CCGT/HRSG WATER CHEMISTRY COURSE OUTLINE

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Alaina Hopkins
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1 1.0 WATER CHEMISTRY CONCEPTS 1.1 The Atom, Atomic Structure, and Chemical Periodicity Introduction The Atom and Atomic Structure Atomic Structure The Electron Structure of Atoms Elements, Chemical Symbols, and Avogadro s Number Symbols for Elements Atomic Number Atomic Weight Avogadro s Number Isotopes The Periodic Table Chemical Periodicity The Periodic Table of the Elements Organization of the Periodic Table Electron Structure and Chemical Properties Classes of Elements in The Periodic Table Metals Nonmetals Metalloids Noble Gases 1.2 Compounds, Compound Formation, and Chemical Reactions Introduction Compound Formation and the Chemical Bond Stable Electron Structure: The Octet Rule Valence: Combining Power of Elements Chemical Formulas for Representing Compounds The Ionic Bond Ionization and Ions Properties of Ionic Compounds The Covalent Bond Molecules Radicals Chemical Nomenclature and Formulas Chemical Reactions and Stoichiometric Calculations Chemical Reactions Reason for Chemical Reactions Energy Changes Associated with Chemical Reactions Chemical Reactions versus Physical Changes Conservation of Mass in Chemical Reactions Conservation of Atoms in Chemical Reactions Chemical Equations 1

2 1.2.4 Stoichiometric Calculations The Mole and Weight Relationship in Chemical Reactions Molecular Weights and the Law of Definite Composition The Mole 1.3 Summary 2.0 WATER CHEMISTRY CONCEPTS - CONTINUED 2.1 Solutions in Power Plant Chemistry Introductions Solutions: Solvent and Solutes Definition of a Solution Dispersions and Suspensions Polar and Non-Polar Solvents Water as a Solvent Ionic Solutions in Water Solubility Effect of Temperature and Pressure on Solubility Concentration of Solutions General Terms for Expressing Concentration Percent by Weight Density, Specific Gravity, and the Baume` Scale Percent by Volume Parts per Million (ppm) and Parts per Billion(ppb) Molar and Molal Solutions Normal Solutions and Equivalent Weights Preparing Solutions Gas Concentrations 2.2 ph and Conductivity of Solutions Introductions Acids and Bases Properties of Acids and the Hydronium Ion Properties of Bases and the Hydroxide Ion Neutralization Reactions and Salt Formation The Definition of ph and the ph Scale The Ionization of Water The ph Scale and Other Logarithmic Functions The Effect of Temperature on ph Conductivity Equivalent Conductance Solvent Effects: The Conductivity of Pure Water Temperature Effects on Conductivity 2

3 Power Plant Conductivity Measurements Cation Conductivity 2.3 Summary 3.0 CORROSION AND CORROSION CONTROL Introduction 3.1 Overview of Corrosion Mechanisms and Types of Corrosion Uniform Corrosion Localized Corrosion: Macroscopic Attack Galvanic Corrosion Erosion Corrosion Flow Accelerated Corrosion (FAC) Crevice Corrosion Pitting Corrosion Exfoliation Selective Leaching Localized Corrosion: Microscopic Attack Intergranular Corrosion Stress-Corrosion Cracking Corrosion Resistant Alloys Used in Plants The Stainless Steels Copper Based Alloys Specialty Materials 3.2 Chemistry Aspects of Corrosion Oxidation and Reduction Passivity Corrosion of Iron in High Temperature Water Oxygenated Treatment Effects of ph Effect of Solution Flow Rate Effect of Dissolved Oxygen Temperature Effects Specific Chemical Effects Chemisorption Chloride Stress-Corrosion Cracking Concentrated Caustic Cracking Underdeposit Corrosion 3.3 Summary 3

4 4.0 CORROSION CONTROL 4.1 System Chemistry Control Specifications and Guidelines Elements of Chemistry Control Programs Phosphate Chemistry Control Coordinated Phosphate - ph Control Congruent Phosphate Control Sodium Hydroxide Control Oxygen Treatment (OT) Control Equilibrium Phosphate Treatment (EPT) Correcting Na/PO 4 Ratios for Ammonia-Induced Errors Phosphate Hideout All-Volatile Chemistry Control Oxygen Control Impurity Control Impact of System Materials on Chemistry Controls Effect of Condenser Tube Material Effect of Feedwater Heater Tube Material Effect of Boiler Tube Material Effect on Turbine Blading Chemistry Control for Various Modes of Plant Operation Base Load Operations Cycling Operations Effect on Feedwater Cycle Chemistry Effect on Boiler Water Chemistry Hot Start-up Cold Start-up Wet Lay-up Dry Lay-up System Chemistry Action Level Concept Action Levels Defined Response Guidelines for Out-of-Normal Chemistry System Chemistry Specifications Makeup System Condensate Chemistry Feedwater Chemistry Boiler Drum Water Silica Control in Boiler Water and Steam Main Steam Chemistry Closed Cooling Water Systems Circulating Water Systems Deposit Control ph Control 4

