Transcript Diapositiva 1

Departamento de
INGENIERÍA QUÍMICA y
UNIVERSIDAD
DE
VALLADOLID
TECNOLOGÍA
del MEDIO AMBIENTE
NPK
Grupo 1
Alicia Aguado Pesquera
Jésica Calvo Bravo
Laura Fraile Escudero
Chemical Eng. &
Environm. Techs.
Department
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
1. GENERAL
INFORMATION
NPK
Chemical Eng. &
Environm. Techs.
Department
1. GENERAL INFORMATION NPK
NPK
1. General info
2. Processes
Product types are PK, NP, NK and NPK.
3. Emissions
These products might contain:
4. Techniques
• Nitrogen, expressed as % of N, in ureic, ammoniacal and/or nitrate
forms.
5. BAT
• Phosphorus, usually expressed as % of P2O5, in forms soluble in water
and/or neutral ammonia citrate and/or mineral acids.
• Potassium, usually expressed as % of K2O, in forms soluble in water.
• Secondary nutrients, as calcium (CaO), magnesium (MgO), sodium
(Na2O) and/or sulphur (SO3).
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NPK
• Microelements (zinc, copper, boron, etc.).
• Other elements.
Chemical Eng. &
Environm. Techs.
Department
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
2. APPLIED
PROCESSES
AND
TECHNIQUES
Chemical Eng. &
Environm. Techs.
Department
2. APPLIED PROCESSES AND TECHNIQUES
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
 The demand for NPK fertilisers in various compositions results
basically in two plant types:
• Production by the mixed acid route.
• Production by the nitrophosphate route.
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NPK
Chemical Eng. &
Environm. Techs.
Department
2. APPLIED PROCESSES AND TECHNIQUES
1. General info
2. Processes
3. Emissions
Compound fertilisers can be produced in four, basically different, ways:
4. Techniques
• Production by the mixed acid route, without phosphate rock digestion.
5. BAT
• Production by the mixed acid route, with phosphate rock digestion.
• Production by the nitrophosphate route (ODDA process).
• Mechanical blending or compactation of single or multi-nutrient
components.
Grupo 1
NPK
Chemical Eng. &
Environm. Techs.
Department
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
2. APPLIED PROCESSES AND TECHNIQUES
Chemical Eng. &
Environm. Techs.
Department
2. APPLIED PROCESSES AND TECHNIQUES
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
• Direct neutralisation (pipe reactor): Various amounts of H3PO4, H2SO4
and HNO3 are neutralised in pipe reactors with gaseous or liquid NH3.
• Pre-neutralisation
The conventional slurry process is carried out in a series of tanks/reactors,
using a preneutraliser.
Various amounts of H3PO4, H2SO4 and HNO3 are neutralised with NH3 and
the resulting slurry can be partly evaporated to achieve the water content
necessary for the subsequent particle formation.
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NPK
• Phosphate rock digestion is carried out with nitric acid (nitrophosphate
route) or with a combination of nitric, sulphuric and/or phosphoric acids
(mixed acid route).
Chemical Eng. &
Environm. Techs.
Department
2. APPLIED PROCESSES AND TECHNIQUES
1. General info
2. Processes
3. Emissions
Particle formation and conditioning
The options for particle formation include:
4. Techniques
5. BAT
Grupo 1
NPK
• spherodiser.
• granulation drum.
• prill tower.
• pugmill (also called blunger) granulation.
• pan granulation.
• compaction.
Chemical Eng. &
Environm. Techs.
Department
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
2. APPLIED PROCESSES AND TECHNIQUES
Conversion of Ca(NO3)2·4 H2O
The production of NPK fertilisers by digestion of phosphate
rock with HNO3 in the ODDA process produces calcium
nitrate tetra hydrate (CNTH, Ca(NO3)2. 4 H2O) as a byproduct.
