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GC 1: Introduction to Gas Cleaning

GC 1: Introduction to Gas Cleaning
     Part 1: Introduction to Gas Cleaning
         1 OVERVIEW OF GAS CLEANING AND THE SPS GAS CLEANING MANUAL
             1.1 Introduction to Volume I
         2 GAS CLEANING THEORY
             2.1 Introduction
             2.2 Particle suspensions - definitions and classifications
                 2.2.1 Aerosols, dusts and mists
                 2.2.2 Aerosol typologies
             2.3 Particle size, shape and size distribution
                 2.3.1 Particle sizes of interest
                 2.3.2 Particle diameter and shape
                 2.3.3 Average diameters
                 2.3.4 Size distributions
             2.4 Forces on particles and particle transport mechanisms
                 2.4.1 Introduction
                 2.4.2 Fluid drag forces
                 2.4.3 Gravitational forces
                 2.4.4 Centrifugal forces
                 2.4.5 Electrostatic forces
                 2.4.6 Brownian diffusion
                 2.4.7 Thermophoresis
                 2.4.8 Diffusiophoresis
                 2.4.9 Adhesion and cohesion
             2.5 Particle capture processes
                 2.5.1 The particle equation of motion
                 2.5.2 Particle collection by submerged spheres
                 2.5.3 Collection by cylinders
                 2.5.4 Deposition from flow parallel to surfaces
                 2.5.5 Coagulation
             2.6 Definitions of equipment performance
                 2.6.1 Efficiencies
                 2.6.2 Grade efficiency curves
         3 EQUIPMENT SELECTION PROCEDURE
             3.1 Introduction and scope
             3.2 Classification of gas cleaning equipment
             3.3 The analytical cut diameter
             3.4 Stepwise guide to the selection procedure
                 3.4.1 Step 1: Problem assessment
                 3.4.2 Step 2: Preliminary technical screening
                 3.4.3 Step 3: Emergence of suitable types
                 3.4.4 Step 4: Process screening
                 3.4.5 Step 5: Consideration of suitable types
                 3.4.6 Step 6: Preferencing of suitable types
                 3.4.7 Step 7: Accuracy of the problem statement
                 3.4.8 Step 8: Redetermination of the problem statement
                 3.4.9 Step 9: Detailed technical screening
                 3.4.10 Step 10: Emergence of suitable devices
                 3.4.11 Step 11: Modification of the problem statement
                 3.4.12 Step 12: Equipment tendering and tender evaluation
             3.5. The gas cleaning problem
                 3.5.1 Does a problem exist?
                 3.5.2 Can the problem be avoided?
                 3.5.3 The role of previous experience
                 3.5.4 The properties of the gas
                 3.5.5 The properties of the particles
                 3.5.6 Modification of the problem statement
             3.6 Conclusions
         4 NOMENCLATURE
         5 REFERENCES TO PART 1
         6 APPENDIX A THE ANALYTICAL CUT DIAMETER
         7 APPENDIX B BUYING CHECKLISTS
             7.1 Appendix B.1 Cyclone dust collectors
             7.2 Appendix B.2 Wet dedusters
             7.3 Appendix B.3 Fabric dust collectors
             7.4 Appendix B.4 Electrostatic precipitators
     Part 2: Cyclones
         1 OVERVIEW
         2 TYPES OF CYCLONE
         3 CYCLONE PERFORMANCE
             3.1 Effect of cyclone geometry
                 3.1.1 Reverse flow cyclones
                 3.1.2 Uniflow cyclones
                 3.1.3 Multicyclones
             3.2 Effect of operating conditions
             3.3 Scaling cyclone performance
                 3.3.1 Efficiency
                 3.3.2 Pressure drop
         4 CYCLONE INSTALLATIONS
             4.1 Fabrication
                 4.1.1 Manufacturing tolerances
                 4.1.2 Mechanical design
                 4.1.3 Abrasion protection
                 4.1.4 High temperature design
                 4.1.5 Refractory linings
                 4.1.6 Explosion venting
             4.2 Cyclone installations
                 4.2.1 Cyclones in series
                 4.2.2 Cyclones in parallel
                 4.2.3 Effect of inlet ducting
                 4.2.4 Cyclones for limited headroom
             4.3 Ancillary equipment
                 4.3.1 Gas outlet devices
                 4.3.2 Dampers
                 4.3.3 Hoppers
                 4.3.4 Dust removal valves
                 4.3.5 Vortex stabilisers
             4.4 Problems
                 4.4.1 Low efficiency
