CEMENT INDUSTRY

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CEMENT INDUSTRY

• GRUPO 5
• PILAR DELICADO HERRERAS
• REBECA DIEZ MORALES
• CRISTINA MARTÍN SERRANO

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GENERAL INFORMATION ABOUT CEMENT INDUSTRY

• Cement is a basic material for building and civil
  engineering construction.
• Cement is a finely ground, non-metallic,
  inorganic powder when mixed with water forms a
  paste that sets and hardens.
• World cement production has grown steadily since
  the early 1950s, withincreased production in
  developing countries, particularly in Asia.

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CEMENT PRODUCTION IN THE UEAND THE WORLD

• Producers in the European Union have increased
  cement output per man/year from 1700 tonnes in
  1970 to 3500 in 1991.
• As a result of the introduction of larger scale
  production units.
• The number of people employed in the cement
  industry in the European Union is now less than
  60000.

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EMISSIONS

• The emissions from cement plants which cause
  greatest concern are
• Nitrogen oxides (NOx)
• Sulphur dioxide (SO2)
• Dust
• Carbon oxides (CO, CO2)
• Volatile organic compounds
• Polychlorinated dibenzodioxins (PCDDs) and
  dibenzofurans (PCDFs)
• Metals and their compounds

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APPLIED PROCESSES AND TECHNIQUES

• It begins with the decomposition of calcium
  carbonate (CaCO3) at about 900C to leave calcium
  oxide (CaO, lime) and liberate gaseous carbon
  dioxide (CO2).

CALCINATION
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MAIN PROCESS ROUTES FOR THE MANUFACTURE OF CEMENT

• There are four main process routes
• 1) Dry process raw materials are ground and
  dried to raw meal in the form of a flowable
  powder.
• 2) Semi-wet process the slurry is first
  dewatered in filter presses.

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MAIN PROCESS ROUTES FOR THE MANUFACTURE OF CEMENT

• 3) Semi-dry process dry raw meal is pelletised
  with water and fed into a grate preheater before
  the kiln or to a long kiln equipped with crosses.
• 4) Wet process, the raw materials (often with
  high moisture content) are ground in water to
  form a pumpable slurry.

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SUB-PROCESSES

• Winning of raw materials
• Raw materials storage and preparation
• Fuels storage and preparation
• Clinker burning
• Cement grinding and storage
• Packing and dispatch

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TECHNIQUES TO CONSIDER THE DETERMINATION OF BAT

• Consumption of raw materials
• Reduce the total consumption of raw materials.
• Use of energy
• To optimise the input of energy.
• Process selection
• The selected process will affect the releases of
  all pollutants, and will also have a significant
  effect on the energy use.
• General techniques
• Optimisation of the clinker burning process is
  usually done to reduce the heat consumption, to
  improve the clinker quality and to increase the
  lifetime of the equipment
• Reduction of emissions, such as NOx, SO2 and
  dust, are secondary effects of this optimisation.

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TECHNIQUES TO CONSIDER THE DETERMINATION OF BAT

• Careful selection and control of substances
  entering the kiln can reduce emissions.
• Specific techniques
• Control NOx emissions
• Control SO2 emissions
• Control dust emissions
• Control other emissions to air

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DUST EMISSIONS

• Main point sources
• Kiln systems
• Clinker coolers
• Cement mills
• Techniques for controlling it
• Electrostatic precipitators
• Fabric filters
• Fugitive dust abatement

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ELECTROSTATIC PRECIPITATORS

• Generate an electrostatic field.
• The particles become negatively charged and
  migrate towards positively charged collection
  plates.
• The collection plates are vibrated periodically,
  dislodging the material so that it falls.
• CONDITIONS
• High temperatures (up to approximately 400ºC).
• High humidity.

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ELECTROSTATIC PRECIPITATORS

• Efficiency is affected by
• Flue gas flow rate
• Strength of the electric field
• Particulate loading rate
• SO2 concentration
• Moisture content
• Shape and area of the electrodes

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ELECTROSTATIC PRECIPITATORS

• Electronics precipitators can reduce levels down
  to 5-15 mg/m3 as monthly average.
• Besides dust, the EP also removes substances that
  adsorb to the dust particles, such as dioxins and
  metals if present.
• EPs are not installed if emissions at startups
  and shut downs are very high.

