Managing Emissions to the Atmosphere Flashcards
Types of Emissions to the Atmosphere?
> Gaseous (substances which remain as a gas at process temperatures and pressures, eg CO, N, Ozone
> Vapour (gaseous state of materials which are liquid at normal temperatures and pressures)
> Mist (fine liquid droplets, usually nucleated by a particle)
> Fume (small solid particles produced by condensation of vapours or gaseous combustion. particle size 01 - 1 micron)
> Smoke (particle size 01 - 1 micron)
> Dust (any size or shape of particle, crystalline or amorphous)
> Grit (particles exceeding 75 microns)
> Fibre (solid particles with an increased aspect ratio (ratio of length to width))
Pollutant Impact - what are the main sources and what are the effects - Particulates
Main Sources - combustion of fuels and activities such as quarrying and truction
Effects - contribute to cardiovascular and respiratory (particles less than 10 microns particularly linked to adverse health conditions)
Pollutant Impact - Oxides of Carbon
Main Sources - combustion of fossil fuels, especially in electricity generation and road transport
Effects - CO2 main pollutant implicated in climate change. Also reduces the capacity of the blood to carry oxygen
Pollutant Impact - Oxides of Nitrogen
Main Sources - any combustion activity taking place in air. Road transport, and electricity generation are important sources
Effects - NO2 and NO (nitrogen dioxide and nitric oxide) are often referred as Noxious. Linked to inflammation of lung tissue, respiratory symptoms, reduce leaf growth, also reacts with VOC’s (volatile organic compounds) to create toxic-ozone and other components of photochemical smog.
Pollutant Impact - Oxides of Sulphur
Main Sources -combustion of fossil fuels containing sulphur - such as coal and heavy oil used in power stations
Effects - sulphur dioxide causes constriction of the airways of the lungs. major contributor to acid-rain deposition.
Pollutant Impact - Polycyclic Aromatic Hydrocarbons (PAHs)
Main Sources -road transport, domestic coal and wood fires
Effects - potential carcinogenic and linked to lung and skin cancers
What are the sources and Pollutant Impacts of VOC’s (volatile organic compounds)
Main Sources - evaporation of liquid fossil fuels from transport and solvents used in industry
Effects - NO2 and NO (nitrogen dioxide and nitric oxide) are often referred as Noxious. Linked to inflammation of lung tissue, respiratory symptoms, reduce leaf growth, also reacts with VOC’s (volatile organic compounds) to create toxic-ozone and other components of photochemical smog.
Pollutant Impact - Methane
explosive, flammable and potent GHG.
Pollutant Impact - Low Level Ozone
Main Source - transport industry and secondary pollutant formed from reaction of O2 and VOC and NO in the presence of light.
Effects - short terms can cause temporary irritation to lungs, eyes and respiratory tract. Long term may reduce lung function.
Pollutant Impact - Asbestos
Main Source -may be re;easded from construction/demolition sites
Effects - causes respiratory illnesses and lung-cancer
Pollutant Impacts - Halogens
Main Source - refrigeration process and Many industrial processes (flouring, chlorine and bromine) highly reactive elements
Effects - toxic and damaging growth to plants. Halogenated refrigerant gases are strongly linked to destruction of ozone layer and climate change.
Pollutant Impacts - Toxic Metals
Main Sources - (lead, arsenic, cadmium, mercury, nickel) emitted from coal combustion ands industrial processes.
Effects - wide range of biochemical effects including damage to the nervous system.
Pollutant Impact - Other Toxics
Main Sources - road fuels, industrial processes. Notably benzene ands 1.3-butadiene.
Effects - carcinogenic
Impacts of Pollutants on Air Quality and Health
short-term to human health - irritation and inflammation of the airways, eyes, mouth and triggering Samatha attacks
Longer term - cardiopulmonary performance but may also be increased incidents of cancers.