                 4.4.2 High pressure drop
                 4.4.3 Erosion
                 4.4.4 Solids build up
                 4.4.5 Handling friable materials
                 4.4.6 Vibration
         5 SPECIALISED EQUIPMENT
             5.1 Novel devices
             5.2 Demisting cyclones
             5.3 Sampling cyclones
         6 STATE OF THE SCIENCE
             6.1 Introduction
             6.2 Flow modelling in cyclones
                 6.2.1 Experimental studies
                 6.2.2 Inlet configuration
                 6.2.3 The Meissner-Muschelknautz flow models
                 6.2.4 Secondary flow effects
                 6.2.5 Other cyclone types
             6.3 Geometry independent modelling of cyclone grade efficiency curves
                 6.3.1 The equilibrium orbit model and the definition of S
                 6.3.2 The Leith and Licht model
                 6.3.3 The Dietz model
                 6.3.4 The Mothes and Loffler model
                 6.3.5 Prediction of experimental grade efficiency curves
                 6.3.6 Uniflow cyclones
             6.4 Pressure drop prediction
             6.5 Effect of solids loading
             6.6 Cyclone design methods
         7 NOMENCLATURE TO PART 2
         8 REFERENCES TO PART 2
     Part 3: Wet Dedusters
         1 OVERVIEW
         2 CLASSIFICATION OF WET DEDUSTER TYPES
             2.1 Irrigated Baffle Deduster
             2.2 Irrigated Fibrous Demisters
             2.3 Irrigated Cyclones
             2.4 Packed Bed Scrubbers
             2.5 Mobile Bed Scrubbers
             2.6 Preformed Spray Dedusters
             2.7 Plate Column Scrubbers
             2.8 Mechanically Assisted Wet Dedusters
             2.9 Self Induced Spray Dedusters
             2.10 Venturi Scrubbers
             2.11 Condensation Scrubbers
             2.12 Electrostatically Augmented Scrubbers
             2.13 Foam Scrubbers
             2.14 Hybrid Scrubbers
         3 ANCILLARY EQUIPMENT
             3.1 Scrubbing Liquid Clarification
             3.2 Entrainment Separation
             3.3 Corrosion and Erosion of Scrubbers
             3.4 Spray Nozzles
             3.5 Pumps
             3.6 Fans
         4 STATE OF THE SCIENCE
             4.1 Introduction
             4.2 Theoretical Modelling Concepts for Wet Dedusters
                 4.2.1 Inertial collection
                 4.2.2 Collection by interception
                 4.2.3 Diffusional collection
                 4.2.4 Phoretic effects
                 4.2.5 Theory of droplet formation
             4.3 Models for Collection Efficiency of Deduster Types
                 4.3.1 Irrigated baffle dedusters
                 4.3.2 Irrigated cyclones
                 4.3.3 Irrigated fibrous dedusters
                 4.3.4 Packed beds
                 4.3.5 Mobile bed scrubbers
                 4.3.6 Pre-formed spray dedusters
                 4.3.7 Plate column scrubbers
                 4.3.8 Mechanically assisted wet dedusters
                 4.3.9 Self induced spray dedusters
                 4.3.10 Venturi scrubbers
             4.4 Models Predicting Pressure Drop in Scrubber Types
                 4.4.1 Irrigated baffle dedusters
                 4.4.2 Irrigated cyclones
                 4.4.3 Irrigated fibrous dedusters
                 4.4.4 Packed bed scrubbers
                 4.4.5 Mobile bed scrubbers
                 4.4.6 Pre-formed spray dedusters
                 4.4.7 Plate column scrubbers
                 4.4.8 Mechanically assisted wet dedusters
                 4.4.9 Self induced spray dedusters
                 4.4.10 Venturi scrubbers
             4.5 Conclusions Regarding the State of the Science
         5 INDUSTRIAL DESIGN OF WET DEDUSTERS
             5.1 Introduction
             5.2 Selection of Wet Dedusters
                 5.2.1 Advantages and disadvantages of scrubber types
                 5.2.2 Scrubber User's Guide
                 5.2.3 Tender evaluation
             5.3 Sizing of Wet Dedusters
                 5.3.1 Grade efficiency calculations
                 5.3.2 The cut size concept
                 5.3.3 The contacting power concept
         6 DESIGN OF VENTURI SCRUBBERS
             6.1 Introduction
             6.2 Conceptual Design
                 6.2.1 General
                 6.2.2 Scoping design
                 6.2.3 Design by scaling
             6.3 Process Design
                 6.3.1 General
                 6.3.2 Pre- and post quencher design
                 6.3.3 Physical and thermodynamic properties
             6.4 Mechanical Design
                 6.4.1 Selection of Venturi geometry
