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Applied Electrostatic Precipitation

K. R. Parker, ed.

1997

xvi + 520 pages

Increased awareness of the effects of atmospheric pollution and ever-tightening legislation have challenged the precipitation industry to increase performance at economical costs and operation of the precipitators has to be maintained at optimum levels to prevent penalizing consequences to plant operators. The technique of electrostatic precipitation has undergone considerable development over the past decades and is now the method of choice for limiting particulate discharges.

This volume is a good authoritative and practical guide for the industry specialist with contributions by leading experts in the field of electrostatic precipitation. Even the non-specialist will find this worthwhile as the basic theories of precipitation from both fluid and electrodynamic views are clearly presented.It also includes practical designs and gaseous and particulate features which impact precipitator performance. Future developments of precipitators are covered for the designer and developer. This mammoth compendium is a must have for the industry specialists to keep updated on the field.

Contents

Why an electrostatic precipitator?

K.R. PARKER
Introduction
Control system characteristics
Control operating principles
Inertial separation
Wet scrubbers
Fabric filter
Electrostatic precipitation
Summary of control system properties

Milestones in the history of precipitation

K.R. PARKER
Precipitator installations
Early investigations and developments
Full-scale precipitator developments
Development of electrical supplies
Rectifier types
Primary control systems
Automatic control systems
References

Basic and theoretical operation of ESPs

C. RIEHLE
General remarks
Ion production
Principles
Corona initiation field strength
Corona onset voltage
Current-voltage relationship
Electrical field distribution
Particle charging
Charging process
Cochet's charging model
Time dependence and saturation charge
Particle migration
Equation of motion
Theoretical migration velocity
Measuring and modelling particle separation
Grade efficiency and total efficiency
Laminar model
Deutsch model
Flow field and particle trajectories
Diffusivity models
Deposition
Removal
References

Mechanical design considerations for dry precipitators

F. KNUTTSEN and K.R. PARKER
Introduction
Discharge electrodes
Discharge electrode mounting
Collectors
Casings
Hi gh voltage insulators
Rapping
Hoppers
Electrical clearances
References

Aerodynamic factors affecting performance

L. LIND
Introduction
Turbulence and secondary flow
Historical resume
Turbulence
Secondary flow
Numerical flow model
Gas velocity
Gas distribution
Standards
Residence time
Space charge
Re-entrainment
Erosion
Sneakage and sweepage
Optimal distribution
Model testing
Computational fluid dynamics
Field testing
Dust build-up and wear
References

The physical and chemical properties of particles and their effect on performance

K. PORLE and K.R. PARKER
Particle size and shape
Particle sizing
Particle shape and structure
Agglomeration
Cohesivity
Particle electrical resistivity
Chemical compositon and reactivity
References

Performance design considerations

C. COTTINGHAM
Introduction
What are we trying to achieve? Assessment of the process
Typical assessment
Plate spacing
Configuring the ESP
Conclusions
References

Electrical operation of precipitators

V. REYES
Introduction
Precipitator performance and electrical energization
Examples
Corona suppression and space charge effects
Electrical characteristics with air load
Characteristics with dust load
High tension sectionalization
Traditional DC energization
Basic principles
High voltage power supply ratings
Influence of the linear inductor
Intermittent energization
Basic principles
Comparison with traditional DC energization
Collection efficiency
Automatic voltage control and instrumentation
Introduction
Instrumentation
Basic control principles
Spark detection and voltage recovery
Back-corona detection and corona power control
Pulse energization
Introduction
Electrical configuration
Main features of pulse energization
Power consumption
Collection efficiency
Applications
Summary
Supervisory computer control
Stand-alone computer
Supervisory computer control via a gateway unit
Advanced control functions
Appendix
References

Precipitator sizing methods

C. PAULSON
Theoretical considerations
Basic dust-collection equation for gas in a duct
Electrostatic precipitation
Improvement of the Deutsch equation
Factors affecting electrostatic precipitation
Practical considerations
Interpretation of test results
Precipitator modelling
Mathematical modelling
Practical testing
References

Models of electrostatic precipitators

M. REA
Basic concept
The Deutsch equation
Charging of particles and the modified Deutsch equation
The modern approach to computer modelling
Early models
Model by Canadas et al.
Modelling at Padova university

Sampling and analysis for particles and heavy metals in gas streams

G.B. NICHOLS and E.B. DISMUKES
Sampling and analysis
Heavy metals
General considerations
Sampling methods for multiple types of heavy metals
Sampling methods for mercury alone
Metal analysis in the laboratory
Prospects for real-time monitoring
References

The commissioning of electrostatic precipitators

D.A. STYLER and J.C. WESTBURY
Introduction
Mechanical commissioning
Post construction stage
Cold commissioning
Hot commissioning
Electrical commissioning
An overview
Managers and commissioning
Familiarity revisited
The programme ­ who writes the programme and when?
Monitoring
Process commissioning
Hot commissioning
Back to the real world!