NH3 and CO2 are dissolved in an NH4NO3 solution, which is
carbonising column: 2 NH3 + CO2 + H2O  (NH4)2CO3
CNTH is dissolved in a NH4NO3 solution and both solutions
react according to:
Ca(NO3)2 + (NH4)2CO3  2 NH4NO3 + CaCO3
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
3. EMISSIONS.
Chemical Eng. &
Environm. Techs.
Department
3. EMISSIONS
1. General info
Emission sources into air and exhaust gas treatment
2. Processes
3. Emissions
Exhaust gases arise from various sources. The main pollutants are:
4. Techniques
5. BAT
• NOx (mainly NO and NO2) with some nitric acid. The main source
of NOx is the dissolution of phosphate rock in nitric acid.
• NH3 originating from the neutralisation process.
• Fluorine compounds originating from the phosphate rock.
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NPK
Chemical Eng. &
Environm. Techs.
Department
3. EMISSIONS
1. General info
Emission sources into air and exhaust gas treatment
2. Processes
3. Emissions
4. Techniques
Exhaust gas treatment might include:
• Wet scrubbing of exhaust gases from phosphate rock digestion.
5. BAT
• Condensation of neutralisation/evaporation vapours.
• Combined scrubbing of exhaust gases from neutralisation/
evaporation and particle formation and conditioning.
• Cyclones and fabric filters for dry dedusting.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
4. TECHNIQUES
TO CONSIDER IN
THE
DETERMINATION
OF BAT.
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
4.1. Minimisation of NOx formation.
3. Emissions
4. Techniques
5. BAT
NOx loads in exhaust gases from the digestion phosphate
rock can be minimised by a selection of proper operating
conditions:
- Control temperature.
- Correct ratio of rock phosphate/acid.
- Etc.
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NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
4.2. Particle formation I: Spherodiser.
3. Emissions
4. Techniques
5. BAT
- Granulation of produced slurries is carried out in
spherodiser  granulation and drying in a single process
step.
- Spherodiser consists of an inclined rotary drum, divided
into a granulation and a drying zone.
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NPk
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
3. Emissions
4.3. Particle formation II: Drum
granulation.
4. Techniques
5. BAT
Feed: NP liquor obtained from neutralisation with a water
content is mixed with the required salts and recycled
products and is pumped and sprayed into a rotating drum
granulator.
The water evaporated in the drum is carried away by a cocurrent flow of air.
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NPK
The granules formed are dried in a rotating drying drum with
hot air
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
4.4. Particle formation III: Prill tower.
Evaporated NP liquor from neutralisation is mixed with the
required salts and recycled product.
The mixer overflows into a rotating prill bucket from which
the slurry is sprayed into the prill tower.
Fans at the bottom of the tower and the solid prills fall onto a
rotating tower bottom and are scraped off and forwarded to
the dry handling system.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
4.5. Plate bank product cooler.
3. Emissions
4. Techniques
5. BAT
The unit consists of a vertical bank of hollow, stainless steel
plates.
The bulk solids pass through a feed hopper and pass slowly
between the plates while cooling water is passed
countercurrently.
The material is discharged on the bottom.
Achieved environmental benefits:
- reduced emissions to air.
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NPK
- energy savings.
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
4.6. Recycling warm air.
1. Take the warm air (60-65 ºC) and use fabric filter or high
efficiency cyclones to recover the dust.
2. The warm air is recycled as dilution air to the dryer
combustion system, replacing ambient air.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
4.7. Optimising the recycle ratio to
granulation.
Another methods of maximising plant efficiency:
- Select proper combination of screens and mills.
- Online product size distribution management.
- Surge hoppers.
- Etc.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
4.8. Conversion of Ca(NO3)2·4H2O into
CN.
1. Neutralisation and evaporation: The CNTH crystals
from the nitrophosphoric acid unit are heated to form a melt
which is pumped to a two-stage atmospheric tank reactor
system for neutralisation with gaseous ammonia. This
reaction is exothermic. The 60% CNTH melt, containing
small amounts of ammonium nitrate, is evaporated in one or
two stages to a final concentration of 85% and this
concentrated solution is then transferred to the prilling or
pan granulation process.
