Overview The value of condensate Condensate corrosion Condensate treatment Condensate monitoring, sampling and control

Condensate System

Condensate Treatment Technology is the Implementation of an Integrated Chemical, Mechanical and Monitoring Program to Derive Significant Operating Cost Savings in Plant Operation

The Value of Returning Condensate Condensate is Hot Water! Most Industrial Condensate Systems are pressurized Utilities and some process systems are under vacuum Condensate is (reasonably) Pure Water! Low conductivity water replaces additional demineralized makeup water for boiler feedwater Replaces softened water and allows boiler to operate at higher cycles of concentration

Typical Condensate ReturnIndustry Chemical Cogen Paper Petrochemical Power Refining Steel Typical % Return 30-60 20-80 40-65 65-85 95-99 10-60 5-50

The Risks of Returning Condensate Process Contamination Oil Process Constituents Raw Water Constituents Oxygen Hardness Corrosion Products Iron Copper

Why is Condensate Treatment Needed?Condensate Treatment is the Battle Against Three Dissolved Gases: CO2 O2 NH3

Carbon Dioxide SourcesBreakdown of feedwater alkalinity 2 HCO3 Bicarbonate heat Carbonate heat

CO3 -2 + H 2O + CO 2Water

Carbon Dioxide

CO3 -2 + H2OCarbonate

Water

2OH - + CO 2Hydroxide

Carbon Dioxide

Air inleakage Breakdown of organic compounds present in the feedwater

Where CO2 Corrosion Occurs

CO2(g) + H2O(g) --> No Reaction CO2(g) + H2O(l) --> H2CO3(l) (carbonic acid) Then, H2CO3(l) H+ + HCO3-

Wastage Caused by CO2

Softened Water used for Boiler Makeup produces a considerable CO2 concentration in the condensate. Consider revising the external treatment system to reduce the CO2 loading. Demineralized Water greatly reduces the CO2 loading in the system, but there is still sufficient present to depress condensate pH and still require treatment.

Feedwater Alkalinity Reduction To Control CO2 Generation Lime softening Dealkalization Degasification Demineralization Increased condensate return

Oxygen Corrosion in Condensate

Sources of Oxygen in Condensate Systems Systems under vacuum Intrusion into Batch Processes In and out of Service Equipment Leakage past Pump Seals Service water used to Quench Alternate heating/cooling cycles

Mechanical Corrections to Oxygen IntrusionCauses of O2 Entry Into Vacuum Systems Out-of-Service Systems Open Receivers Pump Seal Leakage Quench Water Alternate Heating/Cooling Means of Detection Check Gauges Test at Start-up Identify Test In-Service Test/Observe Identify Remedy Repair Leaks Dump Condensate Repipe Below Liquid Level Repack, or Install New Seals Remove Source Dump Condensate

Ammonia is the Third Dissolved Gas to be Considered Ammonia only attacks copper alloys Sources of Ammonia Ammonia added as a treatment Amine-based treatment decomposition Thermal decomposition of hydrazine Nitrogen containing organics present in make water

Mechanism of Ammonia Attack Ammonia Dissolution in Liquid Phase NH3(g) + H2O(l) --> NH4OH Ammonia Ionization NH4OH NH4+ + OHCopper/Ammonia Complexation Cu+2 + 6NH4+ --> Cu(NH4)6

AmmoniaDissolved oxygen ppb 0 to 20 20 to 50 >50 Maximum allowable ammonia, ppm 0.5 0.3 Any level may be a problem

Remedies for Ammonia Attack Alloy Selection (Youll never see copper piping in an ammonia plant) Consider a hydrazine substitute Evaluate neutralizing amine selection Sewer contaminated condensate (i.e. air injector drains) There is no treatment for ammonia attack

System SurveyS te a m / o n d e n s aS y ste m s C a n B e E x te n s iv e C teM a ke - up Pr o ce s s

x R e b o iler s d an x K et tl es e ttl

Id e n tify E q u ip m en t h e at ex c h a n g ers a n d re a cto r s

P r o ce s s

P r o ce s s Low p re s su re st e a m B low d ow n fl a s h t a nk F l a sh t a nk C o nd e n s a te R e c e iv e r

x C o n d en s e rs se x Tank x S t ea m x F la sh

h ea ter s tr ap s ta n k s a n d re ce ive rs ta

A complete system survey is the key to any effective treatment strategy The survey defines system needs and limitations

Steam Traps

Condensate Treatment

Condensate Treatment Alternatives Neutralizing Amines Distribute throughout systems Neutralize CO2 Elevate condensate pH Filming Agents Both amines and non-amines are used Create a barrier between condensate and piping Scavenger/Passivating Agents Primarily condition metal surfaces

Neutralizing Amines Neutralizing amines are the most universally used chemical treaments to prevent CO2 corrosion Neutralizing amines are organic compounds with an amino functionality attached (-NH2; NHR; -NR2) The organic group may be cyclic, a straight chain or a branched chain.

