410
2
Experimental
z. Spiric and M. Hraste
In order to investigate and provide precise and accurate data (original processing
results), and to establish crucial information and knowledge about the activated
carbon bed saturation profile, we studied a mercury removal system for natural
gas under actual processing conditions (Table Ib).
The mercury removal unit (MRU) consists of an adsorber (Fig. Ib) located in
the process plant, treating water-washed natural gas (Table la). Besides
hydrocarbons (more than 70% methane), natural gas contains CO2, H2S, and
near saturated levels of water vapour. The MRU contains 64 m 3 commercial
granular pelletised sulphur-impregnated activated carbon (Table IC) and is
designed to remove mercury to a level no greater than 5 ~lg/m3.
Table 1. Typical process features of the Mercury Removal Unit (MRU)
a) Inlet stream composition (vol%)
C,
C2
C,
i-C.
n-C.
i-Cs
n-C,
Cs+
CO2
N2
H2S
RSH
H 20
Hg
b) Process design conditions
Flow rate
Temperature
Pressure
Molecular weight
Density
Viscosity
Max. dP
c) Activated carbon
Total sulphur content
Apparent bulk density
Moisture
Ash (gravimetric)
Sodium (AAS)
Potassium (AAS)
Average pore diameter
69.32
3.33
0.79
0.21
0.23
0.12
0.08
0.18
23.74
2.0
150 ppm.
30 mg/m 3
0.11 mol%
1000 flg/m·'
5000000 Nm'/day (218564 kg/h)
55-60 DC
5200-6000 kPa (52-60 barg)
23.5 kg/kmol
58.5-62.8 kg/m'
0.011 cP
57 kPa (0.57 bar)
15%
560 kg/m"
11.8% mlm
4.4% mlm
0.185% mlm
0.055% mlm
15.9 x 10 10 m (\5.9 A)