THE ECHO - Ferrostaal

28
ProjECtS
Natural
gas
AUM ammonia plant
1,850 t/d NH3 and 2,270 t/d CO2
839 t/d NH3
903 t/d NH3 and
1306 t/d CO2
426 t/d NH3
Urea solution
plant
2,076 t/d urea
as 70% solution
106 t/d NH3 and 8 t/d CO2
The structure of the new plant complex
The structure of the plant complex follows the intensity of
the added value. Its construction is carried out according to
state-of-the-art environmental and safety guidelines. From
the raw material natural gas, ammonia (NH3) is first recovered.
This, together with the carbon dioxide (CO2) also produced,
is then converted to urea solution ((NH2)2CO). Urea
is the source material for both fertiliser and melamine. In
the UAN plant, nitric acid (HNO3) is first produced from ammonia
and atmospheric oxygen. In a second process step,
this is neutralised with ammonia, producing ammonium ni-
Nitric acid plant
1,500 t/d (100%)
2,500 t/d (60%)
413 t/d NH3
Off solution,
equivalent to 280 t/d NH3,
230 t/d CO2
and rest water
576 t/d urea
as 70% solution
1,500 t/d
nitric acid
as 60% solution
Melamine plant 1
90 t/d Melamine
UAN plant
Ammonium nitrate
solution plant
1905 t/d (100%)
1,500 t/d urea as 70% solution
Melamine plant 2
90 t/d Melamine
trate (NH4NO3). This is then mixed with the urea solution
to make UAN, one of the main products of the plant complex.
UAN is characterised by a high content of nitrogen (typically
32 per cent by weight).
The second plant section is used for the manufacture of
melamine. From a chemical point of view, melamine has a
relatively simple structure. Here, “only” pure urea, recovered
from the thickened urea solution from the urea plant, reacts
under pressure and temperature to form melamine. Ammo-
1,905 t/d
AN as 91%
solution
THE ECHO August 2007
UAN mixing tank
4,274 t/d (UAN 32)
UAN-32 solution
Melamine powder
Cold ammonia
Normal 4,274 t/d
Design 4,300 t/d
Normal 180 t/d
Design 180 t/d
Normal 0 t/d
Design 1,850 t/d
nia and carbon dioxide are added to the process in small
quantities for regulation of the chemical balance and for purification
of the reaction product. A feature of Eurotecnica’s
melamine process is that all the ammonia and carbon dioxide
produced in the reaction and added to the process is returned
to the urea process as input material. The technical
process behind this, however, is very complex.
29
Chemical manufacturing processes
AMMONIA MANUFACTURE
KAAP Process (KBR, USA)
(Pressure = 90 barg and temperature = 400 °C)
3 H 2 + N 2 2 NH 3 + heat of reaction
UREA MANUFACTURE
ACES21 Process (Toyo Engineering Corporation, Japan)
(Pressure = 150 barg and temperature = 180 °C)
2NH 3 + CO 2 (NH 2 ) 2 CO + H 2 O - heat of reaction
UAN MANUFACTURE
A) NITRIC ACID MANUFACTURE
Dual Pressure Process (Uhde GmbH, Germany)
(Pressure = 4–6/10–12 barg and temperature = 890 °C)
(I) 4 NH 3 + 5 O 2 4 NO + 6 H 2 O
(II) 2 NO + O 2 2 NO 2
(III) 3 NO 2 + H 2 O 2 HNO 3 + NO
b) AMMONIUM NITRATE MANUFACTURE
Vacuum Neutralisation (Uhde GmbH, Germany)
(Pressure = 0.35 bar abs. and maximum temperature = 145 °C)
NH 3 (gas) + HNO 3 (aqueous)
NH 4 NO 3 (aqueous) + heat of reaction
C) AMMONIUM NITRATE-UREA SOLUTION (UAN)
Mixing Unit (Uhde GmbH, Germany)
Ammonium nitrate solution + urea solution UAN
MELAMINE MANUFACTURE
Non-Catalytic Process (Eurotecnica, Italy)
(Pressure = 80 barg and temperature = 380 °C)
6 (NH 2 ) 2 CO C 3 H 6 N 6 (Melamine) + 3 CO 2 + 6 NH 3 - heat
of reaction (return of NH 3 and CO 2 to the urea plant)
H
N +
H H
H
H H
O
C
N
H
H2 N NH 2
O
N +
- O OH
+ O -
N
N
O O
2 HN-C C-NH 2
N N
C
NH 2