5 Biocide Treatment Corrective Action 4.2 Summary 5.0 HRSG INTRODUCTION 5.1 Introduction 5.2 HRSG Designs Pre Combined-Cycle Combined Cycle Operation Future Design Applications 6.0 HRSG DESIGNS AND COMPONENT INTEGRATION 6.1 Introduction 6.2 Economizer 6.3 Evaporators 6.4 Steam Drums 6.5 Superheater and Reheater 7.0 COMBINED CYCLE COMPONENTS AND CONSIDERATIONS 7.1 Introduction 7.2 Steam Turbine 7.3 Condenser 7.4 Monitoring Points and Control Rationale 7.5 Control Limits and Action Levels 8.0 ENVIRONMENTAL ISSUES 8.1 Introduction 8.2 NOx Production 8.3 NOx Control 8.4 Water Production 9.0 WATER TREATMENT METHODS AND ION EXCHANGE THEORY 9.1 Introduction 9.2 Terms Used in Water Treatment ph Conductivity Free Mineral Acidity Alkalinity Hardness Carbonate Chemistry Langelier Index and Ryzner Index 9.3 Clarification and Filtration in Water Treatment Introduction 5

6 9.3.2 Clarifiers Applications Principle of Operation Conditions for Successful Coagulation-Flocculation Coagulant Chemicals Inorganic Coagulants Polymers and Polyelectrolytes Sedimentation, Blowdown, and Backflush Out-of-Specification Conditions Filtration Basis for Filtration Bed Filters Types of Bed Filters Gravity Filters Pressure Filters Upflow Filters Out-of-Specification Conditions 9.4 Reverse Osmosis Reverse Osmosis Water Pretreatment Introduction Reverse Osmosis Process Reverse Process Application Membrane Selection and Construction Cellulose Acetate Membranes Polyamide Membranes Membrane Construction RO Troubleshooting Particulate Fouling Organic Fouling Sealing Membrane Chemical Attack 9.5 Ion Exchange Introduction The Ion Exchange Process Ion Exchange Resins in Water Treatment Cations and Exchange on Resins Anions and Exchange on Resins Classes of Ion Exchange Resins and Their Structure Classes of Resins Strong Acid Cation Resins Weak Acid Cation Resins Strong Base Anion Resins Weak Base Anion Resins Gel and Macroporous Resins 6

7 9.5.4 The Ion Exchange Capacity of Resins Ion Exchange Capability Total Exchange Capacity of Resins Operating Capacity Column Capacity 9.55 Ion Exchange Equilibria Reversible Nature of Ion Exchange The Affinity Coefficient Factors Affecting Ion Exchange Equilibria Ion Exchange Kinetics Exchange Rates Film Diffusion Rate Particle Diffusion Rates Factors which Affect Ion Exchange Kinetics Application Rates Temperature Organic Fouling Resin Particle Size Deep Bed Ion Exchanger Types Cation Resin Units Anion Resin Units Mixed Bed Units Resin Exhaustion and Regeneration Resin Exhaustion Resin Regeneration 9.6 Summary 10. CHEMISTRY CONTROL SURVEILLANCE AND ANALYTICAL METHODS Introduction 10.1 Sampling Criteria for Sampling Frequency General Considerations in Sampling Sample Flow Rate Sample Conditioning (Temperature or Cation Exchange Processing) Dead Legs Sampling to Eliminate Atmospheric Gases Density Corrections Sample Containers and Sample Preservation Purging Volumes Sample Temperature Adjustments Grab versus Composite or Inline Samples Steam Sampling 7

8 10.2 Common Power Plant Analyses ph Measurements Specific Conductance Measurements Cation Conductivity Versus Specific Conductivity Oxygen Analyses The Indigo Carmine Dissolved Oxygen Method Winkler Dissolved Oxygen Method Dissolved Oxygen by Chemets Biological Oxygen Demand (BOD) Spectrophotometric Analyses Chloride Determination Spectrophotometric Chloride Determination Mercuric Nitrate Titrimetric Chloride Method Nephelometric Chloride Ion Determination Analytical Measurement Limitations Laboratory Measurement Limitations Limitations of Inline Process Measurements 10.3 Inline Monitoring Conductivity Monitors Specific Conductivity Cation Conductivity Temperature Correction Calibration of Conductivity Monitors Maintenance of Conductivity Instrumentation ph Monitors Temperature Corrections Standardization Maintenance of ph Instrumentation On-line Sodium Analyzers Standardizing Sodium Analyzers Maintenance of Sodium Inline Analyzers Dissolved Oxygen Analyzers Standardizing On-line Oxygen Analyzers Maintenance of On-line Oxygen Analyzers Silica Analyzers Standardization of Inline Silica Analyzers Maintenance of Silica Analyzers Recorders Documentation of Calibration and Maintenance 10.4 Summary 8

