analysis between condensate dumping and

treatment application• Trial conducted on small part of system, monitoring

iron throw before and after treatment use• Can be beneficial when electromagnetic polishing is

in use

When a Scavenger/PassivatorShould be Applied

When a Scavenger/PassivatorShould be Applied

• Supplemental feed to steam system is usually required

• Condensate Systems are dymanic and may not operate at trial conditions

• Oxygen ingress may be sporadic

• Results may not meet expectation

Problems with PassivationProblems with Passivation

• Most applicable in batch processes, where known oxygen intrusion will occur

• Feed point selection is critical to get coverage/performance

• Good monitoring required to justify

• May avoid capital expense of supplemental condensate purification or excessive dumping

Summary of Scavenging / Passivation Treatment

Summary of Scavenging / Passivation Treatment

TYPE OF DEVICE OPERATING

MECHANISM

STRENGTH WEAKNESS

A) SODIUM-CYCLE

CONDENSATE

POLISHER

B) AMINE CYCLE

ION

EXCHANGE

ION

EXCHANGE

VERSATILE

PREVENT SODIUM

CONTAMINATION

ALTERS BOILER CHEMISTRY

COST

MIXED BED

CONDENSATE

POLISHER

ION

EXCHANGE

EXCELLENT

EFFLUENT

QUALITY

LIMITED TO 120oF (49oC)

CARTRIDGE

FILTRATION

FILTRATION INEXPENSIVE HIGH CHANGE-OUT RATE

WITH HIGH LOADING

PRECOAT

FILTRATION

FILTRATION COST-EFFECTIVE SUBJECT TO MECHANICAL

FAILURE

ELECTROMAGNETIC

FILTRATION

FILTRATION EXCELLENT

EFFLUENT

QUALITY

COST, UNCERTAINTY OF

COPPER REMOVAL

Supplemental / Mechanical Condensate Purification

Supplemental / Mechanical Condensate Purification

• Hard to justify in normal operation, usually installed as part of an expansion or upgrade

• May require chemical treatment for optimum effectiveness

• May impact boiler water quality

• Many existing systems are poorly maintained, not that effective

Comments on Condensate Purification

Comments on Condensate Purification

Condensate Sampling and Monitoring

Condensate Sampling and Monitoring

• Critical equipment and/or largest steam users

• Composite streams prior to receivers or flash tanks

• Known problem areas

• Return condensate streams

Where Do You Sample?Where Do You Sample?

• Cooled to less than 90oF (32oC)

• Sample flow throttled at outlet only

• Stainless steel sample lines

• Continuous flow

• Adequate velocity

• Throttle valve installed outlet side of cooler

Sampling RequirementsSampling Requirements

Sample line

Sample tap

Sample tap

1/2 in. dam. SS gate valve

1/4 in SS sample line

Gate valve

Sample cooler

45oF

Top

Throttle valve

Sampling Horizontal LinesSampling Horizontal Lines

Monitoring Techniques Include:• pH• Iron Measurement• Filtration Testing• Conductivity• Turbidity• Corrosion Coupons• Electrochemical Corrosion Monitoring

Condensate monitoring is very demanding

Condensate monitoring is very demanding

• Sample temperature is critical

• Should use dedicated pH meter and electrode

• Sample collection isn’t as difficult as might be thought

• Meter calibration is required

Measuring Condensate pHCorrectly Provides Powerful Data

Measuring Condensate pHCorrectly Provides Powerful Data

• Many analytical methods available

– AA

– ICP

– Photometric Wet Chemistry

• Must employ a digestion step

• Sample collection is complex, since we are dealing with particles

Iron AnalysisIron Analysis

• Standard technique is to use:

– 1 liter condensate sample

– 0.45 micron filter pore size

• Comparison charts available to quantify results

• Best when fixed atop system schematic to locate system problems

Filtration Testing of CondensateFiltration Testing of Condensate

• Depends on process– Paper mills have highly ionic process fluids– Oil/petrochemicals may not be seen

• Realize impact of treatment• Some systems use cation column to magnify presence of

ionic materials• In critical system, install automatic dump based on

conductivity meter

Conductivity as a Condensate Monitoring Tool

Conductivity as a Condensate Monitoring Tool

Automatic ConductivityMonitoring System

Automatic ConductivityMonitoring System

• Turbidity can be Correlated to Metals Concentration

• Locate close to Equipment being Monitored to cut Sample Lag Time

• Can be Incorporated with Diversion Valve

• Choose a meter that Scans the Surface of a sample

Turbidity is a Technique to Monitor Particulate Iron On-Line

Turbidity is a Technique to Monitor Particulate Iron On-Line

Example of Turbidity Diversion System

Example of Turbidity Diversion System

• Match Monitoring Technique to type of program in use

• Look for consistency - high turbidity should correlate with a highly colored Millipore

• Sampling protocol is more important for some techniques that others

• Be Creative! - Find something unique about your system

Summary of Condensate Monitoring

Summary of Condensate Monitoring

Key TakeawaysKey Takeaways

• Condensate Treatment Technology is the Implementation of an Integrated Chemical, Mechanical and Monitoring Program to Derive Significant Operating Cost Savings in Plant Operation. Recycling or returning as much steam condensate back as part of the boiler feedwater makes good business sense. It’s already been paid for, generally the quality is high purity, and it contains valuable heat content.

Key TakeawaysKey Takeaways

• Condensate corrosion is caused by the presence of dissolved carbon dioxide, oxygen and/or ammonia. The three types of condensate treatment chemistries used to inhibit these corrosive species are, neutralizing amines, filming agents and passivating oxygen scavengers.

Key TakeawaysKey Takeaways

• Neutralizing amine product selection requires that you know the plant’s regulatory limitations with respect to amine usage, and how complex the steam condensate system is that you are trying to treat. Select amine products based on their V/L ratio characteristics, basicity and where the condensate is returned from. Complex steam condensate systems may require satellite feed of amines to control pH in more remote areas.

Key TakeawaysKey Takeaways

• Filming amines and Ondeo Nalco’s non-amine ACT chemistry lay down a protective barrier to keep the corrosive species away from the metal surface. Filming agents are typically used when high CO2 loading makes neutralizing amines too costly, or when the system is experiencing dissolved oxygen problems.

Key TakeawaysKey Takeaways

• Certain passivating oxygen scavengers help reduce the amount of iron returned in the condensate. They condition the metal surface to slow down and inhibit oxygen attack. Secondly they can react with oxygen directly.

Key TakeawaysKey Takeaways

• The goal of installing sample points and monitoring a condensate system is to be able to determine how well it is being protected. They should enable you to identify where problem areas are located in the system and provide you with an effective way to rapidly trouble shoot the system when new problems arise. Things that need to be monitored include pH, iron, conductivity and dissolved oxygen.

Key TakeawaysKey Takeaways