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GC 10: Applied Technology

GC 10: Applied Technology
     Part 1: Gas Cleaning - Particle Size
     Part 2: Gas Cleaning - Fire and Explosion Hazards
         1 INTRODUCTION
         2 FIRE AND EXPLOSION HAZARDS ASSOCIATED WITH DUST
             2.1 The Nature of the Hazard
                 2.1.1 Combustion in dust clouds
                 2.1.2 Burning of dust layers and deposits
                 2.1.3 Burning of bulk dust
             2.2 Sources of Ignition
             2.3 Characterisation of Potential Hazards
                 2.3.1 Explosibility classification tests
                 2.3.2 Minimum ignition temperature
                 2.3.3 Maximum permissible oxygen concentration
                 2.3.4 Minimum explosible concentration
                 2.3.5 Minimum ignition energy
                 2.3.6 Maximum explosion pressure and maximum rate of pressure rise
                 2.3.7 Index of explosibility
         3 FIRE AND EXPLOSION HAZARDS ASSOCIATED WITH GASES AND VAPOURS
         4 FIRE AND EXPLOSION PRECAUTIONS - GENERAL PRINCIPLES
             4.1 Prevention Measures
                 4.1.1 Prevention of dust clouds and deposits
                 4.1.2 Elimination of ignition sources
                 4.1.3 Inerting
             4.2 Protection
                 4.2.1 Containment
                 4.2.2 Venting
                 4.2.3 Explosion suppression
                 4.2.4 Limiting the spread of an explosion
         5 FIRE AND EXPLOSION HAZARDS AND PRECAUTIONS IN GAS CLEANING APPLICATIONS
             5.1 Cyclones
             5.2 Filters
             5.3 Electrostatic Precipitators
             5.4 Scrubbers
             5.5 Ducts
         6 CONCLUSION
         7 REFERENCES
         8 NOMENCLATURE
     Part 3: Gas Cleaning - Hostile and Difficult Conditions
         1 INTRODUCTION
         2 GAS CLEANING UNDER CONDITIONS OF HIGH TEMPERATURE
             2.1 Introduction
             2.2 The effect of temperature and pressure on gas cleaning mechanisms
                 2.2.1 Fluid drag
                 2.2.2 Gravitational and centrifugal separation
                 2.2.3 Inertial impaction
                 2.2.4 Interception
                 2.2.5 Diffusion
                 2.2.6 Electrostatic attraction
                 2.2.7 Flux forces
                 2.2.8 Particle agglomeration
                 2.2.9 Summary of the effects of temperature and pressure on particle collection mechanisms
             2.3 Gas cleaning applications up to approximately 300?#176;C
                 2.3.1 Cyclones
                 2.3.2 Wet Scrubbers
                 2.3.3 Filters (fibre, fabric and granular)
                 2.3.4 Electrostatic precipitators
             2.4 Cleaning hot gas at temperatures above 300?#176;C
                 2.4.1 Cyclones
                 2.4.2 Scrubbers
                 2.4.3 Filters
                 2.4.4 Electrostatic precipitators
         3 GAS CLEANING UNDER CONDITIONS OF HIGH HUMIDITY
             3.1 General humidity considerations
             3.2 The effect of humidity on cyclones
             3.3 The effect of humidity on filtration
             3.4 The effect of humidity on electrostatic precipitators
         4 GAS CLEANING UNDER HIGH PRESSURE CONDITIONS
             4.1 Introduction
             4.2 Cyclones
             4.3 Scrubbers
             4.4 Filters
             4.5 Electrostatic precipitators
         5 GAS CLEANING INVOLVING REACTIVE OR AGGRESSIVE DUSTS, AEROSOLS AND GASES
             5.1 Introduction
             5.2 Acid dewpoints
             5.3 Erosion
             5.4 Corrosion and wear in cyclones
             5.5 Corrosion and wear in scrubbers
             5.6 Corrosion and wear in filters
             5.7 Corrosion and wear in electrostatic precipitators
         6 GAS CLEANING INVOLVING COHESIVE, ADHESIVE AND FIBROUS DUSTS
             6.1 Introduction
             6.2 Cohesive dusts
             6.3 The adhesion of dusts to surfaces
         7 CONCLUSIONS
         8 REFERENCES