                 6.4.2 Sizing of Venturis for a given pressure drop
                 6.4.3 Entrainment separation
                 6.4.4 Materials of construction
         7 NOMENCLATURE TO PART 3
         8 REFERENCES TO PART 3
     Part 4: Electrostatic Precipitators
         1. INTRODUCTION
         2. OVERVIEW
         3. TUBE VERSUS PLATE PRECIPITATORS
         4. GAS DISTRIBUTION IN THE ELECTRICAL SYSTEM
         5. DISLODGEMENT OF DUST FROM THE RECEIVING ELECTRODES
         6. RAPPING REQUIREMENTS
             6.1 Frequency of rapping
             6.2 Rapping intensity
             6.3 Conclusions on rapping requirements
         7. ASPECT RATIO
         8. DESIGN GAS VELOCITY
         9. SPECIFIC COLLECTION AREA
             9.1 Contact time
         10. ELECTRICAL FEATURES
             10.1 Effect of varying discharge electrode voltage
             10.2 Series electric field
         11. EFFECT OF GAS AND DUST PROPERTIES
             11.1 Electrical resistivity of dust and fume
             11.2 Dust agglomerate strength
             11.3 Conclusions - dust particle sizing and resistivity
             11.4 Properties of gases
             11.5 Discharge electrode voltage
         12. HIGH VOLTAGE RECTIFIER DESIGNS AND ASSOCIATED CONTROL CIRCUITS
             12.1 Power supply polarity
             12.2 Solid state rectifiers (high voltage)
             12.3 Variable AC supply to HT step-up transformers
             12.4 Automatic voltage control
             12.5 Pulse energisation
             12.6 Pulse interruption (pulse modulation, Variopuls - name varies with suppliers)
             12.7 Micro-processor base total energy management systems (TEMS)
             12.8 Air conditioning power systems
         13. INDUSTRIAL PRECIPITATOR CONSTRUCTION (MECHANICAL)
             13.1 Background
             13.2 Commercial designs of electrode systems - dry dust collection
                 13.2.1 Collecting electrodes
                 13.2.2 Discharge electrode (corona electrode)
                 13.2.3 Electrical Clearances
             13.3 Complete precipitator designs
             13.4 Wet precipitators
         14. STATE OF THE SCIENCE
             14.1 Motions of a Charged Particle in an Electric Field
             14.2 Corona Discharge
             14.3 Particle Charging Mechanism
             14.4 Prediction of the Charging Field
             14.5 Equations for Predicting Precipitation Performance
                 14.5.1 Theoretical simulation of ESPs (EPRI Manual Volume 1, 1987)
         NOMENCLATURE
         REFERENCES
     Part 5: Depth and Rigid Filters
         1. Introduction
         2. Granular Filters
             2.1 Savannah River and Related Filters
             2.2 Fixed Bed with Fluidised Expansion Cleaning
             2.3 Panel Beds
             2.4 Vibratory Beds
             2.5 Raked or Agitated Beds
             2.6 Dry Plate Scrubber
             2.7 Other Types of Filter Bed
             2.8 State of the Technology
         3. Filtration in Mobile Granular Beds
             3.1 Fluidised Beds
             3.2 Spouted Beds
             3.3 Electrofluidised Beds
         4. Fibrous Filters
             4.1 Ventilation filters
                 4.1.1 Fibre types
                 4.1.2 Construction
             4.2 High Efficiency Particulate Air (HEPA) filters
                 4.2.1 Rectangular filters
                 4.2.2 Circular filters
             4.3 Filter test methods
             4.4 The classification of filters by efficiency
         5. Magnetic Separation
         6. Ceramic Filters
             6.1 Ceramic Fibre Filters
                 6.1.1 Woven Fabric Filters
                 6.1.2 Felted Fabric Filters
             6.2 Rigid Porous Filters
                 6.2.1 Ceramic Cross-flow Filters
                 6.2.2 Ceramic Candle Filters
                 6.2.3 Ceramic Through-flow Filters
         7. Metallic Filters
             7.1 Woven Wire
             7.2 Knitted Wire
             7.3 Perforated Metals
             7.4 Expanded Metal
             7.5 Electroformed
             7.6 Porous Sintering
                 7.6.1 Metal powders
                 7.6.2 Metal fibres
             7.7 Growth of Metal Whiskers
         8. References
     Part 6: Fabric Filters
         1 OVERVIEW
         2 FABRIC FILTRATION MECHANISMS
             2.1 Initial Filtration
             2.2 Cake Development
             2.3 Cake Growth
             2.4 Cake Adhesion and Cohesion
             2.5 The Cleaning Phase
             2.6 Continued Filtration Operation
         3 FABRIC FILTER HARDWARE
             3.1 Typical Filter Layouts