9 11.0 LABORATORY ANALYSIS 11.1 Introduction ph Meters Standardization of Laboratory ph Meters Maintenance of Laboratory ph Meters Conductivity Instrumentation Calibration of Laboratory Conductivity Instrumentation Maintenance of Laboratory Conductivity Instrumentation Selective Ion Electrodes (SIEs) Spectrophotometric Analysis Amperometric Titrator Operation and Maintenance Analytical Balance Calibration and Maintenance Documentation of Calibration and Maintenance 11.2 Laboratory Quality Assurance/Quality Control Purpose of Laboratory Quality Control Programs Reagent and Standard Solution Controls Dry Chemicals, Acids, and Solvents Purchased Reagents and Solutions Prepared Reagents Reagent Standardization Purchased Standards Prepared Standards Special Precautions for Trace Level Analyses Facilities Reagents Sample and Standard Handling Control of Analytical Performance Purpose of Control Charts Preparation of Spiked Samples Calculation of Percent Recovery Construction of Accuracy Control Charts Duplicate Sample Analysis Calculation of Precision Construction of Precision Control Charts Use of Completed Control Charts Blind Sample Analysis 11.3 Summary 12.0 DATA MANAGEMENT AND EVALUATION Introduction 12.1 Laboratory Data Logging Recording Raw Laboratory Data Reporting of Analytical Data 9

10 Daily Chemistry Logs Instrument Logs 12.2 Data Review and Evaluations Use of Acceptance Criteria Awareness of Plant Activities Correlation of Interrelated Parameters Trend Plotting of Critical Parameters 12.3 Response to Abnormal Chemistry Conditions Verification of Analytical Results Initiation of Corrective Action Documentation of Corrective Action 12.4 Summary 13.0 FOSSIL BOILER CHEMICAL CLEANING 13.1 Introduction 13.2 Boiler Deposits Condenser Tube Leaks Air Inleakage Ion Exchangers 13.3 Materials of Construction 13.4 Summary 14.0 CHEMICAL CLEANING SOLUTIONS 14.1 Introduction to Chemical Cleaning Solutions 14.2 Chemical Cleaning Solutions Mineral Acid Solvents Hydrochloric Acid Sulfuric Acid Phosphoric Acid Sulfamic Acid Organic Solvents Hydroxyacetic-Formic Acid Mono-Ammonium Citrate Ethylenediaminetetraacetic Acid Chelating Agents Other Solvents and Cleaning Solutions Ammoniated Bromate Ammonium Persulfate Ammonium Bicarbonate Ethylenediamine/Salicylic Acid Alkaline Permanganate Solution Alkaline Detergent Solutions Physical Factors in the Cleaning Process Circulation 10

11 Contact Time Concentration Chemical Cleaning Solvent Additives Surfactants Inhibitors Complexors Rinsing, Neutralizing, and Passivating Solutions 14.3 Summary 15.0 FACTORS CONTROLLING CHEMICAL CLEANING 15.1 Safety 15.2 Post-Cleaning Inspection 15.3 Waste Treatment Disposal Options 15.4 Summary 16.0 CHEMICAL CLEANING PROCESS 16.1 Isolation of the System Flushing and Debris Removal Hydrostatic Testing and Leak Detection Superheater and Economizer Flushings Preheating Temperature Control Solvent Injection and Leak Detection Monitoring of the Cleaning Process Solvent Circulation Control Draining and/or Displacement of Solvent Rinsing, Monitoring and Flushing After Solvent Removal Neutralization of Residual Solvent Passivation of Cleaned Surfaces Inspection of the Cleaned System Unit Lay-Up Safety Procedures 16.2 Summary 17.0 FREQUENCY OF CHEMICAL CLEANING 17.1 Visual Inspection 17.2 Non-Destructive Inspections The Turner Tube Scale Thickness Indicator Adaptation of the Turner Indicator Fiberscope or Boroscope Analysis Chordal Thermocouples Other NDI Methods 11

12 The Limitation of NDI 17.3 Physical Examination Selection of Location Method of Tube Removal Tube Deposit Analysis Determination of Deposit Wet Chemistry X-Ray Diffraction 17.4 Cleaning Frequency 17.5 Solvent Selection 17.6 Summary 12

Glossary of Common Laboratory Terms

Glossary of Common Laboratory Terms Accuracy A measure of how close a measured value is to the true value. Assessed by means of percent recovery of spikes and standards. Aerobic Atmospheric or dissolved oxygen is available. Aliquot A measured