         9 NOMENCLATURE
     Part 4: Gas Cleaning - Stringent Conditions
         1 INTRODUCTION
         2 STRINGENT GAS CLEANING SITUATIONS
             2.1 Toxic Dusts
             2.2 Radioactive Particulates
             2.3 Air Sterilisation
             2.4 Ventilation and Air Conditioning
             2.5 Clean Rooms
         3 GAS CLEANING UNDER STRINGENT CONDITIONS
             3.1 Cyclones and Scrubbers
             3.2 Fabric Filters
             3.3 Electrostatic Precipitators
             3.4 Fibre Filters
                 3.4.1 Clean air filters
                 3.4.2 High efficiency filters
             3.5 Filter Test Methods
                 3.5.1 Test Equipment
                 3.5.2 Aerosols and test dusts: generation, characteristics and measurement of filter performance
                 3.5.3 Discussion of test methods
         4. CONCLUSIONS
         5 REFERENCES
         6 NOMENCLATURE
     Part 5: Gas Cleaning - High Temperature and Pressure
         1. INTRODUCTION
             1.1 The Need for Hot Gas Cleaning
                 1.1.1 Advanced Power Generation
                 1.1.2 Other Processes
             1.2 Gas Cleaning Processes
             1.3 Effects of Temperature and Pressure.
                 1.3.1 Gas Properties
                 1.3.2 Gas-Particle Interaction
                 1.3.3 Particle-Particle Interaction
         2. INERTIAL SEPARATORS
             2.1 Introduction
             2.2 Theoretical Analyses
                 2.2.1 Scaling Approach
                 2.2.2 Mechanistic Analyses
             2.3 Experimental Performance Evaluations
                 2.3.1 Early Work at High Temperature
                 2.3.2 Recent Evaluations
                 2.3.3 Cyclone Performance Predictions for Gas Turbine Application
             2.4 Novel Cyclone Designs
                 2.4.1 Air-Shielded Cyclones
                 2.4.2 Electrocyclone
                 2.4.3 Cardiff Cyclone
                 2.4.4 Cyclocentrifuge
                 2.4.5 Wedge Separator
                 2.4.6 Rotary Flow Cyclone
             2.5 Conclusions
         3. ELECTROSTATIC PRECIPITATORS
             3.1 Effects of Temperature and Pressure
                 3.1.1 Corona Discharge
                 3.1.2 Particle Charging
                 3.1.3 Particle Migration
                 3.1.4 Particle Collection and Discharge
             3.2 Performance Evaluation
             3.3 Conclusions
         4. FILTERS
             4.1 Introduction
             4.2 Barrier Filters
                 4.2.1 Filter Medium Requirements
                 4.2.2 Metal Filters
                 4.2.3 Ceramic Filters
                 4.2.4 Conclusions on Barrier Filters
             4.3 Granular Bed Filters
                 4.3.1 Fundamental Aspects
                 4.3.2 Fixed or Moving Bed Filters
                 4.3.3 Fluidised Bed Filters
                 4.3.4 Conclusions on Granular Bed Filters
         5. WET SCRUBBERS
             5.1 Introduction
             5.2 Experimental Performance Evaluations
         6. GENERAL CONCLUSIONS
         7. APPENDIX A DIMENSIONAL ANALYSIS OF CYCLONE PERFORMANCE
         8. NOMENCLATURE
         9. REFERENCES
     Part 6: Gas Cleaning - Sampling and Measurement
         1. INTRODUCTION
         2. SAMPLING AND MONITORING PARTICULATES
             2.1 Introduction
             2.2 Sampling of Particulates in Ducts
                 2.2.1 Pitot Tubes
                 2.2.2 Duct Sampling Equipment for Compliance with Standards
                 2.2.3 Alternative Designs of Sampling Equipment
                 2.2.4 Accuracy of Dust Concentration Measurements
                 2.2.5 Errors Due to Anisokinetic Sampling
                 2.2.6 Particle Transport Through Sampling Tubes
                 2.2.7 Nozzles and Nozzle Design
             2.3 Sampling of Airborne Particles
                 2.3.1 Methods for Ambient Particulate Measurements
                 2.3.2 Methods for Workplace Particulate Measurements
                 2.3.3 Depositional Methods of Particulate Measurement