             3.2 Filter Elements
             3.3 Filtration Velocity
             3.4 Positive or Negative Pressure Operation
             3.5 Continuous or Intermittent Operation
             3.6 Central or Unit Collectors
             3.7 Flow Regimes
         4 CLEANING TECHNIQUES
             4.1 Shake Cleaned Filters
                 4.1.1 Shake Cleaning of envelope bags
                 4.1.2 Cleaning times
                 4.1.3 Control
                 4.1.4 Shaking combined with reverse flow
                 4.1.5 Superficial filtration velocity
                 4.1.6 Shake cleaning of tubular bags
             4.2 Reverse flow cleaned filters
                 4.2.1 Low pressure reverse flow cleaning
                 4.2.2 flow cleaning
             4.3 Pulse Jet Filters
                 4.3.1 Pulse cleaning mechanisms
                 4.3.2 Injectors
                 4.3.3 Timer controllers
                 4.3.4 Pressure activated controllers
                 4.3.5 Pneumatically operated controllers
                 4.3.6 Features of pulse jet collectors
                 4.3.7 Plenum pulse filters
         5 FABRIC FILTER MEDIA
             5.1 Fibre types used for fabric filter media
             5.2 Textile technology concepts
                 5.2.1 Woven Fabrics
                 5.2.2 Needlefelt fabrics
                 5.2.3 Fabric qualities
                 5.2.4 Woven and Non-Woven Filter Fabrics
             5.3 Fibre degradation
                 5.3.1 The effects of temperature
                 5.3.2 Effects of chemical reagents
                 5.3.3 Effects of dust abrasiveness
             5.4 Specification of Filter Media
             5.5 Fabrics Available
             5.6 Fabric Finishes
             5.7 Thermal dimensional stability
             5.8 Fabric Filter Media for Gas Temperatures Above 250dC
         6 FILTER BAGS
             6.1 Tubular Element Diameter
             6.2 Tubular Element Lengths
             6.3 Envelope Elements
         7 ANCILLARY EQUIPMENT FOR PULSE JET FILTERS
             7.1 Requirements for Ancillary Equipment
             7.2 Compressed Air Supplies for Filters
                 7.2.1 Moisture in pulse jets
             7.3 The Compressed Air Reservoir and General Pipe work
             7.4 Diaphragm Valves And Pulse Tubes
             7.5 Venturi Injectors
             7.6 Support Cages
         8 OTHER ANCILLARY EQUIPMENT
             8.1 Dampers for Compartment Isolation
             8.2 Fans
             8.3 Flow Control Dampers
             8.4 Noise Control
             8.5 Dust Discharge and Handling Facilities
             8.6 Insulation and Preheating for Protection Against Condensation
         9 FABRIC FILTERS - STATE OF THE SCIENCE
             9.1 Fundamental Equations For Flow Through Filter Cakes
                 9.1.1 Deviations from theoretical behaviour
             9.2 Filter Cleaning
                 9.2.1 Cake bonding forces
                 9.2.2 Shake cleaning
                 9.2.3 Reverse air cleaning
                 9.2.4 Reverse pulse cleaning
             9.3 The Collection Efficiency Of Fabric Filters
             9.4 Modelling Procedures For Fabric Filters
         10 NOMENCLATURE
         11 REFERENCES
     Part 7: Demisting
         1 OVERVIEW
         2 DROPLET SIZE AND FORMATION
             2.1 Sources and mechanisms of liquid entrainment
             2.2 Changes in droplet size after formation
             2.3 Effect of contaminants
             2.4.Conclusions on the role of droplet size in the selection and design of demisters
         3 GRAVITATIONAL COLLECTORS
         4 INERTIAL COLLECTORS
             4.1 Knitted meshes
             4.2 Fine fibre demisters
             4.3 Wave plates
             4.4 Packed beds
         5 CYCLONIC COLLECTORS
             5.1 Applications
         6 DIFFUSIONAL COLLECTORS
         7 COULOMBIC FORCES
         8 GAS FLOW MALDISTRIBUTION AND MULTISTAGE DEMISTING
             8.1 Inertial devices in gravity separators
             8.2.Inertial devices and cyclonic separators
             8.3 Use of make-up water and washing sprays
         9 LIQUID SEALS
         10 STATE OF THE SCIENCE
             10.1 Gravitational collection
             10.2 Inertial impaction
             10.3 Centrifugal collection
             10.4 Generalised correlation for the efficiency of inertial collectors
             10.5 Diffusional collection
             10.6 Coulombic attraction
             10.7 Computational fluid dynamics studies
         11 EQUIPMENT DESIGN
         12 NOMENCLATURE TO PART 7
         13 REFERENCES TO PART 7