What are the Key Pollution Areas
> Climate Change
Photochemical Smog
Acid Deposition
Ozone Layer Depletion
National Emission Ceiling Limits
Geneva Convention on Long-Range Transboundary Air Pollution 1979 (and eight associated protocols)
Gothenburg Protocol to Abate Acidification, Eutrophication and Ground Level Ozone 1999
What are the Elements of Monitoring Atmospheric Emissions?
sample, monitor and measure emissions (eg to demonstrate compliance with environmental permits)
The Principles of Monitoring Strategy
> which substances too sample
when to sample, for how long, how many samples
which technique method and equipment to use
where to sample from
collecting and reporting of data
quality assurances and control
safety
What are the Sampling Principles?
in terms of stack emission:
> sampling point - the specific position on the stack
> sampling or access points - points on stack, duct, flue through which access to the emission can be gained
> Isokinetic Sampling - technique of drawing sampling air through a probe containing a collection filter at the same rate as the gas flow though the stack
> Monitoring Approach - whether sampling is periodic or continuous
> Monitoring Technique - the analytical principles behind the monitoring (infrared, absorption, chemiluminescence etc)
> Monitoring Method - published/documented procedure for using the monitoring approach and technique.
> Monitoring Equipment - the instruments and apparatus used
What are the Two Main Monitoring Approaches?
Periodic Measurement
Continuous Emissions Monitoring (CEM)
What is the Control Hierarchy?
> Eliminate
Minimise
Render Harmless
What are the Particulate Control Devices?
> Settling Chambers
cyclones
fabric filters
wet scrubbers
electrostatic precipitators
water walls
What are wet scrubbers?
used to remove particulates from waste gas streams
principle is that water droplets are generated within the device and particles are captured by the droplets
droplets are then removed from the air stream - which is now clean
droplets collected as contaminated water and transported out of the device for treatment or disposal.
What are the types of wet scrubber?
> venture scrubbers
mechanically aided scrubbers
pup-aided scrubbers
wetted filer scrubbers
What are Electrostatic Precipitators?
particulate and droplets;et controlled device which uses electrical forces to remove particles from a dust laden air stream.
an area of ionised air molecules is established (usual;l;y around a wire) bu=y maintaining a very high voltage
this region of ionised air molecules is called a corona.
Particles flow through the corona, collect ions then become charged.
A ‘collector’ plate is maintained at the opposite polarity so charged particles migrate towards the plate.
What are water walls?
two common methods are rain guns and perimeter systems.
used to suppress dust and prevent it escaping from a confined area - commonly used in construction and demolition.
What are the Gas and Vapour Devices?
> Packed Columns
Activated carbon absorption devices
Incinerators
Dry Scrubbers
Coolers and Chillers
Peat Filter Beds
Bio Scrubbers
GHG Management Hierarchy
What are the two types of Activated carbon absorption devices?
process of absorption involves the retention of a gas or vapour molecule on the surface of a particle or droplet
> physical - involving intermolecular Vander Vaals forces
chemical reaction - involving activated absorption
. activated carbon
. activated alumina
. silica gel
. molecular sieves
What are the three types of incinerator devices?
> flare stacks - usually in petrochemical industry and are seen as tall stacks with flames on the top
thermal incinerators - chamber containing a burner unit., usually fuelled by natural gas which raises the temperature of the waste gas to a point where it reacts with the oxygen in the air
catalytic incinerator - allows oxidation reaction to occur at ba much ;lower temperature, around 400 degree centigrade.
What is a dry scrubber?
moisture free pollution abatement technologies, such as bag filters, absorption, electrostaticprecipitators and cyclones.
Used for treating pollutant emissions from numerous sources such as waste incinerators, biomass combustion or kilns.
What are coolers and chillers?
a device to reduce temperature or increase pressure to condense VOC vapours.
> contact callers - involves spraying cold water into a gas stream and cooling by direct contact
> surface coolers - devices that present the vapour with a cold surface
What are Peat Filter Beds?
large steel or concrete containers containing natural peat. Peat treated with micro-organisms and supplied with water and nutrients to encourage growth.
What are Bio-Scrubbers?
a gas scrubber that removes pollutants from the gas stream by the use of wash water, this waste water is then transferred to a bio9logical reactor where pollutants are biologically degraded.
Green House Gas (GHG) Hierarchy details?
> eliminate
reuce - make operations more efficient for processes, fleet and energy management
substitute - reduce GHJG intensity of energy use
compensate - carbon offsetting
