nitrogenous fertilizer

8/4/2019 Nitrogenous Fertilizer

1/13

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]


2/13

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


3/13

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


4/13

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


5/13

CONTD..

(g) (g) (s/melt)

SIDE REACTION

RAW MATERIALS

Ammonia Carbon dioxide


6/13

Process Flow Sheet


7/13

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


8/13

Reference to Flowsheet [Dryden] Principal Reactions

Ammonium Carbamate formation;

(g) (s/melt)

Ammonium Carbamate decomposition+

(s/melt) (s) (l)

Side reaction (biuret formation)


9/13

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.


10/13


11/13

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


12/13

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


13/13

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?

nitrogenous fertilizer

Documents