Part 1 Introduction to Gas Cleaning Technology
Part 2 Cyclones
Part 3 Wet Dedusters
Part 4 Electrostatic Precipitators
Part 5 Depth and Rigid Filters
Part 6 Fabric Filters
Part 7 Mist Removal
Part 8 Ancillary Equipment
Part 9 SPS Research
Part 10 Applied Technology
Part 11 Gas Purification

Volume GC I Part 1 Introduction to Gas Cleaning Technology

This part is split into three sections: an introduction to SPS Gas Cleaning Manual, gas cleaning fundamentals, and the selection of gas cleaning equipment. Gas cleaning fundamentals introduces the topics of particle size and size distributions as well as describing the science underlying the particle collection mechanisms used in the varied types of gas cleaning device available. The selection of gas cleaning equipment is considered from objective criteria and built into a stp-by-step selection procedure which ensures that all possibilities are considered and that equipment types are accepted / rejected for objective reasons. An expert system encapsulating the selection procedure is planned.


Volume GC I  Part 2 Cyclones.

This part describes the science and technology of gas cyclones. It covers topics of cyclone type, performance, sizing procedure, practical considerations and scientific principles of cyclone performance.


Volume GC I  Part 3 Wet dedusters.

This part describes the practical and scientific principles of a wide range of wet dedusters. Topics covered include classification of scrubber type, ancillary equipment, modelling concepts and industrial design.


Volume GC I  Part 4 Electrostatic Precipitators.

This part describes the science and technology of electrostatic precipitators. It covers electrostatic precipitator hardware, including design features, construction principles and control systems. Basic charging and field theory is covered, as well as the Deutsch equation and it use. Finally a comprehensive section on Design, Specification and Selection includes advice on troubleshooting.


Volume GC I  Part 5 Depth and Rigid Filters.

Volume GC I  Part 6 Fabric filters.

This part describes the science and technology of fabric filters. It covers fabric filtration mechanisms, hardware, cleaning techniques, filter media, filter bags, ancillary equipment for pulse jet filters, other ancillary equipment and the science of fabric filtration


Volume GC I  Part 7 Demisting.

This part describes the practical and scientific principles of a wide range of demisting devices. Topics covered include droplet formation, demister types (grouped under collection mechanisms), performance, sizing technique and underlying scientific principles.


Volume GC I  Parts 5, 8, 9, 10 and 11.
(Existing Report SAR15)

The report provides comprehensive coverage of gas cleaning in an easy to use way. It has been widely used as a company reference and training manual in the subject. The report highlights the large gap which exists between the industrial practice of gas cleaning and the understanding of the physics of the process. This analysis enabled the report to form the basis of the SPS gas cleaning research programme. The report covers the empirical aspects of the subject in state of the art sections which are kept distinct from the more theoretical analysis in the state of the science sections. The report begins with a simple to read introduction to the important theoretical concepts which underlie the subject. Remaining chapters are devoted respectively to cyclones, wet dedusters, electrostatic precipitators and filters. It concludes with some simple suggestions for selecting gas cleaning equipment.