2. Pan granulation: The concentrated melt from the
evaporator system is sprayed into the pan granulator
together with the recycled fines.
3. Prilling.
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
4.9. Multistage scrubbing of exhaust
gas containing NOx.
For multistage scrubbing in NPK production, exhaust gas
are collected from the following sources:
- phosphate rock digestion.
- separation/washing of sand.
- filtration/washing of Ca(NO3)2·4H2O (CNTH).
Applicable for AN-based NPK production.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
4.10. Combined treatment of exhaust gas from
neutralisation/
evaporation and granulation.
In this technique a new combined waste gas scrubber was
installed for treating exhaust gas or vapours from neutralisation or
evaporation and exhaust gas from two spherodisers.
Instead of condensing the vapours from neutralisation or
evaporation, they are combined with the hot exhaust gas from the
spherodiser and the added heat leads to additional evaporation of
H2O in the scrubber. The additional H2O removal enables the
recycling of all scrubber liquids (and the contained nutrients) to the
production process.
The achieved environmental benefits are that with the combined
treatment, a considerable amount of waste water from the
scrubbing of exhaust gas from neutralisation/evaporation and the
spherodisers is avoided and the AN solution can be recycled to the
process.
Only applicable for AN-based NPK production.
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
4.11. Recycling of scrubbing and
washing liquors.
The following measures result in a considerable reduction of
waste water volumes from NPK production:
- recycling of NOx loaded scrubber liquors from treatment of
exhaust gas from phosphate rock digestion.
- recycling of washing liquor from sand washing.
- avoid co-condensation of vapours from the evaporation.
- recycling of scrubbing liquors from scrubbing of exhaust
gas from neutralisation.
- combined scrubbing of exhaust gas from neutralisation or
evaporation and granulation units.
- using effluents as the scrubber medium.
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
4.TECHNIQUES TO CONSIDER IN THE DETERMINATION OF BAT
1. General info
2. Processes
3. Emissions
4.12. Waste water treatment.
4. Techniques
Waste water that cannot be avoided is discharged after
adequate treatment, e.g. biological waste water treatment
with nitrification/desnitrification and precipitation of
phosphorous compounds.
5. BAT
The achieved environmental benefits are the lower emission
levels to water.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
Grupo 1
NPK
5. BAT FOR
NPK
FERTILISERS.
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
5. BAT FOR NPK FERTILISERS
1. General info
2. Processes
BAT = BEST AVAILABLE TECHNIQUES
3. Emissions
BAT is to:
4. Techniques
- reduce dust emissions from rock grinding.
5. BAT
- prevent dispersion of phosphate rock dust by using
covered conveyor belts, indoor storage, and frequently
cleaning/sweeping the plant grounds and the quay.
- improve environmental performance of the finishing section
by one or a combination of some of the previous techniques.
- minimise the NOx load in exhaust gas from phosphate rock
digestion.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
del MEDIO AMBIENTE
5. BAT FOR NPK FERTILISERS
1. General info
2. Processes
3. Emissions
4. Techniques
5. BAT
- reduce emissions to air from phosphate rock digestion,
sand washing and CNTH filtration.
- reduce emission levels to air from
granulation, drying, coating and cooling.
neutralisation,
- minimise waste water volumes by recycling washing and
rinsing waters and scrubbing liquors into the process.
- treat the remaining waste water volumes.
Grupo 1
NPK
Departamento de
INGENIERÍA QUÍMICA y
TECNOLOGÍA
UNIVERSIDAD
DE
VALLADOLID
del MEDIO AMBIENTE
THANK YOU FOR YOUR
ATTENTION!!!
Grupo 1
Alicia Aguado Pesquera
Jésica Calvo Bravo
Laura Fraile Escudero