             2.4 Sampling of Airborne Particles for Health Monitoring
                 2.4.1 Sampling Principles
                 2.4.2 Application of Standards
                 2.4.3 Deposition in the Respiratory Tract
                 2.4.4 Respirable Dust Measurement
             2.5 Filter Media Employed in Particulate Sampling
         3 COLLECTION TECHNIQUES FOR PARTICULATE MEASUREMENT
             3.1 Cascade Impactors
                 3.1.1 Practical Use of Cascade impactors
             3.2 Impingers
             3.3 Virtual Impactors
             3.4 Cyclones
             3.5 Thermal Precipitation
             3.6 Electrostatic Sampling
         4. ON-LINE TECHNIQUES FOR PARTICULATE MEASUREMENT
             4.1 Optical Measurement of Concentration
                 4.1.1 Transmissometers
                 4.1.2 Impacimeter
                 4.1.3 Light Scattering Monitors
                 4.1.4 Integrating Nephelometer
             4.2 Optical Measurement of Particle Size
                 4.2.1 Light Scattering Techniques
                 4.2.2 Light Diffraction Techniques
             4.3 Beta Attenuation Instruments
             4.4 Electrical Aerosol Analysers
             4.5 The Diffusion Battery and Condensation Nuclei Counter
                 4.5.1 Diffusion Batteries
                 4.5.2 Condensation Nuclei Counters
             4.6 Piezoelectric Aerosol Monitors
             4.7 Contact Electricity Aerosol Monitors
             4.8 The Performance of Instruments for On-line Particle Measurement
                 4.8.1 On-line Instruments for Particle Source Emissions
                 4.8.2 On-line, Direct Reading Instruments used in the Working Environment
                 4.8.3 On-line Instruments Used for the measurement of Atmospheric Particles
         5. EQUIPMENT SELECTION
             5.1 Sampling Probes - Duct extractive
             5.2 Sampling Probes - Cascade impactors
             5.3 Impingers
             5.4 High and Low Volume Ambient Samplers
             5.5 Workplace Samplers
             5.6 Deposit Gauges
             5.7 Thermal Precipitators
             5.8 Electrostatic Samplers
             5.9 Diffusion Battery and Condensation Nuclei Counter
             5.10 Transmissometers
             5.11 Light Scattering Continuous Analysers
             5.12 Beta Attenuation Instruments
             5.13 Piezo-electric Aerosol Monitor
             5.14 Contact Electricity Aerosol Monitor
             5.15 CERL Mk II Flue Dust Monitor (Impacimeter)
             5.16 Directory of Manufacturers and UK Agents
         6. CONCLUDING REMARKS
         7. REFERENCES
     Part 7: Optical Dust Density Meters for Monitoring of Particulates Flue Gases
         1. INTRODUCTION.
         2. LEGISLATION AND STANDARDS APPLYING TO PARTICULATE EMISSIONS AND THEIR MEASUEMENT
             2.1 UK Legislation and Regulations
             2.2 Standards Applying to Sampling and Measurement.
                 2.2.1 Manual Extractive Sampling
                 2.2.2 Automated Measurement using Optical Opacity
                 2.2.3 Low Level Particulates Monitoring
         3. DUST DENSITY METERS - DESCRIPTION AND FUNCTION.
             3.1 Erwin Sick RM41.
             3.2 ERT Omega.
         4. PHYSICAL AND OPERATIONAL PRINCIPLES UNDERLYING MEASUREMENT AND METER FUNCTION.
             4.1 Optical Principles.
             4.2 Operational Factors Influencing Meter Function.
                 4.2.1 Location
                 4.2.2 Alignment
                 4.2.3 Fouling
                 4.2.4 Type of Plant
                 4.2.5 Variations in Flow
         5. ANALYSIS OF DATA FROM INCINERATOR AUDITS.
         6. CONCLUSIONS.
         7. RECOMMENDATIONS FOR FURTHER DEVELOPMENT.
         8. REFERENCES.
     Part 9: Gas Cleaning Equipment Troubleshooting
         1. Introduction
         2. Cyclones
             2.1 Reverse Flow Cyclone Efficiency for Dust Collection
                 2.1.1 Overview of Possible Problems
                 2.1.2 Step-wise Assessment

