4C.1 Emission
Rate Calculations
Submerged
Combustion Vaporizers (SCVs)
Total emissions: NOx = 51 tonnes/yr and CO = 257 tonnes/yr (provided
by Vendor’s equipment information, emissions are based upon 30 t/hr and flue
gas produced per 100 t/hr LNG vaporization)
No. of SCVs
= 5
Emission rate
of each SCV:
NOx =
(51 tonnes / 365 days / 24 hours / 3600 s) x 1x106 / 5 = 0.32 g/s
CO =
= (257 tonnes / 365 days / 24 hours / 3600 s) x 1x106 / 5 = 1.63 g/s
Total flowrate = 130,000 Nm3hr-1 (at 0 °C
& 101.3 kPa)
At exhaust
temperature of 30 °C,
the total flowrate = 144,285.71 m3hr-1
Stack velocity
of each SCV = 144,285.71 / 5 / 3600 / (p x
0.62) = 7.09 ms-1
LNG
Carrier – Auxiliary Engines
·
Total generator capacity = 9,350 kW
(under 75% load factor)
·
Generator load factor = 75%
·
Burning Marine Diesel Oil (MDO) or
Heavy Fuel Oil (HFO)
According to
IMO MARPOL Annex VI, NOx is limited by the
formula:
45.0 x rpm-0.2 g/kWh
The auxiliary
generator will be operating at 720 rpm and therefore, NOx
emission will be 12.07 g/kWh. At
75% load, the NOx can vary from 7% to 15%
and therefore, upper limit of NOx emission
will be 12.07 x 1.15 = 13.88 g/kWh.
NOx g emission
factor = 13.88 g/kWh
SO2
emission factor = 6 g/kWh (based on 1.5% sulphur content)
CO emission
factor = 0.6 /kWh
Emission rate
from one chimney:
NOx =
(13.88 g/kWh x 9,350 kW) / 3600 = 36 g/s
SO2 =
(6 g/kWh x 9,350 kW) / 3600 = 15.6 g/s
CO = (0.6
g/kWh x 9,350 kW) / 3600 = 1.56 g/s
As 3
individual stacks are enclosed in a single chimney, therefore, effective
diameter = 0.78 m
Exhaust gas
velocity = 25 ms-1
Exhaust
temperature = 320 °C
Pipeline
Gas Heater
Total emissions
: 72 tonnes of NOx and 45 tonnes of
CO a year (based on 4.1 MMSCFD for the Design Case)
Total no. of
stack = 4
Emission rate of each stack:
NOx =
(72 tonnes / 365 days / 24 hours / 3600 s) x 1x106 /4 = 0.57 g/s
CO =
(45 tonnes / 365 days / 24 hours / 3600 s) x 1x106 / 4 = 0.36 g/s
Total flowrate = 73,900 Nm3hr-1 (at 0 °C
& 101.3 kPa)
At exhaust
temperature of 280 °C, the total flowrate = 149,695 m3hr-1
Stack velocity
= 149,695 / 3600 / 4 / (p x 0.542) = 11.56 ms-1
Summary
of Modelling Parameters
|
SCV |
LNG Carrier – Auxiliary Engine |
Pipeline Gas Heater |
No.
of Emission Sources |
5 |
1 |
4 |
Stack
Height (m) |
13 |
41 |
15 |
Stack
Diameter (m) |
1.2 |
0.78 |
1.07 |
Exit
Temperature (°C) |
30 |
320 |
280 |
Exit
Velocity (m/s) |
7.09 |
25 |
11.56 |
NOx Emission Rate (g/s) |
0.32 |
36 |
0.57 |
SO2
Emission Rate (g/s) |
- |
15.6 |
- |
CO
Emission Rate (g/s) |
1.63 |
1.56 |
0.36 |