Transcript Ceramics - IQ

CERAMICS
Group 8
Blanco González, José Manuel
Gómez Rojo, Vidal
Llorente Pérez, Cristina
Sanz Moral, Luis Miguel
General Process
Energy Consumption
PROCESS
ENERGY
Kiln firing
Drying of intermediates Intensive Energy (almost natural gas, LPG and fuel)
Shaped ware
Plant
Electrical Energy
Machinery
On-site transportation
Diesel fuel
Water Consumption
Water is used in all ceramic processes.
 It can be used:
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 As
a raw material
For the body and its preparation (low quality water)
 For glazes (good quality water)
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 As
a washing fluid (good quality water)
 As a cooling medium (good quality water)
Emissions to air
Significant emissions to air arise in the
firing process
 Emissions vary:
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 From
site to site depending on the different
clay raw materials (geological and
geographical variations)
 From country to country
Emissions to air
Raw Materials Consumption
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There are a number of mineral species called clay
minerals, but the most important are:
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Kaolinite
Montmorillonite
Halloysite
Advanced ceramic products:
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contain only a small fraction of clay or none at all
Based on the following materials:
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Oxides
Carbides
Nitrides
Borides
Other metal ions
Techniques to consider the
determination of BAT
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At this point, we consider the techniques that
have potential for achieving a high level of
environmental protection
Management systems, process-integrated and
end of pipe measures are included
Other procedures:
Re-use of materials and energy
 Prevention and control
 Minimisation and recycling
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Principal techniques to consider
The principal techniques to consider are in the following
fields:
 Reduction
of energy consumption
 Emissions of dusts
 Gaseous compounds
 Process waste water
 Process losses or waste
 Noise
Reduction of energy consumption
We can reduce energy by the following ways:
Improved design of kilns and dryers.
 Recovery of excess heat from kilns.
 Cogeneration/Combined heat and power plants
 Substitution of HFO and SF by LEF.
 Modification of ceramic bodies.
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Emissions of dusts
It include techniques and measures to
prevent diffuse and channeled emissions:
 Measures
 Separation/filter
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systems:
Centrifugal separators
Filters: bas or lamellar
Wet dust separators
Electrostatic precipitators
Gaseous compounds
- Is very important to reduce the input of pollutant
precursors:
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Oxides of sulphur
Oxides of nitrogen
Inorganic chlorine compounds
Inorganic fluorine compounds
VOC´S
- Addition of Calcium rich additives
- Process optimization, an example is: Reduction of vapour
water levels in the kiln gases
- Sorption plants (adsorbers and absorbers)
- Afterburning
Process waste water
Water has in our case a lot of uses:
raw material
 a scrubing agent
 a heat exchange vehicule
 a cleaning agent
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Objetive is to reduce the use of process water.
To reach these, process optimisation measures and
process waste water treatment systems are employed
Process losses or waste
We have two methods where we can improve
the process of manufacturing ceramics:
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Sludge arising in the manufacture of ceramic products.
This could be recycling systems or re-use in other products
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Solid process looses/ solid waste
This solid process looses can be re-use as raw material.
Considerations about noise
Applying measures at the source of the noise:
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Enclosure the unit
Build up noise protection walls
Double walls
Vibration insulation
Use silencers
Secondary noise protection measures:
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Thicker walls
Sound insulation of the windows
Obviously also gates and windows have to be closed
and cautiously driving reduces the noise emissions.
And last, there is a time-limiting of noise intensive work.
Best Available Techniques
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‘Best Available Techniques’ for a specific
installation will usually be the use of one
individual or a combination of the
techniques.
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BAT AEL does not define and suggest
emission limit values (ELVs) because they
are related to installations.
Best Available Techniques
‘Best Available Techniques’ can be divided
in two groups:
 GENERIC
 SECTOR
Best Available Techniques.
SPECIFIC Best Available
Techniques.
Best Available Techniques
GENERIC Best Available Techniques refer to the
following areas:
Environmental management.
 Energy.
 Dust emissions.
 Gaseous compounds.
 Process waste water (emissions and consumption).
 Sludge.
 Solid process losses/solid waste.
 Noise.
BAT are defined for each of these areas.
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Best Available Techniques
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BAT is to reduce energy:
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BAT is to reduce diffuse dust emissions:
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Improved design of kilns and dryers.
Recovery of excess heat from kilns.
Applying a fuel switch in the kiln firing process.
Modification of ceramic bodies.
Reduce primary energy consumption by applying cogeneration/combined heat and
power plants.
Measures for dusty operations.
Bulk storage area measures.
BAT is to reduce the emissions of gaseous compounds:
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Reducing the input of pollutant precursors.
Heating curve optimisation.
