nitrogenous fertilizer
TRANSCRIPT
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NITROGENOUS FERTILIZERS
AMMONIA [NH3]
UREA [(NH2)2.CO]
AMMONIUM NITRATE [NH4NO3]
AMMONIUM SULPHATE [(NH4)2SO4]
AMMONIUM CHLORIDE [NH4Cl]
MIXED NITROGEN CONTAINING PRODUCTS
MAP [ NH4.H2PO4]
DAP [(NH4)2HPO4]
POTASSIUM NITRATE [KNO3]
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UREA
Amongst richest sources of Nitrogen,
most popular
Fertilizer grade : as prills, coated with lime
stone/phosphate rock
[Elsewhere as Liquor : Urea, NH3 solutions]
Other uses
Animal Feed
Resins [ Urea Formaldehyde]
Melamine
Adhesives
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PRODUCTION [India] ; 106t
2005-06 06-07 07-08 08-09 09-10
20.09 20.27 19.84 19.92 21.12
IMPORTS
2.06 4.72 6.93 5.67 5.12
SUBSIDY [US$109]
2.64 3.54 5.12 6.78 4.00
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PROJECTED USAGE [106t]
2010-11 11-12 12-13 13-14
27.56 28.28 29.25 29.96
SHORTAGE
6.31 7.03 8.00 8.71
Plants needed 8 10 11 12
(2250tpd)
100% capacity
utilization
Where are the plants?
- Gestation period
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CONTD..
(g) (g) (s/melt)
SIDE REACTION
RAW MATERIALS
Ammonia Carbon dioxide
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Process Flow Sheet
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CRITICAL PARAMETERS
Temperature
Pressure
NH3/CO2 mol ratio
Operating pressure > dissociation pr. of carbamate
Dissociation pr with temperature
CHALLENGES
Corrosion MOC
Bouret formation
Management of excess reactant
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Reference to Flowsheet [Dryden] Principal Reactions
Ammonium Carbamate formation;
(g) (s/melt)
Ammonium Carbamate decomposition+
(s/melt) (s) (l)
Side reaction (biuret formation)
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Features
Separate compression of ammonia and Carbon dioxide [why?]
Carbamate formation non catalytic temperatures for reasonable rates 1800C
Dissociation pr. Of Carbamate 1800C is >100 atm.
Rate increases with increase in pressure.
Increase in temperature increases biuret formation
Use of excess ammonia provides a slight advantage [compression costs?]
Typical Reactor (Autoclave) conditions
- Temperatures 1700C - 1900C
- Pressures 100-200 atm.
- Feed NH3/CO2 mol ratio:2.0 plus- Av. residence time (continuous reactor !!)
1.5 2.0 h.
- 45-50% Conversion [single pass]
Reactor operation conditions:
- compromise/optimization between thermo, kinetics and corrosion.
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Carbamate Decompositiono In stages
- Stage 1 : Flash to27 atm; 1400C steam heating
prior to flashing/in flash chamber
Water cooling to condense flashed gases
Gases + condensate recycle
Melt to steam heater
- Stage 2 : Flash to 1 atm. Gases to recycle
melt to steam heater & vacuum evaporator
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Evaporation, Finishing- evaporator product 99% urea
melt- prilling:
cooling/drying in : counter
current spray tower- prills/granules:small 2-3 mmspherical particles
- coat: if necessary
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Other features
- high cooling water consumption
- modest steam consumption- rarely stand alone; adjucnt to
NH3
plants
Why is urea the most preferred
Nitrogenous Fertilizer vis--vis
Other Nitrogen rich Fertilizers?