Why Amines are So Popular Direct Neutralization of CO2 Direct elevation of pH Easy to feed Easy to Control Many options available Few Side Effects Compatible with other system treatments Treatment Recycles Blends Available

Weaknesses of Amines Selection requires system knowledge Presumed performance doesnt always occur Can be expensive if CO2 loading is high No impact on oxygen contamination Some systems cannot tolerate nitrogen Adds conductivity to condensate

Amine Selection in a Simple SystemAmine Volatility is not as big an issue when condensation is one and done External Treatment System

CondenserEconomizer Makeup Water Boiler Deaerating Heater Boiler Feedwater Pump

Steam Turbine

Superheater

A Typical Paper Machine Dryer Configuration Represents a Complex Condensate System

Neutralizing Amine Selection Criteria Need for Volatility Amount of CO2 Expected FDA Regulations Applicable? Pressure of Steam System Process Considerations Direct Contact with Process? Steam used for Humidification

Neutralizing Amine Operating Mechanism Volatility - As measured by Distribution Ratio at the pressure of two phase conditions Neutralizing Capacity - As determined by the molecular weight of the amine molecules present pH Elevation - As determined by the basicity constant of the molecules present

The Importance of Volatility Volatility positions the amines in complex systems Amine volatility is always compared to CO2 Volatility is measured by V/L Ratio or Distribution Ratio Volatility is not as important in simple systems

Amine Volatility is Very Temperature & Pressure Dependent

Amine Volatility vs. PressureName 0 CO 2 NH3 MEA A min o m e th y lp r o p a n o l Mo r p h o lin e MO PA DEA E DMA IP Cy c lo h e x y la m in e 4 .0 3 .0 ** Ex p e r ime n ta l B o ile r Re s u lts 0 .4 0 0 .4 4 3 V /L R a i t o v s B o i l e r p r e ssu r e ( p si g ) ** 50 4 .8 150 8 .5 6 .7 0 .1 1 0 .6 5 0 .9 9 2 .1 5 .8 7 .3 9 .0 450 8 .5 7 .0 0 .1 7 0 .6 5 1 .1 0 2 .0 6 .3 4 .8 9 .4 600 1 5 .8 5 .0 0 .2 4 0 .7 7 1 .2 2 2 .3 5 .2 4 .9 8 .2 900 >9 9 .0 4 .3 0 .2 5 0 .8 6 1 .2 2 2 .0 4 .5 4 .2 7 .0

Using Concept of Volatility Evaluate System to determine if volatility matters Amine blends provide for most comprehensive coverage Look for places of steam venting (flashed steam), and pick amine to avoid loss Focus on amines in locations of maximum condensate return

Neutralizing Amines Neutralizing capacity determines amount of CO2 (actually carbonic acid) that the amine can counteract Neutralizing capacity is specified by the molecular weight of the amine

Molecular Weight of AminesAmine Morpholine Cyclohexylamine MOPA DEAE MEA MW 87 99 89 119 61

Corrosion of Carbon Steel and Copper Depends on pH of WaterAfter neutralization, the final function of the amine is to boost condensate pH into the range where total metal solubility is minimized. The measure of an amines capability to boost pH is specified by its basicity constant.PH Control Ranges Mixed iron-copper metallurgy Ferrous Metallurgy Typical 8.5-9.2 8.5-9.5 For Neutralizing Amines Preferred 8.8-9.2 9.0-9.5

Amine IonizationR-NH2 RNH3+ + OHAmines that stay in the R-NH2 form contribute little to pH elevation. Amines that ionize more completely are more cost-effective.

Ionization Properties of Different Amines, NH3 and CO 2Name pKa* CO2 4.3 NH3 9.3 Monoethanolamine, MEA or EA Aminomethylpropanol, AMP Morpholine 8.4 Methoxypropylamine, MOPA Diethylaminoethanol, DEAE Cyclohexylamine 10.6 Dimethylamino-2-propanol, DMAIP Diethanolamine, DEA 8.9 Dimethylpropylamine, DMPA Dimethylaminoethanol, DMAE 9.5 9.5 10.1 9.6 9.6 10.7 9.6

* pKa indicates base strength of the amine. The higher the pKa the stronger the base.

Amine Neutralizing Ability11

9 pH 7 5 0.0 0.5 1.0 1.5 2.0 2.5 ppm Amine / ppm CO2 Morpholine 3.0 3.5 4.0

Cyclohexylamine

Diethylaminoethanol

Regulatory Issues

FDA Applications Amines cannot be used to treat steam which could contact milk or milk products

Cyclohexylamine Diethylaminoethanol

10 ppm 15 ppm 10 ppm 3 ppm

q

Only four amines are FDA approved Steam concentrations are limited

Morpholine Octadecylamine

q

OSHA* RestrictionsOSHA PEL Limits

Morpholine Diethylaminoethanol Cyclohexylamine

20 ppm 10 ppm 10 ppm

Establishes the concentration of amines in air to which a healthy worker could be exposed for an eight hour period Known as the PEL (Permissible Exposure Limit)

* Occupational Safety and Health Administration

Summary of Neutralizing Amine Use Determine the regulatory limitations Determine type of system - single pressure(simple) or multiple flash (complex) Select Amine Volatility to get Treatment where needed Ascertain amount of CO2 to justify selection based on Neutralization Capacity Select condensate pH control range on basicity of amines in use Satellite fed maybe necessary Monitor throughout the system