Cascade-type packed bed adsorbers.
Dry flue-gas cleaning with a filter (bag filter or electrostatic precipitator).
Best Available Techniques
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BAT is to reduce solid process losses/solid waste:
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Feedback of unmixed raw materials.
Feedback of broken ware into the manufacturing process.
Use of solid process losses in other industries.
Electronic controlling of firing.
Applying optimised setting.
BAT is to reduce noise:
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Enclosure of units.
Vibration insulation of units.
Using silencers and slow rotating fans.
Situating windows, gates and noisy units away from neighbours.
Sound insulation of windows and walls.
Closing windows and gates.
Carrying out noisy (outdoor) activities only during the day.
Good maintenance of the plant.
Best Available Techniques
SECTOR SPECIFIC Best Available Techniques refer
to the following areas:
Bricks and roof tiles.
 Vitrified clay pipes.
 Refractory products.
 Expanded clay aggregates.
 Wall and floor tiles.
 Table- and ornamental ware (household ceramics).
 Technical ceramics.
 Sanitaryware.
 Inorganic bonded abrasives.
Of the same way, BAT are defined for each of these areas.
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Best Available Techniques
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BAT is to reduce the emissions of gaseous compounds by addition of calcium
rich additives, if the quality of the end-product is not affected.
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BAT is to reduce the emissions of volatile organic compounds by applying
activated carbon filters or thermal afterburning either in a one or a three chamber
thermoreactor.
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BAT is to reduce channelled dust emissions by applying bag filters, sintered
lamellar filters, electrostatic precipitators or wet dust separators.
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BAT is to reduce the amount of solid process losses/solid waste by applying one
individual or a combination of the following measures:
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Replacing plaster moulds by polymer moulds.
Replacing plaster moulds by metal moulds.
Us of vacuum plaster mixers.
Re-use of used plaster moulds in other industries.
Emerging techniques for ceramic
manufacturing
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Radiant tube burners
2 Microwave assisted firing and microwave
dryers
3 New type of drying system for refractory
products
4 Advanced process waste water
management with integrated glaze recovery
5 Lead-free glazing of high quality table
porcelain
1 Radiant tube burners
Reduction of water vapour levels → usually
results in lower emission rates for HF as well as
of SOx.
• Technicaly difficult→that water is produced by
the fossi fuels used tohead the kiln.
• Solution → radiant-tube burners
Heat transfer is carried by thermal radiation.
Applied in roller hearth kilns and shuttle kilns, not
yet proven for tunnel kilns.
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2 Microwave assisted firing and
microwave dryers
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Heat transfer from the outside to the middle of
the setting and into the centre of individual bricks
is difficult. → Temperature gradients can lead to
thermal stresses and damaged products
Solution; microwave energy heats the product
directly – including the centre of the units.
microwave energy has been used in
combination with conventional heating such as
gas or electrical energy.
2 Microwave assisted firing and
microwave dryers
Benefits
 minimisation of thermal stresses throughout
the firing cycle
 reduction of solid process losses/solid waste
 reduced emissions based upon less energy
consumption and higher production output
→can also be used for drying ceramic ware
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3 New type of drying system for
refractory products
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The drying of large size refractory building
components is very time consuming and energy
intensive.
By placing heat resistant stainless steel foils or
carbon fibres as the heating element →As drying
takes place from the inside out, the water
moves in the same direction as the temperature
front. This reduces drying times considerably
and reduces the energy requirement even 90%.
4 Advanced process waste water
management with integrated
glaze recovery
An innovative model waste water treatment system
→reductions in pollutants and savings in the
manufacture.
The new process waste water system has five modules:
1.
Microfiltration.
2.
treatment of a tributary process waste water stream.
3.
inclusion of existing sedimentation tanks.
4.
construction of a new central process waste water
treatment plant.
5.
separation of rainwater.
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4 Advanced process waste water
management with
integrated glaze recovery
Cost advantages
• reduction of personnel costs to 20 % of the
original number of staff required through
automation
• reduction of energy costs
• reduction in chemical additives
• recovery of re-usable glaze
• reduction of landfill costs.
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4 Advanced process waste water
management with
integrated glaze recovery
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Potential disadvantages:
energy costs for the filtration technology
incorrect design of the microfiltration plant
long phase of research into the use of recovered
glaze
high technical competence is necessary
regarding the overall system
redundancy measures have to be taken into
account in the planning phase.
5 Lead-free glazing of high
quality table porcelain
Lead glazes have been used in the past mainly
for high quality table porcelain.
→lead-free glaze formulations based on alkali
boron silicates have been developed by a
tableware producer.→annual savings in lead
oxide of 60 tonnes. A higher energy requirement
is needed for the treatment and recovery of
process waste water
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