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FABRIC FILTERS

• Fabric membrane which is permeable to gas but
  which will retain the dust.
• As the dust cake thickens, the gas pressure drop
  across the filter increases Periodic
  cleaning
• The use of modern fabric filters can reduce dust
  emissions to below 5 mg/m3.
• Also removes substances that adsorb to the dust
  particles, such as dioxins and metals.

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FUGITIVE DUST ABATEMENT

• Fugitive emission sources mainly arise from
  storage and handling of substances and from
  vehicle traffic at the manufacturing site.
• Some techniques for fugitive dust abatement are
• Open pile wind protection
• Water spray and chemical dust suppressors
• Paving, road wetting and housekeeping
• Mobile and stationary vacuum cleaning
• Ventilation and collection in fabric filters
• Closed storage with automatic handling system

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COMPARISON
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BEST AVAILABLE TECHNIQUES FOR THE CEMENT INDUSTRY

• The BAT for the production of cement clinker is
  considered to be a dry process kiln with
  multi-stage preheating and precalcination.
• Process control optimisation.
• The use of modern, gravimetric solid fuel feed
  systems.
• Preheating and precalcination to the extent
  possible, considering the existing kiln system
  configuration.
• The use of modern clinker coolers.

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BEST AVAILABLE TECHNIQUES FOR THE CEMENT INDUSTRY

• Heat recovery from waste gas.
• Power management systems.
• Grinding equipment and other electricity based
  equipment with high energy efficiency.
• Careful selection and control of substances
  entering the kiln can reduce emissions.

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BAT FOR REDUCING DUST EMISSIONS

• The combination of the above described general
  primary measures and
• Minimisation/prevention of dust emissions from
  fugitive sources.
• Efficient removal of particulate matter from
  point sources by application of
• - Electrostatic precipitators with fast measuring
  and control equipment to minimise thenumber of CO
  trips.
• - Fabric filters with multiple compartments and
  burst bag detectors.
• The BAT emission level associated with these
  techniques is 20-30 mg dust/m3 on a daily average
  basis.

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EMERGING TECHNIQUES IN THE CEMENT INDUSTRY

• Fluidised bed cement manufacturing technology
• Staged combustion combined with SNCR

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FLUIDISED BED CEMENT MANUFACTURING TECHNOLOGY

• Consists of a suspension preheater (SP), a
  spouted bed granulating kiln (SBK), a fluidised
  bed sintering kiln (FBK), a fluidised bed
  quenching cooler (FBK) and a packed bed cooler.
• SP conventional 4-stage cyclone preheater.
• Granulating kiln granulating the raw meal into
  granules of about 1,5-2,5 mm diameter at a 1300ºC.

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FLUIDISED BED CEMENT MANUFACTURING TECHNOLOGY

• The sintering of the granules is completed at a
  1400ºC.
• The fluidised bed quenching cooler quickly cools
  the cement clinker from 1400 to 1000ºC.
• The cement clinker is cooled down to about 100ºC
  in the packed bed cooler.

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• Configuration of the 20 tonnes clinker/day
  fluidised bed cement kiln system

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FLUIDISED BED CEMENT MANUFACTURING TECHNOLOGY

• The final target of the technical development of
  the fluidised bed cement kiln system are
• Reduction of heat use by 10-12.
• Reduction of CO2 emission by 10-12.
• A NOx emission level of 380 mg/m3 or less
  (converted to 10 O2).
• To maintain the current SOx emission level.
• Reduction of construction cost by 30.
• Reduction of installation area by 30.

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STAGED COMBUSTION COMBINED WITH SNCR

• In theory, a combination of staged combustion and
  SNCR could be comparable to SCR in performance,
  that is NOx emission levels of 100-200 mg/m3.
• This combination is considered very promising by
  suppliers but is not yet proven.

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CEMENT INDUSTRY

• GRUPO 5
• PILAR DELICADO HERRERAS
• REBECA DIEZ MORALES
• CRISTINA MARTÍN SERRANO