This volume will deal with specialist applications of gas cleaning technology.

Part 2  Gas cleaning involving fire and explosion hazard
Part 3  Gas cleaning under hostile and difficult conditions
Part 4  Gas cleaning under stringent conditions
Part 5  Removal of particles from gases at high temperature and pressures
Part 6  The sampling and measurement of particles suspended in gases
Part 7  The application of optical dust density meters to the monitoring of particulate burdens in flue gases
Part 8  Technological Gatekeeping
Part 9  Troubleshooting

Volume GC X  Part 2 Gas cleaning involving fire and explosion hazards.

A large number of dust fires and explosions occur in gas cleaning equipment. In many instances extensive damage and even fatalities are caused. In the light of these facts, this report considers the nature of such hazards, the characterisation of dusts and vapours and the precautions that need to be taken to minimise hazards in gas cleaning applications. The nature of the combustion of dust clouds and the burning of dust layers or deposits are outlined briefly. Sources of ignition are discussed and the tests needed to characterise the potential hazards are described. Fire and explosion precautions are summarised and include prevention and protection. Preventative measures described include suppression of dust clouds and the avoidance of accumulations, the prevention of ignition and inerting with gases or powders. Protective measures include containment, relief venting and suppression using extinguishing agents. The design of containment and relief systems is also discussed. Cyclones, filters, electrostatic precipitators, scrubbers and associated ductwork are examined to identify potential sources of ignition and the sources of high dust concentration. The applicability of precautionary methods to the various types of gas cleaning equipment is discussed in some detail.


Volume GC X  Part 3 Gas cleaning under hostile and difficult conditions.

With increasing requirements to control emissions to the atmosphere and with the development of more advanced technologies, the areas of application of gas cleaning are constantly being extended into more demanding environments. This report reviews gas cleaning technology under a range of hostile and difficult conditions. First, the effects of temperature and pressure on the basic collection mechanisms are discussed. The types of process requiring gas cleaning at high temperatures and pressures are reviewed and the range of application and the limitations of cyclones, scrubbers, filters and electrostatic precipitators are reviewed. The factors affecting erosion and corrosion in the various components of gas cleaning equipment are then summarised and precautionary measures commonly adopted described. Particular attention is given to humidity and the calculation of acid dewpoints associated with combustion products. A section is then devoted to the way that the performance of gas cleaning equipment can be significantly affected by the physical nature of the bulk collected dust, both in the way that it adheres to the machinery surfaces and in its ability to form a strong compacted deposit. This is a topic which has not received much attention elsewhere in the literature.


Volume GC X  Part 4 Gas cleaning under stringent conditions.

