Integrated environmental management
in Dung Quat refinery
Priority for environmental management
1. Reduce
2. Reuse
4. Final Treatment
Waste
Raw material
• Using efficient energy
• Improve technology
• Saving
• Cleaner production
1. Reduce
2. Reuse
3. Recycle
1. Reduce
2. Reuse
4. Final Treatment
3. Recycle
1. Reduce
2. Reuse
1. Reduce
2. Reuse
4. Final Treatment
1. Reduce
2. Reuse
3. Recycle
4. Final Treatment
1. Reduce
2. Reuse
Air pollution control

Devices
Reduced
emission
Stack
Cleaner
production
Control
Devices
Air pollution control
Cleaner production (treatment at the source)
• Remove H
2
S out of gas (Gas Plant, LTU)
(C
2
H
4
ỌH)
2
NH (DEA) +H
2
S  (C
2
H
4
OH)
2
NH
2
HS

• Treatment of gas streams (rich H
2
S) from unit ARU, CNU,
SWS
• Purpose: - Protect of Environment
– Recovery of Sulfur
• H
2
S gas is very toxic, odor (rotten egg) S (solid) is easy to
handle and control and it can be sold for fertilizer production
• Reaction for S recovery (Gauss)
H
2
S + 3/2 O
2
= SO
2
+H
2
O
SO
2
+2H
2
S = 3S+2H
2
O
3H
2
S + 3/2 O

• Treats large volumes of gas
• Produces only low pressure drops
• Economical to operate
• Offers dry collection of valuable products
• Generates dry waste for disposal or recycle
End of Pipe control
Feed Residue
Air
DeSOx
CO Boiler
WHB
Reactor/Regenerator
Steam
Economizer
MTC
Discharge
electrodes
Flue gas in
Clean
gas out
Hoppers
Rappers
ESP
Electrostatic Precipitator (ESP)
End of Pipe control
Air pollution control of RFCC unit
• Control SOx (DeSO
x
)
SOx formed when burning oil or gas containing S

the reaction as follow:
– SO
2
+ Ca(OH)
2
+ H
2
O => CaSO
3
.1/2H
2
O + 3/2H
2
O
– CaSO
3
.1/2H
2
O + 3/2H
2
O + 1/2O
2
=> CaSO
4
.2 H
2
O
– SO
2
+ CaCO

eliminator
spray water
Exhaust to
atmosphere
Inlet gas
stream
∆
p
∆
p
T
F
P
pH
T
T
Typical process flow diagram for alkaline (Ca(OH)
2
, NaOH… ) scrubbing
High concentration
of SO
2
End of Pipe control
• Formation of NOx from air Nitrogen
– NO increases with T°C, significant at >700°C
– NOx in flue gas: 500-1000 ppm (90% NO + 10% NO
2
)
• Concentration of NO
x

3
etc.) selectively react with NO
x
in presence of
catalyst => reduces NO
x
to N
2
and O
2
CO as reducing agent, Pt catalyst reaction as follow:
2CO + 2NO = CO
2
+N
2
4CO + 2NO
2
= 4CO
2
+ N
2
– Selective non-catalytic reduction (SNCR):
Injection of reactants (NH
3
or urea based compounds) with high T
o
(optimum: 930-1090
o
C ) => high activation, no need catalyst
Reactant: NH

– Properties:
• Seawater
• For cooling of fresh water
• Outlet is 8
o
C higher than inlet
• Biocide injected (HOCl
3
)
– Treatment:
Direct discharge to the sea, but
Monitoring
• Temperature
• Residue Chlorine
Verify the
compliance
with the TCVN
5945
Monitoring
• Temperature
• Residue Chlorine
• Raining/storm water
– Properties:
• The first 55 mm raining water containing oil and suspended
solid (SS) so it is considered as OWS
• If it is higher than 55mm it is characterized as SS only
– Treatment:
• The first 50mm raining water is treated as OWS (will be
discussed later)
• The next raining it is discharged directly to the sea

– Treatment
CPI
Mixed with high
concentration
of phenol stream for
further treatment
OWS
Management of wastewater
• Oily Surface Water (OWS)
CPI
Mixed with high
concentration
of phenol stream for
further treatment
CPI
Mixed with high
concentration
of phenol stream for
further treatment
•Stripped Sour Water (SSW)
– Properties:
Phenol: 258mg/L
– Treatment (Primary treatment)
Due to the high phenol content in this stream and the stringent standard
imposed on phenol residuals (0.05mg/L), it is treated by activated sludge
treatment after cooling and coagulation step. The pre-treated effluent is
directed to balancing tank.
Heat
exchanger
Return sludge