Dry type precipitator applications

K. PORLE and K.R. PARKER
Introduction
Power generation industry
Bituminous coals
Anthracite coals
Subbituminous coals
Brown coals
Lignites
Oil-based fuels
The cement industry
Wet process manufacture
Semi-wet processing
Dry process production plant
Alkali bypass plant
Clinker cooler precipitators
Cement mill precipitators
General steam-raising plant
Moving grate combustors (chain grate, reciprocating and cyclic beds)
Fluidised bed units
Biomass-fired steam-raising plants
Wood chip combustion
Chicken litter, etc.
Municipal wastes
Iron and steel works
Sinter plants
Pelletising plants
Steel making
Operations involving the casting of hot metal
Non-ferrous industries
Copper and nickel recovery
Aluminium smelting
Paper and pulp industry
Bark firing
Cellulose pulp production
Lime sludge burning
Magnesium sulphate burning
Conclusions
References

The wet electrostatic precipitator: design and applications

K.R. PARKER
Introduction
Design considerations
Dust deposition and removal
Discharge electrodes
High tension insulators
Casing/hopper design
Water treatment
Materials of construction
Electrical energisation
Typical applications of wet precipitators
Applications in the iron and steel making fields
Applications in the chemical industries
Applications following acid gas scrubbers
Incineration-type processes
HAC discharges
Glass manufacturing
Other applications

The mist precipitator: design and applications

K.R. PARKER
Introduction
Applications of mist precipitators
Collection of sulphuric acid mist
Gas detarring
Collection of radioactive particles
Other mist precipitator applications
Conclusions

Upgrading of existing precipitator efficiencies

K.R. PARKER and H. KRIUMONT

Modifications/changes to existing plant

Assessment of required performance improvement
Performance improvement modification options
Alternative solutions
Electrical
Mechanical changes

Precipitator improvements achieved by changing the electrical resistivity of the particulates

Change of temperature/relative humidity of the gases
Flue gas additives to improve performance

Theory, principles of operation, equipment and applications of flue gas conditioning (FGC)

Introduction
Electrical resistivity
Prediction of fly ash resistivity
Resistivity effects in ESPs
Flue gas conditioning
Conditioning by sulfur trioxide
Ammonia conditioning
Dual flue gas conditioning
Balance of plant impact
Flue gas conditioning equipment
SO3, FGC systems
Ammonia FGC systems ­ design features
ESP power consumption
Mixing requirements
Application of flue gas conditioning in converting hot-side fly ash precipitators to cold-side operation
Introduction
Flue gas conditioning
Installation design
FGC operation
Economics
Conclusions
FGC systems ­ optimization
General
Theoretical approach
Procedural approach
Statistical approach
Rapper adjustments
Data collection
Conclusions
References

Possible future developments in the field of electrostatic precipitation

K.R. PARKER, C. RIEHLE and H. KRIGMONT

Electrical developments

High frequency power conversion or switched mode power supplies
Nanosecond pulse operation and acid gas control

Use of natural sulphur dioxide as a feed stock for flue gas conditioning systems: flue gas conditioning today and tomorrow

Background
'Native' or 'internal' feed stock FGC technologies
'Slip-stream' FGC systems
In-duct FGC systems
In-situ gas conditioning (IGC) approach
Variable exposed area IGC system
Variable catalyst temperature IGC system
Variable flow lGC system
Catalyst selection

High temperature/high pressure precipitators for advanced power generation systems

Fundamentals
Voltage and current
Particle charging
Particle migration
Grade efficiency
Open questions
Electrical resistivity
Mechanical stability of material
Rapping
Electrical insulation
Emptying of hoppers
Electrical power consumption
Symbols
References

Computer sizing of precipitators