In some gas cleaning applications the particle concentrations that are acceptable in the cleaned gas are very low. This may be because the contaminant is extremely toxic either to personnel or to biochemical processes, or because the presence of particles in mechanical components of delicate instruments is deleterious. Such high levels of gas cleanliness are achieved, almost exclusively, by using fibrous filters although the present report does consider the limitations of other devices. The levels of contamination, the required cleaning efficiencies and the general management of air flows is considered for a number of applications. These include: toxic dusts, radioactive particulates, air sterilisation (for biochemical processes), ventilation, air conditioning and clean rooms. Cyclones, scrubbers, bag filters and electrostatic precipitators are all considered but the major interest is in fibrous filters. These are considered in two classes. The first class is used for ventilation and air conditioning applications and the various designs, performance characteristics and methods of operation are described. The second class or HEPA (High Efficiency Particulate Air) filters can achieve collection efficiencies in excess of 99.99% for all particles. Their construction, installation, operation, performance and disposal are discussed in detail. Both classes of fibrous filter are required to conform to strict requirements which necessitates rigorous testing. A number of test procedures have been developed using different test rigs, different aerosols and different methods of measuring penetration. The various test procedures are examined in some detail and their relative merits discussed.


Volume GC X  Part 5 The removal of particles from gases at elevated temperatures.

Since the mid 1970ís a great deal of research has been conducted with a view to solving the problems associated with cleaning the combustion gases produced by advanced designs of coal fired power plants. Such gases, derived from fluidised bed combustors for example, may be at temperatures up to 1300 K and pressures up to 15 bar. Extra efficiency of coal to electricity conversion may be obtained by expanding these gases directly through a turbine. The economic success of such advanced power generation projects depends crucially on the degree to which the gases can be cleaned hot. A great deal has been learned about this very difficult problem and much of it is of use in the process industries where there are frequent occurrences of lower temperature applications which, whilst less demanding, are nonetheless beyond the range of conventional technology. The extensive research programmes which have been conducted in this area, mainly in the US, are critically reviewed. The lessons learned concerning the application of cyclones, electrostatic precipitators, wet dedusters and especially filters are summarised.


Volume GC X  Part 6 The sampling and measurement of particles suspended in gases.

This report deals with the determination of the concentration and size distribution of airborne dusts, primarily in relation to gas cleaning. Three distinct situations are identified: the sampling and monitoring of particulates in `ducts`, in the `ambient atmosphere` and for health monitoring in the `workplace environment`. Sampling techniques for particle concentration determination are described, with particular attention being given to the sampling from ducts. Consideration is given to topics such as statutory regulations, sampling locations, flow measurement, accuracy, assessment of health risks and standardised techniques. Particle size analysis techniques which involve the collection of a sample of the material are reviewed. Principal consideration is of cascade impactors and a practical guide is given for their use. Techniques are also described for the direct measurement of concentration and/or particle size. Principally these are optical techniques, although consideration is also given to other sensing methods. The report concludes with a summary of the most commonly encountered types of sampling or measurement device, their approximate specification and source of supply.


Volume GC X  Part 7 The application of optical dust density meters to the monitoring of particulate burdens in flue gases.

This part reviews the performance of different optical dust monitors for continuous monitoring of dust emissions from incinerators. Comparisons are given between dust emission rates determined by extractive sampling and those recorded by monitors. The theoretical operation of these devices is also reviewed and conclusions regarding their suitability are drawn.


Volume GC X  Part 8 Technological Gatekeeping.

SPS GC TG001 The Aerodynamic Module (ADM). This is the first of a new style SPS document which aims to review novel developments in the technology, in this case in gas cleaning. The ADM is a development of the traditional Vane or Louvre dry inertial separator, claiming to achieve efficiency which is better than traditional devices, possibly comparable with a cyclone yet with lower pressure drop.


Volume GC X  Part 9 Troubleshooting.

Sections of this manual part will include :-

  1. Introduction
  2. Particulate Gas Problems
  3. Equipment Failure Modes
  4. Recommended Procedures